{"page_0": [], "page_1": [], "page_2": [["block_0", ["!\n"]], ["block_1", [" \n \n \n \n \n Chemistry 2e \n"]], ["block_2", [" \n \n \n \n \n \n \n \n \n"]], ["block_3", ["SENIOR CONTRIBUTING AUTHORS \n PAUL FLOWERS, UNIVERSITY OF NORTH CAROLINA AT PEMBROKE \n KLAUS THEOPOLD, UNIVERSITY OF DELAWARE \n RICHARD LANGLEY, STEPHEN F. AUSTIN STATE UNIVERSITY \n WILLIAM R. ROBINSON, PHD \n \n \n \n \n \n \n \n \n"]], ["block_4", [{"image_0": "2_0.png", "coords": [72, 666, 251, 707]}]], ["block_5", ["!\n"]]], "page_3": [["block_0", ["!\n"]], ["block_1", [" OpenStax \nRice University \n6100 Main Street MS-375 \nHouston, Texas 77005 \n \nTo learn more about OpenStax, visit https://openstax.org. \nIndividual print copies and bulk orders can be purchased through our website. \n \n\u00a92019 Rice University. Textbook content produced by OpenStax is licensed under a Creative Commons \nAttribution 4.0 International License (CC BY 4.0). Under this license, any user of this textbook or the textbook \ncontents herein must provide proper attribution as follows: \n \n"]], ["block_2", [" \nFor questions regarding this licensing, please contact support@openstax.org. \n \n Trademarks \nThe OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, OpenStax CNX logo, \nOpenStax Tutor name, Openstax Tutor logo, Connexions name, Connexions logo, Rice University name, and \nRice University logo are not subject to the license and may not be reproduced without the prior and express \nwritten consent of Rice University. \n \n \n \n"]], ["block_3", [" HARDCOVER BOOK ISBN-13 \n 978-1-947172-62-3 \n"]], ["block_4", [" B&W PAPERBACK BOOK ISBN-13 \n 978-1-59399-578-2 \n"]], ["block_5", [" DIGITAL VERSION ISBN-13 \n 978-1-947172-61-6 \n"]], ["block_6", ["2 3 4 5 6 7 8 9 10 RS 22 19 \n \n"]], ["block_7", [" \n \n"]], ["block_8", [" \n \n"]], ["block_9", ["!\n"]], ["block_10", ["- \nIf you redistribute this textbook in a digital format (including but not limited to PDF and HTML), then you \nmust retain on every page the following attribution: \n\u201cAccess for free at openstax.org.\u201d \n"]], ["block_11", ["- \nIf you redistribute this textbook in a print format, then you must include on every physical page the \nfollowing attribution: \n\u201cAccess for free at openstax.org.\u201d \n"]], ["block_12", ["- \nIf you redistribute part of this textbook, then you must retain in every digital format page view (including \nbut not limited to PDF and HTML) and on every physical printed page the following attribution: \n\u201cAccess for free at openstax.org.\u201d \n"]], ["block_13", ["- \nIf you use this textbook as a bibliographic reference, please include \nhttps://openstax.org/details/books/chemistry-2e in your citation. \n"]]], "page_4": [["block_0", ["!\n"]], ["block_1", [" O PEN S TAX \n \nOpenStax provides free, peer-reviewed, openly licensed textbooks for introductory college and Advanced \nPlacement\u00ae courses and low-cost, personalized courseware that helps students learn. A nonprofit ed tech \ninitiative based at Rice University, we\u2019re committed to helping students access the tools they need to complete \ntheir courses and meet their educational goals. \n \n R ICE U NIVERSITY \n \nOpenStax, OpenStax CNX, and OpenStax Tutor are initiatives of Rice University. As a leading research \nuniversity with a distinctive commitment to undergraduate education, Rice University aspires to path-breaking \nresearch, unsurpassed teaching, and contributions to the betterment of our world. It seeks to fulfill this \nmission by cultivating a diverse community of learning and discovery that produces leaders across the \nspectrum of human endeavor. \n \n"]], ["block_2", [{"image_0": "4_0.png", "coords": [72, 253, 143, 282]}]], ["block_3", [" \n \n P HILANTHROPIC S UPPORT \n \nOpenStax is grateful for the generous philanthropic partners who advance our mission to improve educational \n"]], ["block_4", ["access and learning for everyone. 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Go \n"]], ["block_34", ["Stand Together \n"]], ["block_35", ["Robin and Sandy Stuart Foundation \n"]], ["block_36", ["The Stuart Family Foundation \n"]], ["block_37", ["Tammy and Guillermo Trevi\u00f1o \n"]], ["block_38", ["Valhalla Charitable Foundation \n"]], ["block_39", ["White Star Education Foundation \n"]], ["block_40", ["Schmidt Futures \n"]], ["block_41", ["William Marsh Rice University \n"]]], "page_5": [["block_0", [{"image_0": "5_0.png", "coords": [-316, 173, 620, 799]}]], ["block_1", [{"image_1": "5_1.png", "coords": [52, 336, 631, 714]}]], ["block_2", [" Access. The future of education. \n openstax.org \n"]], ["block_3", [{"image_2": "5_2.png", "coords": [71, 609, 541, 619]}]], ["block_4", [{"image_3": "5_3.png", "coords": [71, 618, 541, 626]}]], ["block_5", [" Study where you want, what \n you want, when you want. \n"]], ["block_6", [{"image_4": "5_4.png", "coords": [123, 368, 488, 659]}]], ["block_7", ["When you access College Success in our web view, you can use our new online \n"]], ["block_8", [" highlighting and note-taking features to create your own study guides.\n"]], ["block_9", ["Our books are free and flexible, forever. \nGet started at openstax.org/details/books/chemistry-2e \n"]], ["block_10", [{"image_5": "5_5.png", "coords": [267, 609, 345, 616]}]], ["block_11", [{"image_6": "5_6.png", "coords": [481, 702, 550, 732]}]]], "page_6": [["block_0", ["Contents\n"]], ["block_1", ["Preface\n1\n"]], ["block_2", ["CHAPTER 1\n Essential Ideas \n9\n"]], ["block_3", ["Introduction\n9\n"]], ["block_4", ["1.1 Chemistry in Context\n9\n"]], ["block_5", ["1.2 Phases and Classification of Matter\n14\n"]], ["block_6", ["1.3 Physical and Chemical Properties\n23\n"]], ["block_7", ["1.4 Measurements\n27\n"]], ["block_8", ["1.5 Measurement Uncertainty, Accuracy, and Precision\n33\n"]], ["block_9", ["1.6 Mathematical Treatment of Measurement Results\n41\n"]], ["block_10", ["Key Terms\n48\n"]], ["block_11", ["Key Equations\n49\n"]], ["block_12", ["Summary\n49\n"]], ["block_13", ["Exercises\n50\n"]], ["block_14", ["CHAPTER 2\n Atoms, Molecules, and Ions \n61\n"]], ["block_15", ["Introduction\n61\n"]], ["block_16", ["2.1 Early Ideas in Atomic Theory\n62\n"]], ["block_17", ["2.2 Evolution of Atomic Theory\n66\n"]], ["block_18", ["2.3 Atomic Structure and Symbolism\n71\n"]], ["block_19", ["2.4 Chemical Formulas\n79\n"]], ["block_20", ["2.5 The Periodic Table\n84\n"]], ["block_21", ["2.6 Ionic and Molecular Compounds\n89\n"]], ["block_22", ["2.7 Chemical Nomenclature\n96\n"]], ["block_23", ["Key Terms\n104\n"]], ["block_24", ["Key Equations\n105\n"]], ["block_25", ["Summary\n105\n"]], ["block_26", ["Exercises\n107\n"]], ["block_27", ["CHAPTER 3\n Composition of Substances and Solutions \n117\n"]], ["block_28", ["Introduction\n117\n"]], ["block_29", ["3.1 Formula Mass and the Mole Concept\n118\n"]], ["block_30", ["3.2 Determining Empirical and Molecular Formulas\n129\n"]], ["block_31", ["3.3 Molarity\n136\n"]], ["block_32", ["3.4 Other Units for Solution Concentrations\n144\n"]], ["block_33", ["Key Terms\n150\n"]], ["block_34", ["Key Equations\n150\n"]], ["block_35", ["Summary\n150\n"]], ["block_36", ["Exercises\n151\n"]]], "page_7": [["block_0", ["CHAPTER 4\n Stoichiometry of Chemical Reactions \n159\n"]], ["block_1", ["Introduction\n159\n"]], ["block_2", ["4.1 Writing and Balancing Chemical Equations\n160\n"]], ["block_3", ["4.2 Classifying Chemical Reactions\n166\n"]], ["block_4", ["4.3 Reaction Stoichiometry\n180\n"]], ["block_5", ["4.4 Reaction Yields\n185\n"]], ["block_6", ["4.5 Quantitative Chemical Analysis\n190\n"]], ["block_7", ["Key Terms\n198\n"]], ["block_8", ["Key Equations\n199\n"]], ["block_9", ["Summary\n199\n"]], ["block_10", ["Exercises\n200\n"]], ["block_11", ["CHAPTER 5\n Thermochemistry \n211\n"]], ["block_12", ["Introduction\n211\n"]], ["block_13", ["5.1 Energy Basics\n212\n"]], ["block_14", ["5.2 Calorimetry\n221\n"]], ["block_15", ["5.3 Enthalpy\n233\n"]], ["block_16", ["Key Terms\n247\n"]], ["block_17", ["Key Equations\n248\n"]], ["block_18", ["Summary\n248\n"]], ["block_19", ["Exercises\n248\n"]], ["block_20", ["CHAPTER 6\n Electronic Structure and Periodic Properties of Elements \n257\n"]], ["block_21", ["Introduction\n257\n"]], ["block_22", ["6.1 Electromagnetic Energy\n258\n"]], ["block_23", ["6.2 The Bohr Model\n270\n"]], ["block_24", ["6.3 Development of Quantum Theory\n274\n"]], ["block_25", ["6.4 Electronic Structure of Atoms (Electron Configurations)\n287\n"]], ["block_26", ["6.5 Periodic Variations in Element Properties\n295\n"]], ["block_27", ["Key Terms\n304\n"]], ["block_28", ["Key Equations\n305\n"]], ["block_29", ["Summary\n305\n"]], ["block_30", ["Exercises\n307\n"]], ["block_31", ["CHAPTER 7\n Chemical Bonding and Molecular Geometry \n313\n"]], ["block_32", ["Introduction\n313\n"]], ["block_33", ["7.1 Ionic Bonding\n313\n"]], ["block_34", ["7.2 Covalent Bonding\n317\n"]], ["block_35", ["7.3 Lewis Symbols and Structures\n322\n"]], ["block_36", ["7.4 Formal Charges and Resonance\n332\n"]], ["block_37", ["7.5 Strengths of Ionic and Covalent Bonds\n336\n"]], ["block_38", ["7.6 Molecular Structure and Polarity\n343\n"]], ["block_39", ["Key Terms\n358\n"]], ["block_40", ["Key Equations\n359\n"]], ["block_41", ["Summary\n359\n"]], ["block_42", [" Access for free at openstax.org \n"]]], "page_8": [["block_0", ["Exercises\n360\n"]], ["block_1", ["CHAPTER 8\n Advanced Theories of Covalent Bonding \n375\n"]], ["block_2", ["Introduction\n375\n"]], ["block_3", ["8.1 Valence Bond Theory\n376\n"]], ["block_4", ["8.2 Hybrid Atomic Orbitals\n379\n"]], ["block_5", ["8.3 Multiple Bonds\n390\n"]], ["block_6", ["8.4 Molecular Orbital Theory\n393\n"]], ["block_7", ["Key Terms\n408\n"]], ["block_8", ["Key Equations\n408\n"]], ["block_9", ["Summary\n409\n"]], ["block_10", ["Exercises\n409\n"]], ["block_11", ["CHAPTER 9\n Gases \n415\n"]], ["block_12", ["Introduction\n415\n"]], ["block_13", ["9.1 Gas Pressure\n416\n"]], ["block_14", ["9.2 Relating Pressure, Volume, Amount, and Temperature: The Ideal Gas Law\n425\n"]], ["block_15", ["9.3 Stoichiometry of Gaseous Substances, Mixtures, and Reactions\n437\n"]], ["block_16", ["9.4 Effusion and Diffusion of Gases\n449\n"]], ["block_17", ["9.5 The Kinetic-Molecular Theory\n454\n"]], ["block_18", ["9.6 Non-Ideal Gas Behavior\n458\n"]], ["block_19", ["Key Terms\n462\n"]], ["block_20", ["Key Equations\n462\n"]], ["block_21", ["Summary\n463\n"]], ["block_22", ["Exercises\n464\n"]], ["block_23", ["CHAPTER 10\n Liquids and Solids \n475\n"]], ["block_24", ["Introduction\n475\n"]], ["block_25", ["10.1 Intermolecular Forces\n476\n"]], ["block_26", ["10.2 Properties of Liquids\n487\n"]], ["block_27", ["10.3 Phase Transitions\n493\n"]], ["block_28", ["10.4 Phase Diagrams\n503\n"]], ["block_29", ["10.5 The Solid State of Matter\n510\n"]], ["block_30", ["10.6 Lattice Structures in Crystalline Solids\n516\n"]], ["block_31", ["Key Terms\n534\n"]], ["block_32", ["Key Equations\n535\n"]], ["block_33", ["Summary\n535\n"]], ["block_34", ["Exercises\n536\n"]], ["block_35", ["CHAPTER 11\n Solutions and Colloids \n547\n"]], ["block_36", ["Introduction\n547\n"]], ["block_37", ["11.1 The Dissolution Process\n548\n"]], ["block_38", ["11.2 Electrolytes\n552\n"]], ["block_39", ["11.3 Solubility\n555\n"]], ["block_40", ["11.4 Colligative Properties\n564\n"]]], "page_9": [["block_0", ["11.5 Colloids\n583\n"]], ["block_1", ["Key Terms\n592\n"]], ["block_2", ["Key Equations\n593\n"]], ["block_3", ["Summary\n593\n"]], ["block_4", ["Exercises\n594\n"]], ["block_5", ["CHAPTER 12\n Kinetics \n599\n"]], ["block_6", ["Introduction\n599\n"]], ["block_7", ["12.1 Chemical Reaction Rates\n600\n"]], ["block_8", ["12.2 Factors Affecting Reaction Rates\n605\n"]], ["block_9", ["12.3 Rate Laws\n607\n"]], ["block_10", ["12.4 Integrated Rate Laws\n614\n"]], ["block_11", ["12.5 Collision Theory\n625\n"]], ["block_12", ["12.6 Reaction Mechanisms\n630\n"]], ["block_13", ["12.7 Catalysis\n635\n"]], ["block_14", ["Key Terms\n642\n"]], ["block_15", ["Key Equations\n642\n"]], ["block_16", ["Summary\n643\n"]], ["block_17", ["Exercises\n644\n"]], ["block_18", ["CHAPTER 13\n Fundamental Equilibrium Concepts \n657\n"]], ["block_19", ["Introduction\n657\n"]], ["block_20", ["13.1 Chemical Equilibria\n657\n"]], ["block_21", ["13.2 Equilibrium Constants\n660\n"]], ["block_22", ["13.3 Shifting Equilibria: Le Ch\u00e2telier\u2019s Principle\n669\n"]], ["block_23", ["13.4 Equilibrium Calculations\n675\n"]], ["block_24", ["Key Terms\n683\n"]], ["block_25", ["Key Equations\n683\n"]], ["block_26", ["Summary\n683\n"]], ["block_27", ["Exercises\n684\n"]], ["block_28", ["CHAPTER 14\n Acid-Base Equilibria \n693\n"]], ["block_29", ["Introduction\n693\n"]], ["block_30", ["14.1 Br\u00f8nsted-Lowry Acids and Bases\n693\n"]], ["block_31", ["14.2 pH and pOH\n697\n"]], ["block_32", ["14.3 Relative Strengths of Acids and Bases\n702\n"]], ["block_33", ["14.4 Hydrolysis of Salts\n716\n"]], ["block_34", ["14.5 Polyprotic Acids\n721\n"]], ["block_35", ["14.6 Buffers\n724\n"]], ["block_36", ["14.7 Acid-Base Titrations\n730\n"]], ["block_37", ["Key Terms\n738\n"]], ["block_38", ["Key Equations\n738\n"]], ["block_39", ["Summary\n739\n"]], ["block_40", ["Exercises\n740\n"]], ["block_41", [" Access for free at openstax.org \n"]]], "page_10": [["block_0", ["CHAPTER 15\n Equilibria of Other Reaction Classes \n749\n"]], ["block_1", ["Introduction\n749\n"]], ["block_2", ["15.1 Precipitation and Dissolution\n749\n"]], ["block_3", ["15.2 Lewis Acids and Bases\n763\n"]], ["block_4", ["15.3 Coupled Equilibria\n767\n"]], ["block_5", ["Key Terms\n772\n"]], ["block_6", ["Key Equations\n772\n"]], ["block_7", ["Summary\n772\n"]], ["block_8", ["Exercises\n773\n"]], ["block_9", ["CHAPTER 16\n Thermodynamics \n783\n"]], ["block_10", ["Introduction\n783\n"]], ["block_11", ["16.1 Spontaneity\n783\n"]], ["block_12", ["16.2 Entropy\n787\n"]], ["block_13", ["16.3 The Second and Third Laws of Thermodynamics\n793\n"]], ["block_14", ["16.4 Free Energy\n797\n"]], ["block_15", ["Key Terms\n809\n"]], ["block_16", ["Key Equations\n809\n"]], ["block_17", ["Summary\n809\n"]], ["block_18", ["Exercises\n810\n"]], ["block_19", ["CHAPTER 17\n Electrochemistry \n817\n"]], ["block_20", ["Introduction\n817\n"]], ["block_21", ["17.1 Review of Redox Chemistry\n818\n"]], ["block_22", ["17.2 Galvanic Cells\n821\n"]], ["block_23", ["17.3 Electrode and Cell Potentials\n824\n"]], ["block_24", ["17.4 Potential, Free Energy, and Equilibrium\n830\n"]], ["block_25", ["17.5 Batteries and Fuel Cells\n834\n"]], ["block_26", ["17.6 Corrosion\n840\n"]], ["block_27", ["17.7 Electrolysis\n843\n"]], ["block_28", ["Key Terms\n849\n"]], ["block_29", ["Key Equations\n850\n"]], ["block_30", ["Summary\n850\n"]], ["block_31", ["Exercises\n851\n"]], ["block_32", ["CHAPTER 18\n Representative Metals, Metalloids, and Nonmetals \n857\n"]], ["block_33", ["Introduction\n857\n"]], ["block_34", ["18.1 Periodicity\n858\n"]], ["block_35", ["18.2 Occurrence and Preparation of the Representative Metals\n867\n"]], ["block_36", ["18.3 Structure and General Properties of the Metalloids\n870\n"]], ["block_37", ["18.4 Structure and General Properties of the Nonmetals\n877\n"]], ["block_38", ["18.5 Occurrence, Preparation, and Compounds of Hydrogen\n885\n"]], ["block_39", ["18.6 Occurrence, Preparation, and Properties of Carbonates\n891\n"]], ["block_40", ["18.7 Occurrence, Preparation, and Properties of Nitrogen\n893\n"]], ["block_41", ["18.8 Occurrence, Preparation, and Properties of Phosphorus\n897\n"]]], "page_11": [["block_0", ["18.9 Occurrence, Preparation, and Compounds of Oxygen\n899\n"]], ["block_1", ["18.10 Occurrence, Preparation, and Properties of Sulfur\n913\n"]], ["block_2", ["18.11 Occurrence, Preparation, and Properties of Halogens\n915\n"]], ["block_3", ["18.12 Occurrence, Preparation, and Properties of the Noble Gases\n920\n"]], ["block_4", ["Key Terms\n922\n"]], ["block_5", ["Summary\n923\n"]], ["block_6", ["Exercises\n924\n"]], ["block_7", ["CHAPTER 19\n Transition Metals and Coordination Chemistry \n935\n"]], ["block_8", ["Introduction\n935\n"]], ["block_9", ["19.1 Occurrence, Preparation, and Properties of Transition Metals and Their Compounds\n935\n"]], ["block_10", ["19.2 Coordination Chemistry of Transition Metals\n948\n"]], ["block_11", ["19.3 Spectroscopic and Magnetic Properties of Coordination Compounds\n962\n"]], ["block_12", ["Key Terms\n971\n"]], ["block_13", ["Summary\n972\n"]], ["block_14", ["Exercises\n973\n"]], ["block_15", ["CHAPTER 20\n Organic Chemistry \n977\n"]], ["block_16", ["Introduction\n977\n"]], ["block_17", ["20.1 Hydrocarbons\n978\n"]], ["block_18", ["20.2 Alcohols and Ethers\n995\n"]], ["block_19", ["20.3 Aldehydes, Ketones, Carboxylic Acids, and Esters\n999\n"]], ["block_20", ["20.4 Amines and Amides\n1005\n"]], ["block_21", ["Key Terms\n1014\n"]], ["block_22", ["Summary\n1014\n"]], ["block_23", ["Exercises\n1015\n"]], ["block_24", ["CHAPTER 21\n Nuclear Chemistry \n1021\n"]], ["block_25", ["Introduction\n1021\n"]], ["block_26", ["21.1 Nuclear Structure and Stability\n1022\n"]], ["block_27", ["21.2 Nuclear Equations\n1028\n"]], ["block_28", ["21.3 Radioactive Decay\n1031\n"]], ["block_29", ["21.4 Transmutation and Nuclear Energy\n1042\n"]], ["block_30", ["21.5 Uses of Radioisotopes\n1055\n"]], ["block_31", ["21.6 Biological Effects of Radiation\n1059\n"]], ["block_32", ["Key Terms\n1067\n"]], ["block_33", ["Key Equations\n1068\n"]], ["block_34", ["Summary\n1069\n"]], ["block_35", ["Exercises\n1070\n"]], ["block_36", [" Appendix A The Periodic Table\n1077\n"]], ["block_37", [" Appendix B Essential Mathematics\n1079\n"]], ["block_38", [" Appendix C Units and Conversion Factors\n1087\n"]], ["block_39", [" Appendix D Fundamental Physical Constants\n1091\n"]], ["block_40", [" Access for free at openstax.org \n"]]], "page_12": [["block_0", [" Appendix E Water Properties\n1093\n"]], ["block_1", [" Appendix F Composition of Commercial Acids and Bases\n1099\n"]], ["block_2", [" Appendix G Standard Thermodynamic Properties for Selected Substances\n1101\n"]], ["block_3", [" Appendix H Ionization Constants of Weak Acids\n1119\n"]], ["block_4", [" Appendix I Ionization Constants of Weak Bases\n1123\n"]], ["block_5", [" Appendix J Solubility Products\n1125\n"]], ["block_6", [" Appendix K Formation Constants for Complex Ions\n1131\n"]], ["block_7", [" Appendix L Standard Electrode (Half-Cell) Potentials\n1133\n"]], ["block_8", [" Appendix M Half-Lives for Several Radioactive Isotopes\n1139\n"]], ["block_9", ["Answer Key\n1141\n"]], ["block_10", ["Index\n1201\n"]]], "page_13": [["block_0", [" Access for free at openstax.org \n"]]], "page_14": [["block_0", [" Customization \nChemistry 2e is licensed under a Creative Commons Attribution 4.0 International (CC BY) license, which\nmeans that you can distribute, remix, and build upon the content, as long as you provide attribution to\nOpenStax and its content contributors.\n"]], ["block_1", ["Chemistry 2e is designed to meet the scope and sequence requirements of the two-semester general\nchemistry course. The textbook provides an important opportunity for students to learn the core concepts of\nchemistry and understand how those concepts apply to their lives and the world around them. The book also\nincludes a number of innovative features, including interactive exercises and real-world applications,\ndesigned to enhance student learning. The second edition has been revised to incorporate clearer, more\ncurrent, and more dynamic explanations, while maintaining the same organization as the first edition.\nSubstantial improvements have been made in the figures, illustrations, and example exercises that support the\ntext narrative.\n"]], ["block_2", [" PREFACE \n"]], ["block_3", ["Welcome to Chemistry 2e, an OpenStax resource. This textbook was written to increase student access to high-\nquality learning materials, maintaining highest standards of academic rigor at little to no cost.\n"]], ["block_4", [" About OpenStax \n"]], ["block_5", ["OpenStax is a nonprofit based at Rice University, and it\u2019s our mission to improve student access to education.\nOur first openly licensed college textbook was published in 2012, and our library has since scaled to over 25\nbooks for college and APcourses used by hundreds of thousands of students. OpenStax Tutor, our low-cost\npersonalized learning tool, is being used in college courses throughout the country. Through our partnerships\nwith philanthropic foundations and our alliance with other educational resource organizations, OpenStax is\nbreaking down the most common barriers to learning and empowering students and instructors to succeed.\n"]], ["block_6", [" About OpenStax resources \n"]], ["block_7", ["Because our books are openly licensed, you are free to use the entire book or pick and choose the sections that\nare most relevant to the needs of your course. Feel free to remix the content by assigning your students certain\nchapters and sections in your syllabus, in the order that you prefer. You can even provide a direct link in your\nsyllabus to the sections in the web view of your book.\n"]], ["block_8", ["Instructors also have the option of creating a customized version of their OpenStax book. The custom version\ncan be made available to students in low-cost print or digital form through their campus bookstore. Visit the\nInstructor Resources section of your book page on OpenStax.org for more information.\n"]], ["block_9", [" Errata \nAll OpenStax textbooks undergo a rigorous review process. However, like any professional-grade textbook,\nerrors sometimes occur. Since our books are web based, we can make updates periodically when deemed\npedagogically necessary. If you have a correction to suggest, submit it through the link on your book page on\nOpenStax.org. Subject matter experts review all errata suggestions. OpenStax is committed to remaining\ntransparent about all updates, so you will also find a list of past errata changes on your book page on\nOpenStax.org.\n"]], ["block_10", [" Format \nYou can access this textbook for free in web view or PDF through OpenStax.org, and for a low cost in print.\n"]], ["block_11", [" About Chemistry 2e \n"]], ["block_12", [" Coverage and scope \nOur Chemistry 2e textbook adheres to the scope and sequence of most general chemistry courses nationwide.\nWe strive to make chemistry, as a discipline, interesting and accessible to students. With this objective in\n"]], ["block_13", [" Preface \n 1 \n"]]], "page_15": [["block_0", [" 2 \n Preface \n"]], ["block_1", ["mind, the content of this textbook has been developed and arranged to provide a logical progression from\nfundamental to more advanced concepts of chemical science. Topics are introduced within the context of\nfamiliar experiences whenever possible, treated with an appropriate rigor to satisfy the intellect of the learner,\nand reinforced in subsequent discussions of related content. The organization and pedagogical features were\ndeveloped and vetted with feedback from chemistry educators dedicated to the project.\n"]], ["block_2", [" Changes to the second edition \nOpenStax only undertakes second editions when significant modifications to the text are necessary. In the case\nof Chemistry 2e, user feedback indicated that we needed to focus on a few key areas, which we have done in\nthe following ways:\n"]], ["block_3", [" Content revisions for clarity and accuracy. The revision plan varied by chapter based on need. About five\nchapters were extensively rewritten and another twelve chapters were substantially revised to improve the\nreadability and clarity of the narrative.\n"]], ["block_4", [" Example and end-of-chapter exercises. The example and end-of-chapter exercises in several chapters were\nsubjected to a rigorous accuracy check and revised to correct any errors, and additional exercises were added\nto several chapters to more fully support chapter content.\n"]], ["block_5", [" Art and illustrations. Under the guidance of the authors and expert scientific illustrators, especially those\nwell-versed in creating accessible art, the OpenStax team made changes to much of the art in the first edition\nof Chemistry. The revisions included correcting errors, redesigning illustrations to improve understanding,\nand recoloring for overall consistency.\n"]], ["block_6", [" Accessibility improvements. As with all OpenStax books, the first edition of Chemistry was created with a\nfocus on accessibility. We have emphasized and improved that approach in the second edition. To\naccommodate users of specific assistive technologies, all alternative text was reviewed and revised for\ncomprehensiveness and clarity. Many illustrations were revised to improve the color contrast, which is\nimportant for some visually impaired students. Overall, the OpenStax platform has been continually upgraded\nto improve accessibility.\n"]], ["block_7", [" Pedagogical foundation and features \nThroughout Chemistry 2e, you will find features that draw the students into scientific inquiry by taking\nselected topics a step further. Students and educators alike will appreciate discussions in these feature boxes.\n"]], ["block_8", [" Comprehensive art program \nOur art program is designed to enhance students\u2019 understanding of concepts through clear, effective\nillustrations, diagrams, and photographs.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["\u2022\n Chemistry in Everyday Life ties chemistry concepts to everyday issues and real-world applications of\nscience that students encounter in their lives. Topics include cell phones, solar thermal energy power\nplants, plastics recycling, and measuring blood pressure.\n"]], ["block_11", ["\u2022\n How Sciences Interconnect feature boxes discuss chemistry in context of its interconnectedness with\nother scientific disciplines. Topics include neurotransmitters, greenhouse gases and climate change, and\nproteins and enzymes.\n"]], ["block_12", ["\u2022\n Portrait of a Chemist presents a short bio and an introduction to the work of prominent figures from\nhistory and present day so that students can see the \u201cfaces\u201d of contributors in this field as well as science\nin action.\n"]]], "page_16": [["block_0", [{"image_0": "16_0.png", "coords": [72, 57, 540, 173]}]], ["block_1", [{"image_1": "16_1.png", "coords": [72, 176, 540, 381]}]], ["block_2", [{"image_2": "16_2.png", "coords": [72, 384, 423, 584]}]], ["block_3", [{"image_3": "16_3.png", "coords": [72, 586, 540, 710]}]], ["block_4", [" Preface \n 3 \n"]]], "page_17": [["block_0", [" 4 \n Preface \n"]], ["block_1", [" Interactives that engage \nChemistry 2e incorporates links to relevant interactive exercises and animations that help bring topics to life\nthrough our Link to Learning feature. Examples include:\n"]], ["block_2", [{"image_0": "17_0.png", "coords": [72, 57, 540, 275]}]], ["block_3", [{"image_1": "17_1.png", "coords": [72, 277, 423, 405]}]], ["block_4", [{"image_2": "17_2.png", "coords": [72, 408, 423, 533]}]], ["block_5", [" Assessments that reinforce key concepts \nIn-chapter Examples walk students through problems by posing a question, stepping out a solution, and then\nasking students to practice the skill with a \u201cCheck Your Learning\u201d component. The book also includes\nassessments at the end of each chapter so students can apply what they\u2019ve learned through practice problems.\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", ["\u2022\nPhET simulations\n"]], ["block_8", ["\u2022\nIUPAC data and interactives\n"]], ["block_9", ["\u2022\nTED Talks\n"]]], "page_18": [["block_0", [" Additional resources \n"]], ["block_1", [" Student and instructor resources \nWe\u2019ve compiled additional resources for both students and instructors, including Getting Started Guides, an\ninstructor solutions manual, and PowerPoint slides. Instructor resources require a verified instructor account,\nwhich you can apply for when you log in or create your account on OpenStax.org. Take advantage of these\nresources to supplement your OpenStax book.\n"]], ["block_2", [" Community Hubs \nOpenStax partners with the Institute for the Study of Knowledge Management in Education (ISKME) to offer\n Community Hubs on OER Commons \u2014 a platform for instructors to share community-created resources that\nsupport OpenStax books, free of charge. Through our Community Hubs , instructors can upload their own\nmaterials or download resources to use in their own courses, including additional ancillaries, teaching\nmaterial, multimedia, and relevant course content. We encourage instructors to join the hubs for the subjects\nmost relevant to your teaching and research as an opportunity both to enrich your courses and to engage with\nother faculty.\n"]], ["block_3", ["To reach the Community Hubs, visit www.oercommons.org/hubs/OpenStax (https://www.oercommons.org/\nhubs/OpenStax).\n"]], ["block_4", [" Technology partners \nAs allies in making high-quality learning materials accessible, our technology partners offer optional low-cost\ntools that are integrated with OpenStax books. To access the technology options for your text, visit your book\npage on OpenStax.org.\n"]], ["block_5", [" About the authors \n"]], ["block_6", [" Senior contributing authors \n Paul Flowers, University of North Carolina at Pembroke \nDr. Paul Flowers earned a BS in Chemistry from St. Andrews Presbyterian College in 1983 and a PhD in\nAnalytical Chemistry from the University of Tennessee in 1988. After a one-year postdoctoral appointment at\nLos Alamos National Laboratory, he joined the University of North Carolina at Pembroke in the fall of 1989. Dr.\nFlowers teaches courses in general and analytical chemistry, and conducts experimental research involving\nthe development of new devices and methods for microscale chemical analysis.\n"]], ["block_7", [" Klaus Theopold, University of Delaware \nDr. Klaus Theopold (born in Berlin, Germany) received his Vordiplom from the Universit\u00e4t Hamburg in 1977.\nHe then decided to pursue his graduate studies in the United States, where he received his PhD in inorganic\nchemistry from UC Berkeley in 1982. After a year of postdoctoral research at MIT, he joined the faculty at\nCornell University. In 1990, he moved to the University of Delaware, where he is a Professor in the Department\nof Chemistry and Biochemistry and serves as an Associate Director of the University\u2019s Center for Catalytic\nScience and Technology. Dr. Theopold regularly teaches graduate courses in inorganic and organometallic\nchemistry as well as general chemistry.\n"]], ["block_8", [" Richard Langley, Stephen F. Austin State University \nDr. Richard Langley earned BS degrees in Chemistry and Mineralogy from Miami University of Ohio in the\nearly 1970s and went on to receive his PhD in Chemistry from the University of Nebraska in 1977. After a\npostdoctoral fellowship at the Arizona State University Center for Solid State Studies, Dr. Langley taught in the\nUniversity of Wisconsin system and participated in research at Argonne National Laboratory. Moving to\nStephen F. Austin State University in 1982, Dr. Langley today serves as Professor of Chemistry. His areas of\nspecialization are solid state chemistry, synthetic inorganic chemistry, fluorine chemistry, and chemical\neducation.\n"]], ["block_9", [" William R. Robinson, PhD \n"]], ["block_10", [" Contributing authors \nMark Blaser, Shasta College\nSimon Bott, University of Houston\n"]], ["block_11", [" Preface \n 5 \n"]]], "page_19": [["block_0", [" 6 \n Preface \n"]], ["block_1", ["Donald Carpenetti, Craven Community College\nAndrew Eklund, Alfred University\nEmad El-Giar, University of Louisiana at Monroe\nDon Frantz, Wilfrid Laurier University\nPaul Hooker, Westminster College\nJennifer Look, Mercer University\nGeorge Kaminski, Worcester Polytechnic Institute\nCarol Martinez, Central New Mexico Community College\nTroy Milliken, Jackson State University\nVicki Moravec, Trine University\nJason Powell, Ferrum College\nThomas Sorensen, University of Wisconsin\u2013Milwaukee\nAllison Soult, University of Kentucky\n"]], ["block_2", [" Reviewers \nCasey Akin, College Station Independent School District\nLara AL-Hariri, University of Massachusetts\u2013Amherst\nSahar Atwa, University of Louisiana at Monroe\nTodd Austell, University of North Carolina\u2013Chapel Hill\nBobby Bailey, University of Maryland\u2013University College\nRobert Baker, Trinity College\nJeffrey Bartz, Kalamazoo College\nGreg Baxley, Cuesta College\nAshley Beasley Green, National Institute of Standards and Technology\nPatricia Bianconi, University of Massachusetts\nLisa Blank, Lyme Central School District\nDaniel Branan, Colorado Community College System\nDorian Canelas, Duke University\nEmmanuel Chang, York College\nCarolyn Collins, College of Southern Nevada\nColleen Craig, University of Washington\nYasmine Daniels, Montgomery College\u2013Germantown\nPatricia Dockham, Grand Rapids Community College\nErick Fuoco, Richard J. Daley College\nAndrea Geyer, University of Saint Francis\nDaniel Goebbert, University of Alabama\nJohn Goodwin, Coastal Carolina University\nStephanie Gould, Austin College\nPatrick Holt, Bellarmine University\nGeorge A. Kaminski, Worcester Polytechnic Institute\nKevin Kolack, Queensborough Community College\nAmy Kovach, Roberts Wesleyan College\nJudit Kovacs Beagle, University of Dayton\nKrzysztof Kuczera, University of Kansas\nMarcus Lay, University of Georgia\nPamela Lord, University of Saint Francis\nOleg Maksimov, Excelsior College\nJohn Matson, Virginia Tech\nKatrina Miranda, University of Arizona\nDouglas Mulford, Emory University\nMark Ott, Jackson College\nAdrienne Oxley, Columbia College\nRichard Pennington, Georgia Gwinnett College\nRodney Powell, Coastal Carolina Community College\n"]], ["block_3", [" Access for free at openstax.org \n"]]], "page_20": [["block_0", ["Jeanita Pritchett, Montgomery College\u2013Rockville\nAheda Saber, University of Illinois at Chicago\nRaymond Sadeghi, University of Texas at San Antonio\nNirmala Shankar, Rutgers University\nJonathan Smith, Temple University\nBryan Spiegelberg, Rider University\nRon Sternfels, Roane State Community College\nCynthia Strong, Cornell College\nKris Varazo, Francis Marion University\nVictor Vilchiz, Virginia State University\nAlex Waterson, Vanderbilt University\nJuchaoYan, Eastern New Mexico University\nMustafa Yatin, Salem State University\nKazushige Yokoyama, State University of New York at Geneseo\nCurtis Zaleski, Shippensburg University\nWei Zhang, University of Colorado\u2013Boulder\n"]], ["block_1", [" Preface \n 7 \n"]]], "page_21": [["block_0", [" 8 \n Preface \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_22": [["block_0", ["CHAPTER 1\nEssential Ideas\n"]], ["block_1", [{"image_0": "22_0.png", "coords": [72, 104, 622, 220]}]], ["block_2", [" Figure 1.1 \nChemical substances and processes are essential for our existence, providing sustenance, keeping us\n"]], ["block_3", ["clean and healthy, fabricating electronic devices, enabling transportation, and much more. (credit \u201cleft\u201d:\nmodification of work by \u201cvxla\u201d/Flickr; credit \u201cleft middle\u201d: modification of work by \u201cthe Italian voice\u201d/Flickr; credit\n\u201cright middle\u201d: modification of work by Jason Trim; credit \u201cright\u201d: modification of work by \u201cgosheshe\u201d/Flickr)\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 1.1 Chemistry in Context \n 1.2 Phases and Classification of Matter \n 1.3 Physical and Chemical Properties \n 1.4 Measurements \n 1.5 Measurement Uncertainty, Accuracy, and Precision \n 1.6 Mathematical Treatment of Measurement Results \n"]], ["block_6", [" INTRODUCTION \n"]], ["block_7", ["make a cup of coffee to help you get going, and then you shower, get dressed, eat breakfast, and check your\nphone for messages. On your way to school, you stop to fill your car\u2019s gas tank, almost making you late for the\nfirst day of chemistry class. As you find a seat in the classroom, you read the question projected on the screen:\n\u201cWelcome to class! Why should we study chemistry?\u201d\n"]], ["block_8", ["Do you have an answer? You may be studying chemistry because it fulfills an academic requirement, but if you\nconsider your daily activities, you might find chemistry interesting for other reasons. Most everything you do\nand encounter during your day involves chemistry. Making coffee, cooking eggs, and toasting bread involve\nchemistry. The products you use\u2014like soap and shampoo, the fabrics you wear, the electronics that keep you\nconnected to your world, the gasoline that propels your car\u2014all of these and more involve chemical substances\nand processes. Whether you are aware or not, chemistry is part of your everyday world. In this course, you will\nlearn many of the essential principles underlying the chemistry of modern-day life.\n"]], ["block_9", [" 1.1 Chemistry in Context \n"]], ["block_10", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_11", ["Throughout human history, people have tried to convert matter into more useful forms. Our Stone Age\n"]], ["block_12", ["\u2022\nOutline the historical development of chemistry\n"]], ["block_13", ["\u2022\nProvide examples of the importance of chemistry in everyday life\n"]], ["block_14", ["\u2022\nDescribe the scientific method\n"]], ["block_15", ["\u2022\nDifferentiate among hypotheses, theories, and laws\n"]], ["block_16", ["\u2022\nProvide examples illustrating macroscopic, microscopic, and symbolic domains\n"]], ["block_17", ["Your alarm goes off and, after hitting \u201csnooze\u201d once or twice, you pry yourself out of bed. You\n"]]], "page_23": [["block_0", [" 10 \n 1 \u2022 Essential Ideas \n"]], ["block_1", ["ancestors chipped pieces of flint into useful tools and carved wood into statues and toys. These endeavors\ninvolved changing the shape of a substance without changing the substance itself. But as our knowledge\nincreased, humans began to change the composition of the substances as well\u2014clay was converted into\npottery, hides were cured to make garments, copper ores were transformed into copper tools and weapons,\nand grain was made into bread.\n"]], ["block_2", ["Humans began to practice chemistry when they learned to control fire and use it to cook, make pottery, and\nsmelt metals. Subsequently, they began to separate and use specific components of matter. A variety of drugs\nsuch as aloe, myrrh, and opium were isolated from plants. Dyes, such as indigo and Tyrian purple, were\nextracted from plant and animal matter. Metals were combined to form alloys\u2014for example, copper and tin\nwere mixed together to make bronze\u2014and more elaborate smelting techniques produced iron. Alkalis were\nextracted from ashes, and soaps were prepared by combining these alkalis with fats. Alcohol was produced by\nfermentation and purified by distillation.\n"]], ["block_3", ["Attempts to understand the behavior of matter extend back for more than 2500 years. As early as the sixth\ncentury BC, Greek philosophers discussed a system in which water was the basis of all things. You may have\nheard of the Greek postulate that matter consists of four elements: earth, air, fire, and water. Subsequently, an\namalgamation of chemical technologies and philosophical speculations was spread from Egypt, China, and the\neastern Mediterranean by alchemists, who endeavored to transform \u201cbase metals\u201d such as lead into \u201cnoble\nmetals\u201d like gold, and to create elixirs to cure disease and extend life (Figure 1.2).\n"]], ["block_4", [{"image_0": "23_0.png", "coords": [72, 303, 544, 486]}]], ["block_5", [" FIGURE 1.2 \n(a) This portrayal shows an alchemist\u2019s workshop circa 1580. Although alchemy made some useful\n"]], ["block_6", ["contributions to how to manipulate matter, it was not scientific by modern standards. (b) While the equipment used\nby Alma Levant Hayden in this 1952 picture might not seem as sleek as you might find in a lab today, her approach\nwas highly methodical and carefully recorded. A department head at the FDA, Hayden is most famous for exposing\nan aggressively marketed anti-cancer drug as nothing more than an unhelpful solution of common substances.\n(credit a: Chemical Heritage Foundation; b: NIH History Office)\n"]], ["block_7", ["From alchemy came the historical progressions that led to modern chemistry: the isolation of drugs from\nnatural sources, such as plants and animals. But while many of the substances extracted or processed from\nthose natural sources were critical in the treatment of diseases, many were scarce. For example, progesterone,\nwhich is critical to women's health, became available as a medicine in 1935, but its animal sources produced\nextremely small quantities, limiting its availability and increasing its expense. Likewise, in the 1940s,\ncortisone came into use to treat arthritis and other disorders and injuries, but it took a 36-step process to\nsynthesize. Chemist Percy Lavon Julian turned to a more plentiful source: soybeans. Previously, Julian had\ndeveloped a lab to isolate soy protein, which was used in firefighting among other applications. He focused on\nusing the soy sterols\u2014substances mostly used in plant membranes\u2014and was able to quickly produce\nprogesterone and later testosterone and other hormones. He later developed a process to do the same for\ncortisone, and laid the groundwork for modern drug design. Since soybeans and similar plant sources were\nextremely plentiful, the drugs soon became widely available, saving many lives.\n"]], ["block_8", [" Access for free at openstax.org \n"]]], "page_24": [["block_0", [" Chemistry: The Central Science \n"]], ["block_1", ["Chemistry is sometimes referred to as \u201cthe central science\u201d due to its interconnectedness with a vast array of\nother STEM disciplines (STEM stands for areas of study in the science, technology, engineering, and math\nfields). Chemistry and the language of chemists play vital roles in biology, medicine, materials science,\nforensics, environmental science, and many other fields (Figure 1.3). The basic principles of physics are\nessential for understanding many aspects of chemistry, and there is extensive overlap between many\nsubdisciplines within the two fields, such as chemical physics and nuclear chemistry. Mathematics, computer\nscience, and information theory provide important tools that help us calculate, interpret, describe, and\ngenerally make sense of the chemical world. Biology and chemistry converge in biochemistry, which is crucial\nto understanding the many complex factors and processes that keep living organisms (such as us) alive.\nChemical engineering, materials science, and nanotechnology combine chemical principles and empirical\nfindings to produce useful substances, ranging from gasoline to fabrics to electronics. Agriculture, food\nscience, veterinary science, and brewing and wine making help provide sustenance in the form of food and\ndrink to the world\u2019s population. Medicine, pharmacology, biotechnology, and botany identify and produce\nsubstances that help keep us healthy. Environmental science, geology, oceanography, and atmospheric science\nincorporate many chemical ideas to help us better understand and protect our physical world. Chemical ideas\nare used to help understand the universe in astronomy and cosmology.\n"]], ["block_2", [{"image_0": "24_0.png", "coords": [72, 285, 540, 488]}]], ["block_3", [" FIGURE 1.3 \nKnowledge of chemistry is central to understanding a wide range of scientific disciplines. This diagram\n"]], ["block_4", ["shows just some of the interrelationships between chemistry and other fields.\n"]], ["block_5", ["What are some changes in matter that are essential to daily life? Digesting and assimilating food, synthesizing\npolymers that are used to make clothing, containers, cookware, and credit cards, and refining crude oil into\ngasoline and other products are just a few examples. As you proceed through this course, you will discover\nmany different examples of changes in the composition and structure of matter, how to classify these changes\nand how they occurred, their causes, the changes in energy that accompany them, and the principles and laws\ninvolved. As you learn about these things, you will be learning chemistry , the study of the composition,\nproperties, and interactions of matter. The practice of chemistry is not limited to chemistry books or\nlaboratories: It happens whenever someone is involved in changes in matter or in conditions that may lead to\nsuch changes.\n"]], ["block_6", [" The Scientific Method \n"]], ["block_7", ["Chemistry is a science based on observation and experimentation. Doing chemistry involves attempting to\nanswer questions and explain observations in terms of the laws and theories of chemistry, using procedures\nthat are accepted by the scientific community. There is no single route to answering a question or explaining\nan observation, but there is an aspect common to every approach: Each uses knowledge based on experiments\nthat can be reproduced to verify the results. Some routes involve a hypothesis , a tentative explanation of\n"]], ["block_8", [" 1.1 \u2022 Chemistry in Context \n 11 \n"]]], "page_25": [["block_0", [" 12 \n 1 \u2022 Essential Ideas \n"]], ["block_1", ["Macro is a Greek word that means \u201clarge.\u201d The macroscopic domain is familiar to us: It is the realm of\neveryday things that are large enough to be sensed directly by human sight or touch. In daily life, this includes\nthe food you eat and the breeze you feel on your face. The macroscopic domain includes everyday and\nlaboratory chemistry, where we observe and measure physical and chemical properties such as density,\nsolubility, and flammability.\n"]], ["block_2", ["Micro comes from Greek and means \u201csmall.\u201d The microscopic domain of chemistry is often visited in the\nimagination. Some aspects of the microscopic domain are visible through standard optical microscopes, for\nexample, many biological cells. More sophisticated instruments are capable of imaging even smaller entities\nsuch as molecules and atoms (see Figure 1.5 ( b )).\n"]], ["block_3", ["observations that acts as a guide for gathering and checking information. A hypothesis is tested by\nexperimentation, calculation, and/or comparison with the experiments of others and then refined as needed.\n"]], ["block_4", ["Some hypotheses are attempts to explain the behavior that is summarized in laws. The laws of science\nsummarize a vast number of experimental observations, and describe or predict some facet of the natural\nworld. If such a hypothesis turns out to be capable of explaining a large body of experimental data, it can reach\nthe status of a theory. Scientific theories are well-substantiated, comprehensive, testable explanations of\nparticular aspects of nature. Theories are accepted because they provide satisfactory explanations, but they\ncan be modified if new data become available. The path of discovery that leads from question and observation\nto law or hypothesis to theory, combined with experimental verification of the hypothesis and any necessary\nmodification of the theory, is called the scientific method (Figure 1.4).\n"]], ["block_5", [{"image_0": "25_0.png", "coords": [72, 196, 540, 471]}]], ["block_6", [" FIGURE 1.4 \nThe scientific method follows a process similar to the one shown in this diagram. All the key\n"]], ["block_7", ["components are shown, in roughly the right order. Scientific progress is seldom neat and clean: It requires open\ninquiry and the reworking of questions and ideas in response to findings.\n"]], ["block_8", [" The Domains of Chemistry \n"]], ["block_9", ["Chemists study and describe the behavior of matter and energy in three different domains: macroscopic,\nmicroscopic, and symbolic. These domains provide different ways of considering and describing chemical\nbehavior.\n"]], ["block_10", ["However, most of the subjects in the microscopic domain of chemistry are too small to be seen even with the\nmost advanced microscopes and may only be pictured in the mind. Other components of the microscopic\n"]], ["block_11", [" Access for free at openstax.org \n"]]], "page_26": [["block_0", ["domain include ions and electrons, protons and neutrons, and chemical bonds, each of which is far too small\nto see.\n"]], ["block_1", ["The symbolic domain contains the specialized language used to represent components of the macroscopic\nand microscopic domains. Chemical symbols (such as those used in the periodic table), chemical formulas,\nand chemical equations are part of the symbolic domain, as are graphs, drawings, and calculations. These\nsymbols play an important role in chemistry because they help interpret the behavior of the macroscopic\ndomain in terms of the components of the microscopic domain. One of the challenges for students learning\nchemistry is recognizing that the same symbols can represent different things in the macroscopic and\nmicroscopic domains, and one of the features that makes chemistry fascinating is the use of a domain that\nmust be imagined to explain behavior in a domain that can be observed.\n"]], ["block_2", ["A helpful way to understand the three domains is via the essential and ubiquitous substance of water. That\nwater is a liquid at moderate temperatures, will freeze to form a solid at lower temperatures, and boil to form a\ngas at higher temperatures (Figure 1.5) are macroscopic observations. But some properties of water fall into\nthe microscopic domain\u2014what cannot be observed with the naked eye. The description of water as comprising\ntwo hydrogen atoms and one oxygen atom, and the explanation of freezing and boiling in terms of attractions\nbetween these molecules, is within the microscopic arena. The formula H2O, which can describe water at\neither the macroscopic or microscopic levels, is an example of the symbolic domain. The abbreviations (g) for\ngas, (s) for solid, and (l) for liquid are also symbolic.\n"]], ["block_3", [{"image_0": "26_0.png", "coords": [72, 303, 540, 562]}]], ["block_4", [" FIGURE 1.5 \n(a) Moisture in the air, icebergs, and the ocean represent water in the macroscopic domain. (b) At the\n"]], ["block_5", ["molecular level (microscopic domain), gas molecules are far apart and disorganized, solid water molecules are close\ntogether and organized, and liquid molecules are close together and disorganized. (c) The formula H2O symbolizes\nwater, and (g), (s), and (l) symbolize its phases. Note that clouds are actually comprised of either very small liquid\nwater droplets or solid water crystals; gaseous water in our atmosphere is not visible to the naked eye, although it\nmay be sensed as humidity. (credit a: modification of work by \u201cGorkaazk\u201d/Wikimedia Commons)\n"]], ["block_6", [" 1.1 \u2022 Chemistry in Context \n 13 \n"]]], "page_27": [["block_0", [" 14 \n 1 \u2022 Essential Ideas \n"]], ["block_1", [" 1.2 Phases and Classification of Matter \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", [" Matter is defined as anything that occupies space and has mass, and it is all around us. Solids and liquids are\nmore obviously matter: We can see that they take up space, and their weight tells us that they have mass. Gases\nare also matter; if gases did not take up space, a balloon would not inflate (increase its volume) when filled with\ngas.\n"]], ["block_4", ["Solids, liquids, and gases are the three states of matter commonly found on earth (Figure 1.6). A solid is rigid\nand possesses a definite shape. A liquid flows and takes the shape of its container, except that it forms a flat or\nslightly curved upper surface when acted upon by gravity. (In zero gravity, liquids assume a spherical shape.)\nBoth liquid and solid samples have volumes that are very nearly independent of pressure. A gas takes both the\nshape and volume of its container.\n"]], ["block_5", [{"image_0": "27_0.png", "coords": [72, 317, 540, 540]}]], ["block_6", ["A fourth state of matter, plasma, occurs naturally in the interiors of stars. A plasma is a gaseous state of matter\nthat contains appreciable numbers of electrically charged particles (Figure 1.7). The presence of these charged\nparticles imparts unique properties to plasmas that justify their classification as a state of matter distinct from\ngases. In addition to stars, plasmas are found in some other high-temperature environments (both natural and\nman-made), such as lightning strikes, certain television screens, and specialized analytical instruments used\nto detect trace amounts of metals.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", ["\u2022\nDescribe the basic properties of each physical state of matter: solid, liquid, and gas\n"]], ["block_9", ["\u2022\nDistinguish between mass and weight\n"]], ["block_10", ["\u2022\nApply the law of conservation of matter\n"]], ["block_11", ["\u2022\nClassify matter as an element, compound, homogeneous mixture, or heterogeneous mixture with regard to its\nphysical state and composition\n"]], ["block_12", ["\u2022\nDefine and give examples of atoms and molecules\n"]], ["block_13", [" FIGURE 1.6 \nThe three most common states or phases of matter are solid, liquid, and gas.\n"]]], "page_28": [["block_0", ["The law of conservation of matter summarizes many scientific observations about matter: It states that there\nis no detectable change in the total quantity of matter present when matter converts from one type to another\n(a chemical change) or changes among solid, liquid, or gaseous states (a physical change). Brewing beer and\nthe operation of batteries provide examples of the conservation of matter (Figure 1.8). During the brewing of\nbeer, the ingredients (water, yeast, grains, malt, hops, and sugar) are converted into beer (water, alcohol,\ncarbonation, and flavoring substances) with no actual loss of substance. This is most clearly seen during the\nbottling process, when glucose turns into ethanol and carbon dioxide, and the total mass of the substances\ndoes not change. This can also be seen in a lead-acid car battery: The original substances (lead, lead oxide, and\nsulfuric acid), which are capable of producing electricity, are changed into other substances (lead sulfate and\nwater) that do not produce electricity, with no change in the actual amount of matter.\n"]], ["block_1", ["In a tiny cell in a plasma television, the plasma emits ultraviolet light, which in turn causes the display at that\nlocation to appear a specific color. The composite of these tiny dots of color makes up the image that you see.\nWatch this video (http://openstax.org/l/16plasma) to learn more about plasma and the places you encounter it.\n"]], ["block_2", ["Some samples of matter appear to have properties of solids, liquids, and/or gases at the same time. This can\noccur when the sample is composed of many small pieces. For example, we can pour sand as if it were a liquid\nbecause it is composed of many small grains of solid sand. Matter can also have properties of more than one\nstate when it is a mixture, such as with clouds. Clouds appear to behave somewhat like gases, but they are\nactually mixtures of air (gas) and tiny particles of water (liquid or solid).\n"]], ["block_3", ["The mass of an object is a measure of the amount of matter in it. One way to measure an object\u2019s mass is to\nmeasure the force it takes to accelerate the object. It takes much more force to accelerate a car than a bicycle\nbecause the car has much more mass. A more common way to determine the mass of an object is to use a\nbalance to compare its mass with a standard mass.\n"]], ["block_4", ["Although weight is related to mass, it is not the same thing. Weight refers to the force that gravity exerts on an\nobject. This force is directly proportional to the mass of the object. The weight of an object changes as the force\nof gravity changes, but its mass does not. An astronaut\u2019s mass does not change just because she goes to the\nmoon. But her weight on the moon is only one-sixth her earth-bound weight because the moon\u2019s gravity is only\none-sixth that of the earth\u2019s. She may feel \u201cweightless\u201d during her trip when she experiences negligible\nexternal forces (gravitational or any other), although she is, of course, never \u201cmassless.\u201d\n"]], ["block_5", ["LINK TO LEARNING\n"]], ["block_6", [" FIGURE 1.7 \nA plasma torch can be used to cut metal. (credit: \u201cHypertherm\u201d/Wikimedia Commons)\n"]], ["block_7", [{"image_0": "28_0.png", "coords": [189, 57, 423, 241]}]], ["block_8", [" 1.2 \u2022 Phases and Classification of Matter \n 15 \n"]]], "page_29": [["block_0", [" 16 \n 1 \u2022 Essential Ideas \n"]], ["block_1", [{"image_0": "29_0.png", "coords": [72, 57, 540, 278]}]], ["block_2", [" FIGURE 1.8 \n(a) The mass of beer precursor materials is the same as the mass of beer produced: Sugar has\n"]], ["block_3", ["become alcohol and carbon dioxide. (b) The mass of the lead, lead oxide, and sulfuric acid consumed by the\nproduction of electricity is exactly equal to the mass of lead sulfate and water that is formed.\n"]], ["block_4", ["Although this conservation law holds true for all conversions of matter, convincing examples are few and far\nbetween because, outside of the controlled conditions in a laboratory, we seldom collect all of the material that\nis produced during a particular conversion. For example, when you eat, digest, and assimilate food, all of the\nmatter in the original food is preserved. But because some of the matter is incorporated into your body, and\nmuch is excreted as various types of waste, it is challenging to verify by measurement.\n"]], ["block_5", [" Classifying Matter \n"]], ["block_6", ["Matter can be classified into several categories. Two broad categories are mixtures and pure substances. A\n pure substance has a constant composition. All specimens of a pure substance have exactly the same makeup\nand properties. Any sample of sucrose (table sugar) consists of 42.1% carbon, 6.5% hydrogen, and 51.4%\noxygen by mass. Any sample of sucrose also has the same physical properties, such as melting point, color, and\nsweetness, regardless of the source from which it is isolated.\n"]], ["block_7", ["Pure substances may be divided into two classes: elements and compounds. Pure substances that cannot be\nbroken down into simpler substances by chemical changes are called elements . Iron, silver, gold, aluminum,\nsulfur, oxygen, and copper are familiar examples of the more than 100 known elements, of which about 90\noccur naturally on the earth, and two dozen or so have been created in laboratories.\n"]], ["block_8", ["Pure substances that are comprised of two or more elements are called compounds . Compounds may be\nbroken down by chemical changes to yield either elements or other compounds, or both. Mercury(II) oxide, an\norange, crystalline solid, can be broken down by heat into the elements mercury and oxygen (Figure 1.9).\nWhen heated in the absence of air, the compound sucrose is broken down into the element carbon and the\ncompound water. (The initial stage of this process, when the sugar is turning brown, is known as\ncaramelization\u2014this is what imparts the characteristic sweet and nutty flavor to caramel apples, caramelized\nonions, and caramel). Silver(I) chloride is a white solid that can be broken down into its elements, silver and\nchlorine, by absorption of light. This property is the basis for the use of this compound in photographic films\nand photochromic eyeglasses (those with lenses that darken when exposed to light).\n"]], ["block_9", [" Access for free at openstax.org \n"]]], "page_30": [["block_0", [" FIGURE 1.9 \n(a) The compound mercury(II) oxide, (b) when heated, (c) decomposes into silvery droplets of liquid\n"]], ["block_1", ["mercury and invisible oxygen gas. (credit: modification of work by Paul Flowers)\n"]], ["block_2", ["Many compounds break down when heated. This site (http://openstax.org/l/16mercury) shows the breakdown\nof mercury oxide, HgO. You can also view an example of the photochemical decomposition of silver chloride\n(http://openstax.org/l/16silvchloride) (AgCl), the basis of early photography.\n"]], ["block_3", ["The properties of combined elements are different from those in the free, or uncombined, state. For example,\nwhite crystalline sugar (sucrose) is a compound resulting from the chemical combination of the element\ncarbon, which is a black solid in one of its uncombined forms, and the two elements hydrogen and oxygen,\nwhich are colorless gases when uncombined. Free sodium, an element that is a soft, shiny, metallic solid, and\nfree chlorine, an element that is a yellow-green gas, combine to form sodium chloride (table salt), a compound\nthat is a white, crystalline solid.\n"]], ["block_4", ["A mixture is composed of two or more types of matter that can be present in varying amounts and can be\nseparated by physical changes, such as evaporation (you will learn more about this later). A mixture with a\ncomposition that varies from point to point is called a heterogeneous mixture . Italian dressing is an example\nof a heterogeneous mixture (Figure 1.10). Its composition can vary because it may be prepared from varying\namounts of oil, vinegar, and herbs. It is not the same from point to point throughout the mixture\u2014one drop\nmay be mostly vinegar, whereas a different drop may be mostly oil or herbs because the oil and vinegar\nseparate and the herbs settle. Other examples of heterogeneous mixtures are chocolate chip cookies (we can\nsee the separate bits of chocolate, nuts, and cookie dough) and granite (we can see the quartz, mica, feldspar,\nand more).\n"]], ["block_5", ["A homogeneous mixture , also called a solution , exhibits a uniform composition and appears visually the\nsame throughout. An example of a solution is a sports drink, consisting of water, sugar, coloring, flavoring, and\nelectrolytes mixed together uniformly (Figure 1.10). Each drop of a sports drink tastes the same because each\ndrop contains the same amounts of water, sugar, and other components. Note that the composition of a sports\ndrink can vary\u2014it could be made with somewhat more or less sugar, flavoring, or other components, and still\nbe a sports drink. Other examples of homogeneous mixtures include air, maple syrup, gasoline, and a solution\nof salt in water.\n"]], ["block_6", [" FIGURE 1.10 \n(a) Oil and vinegar salad dressing is a heterogeneous mixture because its composition is not uniform\n"]], ["block_7", ["throughout. (b) A commercial sports drink is a homogeneous mixture because its composition is uniform\nthroughout. (credit a \u201cleft\u201d: modification of work by John Mayer; credit a \u201cright\u201d: modification of work by Umberto\nSalvagnin; credit b \u201cleft: modification of work by Jeff Bedford)\n"]], ["block_8", ["LINK TO LEARNING\n"]], ["block_9", [{"image_0": "30_0.png", "coords": [130, 57, 481, 163]}]], ["block_10", [{"image_1": "30_1.png", "coords": [130, 572, 481, 676]}]], ["block_11", [" 1.2 \u2022 Phases and Classification of Matter \n 17 \n"]]], "page_31": [["block_0", [" 18 \n 1 \u2022 Essential Ideas \n"]], ["block_1", ["Although there are just over 100 elements, tens of millions of chemical compounds result from different\ncombinations of these elements. Each compound has a specific composition and possesses definite chemical\nand physical properties that distinguish it from all other compounds. And, of course, there are innumerable\nways to combine elements and compounds to form different mixtures. A summary of how to distinguish\nbetween the various major classifications of matter is shown in (Figure 1.11).\n"]], ["block_2", [{"image_0": "31_0.png", "coords": [72, 126, 540, 285]}]], ["block_3", [" FIGURE 1.11 \nDepending on its properties, a given substance can be classified as a homogeneous mixture, a\n"]], ["block_4", ["heterogeneous mixture, a compound, or an element.\n"]], ["block_5", ["Eleven elements make up about 99% of the earth\u2019s crust and atmosphere (Table 1.1). Oxygen constitutes\nnearly one-half and silicon about one-quarter of the total quantity of these elements. A majority of elements on\nearth are found in chemical combinations with other elements; about one-quarter of the elements are also\nfound in the free state.\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [" TABLE 1.1 \n"]], ["block_8", [" Element \n Symbol \n Percent Mass \n Element \n Symbol \n Percent Mass \n"]], ["block_9", ["oxygen\nO\n49.20\nchlorine\nCl\n0.19\n"]], ["block_10", ["silicon\nSi\n25.67\nphosphorus\nP\n0.11\n"]], ["block_11", ["aluminum\nAl\n7.50\nmanganese\nMn\n0.09\n"]], ["block_12", ["iron\nFe\n4.71\ncarbon\nC\n0.08\n"]], ["block_13", ["calcium\nCa\n3.39\nsulfur\nS\n0.06\n"]], ["block_14", ["sodium\nNa\n2.63\nbarium\nBa\n0.04\n"]], ["block_15", ["potassium\nK\n2.40\nnitrogen\nN\n0.03\n"]], ["block_16", ["magnesium\nMg\n1.93\nfluorine\nF\n0.03\n"]], ["block_17", ["hydrogen\nH\n0.87\nstrontium\nSr\n0.02\n"]], ["block_18", ["titanium\nTi\n0.58\nall others\n-\n0.47\n"]], ["block_19", ["Elemental Composition of Earth\n"]]], "page_32": [["block_0", [" Atoms and Molecules \n"]], ["block_1", ["An atom is the smallest particle of an element that has the properties of that element and can enter into a\nchemical combination. Consider the element gold, for example. Imagine cutting a gold nugget in half, then\ncutting one of the halves in half, and repeating this process until a piece of gold remained that was so small\nthat it could not be cut in half (regardless of how tiny your knife may be). This minimally sized piece of gold is\nan atom (from the Greek atomos, meaning \u201cindivisible\u201d) (Figure 1.12). This atom would no longer be gold if it\nwere divided any further.\n"]], ["block_2", [{"image_0": "32_0.png", "coords": [72, 159, 540, 355]}]], ["block_3", [" FIGURE 1.12 \n(a) This photograph shows a gold nugget. (b) A scanning-tunneling microscope (STM) can generate\n"]], ["block_4", ["views of the surfaces of solids, such as this image of a gold crystal. Each sphere represents one gold atom. (credit a:\nmodification of work by United States Geological Survey; credit b: modification of work by \u201cErwinrossen\u201d/Wikimedia\nCommons)\n"]], ["block_5", ["The first suggestion that matter is composed of atoms is attributed to the Greek philosophers Leucippus and\nDemocritus, who developed their ideas in the 5th century BCE. However, it was not until the early nineteenth\ncentury that John Dalton (1766\u20131844), a British schoolteacher with a keen interest in science, supported this\nhypothesis with quantitative measurements. Since that time, repeated experiments have confirmed many\naspects of this hypothesis, and it has become one of the central theories of chemistry. Other aspects of Dalton\u2019s\natomic theory are still used but with minor revisions (details of Dalton\u2019s theory are provided in the chapter on\natoms and molecules).\n"]], ["block_6", ["An atom is so small that its size is difficult to imagine. One of the smallest things we can see with our unaided\neye is a single thread of a spider web: These strands are about 1/10,000 of a centimeter (0.0001 cm) in\ndiameter. Although the cross-section of one strand is almost impossible to see without a microscope, it is huge\non an atomic scale. A single carbon atom in the web has a diameter of about 0.000000015 centimeter, and it\nwould take about 7000 carbon atoms to span the diameter of the strand. To put this in perspective, if a carbon\natom were the size of a dime, the cross-section of one strand would be larger than a football field, which would\nrequire about 150 million carbon atom \u201cdimes\u201d to cover it. (Figure 1.13) shows increasingly close microscopic\nand atomic-level views of ordinary cotton.\n"]], ["block_7", [" 1.2 \u2022 Phases and Classification of Matter \n 19 \n"]]], "page_33": [["block_0", [" 20 \n 1 \u2022 Essential Ideas \n"]], ["block_1", [{"image_0": "33_0.png", "coords": [72, 57, 540, 173]}]], ["block_2", [" FIGURE 1.13 \nThese images provide an increasingly closer view: (a) a cotton boll, (b) a single cotton fiber viewed\n"]], ["block_3", ["under an optical microscope (magnified 40 times), (c) an image of a cotton fiber obtained with an electron\nmicroscope (much higher magnification than with the optical microscope); and (d and e) atomic-level models of the\nfiber (spheres of different colors represent atoms of different elements). (credit c: modification of work by\n\u201cFeatheredtar\u201d/Wikimedia Commons)\n"]], ["block_4", ["An atom is so light that its mass is also difficult to imagine. A billion lead atoms (1,000,000,000 atoms) weigh\nabout 3\n10grams, a mass that is far too light to be weighed on even the world\u2019s most sensitive balances. It\n"]], ["block_5", ["would require over 300,000,000,000,000 lead atoms (300 trillion, or 3\n10) to be weighed, and they would\n"]], ["block_6", ["weigh only 0.0000001 gram.\n"]], ["block_7", ["It is rare to find collections of individual atoms. Only a few elements, such as the gases helium, neon, and\nargon, consist of a collection of individual atoms that move about independently of one another. Other\nelements, such as the gases hydrogen, nitrogen, oxygen, and chlorine, are composed of units that consist of\npairs of atoms (Figure 1.14). One form of the element phosphorus consists of units composed of four\nphosphorus atoms. The element sulfur exists in various forms, one of which consists of units composed of\neight sulfur atoms. These units are called molecules. A molecule consists of two or more atoms joined by\nstrong forces called chemical bonds. The atoms in a molecule move around as a unit, much like the cans of\nsoda in a six-pack or a bunch of keys joined together on a single key ring. A molecule may consist of two or\nmore identical atoms, as in the molecules found in the elements hydrogen, oxygen, and sulfur, or it may consist\nof two or more different atoms, as in the molecules found in water. Each water molecule is a unit that contains\ntwo hydrogen atoms and one oxygen atom. Each glucose molecule is a unit that contains 6 carbon atoms, 12\nhydrogen atoms, and 6 oxygen atoms. Like atoms, molecules are incredibly small and light. If an ordinary glass\nof water were enlarged to the size of the earth, the water molecules inside it would be about the size of golf\nballs.\n"]], ["block_8", [{"image_1": "33_1.png", "coords": [72, 485, 540, 619]}]], ["block_9", [" FIGURE 1.14 \nThe elements hydrogen, oxygen, phosphorus, and sulfur form molecules consisting of two or more\n"]], ["block_10", ["atoms of the same element. The compounds water, carbon dioxide, and glucose consist of combinations of atoms of\ndifferent elements.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["Chemistry in Everyday Life\n"]], ["block_13", [" Decomposition of Water / Production of Hydrogen \nWater consists of the elements hydrogen and oxygen combined in a 2 to 1 ratio. Water can be broken down\n"]]], "page_34": [["block_0", ["into hydrogen and oxygen gases by the addition of energy. One way to do this is with a battery or power\nsupply, as shown in (Figure 1.15).\n"]], ["block_1", [" FIGURE 1.15 \nThe decomposition of water is shown at the macroscopic, microscopic, and symbolic levels. The\n"]], ["block_2", ["battery provides an electric current (microscopic) that decomposes water. At the macroscopic level, the liquid\nseparates into the gases hydrogen (on the left) and oxygen (on the right). Symbolically, this change is presented\nby showing how liquid H2O separates into H2 and O2 gases.\n"]], ["block_3", ["The breakdown of water involves a rearrangement of the atoms in water molecules into different\nmolecules, each composed of two hydrogen atoms and two oxygen atoms, respectively. Two water\nmolecules form one oxygen molecule and two hydrogen molecules. The representation for what occurs,\n"]], ["block_4", ["The two gases produced have distinctly different properties. Oxygen is not flammable but is required for\ncombustion of a fuel, and hydrogen is highly flammable and a potent energy source. How might this\nknowledge be applied in our world? One application involves research into more fuel-efficient\ntransportation. Fuel-cell vehicles (FCV) run on hydrogen instead of gasoline (Figure 1.16). They are more\nefficient than vehicles with internal combustion engines, are nonpolluting, and reduce greenhouse gas\nemissions, making us less dependent on fossil fuels. FCVs are not yet economically viable, however, and\ncurrent hydrogen production depends on natural gas. If we can develop a process to economically\ndecompose water, or produce hydrogen in another environmentally sound way, FCVs may be the way of the\nfuture.\n"]], ["block_5", [{"image_0": "34_0.png", "coords": [90, 89, 522, 369]}]], ["block_6", ["will be explored in more depth in later chapters.\n"]], ["block_7", [" 1.2 \u2022 Phases and Classification of Matter \n 21 \n"]]], "page_35": [["block_0", [" 22 \n 1 \u2022 Essential Ideas \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" FIGURE 1.16 \nA fuel cell generates electrical energy from hydrogen and oxygen via an electrochemical process\n"]], ["block_3", ["and produces only water as the waste product.\n"]], ["block_4", ["Chemistry in Everyday Life\n"]], ["block_5", [" Chemistry of Cell Phones \nImagine how different your life would be without cell phones (Figure 1.17) and other smart devices. Cell\nphones are made from numerous chemical substances, which are extracted, refined, purified, and\nassembled using an extensive and in-depth understanding of chemical principles. About 30% of the\nelements that are found in nature are found within a typical smart phone. The case/body/frame consists of\na combination of sturdy, durable polymers composed primarily of carbon, hydrogen, oxygen, and nitrogen\n[acrylonitrile butadiene styrene (ABS) and polycarbonate thermoplastics], and light, strong, structural\nmetals, such as aluminum, magnesium, and iron. The display screen is made from a specially toughened\nglass (silica glass strengthened by the addition of aluminum, sodium, and potassium) and coated with a\nmaterial to make it conductive (such as indium tin oxide). The circuit board uses a semiconductor material\n(usually silicon); commonly used metals like copper, tin, silver, and gold; and more unfamiliar elements\nsuch as yttrium, praseodymium, and gadolinium. The battery relies upon lithium ions and a variety of\nother materials, including iron, cobalt, copper, polyethylene oxide, and polyacrylonitrile.\n"]], ["block_6", [{"image_0": "35_0.png", "coords": [130, 57, 481, 326]}]]], "page_36": [["block_0", [" 1.3 Physical and Chemical Properties \n"]], ["block_1", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_2", ["The characteristics that distinguish one substance from another are called properties. A physical property is a\ncharacteristic of matter that is not associated with a change in its chemical composition. Familiar examples of\nphysical properties include density, color, hardness, melting and boiling points, and electrical conductivity.\nSome physical properties, such as density and color, may be observed without changing the physical state of\nthe matter. Other physical properties, such as the melting temperature of iron or the freezing temperature of\nwater, can only be observed as matter undergoes a physical change. A physical change is a change in the state\nor properties of matter without any accompanying change in the chemical identities of the substances\ncontained in the matter. Physical changes are observed when wax melts, when sugar dissolves in coffee, and\nwhen steam condenses into liquid water (Figure 1.18). Other examples of physical changes include\nmagnetizing and demagnetizing metals (as is done with common antitheft security tags) and grinding solids\ninto powders (which can sometimes yield noticeable changes in color). In each of these examples, there is a\nchange in the physical state, form, or properties of the substance, but no change in its chemical composition.\n"]], ["block_3", ["\u2022\nIdentify properties of and changes in matter as physical or chemical\n"]], ["block_4", ["\u2022\nIdentify properties of matter as extensive or intensive\n"]], ["block_5", [" FIGURE 1.17 \nAlmost one-third of naturally occurring elements are used to make a cell phone. (credit:\n"]], ["block_6", ["modification of work by John Taylor)\n"]], ["block_7", [{"image_0": "36_0.png", "coords": [93, 57, 518, 283]}]], ["block_8", [" 1.3 \u2022 Physical and Chemical Properties \n 23 \n"]]], "page_37": [["block_0", [" 24 \n 1 \u2022 Essential Ideas \n"]], ["block_1", [" FIGURE 1.18 \n(a) Wax undergoes a physical change when solid wax is heated and forms liquid wax. (b) Steam\n"]], ["block_2", ["condensing inside a cooking pot is a physical change, as water vapor is changed into liquid water. (credit a:\nmodification of work by \u201c95jb14\u201d/Wikimedia Commons; credit b: modification of work by \u201cmjneuby\u201d/Flickr)\n"]], ["block_3", ["The change of one type of matter into another type (or the inability to change) is a chemical property .\nExamples of chemical properties include flammability, toxicity, acidity, and many other types of reactivity.\nIron, for example, combines with oxygen in the presence of water to form rust; chromium does not oxidize\n(Figure 1.19). Nitroglycerin is very dangerous because it explodes easily; neon poses almost no hazard because\nit is very unreactive.\n"]], ["block_4", [" FIGURE 1.19 \n(a) One of the chemical properties of iron is that it rusts; (b) one of the chemical properties of\n"]], ["block_5", ["chromium is that it does not. (credit a: modification of work by Tony Hisgett; credit b: modification of work by\n\u201cAtoma\u201d/Wikimedia Commons)\n"]], ["block_6", ["A chemical change always produces one or more types of matter that differ from the matter present before the\nchange. The formation of rust is a chemical change because rust is a different kind of matter than the iron,\noxygen, and water present before the rust formed. The explosion of nitroglycerin is a chemical change because\nthe gases produced are very different kinds of matter from the original substance. Other examples of chemical\nchanges include reactions that are performed in a lab (such as copper reacting with nitric acid), all forms of\ncombustion (burning), and food being cooked, digested, or rotting (Figure 1.20).\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [{"image_0": "37_0.png", "coords": [130, 57, 481, 203]}]], ["block_9", [{"image_1": "37_1.png", "coords": [130, 320, 481, 469]}]]], "page_38": [["block_0", [" FIGURE 1.20 \n(a) Copper and nitric acid undergo a chemical change to form copper nitrate and brown, gaseous\n"]], ["block_1", ["nitrogen dioxide. (b) During the combustion of a match, cellulose in the match and oxygen from the air undergo a\nchemical change to form carbon dioxide and water vapor. (c) Cooking red meat causes a number of chemical\nchanges, including the oxidation of iron in myoglobin that results in the familiar red-to-brown color change. (d) A\nbanana turning brown is a chemical change as new, darker (and less tasty) substances form. (credit b: modification\nof work by Jeff Turner; credit c: modification of work by Gloria Cabada-Leman; credit d: modification of work by\nRoberto Verzo)\n"]], ["block_2", ["Properties of matter fall into one of two categories. If the property depends on the amount of matter present, it\nis an extensive property . The mass and volume of a substance are examples of extensive properties; for\ninstance, a gallon of milk has a larger mass than a cup of milk. The value of an extensive property is directly\nproportional to the amount of matter in question. If the property of a sample of matter does not depend on the\namount of matter present, it is an intensive property . Temperature is an example of an intensive property. If\nthe gallon and cup of milk are each at 20 \u00b0C (room temperature), when they are combined, the temperature\nremains at 20 \u00b0C. As another example, consider the distinct but related properties of heat and temperature. A\ndrop of hot cooking oil spattered on your arm causes brief, minor discomfort, whereas a pot of hot oil yields\nsevere burns. Both the drop and the pot of oil are at the same temperature (an intensive property), but the pot\nclearly contains much more heat (extensive property).\n"]], ["block_3", ["Chemistry in Everyday Life\n"]], ["block_4", [" Hazard Diamond \nYou may have seen the symbol shown in Figure 1.21 on containers of chemicals in a laboratory or\nworkplace. Sometimes called a \u201cfire diamond\u201d or \u201chazard diamond,\u201d this chemical hazard diamond\nprovides valuable information that briefly summarizes the various dangers of which to be aware when\nworking with a particular substance.\n"]], ["block_5", [{"image_0": "38_0.png", "coords": [130, 57, 481, 366]}]], ["block_6", [" 1.3 \u2022 Physical and Chemical Properties \n 25 \n"]]], "page_39": [["block_0", [" 26 \n 1 \u2022 Essential Ideas \n"]], ["block_1", ["While many elements differ dramatically in their chemical and physical properties, some elements have\nsimilar properties. For example, many elements conduct heat and electricity well, whereas others are poor\nconductors. These properties can be used to sort the elements into three classes: metals (elements that\nconduct well), nonmetals (elements that conduct poorly), and metalloids (elements that have intermediate\nconductivities).\n"]], ["block_2", ["The periodic table is a table of elements that places elements with similar properties close together (Figure\n1.22). You will learn more about the periodic table as you continue your study of chemistry.\n"]], ["block_3", [" Access for free at openstax.org \n"]], ["block_4", [" FIGURE 1.21 \nThe National Fire Protection Agency (NFPA) hazard diamond summarizes the major hazards of a\n"]], ["block_5", ["chemical substance.\n"]], ["block_6", ["The National Fire Protection Agency (NFPA) 704 Hazard Identification System was developed by NFPA to\nprovide safety information about certain substances. The system details flammability, reactivity, health,\nand other hazards. Within the overall diamond symbol, the top (red) diamond specifies the level of fire\nhazard (temperature range for flash point). The blue (left) diamond indicates the level of health hazard. The\nyellow (right) diamond describes reactivity hazards, such as how readily the substance will undergo\ndetonation or a violent chemical change. The white (bottom) diamond points out special hazards, such as if\nit is an oxidizer (which allows the substance to burn in the absence of air/oxygen), undergoes an unusual or\ndangerous reaction with water, is corrosive, acidic, alkaline, a biological hazard, radioactive, and so on.\nEach hazard is rated on a scale from 0 to 4, with 0 being no hazard and 4 being extremely hazardous.\n"]], ["block_7", [{"image_0": "39_0.png", "coords": [90, 57, 522, 358]}]]], "page_40": [["block_0", [{"image_0": "40_0.png", "coords": [72, 57, 540, 423]}]], ["block_1", [" FIGURE 1.22 \nThe periodic table shows how elements may be grouped according to certain similar properties. Note\n"]], ["block_2", ["the background color denotes whether an element is a metal, metalloid, or nonmetal, whereas the element symbol\ncolor indicates whether it is a solid, liquid, or gas.\n"]], ["block_3", [" 1.4 Measurements \n"]], ["block_4", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_5", ["Measurements provide much of the information that informs the hypotheses, theories, and laws describing the\nbehavior of matter and energy in both the macroscopic and microscopic domains of chemistry. Every\nmeasurement provides three kinds of information: the size or magnitude of the measurement (a number); a\nstandard of comparison for the measurement (a unit); and an indication of the uncertainty of the\nmeasurement. While the number and unit are explicitly represented when a quantity is written, the\nuncertainty is an aspect of the measurement result that is more implicitly represented and will be discussed\nlater.\n"]], ["block_6", ["The number in the measurement can be represented in different ways, including decimal form and scientific\nnotation. (Scientific notation is also known as exponential notation; a review of this topic can be found in\nAppendix B.) For example, the maximum takeoff weight of a Boeing 777-200ER airliner is 298,000 kilograms,\nwhich can also be written as 2.98\n10kg. The mass of the average mosquito is about 0.0000025 kilograms,\n"]], ["block_7", ["\u2022\nExplain the process of measurement\n"]], ["block_8", ["\u2022\nIdentify the three basic parts of a quantity\n"]], ["block_9", ["\u2022\nDescribe the properties and units of length, mass, volume, density, temperature, and time\n"]], ["block_10", ["\u2022\nPerform basic unit calculations and conversions in the metric and other unit systems\n"]], ["block_11", [" 1.4 \u2022 Measurements \n 27 \n"]]], "page_41": [["block_0", [" 28 \n 1 \u2022 Essential Ideas \n"]], ["block_1", ["which can be written as 2.5\n10kg.\n"]], ["block_2", [" Units , such as liters, pounds, and centimeters, are standards of comparison for measurements. A 2-liter bottle\nof a soft drink contains a volume of beverage that is twice that of the accepted volume of 1 liter. The meat used\nto prepare a 0.25-pound hamburger weighs one-fourth as much as the accepted weight of 1 pound. Without\nunits, a number can be meaningless, confusing, or possibly life threatening. Suppose a doctor prescribes\nphenobarbital to control a patient\u2019s seizures and states a dosage of \u201c100\u201d without specifying units. Not only will\nthis be confusing to the medical professional giving the dose, but the consequences can be dire: 100 mg given\nthree times per day can be effective as an anticonvulsant, but a single dose of 100 g is more than 10 times the\nlethal amount.\n"]], ["block_3", ["The measurement units for seven fundamental properties (\u201cbase units\u201d) are listed in Table 1.2. The standards\nfor these units are fixed by international agreement, and they are called the International System of Units or\n SI Units (from the French, Le Syst\u00e8me International d\u2019Unit\u00e9s). SI units have been used by the United States\nNational Institute of Standards and Technology (NIST) since 1964. Units for other properties may be derived\nfrom these seven base units.\n"]], ["block_4", ["Everyday measurement units are often defined as fractions or multiples of other units. Milk is commonly\npackaged in containers of 1 gallon (4 quarts), 1 quart (0.25 gallon), and one pint (0.5 quart). This same\napproach is used with SI units, but these fractions or multiples are always powers of 10. Fractional or multiple\nSI units are named using a prefix and the name of the base unit. For example, a length of 1000 meters is also\ncalled a kilometer because the prefix kilo means \u201cone thousand,\u201d which in scientific notation is 10(1\nkilometer = 1000 m = 10m). The prefixes used and the powers to which 10 are raised are listed in Table 1.3.\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", [" TABLE 1.3 \n"]], ["block_7", [" Prefix \n Symbol \n Factor \n Example \n"]], ["block_8", ["femto\nf\n10\n1 femtosecond (fs) = 1\n10 s (0.000000000000001 s)\n"]], ["block_9", ["pico\np\n10\n1 picometer (pm) = 1\n10 m (0.000000000001 m)\n"]], ["block_10", [" TABLE 1.2 \n"]], ["block_11", [" Property Measured \n Name of Unit \n Symbol of Unit \n"]], ["block_12", ["length\nmeter\nm\n"]], ["block_13", ["mass\nkilogram\nkg\n"]], ["block_14", ["time\nsecond\ns\n"]], ["block_15", ["temperature\nkelvin\nK\n"]], ["block_16", ["electric current\nampere\nA\n"]], ["block_17", ["amount of substance\nmole\nmol\n"]], ["block_18", ["luminous intensity\ncandela\ncd\n"]], ["block_19", ["Base Units of the SI System\n"]], ["block_20", ["Common Unit Prefixes\n"]]], "page_42": [["block_0", ["Need a refresher or more practice with scientific notation? Visit this site (http://openstax.org/l/16notation) to\ngo over the basics of scientific notation.\n"]], ["block_1", [" SI Base Units \n"]], ["block_2", ["The initial units of the metric system, which eventually evolved into the SI system, were established in France\nduring the French Revolution. The original standards for the meter and the kilogram were adopted there in\n1799 and eventually by other countries. This section introduces four of the SI base units commonly used in\nchemistry. Other SI units will be introduced in subsequent chapters.\n"]], ["block_3", [" Length \nThe standard unit of length in both the SI and original metric systems is the meter (m) . A meter was originally\nspecified as 1/10,000,000 of the distance from the North Pole to the equator. It is now defined as the distance\nlight in a vacuum travels in 1/299,792,458 of a second. A meter is about 3 inches longer than a yard (Figure\n1.23); one meter is about 39.37 inches or 1.094 yards. Longer distances are often reported in kilometers (1 km\n= 1000 m = 10m), whereas shorter distances can be reported in centimeters (1 cm = 0.01 m = 10m) or\nmillimeters (1 mm = 0.001 m = 10m).\n"]], ["block_4", ["LINK TO LEARNING\n"]], ["block_5", [" TABLE 1.3 \n"]], ["block_6", [" Prefix \n Symbol \n Factor \n Example \n"]], ["block_7", ["nano\nn\n10\n4 nanograms (ng) = 4\n10 g (0.000000004 g)\n"]], ["block_8", ["micro\n\u00b5\n10\n1 microliter (\u03bcL) = 1\n10 L (0.000001 L)\n"]], ["block_9", ["milli\nm\n10\n2 millimoles (mmol) = 2\n10 mol (0.002 mol)\n"]], ["block_10", ["centi\nc\n10\n7 centimeters (cm) = 7\n10 m (0.07 m)\n"]], ["block_11", ["deci\nd\n10\n1 deciliter (dL) = 1\n10 L (0.1 L )\n"]], ["block_12", ["kilo\nk\n10\n1 kilometer (km) = 1\n10 m (1000 m)\n"]], ["block_13", ["mega\nM\n10\n3 megahertz (MHz) = 3\n10 Hz (3,000,000 Hz)\n"]], ["block_14", ["giga\nG\n10\n8 gigayears (Gyr) = 8\n10 yr (8,000,000,000 yr)\n"]], ["block_15", ["tera\nT\n10\n5 terawatts (TW) = 5\n10 W (5,000,000,000,000 W)\n"]], ["block_16", [" 1.4 \u2022 Measurements \n 29 \n"]]], "page_43": [["block_0", [" 30 \n 1 \u2022 Essential Ideas \n"]], ["block_1", [{"image_0": "43_0.png", "coords": [72, 57, 540, 287]}]], ["block_2", [" FIGURE 1.23 \nThe relative lengths of 1 m, 1 yd, 1 cm, and 1 in. are shown (not actual size), as well as comparisons\n"]], ["block_3", ["of 2.54 cm and 1 in., and of 1 m and 1.094 yd.\n"]], ["block_4", [" Mass \nThe standard unit of mass in the SI system is the kilogram (kg) . The kilogram was previously defined by the\nInternational Union of Pure and Applied Chemistry (IUPAC) as the mass of a specific reference object. This\nobject was originally one liter of pure water, and more recently it was a metal cylinder made from a platinum-\niridium alloy with a height and diameter of 39 mm (Figure 1.24). In May 2019, this definition was changed to\none that is based instead on precisely measured values of several fundamental physical constants.. One\nkilogram is about 2.2 pounds. The gram (g) is exactly equal to 1/1000 of the mass of the kilogram (10kg).\n"]], ["block_5", [" FIGURE 1.24 \nThis replica prototype kilogram as previously defined is housed at the National Institute of Standards\n"]], ["block_6", ["and Technology (NIST) in Maryland. (credit: National Institutes of Standards and Technology)\n"]], ["block_7", [" Temperature \n Temperature is an intensive property. The SI unit of temperature is the kelvin (K). The IUPAC convention is to\nuse kelvin (all lowercase) for the word, K (uppercase) for the unit symbol, and neither the word \u201cdegree\u201d nor\nthe degree symbol (\u00b0). The degree Celsius (\u00b0C) is also allowed in the SI system, with both the word \u201cdegree\u201d and\nthe degree symbol used for Celsius measurements. Celsius degrees are the same magnitude as those of kelvin,\nbut the two scales place their zeros in different places. Water freezes at 273.15 K (0 \u00b0C) and boils at 373.15 K\n(100 \u00b0C) by definition, and normal human body temperature is approximately 310 K (37 \u00b0C). The conversion\n"]], ["block_8", ["1 For details see https://www.nist.gov/pml/weights-and-measures/si-units-mass\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", [{"image_1": "43_1.png", "coords": [247, 417, 364, 583]}]]], "page_44": [["block_0", ["between these two units and the Fahrenheit scale will be discussed later in this chapter.\n"]], ["block_1", [" Time \nThe SI base unit of time is the second (s) . Small and large time intervals can be expressed with the appropriate\nprefixes; for example, 3 microseconds = 0.000003 s = 3\n10and 5 megaseconds = 5,000,000 s = 5\n10s.\n"]], ["block_2", ["Alternatively, hours, days, and years can be used.\n"]], ["block_3", [" Derived SI Units \n"]], ["block_4", ["We can derive many units from the seven SI base units. For example, we can use the base unit of length to\ndefine a unit of volume, and the base units of mass and length to define a unit of density.\n"]], ["block_5", [" Volume \n Volume is the measure of the amount of space occupied by an object. The standard SI unit of volume is defined\nby the base unit of length (Figure 1.25). The standard volume is a cubic meter (m 3 ) , a cube with an edge length\nof exactly one meter. To dispense a cubic meter of water, we could build a cubic box with edge lengths of\nexactly one meter. This box would hold a cubic meter of water or any other substance.\n"]], ["block_6", ["A more commonly used unit of volume is derived from the decimeter (0.1 m, or 10 cm). A cube with edge\nlengths of exactly one decimeter contains a volume of one cubic decimeter (dm). A liter (L) is the more\ncommon name for the cubic decimeter. One liter is about 1.06 quarts.\n"]], ["block_7", ["A cubic centimeter (cm 3 ) is the volume of a cube with an edge length of exactly one centimeter. The\nabbreviation cc (for c ubic c entimeter) is often used by health professionals. A cubic centimeter is equivalent to\na milliliter (mL) and is 1/1000 of a liter.\n"]], ["block_8", [" FIGURE 1.25 \n(a) The relative volumes are shown for cubes of 1 m, 1 dm(1 L), and 1 cm(1 mL) (not to scale). (b)\n"]], ["block_9", ["The diameter of a dime is compared relative to the edge length of a 1-cm(1-mL) cube.\n"]], ["block_10", [" Density \nWe use the mass and volume of a substance to determine its density. Thus, the units of density are defined by\nthe base units of mass and length.\n"]], ["block_11", ["The density of a substance is the ratio of the mass of a sample of the substance to its volume. The SI unit for\ndensity is the kilogram per cubic meter (kg/m). For many situations, however, this is an inconvenient unit,\nand we often use grams per cubic centimeter (g/cm) for the densities of solids and liquids, and grams per liter\n(g/L) for gases. Although there are exceptions, most liquids and solids have densities that range from about 0.7\ng/cm(the density of gasoline) to 19 g/cm(the density of gold). The density of air is about 1.2 g/L. Table 1.4\n"]], ["block_12", [{"image_0": "44_0.png", "coords": [90, 343, 522, 586]}]], ["block_13", [" 1.4 \u2022 Measurements \n 31 \n"]]], "page_45": [["block_0", [" 32 \n 1 \u2022 Essential Ideas \n"]], ["block_1", ["shows the densities of some common substances.\n"]], ["block_2", ["While there are many ways to determine the density of an object, perhaps the most straightforward method\ninvolves separately finding the mass and volume of the object, and then dividing the mass of the sample by its\nvolume. In the following example, the mass is found directly by weighing, but the volume is found indirectly\nthrough length measurements.\n"]], ["block_3", [" Calculation of Density \n"]], ["block_4", ["Gold\u2014in bricks, bars, and coins\u2014has been a form of currency for centuries. In order to swindle people into\npaying for a brick of gold without actually investing in a brick of gold, people have considered filling the\ncenters of hollow gold bricks with lead to fool buyers into thinking that the entire brick is gold. It does not\nwork: Lead is a dense substance, but its density is not as great as that of gold, 19.3 g/cm. What is the density of\nlead if a cube of lead has an edge length of 2.00 cm and a mass of 90.7 g?\n"]], ["block_5", [" Solution \n"]], ["block_6", ["The density of a substance can be calculated by dividing its mass by its volume. The volume of a cube is\ncalculated by cubing the edge length.\n"]], ["block_7", ["(We will discuss the reason for rounding to the first decimal place in the next section.)\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["(a) To three decimal places, what is the volume of a cube (cm) with an edge length of 0.843 cm?\n"]], ["block_10", ["(b) If the cube in part (a) is copper and has a mass of 5.34 g, what is the density of copper to two decimal\nplaces?\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["EXAMPLE 1.1\n"]], ["block_13", [" TABLE 1.4 \n"]], ["block_14", [" Solids \n Liquids \n Gases (at 25 \u00b0C and 1 atm) \n"]], ["block_15", ["ice (at 0 \u00b0C) 0.92 g/cm\nwater 1.0 g/cm\ndry air 1.20 g/L\n"]], ["block_16", ["oak (wood) 0.60\u20130.90 g/cm\nethanol 0.79 g/cm\noxygen 1.31 g/L\n"]], ["block_17", ["iron 7.9 g/cm\nacetone 0.79 g/cm\nnitrogen 1.14 g/L\n"]], ["block_18", ["copper 9.0 g/cm\nglycerin 1.26 g/cm\ncarbon dioxide 1.80 g/L\n"]], ["block_19", ["lead 11.3 g/cm\nolive oil 0.92 g/cm\nhelium 0.16 g/L\n"]], ["block_20", ["silver 10.5 g/cm\ngasoline 0.70\u20130.77 g/cm\nneon 0.83 g/L\n"]], ["block_21", ["gold 19.3 g/cm\nmercury 13.6 g/cm\nradon 9.1 g/L\n"]], ["block_22", ["Densities of Common Substances\n"]]], "page_46": [["block_0", [" Answer: \n(a) 0.599 cm; (b) 8.91 g/cm\n"]], ["block_1", ["To learn more about the relationship between mass, volume, and density, use this interactive simulator\n(http://openstax.org/l/16phetmasvolden) to explore the density of different materials.\n"]], ["block_2", [" Using Displacement of Water to Determine Density \n"]], ["block_3", ["This exercise uses a simulation (http://openstax.org/l/16phetmasvolden) to illustrate an alternative approach\nto the determination of density that involves measuring the object\u2019s volume via displacement of water. Use the\nsimulator to determine the densities iron and wood.\n"]], ["block_4", [" Solution \n"]], ["block_5", ["Click the \u201cturn fluid into water\u201d button in the simulator to adjust the density of liquid in the beaker to 1.00 g/\nmL. Remove the red block from the beaker and note the volume of water is 25.5 mL. Select the iron sample by\nclicking \u201ciron\u201d in the table of materials at the bottom of the screen, place the iron block on the balance pan,\nand observe its mass is 31.48 g. Transfer the iron block to the beaker and notice that it sinks, displacing a\nvolume of water equal to its own volume and causing the water level to rise to 29.5 mL. The volume of the iron\nblock is therefore:\n"]], ["block_6", ["The density of the iron is then calculated to be:\n"]], ["block_7", ["Remove the iron block from the beaker, change the block material to wood, and then repeat the mass and\nvolume measurements. Unlike iron, the wood block does not sink in the water but instead floats on the water\u2019s\nsurface. To measure its volume, drag it beneath the water\u2019s surface so that it is fully submerged.\n"]], ["block_8", ["Note: The sink versus float behavior illustrated in this example demonstrates the property of \u201cbuoyancy\u201d (see\nend of chapter Exercise 1.42 and Exercise 1.43).\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["Following the water displacement approach, use the simulator to measure the density of the foam sample.\n"]], ["block_11", [" Answer: \n0.230 g/mL\n"]], ["block_12", [" 1.5 Measurement Uncertainty, Accuracy, and Precision \n"]], ["block_13", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_14", ["Counting is the only type of measurement that is free from uncertainty, provided the number of objects being\n"]], ["block_15", ["\u2022\nDefine accuracy and precision\n"]], ["block_16", ["\u2022\nDistinguish exact and uncertain numbers\n"]], ["block_17", ["\u2022\nCorrectly represent uncertainty in quantities using significant figures\n"]], ["block_18", ["\u2022\nApply proper rounding rules to computed quantities\n"]], ["block_19", ["LINK TO LEARNING\n"]], ["block_20", ["EXAMPLE 1.2\n"]], ["block_21", [" 1.5 \u2022 Measurement Uncertainty, Accuracy, and Precision \n 33 \n"]]], "page_47": [["block_0", [" 34 \n 1 \u2022 Essential Ideas \n"]], ["block_1", ["This concept holds true for all measurements, even if you do not actively make an estimate. If you place a\nquarter on a standard electronic balance, you may obtain a reading of 6.72 g. The digits 6 and 7 are certain,\nand the 2 indicates that the mass of the quarter is likely between 6.71 and 6.73 grams. The quarter weighs\nabout 6.72 grams, with a nominal uncertainty in the measurement of \u00b1 0.01 gram. If the coin is weighed on a\nmore sensitive balance, the mass might be 6.723 g. This means its mass lies between 6.722 and 6.724 grams,\nan uncertainty of 0.001 gram. Every measurement has some uncertainty , which depends on the device used\n"]], ["block_2", ["counted does not change while the counting process is underway. The result of such a counting measurement\nis an example of an exact number . By counting the eggs in a carton, one can determine exactly how many eggs\nthe carton contains. The numbers of defined quantities are also exact. By definition, 1 foot is exactly 12 inches,\n1 inch is exactly 2.54 centimeters, and 1 gram is exactly 0.001 kilogram. Quantities derived from\nmeasurements other than counting, however, are uncertain to varying extents due to practical limitations of\nthe measurement process used.\n"]], ["block_3", [" Significant Figures in Measurement \n"]], ["block_4", ["The numbers of measured quantities, unlike defined or directly counted quantities, are not exact. To measure\nthe volume of liquid in a graduated cylinder, you should make a reading at the bottom of the meniscus, the\nlowest point on the curved surface of the liquid.\n"]], ["block_5", [{"image_0": "47_0.png", "coords": [72, 203, 540, 470]}]], ["block_6", [" FIGURE 1.26 \nTo measure the volume of liquid in this graduated cylinder, you must mentally subdivide the distance\n"]], ["block_7", ["between the 21 and 22 mL marks into tenths of a milliliter, and then make a reading (estimate) at the bottom of the\nmeniscus.\n"]], ["block_8", ["Refer to the illustration in Figure 1.26. The bottom of the meniscus in this case clearly lies between the 21 and\n22 markings, meaning the liquid volume is certainly greater than 21 mL but less than 22 mL. The meniscus\nappears to be a bit closer to the 22-mL mark than to the 21-mL mark, and so a reasonable estimate of the\nliquid\u2019s volume would be 21.6 mL. In the number 21.6, then, the digits 2 and 1 are certain, but the 6 is an\nestimate. Some people might estimate the meniscus position to be equally distant from each of the markings\nand estimate the tenth-place digit as 5, while others may think it to be even closer to the 22-mL mark and\nestimate this digit to be 7. Note that it would be pointless to attempt to estimate a digit for the hundredths\nplace, given that the tenths-place digit is uncertain. In general, numerical scales such as the one on this\ngraduated cylinder will permit measurements to one-tenth of the smallest scale division. The scale in this case\nhas 1-mL divisions, and so volumes may be measured to the nearest 0.1 mL.\n"]], ["block_9", [" Access for free at openstax.org \n"]]], "page_48": [["block_0", ["(and the user\u2019s ability). All of the digits in a measurement, including the uncertain last digit, are called\n significant figures or significant digits . Note that zero may be a measured value; for example, if you stand on\na scale that shows weight to the nearest pound and it shows \u201c120,\u201d then the 1 (hundreds), 2 (tens) and 0 (ones)\nare all significant (measured) values.\n"]], ["block_1", ["A measurement result is properly reported when its significant digits accurately represent the certainty of the\nmeasurement process. But what if you were analyzing a reported value and trying to determine what is\nsignificant and what is not? Well, for starters, all nonzero digits are significant, and it is only zeros that require\nsome thought. We will use the terms \u201cleading,\u201d \u201ctrailing,\u201d and \u201ccaptive\u201d for the zeros and will consider how to\ndeal with them.\n"]], ["block_2", [{"image_0": "48_0.png", "coords": [72, 183, 306, 263]}]], ["block_3", ["Starting with the first nonzero digit on the left, count this digit and all remaining digits to the right. This is the\nnumber of significant figures in the measurement unless the last digit is a trailing zero lying to the left of the\ndecimal point.\n"]], ["block_4", [{"image_1": "48_1.png", "coords": [72, 310, 540, 398]}]], ["block_5", ["Captive zeros result from measurement and are therefore always significant. Leading zeros, however, are\nnever significant\u2014they merely tell us where the decimal point is located.\n"]], ["block_6", [{"image_2": "48_2.png", "coords": [72, 432, 540, 504]}]], ["block_7", ["The leading zeros in this example are not significant. We could use exponential notation (as described in\nAppendix B) and express the number as 8.32407\n10; then the number 8.32407 contains all of the\n"]], ["block_8", ["significant figures, and 10locates the decimal point.\n"]], ["block_9", ["The number of significant figures is uncertain in a number that ends with a zero to the left of the decimal point\nlocation. The zeros in the measurement 1,300 grams could be significant or they could simply indicate where\nthe decimal point is located. The ambiguity can be resolved with the use of exponential notation: 1.3\n10(two\n"]], ["block_10", ["significant figures), 1.30\n10(three significant figures, if the tens place was measured), or 1.300\n10(four\n"]], ["block_11", ["significant figures, if the ones place was also measured). In cases where only the decimal-formatted number is\navailable, it is prudent to assume that all trailing zeros are not significant.\n"]], ["block_12", [{"image_3": "48_3.png", "coords": [72, 633, 423, 694]}]], ["block_13", ["When determining significant figures, be sure to pay attention to reported values and think about the\nmeasurement and significant figures in terms of what is reasonable or likely when evaluating whether the\n"]], ["block_14", [" 1.5 \u2022 Measurement Uncertainty, Accuracy, and Precision \n 35 \n"]]], "page_49": [["block_0", [" 36 \n 1 \u2022 Essential Ideas \n"]], ["block_1", ["value makes sense. For example, the official January 2014 census reported the resident population of the US\nas 317,297,725. Do you think the US population was correctly determined to the reported nine significant\nfigures, that is, to the exact number of people? People are constantly being born, dying, or moving into or out of\nthe country, and assumptions are made to account for the large number of people who are not actually\ncounted. Because of these uncertainties, it might be more reasonable to expect that we know the population to\nwithin perhaps a million or so, in which case the population should be reported as 3.17\n10people.\n"]], ["block_2", [" Significant Figures in Calculations \n"]], ["block_3", ["A second important principle of uncertainty is that results calculated from a measurement are at least as\nuncertain as the measurement itself. Take the uncertainty in measurements into account to avoid\nmisrepresenting the uncertainty in calculated results. One way to do this is to report the result of a calculation\nwith the correct number of significant figures, which is determined by the following three rules for rounding \nnumbers:\n"]], ["block_4", ["The following examples illustrate the application of this rule in rounding a few different numbers to three\nsignificant figures:\n"]], ["block_5", ["Let\u2019s work through these rules with a few examples.\n"]], ["block_6", [" Rounding Numbers \n"]], ["block_7", ["Round the following to the indicated number of significant figures:\n"]], ["block_8", ["(a) 31.57 (to two significant figures)\n"]], ["block_9", ["(b) 8.1649 (to three significant figures)\n"]], ["block_10", ["(c) 0.051065 (to four significant figures)\n"]], ["block_11", ["(d) 0.90275 (to four significant figures)\n"]], ["block_12", [" Solution \n"]], ["block_13", ["(a) 31.57 rounds \u201cup\u201d to 32 (the dropped digit is 5, and the retained digit is even)\n"]], ["block_14", ["(b) 8.1649 rounds \u201cdown\u201d to 8.16 (the dropped digit, 4, is less than 5)\n"]], ["block_15", ["(c) 0.051065 rounds \u201cdown\u201d to 0.05106 (the dropped digit is 5, and the retained digit is even)\n"]], ["block_16", ["(d) 0.90275 rounds \u201cup\u201d to 0.9028 (the dropped digit is 5, and the retained digit is even)\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["1.\nWhen adding or subtracting numbers, round the result to the same number of decimal places as the\nnumber with the least number of decimal places (the least certain value in terms of addition and\nsubtraction).\n"]], ["block_19", ["2.\nWhen multiplying or dividing numbers, round the result to the same number of digits as the number with\nthe least number of significant figures (the least certain value in terms of multiplication and division).\n"]], ["block_20", ["3.\nIf the digit to be dropped (the one immediately to the right of the digit to be retained) is less than 5, \u201cround\ndown\u201d and leave the retained digit unchanged; if it is more than 5, \u201cround up\u201d and increase the retained\ndigit by 1. If the dropped digit is 5, and it\u2019s either the last digit in the number or it\u2019s followed only by zeros,\nround up or down, whichever yields an even value for the retained digit. If any nonzero digits follow the\ndropped 5, round up. (The last part of this rule may strike you as a bit odd, but it\u2019s based on reliable\nstatistics and is aimed at avoiding any bias when dropping the digit \u201c5,\u201d since it is equally close to both\npossible values of the retained digit.)\n"]], ["block_21", ["\u2022\n0.028675 rounds \u201cup\u201d to 0.0287 (the dropped digit, 7, is greater than 5)\n"]], ["block_22", ["\u2022\n18.3384 rounds \u201cdown\u201d to 18.3 (the dropped digit, 3, is less than 5)\n"]], ["block_23", ["\u2022\n6.8752 rounds \u201cup\u201d to 6.88 (the dropped digit is 5, and a nonzero digit follows it)\n"]], ["block_24", ["\u2022\n92.85 rounds \u201cdown\u201d to 92.8 (the dropped digit is 5, and the retained digit is even)\n"]], ["block_25", ["EXAMPLE 1.3\n"]]], "page_50": [["block_0", [" Check Your Learning \n"]], ["block_1", ["Round the following to the indicated number of significant figures:\n"]], ["block_2", ["(a) 0.424 (to two significant figures)\n"]], ["block_3", ["(b) 0.0038661 (to three significant figures)\n"]], ["block_4", ["(c) 421.25 (to four significant figures)\n"]], ["block_5", ["(d) 28,683.5 (to five significant figures)\n"]], ["block_6", [" Answer: \n(a) 0.42; (b) 0.00387; (c) 421.2; (d) 28,684\n"]], ["block_7", [" Addition and Subtraction with Significant Figures \n"]], ["block_8", ["Rule: When adding or subtracting numbers, round the result to the same number of decimal places as the\nnumber with the fewest decimal places (i.e., the least certain value in terms of addition and subtraction).\n"]], ["block_9", ["(a) Add 1.0023 g and 4.383 g.\n"]], ["block_10", ["(b) Subtract 421.23 g from 486 g.\n"]], ["block_11", [" Solution \n"]], ["block_12", ["(a)\n"]], ["block_13", ["Answer is 5.385 g (round to the thousandths place; three decimal places)\n"]], ["block_14", ["(b)\n"]], ["block_15", ["Answer is 65 g (round to the ones place; no decimal places)\n"]], ["block_16", [{"image_0": "50_0.png", "coords": [72, 529, 455, 611]}]], ["block_17", [" Check Your Learning \n"]], ["block_18", ["(a) Add 2.334 mL and 0.31 mL.\n"]], ["block_19", ["(b) Subtract 55.8752 m from 56.533 m.\n"]], ["block_20", [" Answer: \n(a) 2.64 mL; (b) 0.658 m\n"]], ["block_21", ["EXAMPLE 1.4\n"]], ["block_22", [" 1.5 \u2022 Measurement Uncertainty, Accuracy, and Precision \n 37 \n"]]], "page_51": [["block_0", [" 38 \n 1 \u2022 Essential Ideas \n"]], ["block_1", [" Multiplication and Division with Significant Figures \n"]], ["block_2", ["Rule: When multiplying or dividing numbers, round the result to the same number of digits as the number\nwith the fewest significant figures (the least certain value in terms of multiplication and division).\n"]], ["block_3", ["(a) Multiply 0.6238 cm by 6.6 cm.\n"]], ["block_4", ["(b) Divide 421.23 g by 486 mL.\n"]], ["block_5", [" Solution \n"]], ["block_6", ["(a)\n"]], ["block_7", ["(b)\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["(a) Multiply 2.334 cm and 0.320 cm.\n"]], ["block_10", ["(b) Divide 55.8752 m by 56.53 s.\n"]], ["block_11", [" Answer: \n(a) 0.747 cm(b) 0.9884 m/s\n"]], ["block_12", ["In the midst of all these technicalities, it is important to keep in mind the reason for these rules about\nsignificant figures and rounding\u2014to correctly represent the certainty of the values reported and to ensure that\na calculated result is not represented as being more certain than the least certain value used in the calculation.\n"]], ["block_13", [" Calculation with Significant Figures \n"]], ["block_14", ["One common bathtub is 13.44 dm long, 5.920 dm wide, and 2.54 dm deep. Assume that the tub is rectangular\nand calculate its approximate volume in liters.\n"]], ["block_15", [" Solution \n"]], ["block_16", [" Check Your Learning \n"]], ["block_17", ["What is the density of a liquid with a mass of 31.1415 g and a volume of 30.13 cm?\n"]], ["block_18", [" Answer: \n1.034 g/mL\n"]], ["block_19", [" Access for free at openstax.org \n"]], ["block_20", ["EXAMPLE 1.5\n"]], ["block_21", ["EXAMPLE 1.6\n"]]], "page_52": [["block_0", [" Experimental Determination of Density Using Water Displacement \n"]], ["block_1", ["A piece of rebar is weighed and then submerged in a graduated cylinder partially filled with water, with results\nas shown.\n"]], ["block_2", [{"image_0": "52_0.png", "coords": [72, 137, 324, 329]}]], ["block_3", ["(a) Use these values to determine the density of this piece of rebar.\n"]], ["block_4", ["(b) Rebar is mostly iron. Does your result in (a) support this statement? How?\n"]], ["block_5", [" Solution \n"]], ["block_6", ["The volume of the piece of rebar is equal to the volume of the water displaced:\n"]], ["block_7", ["(rounded to the nearest 0.1 mL, per the rule for addition and subtraction)\n"]], ["block_8", ["The density is the mass-to-volume ratio:\n"]], ["block_9", ["(rounded to two significant figures, per the rule for multiplication and division)\n"]], ["block_10", ["From Table 1.4, the density of iron is 7.9 g/cm, very close to that of rebar, which lends some support to the fact\nthat rebar is mostly iron.\n"]], ["block_11", [" Check Your Learning \n"]], ["block_12", ["An irregularly shaped piece of a shiny yellowish material is weighed and then submerged in a graduated\ncylinder, with results as shown.\n"]], ["block_13", ["EXAMPLE 1.7\n"]], ["block_14", [" 1.5 \u2022 Measurement Uncertainty, Accuracy, and Precision \n 39 \n"]]], "page_53": [["block_0", [" 40 \n 1 \u2022 Essential Ideas \n"]], ["block_1", [{"image_0": "53_0.png", "coords": [72, 57, 324, 249]}]], ["block_2", ["(a) Use these values to determine the density of this material.\n"]], ["block_3", ["(b) Do you have any reasonable guesses as to the identity of this material? Explain your reasoning.\n"]], ["block_4", [" Answer: \n(a) 19 g/cm; (b) It is likely gold; the right appearance for gold and very close to the density given for gold in\nTable 1.4.\n"]], ["block_5", [" Accuracy and Precision \n"]], ["block_6", ["Scientists typically make repeated measurements of a quantity to ensure the quality of their findings and to\nevaluate both the precision and the accuracy of their results. Measurements are said to be precise if they yield\nvery similar results when repeated in the same manner. A measurement is considered accurate if it yields a\nresult that is very close to the true or accepted value. Precise values agree with each other; accurate values\nagree with a true value. These characterizations can be extended to other contexts, such as the results of an\narchery competition (Figure 1.27).\n"]], ["block_7", [" FIGURE 1.27 \n(a) These arrows are close to both the bull\u2019s eye and one another, so they are both accurate and\n"]], ["block_8", ["precise. (b) These arrows are close to one another but not on target, so they are precise but not accurate. (c) These\narrows are neither on target nor close to one another, so they are neither accurate nor precise.\n"]], ["block_9", ["Suppose a quality control chemist at a pharmaceutical company is tasked with checking the accuracy and\nprecision of three different machines that are meant to dispense 10 ounces (296 mL) of cough syrup into\nstorage bottles. She proceeds to use each machine to fill five bottles and then carefully determines the actual\nvolume dispensed, obtaining the results tabulated in Table 1.5.\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [{"image_1": "53_1.png", "coords": [102, 453, 509, 594]}]]], "page_54": [["block_0", ["Considering these results, she will report that dispenser #1 is precise (values all close to one another, within a\nfew tenths of a milliliter) but not accurate (none of the values are close to the target value of 296 mL, each\nbeing more than 10 mL too low). Results for dispenser #2 represent improved accuracy (each volume is less\nthan 3 mL away from 296 mL) but worse precision (volumes vary by more than 4 mL). Finally, she can report\nthat dispenser #3 is working well, dispensing cough syrup both accurately (all volumes within 0.1 mL of the\ntarget volume) and precisely (volumes differing from each other by no more than 0.2 mL).\n"]], ["block_1", [" 1.6 Mathematical Treatment of Measurement Results \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["It is often the case that a quantity of interest may not be easy (or even possible) to measure directly but instead\nmust be calculated from other directly measured properties and appropriate mathematical relationships. For\nexample, consider measuring the average speed of an athlete running sprints. This is typically accomplished\nby measuring the time required for the athlete to run from the starting line to the finish line, and the distance\nbetween these two lines, and then computing speed from the equation that relates these three properties:\n"]], ["block_4", ["An Olympic-quality sprinter can run 100 m in approximately 10 s, corresponding to an average speed of\n"]], ["block_5", ["Note that this simple arithmetic involves dividing the numbers of each measured quantity to yield the number\nof the computed quantity (100/10 = 10) and likewise dividing the units of each measured quantity to yield the\nunit of the computed quantity (m/s = m/s). Now, consider using this same relation to predict the time required\nfor a person running at this speed to travel a distance of 25 m. The same relation among the three properties is\nused, but in this case, the two quantities provided are a speed (10 m/s) and a distance (25 m). To yield the\nsought property, time, the equation must be rearranged appropriately:\n"]], ["block_6", ["The time can then be computed as:\n"]], ["block_7", ["\u2022\nExplain the dimensional analysis (factor label) approach to mathematical calculations involving quantities\n"]], ["block_8", ["\u2022\nUse dimensional analysis to carry out unit conversions for a given property and computations involving two or\nmore properties\n"]], ["block_9", [" TABLE 1.5 \n"]], ["block_10", ["Volume (mL) of Cough Medicine Delivered by 10-oz (296 mL) Dispensers\n"]], ["block_11", [" Dispenser #1 \n Dispenser #2 \n Dispenser #3 \n"]], ["block_12", ["283.3\n298.3\n296.1\n"]], ["block_13", ["284.1\n294.2\n295.9\n"]], ["block_14", ["283.9\n296.0\n296.1\n"]], ["block_15", ["284.0\n297.8\n296.0\n"]], ["block_16", ["284.1\n293.9\n296.1\n"]], ["block_17", [" 1.6 \u2022 Mathematical Treatment of Measurement Results \n 41 \n"]]], "page_55": [["block_0", [" 42 \n 1 \u2022 Essential Ideas \n"]], ["block_1", ["These calculations are examples of a versatile mathematical approach known as dimensional analysis (or the\n factor-label method ). Dimensional analysis is based on this premise: the units of quantities must be subjected\nto the same mathematical operations as their associated numbers. This method can be applied to\ncomputations ranging from simple unit conversions to more complex, multi-step calculations involving\nseveral different quantities.\n"]], ["block_2", ["Again, arithmetic on the numbers (25/10 = 2.5) was accompanied by the same arithmetic on the units (m/(m/s)\n= s) to yield the number and unit of the result, 2.5 s. Note that, just as for numbers, when a unit is divided by an\nidentical unit (in this case, m/m), the result is \u201c1\u201d\u2014or, as commonly phrased, the units \u201ccancel.\u201d\n"]], ["block_3", [" Conversion Factors and Dimensional Analysis \n"]], ["block_4", ["A ratio of two equivalent quantities expressed with different measurement units can be used as a unit \n conversion factor . For example, the lengths of 2.54 cm and 1 in. are equivalent (by definition), and so a unit\nconversion factor may be derived from the ratio,\n"]], ["block_5", ["Several other commonly used conversion factors are given in Table 1.6.\n"]], ["block_6", ["When a quantity (such as distance in inches) is multiplied by an appropriate unit conversion factor, the\nquantity is converted to an equivalent value with different units (such as distance in centimeters). For\nexample, a basketball player\u2019s vertical jump of 34 inches can be converted to centimeters by:\n"]], ["block_7", ["Since this simple arithmetic involves quantities, the premise of dimensional analysis requires that we multiply\nboth numbers and units. The numbers of these two quantities are multiplied to yield the number of the\nproduct quantity, 86, whereas the units are multiplied to yield\n. Just as for numbers, a ratio of identical\n"]], ["block_8", ["units is also numerically equal to one,\nand the unit product thus simplifies to cm. (When identical\n"]], ["block_9", ["units divide to yield a factor of 1, they are said to \u201ccancel.\u201d) Dimensional analysis may be used to confirm the\nproper application of unit conversion factors as demonstrated in the following example.\n"]], ["block_10", [" Using a Unit Conversion Factor \n"]], ["block_11", ["The mass of a competition frisbee is 125 g. Convert its mass to ounces using the unit conversion factor derived\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["EXAMPLE 1.8\n"]], ["block_14", [" TABLE 1.6 \n"]], ["block_15", [" Length \n Volume \n Mass \n"]], ["block_16", ["1 m = 1.0936 yd\n1 L = 1.0567 qt\n1 kg = 2.2046 lb\n"]], ["block_17", ["1 in. = 2.54 cm (exact)\n1 qt = 0.94635 L\n1 lb = 453.59 g\n"]], ["block_18", ["1 km = 0.62137 mi\n1 ft= 28.317 L\n1 (avoirdupois) oz = 28.349 g\n"]], ["block_19", ["1 mi = 1609.3 m\n1 tbsp = 14.787 mL\n1 (troy) oz = 31.103 g\n"]], ["block_20", ["Common Conversion Factors\n"]]], "page_56": [["block_0", ["from the relationship 1 oz = 28.349 g (Table 1.6).\n"]], ["block_1", [" Solution \n"]], ["block_2", ["Given the conversion factor, the mass in ounces may be derived using an equation similar to the one used for\nconverting length from inches to centimeters.\n"]], ["block_3", ["The unit conversion factor may be represented as:\n"]], ["block_4", ["The correct unit conversion factor is the ratio that cancels the units of grams and leaves ounces.\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["Convert a volume of 9.345 qt to liters.\n"]], ["block_7", [" Answer: \n8.844 L\n"]], ["block_8", ["Beyond simple unit conversions, the factor-label method can be used to solve more complex problems\ninvolving computations. Regardless of the details, the basic approach is the same\u2014all the factors involved in\nthe calculation must be appropriately oriented to ensure that their labels (units) will appropriately cancel and/\nor combine to yield the desired unit in the result. As your study of chemistry continues, you will encounter\nmany opportunities to apply this approach.\n"]], ["block_9", [" Computing Quantities from Measurement Results and Known Mathematical Relations \n"]], ["block_10", ["What is the density of common antifreeze in units of g/mL? A 4.00-qt sample of the antifreeze weighs 9.26 lb.\n"]], ["block_11", [" Solution \n"]], ["block_12", ["Since\n, we need to divide the mass in grams by the volume in milliliters. In general: the\n"]], ["block_13", ["number of units of B = the number of units of A\nunit conversion factor. The necessary conversion factors are\n"]], ["block_14", ["given in Table 1.6: 1 lb = 453.59 g; 1 L = 1.0567 qt; 1 L = 1,000 mL. Mass may be converted from pounds to\ngrams as follows:\n"]], ["block_15", ["Volume may be converted from quarts to milliliters via two steps:\n"]], ["block_16", ["Then,\n"]], ["block_17", ["Step 1. Convert quarts to liters.\n"]], ["block_18", ["Step 2. Convert liters to milliliters.\n"]], ["block_19", ["EXAMPLE 1.9\n"]], ["block_20", [" 1.6 \u2022 Mathematical Treatment of Measurement Results \n 43 \n"]]], "page_57": [["block_0", [" 44 \n 1 \u2022 Essential Ideas \n"]], ["block_1", ["Alternatively, the calculation could be set up in a way that uses three unit conversion factors sequentially as\nfollows:\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["What is the volume in liters of 1.000 oz, given that 1 L = 1.0567 qt and 1 qt = 32 oz (exactly)?\n"]], ["block_4", [" Answer: \n2.956 \u00d7 10L\n"]], ["block_5", [" Computing Quantities from Measurement Results and Known Mathematical Relations \n"]], ["block_6", ["While being driven from Philadelphia to Atlanta, a distance of about 1250 km, a 2014 Lamborghini Aventador\nRoadster uses 213 L gasoline.\n"]], ["block_7", ["(a) What (average) fuel economy, in miles per gallon, did the Roadster get during this trip?\n"]], ["block_8", ["(b) If gasoline costs $3.80 per gallon, what was the fuel cost for this trip?\n"]], ["block_9", [" Solution \n"]], ["block_10", ["(a) First convert distance from kilometers to miles:\n"]], ["block_11", ["and then convert volume from liters to gallons:\n"]], ["block_12", ["Finally,\n"]], ["block_13", ["Alternatively, the calculation could be set up in a way that uses all the conversion factors sequentially, as\nfollows:\n"]], ["block_14", ["(b) Using the previously calculated volume in gallons, we find:\n"]], ["block_15", [" Check Your Learning \n"]], ["block_16", ["A Toyota Prius Hybrid uses 59.7 L gasoline to drive from San Francisco to Seattle, a distance of 1300 km (two\nsignificant digits).\n"]], ["block_17", ["(a) What (average) fuel economy, in miles per gallon, did the Prius get during this trip?\n"]], ["block_18", ["(b) If gasoline costs $3.90 per gallon, what was the fuel cost for this trip?\n"]], ["block_19", [" Access for free at openstax.org \n"]], ["block_20", ["EXAMPLE 1.10\n"]]], "page_58": [["block_0", [" Answer: \n(a) 51 mpg; (b) $62\n"]], ["block_1", [" Conversion of Temperature Units \n"]], ["block_2", ["We use the word temperature to refer to the hotness or coldness of a substance. One way we measure a change\nin temperature is to use the fact that most substances expand when their temperature increases and contract\nwhen their temperature decreases. The liquid in a common glass thermometer changes its volume as the\ntemperature changes, and the position of the trapped liquid's surface along a printed scale may be used as a\nmeasure of temperature.\n"]], ["block_3", ["Temperature scales are defined relative to selected reference temperatures: Two of the most commonly used\nare the freezing and boiling temperatures of water at a specified atmospheric pressure. On the Celsius scale, 0\n\u00b0C is defined as the freezing temperature of water and 100 \u00b0C as the boiling temperature of water. The space\nbetween the two temperatures is divided into 100 equal intervals, which we call degrees. On the Fahrenheit \nscale, the freezing point of water is defined as 32 \u00b0F and the boiling temperature as 212 \u00b0F. The space between\nthese two points on a Fahrenheit thermometer is divided into 180 equal parts (degrees).\n"]], ["block_4", ["Defining the Celsius and Fahrenheit temperature scales as described in the previous paragraph results in a\nslightly more complex relationship between temperature values on these two scales than for different units of\nmeasure for other properties. Most measurement units for a given property are directly proportional to one\nanother (y = mx). Using familiar length units as one example:\n"]], ["block_5", ["where y = length in feet, x = length in inches, and the proportionality constant, m, is the conversion factor. The\nCelsius and Fahrenheit temperature scales, however, do not share a common zero point, and so the\nrelationship between these two scales is a linear one rather than a proportional one (y = mx + b). Consequently,\nconverting a temperature from one of these scales into the other requires more than simple multiplication by a\nconversion factor, m, it also must take into account differences in the scales\u2019 zero points (b).\n"]], ["block_6", ["The linear equation relating Celsius and Fahrenheit temperatures is easily derived from the two temperatures\nused to define each scale. Representing the Celsius temperature as x and the Fahrenheit temperature as y, the\nslope, m, is computed to be:\n"]], ["block_7", ["The y-intercept of the equation, b, is then calculated using either of the equivalent temperature pairs, (100 \u00b0C,\n212 \u00b0F) or (0 \u00b0C, 32 \u00b0F), as:\n"]], ["block_8", ["The equation relating the temperature (T) scales is then:\n"]], ["block_9", ["An abbreviated form of this equation that omits the measurement units is:\n"]], ["block_10", ["Rearrangement of this equation yields the form useful for converting from Fahrenheit to Celsius:\n"]], ["block_11", [" 1.6 \u2022 Mathematical Treatment of Measurement Results \n 45 \n"]]], "page_59": [["block_0", [" 46 \n 1 \u2022 Essential Ideas \n"]], ["block_1", ["As mentioned earlier in this chapter, the SI unit of temperature is the kelvin (K). Unlike the Celsius and\nFahrenheit scales, the kelvin scale is an absolute temperature scale in which 0 (zero) K corresponds to the\nlowest temperature that can theoretically be achieved. Since the kelvin temperature scale is absolute, a degree\nsymbol is not included in the unit abbreviation, K. The early 19th-century discovery of the relationship\nbetween a gas\u2019s volume and temperature suggested that the volume of a gas would be zero at \u2212273.15 \u00b0C. In\n1848, British physicist William Thompson, who later adopted the title of Lord Kelvin, proposed an absolute\ntemperature scale based on this concept (further treatment of this topic is provided in this text\u2019s chapter on\ngases).\n"]], ["block_2", ["The freezing temperature of water on this scale is 273.15 K and its boiling temperature is 373.15 K. Notice the\nnumerical difference in these two reference temperatures is 100, the same as for the Celsius scale, and so the\nlinear relation between these two temperature scales will exhibit a slope of\n. Following the same approach,\n"]], ["block_3", ["the equations for converting between the kelvin and Celsius temperature scales are derived to be:\n"]], ["block_4", ["The 273.15 in these equations has been determined experimentally, so it is not exact. Figure 1.28 shows the\nrelationship among the three temperature scales.\n"]], ["block_5", [{"image_0": "59_0.png", "coords": [72, 289, 540, 616]}]], ["block_6", ["Although the kelvin (absolute) temperature scale is the official SI temperature scale, Celsius is commonly used\nin many scientific contexts and is the scale of choice for nonscience contexts in almost all areas of the world.\nVery few countries (the U.S. and its territories, the Bahamas, Belize, Cayman Islands, and Palau) still use\nFahrenheit for weather, medicine, and cooking.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [" FIGURE 1.28 \nThe Fahrenheit, Celsius, and kelvin temperature scales are compared.\n"]]], "page_60": [["block_0", [" Conversion from Celsius \n"]], ["block_1", ["Normal body temperature has been commonly accepted as 37.0 \u00b0C (although it varies depending on time of\nday and method of measurement, as well as among individuals). What is this temperature on the kelvin scale\nand on the Fahrenheit scale?\n"]], ["block_2", [" Solution \n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["Convert 80.92 \u00b0C to K and \u00b0F.\n"]], ["block_5", [" Answer: \n354.07 K, 177.7 \u00b0F\n"]], ["block_6", [" Conversion from Fahrenheit \n"]], ["block_7", ["Baking a ready-made pizza calls for an oven temperature of 450 \u00b0F. If you are in Europe, and your oven\nthermometer uses the Celsius scale, what is the setting? What is the kelvin temperature?\n"]], ["block_8", [" Solution \n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["Convert 50 \u00b0F to \u00b0C and K.\n"]], ["block_11", [" Answer: \n10 \u00b0C, 280 K\n"]], ["block_12", ["EXAMPLE 1.11\n"]], ["block_13", ["EXAMPLE 1.12\n"]], ["block_14", [" 1.6 \u2022 Mathematical Treatment of Measurement Results \n 47 \n"]]], "page_61": [["block_0", [" 48 \n 1 \u2022 Key Terms \n"]], ["block_1", [" Key Terms \n"]], ["block_2", [" accuracy \nhow closely a measurement aligns with a\n"]], ["block_3", [" atom \nsmallest particle of an element that can enter\n"]], ["block_4", [" Celsius (\u00b0C) \nunit of temperature; water freezes at 0\n"]], ["block_5", [" chemical change \nchange producing a different\n"]], ["block_6", [" chemical property \nbehavior that is related to the\n"]], ["block_7", [" chemistry \nstudy of the composition, properties,\n"]], ["block_8", [" compound \npure substance that can be\n"]], ["block_9", [" cubic centimeter (cm 3 or cc) \nvolume of a cube\n"]], ["block_10", [" cubic meter (m 3 ) \nSI unit of volume\n"]], ["block_11", [" density \nratio of mass to volume for a substance or\n"]], ["block_12", [" dimensional analysis \n(also, factor-label method)\n"]], ["block_13", [" element \nsubstance that is composed of a single\n"]], ["block_14", [" exact number \nnumber derived by counting or by\n"]], ["block_15", [" extensive property \nproperty of a substance that\n"]], ["block_16", [" Fahrenheit \nunit of temperature; water freezes at\n"]], ["block_17", [" gas \nstate in which matter has neither definite\n"]], ["block_18", [" heterogeneous mixture \ncombination of\n"]], ["block_19", [" homogeneous mixture \n(also, solution)\n"]], ["block_20", [" hypothesis \ntentative explanation of observations\n"]], ["block_21", [" intensive property \nproperty of a substance that is\n"]], ["block_22", [" kelvin (K) \nSI unit of temperature; 273.15 K = 0 \u00baC\n"]], ["block_23", [" kilogram (kg) \nstandard SI unit of mass; 1 kg =\n"]], ["block_24", [" law \nstatement that summarizes a vast number of\n"]], ["block_25", [" Access for free at openstax.org \n"]], ["block_26", ["correct value\n"]], ["block_27", ["into a chemical combination\n"]], ["block_28", ["\u00b0C and boils at 100 \u00b0C on this scale\n"]], ["block_29", ["kind of matter from the original kind of matter\n"]], ["block_30", ["change of one kind of matter into another kind of\n matter \n"]], ["block_31", ["and interactions of matter\n"]], ["block_32", ["decomposed into two or more elements\n"]], ["block_33", ["with an edge length of exactly 1 cm\n"]], ["block_34", ["object\n"]], ["block_35", ["versatile mathematical approach that can be\napplied to computations ranging from simple unit\nconversions to more complex, multi-step\ncalculations involving several different quantities\n"]], ["block_36", ["type of atom; a substance that cannot be\ndecomposed by a chemical change\n"]], ["block_37", ["definition\n"]], ["block_38", ["depends on the amount of the substance\n"]], ["block_39", ["32 \u00b0F and boils at 212 \u00b0F on this scale\n"]], ["block_40", ["volume nor shape\n"]], ["block_41", ["substances with a composition that varies from\npoint to point\n"]], ["block_42", ["combination of substances with a composition\nthat is uniform throughout\n"]], ["block_43", ["that acts as a guide for gathering and checking\ninformation\n"]], ["block_44", ["independent of the amount of the substance\n"]], ["block_45", ["approximately 2.2 pounds\n"]], ["block_46", ["experimental observations, and describes or\n"]], ["block_47", [" law of conservation of matter \nwhen matter\n"]], ["block_48", [" length \nmeasure of one dimension of an object\n"]], ["block_49", [" liquid \nstate of matter that has a definite volume but\n"]], ["block_50", [" liter (L) \n(also, cubic decimeter) unit of volume; 1 L\n"]], ["block_51", [" macroscopic domain \nrealm of everyday things\n"]], ["block_52", [" mass \nfundamental property indicating amount of\n"]], ["block_53", [" matter \nanything that occupies space and has mass\n"]], ["block_54", [" meter (m) \nstandard metric and SI unit of length; 1\n"]], ["block_55", [" microscopic domain \nrealm of things that are\n"]], ["block_56", [" milliliter (mL) \n1/1,000 of a liter; equal to 1 cm\n"]], ["block_57", [" mixture \nmatter that can be separated into its\n"]], ["block_58", [" molecule \nbonded collection of two or more atoms\n"]], ["block_59", [" physical change \nchange in the state or properties\n"]], ["block_60", [" physical property \ncharacteristic of matter that is\n"]], ["block_61", [" plasma \ngaseous state of matter containing a large\n"]], ["block_62", [" precision \nhow closely a measurement matches the\n"]], ["block_63", [" pure substance \nhomogeneous substance that has\n"]], ["block_64", [" rounding \nprocedure used to ensure that calculated\n"]], ["block_65", [" scientific method \npath of discovery that leads\n"]], ["block_66", [" second (s) \nSI unit of time\n"]], ["block_67", [" SI units (International System of Units) \n"]], ["block_68", [" significant figures \n(also, significant digits) all of\n"]], ["block_69", ["standards fixed by international agreement in the\nInternational System of Units (Le Syst\u00e8me\nInternational d\u2019Unit\u00e9s)\n"]], ["block_70", ["predicts some aspect of the natural world\n"]], ["block_71", ["converts from one type to another or changes\nform, there is no detectable change in the total\namount of matter present\n"]], ["block_72", ["indefinite shape\n"]], ["block_73", ["= 1,000 cm\n"]], ["block_74", ["that are large enough to sense directly by human\nsight and touch\n"]], ["block_75", [" matter \n"]], ["block_76", ["m = approximately 1.094 yards\n"]], ["block_77", ["much too small to be sensed directly\n"]], ["block_78", ["components by physical means\n"]], ["block_79", ["of the same or different elements\n"]], ["block_80", ["of matter that does not involve a change in its\nchemical composition\n"]], ["block_81", ["not associated with any change in its chemical\ncomposition\n"]], ["block_82", ["number of electrically charged atoms and/or\nmolecules\n"]], ["block_83", ["same measurement when repeated\n"]], ["block_84", ["a constant composition\n"]], ["block_85", ["results properly reflect the uncertainty in the\nmeasurements used in the calculation\n"]], ["block_86", ["from question and observation to law or\nhypothesis to theory, combined with\nexperimental verification of the hypothesis and\nany necessary modification of the theory\n"]]], "page_62": [["block_0", [" solid \nstate of matter that is rigid, has a definite\n"]], ["block_1", [" symbolic domain \nspecialized language used to\n"]], ["block_2", [" temperature \nintensive property representing the\n"]], ["block_3", [" Key Equations \n"]], ["block_4", [" Summary \n"]], ["block_5", [" 1.1 Chemistry in Context \n"]], ["block_6", ["Chemistry deals with the composition, structure,\nand properties of matter, and the ways by which\nvarious forms of matter may be interconverted.\nThus, it occupies a central place in the study and\npractice of science and technology. Chemists use the\nscientific method to perform experiments, pose\nhypotheses, and formulate laws and develop\ntheories, so that they can better understand the\nbehavior of the natural world. To do so, they operate\nin the macroscopic, microscopic, and symbolic\ndomains. Chemists measure, analyze, purify, and\nsynthesize a wide variety of substances that are\nimportant to our lives.\n"]], ["block_7", [" 1.2 Phases and Classification of Matter \n"]], ["block_8", ["Matter is anything that occupies space and has\nmass. The basic building block of matter is the atom,\nthe smallest unit of an element that can enter into\ncombinations with atoms of the same or other\nelements. In many substances, atoms are combined\ninto molecules. On earth, matter commonly exists in\nthree states: solids, of fixed shape and volume;\nliquids, of variable shape but fixed volume; and\ngases, of variable shape and volume. Under high-\ntemperature conditions, matter also can exist as a\nplasma. Most matter is a mixture: It is composed of\ntwo or more types of matter that can be present in\nvarying amounts and can be separated by physical\nmeans. Heterogeneous mixtures vary in\n"]], ["block_9", ["the measured digits in a determination, including\nthe uncertain last digit\n"]], ["block_10", ["shape, and has a fairly constant volume\n"]], ["block_11", ["represent components of the macroscopic and\nmicroscopic domains, such as chemical symbols,\nchemical formulas, chemical equations, graphs,\ndrawings, and calculations\n"]], ["block_12", ["hotness or coldness of matter\n"]], ["block_13", [" theory \nwell-substantiated, comprehensive,\n"]], ["block_14", [" uncertainty \nestimate of amount by which\n"]], ["block_15", [" unit \nstandard of comparison for measurements\n"]], ["block_16", [" unit conversion factor \nratio of equivalent\n"]], ["block_17", [" volume \namount of space occupied by an object\n"]], ["block_18", [" weight \nforce that gravity exerts on an object\n"]], ["block_19", ["composition from point to point; homogeneous\nmixtures have the same composition from point to\npoint. Pure substances consist of only one type of\nmatter. A pure substance can be an element, which\nconsists of only one type of atom and cannot be\nbroken down by a chemical change, or a compound,\nwhich consists of two or more types of atoms.\n"]], ["block_20", [" 1.3 Physical and Chemical Properties \n"]], ["block_21", ["All substances have distinct physical and chemical\nproperties, and may undergo physical or chemical\nchanges. Physical properties, such as hardness and\nboiling point, and physical changes, such as melting\nor freezing, do not involve a change in the\ncomposition of matter. Chemical properties, such\nflammability and acidity, and chemical changes,\nsuch as rusting, involve production of matter that\ndiffers from that present beforehand.\n"]], ["block_22", ["Measurable properties fall into one of two categories.\nExtensive properties depend on the amount of\nmatter present, for example, the mass of gold.\nIntensive properties do not depend on the amount of\nmatter present, for example, the density of gold.\nHeat is an example of an extensive property, and\ntemperature is an example of an intensive property.\n"]], ["block_23", [" 1.4 Measurements \n"]], ["block_24", ["Measurements provide quantitative information that\nis critical in studying and practicing chemistry. Each\nmeasurement has an amount, a unit for comparison,\n"]], ["block_25", ["testable explanation of a particular aspect of\nnature\n"]], ["block_26", ["measurement differs from true value\n"]], ["block_27", ["quantities expressed with different units; used to\nconvert from one unit to a different unit\n"]], ["block_28", [" 1 \u2022 Key Equations \n 49 \n"]]], "page_63": [["block_0", [" 50 \n 1 \u2022 Exercises \n"]], ["block_1", ["and an uncertainty. Measurements can be\nrepresented in either decimal or scientific notation.\nScientists primarily use SI (International System)\nunits such as meters, seconds, and kilograms, as\nwell as derived units, such as liters (for volume) and\ng/cm(for density). In many cases, it is convenient to\nuse prefixes that yield fractional and multiple units,\nsuch as microseconds (10seconds) and megahertz\n(10hertz), respectively.\n"]], ["block_2", [" 1.5 Measurement Uncertainty, Accuracy, \n and Precision \n"]], ["block_3", ["Quantities can be defined or measured. Measured\nquantities have an associated uncertainty that is\nrepresented by the number of significant figures in\nthe quantity\u2019s number. The uncertainty of a\ncalculated quantity depends on the uncertainties in\nthe quantities used in the calculation and is\n"]], ["block_4", [" Exercises \n"]], ["block_5", [" 1.1 Chemistry in Context \n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [" 1 . Explain how you could experimentally determine whether the outside temperature is higher or lower than\n"]], ["block_8", [" 2 . Identify each of the following statements as being most similar to a hypothesis, a law, or a theory. Explain\n"]], ["block_9", [" 3 . Identify each of the following statements as being most similar to a hypothesis, a law, or a theory. Explain\n"]], ["block_10", [" 4 . Identify each of the underlined items as a part of either the macroscopic domain, the microscopic domain,\n"]], ["block_11", [" 5 . Identify each of the underlined items as a part of either the macroscopic domain, the microscopic domain,\n"]], ["block_12", [" 6 . According to one theory, the pressure of a gas increases as its volume decreases because the molecules in\n"]], ["block_13", ["0 \u00b0C (32 \u00b0F) without using a thermometer.\n"]], ["block_14", ["your reasoning.\n(a) Falling barometric pressure precedes the onset of bad weather.\n(b) All life on earth has evolved from a common, primitive organism through the process of natural\nselection.\n(c) My truck\u2019s gas mileage has dropped significantly, probably because it\u2019s due for a tune-up.\n"]], ["block_15", ["your reasoning.\n(a) The pressure of a sample of gas is directly proportional to the temperature of the gas.\n(b) Matter consists of tiny particles that can combine in specific ratios to form substances with specific\nproperties.\n(c) At a higher temperature, solids (such as salt or sugar) will dissolve better in water.\n"]], ["block_16", ["or the symbolic domain of chemistry. For any in the symbolic domain, indicate whether they are symbols\nfor a macroscopic or a microscopic feature.\n(a) The mass of a lead pipe is 14 lb.\n(b) The mass of a certain chlorine atom is 35 amu.\n(c) A bottle with a label that reads Al contains aluminum metal.\n(d) Al is the symbol for an aluminum atom.\n"]], ["block_17", ["or the symbolic domain of chemistry. For those in the symbolic domain, indicate whether they are symbols\nfor a macroscopic or a microscopic feature.\n(a) A certain molecule contains one H atom and one Cl atom.\n(b) Copper wire has a density of about 8 g/cm.\n(c) The bottle contains 15 grams of Ni powder.\n(d) A sulfur molecule is composed of eight sulfur atoms.\n"]], ["block_18", ["the gas have to move a shorter distance to hit the walls of the container. Does this theory follow a\nmacroscopic or microscopic description of chemical behavior? Explain your answer.\n"]], ["block_19", ["reflected in how the value is rounded. Quantities are\ncharacterized with regard to accuracy (closeness to a\ntrue or accepted value) and precision (variation\namong replicate measurement results).\n"]], ["block_20", [" 1.6 Mathematical Treatment of \n Measurement Results \n"]], ["block_21", ["Measurements are made using a variety of units. It is\noften useful or necessary to convert a measured\nquantity from one unit into another. These\nconversions are accomplished using unit conversion\nfactors, which are derived by simple applications of\na mathematical approach called the factor-label\nmethod or dimensional analysis. This strategy is\nalso employed to calculate sought quantities using\nmeasured quantities and appropriate mathematical\nrelations.\n"]]], "page_64": [["block_0", [" 1.2 Phases and Classification of Matter \n"]], ["block_1", [" 8 . Why is an object\u2019s mass, rather than its weight, used to indicate the amount of matter it contains?\n 9 . What properties distinguish solids from liquids? Liquids from gases? Solids from gases?\n 10 . How does a heterogeneous mixture differ from a homogeneous mixture? How are they similar?\n 11 . How does a homogeneous mixture differ from a pure substance? How are they similar?\n 12 . How does an element differ from a compound? How are they similar?\n 13 . How do molecules of elements and molecules of compounds differ? In what ways are they similar?\n 14 . How does an atom differ from a molecule? In what ways are they similar?\n 15 . Many of the items you purchase are mixtures of pure compounds. Select three of these commercial\n"]], ["block_2", [" 16 . Classify each of the following as an element, a compound, or a mixture:\n"]], ["block_3", [" 17 . Classify each of the following as an element, a compound, or a mixture:\n"]], ["block_4", [" 18 . A sulfur atom and a sulfur molecule are not identical. What is the difference?\n 19 . How are the molecules in oxygen gas, the molecules in hydrogen gas, and water molecules similar? How\n"]], ["block_5", [" 20 . Why are astronauts in space said to be \u201cweightless,\u201d but not \u201cmassless\u201d?\n 21 . Prepare a list of the principal chemicals consumed and produced during the operation of an automobile.\n 22 . Matter is everywhere around us. Make a list by name of fifteen different kinds of matter that you encounter\n"]], ["block_6", [" 23 . When elemental iron corrodes it combines with oxygen in the air to ultimately form red brown iron(III)\n"]], ["block_7", [" 7 . The amount of heat required to melt 2 lbs of ice is twice the amount of heat required to melt 1 lb of ice. Is\n"]], ["block_8", ["this observation a macroscopic or microscopic description of chemical behavior? Explain your answer.\n"]], ["block_9", ["products and prepare a list of the ingredients that are pure compounds.\n"]], ["block_10", ["(a) copper\n(b) water\n(c) nitrogen\n(d) sulfur\n(e) air\n(f) sucrose\n(g) a substance composed of molecules each of which contains two iodine atoms\n(h) gasoline\n"]], ["block_11", ["(a) iron\n(b) oxygen\n(c) mercury oxide\n(d) pancake syrup\n(e) carbon dioxide\n(f) a substance composed of molecules each of which contains one hydrogen atom and one chlorine atom\n(g) baking soda\n(h) baking powder\n"]], ["block_12", ["do they differ?\n"]], ["block_13", ["every day. Your list should include (and label at least one example of each) the following: a solid, a liquid, a\ngas, an element, a compound, a homogenous mixture, a heterogeneous mixture, and a pure substance.\n"]], ["block_14", ["oxide called rust. (a) If a shiny iron nail with an initial mass of 23.2 g is weighed after being coated in a\nlayer of rust, would you expect the mass to have increased, decreased, or remained the same? Explain. (b)\nIf the mass of the iron nail increases to 24.1 g, what mass of oxygen combined with the iron?\n"]], ["block_15", [" 1 \u2022 Exercises \n 51 \n"]]], "page_65": [["block_0", [" 52 \n 1 \u2022 Exercises \n"]], ["block_1", [" 24 . As stated in the text, convincing examples that demonstrate the law of conservation of matter outside of\n"]], ["block_2", [" 25 . Yeast converts glucose to ethanol and carbon dioxide during anaerobic fermentation as depicted in the\n"]], ["block_3", [" 1.3 Physical and Chemical Properties \n"]], ["block_4", [" 26 . Classify the six underlined properties in the following paragraph as chemical or physical:\n"]], ["block_5", [" 27 . Classify each of the following changes as physical or chemical:\n"]], ["block_6", [" 28 . Classify each of the following changes as physical or chemical:\n"]], ["block_7", [" 29 . The volume of a sample of oxygen gas changed from 10 mL to 11 mL as the temperature changed. Is this a\n"]], ["block_8", [" 30 . A 2.0-liter volume of hydrogen gas combined with 1.0 liter of oxygen gas to produce 2.0 liters of water\n"]], ["block_9", [" 31 . Explain the difference between extensive properties and intensive properties.\n 32 . Identify the following properties as either extensive or intensive.\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["the laboratory are few and far between. Indicate whether the mass would increase, decrease, or stay the\nsame for the following scenarios where chemical reactions take place:\n(a) Exactly one pound of bread dough is placed in a baking tin. The dough is cooked in an oven at 350 \u00b0F\nreleasing a wonderful aroma of freshly baked bread during the cooking process. Is the mass of the baked\nloaf less than, greater than, or the same as the one pound of original dough? Explain.\n(b) When magnesium burns in air a white flaky ash of magnesium oxide is produced. Is the mass of\nmagnesium oxide less than, greater than, or the same as the original piece of magnesium? Explain.\n(c) Antoine Lavoisier, the French scientist credited with first stating the law of conservation of matter,\nheated a mixture of tin and air in a sealed flask to produce tin oxide. Did the mass of the sealed flask and\ncontents decrease, increase, or remain the same after the heating?\n"]], ["block_12", ["simple chemical equation here:\n"]], ["block_13", ["(a) If 200.0 g of glucose is fully converted, what will be the total mass of ethanol and carbon dioxide\nproduced?\n(b) If the fermentation is carried out in an open container, would you expect the mass of the container and\ncontents after fermentation to be less than, greater than, or the same as the mass of the container and\ncontents before fermentation? Explain.\n(c) If 97.7 g of carbon dioxide is produced, what mass of ethanol is produced?\n"]], ["block_14", ["Fluorine is a pale yellow gas that reacts with most substances. The free element melts at \u2212220 \u00b0C and boils\nat \u2212188 \u00b0C. Finely divided metals burn in fluorine with a bright flame. Nineteen grams of fluorine will\nreact with 1.0 gram of hydrogen.\n"]], ["block_15", ["(a) condensation of steam\n(b) burning of gasoline\n(c) souring of milk\n(d) dissolving of sugar in water\n(e) melting of gold\n"]], ["block_16", ["(a) coal burning\n(b) ice melting\n(c) mixing chocolate syrup with milk\n(d) explosion of a firecracker\n(e) magnetizing of a screwdriver\n"]], ["block_17", ["chemical or physical change?\n"]], ["block_18", ["vapor. Does oxygen undergo a chemical or physical change?\n"]], ["block_19", ["(a) volume\n(b) temperature\n(c) humidity\n(d) heat\n(e) boiling point\n"]]], "page_66": [["block_0", [" 33 . The density (d) of a substance is an intensive property that is defined as the ratio of its mass (m) to its\n"]], ["block_1", [" 1.4 Measurements \n"]], ["block_2", [" 34 . Is one liter about an ounce, a pint, a quart, or a gallon?\n 35 . Is a meter about an inch, a foot, a yard, or a mile?\n 36 . Indicate the SI base units or derived units that are appropriate for the following measurements:\n"]], ["block_3", [" 37 . Indicate the SI base units or derived units that are appropriate for the following measurements:\n"]], ["block_4", [" 38 . Give the name and symbol of the prefixes used with SI units to indicate multiplication by the following\n"]], ["block_5", [" 39 . Give the name of the prefix and the quantity indicated by the following symbols that are used with SI base\n"]], ["block_6", [" 40 . A large piece of jewelry has a mass of 132.6 g. A graduated cylinder initially contains 48.6 mL water. When\n"]], ["block_7", ["volume (V).\n"]], ["block_8", ["Considering that mass and volume are both extensive properties, explain why their ratio, density, is\nintensive.\n"]], ["block_9", ["(a) the length of a marathon race (26 miles 385 yards)\n(b) the mass of an automobile\n(c) the volume of a swimming pool\n(d) the speed of an airplane\n(e) the density of gold\n(f) the area of a football field\n(g) the maximum temperature at the South Pole on April 1, 1913\n"]], ["block_10", ["(a) the mass of the moon\n(b) the distance from Dallas to Oklahoma City\n(c) the speed of sound\n(d) the density of air\n(e) the temperature at which alcohol boils\n(f) the area of the state of Delaware\n(g) the volume of a flu shot or a measles vaccination\n"]], ["block_11", ["exact quantities.\n(a) 10\n"]], ["block_12", ["(b) 10\n"]], ["block_13", ["(c) 0.1\n(d) 10\n"]], ["block_14", ["(e) 1,000,000\n(f) 0.000001\n"]], ["block_15", ["units.\n(a) c\n(b) d\n(c) G\n(d) k\n(e) m\n(f) n\n(g) p\n(h) T\n"]], ["block_16", ["the jewelry is submerged in the graduated cylinder, the total volume increases to 61.2 mL.\n(a) Determine the density of this piece of jewelry.\n(b) Assuming that the jewelry is made from only one substance, what substance is it likely to be? Explain.\n"]], ["block_17", [" 1 \u2022 Exercises \n 53 \n"]]], "page_67": [["block_0", [" 54 \n 1 \u2022 Exercises \n"]], ["block_1", [" 41 . Visit this density simulation (http://openstax.org/l/16phetmasvolden) and click the \"turn fluid into water\"\n"]], ["block_2", [" 42 . Visit this density simulation (http://openstax.org/l/16phetmasvolden) and click the \"reset\" button to\n"]], ["block_3", [" 43 . Visit this density simulation (http://openstax.org/l/16phetmasvolden) and click the \u201cturn fluid into water\u201d\n"]], ["block_4", [" 1.5 Measurement Uncertainty, Accuracy, and Precision \n"]], ["block_5", [" 44 . Express each of the following numbers in scientific notation with correct significant figures:\n"]], ["block_6", [" 45 . Express each of the following numbers in exponential notation with correct significant figures:\n"]], ["block_7", [" 46 . Indicate whether each of the following can be determined exactly or must be measured with some degree\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["button to adjust the density of liquid in the beaker to 1.00 g/mL.\n(a) Use the water displacement approach to measure the mass and volume of the unknown material\n(select the green block with question marks).\n(b) Use the measured mass and volume data from step (a) to calculate the density of the unknown\nmaterial.\n(c) Link out to the link provided.\n(d) Assuming this material is a copper-containing gemstone, identify its three most likely identities by\ncomparing the measured density to the values tabulated at this gemstone density guide\n(https://www.ajsgem.com/articles/gemstone-density-definitive-guide.html).\n(e) How are mass and density related for blocks of the same volume?\n"]], ["block_10", ["ensure all simulator parameters are at their default values.\n(a) Use the water displacement approach to measure the mass and volume of the red block.\n(b) Use the measured mass and volume data from step (a) to calculate the density of the red block.\n(c) Use the vertical green slide control to adjust the fluid density to values well above, then well below, and\nfinally nearly equal to the density of the red block, reporting your observations.\n"]], ["block_11", ["button to adjust the density of liquid in the beaker to 1.00 g/mL. Change the block material to foam, and\nthen wait patiently until the foam block stops bobbing up and down in the water.\n(a) The foam block should be floating on the surface of the water (that is, only partially submerged). What\nis the volume of water displaced?\n(b) Use the water volume from part (a) and the density of water (1.00 g/mL) to calculate the mass of water\ndisplaced.\n(c) Remove and weigh the foam block. How does the block\u2019s mass compare to the mass of displaced water\nfrom part (b)?\n"]], ["block_12", ["(a) 711.0\n(b) 0.239\n(c) 90743\n(d) 134.2\n(e) 0.05499\n(f) 10000.0\n(g) 0.000000738592\n"]], ["block_13", ["(a) 704\n(b) 0.03344\n(c) 547.9\n(d) 22086\n(e) 1000.00\n(f) 0.0000000651\n(g) 0.007157\n"]], ["block_14", ["of uncertainty:\n(a) the number of eggs in a basket\n(b) the mass of a dozen eggs\n(c) the number of gallons of gasoline necessary to fill an automobile gas tank\n(d) the number of cm in 2 m\n(e) the mass of a textbook\n(f) the time required to drive from San Francisco to Kansas City at an average speed of 53 mi/h\n"]]], "page_68": [["block_0", [" 47 . Indicate whether each of the following can be determined exactly or must be measured with some degree\n"]], ["block_1", [" 48 . How many significant figures are contained in each of the following measurements?\n"]], ["block_2", [" 49 . How many significant figures are contained in each of the following measurements?\n"]], ["block_3", [" 50 . The following quantities were reported on the labels of commercial products. Determine the number of\n"]], ["block_4", [" 51 . Round off each of the following numbers to two significant figures:\n"]], ["block_5", [" 52 . Round off each of the following numbers to two significant figures:\n"]], ["block_6", ["of uncertainty:\n(a) the number of seconds in an hour\n(b) the number of pages in this book\n(c) the number of grams in your weight\n(d) the number of grams in 3 kilograms\n(e) the volume of water you drink in one day\n(f) the distance from San Francisco to Kansas City\n"]], ["block_7", ["(a) 38.7 g\n(b) 2\n10m\n"]], ["block_8", ["(c) 3,486,002 kg\n(d) 9.74150\n10J\n"]], ["block_9", ["(e) 0.0613 cm\n"]], ["block_10", ["(f) 17.0 kg\n(g) 0.01400 g/mL\n"]], ["block_11", ["(a) 53 cm\n(b) 2.05\n10m\n"]], ["block_12", ["(c) 86,002 J\n(d) 9.740\n10m/s\n"]], ["block_13", ["(e) 10.0613 m\n"]], ["block_14", ["(f) 0.17 g/mL\n(g) 0.88400 s\n"]], ["block_15", ["significant figures in each.\n(a) 0.0055 g active ingredients\n(b) 12 tablets\n(c) 3% hydrogen peroxide\n(d) 5.5 ounces\n(e) 473 mL\n(f) 1.75% bismuth\n(g) 0.001% phosphoric acid\n(h) 99.80% inert ingredients\n"]], ["block_16", ["(a) 0.436\n(b) 9.000\n(c) 27.2\n(d) 135\n(e) 1.497\n10\n"]], ["block_17", ["(f) 0.445\n"]], ["block_18", ["(a) 517\n(b) 86.3\n(c) 6.382\n10\n"]], ["block_19", ["(d) 5.0008\n(e) 22.497\n(f) 0.885\n"]], ["block_20", [" 1 \u2022 Exercises \n 55 \n"]]], "page_69": [["block_0", [" 56 \n 1 \u2022 Exercises \n"]], ["block_1", [" 53 . Perform the following calculations and report each answer with the correct number of significant figures.\n"]], ["block_2", [" 54 . Perform the following calculations and report each answer with the correct number of significant figures.\n"]], ["block_3", [" 55 . Consider the results of the archery contest shown in this figure.\n"]], ["block_4", [" 56 . Classify the following sets of measurements as accurate, precise, both, or neither.\n"]], ["block_5", [" 1.6 Mathematical Treatment of Measurement Results \n"]], ["block_6", [" 57 . Write conversion factors (as ratios) for the number of:\n"]], ["block_7", [" 58 . Write conversion factors (as ratios) for the number of:\n"]], ["block_8", [" 59 . The label on a soft drink bottle gives the volume in two units: 2.0 L and 67.6 fl oz. Use this information to\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["(a) 628\n342\n"]], ["block_11", ["(b) (5.63\n10)\n(7.4\n10)\n"]], ["block_12", ["(c)\n"]], ["block_13", ["(d) 8119\n0.000023\n"]], ["block_14", ["(e) 14.98 + 27,340 + 84.7593\n(f) 42.7 + 0.259\n"]], ["block_15", ["(a) 62.8\n34\n"]], ["block_16", ["(b) 0.147 + 0.0066 + 0.012\n(c) 38\n95\n1.792\n"]], ["block_17", ["(d) 15 \u2013 0.15 \u2013 0.6155\n(e)\n"]], ["block_18", ["(f) 140 + 7.68 + 0.014\n(g) 28.7 \u2013 0.0483\n"]], ["block_19", ["(h)\n"]], ["block_20", ["(a) Which archer is most precise?\n(b) Which archer is most accurate?\n(c) Who is both least precise and least accurate?\n"]], ["block_21", [{"image_0": "69_0.png", "coords": [91, 319, 523, 486]}]], ["block_22", ["(a) Checking for consistency in the weight of chocolate chip cookies: 17.27 g, 13.05 g, 19.46 g, 16.92 g\n(b) Testing the volume of a batch of 25-mL pipettes: 27.02 mL, 26.99 mL, 26.97 mL, 27.01 mL\n(c) Determining the purity of gold: 99.9999%, 99.9998%, 99.9998%, 99.9999%\n"]], ["block_23", ["(a) yards in 1 meter\n(b) liters in 1 liquid quart\n(c) pounds in 1 kilogram\n"]], ["block_24", ["(a) kilometers in 1 mile\n(b) liters in 1 cubic foot\n(c) grams in 1 ounce\n"]], ["block_25", ["derive a conversion factor between the English and metric units. How many significant figures can you\njustify in your conversion factor?\n"]]], "page_70": [["block_0", [" 60 . The label on a box of cereal gives the mass of cereal in two units: 978 grams and 34.5 oz. Use this\n"]], ["block_1", [" 61 . Soccer is played with a round ball having a circumference between 27 and 28 in. and a weight between 14\n"]], ["block_2", [" 62 . A woman\u2019s basketball has a circumference between 28.5 and 29.0 inches and a maximum weight of 20\n"]], ["block_3", [" 63 . How many milliliters of a soft drink are contained in a 12.0-oz can?\n 64 . A barrel of oil is exactly 42 gal. How many liters of oil are in a barrel?\n 65 . The diameter of a red blood cell is about 3\n10in. What is its diameter in centimeters?\n"]], ["block_4", [" 66 . The distance between the centers of the two oxygen atoms in an oxygen molecule is 1.21\n10cm. What\n"]], ["block_5", [" 67 . Is a 197-lb weight lifter light enough to compete in a class limited to those weighing 90 kg or less?\n 68 . A very good 197-lb weight lifter lifted 192 kg in a move called the clean and jerk. What was the mass of the\n"]], ["block_6", [" 69 . Many medical laboratory tests are run using 5.0 \u03bcL blood serum. What is this volume in milliliters?\n 70 . If an aspirin tablet contains 325 mg aspirin, how many grams of aspirin does it contain?\n 71 . Use scientific (exponential) notation to express the following quantities in terms of the SI base units in\n"]], ["block_7", [" 72 . Complete the following conversions between SI units.\n"]], ["block_8", [" 73 . Gasoline is sold by the liter in many countries. How many liters are required to fill a 12.0-gal gas tank?\n 74 . Milk is sold by the liter in many countries. What is the volume of exactly 1/2 gal of milk in liters?\n 75 . A long ton is defined as exactly 2240 lb. What is this mass in kilograms?\n 76 . Make the conversion indicated in each of the following:\n"]], ["block_9", ["information to find a conversion factor between the English and metric units. How many significant\nfigures can you justify in your conversion factor?\n"]], ["block_10", ["and 16 oz. What are these specifications in units of centimeters and grams?\n"]], ["block_11", ["ounces (two significant figures). What are these specifications in units of centimeters and grams?\n"]], ["block_12", ["is this distance in inches?\n"]], ["block_13", ["weight lifted in pounds?\n"]], ["block_14", ["Table 1.2:\n(a) 0.13 g\n(b) 232 Gg\n(c) 5.23 pm\n(d) 86.3 mg\n(e) 37.6 cm\n(f) 54 \u03bcm\n(g) 1 Ts\n(h) 27 ps\n(i) 0.15 mK\n"]], ["block_15", ["(a) 612 g = ________ mg\n(b) 8.160 m = ________ cm\n(c) 3779 \u03bcg = ________ g\n(d) 781 mL = ________ L\n(e) 4.18 kg = ________ g\n(f) 27.8 m = ________ km\n(g) 0.13 mL = ________ L\n(h) 1738 km = ________ m\n(i) 1.9 Gg = ________ g\n"]], ["block_16", ["(a) the men\u2019s world record long jump, 29 ft 4\u00bc in., to meters\n(b) the greatest depth of the ocean, about 6.5 mi, to kilometers\n(c) the area of the state of Oregon, 96,981 mi, to square kilometers\n(d) the volume of 1 gill (exactly 4 oz) to milliliters\n(e) the estimated volume of the oceans, 330,000,000 mi, to cubic kilometers.\n(f) the mass of a 3525-lb car to kilograms\n(g) the mass of a 2.3-oz egg to grams\n"]], ["block_17", [" 1 \u2022 Exercises \n 57 \n"]]], "page_71": [["block_0", [" 58 \n 1 \u2022 Exercises \n"]], ["block_1", [" 77 . Make the conversion indicated in each of the following:\n"]], ["block_2", [" 78 . Many chemistry conferences have held a 50-Trillion Angstrom Run (two significant figures). How long is\n"]], ["block_3", [" 79 . A chemist\u2019s 50-Trillion Angstrom Run (see Exercise 1.78) would be an archeologist\u2019s 10,900 cubit run.\n"]], ["block_4", [" 80 . The gas tank of a certain luxury automobile holds 22.3 gallons according to the owner\u2019s manual. If the\n"]], ["block_5", [" 81 . As an instructor is preparing for an experiment, he requires 225 g phosphoric acid. The only container\n"]], ["block_6", [" 82 . To prepare for a laboratory period, a student lab assistant needs 125 g of a compound. A bottle containing\n"]], ["block_7", [" 83 . A chemistry student is 159 cm tall and weighs 45.8 kg. What is her height in inches and weight in pounds?\n 84 . In a recent Grand Prix, the winner completed the race with an average speed of 229.8 km/h. What was his\n"]], ["block_8", [" 85 . Solve these problems about lumber dimensions.\n"]], ["block_9", [" 86 . The mercury content of a stream was believed to be above the minimum considered safe\u20141 part per\n"]], ["block_10", [" 87 . Calculate the density of aluminum if 27.6 cmhas a mass of 74.6 g.\n 88 . Osmium is one of the densest elements known. What is its density if 2.72 g has a volume of 0.121 cm?\n 89 . Calculate these masses.\n"]], ["block_11", [" 90 . Calculate these masses.\n"]], ["block_12", [" 91 . Calculate these volumes.\n"]], ["block_13", [" 92 . Calculate these volumes.\n"]], ["block_14", [" 93 . Convert the boiling temperature of gold, 2966 \u00b0C, into degrees Fahrenheit and kelvin.\n 94 . Convert the temperature of scalding water, 54 \u00b0C, into degrees Fahrenheit and kelvin.\n 95 . Convert the temperature of the coldest area in a freezer, \u221210 \u00b0F, to degrees Celsius and kelvin.\n 96 . Convert the temperature of dry ice, \u221277 \u00b0C, into degrees Fahrenheit and kelvin.\n 97 . Convert the boiling temperature of liquid ammonia, \u221228.1 \u00b0F, into degrees Celsius and kelvin.\n 98 . The label on a pressurized can of spray disinfectant warns against heating the can above 130 \u00b0F. What are\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["(a) the length of a soccer field, 120 m (three significant figures), to feet\n(b) the height of Mt. Kilimanjaro, at 19,565 ft, the highest mountain in Africa, to kilometers\n(c) the area of an 8.5- \u00d7 11-inch sheet of paper in cm\n"]], ["block_17", ["(d) the displacement volume of an automobile engine, 161 in., to liters\n(e) the estimated mass of the atmosphere, 5.6 \u00d7 10tons, to kilograms\n(f) the mass of a bushel of rye, 32.0 lb, to kilograms\n(g) the mass of a 5.00-grain aspirin tablet to milligrams (1 grain = 0.00229 oz)\n"]], ["block_18", ["this run in kilometers and in miles? (1 \u00c5 = 1\n10m)\n"]], ["block_19", ["How long is one cubit in meters and in feet? (1 \u00c5 = 1\n10cm)\n"]], ["block_20", ["density of gasoline is 0.8206 g/mL, determine the mass in kilograms and pounds of the fuel in a full tank.\n"]], ["block_21", ["readily available is a 150-mL Erlenmeyer flask. Is it large enough to contain the acid, whose density is 1.83\ng/mL?\n"]], ["block_22", ["1/4 lb is available. Did the student have enough of the compound?\n"]], ["block_23", ["speed in miles per hour, meters per second, and feet per second?\n"]], ["block_24", ["(a) To describe to a European how houses are constructed in the US, the dimensions of \u201ctwo-by-four\u201d\nlumber must be converted into metric units. The thickness\nwidth\nlength dimensions are 1.50 in.\n"]], ["block_25", ["3.50 in.\n8.00 ft in the US. What are the dimensions in cm\ncm\nm?\n"]], ["block_26", ["(b) This lumber can be used as vertical studs, which are typically placed 16.0 in. apart. What is that\ndistance in centimeters?\n"]], ["block_27", ["billion (ppb) by weight. An analysis indicated that the concentration was 0.68 parts per billion. What\nquantity of mercury in grams was present in 15.0 L of the water, the density of which is 0.998 g/ml?\n"]], ["block_28", ["(a) What is the mass of 6.00 cmof mercury, density = 13.5939 g/cm?\n(b) What is the mass of 25.0 mL octane, density = 0.702 g/cm?\n"]], ["block_29", ["(a) What is the mass of 4.00 cmof sodium, density = 0.97 g/cm?\n(b) What is the mass of 125 mL gaseous chlorine, density = 3.16 g/L?\n"]], ["block_30", ["(a) What is the volume of 25 g iodine, density = 4.93 g/cm?\n(b) What is the volume of 3.28 g gaseous hydrogen, density = 0.089 g/L?\n"]], ["block_31", ["(a) What is the volume of 11.3 g graphite, density = 2.25 g/cm?\n(b) What is the volume of 39.657 g bromine, density = 2.928 g/cm?\n"]], ["block_32", ["the corresponding temperatures on the Celsius and kelvin temperature scales?\n"]]], "page_72": [["block_0", [" 99 . The weather in Europe was unusually warm during the summer of 1995. The TV news reported\n"]], ["block_1", ["temperatures as high as 45 \u00b0C. What was the temperature on the Fahrenheit scale?\n"]], ["block_2", [" 1 \u2022 Exercises \n 59 \n"]]], "page_73": [["block_0", [" 60 \n 1 \u2022 Exercises \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_74": [["block_0", ["CHAPTER 2\nAtoms, Molecules, and Ions\n"]], ["block_1", [{"image_0": "74_0.png", "coords": [72, 104, 622, 349]}]], ["block_2", [" Figure 2.1 \nAnalysis of molecules in an exhaled breath can provide valuable information, leading to early diagnosis\n"]], ["block_3", ["of diseases or detection of environmental exposure to harmful substances. (credit: modification of work by Paul\nFlowers)\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 2.1 Early Ideas in Atomic Theory \n 2.2 Evolution of Atomic Theory \n 2.3 Atomic Structure and Symbolism \n 2.4 Chemical Formulas \n 2.5 The Periodic Table \n"]], ["block_6", [" 2.6 Ionic and Molecular Compounds \n 2.7 Chemical Nomenclature \n"]], ["block_7", [" INTRODUCTION \n"]], ["block_8", ["to delayed detection and diagnosis. Most noninvasive screening procedures aren't reliable, and patients often\nresist more accurate methods due to discomfort with the procedures or with the potential danger that the\nprocedures cause. But what if you could be accurately diagnosed through a simple breath test?\n"]], ["block_9", ["Early detection of biomarkers, substances that indicate an organism\u2019s disease or physiological state, could\nallow diagnosis and treatment before a condition becomes serious or irreversible. Recent studies have shown\nthat your exhaled breath can contain molecules that may be biomarkers for recent exposure to environmental\ncontaminants or for pathological conditions ranging from asthma to lung cancer. Scientists are working to\ndevelop biomarker \u201cfingerprints\u201d that could be used to diagnose a specific disease based on the amounts and\nidentities of certain molecules in a patient\u2019s exhaled breath. In Sangeeta Bhatia's lab at MIT, a team used\nsubstances that react specifically inside diseased lung tissue; the products of the reactions will be present as\nbiomarkers that can be identified through mass spectrometry (an analytical method discussed later in the\nchapter). A potential application would allow patients with early symptoms to inhale or ingest a \"sensor\"\n"]], ["block_10", ["Lung diseases and lung cancers are among the world's most devastating illnesses partly due\n"]]], "page_75": [["block_0", [" 62 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", ["substance, and, minutes later, to breathe into a detector for diagnosis. Similar research by scientists such as\nLaura L\u00f3pez-S\u00e1nchez has provided similar processes for lung cancer. An essential concept underlying this goal\nis that of a molecule\u2019s identity, which is determined by the numbers and types of atoms it contains, and how\nthey are bonded together. This chapter will describe some of the fundamental chemical principles related to\nthe composition of matter, including those central to the concept of molecular identity.\n"]], ["block_2", [" 2.1 Early Ideas in Atomic Theory \n"]], ["block_3", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_4", ["The earliest recorded discussion of the basic structure of matter comes from ancient Greek philosophers, the\nscientists of their day. In the fifth century BC, Leucippus and Democritus argued that all matter was composed\nof small, finite particles that they called atomos, a term derived from the Greek word for \u201cindivisible.\u201d They\nthought of atoms as moving particles that differed in shape and size, and which could join together. Later,\nAristotle and others came to the conclusion that matter consisted of various combinations of the four\n\u201celements\u201d\u2014fire, earth, air, and water\u2014and could be infinitely divided. Interestingly, these philosophers\nthought about atoms and \u201celements\u201d as philosophical concepts, but apparently never considered performing\nexperiments to test their ideas.\n"]], ["block_5", ["The Aristotelian view of the composition of matter held sway for over two thousand years, until English\nschoolteacher John Dalton helped to revolutionize chemistry with his hypothesis that the behavior of matter\ncould be explained using an atomic theory . First published in 1807, many of Dalton\u2019s hypotheses about the\nmicroscopic features of matter are still valid in modern atomic theory . Here are the postulates of Dalton\u2019s \n atomic theory .\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", ["1.\nMatter is composed of exceedingly small particles called atoms. An atom is the smallest unit of an element\nthat can participate in a chemical change.\n"]], ["block_8", ["2.\nAn element consists of only one type of atom, which has a mass that is characteristic of the element and is\nthe same for all atoms of that element (Figure 2.2). A macroscopic sample of an element contains an\nincredibly large number of atoms, all of which have identical chemical properties.\n"]], ["block_9", ["3.\nAtoms of one element differ in properties from atoms of all other elements.\n"]], ["block_10", ["4.\nA compound consists of atoms of two or more elements combined in a small, whole-number ratio. In a\ngiven compound, the numbers of atoms of each of its elements are always present in the same ratio\n(Figure 2.3).\n"]], ["block_11", ["\u2022\nState the postulates of Dalton\u2019s atomic theory\n"]], ["block_12", ["\u2022\nUse postulates of Dalton\u2019s atomic theory to explain the laws of definite and multiple proportions\n"]], ["block_13", [" FIGURE 2.2 \nA pre-1982 copper penny (left) contains approximately 3\n10copper atoms (several dozen are\n"]], ["block_14", ["represented as brown spheres at the right), each of which has the same chemical properties. (credit:\nmodification of work by \u201cslgckgc\u201d/Flickr)\n"]], ["block_15", [{"image_0": "75_0.png", "coords": [198, 446, 432, 541]}]]], "page_76": [["block_0", ["Dalton\u2019s atomic theory provides a microscopic explanation of the many macroscopic properties of matter that\nyou\u2019ve learned about. For example, if an element such as copper consists of only one kind of atom, then it\ncannot be broken down into simpler substances, that is, into substances composed of fewer types of atoms.\nAnd if atoms are neither created nor destroyed during a chemical change, then the total mass of matter\npresent when matter changes from one type to another will remain constant (the law of conservation of\nmatter).\n"]], ["block_1", [" Testing Dalton\u2019s Atomic Theory \n"]], ["block_2", ["In the following drawing, the green spheres represent atoms of a certain element. The purple spheres\nrepresent atoms of another element. If the spheres touch, they are part of a single unit of a compound. Does\nthe following chemical change represented by these symbols violate any of the ideas of Dalton\u2019s atomic theory?\nIf so, which one?\n"]], ["block_3", ["5.\nAtoms are neither created nor destroyed during a chemical change, but are instead rearranged to yield\nsubstances that are different from those present before the change (Figure 2.4).\n"]], ["block_4", [" FIGURE 2.3 \nCopper(II) oxide, a powdery, black compound, results from the combination of two types of\n"]], ["block_5", ["atoms\u2014copper (brown spheres) and oxygen (red spheres)\u2014in a 1:1 ratio. (credit: modification of work by\n\u201cChemicalinterest\u201d/Wikimedia Commons)\n"]], ["block_6", [" FIGURE 2.4 \nWhen the elements copper (a shiny, red-brown solid, shown here as brown spheres) and oxygen\n"]], ["block_7", ["(a clear and colorless gas, shown here as red spheres) react, their atoms rearrange to form a compound\ncontaining copper and oxygen (a powdery, black solid). (credit copper: modification of work by http://images-of-\nelements.com/copper.php)\n"]], ["block_8", [{"image_0": "76_0.png", "coords": [99, 248, 531, 484]}]], ["block_9", ["EXAMPLE 2.1\n"]], ["block_10", [{"image_1": "76_1.png", "coords": [198, 57, 432, 176]}]], ["block_11", [" 2.1 \u2022 Early Ideas in Atomic Theory \n 63 \n"]]], "page_77": [["block_0", [" 64 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", ["Dalton knew of the experiments of French chemist Joseph Proust, who demonstrated that all samples of a pure\ncompound contain the same elements in the same proportion by mass. This statement is known as the law of \n definite proportions or the law of constant composition . The suggestion that the numbers of atoms of the\nelements in a given compound always exist in the same ratio is consistent with these observations. For\nexample, when different samples of isooctane (a component of gasoline and one of the standards used in the\noctane rating system) are analyzed, they are found to have a carbon-to-hydrogen mass ratio of 5.33:1, as\nshown in Table 2.1.\n"]], ["block_2", ["Dalton also used data from Proust, as well as results from his own experiments, to formulate another\ninteresting law. The law of multiple proportions states that when two elements react to form more than one\ncompound, a fixed mass of one element will react with masses of the other element in a ratio of small, whole\n"]], ["block_3", [{"image_0": "77_0.png", "coords": [72, 57, 306, 95]}]], ["block_4", [" Solution \n"]], ["block_5", ["The starting materials consist of two green spheres and two purple spheres. The products consist of only one\ngreen sphere and one purple sphere. This violates Dalton\u2019s postulate that atoms are neither created nor\ndestroyed during a chemical change, but are merely redistributed. (In this case, atoms appear to have been\ndestroyed.)\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["In the following drawing, the green spheres represent atoms of a certain element. The purple spheres\nrepresent atoms of another element. If the spheres touch, they are part of a single unit of a compound. Does\nthe following chemical change represented by these symbols violate any of the ideas of Dalton\u2019s atomic theory?\nIf so, which one?\n"]], ["block_8", [{"image_1": "77_1.png", "coords": [72, 242, 432, 281]}]], ["block_9", [" Answer: \nThe starting materials consist of four green spheres and two purple spheres. The products consist of four\ngreen spheres and two purple spheres. This does not violate any of Dalton\u2019s postulates: Atoms are neither\ncreated nor destroyed, but are redistributed in small, whole-number ratios.\n"]], ["block_10", ["It is worth noting that although all samples of a particular compound have the same mass ratio, the converse is\nnot true in general. That is, samples that have the same mass ratio are not necessarily the same substance. For\nexample, there are many compounds other than isooctane that also have a carbon-to-hydrogen mass ratio of\n5.33:1.00.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", [" TABLE 2.1 \n"]], ["block_13", [" Sample \n Carbon \n Hydrogen \n Mass Ratio \n"]], ["block_14", ["A\n14.82 g\n2.78 g\n"]], ["block_15", ["B\n22.33 g\n4.19 g\n"]], ["block_16", ["C\n19.40 g\n3.64 g\n"]], ["block_17", ["Constant Composition of Isooctane\n"]]], "page_78": [["block_0", ["numbers. For example, copper and chlorine can form a green, crystalline solid with a mass ratio of 0.558 g\nchlorine to 1 g copper, as well as a brown crystalline solid with a mass ratio of 1.116 g chlorine to 1 g copper.\nThese ratios by themselves may not seem particularly interesting or informative; however, if we take a ratio of\nthese ratios, we obtain a useful and possibly surprising result: a small, whole-number ratio.\n"]], ["block_1", ["This 2-to-1 ratio means that the brown compound has twice the amount of chlorine per amount of copper as\nthe green compound.\n"]], ["block_2", ["This can be explained by atomic theory if the copper-to-chlorine ratio in the brown compound is 1 copper\natom to 2 chlorine atoms, and the ratio in the green compound is 1 copper atom to 1 chlorine atom. The ratio\nof chlorine atoms (and thus the ratio of their masses) is therefore 2 to 1 (Figure 2.5).\n"]], ["block_3", [{"image_0": "78_0.png", "coords": [72, 236, 540, 411]}]], ["block_4", [" FIGURE 2.5 \nCompared to the copper chlorine compound in (a), where copper is represented by brown spheres and\n"]], ["block_5", ["chlorine by green spheres, the copper chlorine compound in (b) has twice as many chlorine atoms per copper atom.\n(credit a: modification of work by \u201cBenjah-bmm27\u201d/Wikimedia Commons; credit b: modification of work by\n\u201cWalkerma\u201d/Wikimedia Commons)\n"]], ["block_6", [" Laws of Definite and Multiple Proportions \n"]], ["block_7", ["A sample of compound A (a clear, colorless gas) is analyzed and found to contain 4.27 g carbon and 5.69 g\noxygen. A sample of compound B (also a clear, colorless gas) is analyzed and found to contain 5.19 g carbon\nand 13.84 g oxygen. Are these data an example of the law of definite proportions, the law of multiple\nproportions, or neither? What do these data tell you about substances A and B?\n"]], ["block_8", [" Solution \n"]], ["block_9", ["In compound A, the mass ratio of oxygen to carbon is:\n"]], ["block_10", ["In compound B, the mass ratio of oxygen to carbon is:\n"]], ["block_11", ["The ratio of these ratios is:\n"]], ["block_12", ["EXAMPLE 2.2\n"]], ["block_13", [" 2.1 \u2022 Early Ideas in Atomic Theory \n 65 \n"]]], "page_79": [["block_0", [" 66 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", ["This supports the law of multiple proportions. This means that A and B are different compounds, with A having\none-half as much oxygen per amount of carbon (or twice as much carbon per amount of oxygen) as B. A\npossible pair of compounds that would fit this relationship would be A = CO and B = CO2.\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["A sample of compound X (a clear, colorless, combustible liquid with a noticeable odor) is analyzed and found to\ncontain 14.13 g carbon and 2.96 g hydrogen. A sample of compound Y (a clear, colorless, combustible liquid\nwith a noticeable odor that is slightly different from X\u2019s odor) is analyzed and found to contain 19.91 g carbon\nand 3.34 g hydrogen. Are these data an example of the law of definite proportions, the law of multiple\nproportions, or neither? What do these data tell you about substances X and Y?\n"]], ["block_4", [" Answer: \n"]], ["block_5", ["In compound X, the mass ratio of carbon to hydrogen is\nIn compound Y, the mass ratio of carbon to\n"]], ["block_6", ["hydrogen is\nThe ratio of these ratios is\nThis small, whole-\n"]], ["block_7", ["number ratio supports the law of multiple proportions. This means that X and Y are different compounds.\n"]], ["block_8", [" 2.2 Evolution of Atomic Theory \n"]], ["block_9", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_10", ["If matter is composed of atoms, what are atoms composed of? Are they the smallest particles, or is there\nsomething smaller? In the late 1800s, a number of scientists interested in questions like these investigated the\nelectrical discharges that could be produced in low-pressure gases, with the most significant discovery made\nby English physicist J. J. Thomson using a cathode ray tube. This apparatus consisted of a sealed glass tube\nfrom which almost all the air had been removed; the tube contained two metal electrodes. When high voltage\nwas applied across the electrodes, a visible beam called a cathode ray appeared between them. This beam was\ndeflected toward the positive charge and away from the negative charge, and was produced in the same way\nwith identical properties when different metals were used for the electrodes. In similar experiments, the ray\nwas simultaneously deflected by an applied magnetic field, and measurements of the extent of deflection and\nthe magnetic field strength allowed Thomson to calculate the charge-to-mass ratio of the cathode ray particles.\nThe results of these measurements indicated that these particles were much lighter than atoms (Figure 2.6).\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["\u2022\nOutline milestones in the development of modern atomic theory\n"]], ["block_13", ["\u2022\nSummarize and interpret the results of the experiments of Thomson, Millikan, and Rutherford\n"]], ["block_14", ["\u2022\nDescribe the three subatomic particles that compose atoms\n"]], ["block_15", ["\u2022\nDefine isotopes and give examples for several elements\n"]]], "page_80": [["block_0", [{"image_0": "80_0.png", "coords": [72, 57, 540, 385]}]], ["block_1", [" FIGURE 2.6 \n(a) J. J. Thomson produced a visible beam in a cathode ray tube. (b) This is an early cathode ray tube,\n"]], ["block_2", ["invented in 1897 by Ferdinand Braun. (c) In the cathode ray, the beam (shown in yellow) comes from the cathode\nand is accelerated past the anode toward a fluorescent scale at the end of the tube. Simultaneous deflections by\napplied electric and magnetic fields permitted Thomson to calculate the mass-to-charge ratio of the particles\ncomposing the cathode ray. (credit a: modification of work by Nobel Foundation; credit b: modification of work by\nEugen Nesper; credit c: modification of work by \u201cKurzon\u201d/Wikimedia Commons)\n"]], ["block_3", ["Based on his observations, here is what Thomson proposed and why: The particles are attracted by positive (+)\ncharges and repelled by negative (\u2212) charges, so they must be negatively charged (like charges repel and unlike\ncharges attract); they are less massive than atoms and indistinguishable, regardless of the source material, so\nthey must be fundamental, subatomic constituents of all atoms. Although controversial at the time, Thomson\u2019s\nidea was gradually accepted, and his cathode ray particle is what we now call an electron , a negatively\ncharged, subatomic particle with a mass more than one thousand-times less that of an atom. The term\n\u201celectron\u201d was coined in 1891 by Irish physicist George Stoney, from \u201celectric ion.\u201d\n"]], ["block_4", ["Click here (http://openstax.org/l/16JJThomson) to hear Thomson describe his discovery in his own voice.\n"]], ["block_5", ["In 1909, more information about the electron was uncovered by American physicist Robert A. Millikan via his\n\u201coil drop\u201d experiments. Millikan created microscopic oil droplets, which could be electrically charged by\nfriction as they formed or by using X-rays. These droplets initially fell due to gravity, but their downward\nprogress could be slowed or even reversed by an electric field lower in the apparatus. By adjusting the electric\nfield strength and making careful measurements and appropriate calculations, Millikan was able to determine\nthe charge on individual drops (Figure 2.7).\n"]], ["block_6", ["LINK TO LEARNING\n"]], ["block_7", [" 2.2 \u2022 Evolution of Atomic Theory \n 67 \n"]]], "page_81": [["block_0", [" 68 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", [{"image_0": "81_0.png", "coords": [72, 57, 540, 306]}]], ["block_2", [" FIGURE 2.7 \nMillikan\u2019s experiment measured the charge of individual oil drops. The tabulated data are examples of\n"]], ["block_3", ["a few possible values.\n"]], ["block_4", ["Looking at the charge data that Millikan gathered, you may have recognized that the charge of an oil droplet is\nalways a multiple of a specific charge, 1.6\n10C. Millikan concluded that this value must therefore be a\n"]], ["block_5", ["fundamental charge\u2014the charge of a single electron\u2014with his measured charges due to an excess of one\nelectron (1 times 1.6\n10C), two electrons (2 times 1.6\n10C), three electrons (3 times 1.6\n10C),\n"]], ["block_6", ["and so on, on a given oil droplet. Since the charge of an electron was now known due to Millikan\u2019s research,\nand the charge-to-mass ratio was already known due to Thomson\u2019s research (1.759\n10C/kg), it only\n"]], ["block_7", ["required a simple calculation to determine the mass of the electron as well.\n"]], ["block_8", ["Scientists had now established that the atom was not indivisible as Dalton had believed, and due to the work of\nThomson, Millikan, and others, the charge and mass of the negative, subatomic particles\u2014the electrons\u2014were\nknown. However, the positively charged part of an atom was not yet well understood. In 1904, Thomson\nproposed the \u201cplum pudding\u201d model of atoms, which described a positively charged mass with an equal\namount of negative charge in the form of electrons embedded in it, since all atoms are electrically neutral. A\ncompeting model had been proposed in 1903 by Hantaro Nagaoka, who postulated a Saturn-like atom,\nconsisting of a positively charged sphere surrounded by a halo of electrons (Figure 2.8).\n"]], ["block_9", [{"image_1": "81_1.png", "coords": [72, 560, 540, 702]}]], ["block_10", [" FIGURE 2.8 \n(a) Thomson suggested that atoms resembled plum pudding, an English dessert consisting of moist\n"]], ["block_11", ["cake with embedded raisins (\u201cplums\u201d). (b) Nagaoka proposed that atoms resembled the planet Saturn, with a ring of\n"]], ["block_12", [" Access for free at openstax.org \n"]]], "page_82": [["block_0", ["electrons surrounding a positive \u201cplanet.\u201d (credit a: modification of work by \u201cMan vyi\u201d/Wikimedia Commons; credit\nb: modification of work by \u201cNASA\u201d/Wikimedia Commons)\n"]], ["block_1", ["The next major development in understanding the atom came from Ernest Rutherford, a physicist from New\nZealand who largely spent his scientific career in Canada and England. He performed a series of experiments\nusing a beam of high-speed, positively charged alpha particles ( \u03b1 particles) that were produced by the\nradioactive decay of radium; \u03b1 particles consist of two protons and two neutrons (you will learn more about\nradioactive decay in the chapter on nuclear chemistry). Rutherford and his colleagues Hans Geiger (later\nfamous for the Geiger counter) and Ernest Marsden aimed a beam of \u03b1 particles, the source of which was\nembedded in a lead block to absorb most of the radiation, at a very thin piece of gold foil and examined the\nresultant scattering of the \u03b1 particles using a luminescent screen that glowed briefly where hit by an \u03b1 particle.\n"]], ["block_2", ["What did they discover? Most particles passed right through the foil without being deflected at all. However,\nsome were diverted slightly, and a very small number were deflected almost straight back toward the source\n(Figure 2.9). Rutherford described finding these results: \u201cIt was quite the most incredible event that has ever\nhappened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper\nand it came back and hit you.\u201d\n"]], ["block_3", [{"image_0": "82_0.png", "coords": [72, 265, 540, 470]}]], ["block_4", [" FIGURE 2.9 \nGeiger and Rutherford fired \u03b1 particles at a piece of gold foil and detected where those particles went,\n"]], ["block_5", ["as shown in this schematic diagram of their experiment. Most of the particles passed straight through the foil, but a\nfew were deflected slightly and a very small number were significantly deflected.\n"]], ["block_6", ["Here is what Rutherford deduced: Because most of the fast-moving \u03b1 particles passed through the gold atoms\nundeflected, they must have traveled through essentially empty space inside the atom. Alpha particles are\npositively charged, so deflections arose when they encountered another positive charge (like charges repel\neach other). Since like charges repel one another, the few positively charged \u03b1 particles that changed paths\nabruptly must have hit, or closely approached, another body that also had a highly concentrated, positive\ncharge. Since the deflections occurred a small fraction of the time, this charge only occupied a small amount of\nthe space in the gold foil. Analyzing a series of such experiments in detail, Rutherford drew two conclusions:\n"]], ["block_7", ["View this simulation (http://openstax.org/l/16Rutherford) of the Rutherford gold foil experiment. Adjust the slit\nwidth to produce a narrower or broader beam of \u03b1 particles to see how that affects the scattering pattern.\n"]], ["block_8", ["1 Ernest Rutherford, \u201cThe Development of the Theory of Atomic Structure,\u201d ed. J. A. Ratcliffe, in Background to Modern Science,\neds. Joseph Needham and Walter Pagel, (Cambridge, UK: Cambridge University Press, 1938), 61\u201374. Accessed September 22, 2014,\nhttps://ia600508.us.archive.org/3/items/backgroundtomode032734mbp/backgroundtomode032734mbp.pdf.\n"]], ["block_9", ["1.\nThe volume occupied by an atom must consist of a large amount of empty space.\n"]], ["block_10", ["2.\nA small, relatively heavy, positively charged body, the nucleus , must be at the center of each atom.\n"]], ["block_11", ["LINK TO LEARNING\n"]], ["block_12", [" 2.2 \u2022 Evolution of Atomic Theory \n 69 \n"]]], "page_83": [["block_0", [" 70 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", ["This analysis led Rutherford to propose a model in which an atom consists of a very small, positively charged\nnucleus, in which most of the mass of the atom is concentrated, surrounded by the negatively charged\nelectrons, so that the atom is electrically neutral (Figure 2.10). After many more experiments, Rutherford also\ndiscovered that the nuclei of other elements contain the hydrogen nucleus as a \u201cbuilding block,\u201d and he named\nthis more fundamental particle the proton , the positively charged, subatomic particle found in the nucleus.\nWith one addition, which you will learn next, this nuclear model of the atom, proposed over a century ago, is\nstill used today.\n"]], ["block_2", [{"image_0": "83_0.png", "coords": [72, 152, 540, 426]}]], ["block_3", [" FIGURE 2.10 \nThe \u03b1 particles are deflected only when they collide with or pass close to the much heavier,\n"]], ["block_4", ["positively charged gold nucleus. Because the nucleus is very small compared to the size of an atom, very few \u03b1\nparticles are deflected. Most pass through the relatively large region occupied by electrons, which are too light to\ndeflect the rapidly moving particles.\n"]], ["block_5", ["The Rutherford Scattering simulation (http://openstax.org/l/16PhetScatter) allows you to investigate the\ndifferences between a \u201cplum pudding\u201d atom and a Rutherford atom by firing \u03b1 particles at each type of atom.\n"]], ["block_6", ["Another important finding was the discovery of isotopes. During the early 1900s, scientists identified several\nsubstances that appeared to be new elements, isolating them from radioactive ores. For example, a \u201cnew\nelement\u201d produced by the radioactive decay of thorium was initially given the name mesothorium. However, a\nmore detailed analysis showed that mesothorium was chemically identical to radium (another decay product),\ndespite having a different atomic mass. This result, along with similar findings for other elements, led the\nEnglish chemist Frederick Soddy to realize that an element could have types of atoms with different masses\nthat were chemically indistinguishable. These different types are called isotopes \u2014atoms of the same element\nthat differ in mass. Soddy was awarded the Nobel Prize in Chemistry in 1921 for this discovery.\n"]], ["block_7", ["One puzzle remained: The nucleus was known to contain almost all of the mass of an atom, with the number of\nprotons only providing half, or less, of that mass. Different proposals were made to explain what constituted\nthe remaining mass, including the existence of neutral particles in the nucleus. As you might expect, detecting\nuncharged particles is very challenging, and it was not until 1932 that James Chadwick found evidence of\n neutrons , uncharged, subatomic particles with a mass approximately the same as that of protons. The\nexistence of the neutron also explained isotopes: They differ in mass because they have different numbers of\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["LINK TO LEARNING\n"]]], "page_84": [["block_0", ["neutrons, but they are chemically identical because they have the same number of protons. This will be\nexplained in more detail later in this chapter.\n"]], ["block_1", [" 2.3 Atomic Structure and Symbolism \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["The development of modern atomic theory revealed much about the inner structure of atoms. It was learned\nthat an atom contains a very small nucleus composed of positively charged protons and uncharged neutrons,\nsurrounded by a much larger volume of space containing negatively charged electrons. The nucleus contains\nthe majority of an atom\u2019s mass because protons and neutrons are much heavier than electrons, whereas\nelectrons occupy almost all of an atom\u2019s volume. The diameter of an atom is on the order of 10m, whereas\nthe diameter of the nucleus is roughly 10m\u2014about 100,000 times smaller. For a perspective about their\nrelative sizes, consider this: If the nucleus were the size of a blueberry, the atom would be about the size of a\nfootball stadium (Figure 2.11).\n"]], ["block_4", [{"image_0": "84_0.png", "coords": [72, 289, 540, 433]}]], ["block_5", [" FIGURE 2.11 \nIf an atom could be expanded to the size of a football stadium, the nucleus would be the size of a\n"]], ["block_6", ["single blueberry. (credit middle: modification of work by \u201cbabyknight\u201d/Wikimedia Commons; credit right:\nmodification of work by Paxson Woelber)\n"]], ["block_7", ["Atoms\u2014and the protons, neutrons, and electrons that compose them\u2014are extremely small. For example, a\ncarbon atom weighs less than 2\n10g, and an electron has a charge of less than 2\n10C (coulomb).\n"]], ["block_8", ["When describing the properties of tiny objects such as atoms, we use appropriately small units of measure,\nsuch as the atomic mass unit (amu) and the fundamental unit of charge (e) . The amu was originally defined\nbased on hydrogen, the lightest element, then later in terms of oxygen. Since 1961, it has been defined with\nregard to the most abundant isotope of carbon, atoms of which are assigned masses of exactly 12 amu. (This\nisotope is known as \u201ccarbon-12\u201d as will be discussed later in this module.) Thus, one amu is exactly\nof the\n"]], ["block_9", ["mass of one carbon-12 atom: 1 amu = 1.6605\n10g. (The Dalton (Da) and the unified atomic mass unit (u) \n"]], ["block_10", ["are alternative units that are equivalent to the amu.) The fundamental unit of charge (also called the\nelementary charge) equals the magnitude of the charge of an electron (e) with e = 1.602\n10C.\n"]], ["block_11", ["A proton has a mass of 1.0073 amu and a charge of 1+. A neutron is a slightly heavier particle with a mass\n1.0087 amu and a charge of zero; as its name suggests, it is neutral. The electron has a charge of 1\u2212 and is a\nmuch lighter particle with a mass of about 0.00055 amu (it would take about 1800 electrons to equal the mass\nof one proton). The properties of these fundamental particles are summarized in Table 2.2. (An observant\nstudent might notice that the sum of an atom\u2019s subatomic particles does not equal the atom\u2019s actual mass: The\ntotal mass of six protons, six neutrons, and six electrons is 12.0993 amu, slightly larger than 12.00 amu. This\n\u201cmissing\u201d mass is known as the mass defect, and you will learn about it in the chapter on nuclear chemistry.)\n"]], ["block_12", ["\u2022\nWrite and interpret symbols that depict the atomic number, mass number, and charge of an atom or ion\n"]], ["block_13", ["\u2022\nDefine the atomic mass unit and average atomic mass\n"]], ["block_14", ["\u2022\nCalculate average atomic mass and isotopic abundance\n"]], ["block_15", [" 2.3 \u2022 Atomic Structure and Symbolism \n 71 \n"]]], "page_85": [["block_0", [" 72 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", ["The number of protons in the nucleus of an atom is its atomic number (Z) . This is the defining trait of an\nelement: Its value determines the identity of the atom. For example, any atom that contains six protons is the\nelement carbon and has the atomic number 6, regardless of how many neutrons or electrons it may have. A\nneutral atom must contain the same number of positive and negative charges, so the number of protons equals\nthe number of electrons. Therefore, the atomic number also indicates the number of electrons in an atom. The\ntotal number of protons and neutrons in an atom is called its mass number (A) . The number of neutrons is\ntherefore the difference between the mass number and the atomic number: A \u2013 Z = number of neutrons.\n"]], ["block_2", ["Atoms are electrically neutral if they contain the same number of positively charged protons and negatively\ncharged electrons. When the numbers of these subatomic particles are not equal, the atom is electrically\ncharged and is called an ion . The charge of an atom is defined as follows:\n"]], ["block_3", ["Atomic charge = number of protons \u2212 number of electrons\n"]], ["block_4", ["As will be discussed in more detail later in this chapter, atoms (and molecules) typically acquire charge by\ngaining or losing electrons. An atom that gains one or more electrons will exhibit a negative charge and is\ncalled an anion . Positively charged atoms called cations are formed when an atom loses one or more\nelectrons. For example, a neutral sodium atom (Z = 11) has 11 electrons. If this atom loses one electron, it will\nbecome a cation with a 1+ charge (11 \u2212 10 = 1+). A neutral oxygen atom (Z = 8) has eight electrons, and if it\ngains two electrons it will become an anion with a 2\u2212 charge (8 \u2212 10 = 2\u2212).\n"]], ["block_5", [" Composition of an Atom \n"]], ["block_6", ["Iodine is an essential trace element in our diet; it is needed to produce thyroid hormone. Insufficient iodine in\nthe diet can lead to the development of a goiter, an enlargement of the thyroid gland (Figure 2.12).\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [" TABLE 2.2 \n"]], ["block_9", ["EXAMPLE 2.3\n"]], ["block_10", ["electron\noutside nucleus\n\u22121.602\n10\n1\u2212\n0.00055\n0.00091\n10\n"]], ["block_11", ["neutron\nnucleus\n0\n0\n1.00866\n1.67493\n10\n"]], ["block_12", ["proton\nnucleus\n1.602\n10\n1+\n1.00727\n1.67262\n10\n"]], ["block_13", [" Name \n Location \n Charge (C) \n Unit Charge \n Mass (amu) \n Mass (g) \n"]], ["block_14", ["Properties of Subatomic Particles\n"]]], "page_86": [["block_0", [" FIGURE 2.12 \n(a) Insufficient iodine in the diet can cause an enlargement of the thyroid gland called a goiter. (b)\n"]], ["block_1", ["The addition of small amounts of iodine to salt, which prevents the formation of goiters, has helped eliminate this\nconcern in the US where salt consumption is high. (credit a: modification of work by \u201cAlmazi\u201d/Wikimedia Commons;\ncredit b: modification of work by Mike Mozart)\n"]], ["block_2", ["The addition of small amounts of iodine to table salt (iodized salt) has essentially eliminated this health\nconcern in the United States, but as much as 40% of the world\u2019s population is still at risk of iodine deficiency.\nThe iodine atoms are added as anions, and each has a 1\u2212 charge and a mass number of 127. Determine the\nnumbers of protons, neutrons, and electrons in one of these iodine anions.\n"]], ["block_3", [" Solution \n"]], ["block_4", ["The atomic number of iodine (53) tells us that a neutral iodine atom contains 53 protons in its nucleus and 53\nelectrons outside its nucleus. Because the sum of the numbers of protons and neutrons equals the mass\nnumber, 127, the number of neutrons is 74 (127 \u2212 53 = 74). Since the iodine is added as a 1\u2212 anion, the\nnumber of electrons is 54 [53 \u2013 (1\u2013) = 54].\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["An ion of platinum has a mass number of 195 and contains 74 electrons. How many protons and neutrons\ndoes it contain, and what is its charge?\n"]], ["block_7", [" Answer: \n78 protons; 117 neutrons; charge is 4+\n"]], ["block_8", [" Chemical Symbols \n"]], ["block_9", ["A chemical symbol is an abbreviation that we use to indicate an element or an atom of an element. For\nexample, the symbol for mercury is Hg (Figure 2.13). We use the same symbol to indicate one atom of mercury\n(microscopic domain) or to label a container of many atoms of the element mercury (macroscopic domain).\n"]], ["block_10", [{"image_0": "86_0.png", "coords": [130, 57, 481, 213]}]], ["block_11", [" 2.3 \u2022 Atomic Structure and Symbolism \n 73 \n"]]], "page_87": [["block_0", [" 74 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", [" FIGURE 2.13 \nThe symbol Hg represents the element mercury regardless of the amount; it could represent one\n"]], ["block_2", ["atom of mercury or a large amount of mercury.\n"]], ["block_3", ["The symbols for several common elements and their atoms are listed in Table 2.3. Some symbols are derived\nfrom the common name of the element; others are abbreviations of the name in another language. Most\nsymbols have one or two letters, but three-letter symbols have been used to describe some elements that have\natomic numbers greater than 112. To avoid confusion with other notations, only the first letter of a symbol is\ncapitalized. For example, Co is the symbol for the element cobalt, but CO is the notation for the compound\ncarbon monoxide, which contains atoms of the elements carbon (C) and oxygen (O). All known elements and\ntheir symbols are in the periodic table in Figure 2.26 (also found in Appendix A).\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", [" TABLE 2.3 \n"]], ["block_6", [" Element \n Symbol \n Element \n Symbol \n"]], ["block_7", ["aluminum\nAl\niron\nFe (from ferrum)\n"]], ["block_8", ["bromine\nBr\nlead\nPb (from plumbum)\n"]], ["block_9", ["calcium\nCa\nmagnesium\nMg\n"]], ["block_10", ["carbon\nC\nmercury\nHg (from hydrargyrum)\n"]], ["block_11", ["chlorine\nCl\nnitrogen\nN\n"]], ["block_12", ["chromium\nCr\noxygen\nO\n"]], ["block_13", ["cobalt\nCo\npotassium\nK (from kalium)\n"]], ["block_14", ["copper\nCu (from cuprum)\nsilicon\nSi\n"]], ["block_15", ["fluorine\nF\nsilver\nAg (from argentum)\n"]], ["block_16", ["gold\nAu (from aurum)\nsodium\nNa (from natrium)\n"]], ["block_17", ["helium\nHe\nsulfur\nS\n"]], ["block_18", [{"image_0": "87_0.png", "coords": [189, 57, 423, 244]}]], ["block_19", ["Some Common Elements and Their Symbols\n"]]], "page_88": [["block_0", ["Traditionally, the discoverer (or discoverers) of a new element names the element. However, until the name is\nrecognized by the International Union of Pure and Applied Chemistry (IUPAC), the recommended name of the\nnew element is based on the Latin word(s) for its atomic number. For example, element 106 was called\nunnilhexium (Unh), element 107 was called unnilseptium (Uns), and element 108 was called unniloctium\n(Uno) for several years. These elements are now named after scientists (or occasionally locations); for example,\nelement 106 is now known as seaborgium (Sg) in honor of Glenn Seaborg, a Nobel Prize winner who was active\nin the discovery of several heavy elements. Element 109 was named in honor of Lise Meitner, who discovered\nnuclear fission, a phenomenon that would have world-changing impacts; Meitner also contributed to the\ndiscovery of some major isotopes, discussed immediately below.\n"]], ["block_1", ["Visit this site (http://openstax.org/l/16IUPAC) to learn more about IUPAC, the International Union of Pure and\nApplied Chemistry, and explore its periodic table.\n"]], ["block_2", [" Isotopes \n"]], ["block_3", ["The symbol for a specific isotope of any element is written by placing the mass number as a superscript to the\nleft of the element symbol (Figure 2.14). The atomic number is sometimes written as a subscript preceding the\nsymbol, but since this number defines the element\u2019s identity, as does its symbol, it is often omitted. For\nexample, magnesium exists as a mixture of three isotopes, each with an atomic number of 12 and with mass\nnumbers of 24, 25, and 26, respectively. These isotopes can be identified as Mg, Mg, and Mg. These\nisotope symbols are read as \u201celement, mass number\u201d and can be symbolized consistent with this reading. For\ninstance, Mg is read as \u201cmagnesium 24,\u201d and can be written as \u201cmagnesium-24\u201d or \u201cMg-24.\u201d Mg is read as\n\u201cmagnesium 25,\u201d and can be written as \u201cmagnesium-25\u201d or \u201cMg-25.\u201d All magnesium atoms have 12 protons in\ntheir nucleus. They differ only because a Mg atom has 12 neutrons in its nucleus, a Mg atom has 13\nneutrons, and a Mg has 14 neutrons.\n"]], ["block_4", [" FIGURE 2.14 \nThe symbol for an atom indicates the element via its usual two-letter symbol, the mass number as a\n"]], ["block_5", ["left superscript, the atomic number as a left subscript (sometimes omitted), and the charge as a right superscript.\n"]], ["block_6", ["Information about the naturally occurring isotopes of elements with atomic numbers 1 through 10 is given in\nTable 2.4. Note that in addition to standard names and symbols, the isotopes of hydrogen are often referred to\nusing common names and accompanying symbols. Hydrogen-2, symbolized H, is also called deuterium and\nsometimes symbolized D. Hydrogen-3, symbolized H, is also called tritium and sometimes symbolized T.\n"]], ["block_7", ["LINK TO LEARNING\n"]], ["block_8", [" TABLE 2.3 \n"]], ["block_9", [" Element \n Symbol \n Element \n Symbol \n"]], ["block_10", ["hydrogen\nH\ntin\nSn (from stannum)\n"]], ["block_11", ["iodine\nI\nzinc\nZn\n"]], ["block_12", [{"image_0": "88_0.png", "coords": [189, 505, 423, 557]}]], ["block_13", [" 2.3 \u2022 Atomic Structure and Symbolism \n 75 \n"]]], "page_89": [["block_0", [" 76 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", [" TABLE 2.4 \n"]], ["block_2", [" Access for free at openstax.org \n"]], ["block_3", [" Element \n Symbol \n Atomic \n Number \n"]], ["block_4", ["hydrogen\n"]], ["block_5", ["beryllium\n4\n4\n5\n9.0122\n100\n"]], ["block_6", ["boron\n"]], ["block_7", ["carbon\n"]], ["block_8", ["fluorine\n9\n9\n10\n18.9984\n100\n"]], ["block_9", ["neon\n10\n10\n10\n19.9924\n90.48\n"]], ["block_10", ["nitrogen\n"]], ["block_11", ["lithium\n"]], ["block_12", ["helium\n"]], ["block_13", ["oxygen\n"]], ["block_14", ["(deuterium)\n1\n1\n1\n2.0141\n0.0115\n"]], ["block_15", ["(protium)\n1\n1\n0\n1.0078\n99.989\n"]], ["block_16", ["(tritium)\n1\n1\n2\n3.01605\n\u2014 (trace)\n"]], ["block_17", ["Nuclear Compositions of Atoms of the Very Light Elements\n"]], ["block_18", ["2\n2\n1\n3.01603\n0.00013\n"]], ["block_19", ["2\n2\n2\n4.0026\n100\n"]], ["block_20", ["3\n3\n3\n6.0151\n7.59\n"]], ["block_21", ["3\n3\n4\n7.0160\n92.41\n"]], ["block_22", ["5\n5\n5\n10.0129\n19.9\n"]], ["block_23", ["5\n5\n6\n11.0093\n80.1\n"]], ["block_24", ["6\n6\n6\n12.0000\n98.89\n"]], ["block_25", ["6\n6\n7\n13.0034\n1.11\n"]], ["block_26", ["6\n6\n8\n14.0032\n\u2014 (trace)\n"]], ["block_27", ["7\n7\n7\n14.0031\n99.63\n"]], ["block_28", ["7\n7\n8\n15.0001\n0.37\n"]], ["block_29", ["8\n8\n8\n15.9949\n99.757\n"]], ["block_30", ["8\n8\n9\n16.9991\n0.038\n"]], ["block_31", ["8\n8\n10\n17.9992\n0.205\n"]], ["block_32", [" Number of \n Protons \n"]], ["block_33", [" Number of \n Neutrons \n"]], ["block_34", [" Mass \n (amu) \n"]], ["block_35", [" % Natural \n Abundance \n"]]], "page_90": [["block_0", [" TABLE 2.4 \n"]], ["block_1", ["Use this Build an Atom simulator (http://openstax.org/l/16PhetAtomBld) to build atoms of the first 10\nelements, see which isotopes exist, check nuclear stability, and gain experience with isotope symbols.\n"]], ["block_2", [" Atomic Mass \n"]], ["block_3", ["Because each proton and each neutron contribute approximately one amu to the mass of an atom, and each\nelectron contributes far less, the atomic mass of a single atom is approximately equal to its mass number (a\nwhole number). However, the average masses of atoms of most elements are not whole numbers because most\nelements exist naturally as mixtures of two or more isotopes.\n"]], ["block_4", ["The mass of an element shown in a periodic table or listed in a table of atomic masses is a weighted, average\nmass of all the isotopes present in a naturally occurring sample of that element. This is equal to the sum of\neach individual isotope\u2019s mass multiplied by its fractional abundance.\n"]], ["block_5", ["For example, the element boron is composed of two isotopes: About 19.9% of all boron atoms are B with a\nmass of 10.0129 amu, and the remaining 80.1% are B with a mass of 11.0093 amu. The average atomic mass\nfor boron is calculated to be:\n"]], ["block_6", ["It is important to understand that no single boron atom weighs exactly 10.8 amu; 10.8 amu is the average mass\nof all boron atoms, and individual boron atoms weigh either approximately 10 amu or 11 amu.\n"]], ["block_7", [" Calculation of Average Atomic Mass \n"]], ["block_8", ["A meteorite found in central Indiana contains traces of the noble gas neon picked up from the solar wind\nduring the meteorite\u2019s trip through the solar system. Analysis of a sample of the gas showed that it consisted of\n91.84% Ne (mass 19.9924 amu), 0.47% Ne (mass 20.9940 amu), and 7.69% Ne (mass 21.9914 amu).\nWhat is the average mass of the neon in the solar wind?\n"]], ["block_9", [" Solution \n"]], ["block_10", ["The average mass of a neon atom in the solar wind is 20.15 amu. (The average mass of a terrestrial neon atom\nis 20.1796 amu. This result demonstrates that we may find slight differences in the natural abundance of\n"]], ["block_11", [" Element \n Symbol \n Atomic \n Number \n"]], ["block_12", ["LINK TO LEARNING\n"]], ["block_13", ["EXAMPLE 2.4\n"]], ["block_14", ["10\n10\n11\n20.9938\n0.27\n"]], ["block_15", ["10\n10\n12\n21.9914\n9.25\n"]], ["block_16", [" Number of \n Protons \n"]], ["block_17", [" Number of \n Neutrons \n"]], ["block_18", [" 2.3 \u2022 Atomic Structure and Symbolism \n 77 \n"]], ["block_19", [" Mass \n (amu) \n"]], ["block_20", [" % Natural \n Abundance \n"]]], "page_91": [["block_0", [" 78 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", ["isotopes, depending on their origin.)\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["A sample of magnesium is found to contain 78.70% of Mg atoms (mass 23.98 amu), 10.13% of Mg atoms\n(mass 24.99 amu), and 11.17% of Mg atoms (mass 25.98 amu). Calculate the average mass of a Mg atom.\n"]], ["block_4", [" Answer: \n24.31 amu\n"]], ["block_5", ["We can also do variations of this type of calculation, as shown in the next example.\n"]], ["block_6", [" Calculation of Percent Abundance \n"]], ["block_7", ["Naturally occurring chlorine consists of Cl (mass 34.96885 amu) and Cl (mass 36.96590 amu), with an\naverage mass of 35.453 amu. What is the percent composition of Cl in terms of these two isotopes?\n"]], ["block_8", [" Solution \n"]], ["block_9", ["The average mass of chlorine is the fraction that is Cl times the mass of Cl plus the fraction that is Cl\ntimes the mass of Cl.\n"]], ["block_10", ["If we let x represent the fraction that is Cl, then the fraction that is Cl is represented by 1.00 \u2212 x.\n"]], ["block_11", ["(The fraction that is Cl + the fraction that is Cl must add up to 1, so the fraction of Cl must equal 1.00 \u2212 the\nfraction of Cl.)\n"]], ["block_12", ["Substituting this into the average mass equation, we have:\n"]], ["block_13", ["So solving yields: x = 0.7576, which means that 1.00 \u2212 0.7576 = 0.2424. Therefore, chlorine consists of 75.76%\n35Cl and 24.24% 37Cl.\n"]], ["block_14", [" Check Your Learning \n"]], ["block_15", ["Naturally occurring copper consists of Cu (mass 62.9296 amu) and Cu (mass 64.9278 amu), with an\naverage mass of 63.546 amu. What is the percent composition of Cu in terms of these two isotopes?\n"]], ["block_16", [" Answer: \n69.15% Cu-63 and 30.85% Cu-65\n"]], ["block_17", ["Visit this site (http://openstax.org/l/16PhetAtomMass) to make mixtures of the main isotopes of the first 18\nelements, gain experience with average atomic mass, and check naturally occurring isotope ratios using the\nIsotopes and Atomic Mass simulation.\n"]], ["block_18", ["As you will learn, isotopes are important in nature and especially in human understanding of science and\nmedicine. Let's consider just one natural, stable isotope: Oxygen-18, which is noted in the table above and is\nreferred to as one of the environmental isotopes. It is important in paleoclimatology, for example, because\nscientists can use the ratio between Oxygen-18 and Oxygen-16 in an ice core to determine the temperature of\n"]], ["block_19", [" Access for free at openstax.org \n"]], ["block_20", ["LINK TO LEARNING\n"]], ["block_21", ["EXAMPLE 2.5\n"]]], "page_92": [["block_0", ["precipitation over time. Oxygen-18 was also critical to the discovery of metabolic pathways and the\nmechanisms of enzymes. Mildred Cohn pioneered the usage of these isotopes to act as tracers, so that\nresearchers could follow their path through reactions and gain a better understanding of what is happening.\nOne of her first discoveries provided insight into the phosphorylation of glucose that takes place in\nmitochondria. And the methods of using isotopes for this research contributed to entire fields of study.\n"]], ["block_1", ["The occurrence and natural abundances of isotopes can be experimentally determined using an instrument\ncalled a mass spectrometer. Mass spectrometry (MS) is widely used in chemistry, forensics, medicine,\nenvironmental science, and many other fields to analyze and help identify the substances in a sample of\nmaterial. In a typical mass spectrometer (Figure 2.15), the sample is vaporized and exposed to a high-energy\nelectron beam that causes the sample\u2019s atoms (or molecules) to become electrically charged, typically by losing\none or more electrons. These cations then pass through a (variable) electric or magnetic field that deflects each\ncation\u2019s path to an extent that depends on both its mass and charge (similar to how the path of a large steel ball\nrolling past a magnet is deflected to a lesser extent that that of a small steel ball). The ions are detected, and a\nplot of the relative number of ions generated versus their mass-to-charge ratios (a mass spectrum) is made.\nThe height of each vertical feature or peak in a mass spectrum is proportional to the fraction of cations with\nthe specified mass-to-charge ratio. Since its initial use during the development of modern atomic theory, MS\nhas evolved to become a powerful tool for chemical analysis in a wide range of applications.\n"]], ["block_2", [{"image_0": "92_0.png", "coords": [72, 284, 540, 502]}]], ["block_3", [" FIGURE 2.15 \nAnalysis of zirconium in a mass spectrometer produces a mass spectrum with peaks showing the\n"]], ["block_4", ["different isotopes of Zr.\n"]], ["block_5", ["See an animation (http://openstax.org/l/16MassSpec) that explains mass spectrometry. Watch this video\n(http://openstax.org/l/16RSChemistry) from the Royal Society for Chemistry for a brief description of the\nrudiments of mass spectrometry.\n"]], ["block_6", [" 2.4 Chemical Formulas \n"]], ["block_7", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_8", ["A molecular formula is a representation of a molecule that uses chemical symbols to indicate the types of\natoms followed by subscripts to show the number of atoms of each type in the molecule. (A subscript is used\nonly when more than one atom of a given type is present.) Molecular formulas are also used as abbreviations\n"]], ["block_9", ["\u2022\nSymbolize the composition of molecules using molecular formulas and empirical formulas\n"]], ["block_10", ["\u2022\nRepresent the bonding arrangement of atoms within molecules using structural formulas\n"]], ["block_11", ["LINK TO LEARNING\n"]], ["block_12", [" 2.4 \u2022 Chemical Formulas \n 79 \n"]]], "page_93": [["block_0", [" 80 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", ["for the names of compounds.\n"]], ["block_2", ["The structural formula for a compound gives the same information as its molecular formula (the types and\nnumbers of atoms in the molecule) but also shows how the atoms are connected in the molecule. The\nstructural formula for methane contains symbols for one C atom and four H atoms, indicating the number of\natoms in the molecule (Figure 2.16). The lines represent bonds that hold the atoms together. (A chemical bond\nis an attraction between atoms or ions that holds them together in a molecule or a crystal.) We will discuss\nchemical bonds and see how to predict the arrangement of atoms in a molecule later. For now, simply know\nthat the lines are an indication of how the atoms are connected in a molecule. A ball-and-stick model shows\nthe geometric arrangement of the atoms with atomic sizes not to scale, and a space-filling model shows the\nrelative sizes of the atoms.\n"]], ["block_3", [" FIGURE 2.16 \nA methane molecule can be represented as (a) a molecular formula, (b) a structural formula, (c) a\n"]], ["block_4", ["ball-and-stick model, and (d) a space-filling model. Carbon and hydrogen atoms are represented by black and white\nspheres, respectively.\n"]], ["block_5", ["Although many elements consist of discrete, individual atoms, some exist as molecules made up of two or\nmore atoms of the element chemically bonded together. For example, most samples of the elements hydrogen,\noxygen, and nitrogen are composed of molecules that contain two atoms each (called diatomic molecules) and\nthus have the molecular formulas H2, O2, and N2, respectively. Other elements commonly found as diatomic\nmolecules are fluorine (F2), chlorine (Cl2), bromine (Br2), and iodine (I2). The most common form of the\nelement sulfur is composed of molecules that consist of eight atoms of sulfur; its molecular formula is S8\n(Figure 2.17).\n"]], ["block_6", [" FIGURE 2.17 \nA molecule of sulfur is composed of eight sulfur atoms and is therefore written as S8. It can be\n"]], ["block_7", ["represented as (a) a structural formula, (b) a ball-and-stick model, and (c) a space-filling model. Sulfur atoms are\nrepresented by yellow spheres.\n"]], ["block_8", ["It is important to note that a subscript following a symbol and a number in front of a symbol do not represent\nthe same thing; for example, H2 and 2H represent distinctly different species. H2 is a molecular formula; it\nrepresents a diatomic molecule of hydrogen, consisting of two atoms of the element that are chemically\nbonded together. The expression 2H, on the other hand, indicates two separate hydrogen atoms that are not\ncombined as a unit. The expression 2H2 represents two molecules of diatomic hydrogen (Figure 2.18).\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", [{"image_0": "93_0.png", "coords": [130, 196, 481, 284]}]], ["block_11", [{"image_1": "93_1.png", "coords": [130, 425, 481, 510]}]], ["block_12", [{"image_2": "93_2.png", "coords": [130, 627, 481, 712]}]], ["block_13", [" FIGURE 2.18 \nThe symbols H, 2H, H2, and 2H2 represent very different entities.\n"]]], "page_94": [["block_0", ["Compounds are formed when two or more elements chemically combine, resulting in the formation of bonds.\nFor example, hydrogen and oxygen can react to form water, and sodium and chlorine can react to form table\nsalt. We sometimes describe the composition of these compounds with an empirical formula , which indicates\nthe types of atoms present and the simplest whole-number ratio of the number of atoms (or ions) in the\ncompound. For example, titanium dioxide (used as pigment in white paint and in the thick, white, blocking\ntype of sunscreen) has an empirical formula of TiO2. This identifies the elements titanium (Ti) and oxygen (O)\nas the constituents of titanium dioxide, and indicates the presence of twice as many atoms of the element\noxygen as atoms of the element titanium (Figure 2.19).\n"]], ["block_1", [" FIGURE 2.19 \n(a) The white compound titanium dioxide provides effective protection from the sun. (b) A crystal of\n"]], ["block_2", ["titanium dioxide, TiO2, contains titanium and oxygen in a ratio of 1 to 2. The titanium atoms are gray and the oxygen\natoms are red. (credit a: modification of work by \u201cosseous\u201d/Flickr)\n"]], ["block_3", ["As discussed previously, we can describe a compound with a molecular formula, in which the subscripts\nindicate the actual numbers of atoms of each element in a molecule of the compound. In many cases, the\nmolecular formula of a substance is derived from experimental determination of both its empirical formula\nand its molecular mass (the sum of atomic masses for all atoms composing the molecule). For example, it can\nbe determined experimentally that benzene contains two elements, carbon (C) and hydrogen (H), and that for\nevery carbon atom in benzene, there is one hydrogen atom. Thus, the empirical formula is CH. An\nexperimental determination of the molecular mass reveals that a molecule of benzene contains six carbon\natoms and six hydrogen atoms, so the molecular formula for benzene is C6H6 (Figure 2.20).\n"]], ["block_4", [{"image_0": "94_0.png", "coords": [72, 465, 540, 571]}]], ["block_5", [" FIGURE 2.20 \nBenzene, C6H6, is produced during oil refining and has many industrial uses. A benzene molecule can\n"]], ["block_6", ["be represented as (a) a structural formula, (b) a ball-and-stick model, and (c) a space-filling model. (d) Benzene is a\nclear liquid. (credit d: modification of work by Sahar Atwa)\n"]], ["block_7", ["If we know a compound\u2019s formula, we can easily determine the empirical formula. (This is somewhat of an\nacademic exercise; the reverse chronology is generally followed in actual practice.) For example, the molecular\nformula for acetic acid, the component that gives vinegar its sharp taste, is C2H4O2. This formula indicates that\na molecule of acetic acid (Figure 2.21) contains two carbon atoms, four hydrogen atoms, and two oxygen atoms.\nThe ratio of atoms is 2:4:2. Dividing by the lowest common denominator (2) gives the simplest, whole-number\nratio of atoms, 1:2:1, so the empirical formula is CH2O. Note that a molecular formula is always a whole-\nnumber multiple of an empirical formula.\n"]], ["block_8", [{"image_1": "94_1.png", "coords": [130, 164, 481, 311]}]], ["block_9", [" 2.4 \u2022 Chemical Formulas \n 81 \n"]]], "page_95": [["block_0", [" 82 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", [" FIGURE 2.21 \n(a) Vinegar contains acetic acid, C2H4O2, which has an empirical formula of CH2O. It can be\n"]], ["block_2", ["represented as (b) a structural formula and (c) as a ball-and-stick model. (credit a: modification of work by\n\u201cHomeSpot HQ\u201d/Flickr)\n"]], ["block_3", [" Empirical and Molecular Formulas \n"]], ["block_4", ["Molecules of glucose (blood sugar) contain 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms. What are\nthe molecular and empirical formulas of glucose?\n"]], ["block_5", [" Solution \n"]], ["block_6", ["The molecular formula is C6H12O6 because one molecule actually contains 6 C, 12 H, and 6 O atoms. The\nsimplest whole-number ratio of C to H to O atoms in glucose is 1:2:1, so the empirical formula is CH2O.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["A molecule of metaldehyde (a pesticide used for snails and slugs) contains 8 carbon atoms, 16 hydrogen atoms,\nand 4 oxygen atoms. What are the molecular and empirical formulas of metaldehyde?\n"]], ["block_9", [" Answer: \nMolecular formula, C8H16O4; empirical formula, C2H4O\n"]], ["block_10", ["You can explore molecule building (http://openstax.org/l/16molbuilding) using an online simulation.\n"]], ["block_11", ["2 Lee Cronin, \u201cPrint Your Own Medicine,\u201d Talk presented at TED Global 2012, Edinburgh, Scotland, June 2012.\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["Portrait of a Chemist\n"]], ["block_14", [" Lee Cronin \nWhat is it that chemists do? According to Lee Cronin (Figure 2.22), chemists make very complicated\nmolecules by \u201cchopping up\u201d small molecules and \u201creverse engineering\u201d them. He wonders if we could\n\u201cmake a really cool universal chemistry set\u201d by what he calls \u201capp-ing\u201d chemistry. Could we \u201capp\u201d\nchemistry?\n"]], ["block_15", ["In a 2012 TED talk, Lee describes one fascinating possibility: combining a collection of chemical \u201cinks\u201d\nwith a 3D printer capable of fabricating a reaction apparatus (tiny test tubes, beakers, and the like) to\nfashion a \u201cuniversal toolkit of chemistry.\u201d This toolkit could be used to create custom-tailored drugs to fight\na new superbug or to \u201cprint\u201d medicine personally configured to your genetic makeup, environment, and\nhealth situation. Says Cronin, \u201cWhat Apple did for music, I\u2019d like to do for the discovery and distribution of\nprescription drugs.\u201dView his full talk (http://openstax.org/l/16LeeCronin) at the TED website.\n"]], ["block_16", ["LINK TO LEARNING\n"]], ["block_17", ["EXAMPLE 2.6\n"]], ["block_18", [{"image_0": "95_0.png", "coords": [130, 57, 481, 205]}]]], "page_96": [["block_0", ["It is important to be aware that it may be possible for the same atoms to be arranged in different ways:\nCompounds with the same molecular formula may have different atom-to-atom bonding and therefore\ndifferent structures. For example, could there be another compound with the same formula as acetic acid,\nC2H4O2? And if so, what would be the structure of its molecules?\n"]], ["block_1", ["If you predict that another compound with the formula C2H4O2 could exist, then you demonstrated good\nchemical insight and are correct. Two C atoms, four H atoms, and two O atoms can also be arranged to form a\nmethyl formate, which is used in manufacturing, as an insecticide, and for quick-drying finishes. Methyl\nformate molecules have one of the oxygen atoms between the two carbon atoms, differing from the\narrangement in acetic acid molecules. Acetic acid and methyl formate are examples of isomers \u2014compounds\nwith the same chemical formula but different molecular structures (Figure 2.23). Note that this small\ndifference in the arrangement of the atoms has a major effect on their respective chemical properties. You\nwould certainly not want to use a solution of methyl formate as a substitute for a solution of acetic acid\n(vinegar) when you make salad dressing.\n"]], ["block_2", [" FIGURE 2.23 \nMolecules of (a) acetic acid and methyl formate (b) are structural isomers; they have the same\n"]], ["block_3", ["formula (C2H4O2) but different structures (and therefore different chemical properties).\n"]], ["block_4", ["Many types of isomers exist (Figure 2.24). Acetic acid and methyl formate are structural isomers , compounds\n"]], ["block_5", [" FIGURE 2.22 \nChemist Lee Cronin has been named one of the UK\u2019s 10 most inspirational scientists. The\n"]], ["block_6", ["youngest chair at the University of Glasgow, Lee runs a large research group, collaborates with many scientists\nworldwide, has published over 250 papers in top scientific journals, and has given more than 150 invited talks.\nHis research focuses on complex chemical systems and their potential to transform technology, but also\nbranches into nanoscience, solar fuels, synthetic biology, and even artificial life and evolution. (credit: image\ncourtesy of Lee Cronin)\n"]], ["block_7", [{"image_0": "96_0.png", "coords": [189, 57, 423, 283]}]], ["block_8", [{"image_1": "96_1.png", "coords": [189, 565, 423, 677]}]], ["block_9", [" 2.4 \u2022 Chemical Formulas \n 83 \n"]]], "page_97": [["block_0", [" 84 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", ["in which the molecules differ in how the atoms are connected to each other. There are also various types of\n spatial isomers , in which the relative orientations of the atoms in space can be different. For example, the\ncompound carvone (found in caraway seeds, spearmint, and mandarin orange peels) consists of two isomers\nthat are mirror images of each other. S-(+)-carvone smells like caraway, and R-(\u2212)-carvone smells like\nspearmint.\n"]], ["block_2", [{"image_0": "97_0.png", "coords": [72, 126, 540, 390]}]], ["block_3", [" FIGURE 2.24 \nMolecules of carvone are spatial isomers; they only differ in the relative orientations of the atoms in\n"]], ["block_4", ["space. (credit bottom left: modification of work by \u201cMiansari66\u201d/Wikimedia Commons; credit bottom right:\nmodification of work by Forest & Kim Starr)\n"]], ["block_5", ["Select this link (http://openstax.org/l/16isomers) to view an explanation of isomers, spatial isomers, and why\nthey have different smells (select the video titled \u201cMirror Molecule: Carvone\u201d).\n"]], ["block_6", [" 2.5 The Periodic Table \n"]], ["block_7", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_8", ["As early chemists worked to purify ores and discovered more elements, they realized that various elements\ncould be grouped together by their similar chemical behaviors. One such grouping includes lithium (Li),\nsodium (Na), and potassium (K): These elements all are shiny, conduct heat and electricity well, and have\nsimilar chemical properties. A second grouping includes calcium (Ca), strontium (Sr), and barium (Ba), which\nalso are shiny, good conductors of heat and electricity, and have chemical properties in common. However, the\nspecific properties of these two groupings are notably different from each other. For example: Li, Na, and K are\nmuch more reactive than are Ca, Sr, and Ba; Li, Na, and K form compounds with oxygen in a ratio of two of their\natoms to one oxygen atom, whereas Ca, Sr, and Ba form compounds with one of their atoms to one oxygen\natom. Fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) also exhibit similar properties to each other, but\nthese properties are drastically different from those of any of the elements above.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["\u2022\nState the periodic law and explain the organization of elements in the periodic table\n"]], ["block_11", ["\u2022\nPredict the general properties of elements based on their location within the periodic table\n"]], ["block_12", ["\u2022\nIdentify metals, nonmetals, and metalloids by their properties and/or location on the periodic table\n"]], ["block_13", ["LINK TO LEARNING\n"]]], "page_98": [["block_0", ["By the twentieth century, it became apparent that the periodic relationship involved atomic numbers rather\nthan atomic masses. The modern statement of this relationship, the periodic law , is as follows: the properties\nof the elements are periodic functions of their atomic numbers. A modern periodic table arranges the\nelements in increasing order of their atomic numbers and groups atoms with similar properties in the same\nvertical column (Figure 2.26). Each box represents an element and contains its atomic number, symbol,\naverage atomic mass, and (sometimes) name. The elements are arranged in seven horizontal rows, called\n periods or series , and 18 vertical columns, called groups . Groups are labeled at the top of each column. In the\nUnited States, the labels traditionally were numerals with capital letters. However, IUPAC recommends that the\nnumbers 1 through 18 be used, and these labels are more common. For the table to fit on a single page, parts of\ntwo of the rows, a total of 14 columns, are usually written below the main body of the table.\n"]], ["block_1", ["Dimitri Mendeleev in Russia (1869) and Lothar Meyer in Germany (1870) independently recognized that there\nwas a periodic relationship among the properties of the elements known at that time. Both published tables\nwith the elements arranged according to increasing atomic mass. But Mendeleev went one step further than\nMeyer: He used his table to predict the existence of elements that would have the properties similar to\naluminum and silicon, but were yet unknown. The discoveries of gallium (1875) and germanium (1886)\nprovided great support for Mendeleev\u2019s work. Although Mendeleev and Meyer had a long dispute over priority,\nMendeleev\u2019s contributions to the development of the periodic table are now more widely recognized (Figure\n2.25).\n"]], ["block_2", [{"image_0": "98_0.png", "coords": [72, 164, 540, 343]}]], ["block_3", [" FIGURE 2.25 \n(a) Dimitri Mendeleev is widely credited with creating (b) the first periodic table of the elements.\n"]], ["block_4", ["(credit a: modification of work by Serge Lachinov; credit b: modification of work by \u201cDen fj\u00e4ttrade ankan\u201d/Wikimedia\nCommons)\n"]], ["block_5", [" 2.5 \u2022 The Periodic Table \n 85 \n"]]], "page_99": [["block_0", [" 86 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", [{"image_0": "99_0.png", "coords": [72, 57, 540, 423]}]], ["block_2", ["Even after the periodic nature of elements and the table itself were widely accepted, gaps remained.\nMendeleev had predicted, and others including Henry Moseley had later confirmed, that there should be\nelements below Manganese in Group 7. German chemists Ida Tacke and Walter Noddack set out to find the\nelements, a quest being pursued by scientists around the world. Their method was unique in that they did not\nonly consider the properties of manganese, but also the elements horizontally adjacent to the missing\nelements 43 and 75 on the table. Thus, by investigating ores containing minerals of ruthenium (Ru), tungsten\n(W), osmium (Os), and so on, they were able to identify naturally occurring elements that helped complete the\ntable. Rhenium, one of their discoveries, was one of the last natural elements to be discovered and is the last\nstable element to be discovered. (Francium, the last natural element to be discovered, was identified by\nMarguerite Perey in 1939.)\n"]], ["block_3", ["Many elements differ dramatically in their chemical and physical properties, but some elements are similar in\ntheir behaviors. For example, many elements appear shiny, are malleable (able to be deformed without\nbreaking) and ductile (can be drawn into wires), and conduct heat and electricity well. Other elements are not\nshiny, malleable, or ductile, and are poor conductors of heat and electricity. We can sort the elements into large\nclasses with common properties: metals (elements that are shiny, malleable, good conductors of heat and\nelectricity\u2014shaded yellow); nonmetals (elements that appear dull, poor conductors of heat and\nelectricity\u2014shaded green); and metalloids (elements that conduct heat and electricity moderately well, and\npossess some properties of metals and some properties of nonmetals\u2014shaded purple).\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", [" FIGURE 2.26 \nElements in the periodic table are organized according to their properties.\n"]]], "page_100": [["block_0", ["The elements can also be classified into the main-group elements (or representative elements ) in the\ncolumns labeled 1, 2, and 13\u201318; the transition metals in the columns labeled 3\u201312; and inner transition \n metals in the two rows at the bottom of the table (the top-row elements are called lanthanides and the bottom-\nrow elements are actinides ; Figure 2.27). The elements can be subdivided further by more specific properties,\nsuch as the composition of the compounds they form. For example, the elements in group 1 (the first column)\nform compounds that consist of one atom of the element and one atom of hydrogen. These elements (except\nhydrogen) are known as alkali metals , and they all have similar chemical properties. The elements in group 2\n(the second column) form compounds consisting of one atom of the element and two atoms of hydrogen: These\nare called alkaline earth metals , with similar properties among members of that group. Other groups with\nspecific names are the pnictogens (group 15), chalcogens (group 16), halogens (group 17), and the noble \n gases (group 18, also known as inert gases ). The groups can also be referred to by the first element of the\ngroup: For example, the chalcogens can be called the oxygen group or oxygen family. Hydrogen is a unique,\nnonmetallic element with properties similar to both group 1 and group 17 elements. For that reason, hydrogen\nmay be shown at the top of both groups, or by itself.\n"]], ["block_1", [{"image_0": "100_0.png", "coords": [72, 240, 540, 516]}]], ["block_2", ["Click on this link (https://openstax.org/l/16Periodic) for an interactive periodic table, which you can use to\nexplore the properties of the elements (includes podcasts and videos of each element). You may also want to\ntry this one (https://openstax.org/l/16Periodic2) that shows photos of all the elements.\n"]], ["block_3", [" Naming Groups of Elements \n"]], ["block_4", ["Atoms of each of the following elements are essential for life. Give the group name for the following elements:\n"]], ["block_5", ["(a) chlorine\n"]], ["block_6", ["3 Per the IUPAC definition, group 12 elements are not transition metals, though they are often referred to as such. Additional details\non this group\u2019s elements are provided in a chapter on transition metals and coordination chemistry.\n"]], ["block_7", ["LINK TO LEARNING\n"]], ["block_8", ["EXAMPLE 2.7\n"]], ["block_9", [" FIGURE 2.27 \nThe periodic table organizes elements with similar properties into groups.\n"]], ["block_10", [" 2.5 \u2022 The Periodic Table \n 87 \n"]]], "page_101": [["block_0", [" 88 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", ["(b) calcium\n"]], ["block_2", ["(c) sodium\n"]], ["block_3", ["(d) sulfur\n"]], ["block_4", [" Solution \n"]], ["block_5", ["The family names are as follows:\n"]], ["block_6", ["(a) halogen\n"]], ["block_7", ["(b) alkaline earth metal\n"]], ["block_8", ["(c) alkali metal\n"]], ["block_9", ["(d) chalcogen\n"]], ["block_10", [" Check Your Learning \n"]], ["block_11", ["Give the group name for each of the following elements:\n"]], ["block_12", ["(a) krypton\n"]], ["block_13", ["(b) selenium\n"]], ["block_14", ["(c) barium\n"]], ["block_15", ["(d) lithium\n"]], ["block_16", [" Answer: \n(a) noble gas; (b) chalcogen; (c) alkaline earth metal; (d) alkali metal\n"]], ["block_17", ["As you will learn in your further study of chemistry, elements in groups often behave in a somewhat similar\nmanner. This is partly due to the number of electrons in their outer shell and their similar readiness to bond.\nThese shared properties can have far-ranging implications in nature, science, and medicine. For example,\nwhen Gertrude Elion and George Hitchens were investigating ways to interrupt cell and virus replication to\nfight diseases, they utilized the similarity between sulfur and oxygen (both in Group 16) and their capacity to\nbond in similar ways. Elion focused on purines, which are key components of DNA and which contain oxygen.\nShe found that by introducing sulfur-based compounds (called purine analogues) that mimic the structure of\npurines, molecules within DNA would bond to the analogues rather than the \"regular\" DNA purine. With the\nnormal DNA bonding and structure altered, Elion successfully interrupted cell replication. At its core, the\nstrategy worked because of the similarity between sulfur and oxygen. Her discovery led directly to important\ntreatments for leukemia. Overall, Elion's work with George Hitchens not only led to more treatments, but also\nchanged the entire methodology of drug development. By using specific elements and compounds to target\nspecific aspects of tumor cells, viruses, and bacteria, they laid the groundwork for many of today's most\ncommon and important medicines, used to help millions of people each year. They were awarded the Nobel\nPrize in 1988.\n"]], ["block_18", ["In studying the periodic table, you might have noticed something about the atomic masses of some of the\nelements. Element 43 (technetium), element 61 (promethium), and most of the elements with atomic number\n84 (polonium) and higher have their atomic mass given in square brackets. This is done for elements that\nconsist entirely of unstable, radioactive isotopes (you will learn more about radioactivity in the nuclear\nchemistry chapter). An average atomic weight cannot be determined for these elements because their\nradioisotopes may vary significantly in relative abundance, depending on the source, or may not even exist in\nnature. The number in square brackets is the atomic mass number (an approximate atomic mass) of the most\nstable isotope of that element.\n"]], ["block_19", [" Access for free at openstax.org \n"]]], "page_102": [["block_0", [" 2.6 Ionic and Molecular Compounds \n"]], ["block_1", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_2", ["In ordinary chemical reactions, the nucleus of each atom (and thus the identity of the element) remains\nunchanged. Electrons, however, can be added to atoms by transfer from other atoms, lost by transfer to other\natoms, or shared with other atoms. The transfer and sharing of electrons among atoms govern the chemistry of\nthe elements. During the formation of some compounds, atoms gain or lose electrons, and form electrically\ncharged particles called ions (Figure 2.28).\n"]], ["block_3", [{"image_0": "102_0.png", "coords": [72, 220, 540, 409]}]], ["block_4", [" FIGURE 2.28 \n(a) A sodium atom (Na) has equal numbers of protons and electrons (11) and is uncharged. (b) A\n"]], ["block_5", ["sodium cation (Na) has lost an electron, so it has one more proton (11) than electrons (10), giving it an overall\npositive charge, signified by a superscripted plus sign.\n"]], ["block_6", ["You can use the periodic table to predict whether an atom will form an anion or a cation, and you can often\npredict the charge of the resulting ion. Atoms of many main-group metals lose enough electrons to leave them\nwith the same number of electrons as an atom of the preceding noble gas. To illustrate, an atom of an alkali\nmetal (group 1) loses one electron and forms a cation with a 1+ charge; an alkaline earth metal (group 2) loses\ntwo electrons and forms a cation with a 2+ charge, and so on. For example, a neutral calcium atom, with 20\nprotons and 20 electrons, readily loses two electrons. This results in a cation with 20 protons, 18 electrons, and\na 2+ charge. It has the same number of electrons as atoms of the preceding noble gas, argon, and is symbolized\nCa. The name of a metal ion is the same as the name of the metal atom from which it forms, so Cais called\na calcium ion.\n"]], ["block_7", ["When atoms of nonmetal elements form ions, they generally gain enough electrons to give them the same\nnumber of electrons as an atom of the next noble gas in the periodic table. Atoms of group 17 gain one electron\nand form anions with a 1\u2212 charge; atoms of group 16 gain two electrons and form ions with a 2\u2212 charge, and so\non. For example, the neutral bromine atom, with 35 protons and 35 electrons, can gain one electron to provide\nit with 36 electrons. This results in an anion with 35 protons, 36 electrons, and a 1\u2212 charge. It has the same\nnumber of electrons as atoms of the next noble gas, krypton, and is symbolized Br. (A discussion of the theory\nsupporting the favored status of noble gas electron numbers reflected in these predictive rules for ion\nformation is provided in a later chapter of this text.)\n"]], ["block_8", ["Note the usefulness of the periodic table in predicting likely ion formation and charge (Figure 2.29). Moving\nfrom the far left to the right on the periodic table, main-group elements tend to form cations with a charge\nequal to the group number. That is, group 1 elements form 1+ ions; group 2 elements form 2+ ions, and so on.\nMoving from the far right to the left on the periodic table, elements often form anions with a negative charge\n"]], ["block_9", ["\u2022\nDefine ionic and molecular (covalent) compounds\n"]], ["block_10", ["\u2022\nPredict the type of compound formed from elements based on their location within the periodic table\n"]], ["block_11", ["\u2022\nDetermine formulas for simple ionic compounds\n"]], ["block_12", [" 2.6 \u2022 Ionic and Molecular Compounds \n 89 \n"]]], "page_103": [["block_0", [" 90 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", ["equal to the number of groups moved left from the noble gases. For example, group 17 elements (one group\nleft of the noble gases) form 1\u2212 ions; group 16 elements (two groups left) form 2\u2212 ions, and so on. This trend\ncan be used as a guide in many cases, but its predictive value decreases when moving toward the center of the\nperiodic table. In fact, transition metals and some other metals often exhibit variable charges that are not\npredictable by their location in the table. For example, copper can form ions with a 1+ or 2+ charge, and iron\ncan form ions with a 2+ or 3+ charge.\n"]], ["block_2", [{"image_0": "103_0.png", "coords": [72, 139, 540, 424]}]], ["block_3", [" Composition of Ions \n"]], ["block_4", ["An ion found in some compounds used as antiperspirants contains 13 protons and 10 electrons. What is its\nsymbol?\n"]], ["block_5", [" Solution \n"]], ["block_6", ["Because the number of protons remains unchanged when an atom forms an ion, the atomic number of the\nelement must be 13. Knowing this lets us use the periodic table to identify the element as Al (aluminum). The\nAl atom has lost three electrons and thus has three more positive charges (13) than it has electrons (10). This is\nthe aluminum cation, Al.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["Give the symbol and name for the ion with 34 protons and 36 electrons.\n"]], ["block_9", [" Answer: \nSe, the selenide ion\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["EXAMPLE 2.8\n"]], ["block_12", [" FIGURE 2.29 \nSome elements exhibit a regular pattern of ionic charge when they form ions.\n"]]], "page_104": [["block_0", [" Formation of Ions \n"]], ["block_1", ["Magnesium and nitrogen react to form an ionic compound. Predict which forms an anion, which forms a\ncation, and the charges of each ion. Write the symbol for each ion and name them.\n"]], ["block_2", [" Solution \n"]], ["block_3", ["Magnesium\u2019s position in the periodic table (group 2) tells us that it is a metal. Metals form positive ions\n(cations). A magnesium atom must lose two electrons to have the same number electrons as an atom of the\nprevious noble gas, neon. Thus, a magnesium atom will form a cation with two fewer electrons than protons\nand a charge of 2+. The symbol for the ion is Mg, and it is called a magnesium ion.\n"]], ["block_4", ["Nitrogen\u2019s position in the periodic table (group 15) reveals that it is a nonmetal. Nonmetals form negative ions\n(anions). A nitrogen atom must gain three electrons to have the same number of electrons as an atom of the\nfollowing noble gas, neon. Thus, a nitrogen atom will form an anion with three more electrons than protons\nand a charge of 3\u2212. The symbol for the ion is N, and it is called a nitride ion.\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["Aluminum and carbon react to form an ionic compound. Predict which forms an anion, which forms a cation,\nand the charges of each ion. Write the symbol for each ion and name them.\n"]], ["block_7", [" Answer: \nAl will form a cation with a charge of 3+: Al, an aluminum ion. Carbon will form an anion with a charge of 4\u2212:\nC, a carbide ion.\n"]], ["block_8", ["The ions that we have discussed so far are called monatomic ions , that is, they are ions formed from only one\natom. We also find many polyatomic ions . These ions, which act as discrete units, are electrically charged\nmolecules (a group of bonded atoms with an overall charge). Some of the more important polyatomic ions are\nlisted in Table 2.5. Oxyanions are polyatomic ions that contain one or more oxygen atoms. At this point in your\nstudy of chemistry, you should memorize the names, formulas, and charges of the most common polyatomic\nions. Because you will use them repeatedly, they will soon become familiar.\n"]], ["block_9", ["EXAMPLE 2.9\n"]], ["block_10", [" TABLE 2.5 \n"]], ["block_11", [" Name \n Formula \n Related Acid \n Formula \n"]], ["block_12", ["ammonium\n"]], ["block_13", ["hydronium\n"]], ["block_14", ["peroxide\n"]], ["block_15", ["hydroxide\n"]], ["block_16", ["acetate\nacetic acid\nCH3COOH\n"]], ["block_17", ["cyanide\nCN\nhydrocyanic acid\nHCN\n"]], ["block_18", ["azide\nhydrazoic acid\nHN3\n"]], ["block_19", ["carbonate\ncarbonic acid\nH2CO3\n"]], ["block_20", ["Common Polyatomic Ions\n"]], ["block_21", [" 2.6 \u2022 Ionic and Molecular Compounds \n 91 \n"]]], "page_105": [["block_0", [" 92 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", ["Note that there is a system for naming some polyatomic ions; -ate and -ite are suffixes designating polyatomic\nions containing more or fewer oxygen atoms. Per- (short for \u201chyper\u201d) and hypo- (meaning \u201cunder\u201d) are\nprefixes meaning more oxygen atoms than -ate and fewer oxygen atoms than -ite, respectively. For example,\nperchlorate is\nchlorate is\nchlorite is\nand hypochlorite is ClO. Unfortunately, the\n"]], ["block_2", ["number of oxygen atoms corresponding to a given suffix or prefix is not consistent; for example, nitrate is\n"]], ["block_3", ["The nature of the attractive forces that hold atoms or ions together within a compound is the basis for\nclassifying chemical bonding. When electrons are transferred and ions form, ionic bonds result. Ionic bonds\nare electrostatic forces of attraction, that is, the attractive forces experienced between objects of opposite\nelectrical charge (in this case, cations and anions). When electrons are \u201cshared\u201d and molecules form, covalent \n bonds result. Covalent bonds are the attractive forces between the positively charged nuclei of the bonded\natoms and one or more pairs of electrons that are located between the atoms. Compounds are classified as\nionic or molecular (covalent) on the basis of the bonds present in them.\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", ["while sulfate is\nThis will be covered in more detail in the next module on nomenclature.\n"]], ["block_6", [" TABLE 2.5 \n"]], ["block_7", [" Name \n Formula \n Related Acid \n Formula \n"]], ["block_8", ["bicarbonate\n"]], ["block_9", ["nitrate\nnitric acid\nHNO3\n"]], ["block_10", ["nitrite\nnitrous acid\nHNO2\n"]], ["block_11", ["sulfate\nsulfuric acid\nH2SO4\n"]], ["block_12", ["hydrogen sulfate\n"]], ["block_13", ["sulfite\nsulfurous acid\nH2SO3\n"]], ["block_14", ["hydrogen sulfite\n"]], ["block_15", ["phosphate\nphosphoric acid\nH3PO4\n"]], ["block_16", ["hydrogen phosphate\n"]], ["block_17", ["dihydrogen phosphate\n"]], ["block_18", ["perchlorate\nperchloric acid\nHClO4\n"]], ["block_19", ["chlorate\nchloric acid\nHClO3\n"]], ["block_20", ["chlorite\nchlorous acid\nHClO2\n"]], ["block_21", ["hypochlorite\nClO\nhypochlorous acid\nHClO\n"]], ["block_22", ["chromate\nchromic acid\nH2CrO4\n"]], ["block_23", ["dichromate\ndichromic acid\nH2Cr2O7\n"]], ["block_24", ["permanganate\npermanganic acid\nHMnO4\n"]]], "page_106": [["block_0", [" Ionic Compounds \n"]], ["block_1", ["When an element composed of atoms that readily lose electrons (a metal) reacts with an element composed of\natoms that readily gain electrons (a nonmetal), a transfer of electrons usually occurs, producing ions. The\ncompound formed by this transfer is stabilized by the electrostatic attractions (ionic bonds) between the ions\nof opposite charge present in the compound. For example, when each sodium atom in a sample of sodium\nmetal (group 1) gives up one electron to form a sodium cation, Na, and each chlorine atom in a sample of\nchlorine gas (group 17) accepts one electron to form a chloride anion, Cl, the resulting compound, NaCl, is\ncomposed of sodium ions and chloride ions in the ratio of one Naion for each Clion. Similarly, each calcium\natom (group 2) can give up two electrons and transfer one to each of two chlorine atoms to form CaCl2, which is\ncomposed of Caand Clions in the ratio of one Caion to two Clions.\n"]], ["block_2", ["A compound that contains ions and is held together by ionic bonds is called an ionic compound . The periodic\ntable can help us recognize many of the compounds that are ionic: When a metal is combined with one or more\nnonmetals, the compound is usually ionic. This guideline works well for predicting ionic compound formation\nfor most of the compounds typically encountered in an introductory chemistry course. However, it is not\nalways true (for example, aluminum chloride, AlCl3, is not ionic).\n"]], ["block_3", ["You can often recognize ionic compounds because of their properties. Ionic compounds are solids that\ntypically melt at high temperatures and boil at even higher temperatures. For example, sodium chloride melts\nat 801 \u00b0C and boils at 1413 \u00b0C. (As a comparison, the molecular compound water melts at 0 \u00b0C and boils at 100\n\u00b0C.) In solid form, an ionic compound is not electrically conductive because its ions are unable to flow\n(\u201celectricity\u201d is the flow of charged particles). When molten, however, it can conduct electricity because its ions\nare able to move freely through the liquid (Figure 2.30).\n"]], ["block_4", [" FIGURE 2.30 \nSodium chloride melts at 801 \u00b0C and conducts electricity when molten. (credit: modification of work\n"]], ["block_5", ["by Mark Blaser and Matt Evans)\n"]], ["block_6", ["Watch this video (http://openstax.org/l/16moltensalt) to see a mixture of salts melt and conduct electricity.\n"]], ["block_7", ["In every ionic compound, the total number of positive charges of the cations equals the total number of\nnegative charges of the anions. Thus, ionic compounds are electrically neutral overall, even though they\ncontain positive and negative ions. We can use this observation to help us write the formula of an ionic\ncompound. The formula of an ionic compound must have a ratio of ions such that the numbers of positive and\nnegative charges are equal.\n"]], ["block_8", [" Predicting the Formula of an Ionic Compound \n"]], ["block_9", ["The gemstone sapphire (Figure 2.31) is mostly a compound of aluminum and oxygen that contains aluminum\n"]], ["block_10", ["LINK TO LEARNING\n"]], ["block_11", ["EXAMPLE 2.10\n"]], ["block_12", [{"image_0": "106_0.png", "coords": [130, 348, 481, 496]}]], ["block_13", [" 2.6 \u2022 Ionic and Molecular Compounds \n 93 \n"]]], "page_107": [["block_0", [" 94 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", ["cations, Al, and oxygen anions, O. What is the formula of this compound?\n"]], ["block_2", [" FIGURE 2.31 \nAlthough pure aluminum oxide is colorless, trace amounts of iron and titanium give blue sapphire its\n"]], ["block_3", ["characteristic color. (credit: modification of work by Stanislav Doronenko)\n"]], ["block_4", [" Solution \n"]], ["block_5", ["Because the ionic compound must be electrically neutral, it must have the same number of positive and\nnegative charges. Two aluminum ions, each with a charge of 3+, would give us six positive charges, and three\noxide ions, each with a charge of 2\u2212, would give us six negative charges. The formula would be Al2O3.\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["Predict the formula of the ionic compound formed between the sodium cation, Na, and the sulfide anion, S.\n"]], ["block_8", [" Answer: \nNa2S\n"]], ["block_9", ["Many ionic compounds contain polyatomic ions (Table 2.5) as the cation, the anion, or both. As with simple\nionic compounds, these compounds must also be electrically neutral, so their formulas can be predicted by\ntreating the polyatomic ions as discrete units. We use parentheses in a formula to indicate a group of atoms\nthat behave as a unit. For example, the formula for calcium phosphate, one of the minerals in our bones, is\nCa3(PO4)2. This formula indicates that there are three calcium ions (Ca) for every two phosphate\ngroups. The\ngroups are discrete units, each consisting of one phosphorus atom and four oxygen atoms,\n"]], ["block_10", ["and having an overall charge of 3\u2212. The compound is electrically neutral, and its formula shows a total count of\nthree Ca, two P, and eight O atoms.\n"]], ["block_11", [" Predicting the Formula of a Compound with a Polyatomic Anion \n"]], ["block_12", ["Baking powder contains calcium dihydrogen phosphate, an ionic compound composed of the ions Caand\n"]], ["block_13", [" Solution \n"]], ["block_14", ["The positive and negative charges must balance, and this ionic compound must be electrically neutral. Thus,\nwe must have two negative charges to balance the 2+ charge of the calcium ion. This requires a ratio of one\nCaion to two\nions. We designate this by enclosing the formula for the dihydrogen phosphate ion in\n"]], ["block_15", ["parentheses and adding a subscript 2. The formula is Ca(H2PO4)2.\n"]], ["block_16", [" Check Your Learning \n"]], ["block_17", ["Predict the formula of the ionic compound formed between the lithium ion and the peroxide ion,\n(Hint:\n"]], ["block_18", ["Use the periodic table to predict the sign and the charge on the lithium ion.)\n"]], ["block_19", [" Answer: \nLi2O2\n"]], ["block_20", ["Because an ionic compound is not made up of single, discrete molecules, it may not be properly symbolized\nusing a molecular formula. Instead, ionic compounds must be symbolized by a formula indicating the relative\n"]], ["block_21", [" Access for free at openstax.org \n"]], ["block_22", ["EXAMPLE 2.11\n"]], ["block_23", ["What is the formula of this compound?\n"]], ["block_24", [{"image_0": "107_0.png", "coords": [247, 76, 364, 165]}]]], "page_108": [["block_0", ["numbers of its constituent ions. For compounds containing only monatomic ions (such as NaCl) and for many\ncompounds containing polyatomic ions (such as CaSO4), these formulas are just the empirical formulas\nintroduced earlier in this chapter. However, the formulas for some ionic compounds containing polyatomic\nions are not empirical formulas. For example, the ionic compound sodium oxalate is comprised of Naand\n"]], ["block_1", ["not the smallest-possible whole numbers, as each can be divided by 2 to yield the empirical formula, NaCO2.\nThis is not the accepted formula for sodium oxalate, however, as it does not accurately represent the\ncompound\u2019s polyatomic anion,\n"]], ["block_2", [" Molecular Compounds \n"]], ["block_3", ["Many compounds do not contain ions but instead consist solely of discrete, neutral molecules. These\n molecular compounds (covalent compounds) result when atoms share, rather than transfer (gain or lose),\nelectrons. Covalent bonding is an important and extensive concept in chemistry, and it will be treated in\nconsiderable detail in a later chapter of this text. We can often identify molecular compounds on the basis of\ntheir physical properties. Under normal conditions, molecular compounds often exist as gases, low-boiling\nliquids, and low-melting solids, although many important exceptions exist.\n"]], ["block_4", ["Whereas ionic compounds are usually formed when a metal and a nonmetal combine, covalent compounds\nare usually formed by a combination of nonmetals. Thus, the periodic table can help us recognize many of the\ncompounds that are covalent. While we can use the positions of a compound\u2019s elements in the periodic table to\npredict whether it is ionic or covalent at this point in our study of chemistry, you should be aware that this is a\nvery simplistic approach that does not account for a number of interesting exceptions. Shades of gray exist\nbetween ionic and molecular compounds, and you\u2019ll learn more about those later.\n"]], ["block_5", [" Predicting the Type of Bonding in Compounds \n"]], ["block_6", ["Predict whether the following compounds are ionic or molecular:\n"]], ["block_7", ["(a) KI, the compound used as a source of iodine in table salt\n"]], ["block_8", ["(b) H2O2, the bleach and disinfectant hydrogen peroxide\n"]], ["block_9", ["(c) CHCl3, the anesthetic chloroform\n"]], ["block_10", ["(d) Li2CO3, a source of lithium in antidepressants\n"]], ["block_11", [" Solution \n"]], ["block_12", ["(a) Potassium (group 1) is a metal, and iodine (group 17) is a nonmetal; KI is predicted to be ionic.\n"]], ["block_13", ["(b) Hydrogen (group 1) is a nonmetal, and oxygen (group 16) is a nonmetal; H2O2 is predicted to be molecular.\n"]], ["block_14", ["(c) Carbon (group 14) is a nonmetal, hydrogen (group 1) is a nonmetal, and chlorine (group 17) is a nonmetal;\nCHCl3 is predicted to be molecular.\n"]], ["block_15", ["(d) Lithium (group 1) is a metal, and carbonate is a polyatomic ion; Li2CO3 is predicted to be ionic.\n"]], ["block_16", [" Check Your Learning \n"]], ["block_17", ["Using the periodic table, predict whether the following compounds are ionic or covalent:\n"]], ["block_18", ["(a) SO2\n"]], ["block_19", ["(b) CaF2\n"]], ["block_20", ["(c) N2H4\n"]], ["block_21", ["(d) Al2(SO4)3\n"]], ["block_22", ["EXAMPLE 2.12\n"]], ["block_23", ["ions combined in a 2:1 ratio, and its formula is written as Na2C2O4. The subscripts in this formula are\n"]], ["block_24", [" 2.6 \u2022 Ionic and Molecular Compounds \n 95 \n"]]], "page_109": [["block_0", [" 96 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", [" Answer: \n(a) molecular; (b) ionic; (c) molecular; (d) ionic\n"]], ["block_2", [" 2.7 Chemical Nomenclature \n"]], ["block_3", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_4", [" Nomenclature , a collection of rules for naming things, is important in science and in many other situations.\nThis module describes an approach that is used to name simple ionic and molecular compounds, such as\nNaCl, CaCO3, and N2O4. The simplest of these are binary compounds , those containing only two elements, but\nwe will also consider how to name ionic compounds containing polyatomic ions, and one specific, very\nimportant class of compounds known as acids (subsequent chapters in this text will focus on these compounds\nin great detail). We will limit our attention here to inorganic compounds, compounds that are composed\nprincipally of elements other than carbon, and will follow the nomenclature guidelines proposed by IUPAC.\nThe rules for organic compounds, in which carbon is the principle element, will be treated in a later chapter on\norganic chemistry.\n"]], ["block_5", [" Ionic Compounds \n"]], ["block_6", ["To name an inorganic compound, we need to consider the answers to several questions. First, is the compound\nionic or molecular? If the compound is ionic, does the metal form ions of only one type (fixed charge) or more\nthan one type (variable charge)? Are the ions monatomic or polyatomic? If the compound is molecular, does it\ncontain hydrogen? If so, does it also contain oxygen? From the answers we derive, we place the compound in\nan appropriate category and then name it accordingly.\n"]], ["block_7", [" Compounds Containing Only Monatomic Ions \n"]], ["block_8", ["The name of a binary compound containing monatomic ions consists of the name of the cation (the name of\nthe metal) followed by the name of the anion (the name of the nonmetallic element with its ending replaced by\nthe suffix \u2013ide). Some examples are given in Table 2.6.\n"]], ["block_9", [" Compounds Containing Polyatomic Ions \n"]], ["block_10", ["Compounds containing polyatomic ions are named similarly to those containing only monatomic ions, i.e. by\nnaming first the cation and then the anion. Examples are shown in Table 2.7.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["\u2022\nDerive names for common types of inorganic compounds using a systematic approach\n"]], ["block_13", [" TABLE 2.6 \n"]], ["block_14", ["NaCl, sodium chloride\nNa2O, sodium oxide\n"]], ["block_15", ["KBr, potassium bromide\nCdS, cadmium sulfide\n"]], ["block_16", ["CaI2, calcium iodide\nMg3N2, magnesium nitride\n"]], ["block_17", ["CsF, cesium fluoride\nCa3P2, calcium phosphide\n"]], ["block_18", ["LiCl, lithium chloride\nAl4C3, aluminum carbide\n"]], ["block_19", ["Names of Some Ionic Compounds\n"]]], "page_110": [["block_0", ["Chemistry in Everyday Life\n"]], ["block_1", [" Ionic Compounds in Your Cabinets \nEvery day you encounter and use a large number of ionic compounds. Some of these compounds, where\nthey are found, and what they are used for are listed in Table 2.8. Look at the label or ingredients list on the\nvarious products that you use during the next few days, and see if you run into any of those in this table, or\nfind other ionic compounds that you could now name or write as a formula.\n"]], ["block_2", [" TABLE 2.8 \n"]], ["block_3", [" Ionic Compound \n Use \n"]], ["block_4", ["NaCl, sodium chloride\nordinary table salt\n"]], ["block_5", ["KI, potassium iodide\nadded to \u201ciodized\u201d salt for thyroid health\n"]], ["block_6", ["NaF, sodium fluoride\ningredient in toothpaste\n"]], ["block_7", ["NaHCO3, sodium bicarbonate\nbaking soda; used in cooking (and as antacid)\n"]], ["block_8", ["Na2CO3, sodium carbonate\nwashing soda; used in cleaning agents\n"]], ["block_9", ["NaOCl, sodium hypochlorite\nactive ingredient in household bleach\n"]], ["block_10", ["CaCO3 calcium carbonate\ningredient in antacids\n"]], ["block_11", ["Mg(OH)2, magnesium hydroxide\ningredient in antacids\n"]], ["block_12", ["Al(OH)3, aluminum hydroxide\ningredient in antacids\n"]], ["block_13", ["NaOH, sodium hydroxide\nlye; used as drain cleaner\n"]], ["block_14", ["K3PO4, potassium phosphate\nfood additive (many purposes)\n"]], ["block_15", ["MgSO4, magnesium sulfate\nadded to purified water\n"]], ["block_16", ["Na2HPO4, sodium hydrogen phosphate\nanti-caking agent; used in powdered products\n"]], ["block_17", [" TABLE 2.7 \n"]], ["block_18", ["KC2H3O2, potassium acetate\nNH4Cl, ammonium chloride\n"]], ["block_19", ["NaHCO3, sodium bicarbonate\nCaSO4, calcium sulfate\n"]], ["block_20", ["Al2(CO3)3, aluminum carbonate\nMg3(PO4)2, magnesium phosphate\n"]], ["block_21", ["Names of Some Polyatomic Ionic Compounds\n"]], ["block_22", ["Everyday Ionic Compounds\n"]], ["block_23", [" 2.7 \u2022 Chemical Nomenclature \n 97 \n"]]], "page_111": [["block_0", [" 98 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", ["Out-of-date nomenclature used the suffixes \u2013ic and \u2013ous to designate metals with higher and lower charges,\nrespectively: Iron(III) chloride, FeCl3, was previously called ferric chloride, and iron(II) chloride, FeCl2, was\nknown as ferrous chloride. Though this naming convention has been largely abandoned by the scientific\ncommunity, it remains in use by some segments of industry. For example, you may see the words stannous\nfluoride on a tube of toothpaste. This represents the formula SnF2, which is more properly named tin(II)\nfluoride. The other fluoride of tin is SnF4, which was previously called stannic fluoride but is now named\ntin(IV) fluoride.\n"]], ["block_2", [" Compounds Containing a Metal Ion with a Variable Charge \n"]], ["block_3", ["Most of the transition metals and some main group metals can form two or more cations with different\ncharges. Compounds of these metals with nonmetals are named with the same method as compounds in the\nfirst category, except the charge of the metal ion is specified by a Roman numeral in parentheses after the\nname of the metal. The charge of the metal ion is determined from the formula of the compound and the\ncharge of the anion. For example, consider binary ionic compounds of iron and chlorine. Iron typically exhibits\na charge of either 2+ or 3+ (see Figure 2.29), and the two corresponding compound formulas are FeCl2 and\nFeCl3. The simplest name, \u201ciron chloride,\u201d will, in this case, be ambiguous, as it does not distinguish between\nthese two compounds. In cases like this, the charge of the metal ion is included as a Roman numeral in\nparentheses immediately following the metal name. These two compounds are then unambiguously named\niron(II) chloride and iron(III) chloride, respectively. Other examples are provided in Table 2.9.\n"]], ["block_4", [" Ionic Hydrates \n"]], ["block_5", ["Ionic compounds that contain water molecules as integral components of their crystals are called hydrates .\nThe name for an ionic hydrate is derived by adding a term to the name for the anhydrous (meaning \u201cnot\nhydrated\u201d) compound that indicates the number of water molecules associated with each formula unit of the\ncompound. The added word begins with a Greek prefix denoting the number of water molecules (see Table\n2.10) and ends with \u201chydrate.\u201d For example, the anhydrous compound copper(II) sulfate also exists as a\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [" TABLE 2.8 \n"]], ["block_8", [" Ionic Compound \n Use \n"]], ["block_9", ["Na2SO3, sodium sulfite\npreservative\n"]], ["block_10", [" TABLE 2.9 \n"]], ["block_11", ["Some Ionic Compounds with Variably Charged Metal Ions\n"]], ["block_12", [" Compound \n Name \n"]], ["block_13", ["FeCl2\niron(II) chloride\n"]], ["block_14", ["FeCl3\niron(III) chloride\n"]], ["block_15", ["Hg2O\nmercury(I) oxide\n"]], ["block_16", ["HgO\nmercury(II) oxide\n"]], ["block_17", ["SnF2\ntin(II) fluoride\n"]], ["block_18", ["SnF4\ntin(IV) fluoride\n"]]], "page_112": [["block_0", ["hydrate containing five water molecules and named copper(II) sulfate pentahydrate. Washing soda is the\ncommon name for a hydrate of sodium carbonate containing 10 water molecules; the systematic name is\nsodium carbonate decahydrate.\n"]], ["block_1", ["Formulas for ionic hydrates are written by appending a vertically centered dot, a coefficient representing the\nnumber of water molecules, and the formula for water. The two examples mentioned in the previous paragraph\nare represented by the formulas\n"]], ["block_2", [" Naming Ionic Compounds \n"]], ["block_3", ["Name the following ionic compounds\n"]], ["block_4", ["(a) Fe2S3\n"]], ["block_5", ["(b) CuSe\n"]], ["block_6", ["(c) GaN\n"]], ["block_7", ["(d) MgSO4\u00b77H2O\n"]], ["block_8", ["(e) Ti2(SO4)3\n"]], ["block_9", [" Solution \n"]], ["block_10", ["The anions in these compounds have a fixed negative charge (S, Se, N, and\nand the compounds\n"]], ["block_11", ["must be neutral. Because the total number of positive charges in each compound must equal the total number\nof negative charges, the positive ions must be Fe, Cu, Ga, Mg, and Ti. These charges are used in the\nnames of the metal ions:\n"]], ["block_12", ["(a) iron(III) sulfide\n"]], ["block_13", ["(b) copper(II) selenide\n"]], ["block_14", ["(c) gallium(III) nitride\n"]], ["block_15", ["(d) magnesium sulfate heptahydrate\n"]], ["block_16", ["(e) titanium(III) sulfate\n"]], ["block_17", ["EXAMPLE 2.13\n"]], ["block_18", [" TABLE 2.10 \n"]], ["block_19", [" Number \n Prefix \n Number \n Prefix \n"]], ["block_20", ["1 (sometimes omitted)\nmono-\n6\nhexa-\n"]], ["block_21", ["2\ndi-\n7\nhepta-\n"]], ["block_22", ["3\ntri-\n8\nocta-\n"]], ["block_23", ["4\ntetra-\n9\nnona-\n"]], ["block_24", ["5\npenta-\n10\ndeca-\n"]], ["block_25", ["Nomenclature Prefixes\n"]], ["block_26", [" 2.7 \u2022 Chemical Nomenclature \n 99 \n"]]], "page_113": [["block_0", [" 100 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["Write the formulas of the following ionic compounds:\n"]], ["block_3", ["(a) chromium(III) phosphide\n"]], ["block_4", ["(b) mercury(II) sulfide\n"]], ["block_5", ["(c) manganese(II) phosphate\n"]], ["block_6", ["(d) copper(I) oxide\n"]], ["block_7", ["(e) iron(III) chloride dihydrate\n"]], ["block_8", [" Answer: \n(a) CrP; (b) HgS; (c) Mn3(PO4)2; (d) Cu2O; (e) FeCl3\u00b72H2O\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["Chemistry in Everyday Life\n"]], ["block_11", [" Erin Brockovich and Chromium Contamination \nIn the early 1990s, legal file clerk Erin Brockovich (Figure 2.32) discovered a high rate of serious illnesses\nin the small town of Hinckley, California. Her investigation eventually linked the illnesses to groundwater\ncontaminated by Cr(VI) used by Pacific Gas & Electric (PG&E) to fight corrosion in a nearby natural gas\npipeline. As dramatized in the film Erin Brockovich (for which Julia Roberts won an Oscar), Erin and lawyer\nEdward Masry sued PG&E for contaminating the water near Hinckley in 1993. The settlement they won in\n1996\u2014$333 million\u2014was the largest amount ever awarded for a direct-action lawsuit in the US at that time.\n"]], ["block_12", [" FIGURE 2.32 \n(a) Erin Brockovich found that Cr(VI), used by PG&E, had contaminated the Hinckley, California,\n"]], ["block_13", ["water supply. (b) The Cr(VI) ion is often present in water as the polyatomic ions chromate,\n(left), and\n"]], ["block_14", ["dichromate,\n(right).\n"]], ["block_15", ["Chromium compounds are widely used in industry, such as for chrome plating, in dye-making, as\npreservatives, and to prevent corrosion in cooling tower water, as occurred near Hinckley. In the\nenvironment, chromium exists primarily in either the Cr(III) or Cr(VI) forms. Cr(III), an ingredient of many\nvitamin and nutritional supplements, forms compounds that are not very soluble in water, and it has low\ntoxicity. But Cr(VI) is much more toxic and forms compounds that are reasonably soluble in water.\nExposure to small amounts of Cr(VI) can lead to damage of the respiratory, gastrointestinal, and immune\nsystems, as well as the kidneys, liver, blood, and skin.\n"]], ["block_16", ["Despite cleanup efforts, Cr(VI) groundwater contamination remains a problem in Hinckley and other\nlocations across the globe. A 2010 study by the Environmental Working Group found that of 35 US cities\ntested, 31 had higher levels of Cr(VI) in their tap water than the public health goal of 0.02 parts per billion\nset by the California Environmental Protection Agency.\n"]], ["block_17", [{"image_0": "113_0.png", "coords": [90, 357, 522, 518]}]]], "page_114": [["block_0", [" Molecular (Covalent) Compounds \n"]], ["block_1", ["The bonding characteristics of inorganic molecular compounds are different from ionic compounds, and they\nare named using a different system as well. The charges of cations and anions dictate their ratios in ionic\ncompounds, so specifying the names of the ions provides sufficient information to determine chemical\nformulas. However, because covalent bonding allows for significant variation in the combination ratios of the\natoms in a molecule, the names for molecular compounds must explicitly identify these ratios.\n"]], ["block_2", [" Compounds Composed of Two Elements \n"]], ["block_3", ["When two nonmetallic elements form a molecular compound, several combination ratios are often possible.\nFor example, carbon and oxygen can form the compounds CO and CO2. Since these are different substances\nwith different properties, they cannot both have the same name (they cannot both be called carbon oxide). To\ndeal with this situation, we use a naming method that is somewhat similar to that used for ionic compounds,\nbut with added prefixes to specify the numbers of atoms of each element. The name of the more metallic\nelement (the one farther to the left and/or bottom of the periodic table) is first, followed by the name of the\nmore nonmetallic element (the one farther to the right and/or top) with its ending changed to the suffix \u2013ide.\nThe numbers of atoms of each element are designated by the Greek prefixes shown in Table 2.10.\n"]], ["block_4", ["When only one atom of the first element is present, the prefix mono- is usually deleted from that part. Thus, CO\nis named carbon monoxide, and CO2 is called carbon dioxide. When two vowels are adjacent, the a in the Greek\nprefix is usually dropped. Some other examples are shown in Table 2.11.\n"]], ["block_5", ["There are a few common names that you will encounter as you continue your study of chemistry. For example,\nalthough NO is often called nitric oxide, its proper name is nitrogen monoxide. Similarly, N2O is known as\nnitrous oxide even though our rules would specify the name dinitrogen monoxide. (And H2O is usually called\nwater, not dihydrogen monoxide.) You should commit to memory the common names of compounds as you\nencounter them.\n"]], ["block_6", [" Naming Covalent Compounds \n"]], ["block_7", ["Name the following covalent compounds:\n"]], ["block_8", ["(a) SF6\n"]], ["block_9", ["(b) N2O3\n"]], ["block_10", ["(c) Cl2O7\n"]], ["block_11", ["EXAMPLE 2.14\n"]], ["block_12", [" TABLE 2.11 \n"]], ["block_13", [" Compound \n Name \n Compound \n Name \n"]], ["block_14", ["SO2\nsulfur dioxide\nBCl3\nboron trichloride\n"]], ["block_15", ["SO3\nsulfur trioxide\nSF6\nsulfur hexafluoride\n"]], ["block_16", ["NO2\nnitrogen dioxide\nPF5\nphosphorus pentafluoride\n"]], ["block_17", ["N2O4\ndinitrogen tetroxide\nP4O10\ntetraphosphorus decaoxide\n"]], ["block_18", ["N2O5\ndinitrogen pentoxide\nIF7\niodine heptafluoride\n"]], ["block_19", ["Names of Some Molecular Compounds Composed of Two Elements\n"]], ["block_20", [" 2.7 \u2022 Chemical Nomenclature \n 101 \n"]]], "page_115": [["block_0", [" 102 \n 2 \u2022 Atoms, Molecules, and Ions \n"]], ["block_1", ["For example, when the gas HCl (hydrogen chloride) is dissolved in water, the solution is called hydrochloric\nacid. Several other examples of this nomenclature are shown in Table 2.12.\n"]], ["block_2", ["(d) P4O6\n"]], ["block_3", [" Solution \n"]], ["block_4", ["Because these compounds consist solely of nonmetals, we use prefixes to designate the number of atoms of\neach element:\n"]], ["block_5", ["(a) sulfur hexafluoride\n"]], ["block_6", ["(b) dinitrogen trioxide\n"]], ["block_7", ["(c) dichlorine heptoxide\n"]], ["block_8", ["(d) tetraphosphorus hexoxide\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["Write the formulas for the following compounds:\n"]], ["block_11", ["(a) phosphorus pentachloride\n"]], ["block_12", ["(b) dinitrogen monoxide\n"]], ["block_13", ["(c) iodine heptafluoride\n"]], ["block_14", ["(d) carbon tetrachloride\n"]], ["block_15", [" Answer: \n(a) PCl5; (b) N2O; (c) IF7; (d) CCl4\n"]], ["block_16", ["The following website (http://openstax.org/l/16chemcompname) provides practice with naming chemical\ncompounds and writing chemical formulas. You can choose binary, polyatomic, and variable charge ionic\ncompounds, as well as molecular compounds.\n"]], ["block_17", [" Binary Acids \n"]], ["block_18", ["Some compounds containing hydrogen are members of an important class of substances known as acids. The\nchemistry of these compounds is explored in more detail in later chapters of this text, but for now, it will\nsuffice to note that many acids release hydrogen ions, H, when dissolved in water. To denote this distinct\nchemical property, a mixture of water with an acid is given a name derived from the compound\u2019s name. If the\ncompound is a binary acid (comprised of hydrogen and one other nonmetallic element):\n"]], ["block_19", [" Access for free at openstax.org \n"]], ["block_20", ["1.\nThe word \u201chydrogen\u201d is changed to the prefix hydro-\n"]], ["block_21", ["2.\nThe other nonmetallic element name is modified by adding the suffix -ic\n"]], ["block_22", ["3.\nThe word \u201cacid\u201d is added as a second word\n"]], ["block_23", ["LINK TO LEARNING\n"]], ["block_24", [" TABLE 2.12 \n"]], ["block_25", [" Name of Gas \n Name of Acid \n"]], ["block_26", ["HF(g), hydrogen fluoride\nHF(aq), hydrofluoric acid\n"]], ["block_27", ["HCl(g), hydrogen chloride\nHCl(aq), hydrochloric acid\n"]], ["block_28", ["Names of Some Simple Acids\n"]]], "page_116": [["block_0", [" Oxyacids \n"]], ["block_1", ["Many compounds containing three or more elements (such as organic compounds or coordination\ncompounds) are subject to specialized nomenclature rules that you will learn later. However, we will briefly\ndiscuss the important compounds known as oxyacids , compounds that contain hydrogen, oxygen, and at least\none other element, and are bonded in such a way as to impart acidic properties to the compound (you will\nlearn the details of this in a later chapter). Typical oxyacids consist of hydrogen combined with a polyatomic,\noxygen-containing ion. To name oxyacids:\n"]], ["block_2", ["For example, consider H2CO3 (which you might be tempted to call \u201chydrogen carbonate\u201d). To name this\ncorrectly, \u201chydrogen\u201d is omitted; the \u2013ate of carbonate is replace with \u2013ic; and acid is added\u2014so its name is\ncarbonic acid. Other examples are given in Table 2.13. There are some exceptions to the general naming\nmethod (e.g., H2SO4 is called sulfuric acid, not sulfic acid, and H2SO3 is sulfurous, not sulfous, acid).\n"]], ["block_3", ["1.\nOmit \u201chydrogen\u201d\n"]], ["block_4", ["2.\nStart with the root name of the anion\n"]], ["block_5", ["3.\nReplace \u2013ate with \u2013ic, or \u2013ite with \u2013ous\n"]], ["block_6", ["4.\nAdd \u201cacid\u201d\n"]], ["block_7", [" TABLE 2.12 \n"]], ["block_8", [" Name of Gas \n Name of Acid \n"]], ["block_9", ["HBr(g), hydrogen bromide\nHBr(aq), hydrobromic acid\n"]], ["block_10", ["HI(g), hydrogen iodide\nHI(aq), hydroiodic acid\n"]], ["block_11", ["H2S(g), hydrogen sulfide\nH2S(aq), hydrosulfuric acid\n"]], ["block_12", [" TABLE 2.13 \n"]], ["block_13", [" Formula \n Anion Name \n Acid Name \n"]], ["block_14", ["HC2H3O2\nacetate\nacetic acid\n"]], ["block_15", ["HNO3\nnitrate\nnitric acid\n"]], ["block_16", ["HNO2\nnitrite\nnitrous acid\n"]], ["block_17", ["HClO4\nperchlorate\nperchloric acid\n"]], ["block_18", ["H2CO3\ncarbonate\ncarbonic acid\n"]], ["block_19", ["H2SO4\nsulfate\nsulfuric acid\n"]], ["block_20", ["H2SO3\nsulfite\nsulfurous acid\n"]], ["block_21", ["H3PO4\nphosphate\nphosphoric acid\n"]], ["block_22", ["Names of Common Oxyacids\n"]], ["block_23", [" 2.7 \u2022 Chemical Nomenclature \n 103 \n"]]], "page_117": [["block_0", [" 104 \n 2 \u2022 Key Terms \n"]], ["block_1", [" Key Terms \n"]], ["block_2", [" actinide inner transition metal in the bottom of the\n"]], ["block_3", [" alkali metal element in group 1\n alkaline earth metal element in group 2\n alpha particle ( \u03b1 particle) positively charged\n"]], ["block_4", [" anion \nnegatively charged atom or molecule\n"]], ["block_5", [" atomic mass \naverage mass of atoms of an element,\n"]], ["block_6", [" atomic mass unit (amu) \n(also, unified atomic mass\n"]], ["block_7", [" atomic number (Z) \nnumber of protons in the\n"]], ["block_8", [" binary acid compound that contains hydrogen and\n"]], ["block_9", [" binary compound compound containing two\n"]], ["block_10", [" cation \npositively charged atom or molecule\n"]], ["block_11", [" chalcogen element in group 16\n chemical symbol \none-, two-, or three-letter\n"]], ["block_12", [" covalent bond attractive force between the nuclei\n"]], ["block_13", [" covalent compound (also, molecular compound)\n"]], ["block_14", [" Dalton (Da) \nalternative unit equivalent to the\n"]], ["block_15", [" Dalton\u2019s atomic theory \nset of postulates that\n"]], ["block_16", [" electron negatively charged, subatomic particle of\n"]], ["block_17", [" empirical formula formula showing the\n"]], ["block_18", [" fundamental unit of charge \n(also called the\n"]], ["block_19", [" group vertical column of the periodic table\n halogen element in group 17\n hydrate compound containing one or more water\n"]], ["block_20", [" inert gas (also, noble gas) element in group 18\n"]], ["block_21", [" Access for free at openstax.org \n"]], ["block_22", ["bottom two rows of the periodic table\n"]], ["block_23", ["particle consisting of two protons and two\nneutrons\n"]], ["block_24", ["(contains more electrons than protons)\n"]], ["block_25", ["expressed in amu\n"]], ["block_26", ["unit, u, or Dalton, Da) unit of mass equal to\nof\n"]], ["block_27", ["the mass of a C atom\n"]], ["block_28", ["nucleus of an atom\n"]], ["block_29", ["one other element, bonded in a way that imparts\nacidic properties to the compound (ability to\nrelease Hions when dissolved in water)\n"]], ["block_30", ["different elements.\n"]], ["block_31", ["(contains fewer electrons than protons)\n"]], ["block_32", ["abbreviation used to represent an element or its\natoms\n"]], ["block_33", ["of a molecule\u2019s atoms and pairs of electrons\nbetween the atoms\n"]], ["block_34", ["composed of molecules formed by atoms of two\nor more different elements\n"]], ["block_35", ["atomic mass unit\n"]], ["block_36", ["established the fundamental properties of atoms\n"]], ["block_37", ["relatively low mass located outside the nucleus\n"]], ["block_38", ["composition of a compound given as the simplest\nwhole-number ratio of atoms\n"]], ["block_39", ["elementary charge) equals the magnitude of the\ncharge of an electron (e) with e = 1.602\n10C\n"]], ["block_40", ["molecules bound within its crystals\n"]], ["block_41", [" inner transition metal (also, lanthanide or\n"]], ["block_42", [" ion \nelectrically charged atom or molecule (contains\n"]], ["block_43", [" ionic bond electrostatic forces of attraction\n"]], ["block_44", [" ionic compound compound composed of cations\n"]], ["block_45", [" isomers compounds with the same chemical\n"]], ["block_46", [" isotopes atoms that contain the same number of\n"]], ["block_47", [" lanthanide inner transition metal in the top of the\n"]], ["block_48", [" law of constant composition \n(also, law of definite\n"]], ["block_49", [" law of definite proportions \n(also, law of constant\n"]], ["block_50", [" law of multiple proportions \nwhen two elements\n"]], ["block_51", [" main-group element (also, representative element)\n"]], ["block_52", [" mass number (A) \nsum of the numbers of neutrons\n"]], ["block_53", [" metal element that is shiny, malleable, good\n"]], ["block_54", [" metalloid element that conducts heat and\n"]], ["block_55", [" molecular compound (also, covalent compound)\n"]], ["block_56", [" molecular formula formula indicating the\n"]], ["block_57", [" monatomic ion ion composed of a single atom\n neutron uncharged, subatomic particle located in\n"]], ["block_58", [" noble gas (also, inert gas) element in group 18\n nomenclature system of rules for naming objects\n"]], ["block_59", ["actinide) element in the bottom two rows; if in the\nfirst row, also called lanthanide, or if in the\nsecond row, also called actinide\n"]], ["block_60", ["unequal numbers of protons and electrons)\n"]], ["block_61", ["between the oppositely charged ions of an ionic\ncompound\n"]], ["block_62", ["and anions combined in ratios, yielding an\nelectrically neutral substance\n"]], ["block_63", ["formula but different structures\n"]], ["block_64", ["protons but different numbers of neutrons\n"]], ["block_65", ["bottom two rows of the periodic table\n"]], ["block_66", ["proportions) all samples of a pure compound\ncontain the same elements in the same\nproportions by mass\n"]], ["block_67", ["composition) all samples of a pure compound\ncontain the same elements in the same\nproportions by mass\n"]], ["block_68", ["react to form more than one compound, a fixed\nmass of one element will react with masses of the\nother element in a ratio of small whole numbers\n"]], ["block_69", ["element in groups 1, 2, and 13\u201318\n"]], ["block_70", ["and protons in the nucleus of an atom\n"]], ["block_71", ["conductor of heat and electricity\n"]], ["block_72", ["electricity moderately well, and possesses some\nproperties of metals and some properties of\nnonmetals\n"]], ["block_73", ["composed of molecules formed by atoms of two\nor more different elements\n"]], ["block_74", ["composition of a molecule of a compound and\ngiving the actual number of atoms of each\nelement in a molecule of the compound.\n"]], ["block_75", ["the nucleus\n"]]], "page_118": [["block_0", [" nonmetal element that appears dull, poor\n"]], ["block_1", [" nucleus massive, positively charged center of an\n"]], ["block_2", [" oxyacid compound that contains hydrogen, oxygen,\n"]], ["block_3", [" oxyanion polyatomic anion composed of a central\n"]], ["block_4", [" period (also, series) horizontal row of the periodic\n"]], ["block_5", [" periodic law properties of the elements are\n"]], ["block_6", [" periodic table table of the elements that places\n"]], ["block_7", [" pnictogen element in group 15\n polyatomic ion ion composed of more than one\n"]], ["block_8", [" Key Equations \n"]], ["block_9", [" Summary \n"]], ["block_10", [" 2.1 Early Ideas in Atomic Theory \n"]], ["block_11", ["The ancient Greeks proposed that matter consists of\nextremely small particles called atoms. Dalton\npostulated that each element has a characteristic\ntype of atom that differs in properties from atoms of\nall other elements, and that atoms of different\nelements can combine in fixed, small, whole-\nnumber ratios to form compounds. Samples of a\nparticular compound all have the same elemental\nproportions by mass. When two elements form\ndifferent compounds, a given mass of one element\nwill combine with masses of the other element in a\nsmall, whole-number ratio. During any chemical\nchange, atoms are neither created nor destroyed.\n"]], ["block_12", [" 2.2 Evolution of Atomic Theory \n"]], ["block_13", ["Although no one has actually seen the inside of an\natom, experiments have demonstrated much about\natomic structure. Thomson\u2019s cathode ray tube\nshowed that atoms contain small, negatively\ncharged particles called electrons. Millikan\ndiscovered that there is a fundamental electric\ncharge\u2014the charge of an electron. Rutherford\u2019s gold\nfoil experiment showed that atoms have a small,\n"]], ["block_14", ["of interest\n"]], ["block_15", ["conductor of heat and electricity\n"]], ["block_16", ["atom made up of protons and neutrons\n"]], ["block_17", ["and one other element, bonded in a way that\nimparts acidic properties to the compound\n(ability to release Hions when dissolved in\nwater)\n"]], ["block_18", ["atom bonded to oxygen atoms\n"]], ["block_19", ["table\n"]], ["block_20", ["periodic function of their atomic numbers.\n"]], ["block_21", ["elements with similar chemical properties close\ntogether\n"]], ["block_22", [" proton positively charged, subatomic particle\n"]], ["block_23", [" representative element (also, main-group\n"]], ["block_24", [" series (also, period) horizontal row of the period\n"]], ["block_25", [" spatial isomers compounds in which the relative\n"]], ["block_26", [" structural formula shows the atoms in a molecule\n"]], ["block_27", [" structural isomer one of two substances that have\n"]], ["block_28", [" transition metal element in groups 3\u201312 (more\n"]], ["block_29", [" unified atomic mass unit (u) \nalternative unit\n"]], ["block_30", ["dense, positively charged nucleus; the positively\ncharged particles within the nucleus are called\nprotons. Chadwick discovered that the nucleus also\ncontains neutral particles called neutrons. Soddy\ndemonstrated that atoms of the same element can\ndiffer in mass; these are called isotopes.\n"]], ["block_31", [" 2.3 Atomic Structure and Symbolism \n"]], ["block_32", ["An atom consists of a small, positively charged\nnucleus surrounded by electrons. The nucleus\ncontains protons and neutrons; its diameter is about\n100,000 times smaller than that of the atom. The\nmass of one atom is usually expressed in atomic\nmass units (amu), which is referred to as the atomic\nmass. An amu is defined as exactly\nof the mass of\n"]], ["block_33", ["a carbon-12 atom and is equal to 1.6605\n10g.\n"]], ["block_34", ["Protons are relatively heavy particles with a charge\nof 1+ and a mass of 1.0073 amu. Neutrons are\nrelatively heavy particles with no charge and a mass\nof 1.0087 amu. Electrons are light particles with a\ncharge of 1\u2212 and a mass of 0.00055 amu. The\nnumber of protons in the nucleus is called the\natomic number (Z) and is the property that defines\nan atom\u2019s elemental identity. The sum of the\n"]], ["block_35", ["atom\n"]], ["block_36", ["located in the nucleus\n"]], ["block_37", ["element) element in columns 1, 2, and 12\u201318\n"]], ["block_38", ["table\n"]], ["block_39", ["orientations of the atoms in space differ\n"]], ["block_40", ["and how they are connected\n"]], ["block_41", ["the same molecular formula but different\nphysical and chemical properties because their\natoms are bonded differently\n"]], ["block_42", ["strictly defined, 3\u201311; see chapter on transition\nmetals and coordination chemistry)\n"]], ["block_43", ["equivalent to the atomic mass unit\n"]], ["block_44", [" 2 \u2022 Key Equations \n 105 \n"]]], "page_119": [["block_0", [" 106 \n 2 \u2022 Summary \n"]], ["block_1", ["numbers of protons and neutrons in the nucleus is\ncalled the mass number and, expressed in amu, is\napproximately equal to the mass of the atom. An\natom is neutral when it contains equal numbers of\nelectrons and protons.\n"]], ["block_2", ["Isotopes of an element are atoms with the same\natomic number but different mass numbers;\nisotopes of an element, therefore, differ from each\nother only in the number of neutrons within the\nnucleus. When a naturally occurring element is\ncomposed of several isotopes, the atomic mass of the\nelement represents the average of the masses of the\nisotopes involved. A chemical symbol identifies the\natoms in a substance using symbols, which are one-,\ntwo-, or three-letter abbreviations for the atoms.\n"]], ["block_3", [" 2.4 Chemical Formulas \n"]], ["block_4", ["A molecular formula uses chemical symbols and\nsubscripts to indicate the exact numbers of different\natoms in a molecule or compound. An empirical\nformula gives the simplest, whole-number ratio of\natoms in a compound. A structural formula\nindicates the bonding arrangement of the atoms in\nthe molecule. Ball-and-stick and space-filling\nmodels show the geometric arrangement of atoms in\na molecule. Isomers are compounds with the same\nmolecular formula but different arrangements of\natoms.\n"]], ["block_5", [" 2.5 The Periodic Table \n"]], ["block_6", ["The discovery of the periodic recurrence of similar\nproperties among the elements led to the\nformulation of the periodic table, in which the\nelements are arranged in order of increasing atomic\nnumber in rows known as periods and columns\nknown as groups. Elements in the same group of the\nperiodic table have similar chemical properties.\nElements can be classified as metals, metalloids,\nand nonmetals, or as a main-group elements,\ntransition metals, and inner transition metals.\nGroups are numbered 1\u201318 from left to right. The\nelements in group 1 are known as the alkali metals;\nthose in group 2 are the alkaline earth metals; those\nin 15 are the pnictogens; those in 16 are the\nchalcogens; those in 17 are the halogens; and those\nin 18 are the noble gases.\n"]], ["block_7", [" 2.6 Ionic and Molecular Compounds \n"]], ["block_8", ["Metals (particularly those in groups 1 and 2) tend to\nlose the number of electrons that would leave them\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["with the same number of electrons as in the\npreceding noble gas in the periodic table. By this\nmeans, a positively charged ion is formed. Similarly,\nnonmetals (especially those in groups 16 and 17,\nand, to a lesser extent, those in Group 15) can gain\nthe number of electrons needed to provide atoms\nwith the same number of electrons as in the next\nnoble gas in the periodic table. Thus, nonmetals\ntend to form negative ions. Positively charged ions\nare called cations, and negatively charged ions are\ncalled anions. Ions can be either monatomic\n(containing only one atom) or polyatomic\n(containing more than one atom).\n"]], ["block_11", ["Compounds that contain ions are called ionic\ncompounds. Ionic compounds generally form from\nmetals and nonmetals. Compounds that do not\ncontain ions, but instead consist of atoms bonded\ntightly together in molecules (uncharged groups of\natoms that behave as a single unit), are called\ncovalent compounds. Covalent compounds usually\nform from two nonmetals.\n"]], ["block_12", [" 2.7 Chemical Nomenclature \n"]], ["block_13", ["Chemists use nomenclature rules to clearly name\ncompounds. Ionic and molecular compounds are\nnamed using somewhat-different methods. Binary\nionic compounds typically consist of a metal and a\nnonmetal. The name of the metal is written first,\nfollowed by the name of the nonmetal with its\nending changed to \u2013ide. For example, K2O is called\npotassium oxide. If the metal can form ions with\ndifferent charges, a Roman numeral in parentheses\nfollows the name of the metal to specify its charge.\nThus, FeCl2 is iron(II) chloride and FeCl3 is iron(III)\nchloride. Some compounds contain polyatomic ions;\nthe names of common polyatomic ions should be\nmemorized. Molecular compounds can form\ncompounds with different ratios of their elements,\nso prefixes are used to specify the numbers of atoms\nof each element in a molecule of the compound.\nExamples include SF6, sulfur hexafluoride, and\nN2O4, dinitrogen tetroxide. Acids are an important\nclass of compounds containing hydrogen and having\nspecial nomenclature rules. Binary acids are named\nusing the prefix hydro-, changing the \u2013ide suffix to\n\u2013ic, and adding \u201cacid;\u201d HCl is hydrochloric acid.\nOxyacids are named by changing the ending of the\nanion (\u2013ate to \u2013ic and \u2013ite to \u2013ous), and adding\n\u201cacid;\u201d H2CO3 is carbonic acid.\n"]]], "page_120": [["block_0", [" Exercises \n"]], ["block_1", [" 2.1 Early Ideas in Atomic Theory \n"]], ["block_2", [" 4 . Samples of compound X, Y, and Z are analyzed, with results shown here.\n"]], ["block_3", [" 2.2 Evolution of Atomic Theory \n"]], ["block_4", [" 1 . In the following drawing, the green spheres represent atoms of a certain element. The purple spheres\n"]], ["block_5", [" 2 . Which postulate of Dalton\u2019s theory is consistent with the following observation concerning the weights of\n"]], ["block_6", [" 3 . Identify the postulate of Dalton\u2019s theory that is violated by the following observations: 59.95% of one\n"]], ["block_7", [" 5 . The existence of isotopes violates one of the original ideas of Dalton\u2019s atomic theory. Which one?\n 6 . How are electrons and protons similar? How are they different?\n 7 . How are protons and neutrons similar? How are they different?\n 8 . Predict and test the behavior of \u03b1 particles fired at a \u201cplum pudding\u201d model atom.\n"]], ["block_8", ["Do these data provide example(s) of the law of definite proportions, the law of multiple proportions, neither, or\nboth? What do these data tell you about compounds X, Y, and Z?\n"]], ["block_9", ["represent atoms of another element. If the spheres of different elements touch, they are part of a single\nunit of a compound. The following chemical change represented by these spheres may violate one of the\nideas of Dalton\u2019s atomic theory. Which one?\n"]], ["block_10", [{"image_0": "120_0.png", "coords": [89, 147, 323, 186]}]], ["block_11", ["reactants and products? When 100 grams of solid calcium carbonate is heated, 44 grams of carbon dioxide\nand 56 grams of calcium oxide are produced.\n"]], ["block_12", ["sample of titanium dioxide is titanium; 60.10% of a different sample of titanium dioxide is titanium.\n"]], ["block_13", ["(a) Predict the paths taken by \u03b1 particles that are fired at atoms with a Thomson\u2019s plum pudding model\nstructure. Explain why you expect the \u03b1 particles to take these paths.\n(b) If \u03b1 particles of higher energy than those in (a) are fired at plum pudding atoms, predict how their paths\nwill differ from the lower-energy \u03b1 particle paths. Explain your reasoning.\n(c) Now test your predictions from (a) and (b). Open the Rutherford Scattering simulation\n(http://openstax.org/l/16PhetScatter) and select the \u201cPlum Pudding Atom\u201d tab. Set \u201cAlpha Particles\nEnergy\u201d to \u201cmin,\u201d and select \u201cshow traces.\u201d Click on the gun to start firing \u03b1 particles. Does this match your\nprediction from (a)? If not, explain why the actual path would be that shown in the simulation. Hit the\npause button, or \u201cReset All.\u201d Set \u201cAlpha Particles Energy\u201d to \u201cmax,\u201d and start firing \u03b1 particles. Does this\nmatch your prediction from (b)? If not, explain the effect of increased energy on the actual paths as shown\nin the simulation.\n"]], ["block_14", [" Compound \n Description \n Mass of Carbon \n Mass of Hydrogen \n"]], ["block_15", ["X\nclear, colorless, liquid\n"]], ["block_16", ["Z\nclear, colorless, liquid\n"]], ["block_17", ["Y\nclear, colorless, liquid\n"]], ["block_18", ["with strong odor\n1.776 g\n0.148 g\n"]], ["block_19", ["with strong odor\n1.974 g\n0.329 g\n"]], ["block_20", ["with strong odor\n7.812 g\n0.651 g\n"]], ["block_21", [" 2 \u2022 Exercises \n 107 \n"]]], "page_121": [["block_0", [" 108 \n 2 \u2022 Exercises \n"]], ["block_1", [" 2.3 Atomic Structure and Symbolism \n"]], ["block_2", [" 10 . In what way are isotopes of a given element always different? In what way(s) are they always the same?\n 11 . Write the symbol for each of the following ions:\n"]], ["block_3", [" 12 . Write the symbol for each of the following ions:\n"]], ["block_4", [" 13 . Open the Build an Atom simulation (http://openstax.org/l/16PhetAtomBld) and click on the Atom icon.\n"]], ["block_5", [" 14 . Open the Build an Atom simulation (http://openstax.org/l/16PhetAtomBld).\n"]], ["block_6", [" 15 . Open the Build an Atom simulation (http://openstax.org/l/16PhetAtomBld).\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [" 9 . Predict and test the behavior of \u03b1 particles fired at a Rutherford atom model.\n"]], ["block_9", ["(a) Predict the paths taken by \u03b1 particles that are fired at atoms with a Rutherford atom model structure.\nExplain why you expect the \u03b1 particles to take these paths.\n(b) If \u03b1 particles of higher energy than those in (a) are fired at Rutherford atoms, predict how their paths\nwill differ from the lower-energy \u03b1 particle paths. Explain your reasoning.\n(c) Predict how the paths taken by the \u03b1 particles will differ if they are fired at Rutherford atoms of\nelements other than gold. What factor do you expect to cause this difference in paths, and why?\n(d) Now test your predictions from (a), (b), and (c). Open the Rutherford Scattering simulation\n(http://openstax.org/l/16PhetScatter) and select the \u201cRutherford Atom\u201d tab. Due to the scale of the\nsimulation, it is best to start with a small nucleus, so select \u201c20\u201d for both protons and neutrons, \u201cmin\u201d for\nenergy, show traces, and then start firing \u03b1 particles. Does this match your prediction from (a)? If not,\nexplain why the actual path would be that shown in the simulation. Pause or reset, set energy to \u201cmax,\u201d\nand start firing \u03b1 particles. Does this match your prediction from (b)? If not, explain the effect of increased\nenergy on the actual path as shown in the simulation. Pause or reset, select \u201c40\u201d for both protons and\nneutrons, \u201cmin\u201d for energy, show traces, and fire away. Does this match your prediction from (c)? If not,\nexplain why the actual path would be that shown in the simulation. Repeat this with larger numbers of\nprotons and neutrons. What generalization can you make regarding the type of atom and effect on the path\nof \u03b1 particles? Be clear and specific.\n"]], ["block_10", ["(a) the ion with a 1+ charge, atomic number 55, and mass number 133\n(b) the ion with 54 electrons, 53 protons, and 74 neutrons\n(c) the ion with atomic number 15, mass number 31, and a 3\u2212 charge\n(d) the ion with 24 electrons, 30 neutrons, and a 3+ charge\n"]], ["block_11", ["(a) the ion with a 3+ charge, 28 electrons, and a mass number of 71\n(b) the ion with 36 electrons, 35 protons, and 45 neutrons\n(c) the ion with 86 electrons, 142 neutrons, and a 4+ charge\n(d) the ion with a 2+ charge, atomic number 38, and mass number 87\n"]], ["block_12", ["(a) Pick any one of the first 10 elements that you would like to build and state its symbol.\n(b) Drag protons, neutrons, and electrons onto the atom template to make an atom of your element.\nState the numbers of protons, neutrons, and electrons in your atom, as well as the net charge and mass\nnumber.\n(c) Click on \u201cNet Charge\u201d and \u201cMass Number,\u201d check your answers to (b), and correct, if needed.\n(d) Predict whether your atom will be stable or unstable. State your reasoning.\n(e) Check the \u201cStable/Unstable\u201d box. Was your answer to (d) correct? If not, first predict what you can do to\nmake a stable atom of your element, and then do it and see if it works. Explain your reasoning.\n"]], ["block_13", ["(a) Drag protons, neutrons, and electrons onto the atom template to make a neutral atom of Oxygen-16\nand give the isotope symbol for this atom.\n(b) Now add two more electrons to make an ion and give the symbol for the ion you have created.\n"]], ["block_14", ["(a) Drag protons, neutrons, and electrons onto the atom template to make a neutral atom of Lithium-6 and\ngive the isotope symbol for this atom.\n(b) Now remove one electron to make an ion and give the symbol for the ion you have created.\n"]]], "page_122": [["block_0", [" 16 . Determine the number of protons, neutrons, and electrons in the following isotopes that are used in\n"]], ["block_1", [" 17 . The following are properties of isotopes of two elements that are essential in our diet. Determine the\n"]], ["block_2", [" 18 . Give the number of protons, electrons, and neutrons in neutral atoms of each of the following isotopes:\n"]], ["block_3", [" 19 . Give the number of protons, electrons, and neutrons in neutral atoms of each of the following isotopes:\n"]], ["block_4", [" 20 . Click on the site (http://openstax.org/l/16PhetAtomMass) and select the \u201cMix Isotopes\u201d tab, hide the\n"]], ["block_5", [" 21 . Repeat Exercise 2.20 using an element that has three naturally occurring isotopes.\n 22 . An element has the following natural abundances and isotopic masses: 90.92% abundance with 19.99\n"]], ["block_6", [" 23 . Average atomic masses listed by IUPAC are based on a study of experimental results. Bromine has two\n"]], ["block_7", [" 24 . Variations in average atomic mass may be observed for elements obtained from different sources. Lithium\n"]], ["block_8", ["medical diagnoses:\n(a) atomic number 9, mass number 18, charge of 1\u2212\n(b) atomic number 43, mass number 99, charge of 7+\n(c) atomic number 53, atomic mass number 131, charge of 1\u2212\n(d) atomic number 81, atomic mass number 201, charge of 1+\n(e) Name the elements in parts (a), (b), (c), and (d).\n"]], ["block_9", ["number of protons, neutrons and electrons in each and name them.\n(a) atomic number 26, mass number 58, charge of 2+\n(b) atomic number 53, mass number 127, charge of 1\u2212\n"]], ["block_10", ["(a)\n"]], ["block_11", ["(b)\n"]], ["block_12", ["(c)\n"]], ["block_13", ["(d)\n"]], ["block_14", ["(e)\n"]], ["block_15", ["(a)\n"]], ["block_16", ["(b)\n"]], ["block_17", ["(c)\n"]], ["block_18", ["(d)\n"]], ["block_19", ["(e)\n"]], ["block_20", ["\u201cPercent Composition\u201d and \u201cAverage Atomic Mass\u201d boxes, and then select the element boron.\n(a) Write the symbols of the isotopes of boron that are shown as naturally occurring in significant\namounts.\n(b) Predict the relative amounts (percentages) of these boron isotopes found in nature. Explain the\nreasoning behind your choice.\n(c) Add isotopes to the black box to make a mixture that matches your prediction in (b). You may drag\nisotopes from their bins or click on \u201cMore\u201d and then move the sliders to the appropriate amounts.\n(d) Reveal the \u201cPercent Composition\u201d and \u201cAverage Atomic Mass\u201d boxes. How well does your mixture\nmatch with your prediction? If necessary, adjust the isotope amounts to match your prediction.\n(e) Select \u201cNature\u2019s\u201d mix of isotopes and compare it to your prediction. How well does your prediction\ncompare with the naturally occurring mixture? Explain. If necessary, adjust your amounts to make them\nmatch \u201cNature\u2019s\u201d amounts as closely as possible.\n"]], ["block_21", ["amu, 0.26% abundance with 20.99 amu, and 8.82% abundance with 21.99 amu. Calculate the average\natomic mass of this element.\n"]], ["block_22", ["isotopes, Br and Br, whose masses (78.9183 and 80.9163 amu, respectively) and abundances (50.69%\nand 49.31%, respectively) were determined in earlier experiments. Calculate the average atomic mass of\nbromine based on these experiments.\n"]], ["block_23", ["provides an example of this. The isotopic composition of lithium from naturally occurring minerals is\n7.5% Li and 92.5% Li, which have masses of 6.01512 amu and 7.01600 amu, respectively. A commercial\nsource of lithium, recycled from a military source, was 3.75% Li (and the rest Li). Calculate the average\natomic mass values for each of these two sources.\n"]], ["block_24", [" 2 \u2022 Exercises \n 109 \n"]]], "page_123": [["block_0", [" 110 \n 2 \u2022 Exercises \n"]], ["block_1", [" 25 . The average atomic masses of some elements may vary, depending upon the sources of their ores.\n"]], ["block_2", [" 26 . The O:O abundance ratio in some meteorites is greater than that used to calculate the average atomic\n"]], ["block_3", [" 2.4 Chemical Formulas \n"]], ["block_4", [" 27 . Explain why the symbol for an atom of the element oxygen and the formula for a molecule of oxygen differ.\n 28 . Explain why the symbol for the element sulfur and the formula for a molecule of sulfur differ.\n 29 . Write the molecular and empirical formulas of the following compounds:\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", ["Naturally occurring boron consists of two isotopes with accurately known masses (B, 10.0129 amu and\n11B, 11.00931 amu). The actual atomic mass of boron can vary from 10.807 to 10.819, depending on\nwhether the mineral source is from Turkey or the United States. Calculate the percent abundances leading\nto the two values of the average atomic masses of boron from these two countries.\n"]], ["block_7", ["mass of oxygen on earth. Is the average mass of an oxygen atom in these meteorites greater than, less\nthan, or equal to that of a terrestrial oxygen atom?\n"]], ["block_8", ["(a)\n"]], ["block_9", [{"image_0": "123_0.png", "coords": [91, 242, 208, 250]}]], ["block_10", ["(b)\n"]], ["block_11", [{"image_1": "123_1.png", "coords": [91, 279, 208, 290]}]], ["block_12", ["(c)\n"]], ["block_13", [{"image_2": "123_2.png", "coords": [91, 318, 208, 362]}]], ["block_14", ["(d)\n"]], ["block_15", [{"image_3": "123_3.png", "coords": [91, 390, 208, 442]}]]], "page_124": [["block_0", [" 30 . Write the molecular and empirical formulas of the following compounds:\n"]], ["block_1", [" 31 . Determine the empirical formulas for the following compounds:\n"]], ["block_2", [" 32 . Determine the empirical formulas for the following compounds:\n"]], ["block_3", [" 33 . Write the empirical formulas for the following compounds:\n"]], ["block_4", ["(a)\n"]], ["block_5", [{"image_0": "124_0.png", "coords": [91, 82, 208, 133]}]], ["block_6", ["(b)\n"]], ["block_7", [{"image_1": "124_1.png", "coords": [91, 162, 208, 213]}]], ["block_8", ["(c)\n"]], ["block_9", [{"image_2": "124_2.png", "coords": [91, 241, 208, 292]}]], ["block_10", ["(d)\n"]], ["block_11", [{"image_3": "124_3.png", "coords": [91, 320, 208, 371]}]], ["block_12", ["(a) caffeine, C8H10N4O2\n(b) sucrose, C12H22O11\n(c) hydrogen peroxide, H2O2\n(d) glucose, C6H12O6\n(e) ascorbic acid (vitamin C), C6H8O6\n"]], ["block_13", ["(a) acetic acid, C2H4O2\n(b) citric acid, C6H8O7\n(c) hydrazine, N2H4\n(d) nicotine, C10H14N2\n(e) butane, C4H10\n"]], ["block_14", ["(a)\n"]], ["block_15", [{"image_4": "124_4.png", "coords": [91, 550, 208, 601]}]], ["block_16", ["(b)\n"]], ["block_17", [{"image_5": "124_5.png", "coords": [91, 629, 325, 679]}]], ["block_18", [" 2 \u2022 Exercises \n 111 \n"]]], "page_125": [["block_0", [" 112 \n 2 \u2022 Exercises \n"]], ["block_1", [" 34 . Open the Build a Molecule simulation (http://openstax.org/l/16molbuilding) and select the \u201cLarger\n"]], ["block_2", [" 35 . Use the Build a Molecule simulation (http://openstax.org/l/16molbuilding) to repeat Exercise 2.34, but\n"]], ["block_3", [" 36 . Use the Build a Molecule simulation (http://openstax.org/l/16molbuilding) to repeat Exercise 2.34, but\n"]], ["block_4", [" 2.5 The Periodic Table \n"]], ["block_5", [" 37 . Using the periodic table, classify each of the following elements as a metal or a nonmetal, and then further\n"]], ["block_6", [" 38 . Using the periodic table, classify each of the following elements as a metal or a nonmetal, and then further\n"]], ["block_7", [" 39 . Using the periodic table, identify the lightest member of each of the following groups:\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["Molecules\u201d tab. Select an appropriate atom\u2019s \u201cKit\u201d to build a molecule with two carbon and six hydrogen\natoms. Drag atoms into the space above the \u201cKit\u201d to make a molecule. A name will appear when you have\nmade an actual molecule that exists (even if it is not the one you want). You can use the scissors tool to\nseparate atoms if you would like to change the connections. Click on \u201c3D\u201d to see the molecule, and look at\nboth the space-filling and ball-and-stick possibilities.\n(a) Draw the structural formula of this molecule and state its name.\n(b) Can you arrange these atoms in any way to make a different compound?\n"]], ["block_10", ["build a molecule with two carbons, six hydrogens, and one oxygen.\n(a) Draw the structural formula of this molecule and state its name.\n(b) Can you arrange these atoms to make a different molecule? If so, draw its structural formula and state\nits name.\n(c) How are the molecules drawn in (a) and (b) the same? How do they differ? What are they called (the\ntype of relationship between these molecules, not their names).?\n"]], ["block_11", ["build a molecule with three carbons, seven hydrogens, and one chlorine.\n(a) Draw the structural formula of this molecule and state its name.\n(b) Can you arrange these atoms to make a different molecule? If so, draw its structural formula and state\nits name.\n(c) How are the molecules drawn in (a) and (b) the same? How do they differ? What are they called (the\ntype of relationship between these molecules, not their names)?\n"]], ["block_12", ["classify each as a main-group (representative) element, transition metal, or inner transition metal:\n(a) uranium\n(b) bromine\n(c) strontium\n(d) neon\n(e) gold\n(f) americium\n(g) rhodium\n(h) sulfur\n(i) carbon\n(j) potassium\n"]], ["block_13", ["classify each as a main-group (representative) element, transition metal, or inner transition metal:\n(a) cobalt\n(b) europium\n(c) iodine\n(d) indium\n(e) lithium\n(f) oxygen\n(g) cadmium\n(h) terbium\n(i) rhenium\n"]], ["block_14", ["(a) noble gases\n(b) alkaline earth metals\n(c) alkali metals\n(d) chalcogens\n"]]], "page_126": [["block_0", [" 40 . Using the periodic table, identify the heaviest member of each of the following groups:\n"]], ["block_1", [" 41 . Use the periodic table to give the name and symbol for each of the following elements:\n"]], ["block_2", [" 42 . Use the periodic table to give the name and symbol for each of the following elements:\n"]], ["block_3", [" 43 . Write a symbol for each of the following neutral isotopes. Include the atomic number and mass number\n"]], ["block_4", [" 44 . Write a symbol for each of the following neutral isotopes. Include the atomic number and mass number\n"]], ["block_5", [" 2.6 Ionic and Molecular Compounds \n"]], ["block_6", [" 45 . Using the periodic table, predict whether the following chlorides are ionic or covalent: KCl, NCl3, ICl,\n"]], ["block_7", [" 46 . Using the periodic table, predict whether the following chlorides are ionic or covalent: SiCl4, PCl3, CaCl2,\n"]], ["block_8", [" 47 . For each of the following compounds, state whether it is ionic or covalent. If it is ionic, write the symbols\n"]], ["block_9", [" 48 . For each of the following compounds, state whether it is ionic or covalent, and if it is ionic, write the\n"]], ["block_10", ["(a) alkali metals\n(b) chalcogens\n(c) noble gases\n(d) alkaline earth metals\n"]], ["block_11", ["(a) the noble gas in the same period as germanium\n(b) the alkaline earth metal in the same period as selenium\n(c) the halogen in the same period as lithium\n(d) the chalcogen in the same period as cadmium\n"]], ["block_12", ["(a) the halogen in the same period as the alkali metal with 11 protons\n(b) the alkaline earth metal in the same period with the neutral noble gas with 18 electrons\n(c) the noble gas in the same row as an isotope with 30 neutrons and 25 protons\n(d) the noble gas in the same period as gold\n"]], ["block_13", ["for each.\n(a) the alkali metal with 11 protons and a mass number of 23\n(b) the noble gas element with 75 neutrons in its nucleus and 54 electrons in the neutral atom\n(c) the isotope with 33 protons and 40 neutrons in its nucleus\n(d) the alkaline earth metal with 88 electrons and 138 neutrons\n"]], ["block_14", ["for each.\n(a) the chalcogen with a mass number of 125\n(b) the halogen whose longest-lived isotope is radioactive\n(c) the noble gas, used in lighting, with 10 electrons and 10 neutrons\n(d) the lightest alkali metal with three neutrons\n"]], ["block_15", ["MgCl2, PCl5, and CCl4.\n"]], ["block_16", ["CsCl, CuCl2, and CrCl3.\n"]], ["block_17", ["for the ions involved:\n(a) NF3\n(b) BaO\n(c) (NH4)2CO3\n(d) Sr(H2PO4)2\n(e) IBr\n(f) Na2O\n"]], ["block_18", ["symbols for the ions involved:\n(a) KClO4\n(b) Mg(C2H3O2)2\n(c) H2S\n(d) Ag2S\n(e) N2Cl4\n(f) Co(NO3)2\n"]], ["block_19", [" 2 \u2022 Exercises \n 113 \n"]]], "page_127": [["block_0", [" 114 \n 2 \u2022 Exercises \n"]], ["block_1", [" 49 . For each of the following pairs of ions, write the formula of the compound they will form:\n"]], ["block_2", [" 50 . For each of the following pairs of ions, write the formula of the compound they will form:\n"]], ["block_3", [" 2.7 Chemical Nomenclature \n"]], ["block_4", [" 51 . Name the following compounds:\n"]], ["block_5", [" 52 . Name the following compounds:\n"]], ["block_6", [" 53 . Write the formulas of the following compounds:\n"]], ["block_7", [" 54 . Write the formulas of the following compounds:\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["(a) Ca, S\n"]], ["block_10", ["(b)\n(c) Al, Br\n"]], ["block_11", ["(d) Na,\n(e) Mg,\n"]], ["block_12", ["(a) K, O\n"]], ["block_13", ["(b)\n(c) Al, O\n"]], ["block_14", ["(d) Na,\n(e) Ba,\n"]], ["block_15", ["(a) CsCl\n(b) BaO\n(c) K2S\n(d) BeCl2\n(e) HBr\n(f) AlF3\n"]], ["block_16", ["(a) NaF\n(b) Rb2O\n(c) BCl3\n(d) H2Se\n(e) P4O6\n(f) ICl3\n"]], ["block_17", ["(a) rubidium bromide\n(b) magnesium selenide\n(c) sodium oxide\n(d) calcium chloride\n(e) hydrogen fluoride\n(f) gallium phosphide\n(g) aluminum bromide\n(h) ammonium sulfate\n"]], ["block_18", ["(a) lithium carbonate\n(b) sodium perchlorate\n(c) barium hydroxide\n(d) ammonium carbonate\n(e) sulfuric acid\n(f) calcium acetate\n(g) magnesium phosphate\n(h) sodium sulfite\n"]]], "page_128": [["block_0", [" 55 . Write the formulas of the following compounds:\n"]], ["block_1", [" 56 . Write the formulas of the following compounds:\n"]], ["block_2", [" 57 . Each of the following compounds contains a metal that can exhibit more than one ionic charge. Name\n"]], ["block_3", [" 58 . Each of the following compounds contains a metal that can exhibit more than one ionic charge. Name\n"]], ["block_4", [" 59 . The following ionic compounds are found in common household products. Write the formulas for each\n"]], ["block_5", [" 60 . The following ionic compounds are found in common household products. Name each of the compounds:\n"]], ["block_6", [" 61 . What are the IUPAC names of the following compounds?\n"]], ["block_7", ["(a) chlorine dioxide\n(b) dinitrogen tetraoxide\n(c) potassium phosphide\n(d) silver(I) sulfide\n(e) aluminum fluoride trihydrate\n(f) silicon dioxide\n"]], ["block_8", ["(a) barium chloride\n(b) magnesium nitride\n(c) sulfur dioxide\n(d) nitrogen trichloride\n(e) dinitrogen trioxide\n(f) tin(IV) chloride\n"]], ["block_9", ["these compounds:\n(a) Cr2O3\n(b) FeCl2\n(c) CrO3\n(d) TiCl4\n(e) CoCl2\u00b76H2O\n(f) MoS2\n"]], ["block_10", ["these compounds:\n(a) NiCO3\n(b) MoO3\n(c) Co(NO3)2\n(d) V2O5\n(e) MnO2\n(f) Fe2O3\n"]], ["block_11", ["compound:\n(a) potassium phosphate\n(b) copper(II) sulfate\n(c) calcium chloride\n(d) titanium(IV) oxide\n(e) ammonium nitrate\n(f) sodium bisulfate (the common name for sodium hydrogen sulfate)\n"]], ["block_12", ["(a) Ca(H2PO4)2\n(b) FeSO4\n(c) CaCO3\n(d) MgO\n(e) NaNO2\n(f) KI\n"]], ["block_13", ["(a) manganese dioxide\n(b) mercurous chloride (Hg2Cl2)\n(c) ferric nitrate [Fe(NO3)3]\n(d) titanium tetrachloride\n(e) cupric bromide (CuBr2)\n"]], ["block_14", [" 2 \u2022 Exercises \n 115 \n"]]], "page_129": [["block_0", [" 116 \n 2 \u2022 Exercises \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_130": [["block_0", ["CHAPTER 3\nComposition of Substances and\nSolutions\n"]], ["block_1", [{"image_0": "130_0.png", "coords": [72, 131, 622, 385]}]], ["block_2", [" Figure 3.1 \nThe water in a swimming pool is a complex mixture of substances whose relative amounts must be\n"]], ["block_3", ["carefully maintained to ensure the health and comfort of people using the pool. (credit: modification of work by Vic\nBrincat)\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 3.1 Formula Mass and the Mole Concept \n 3.2 Determining Empirical and Molecular Formulas \n 3.3 Molarity \n 3.4 Other Units for Solution Concentrations \n"]], ["block_6", [" INTRODUCTION \n"]], ["block_7", ["therapy. Since it is impractical to refill large pools with fresh water on a frequent basis, pool water is regularly\ntreated with chemicals to prevent the growth of harmful bacteria and algae. Proper pool maintenance requires\nregular additions of various chemical compounds in carefully measured amounts. For example, the relative\namount of calcium ion, Ca, in the water should be maintained within certain limits to prevent eye irritation\nand avoid damage to the pool bed and plumbing. To maintain proper calcium levels, calcium cations are added\nto the water in the form of an ionic compound that also contains anions; thus, it is necessary to know both the\nrelative amount of Cain the compound and the volume of water in the pool in order to achieve the proper\ncalcium level. Quantitative aspects of the composition of substances (such as the calcium-containing\ncompound) and mixtures (such as the pool water) are the subject of this chapter.\n"]], ["block_8", ["Swimming pools have long been a popular means of recreation, exercise, and physical\n"]]], "page_131": [["block_0", [" 118 \n 3 \u2022 Composition of Substances and Solutions \n"]], ["block_1", [" 3.1 Formula Mass and the Mole Concept \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["Many argue that modern chemical science began when scientists started exploring the quantitative as well as\nthe qualitative aspects of chemistry. For example, Dalton\u2019s atomic theory was an attempt to explain the results\nof measurements that allowed him to calculate the relative masses of elements combined in various\ncompounds. Understanding the relationship between the masses of atoms and the chemical formulas of\ncompounds allows us to quantitatively describe the composition of substances.\n"]], ["block_4", [" Formula Mass \n"]], ["block_5", ["An earlier chapter of this text described the development of the atomic mass unit, the concept of average\natomic masses, and the use of chemical formulas to represent the elemental makeup of substances. These\nideas can be extended to calculate the formula mass of a substance by summing the average atomic masses of\nall the atoms represented in the substance\u2019s formula.\n"]], ["block_6", [" Formula Mass for Covalent Substances \nFor covalent substances, the formula represents the numbers and types of atoms composing a single molecule\nof the substance; therefore, the formula mass may be correctly referred to as a molecular mass. Consider\nchloroform (CHCl3), a covalent compound once used as a surgical anesthetic and now primarily used in the\nproduction of tetrafluoroethylene, the building block for the \"anti-stick\" polymer, Teflon. The molecular\nformula of chloroform indicates that a single molecule contains one carbon atom, one hydrogen atom, and\nthree chlorine atoms. The average molecular mass of a chloroform molecule is therefore equal to the sum of\nthe average atomic masses of these atoms. Figure 3.2 outlines the calculations used to derive the molecular\nmass of chloroform, which is 119.37 amu.\n"]], ["block_7", [{"image_0": "131_0.png", "coords": [72, 431, 540, 545]}]], ["block_8", [" FIGURE 3.2 \nThe average mass of a chloroform molecule, CHCl3, is 119.37 amu, which is the sum of the average\n"]], ["block_9", ["atomic masses of each of its constituent atoms. The model shows the molecular structure of chloroform.\n"]], ["block_10", ["Likewise, the molecular mass of an aspirin molecule, C9H8O4, is the sum of the atomic masses of nine carbon\natoms, eight hydrogen atoms, and four oxygen atoms, which amounts to 180.15 amu (Figure 3.3).\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["\u2022\nCalculate formula masses for covalent and ionic compounds\n"]], ["block_13", ["\u2022\nDefine the amount unit mole and the related quantity Avogadro\u2019s number Explain the relation between mass,\nmoles, and numbers of atoms or molecules, and perform calculations deriving these quantities from one\nanother\n"]]], "page_132": [["block_0", [" FIGURE 3.3 \nThe average mass of an aspirin molecule is 180.15 amu. The model shows the molecular structure of\n"]], ["block_1", ["aspirin, C9H8O4.\n"]], ["block_2", [" Computing Molecular Mass for a Covalent Compound \n"]], ["block_3", ["Ibuprofen, C13H18O2, is a covalent compound and the active ingredient in several popular nonprescription\npain medications, such as Advil and Motrin. What is the molecular mass (amu) for this compound?\n"]], ["block_4", [" Solution \n"]], ["block_5", ["Molecules of this compound are composed of 13 carbon atoms, 18 hydrogen atoms, and 2 oxygen atoms.\nFollowing the approach described above, the average molecular mass for this compound is therefore:\n"]], ["block_6", [{"image_0": "132_0.png", "coords": [72, 333, 502, 447]}]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["Acetaminophen, C8H9NO2, is a covalent compound and the active ingredient in several popular\nnonprescription pain medications, such as Tylenol. What is the molecular mass (amu) for this compound?\n"]], ["block_9", [" Answer: \n151.16 amu\n"]], ["block_10", [" Formula Mass for Ionic Compounds \nIonic compounds are composed of discrete cations and anions combined in ratios to yield electrically neutral\nbulk matter. The formula mass for an ionic compound is calculated in the same way as the formula mass for\ncovalent compounds: by summing the average atomic masses of all the atoms in the compound\u2019s formula.\nKeep in mind, however, that the formula for an ionic compound does not represent the composition of a\ndiscrete molecule, so it may not correctly be referred to as the \u201cmolecular mass.\u201d\n"]], ["block_11", ["As an example, consider sodium chloride, NaCl, the chemical name for common table salt. Sodium chloride is\nan ionic compound composed of sodium cations, Na, and chloride anions, Cl, combined in a 1:1 ratio. The\nformula mass for this compound is computed as 58.44 amu (see Figure 3.4).\n"]], ["block_12", [{"image_1": "132_1.png", "coords": [94, 57, 517, 171]}]], ["block_13", ["EXAMPLE 3.1\n"]], ["block_14", [" 3.1 \u2022 Formula Mass and the Mole Concept \n 119 \n"]]], "page_133": [["block_0", [" 120 \n 3 \u2022 Composition of Substances and Solutions \n"]], ["block_1", [{"image_0": "133_0.png", "coords": [72, 57, 540, 151]}]], ["block_2", [" FIGURE 3.4 \nTable salt, NaCl, contains an array of sodium and chloride ions combined in a 1:1 ratio. Its formula\n"]], ["block_3", ["mass is 58.44 amu.\n"]], ["block_4", ["Note that the average masses of neutral sodium and chlorine atoms were used in this computation, rather than\nthe masses for sodium cations and chlorine anions. This approach is perfectly acceptable when computing the\nformula mass of an ionic compound. Even though a sodium cation has a slightly smaller mass than a sodium\natom (since it is missing an electron), this difference will be offset by the fact that a chloride anion is slightly\nmore massive than a chloride atom (due to the extra electron). Moreover, the mass of an electron is negligibly\nsmall with respect to the mass of a typical atom. Even when calculating the mass of an isolated ion, the missing\nor additional electrons can generally be ignored, since their contribution to the overall mass is negligible,\nreflected only in the nonsignificant digits that will be lost when the computed mass is properly rounded. The\nfew exceptions to this guideline are very light ions derived from elements with precisely known atomic\nmasses.\n"]], ["block_5", [" Computing Formula Mass for an Ionic Compound \n"]], ["block_6", ["Aluminum sulfate, Al2(SO4)3, is an ionic compound that is used in the manufacture of paper and in various\nwater purification processes. What is the formula mass (amu) of this compound?\n"]], ["block_7", [" Solution \n"]], ["block_8", ["The formula for this compound indicates it contains Aland SO4ions combined in a 2:3 ratio. For purposes\nof computing a formula mass, it is helpful to rewrite the formula in the simpler format, Al2S3O12. Following the\napproach outlined above, the formula mass for this compound is calculated as follows:\n"]], ["block_9", [{"image_1": "133_1.png", "coords": [72, 458, 504, 573]}]], ["block_10", [" Check Your Learning \n"]], ["block_11", ["Calcium phosphate, Ca3(PO4)2, is an ionic compound and a common anti-caking agent added to food products.\nWhat is the formula mass (amu) of calcium phosphate?\n"]], ["block_12", [" Answer: \n310.18 amu\n"]], ["block_13", [" The Mole \n"]], ["block_14", ["The identity of a substance is defined not only by the types of atoms or ions it contains, but by the quantity of\neach type of atom or ion. For example, water, H2O, and hydrogen peroxide, H2O2, are alike in that their\nrespective molecules are composed of hydrogen and oxygen atoms. However, because a hydrogen peroxide\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["EXAMPLE 3.2\n"]]], "page_134": [["block_0", ["molecule contains two oxygen atoms, as opposed to the water molecule, which has only one, the two\nsubstances exhibit very different properties. Today, sophisticated instruments allow the direct measurement\nof these defining microscopic traits; however, the same traits were originally derived from the measurement of\nmacroscopic properties (the masses and volumes of bulk quantities of matter) using relatively simple tools\n(balances and volumetric glassware). This experimental approach required the introduction of a new unit for\namount of substances, the mole, which remains indispensable in modern chemical science.\n"]], ["block_1", ["The mole is an amount unit similar to familiar units like pair, dozen, gross, etc. It provides a specific measure\nof the number of atoms or molecules in a sample of matter. One Latin connotation for the word \u201cmole\u201d is \u201clarge\nmass\u201d or \u201cbulk,\u201d which is consistent with its use as the name for this unit. The mole provides a link between an\neasily measured macroscopic property, bulk mass, and an extremely important fundamental property,\nnumber of atoms, molecules, and so forth. A mole of substance is that amount in which there are 6.02214076\n"]], ["block_2", [" Avogadro\u2019s number (N A ) or the Avogadro constant in honor of Italian scientist Amedeo Avogadro. This\nconstant is properly reported with an explicit unit of \u201cper mole,\u201d a conveniently rounded version being 6.022\n10/mol.\n"]], ["block_3", ["Consistent with its definition as an amount unit, 1 mole of any element contains the same number of atoms as\n1 mole of any other element. The masses of 1 mole of different elements, however, are different, since the\nmasses of the individual atoms are drastically different. The molar mass of an element (or compound) is the\nmass in grams of 1 mole of that substance, a property expressed in units of grams per mole (g/mol) (see Figure\n3.5).\n"]], ["block_4", [" FIGURE 3.5 \nEach sample contains 6.022\n10atoms \u20141.00 mol of atoms. From left to right (top row): 65.4 g\n"]], ["block_5", ["zinc, 12.0 g carbon, 24.3 g magnesium, and 63.5 g copper. From left to right (bottom row): 32.1 g sulfur, 28.1 g\nsilicon, 207 g lead, and 118.7 g tin. (credit: modification of work by Mark Ott)\n"]], ["block_6", ["The molar mass of any substance is numerically equivalent to its atomic or formula weight in amu. Per the\namu definition, a single C atom weighs 12 amu (its atomic mass is 12 amu). A mole of C weighs 12 g (its\nmolar mass is 12 g/mol). This relationship holds for all elements, since their atomic masses are measured\nrelative to that of the amu-reference substance, C. Extending this principle, the molar mass of a compound in\ngrams is likewise numerically equivalent to its formula mass in amu (Figure 3.6).\n"]], ["block_7", ["10discrete entities (atoms or molecules). This large number is a fundamental constant known as\n"]], ["block_8", [{"image_0": "134_0.png", "coords": [180, 328, 432, 495]}]], ["block_9", [" 3.1 \u2022 Formula Mass and the Mole Concept \n 121 \n"]]], "page_135": [["block_0", [" 122 \n 3 \u2022 Composition of Substances and Solutions \n"]], ["block_1", [" FIGURE 3.6 \nEach sample contains 6.02\n10molecules or formula units\u20141.00 mol of the compound or element.\n"]], ["block_2", ["Clock-wise from the upper left: 130.2 g of C8H17OH (1-octanol, formula mass 130.2 amu), 454.4 g of HgI2\n(mercury(II) iodide, formula mass 454.4 amu), 32.0 g of CH3OH (methanol, formula mass 32.0 amu) and 256.5 g of\nS8 (sulfur, formula mass 256.5 amu). (credit: Sahar Atwa)\n"]], ["block_3", ["While atomic mass and molar mass are numerically equivalent, keep in mind that they are vastly different in\nterms of scale, as represented by the vast difference in the magnitudes of their respective units (amu versus g).\nTo appreciate the enormity of the mole, consider a small drop of water weighing about 0.03 g (see Figure 3.7).\nAlthough this represents just a tiny fraction of 1 mole of water (~18 g), it contains more water molecules than\ncan be clearly imagined. If the molecules were distributed equally among the roughly seven billion people on\nearth, each person would receive more than 100 billion molecules.\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", [" Element \n Average Atomic Mass (amu) \n Molar Mass (g/mol) \n Atoms/Mole \n"]], ["block_6", ["Na\n22.99\n22.99\n6.022\n10\n"]], ["block_7", ["Cl\n35.45\n35.45\n6.022\n10\n"]], ["block_8", ["H\n1.008\n1.008\n6.022\n10\n"]], ["block_9", ["O\n16.00\n16.00\n6.022\n10\n"]], ["block_10", ["C\n12.01\n12.01\n6.022\n10\n"]], ["block_11", [{"image_0": "135_0.png", "coords": [189, 57, 423, 213]}]]], "page_136": [["block_0", [" FIGURE 3.7 \nThe number of molecules in a single droplet of water is roughly 100 billion times greater than the\n"]], ["block_1", ["number of people on earth. (credit: \u201ctanakawho\u201d/Wikimedia commons)\n"]], ["block_2", ["The mole is used in chemistry to represent 6.022\n10of something, but it can be difficult to conceptualize\n"]], ["block_3", ["such a large number. Watch this video (http://openstax.org/l/16molevideo) and then complete the \u201cThink\u201d\nquestions that follow. Explore more about the mole by reviewing the information under \u201cDig Deeper.\u201d\n"]], ["block_4", ["The relationships between formula mass, the mole, and Avogadro\u2019s number can be applied to compute various\nquantities that describe the composition of substances and compounds, as demonstrated in the next several\nexample problems.\n"]], ["block_5", [" Deriving Moles from Grams for an Element \n"]], ["block_6", ["According to nutritional guidelines from the US Department of Agriculture, the estimated average requirement\nfor dietary potassium is 4.7 g. What is the estimated average requirement of potassium in moles?\n"]], ["block_7", [" Solution \n"]], ["block_8", ["The mass of K is provided, and the corresponding amount of K in moles is requested. Referring to the periodic\ntable, the atomic mass of K is 39.10 amu, and so its molar mass is 39.10 g/mol. The given mass of K (4.7 g) is a\nbit more than one-tenth the molar mass (39.10 g), so a reasonable \u201cballpark\u201d estimate of the number of moles\nwould be slightly greater than 0.1 mol.\n"]], ["block_9", ["The molar amount of a substance may be calculated by dividing its mass (g) by its molar mass (g/mol):\n"]], ["block_10", [{"image_0": "136_0.png", "coords": [72, 618, 306, 671]}]], ["block_11", ["The factor-label method supports this mathematical approach since the unit \u201cg\u201d cancels and the answer has\nunits of \u201cmol:\u201d\n"]], ["block_12", ["LINK TO LEARNING\n"]], ["block_13", ["EXAMPLE 3.3\n"]], ["block_14", [{"image_1": "136_1.png", "coords": [189, 57, 423, 290]}]], ["block_15", [" 3.1 \u2022 Formula Mass and the Mole Concept \n 123 \n"]]], "page_137": [["block_0", [" 124 \n 3 \u2022 Composition of Substances and Solutions \n"]], ["block_1", ["The calculated magnitude (0.12 mol K) is consistent with our ballpark expectation, since it is a bit greater than\n0.1 mol.\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["Beryllium is a light metal used to fabricate transparent X-ray windows for medical imaging instruments. How\nmany moles of Be are in a thin-foil window weighing 3.24 g?\n"]], ["block_4", [" Answer: \n0.360 mol\n"]], ["block_5", [" Deriving Grams from Moles for an Element \n"]], ["block_6", ["A liter of air contains 9.2\n10mol argon. What is the mass of Ar in a liter of air?\n"]], ["block_7", [" Solution \n"]], ["block_8", ["The molar amount of Ar is provided and must be used to derive the corresponding mass in grams. Since the\namount of Ar is less than 1 mole, the mass will be less than the mass of 1 mole of Ar, approximately 40 g. The\nmolar amount in question is approximately one-one thousandth (~10) of a mole, and so the corresponding\nmass should be roughly one-one thousandth of the molar mass (~0.04 g):\n"]], ["block_9", [{"image_0": "137_0.png", "coords": [72, 356, 306, 409]}]], ["block_10", ["In this case, logic dictates (and the factor-label method supports) multiplying the provided amount (mol) by\nthe molar mass (g/mol):\n"]], ["block_11", ["The result is in agreement with our expectations, around 0.04 g Ar.\n"]], ["block_12", [" Check Your Learning \n"]], ["block_13", ["What is the mass of 2.561 mol of gold?\n"]], ["block_14", [" Answer: \n504.4 g\n"]], ["block_15", [" Deriving Number of Atoms from Mass for an Element \n"]], ["block_16", ["Copper is commonly used to fabricate electrical wire (Figure 3.8). How many copper atoms are in 5.00 g of\ncopper wire?\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["EXAMPLE 3.4\n"]], ["block_19", ["EXAMPLE 3.5\n"]]], "page_138": [["block_0", [" Solution \n"]], ["block_1", ["The number of Cu atoms in the wire may be conveniently derived from its mass by a two-step computation:\nfirst calculating the molar amount of Cu, and then using Avogadro\u2019s number (NA) to convert this molar amount\nto number of Cu atoms:\n"]], ["block_2", [{"image_0": "138_0.png", "coords": [72, 311, 504, 373]}]], ["block_3", ["Considering that the provided sample mass (5.00 g) is a little less than one-tenth the mass of 1 mole of Cu (~64\ng), a reasonable estimate for the number of atoms in the sample would be on the order of one-tenth NA, or\napproximately 10Cu atoms. Carrying out the two-step computation yields:\n"]], ["block_4", ["The factor-label method yields the desired cancellation of units, and the computed result is on the order of\n10as expected.\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["A prospector panning for gold in a river collects 15.00 g of pure gold. How many Au atoms are in this quantity\nof gold?\n"]], ["block_7", [" Answer: \n4.586\n10Au atoms\n"]], ["block_8", [" Deriving Moles from Grams for a Compound \n"]], ["block_9", ["Our bodies synthesize protein from amino acids. One of these amino acids is glycine, which has the molecular\nformula C2H5O2N. How many moles of glycine molecules are contained in 28.35 g of glycine?\n"]], ["block_10", [" Solution \n"]], ["block_11", ["Derive the number of moles of a compound from its mass following the same procedure used for an element in\nExample 3.3:\n"]], ["block_12", ["EXAMPLE 3.6\n"]], ["block_13", [" FIGURE 3.8 \nCopper wire is composed of many, many atoms of Cu. (credit: Emilian Robert Vicol)\n"]], ["block_14", [{"image_1": "138_1.png", "coords": [241, 57, 370, 230]}]], ["block_15", [" 3.1 \u2022 Formula Mass and the Mole Concept \n 125 \n"]]], "page_139": [["block_0", [" 126 \n 3 \u2022 Composition of Substances and Solutions \n"]], ["block_1", [{"image_0": "139_0.png", "coords": [72, 57, 306, 110]}]], ["block_2", ["The molar mass of glycine is required for this calculation, and it is computed in the same fashion as its\nmolecular mass. One mole of glycine, C2H5O2N, contains 2 moles of carbon, 5 moles of hydrogen, 2 moles of\noxygen, and 1 mole of nitrogen:\n"]], ["block_3", [{"image_1": "139_1.png", "coords": [72, 157, 504, 305]}]], ["block_4", ["The provided mass of glycine (~28 g) is a bit more than one-third the molar mass (~75 g/mol), so the computed\nresult is expected to be a bit greater than one-third of a mole (~0.33 mol). Dividing the compound\u2019s mass by its\nmolar mass yields:\n"]], ["block_5", ["This result is consistent with the rough estimate.\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["How many moles of sucrose, C12H22O11, are in a 25-g sample of sucrose?\n"]], ["block_8", [" Answer: \n0.073 mol\n"]], ["block_9", [" Deriving Grams from Moles for a Compound \n"]], ["block_10", ["Vitamin C is a covalent compound with the molecular formula C6H8O6. The recommended daily dietary\nallowance of vitamin C for children aged 4\u20138 years is 1.42\n10mol. What is the mass of this allowance in\n"]], ["block_11", ["grams?\n"]], ["block_12", [" Solution \n"]], ["block_13", ["As for elements, the mass of a compound can be derived from its molar amount as shown:\n"]], ["block_14", [{"image_2": "139_2.png", "coords": [72, 614, 423, 667]}]], ["block_15", ["The molar mass for this compound is computed to be 176.124 g/mol. The given number of moles is a very\nsmall fraction of a mole (~10or one-ten thousandth); therefore, the corresponding mass is expected to be\nabout one-ten thousandth of the molar mass (~0.02 g). Performing the calculation yields:\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["EXAMPLE 3.7\n"]]], "page_140": [["block_0", ["This is consistent with the anticipated result.\n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["What is the mass of 0.443 mol of hydrazine, N2H4?\n"]], ["block_3", [" Answer: \n14.2 g\n"]], ["block_4", [" Deriving the Number of Atoms and Molecules from the Mass of a Compound \n"]], ["block_5", ["A packet of an artificial sweetener contains 40.0 mg of saccharin (C7H5NO3S), which has the structural\nformula:\n"]], ["block_6", [{"image_0": "140_0.png", "coords": [72, 272, 189, 364]}]], ["block_7", ["Given that saccharin has a molar mass of 183.18 g/mol, how many saccharin molecules are in a 40.0-mg\n(0.0400-g) sample of saccharin? How many carbon atoms are in the same sample?\n"]], ["block_8", [" Solution \n"]], ["block_9", ["The number of molecules in a given mass of compound is computed by first deriving the number of moles, as\ndemonstrated in Example 3.6, and then multiplying by Avogadro\u2019s number:\n"]], ["block_10", [{"image_1": "140_1.png", "coords": [72, 445, 504, 509]}]], ["block_11", ["Using the provided mass and molar mass for saccharin yields:\n"]], ["block_12", ["The compound\u2019s formula shows that each molecule contains seven carbon atoms, and so the number of C\natoms in the provided sample is:\n"]], ["block_13", [" Check Your Learning \n"]], ["block_14", ["How many C4H10 molecules are contained in 9.213 g of this compound? How many hydrogen atoms?\n"]], ["block_15", [" Answer: \n9.545\n10molecules C4 H10; 9.545\n10atoms H\n"]], ["block_16", ["EXAMPLE 3.8\n"]], ["block_17", [" 3.1 \u2022 Formula Mass and the Mole Concept \n 127 \n"]]], "page_141": [["block_0", [" 128 \n 3 \u2022 Composition of Substances and Solutions \n"]], ["block_1", [" Counting Neurotransmitter Molecules in the Brain \nThe brain is the control center of the central nervous system (Figure 3.9). It sends and receives signals to and\nfrom muscles and other internal organs to monitor and control their functions; it processes stimuli detected\nby sensory organs to guide interactions with the external world; and it houses the complex physiological\nprocesses that give rise to our intellect and emotions. The broad field of neuroscience spans all aspects of the\nstructure and function of the central nervous system, including research on the anatomy and physiology of the\nbrain. Great progress has been made in brain research over the past few decades, and the BRAIN Initiative, a\nfederal initiative announced in 2013, aims to accelerate and capitalize on these advances through the\nconcerted efforts of various industrial, academic, and government agencies (more details available at\nwww.whitehouse.gov/share/brain-initiative).\n"]], ["block_2", [" FIGURE 3.9 \n(a) A typical human brain weighs about 1.5 kg and occupies a volume of roughly 1.1 L. (b) Information\n"]], ["block_3", ["is transmitted in brain tissue and throughout the central nervous system by specialized cells called neurons\n(micrograph shows cells at 1600\u00d7 magnification).\n"]], ["block_4", ["Specialized cells called neurons transmit information between different parts of the central nervous system by\nway of electrical and chemical signals. Chemical signaling occurs at the interface between different neurons\nwhen one of the cells releases molecules (called neurotransmitters) that diffuse across the small gap between\nthe cells (called the synapse) and bind to the surface of the other cell. These neurotransmitter molecules are\nstored in small intracellular structures called vesicles that fuse to the cell membrane and then break open to\nrelease their contents when the neuron is appropriately stimulated. This process is called exocytosis (see\nFigure 3.10). One neurotransmitter that has been very extensively studied is dopamine, C8H11NO2. Dopamine\nis involved in various neurological processes that impact a wide variety of human behaviors. Dysfunctions in\nthe dopamine systems of the brain underlie serious neurological diseases such as Parkinson\u2019s and\nschizophrenia.\n"]], ["block_5", [" FIGURE 3.10 \n(a) Chemical signals are transmitted from neurons to other cells by the release of neurotransmitter\n"]], ["block_6", ["molecules into the small gaps (synapses) between the cells. (b) Dopamine, C8H11NO2, is a neurotransmitter\ninvolved in a number of neurological processes.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", ["HOW SCIENCES INTERCONNECT\n"]], ["block_9", [{"image_0": "141_0.png", "coords": [180, 224, 432, 349]}]], ["block_10", [{"image_1": "141_1.png", "coords": [180, 528, 432, 668]}]]], "page_142": [["block_0", ["One important aspect of the complex processes related to dopamine signaling is the number of\nneurotransmitter molecules released during exocytosis. Since this number is a central factor in determining\nneurological response (and subsequent human thought and action), it is important to know how this number\nchanges with certain controlled stimulations, such as the administration of drugs. It is also important to\nunderstand the mechanism responsible for any changes in the number of neurotransmitter molecules\nreleased\u2014for example, some dysfunction in exocytosis, a change in the number of vesicles in the neuron, or a\nchange in the number of neurotransmitter molecules in each vesicle.\n"]], ["block_1", ["Significant progress has been made recently in directly measuring the number of dopamine molecules stored\nin individual vesicles and the amount actually released when the vesicle undergoes exocytosis. Using\nminiaturized probes that can selectively detect dopamine molecules in very small amounts, scientists have\ndetermined that the vesicles of a certain type of mouse brain neuron contain an average of 30,000 dopamine\nmolecules per vesicle (about\nmol or 50 zmol). Analysis of these neurons from mice subjected to\n"]], ["block_2", ["various drug therapies shows significant changes in the average number of dopamine molecules contained in\nindividual vesicles, increasing or decreasing by up to three-fold, depending on the specific drug used. These\nstudies also indicate that not all of the dopamine in a given vesicle is released during exocytosis, suggesting\nthat it may be possible to regulate the fraction released using pharmaceutical therapies.\n"]], ["block_3", [" 3.2 Determining Empirical and Molecular Formulas \n"]], ["block_4", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_5", ["The previous section discussed the relationship between the bulk mass of a substance and the number of\natoms or molecules it contains (moles). Given the chemical formula of the substance, one may determine the\namount of the substance (moles) from its mass, and vice versa. But what if the chemical formula of a substance\nis unknown? In this section, these same principles will be applied to derive the chemical formulas of unknown\nsubstances from experimental mass measurements.\n"]], ["block_6", [" Percent Composition \n"]], ["block_7", ["The elemental makeup of a compound defines its chemical identity, and chemical formulas are the most\nsuccinct way of representing this elemental makeup. When a compound\u2019s formula is unknown, measuring the\nmass of each of its constituent elements is often the first step in the process of determining the formula\nexperimentally. The results of these measurements permit the calculation of the compound\u2019s percent \n composition , defined as the percentage by mass of each element in the compound. For example, consider a\ngaseous compound composed solely of carbon and hydrogen. The percent composition of this compound\ncould be represented as follows:\n"]], ["block_8", ["If analysis of a 10.0-g sample of this gas showed it to contain 2.5 g H and 7.5 g C, the percent composition\nwould be calculated to be 25% H and 75% C:\n"]], ["block_9", ["1 Omiatek, Donna M., Amanda J. Bressler, Ann-Sofie Cans, Anne M. Andrews, Michael L. Heien, and Andrew G. Ewing. \u201cThe Real\nCatecholamine Content of Secretory Vesicles in the CNS Revealed by Electrochemical Cytometry.\u201d Scientific Report 3 (2013): 1447,\naccessed January 14, 2015, doi:10.1038/srep01447.\n"]], ["block_10", ["\u2022\nCompute the percent composition of a compound\n"]], ["block_11", ["\u2022\nDetermine the empirical formula of a compound\n"]], ["block_12", ["\u2022\nDetermine the molecular formula of a compound\n"]], ["block_13", [" 3.2 \u2022 Determining Empirical and Molecular Formulas \n 129 \n"]]], "page_143": [["block_0", [" 130 \n 3 \u2022 Composition of Substances and Solutions \n"]], ["block_1", [" Calculation of Percent Composition \n"]], ["block_2", ["Analysis of a 12.04-g sample of a liquid compound composed of carbon, hydrogen, and nitrogen showed it to\ncontain 7.34 g C, 1.85 g H, and 2.85 g N. What is the percent composition of this compound?\n"]], ["block_3", [" Solution \n"]], ["block_4", ["To calculate percent composition, divide the experimentally derived mass of each element by the overall mass\nof the compound, and then convert to a percentage:\n"]], ["block_5", ["The analysis results indicate that the compound is 61.0% C, 15.4% H, and 23.7% N by mass.\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["A 24.81-g sample of a gaseous compound containing only carbon, oxygen, and chlorine is determined to\ncontain 3.01 g C, 4.00 g O, and 17.81 g Cl. What is this compound\u2019s percent composition?\n"]], ["block_8", [" Answer: \n12.1% C, 16.1% O, 71.79% Cl\n"]], ["block_9", [" Determining Percent Composition from Molecular or Empirical Formulas \nPercent composition is also useful for evaluating the relative abundance of a given element in different\ncompounds of known formulas. As one example, consider the common nitrogen-containing fertilizers\nammonia (NH3), ammonium nitrate (NH4NO3), and urea (CH4N2O). The element nitrogen is the active\ningredient for agricultural purposes, so the mass percentage of nitrogen in the compound is a practical and\neconomic concern for consumers choosing among these fertilizers. For these sorts of applications, the percent\ncomposition of a compound is easily derived from its formula mass and the atomic masses of its constituent\nelements. A molecule of NH3 contains one N atom weighing 14.01 amu and three H atoms weighing a total of (3\n"]], ["block_10", ["and its percent composition is:\n"]], ["block_11", ["This same approach may be taken considering a pair of molecules, a dozen molecules, or a mole of molecules,\netc. The latter amount is most convenient and would simply involve the use of molar masses instead of atomic\nand formula masses, as demonstrated Example 3.10. As long as the molecular or empirical formula of the\ncompound in question is known, the percent composition may be derived from the atomic or molar masses of\nthe compound's elements.\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["1.008 amu) = 3.024 amu. The formula mass of ammonia is therefore (14.01 amu + 3.024 amu) = 17.03 amu,\n"]], ["block_14", ["EXAMPLE 3.9\n"]]], "page_144": [["block_0", [" Determining Percent Composition from a Molecular Formula \n"]], ["block_1", ["Aspirin is a compound with the molecular formula C9H8O4. What is its percent composition?\n"]], ["block_2", [" Solution \n"]], ["block_3", ["To calculate the percent composition, the masses of C, H, and O in a known mass of C9H8O4 are needed. It is\nconvenient to consider 1 mol of C9H8O4 and use its molar mass (180.159 g/mole, determined from the\nchemical formula) to calculate the percentages of each of its elements:\n"]], ["block_4", ["Note that these percentages sum to equal 100.00% when appropriately rounded.\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["To three significant digits, what is the mass percentage of iron in the compound Fe2O3?\n"]], ["block_7", [" Answer: \n69.9% Fe\n"]], ["block_8", [" Determination of Empirical Formulas \n"]], ["block_9", ["As previously mentioned, the most common approach to determining a compound\u2019s chemical formula is to\nfirst measure the masses of its constituent elements. However, keep in mind that chemical formulas represent\nthe relative numbers, not masses, of atoms in the substance. Therefore, any experimentally derived data\ninvolving mass must be used to derive the corresponding numbers of atoms in the compound. This is\naccomplished using molar masses to convert the mass of each element to a number of moles. These molar\namounts are used to compute whole-number ratios that can be used to derive the empirical formula of the\nsubstance. Consider a sample of compound determined to contain 1.71 g C and 0.287 g H. The corresponding\nnumbers of atoms (in moles) are:\n"]], ["block_10", ["Thus, this compound may be represented by the formula C0.142H0.284. Per convention, formulas contain whole-\nnumber subscripts, which can be achieved by dividing each subscript by the smaller subscript:\n"]], ["block_11", ["(Recall that subscripts of \u201c1\u201d are not written but rather assumed if no other number is present.)\n"]], ["block_12", ["The empirical formula for this compound is thus CH2. This may or not be the compound\u2019s molecular formula\n"]], ["block_13", ["EXAMPLE 3.10\n"]], ["block_14", [" 3.2 \u2022 Determining Empirical and Molecular Formulas \n 131 \n"]]], "page_145": [["block_0", [" 132 \n 3 \u2022 Composition of Substances and Solutions \n"]], ["block_1", ["as well; however, additional information is needed to make that determination (as discussed later in this\nsection).\n"]], ["block_2", ["Consider as another example a sample of compound determined to contain 5.31 g Cl and 8.40 g O. Following\nthe same approach yields a tentative empirical formula of:\n"]], ["block_3", ["In this case, dividing by the smallest subscript still leaves us with a decimal subscript in the empirical formula.\nTo convert this into a whole number, multiply each of the subscripts by two, retaining the same atom ratio and\nyielding Cl2O7 as the final empirical formula.\n"]], ["block_4", ["In summary, empirical formulas are derived from experimentally measured element masses by:\n"]], ["block_5", ["Figure 3.11 outlines this procedure in flow chart fashion for a substance containing elements A and X.\n"]], ["block_6", [{"image_0": "145_0.png", "coords": [72, 297, 540, 404]}]], ["block_7", [" Determining a Compound\u2019s Empirical Formula from the Masses of Its Elements \n"]], ["block_8", ["A sample of the black mineral hematite (Figure 3.12), an oxide of iron found in many iron ores, contains 34.97\ng of iron and 15.03 g of oxygen. What is the empirical formula of hematite?\n"]], ["block_9", [" Solution \n"]], ["block_10", ["This problem provides the mass in grams of each element. Begin by finding the moles of each:\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["1.\nDeriving the number of moles of each element from its mass\n"]], ["block_13", ["2.\nDividing each element\u2019s molar amount by the smallest molar amount to yield subscripts for a tentative\nempirical formula\n"]], ["block_14", ["3.\nMultiplying all coefficients by an integer, if necessary, to ensure that the smallest whole-number ratio of\nsubscripts is obtained\n"]], ["block_15", [" FIGURE 3.11 \nThe empirical formula of a compound can be derived from the masses of all elements in the sample.\n"]], ["block_16", ["EXAMPLE 3.11\n"]], ["block_17", [" FIGURE 3.12 \nHematite is an iron oxide that is used in jewelry. (credit: Mauro Cateb)\n"]], ["block_18", [{"image_1": "145_1.png", "coords": [189, 506, 423, 650]}]]], "page_146": [["block_0", ["Next, derive the iron-to-oxygen molar ratio by dividing by the lesser number of moles:\n"]], ["block_1", ["The ratio is 1.000 mol of iron to 1.500 mol of oxygen (Fe1O1.5). Finally, multiply the ratio by two to get the\nsmallest possible whole number subscripts while still maintaining the correct iron-to-oxygen ratio:\n"]], ["block_2", ["The empirical formula is Fe2O3.\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["What is the empirical formula of a compound if a sample contains 0.130 g of nitrogen and 0.370 g of oxygen?\n"]], ["block_5", [" Answer: \nN2O5\n"]], ["block_6", ["For additional worked examples illustrating the derivation of empirical formulas, watch the brief video\n(http://openstax.org/l/16empforms) clip.\n"]], ["block_7", [" Deriving Empirical Formulas from Percent Composition \nFinally, with regard to deriving empirical formulas, consider instances in which a compound\u2019s percent\ncomposition is available rather than the absolute masses of the compound\u2019s constituent elements. In such\ncases, the percent composition can be used to calculate the masses of elements present in any convenient\nmass of compound; these masses can then be used to derive the empirical formula in the usual fashion.\n"]], ["block_8", [" Determining an Empirical Formula from Percent Composition \n"]], ["block_9", ["The bacterial fermentation of grain to produce ethanol forms a gas with a percent composition of 27.29% C\nand 72.71% O (Figure 3.13). What is the empirical formula for this gas?\n"]], ["block_10", ["LINK TO LEARNING\n"]], ["block_11", ["EXAMPLE 3.12\n"]], ["block_12", [" 3.2 \u2022 Determining Empirical and Molecular Formulas \n 133 \n"]]], "page_147": [["block_0", [" 134 \n 3 \u2022 Composition of Substances and Solutions \n"]], ["block_1", [" FIGURE 3.13 \nAn oxide of carbon is removed from these fermentation tanks through the large copper pipes at the\n"]], ["block_2", ["top. (credit: \u201cDual Freq\u201d/Wikimedia Commons)\n"]], ["block_3", [" Solution \n"]], ["block_4", ["Since the scale for percentages is 100, it is most convenient to calculate the mass of elements present in a\nsample weighing 100 g. The calculation is \u201cmost convenient\u201d because, per the definition for percent\ncomposition, the mass of a given element in grams is numerically equivalent to the element\u2019s mass\npercentage. This numerical equivalence results from the definition of the \u201cpercentage\u201d unit, whose name is\nderived from the Latin phrase per centum meaning \u201cby the hundred.\u201d Considering this definition, the mass\npercentages provided may be more conveniently expressed as fractions:\n"]], ["block_5", ["The molar amounts of carbon and oxygen in a 100-g sample are calculated by dividing each element\u2019s mass by\nits molar mass:\n"]], ["block_6", ["Coefficients for the tentative empirical formula are derived by dividing each molar amount by the lesser of the\ntwo:\n"]], ["block_7", ["Since the resulting ratio is one carbon to two oxygen atoms, the empirical formula is CO2.\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["What is the empirical formula of a compound containing 40.0% C, 6.71% H, and 53.28% O?\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [{"image_0": "147_0.png", "coords": [189, 57, 423, 281]}]]], "page_148": [["block_0", [" Answer: \nCH2O\n"]], ["block_1", [" Derivation of Molecular Formulas \n"]], ["block_2", ["Recall that empirical formulas are symbols representing the relative numbers of a compound\u2019s elements.\nDetermining the absolute numbers of atoms that compose a single molecule of a covalent compound requires\nknowledge of both its empirical formula and its molecular mass or molar mass. These quantities may be\ndetermined experimentally by various measurement techniques. Molecular mass, for example, is often\nderived from the mass spectrum of the compound (see discussion of this technique in the previous chapter on\natoms and molecules). Molar mass can be measured by a number of experimental methods, many of which\nwill be introduced in later chapters of this text.\n"]], ["block_3", ["Molecular formulas are derived by comparing the compound\u2019s molecular or molar mass to its empirical \n formula mass . As the name suggests, an empirical formula mass is the sum of the average atomic masses of all\nthe atoms represented in an empirical formula. If the molecular (or molar) mass of the substance is known, it\nmay be divided by the empirical formula mass to yield the number of empirical formula units per molecule (n):\n"]], ["block_4", ["The molecular formula is then obtained by multiplying each subscript in the empirical formula by n, as shown\nby the generic empirical formula AxBy:\n"]], ["block_5", ["For example, consider a covalent compound whose empirical formula is determined to be CH2O. The empirical\nformula mass for this compound is approximately 30 amu (the sum of 12 amu for one C atom, 2 amu for two H\natoms, and 16 amu for one O atom). If the compound\u2019s molecular mass is determined to be 180 amu, this\nindicates that molecules of this compound contain six times the number of atoms represented in the empirical\nformula:\n"]], ["block_6", ["Molecules of this compound are then represented by molecular formulas whose subscripts are six times\ngreater than those in the empirical formula:\n"]], ["block_7", ["Note that this same approach may be used when the molar mass (g/mol) instead of the molecular mass (amu)\nis used. In this case, one mole of empirical formula units and molecules is considered, as opposed to single\nunits and molecules.\n"]], ["block_8", [" Determination of the Molecular Formula for Nicotine \n"]], ["block_9", ["Nicotine, an alkaloid in the nightshade family of plants that is mainly responsible for the addictive nature of\ncigarettes, contains 74.02% C, 8.710% H, and 17.27% N. If 40.57 g of nicotine contains 0.2500 mol nicotine,\nwhat is the molecular formula?\n"]], ["block_10", [" Solution \n"]], ["block_11", ["Determining the molecular formula from the provided data will require comparison of the compound\u2019s\nempirical formula mass to its molar mass. As the first step, use the percent composition to derive the\ncompound\u2019s empirical formula. Assuming a convenient, a 100-g sample of nicotine yields the following molar\namounts of its elements:\n"]], ["block_12", ["EXAMPLE 3.13\n"]], ["block_13", [" 3.2 \u2022 Determining Empirical and Molecular Formulas \n 135 \n"]]], "page_149": [["block_0", [" 136 \n 3 \u2022 Composition of Substances and Solutions \n"]], ["block_1", ["Next, calculate the molar ratios of these elements relative to the least abundant element, N.\n"]], ["block_2", ["The C-to-N and H-to-N molar ratios are adequately close to whole numbers, and so the empirical formula is\nC5H7N. The empirical formula mass for this compound is therefore 81.13 amu/formula unit, or 81.13 g/mol\nformula unit.\n"]], ["block_3", ["Calculate the molar mass for nicotine from the given mass and molar amount of compound:\n"]], ["block_4", ["Comparing the molar mass and empirical formula mass indicates that each nicotine molecule contains two\nformula units:\n"]], ["block_5", ["Finally, derive the molecular formula for nicotine from the empirical formula by multiplying each subscript by\ntwo:\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["What is the molecular formula of a compound with a percent composition of 49.47% C, 5.201% H, 28.84% N,\nand 16.48% O, and a molecular mass of 194.2 amu?\n"]], ["block_8", [" Answer: \nC8H10N4O2\n"]], ["block_9", [" 3.3 Molarity \n"]], ["block_10", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_11", ["Preceding sections of this chapter focused on the composition of substances: samples of matter that contain\nonly one type of element or compound. However, mixtures\u2014samples of matter containing two or more\nsubstances physically combined\u2014are more commonly encountered in nature than are pure substances.\nSimilar to a pure substance, the relative composition of a mixture plays an important role in determining its\nproperties. The relative amount of oxygen in a planet\u2019s atmosphere determines its ability to sustain aerobic\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["\u2022\nDescribe the fundamental properties of solutions\n"]], ["block_14", ["\u2022\nCalculate solution concentrations using molarity\n"]], ["block_15", ["\u2022\nPerform dilution calculations using the dilution equation\n"]]], "page_150": [["block_0", ["life. The relative amounts of iron, carbon, nickel, and other elements in steel (a mixture known as an \u201calloy\u201d)\ndetermine its physical strength and resistance to corrosion. The relative amount of the active ingredient in a\nmedicine determines its effectiveness in achieving the desired pharmacological effect. The relative amount of\nsugar in a beverage determines its sweetness (see Figure 3.14). This section will describe one of the most\ncommon ways in which the relative compositions of mixtures may be quantified.\n"]], ["block_1", [" FIGURE 3.14 \nSugar is one of many components in the complex mixture known as coffee. The amount of sugar in a\n"]], ["block_2", ["given amount of coffee is an important determinant of the beverage\u2019s sweetness. (credit: Jane Whitney)\n"]], ["block_3", [" Solutions \n"]], ["block_4", ["Solutions have previously been defined as homogeneous mixtures, meaning that the composition of the\nmixture (and therefore its properties) is uniform throughout its entire volume. Solutions occur frequently in\nnature and have also been implemented in many forms of manmade technology. A more thorough treatment\nof solution properties is provided in the chapter on solutions and colloids, but provided here is an introduction\nto some of the basic properties of solutions.\n"]], ["block_5", ["The relative amount of a given solution component is known as its concentration . Often, though not always, a\nsolution contains one component with a concentration that is significantly greater than that of all other\ncomponents. This component is called the solvent and may be viewed as the medium in which the other\ncomponents are dispersed, or dissolved . Solutions in which water is the solvent are, of course, very common\non our planet. A solution in which water is the solvent is called an aqueous solution .\n"]], ["block_6", ["A solute is a component of a solution that is typically present at a much lower concentration than the solvent.\nSolute concentrations are often described with qualitative terms such as dilute (of relatively low\nconcentration) and concentrated (of relatively high concentration).\n"]], ["block_7", ["Concentrations may be quantitatively assessed using a wide variety of measurement units, each convenient for\nparticular applications. Molarity (M) is a useful concentration unit for many applications in chemistry.\nMolarity is defined as the number of moles of solute in exactly 1 liter (1 L) of the solution:\n"]], ["block_8", [" Calculating Molar Concentrations \n"]], ["block_9", ["A 355-mL soft drink sample contains 0.133 mol of sucrose (table sugar). What is the molar concentration of\nsucrose in the beverage?\n"]], ["block_10", ["EXAMPLE 3.14\n"]], ["block_11", [{"image_0": "150_0.png", "coords": [189, 126, 423, 332]}]], ["block_12", [" 3.3 \u2022 Molarity \n 137 \n"]]], "page_151": [["block_0", [" 138 \n 3 \u2022 Composition of Substances and Solutions \n"]], ["block_1", [" Solution \n"]], ["block_2", ["Since the molar amount of solute and the volume of solution are both given, the molarity can be calculated\nusing the definition of molarity. Per this definition, the solution volume must be converted from mL to L:\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["A teaspoon of table sugar contains about 0.01 mol sucrose. What is the molarity of sucrose if a teaspoon of\nsugar has been dissolved in a cup of tea with a volume of 200 mL?\n"]], ["block_5", [" Answer: \n0.05 M\n"]], ["block_6", [" Deriving Moles and Volumes from Molar Concentrations \n"]], ["block_7", ["How much sugar (mol) is contained in a modest sip (~10 mL) of the soft drink from Example 3.14?\n"]], ["block_8", [" Solution \n"]], ["block_9", ["Rearrange the definition of molarity to isolate the quantity sought, moles of sugar, then substitute the value for\nmolarity derived in Example 3.14, 0.375 M:\n"]], ["block_10", [" Check Your Learning \n"]], ["block_11", ["What volume (mL) of the sweetened tea described in Example 3.14 contains the same amount of sugar (mol) as\n10 mL of the soft drink in this example?\n"]], ["block_12", [" Answer: \n80 mL\n"]], ["block_13", [" Calculating Molar Concentrations from the Mass of Solute \n"]], ["block_14", ["Distilled white vinegar (Figure 3.15) is a solution of acetic acid, CH3CO2H, in water. A 0.500-L vinegar solution\ncontains 25.2 g of acetic acid. What is the concentration of the acetic acid solution in units of molarity?\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["EXAMPLE 3.15\n"]], ["block_17", ["EXAMPLE 3.16\n"]]], "page_152": [["block_0", [" Solution \n"]], ["block_1", ["As in previous examples, the definition of molarity is the primary equation used to calculate the quantity\nsought. Since the mass of solute is provided instead of its molar amount, use the solute\u2019s molar mass to obtain\nthe amount of solute in moles:\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["Calculate the molarity of 6.52 g of CoCl2 (128.9 g/mol) dissolved in an aqueous solution with a total volume of\n75.0 mL.\n"]], ["block_4", [" Answer: \n0.674 M\n"]], ["block_5", [" Determining the Mass of Solute in a Given Volume of Solution \n"]], ["block_6", ["How many grams of NaCl are contained in 0.250 L of a 5.30-M solution?\n"]], ["block_7", [" Solution \n"]], ["block_8", ["The volume and molarity of the solution are specified, so the amount (mol) of solute is easily computed as\ndemonstrated in Example 3.15:\n"]], ["block_9", ["EXAMPLE 3.17\n"]], ["block_10", [" FIGURE 3.15 \nDistilled white vinegar is a solution of acetic acid in water.\n"]], ["block_11", [{"image_0": "152_0.png", "coords": [189, 57, 423, 280]}]], ["block_12", [" 3.3 \u2022 Molarity \n 139 \n"]]], "page_153": [["block_0", [" 140 \n 3 \u2022 Composition of Substances and Solutions \n"]], ["block_1", ["Finally, this molar amount is used to derive the mass of NaCl:\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["How many grams of CaCl2 (110.98 g/mol) are contained in 250.0 mL of a 0.200-M solution of calcium chloride?\n"]], ["block_4", [" Answer: \n5.55 g CaCl2\n"]], ["block_5", ["When performing calculations stepwise, as in Example 3.17, it is important to refrain from rounding any\nintermediate calculation results, which can lead to rounding errors in the final result. In Example 3.17, the\nmolar amount of NaCl computed in the first step, 1.325 mol, would be properly rounded to 1.32 mol if it were\nto be reported; however, although the last digit (5) is not significant, it must be retained as a guard digit in the\nintermediate calculation. If the guard digit had not been retained, the final calculation for the mass of NaCl\nwould have been 77.1 g, a difference of 0.3 g.\n"]], ["block_6", ["In addition to retaining a guard digit for intermediate calculations, rounding errors may also be avoided by\nperforming computations in a single step (see Example 3.18). This eliminates intermediate steps so that only\nthe final result is rounded.\n"]], ["block_7", [" Determining the Volume of Solution Containing a Given Mass of Solute \n"]], ["block_8", ["In Example 3.16, the concentration of acetic acid in white vinegar was determined to be 0.839 M. What volume\nof vinegar contains 75.6 g of acetic acid?\n"]], ["block_9", [" Solution \n"]], ["block_10", ["First, use the molar mass to calculate moles of acetic acid from the given mass:\n"]], ["block_11", ["Then, use the molarity of the solution to calculate the volume of solution containing this molar amount of\nsolute:\n"]], ["block_12", ["Combining these two steps into one yields:\n"]], ["block_13", [" Check Your Learning \n"]], ["block_14", ["What volume of a 1.50-M KBr solution contains 66.0 g KBr?\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["EXAMPLE 3.18\n"]]], "page_154": [["block_0", [" Answer: \n0.370 L\n"]], ["block_1", [" Dilution of Solutions \n"]], ["block_2", [" Dilution is the process whereby the concentration of a solution is lessened by the addition of solvent. For\nexample, a glass of iced tea becomes increasingly diluted as the ice melts. The water from the melting ice\nincreases the volume of the solvent (water) and the overall volume of the solution (iced tea), thereby reducing\nthe relative concentrations of the solutes that give the beverage its taste (Figure 3.16).\n"]], ["block_3", [" FIGURE 3.16 \nBoth solutions contain the same mass of copper nitrate. The solution on the right is more dilute\n"]], ["block_4", ["because the copper nitrate is dissolved in more solvent. (credit: Mark Ott)\n"]], ["block_5", ["Dilution is also a common means of preparing solutions of a desired concentration. By adding solvent to a\nmeasured portion of a more concentrated stock solution, a solution of lesser concentration may be prepared.\nFor example, commercial pesticides are typically sold as solutions in which the active ingredients are far more\nconcentrated than is appropriate for their application. Before they can be used on crops, the pesticides must\nbe diluted. This is also a very common practice for the preparation of a number of common laboratory\nreagents.\n"]], ["block_6", ["A simple mathematical relationship can be used to relate the volumes and concentrations of a solution before\nand after the dilution process. According to the definition of molarity, the number of moles of solute in a\nsolution (n) is equal to the product of the solution\u2019s molarity (M) and its volume in liters (L):\n"]], ["block_7", ["Expressions like these may be written for a solution before and after it is diluted:\n"]], ["block_8", ["where the subscripts \u201c1\u201d and \u201c2\u201d refer to the solution before and after the dilution, respectively. Since the\ndilution process does not change the amount of solute in the solution, n1 = n2. Thus, these two equations may\nbe set equal to one another:\n"]], ["block_9", ["This relation is commonly referred to as the dilution equation. Although this equation uses molarity as the unit\nof concentration and liters as the unit of volume, other units of concentration and volume may be used as long\nas the units properly cancel per the factor-label method. Reflecting this versatility, the dilution equation is\noften written in the more general form:\n"]], ["block_10", ["where C and V are concentration and volume, respectively.\n"]], ["block_11", [{"image_0": "154_0.png", "coords": [189, 182, 423, 320]}]], ["block_12", [" 3.3 \u2022 Molarity \n 141 \n"]]], "page_155": [["block_0", [" 142 \n 3 \u2022 Composition of Substances and Solutions \n"]], ["block_1", ["Use the simulation (http://openstax.org/l/16Phetsolvents) to explore the relations between solute amount,\nsolution volume, and concentration and to confirm the dilution equation.\n"]], ["block_2", [" Determining the Concentration of a Diluted Solution \n"]], ["block_3", ["If 0.850 L of a 5.00-M solution of copper nitrate, Cu(NO3)2, is diluted to a volume of 1.80 L by the addition of\nwater, what is the molarity of the diluted solution?\n"]], ["block_4", [" Solution \n"]], ["block_5", ["The stock concentration, C1, and volume, V1, are provided as well as the volume of the diluted solution, V2.\nRearrange the dilution equation to isolate the unknown property, the concentration of the diluted solution, C2:\n"]], ["block_6", ["Since the stock solution is being diluted by more than two-fold (volume is increased from 0.85 L to 1.80 L), the\ndiluted solution\u2019s concentration is expected to be less than one-half 5 M. This ballpark estimate will be\ncompared to the calculated result to check for any gross errors in computation (for example, such as an\nimproper substitution of the given quantities). Substituting the given values for the terms on the right side of\nthis equation yields:\n"]], ["block_7", ["This result compares well to our ballpark estimate (it\u2019s a bit less than one-half the stock concentration, 5 M).\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["What is the concentration of the solution that results from diluting 25.0 mL of a 2.04-M solution of CH3OH to\n500.0 mL?\n"]], ["block_10", [" Answer: \n0.102 M CH3OH\n"]], ["block_11", [" Volume of a Diluted Solution \n"]], ["block_12", ["What volume of 0.12 M HBr can be prepared from 11 mL (0.011 L) of 0.45 M HBr?\n"]], ["block_13", [" Solution \n"]], ["block_14", ["Provided are the volume and concentration of a stock solution, V1 and C1, and the concentration of the\nresultant diluted solution, C2. Find the volume of the diluted solution, V2 by rearranging the dilution equation\nto isolate V2:\n"]], ["block_15", ["Since the diluted concentration (0.12 M) is slightly more than one-fourth the original concentration (0.45 M),\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["LINK TO LEARNING\n"]], ["block_18", ["EXAMPLE 3.19\n"]], ["block_19", ["EXAMPLE 3.20\n"]]], "page_156": [["block_0", ["Since the concentration of the diluted solution 0.100 M is roughly one-sixteenth that of the stock solution (1.59\nM), the volume of the stock solution is expected to be about one-sixteenth that of the diluted solution, or\naround 0.3 liters. Substituting the given values and solving for the unknown volume yields:\n"]], ["block_1", ["the volume of the diluted solution is expected to be roughly four times the original volume, or around 44 mL.\nSubstituting the given values and solving for the unknown volume yields:\n"]], ["block_2", ["The volume of the 0.12-M solution is 0.041 L (41 mL). The result is reasonable and compares well with the\nrough estimate.\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["A laboratory experiment calls for 0.125 M HNO3. What volume of 0.125 M HNO3 can be prepared from 0.250 L\nof 1.88 M HNO3?\n"]], ["block_5", [" Answer: \n3.76 L\n"]], ["block_6", [" Volume of a Concentrated Solution Needed for Dilution \n"]], ["block_7", ["What volume of 1.59 M KOH is required to prepare 5.00 L of 0.100 M KOH?\n"]], ["block_8", [" Solution \n"]], ["block_9", ["Given are the concentration of a stock solution, C1, and the volume and concentration of the resultant diluted\nsolution, V2 and C2. Find the volume of the stock solution, V1 by rearranging the dilution equation to isolate V1:\n"]], ["block_10", ["Thus, 0.314 L of the 1.59-M solution is needed to prepare the desired solution. This result is consistent with\nthe rough estimate.\n"]], ["block_11", [" Check Your Learning \n"]], ["block_12", ["What volume of a 0.575-M solution of glucose, C6H12O6, can be prepared from 50.00 mL of a 3.00-M glucose\nsolution?\n"]], ["block_13", [" Answer: \n0.261 L\n"]], ["block_14", ["EXAMPLE 3.21\n"]], ["block_15", [" 3.3 \u2022 Molarity \n 143 \n"]]], "page_157": [["block_0", [" 144 \n 3 \u2022 Composition of Substances and Solutions \n"]], ["block_1", ["Mass percentage is also referred to by similar names such as percent mass, percent weight, weight/weight\npercent, and other variations on this theme. The most common symbol for mass percentage is simply the\npercent sign, %, although more detailed symbols are often used including %mass, %weight, and (w/w)%. Use\nof these more detailed symbols can prevent confusion of mass percentages with other types of percentages,\nsuch as volume percentages (to be discussed later in this section).\n"]], ["block_2", [" 3.4 Other Units for Solution Concentrations \n"]], ["block_3", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_4", ["The previous section introduced molarity, a very useful measurement unit for evaluating the concentration of\nsolutions. However, molarity is only one measure of concentration. This section will describe some other units\nof concentration that are commonly used in various applications, either for convenience or by convention.\n"]], ["block_5", [" Mass Percentage \n"]], ["block_6", ["Earlier in this chapter, percent composition was introduced as a measure of the relative amount of a given\nelement in a compound. Percentages are also commonly used to express the composition of mixtures,\nincluding solutions. The mass percentage of a solution component is defined as the ratio of the component\u2019s\nmass to the solution\u2019s mass, expressed as a percentage:\n"]], ["block_7", ["Mass percentages are popular concentration units for consumer products. The label of a typical liquid bleach\nbottle (Figure 3.17) cites the concentration of its active ingredient, sodium hypochlorite (NaOCl), as being\n7.4%. A 100.0-g sample of bleach would therefore contain 7.4 g of NaOCl.\n"]], ["block_8", [" FIGURE 3.17 \nLiquid bleach is an aqueous solution of sodium hypochlorite (NaOCl). This brand has a concentration\n"]], ["block_9", ["of 7.4% NaOCl by mass.\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["\u2022\nDefine the concentration units of mass percentage, volume percentage, mass-volume percentage, parts-per-\nmillion (ppm), and parts-per-billion (ppb)\n"]], ["block_12", ["\u2022\nPerform computations relating a solution\u2019s concentration and its components\u2019 volumes and/or masses using\nthese units\n"]], ["block_13", [{"image_0": "157_0.png", "coords": [130, 427, 481, 680]}]]], "page_158": [["block_0", [" Calculation of Percent by Mass \n"]], ["block_1", ["A 5.0-g sample of spinal fluid contains 3.75 mg (0.00375 g) of glucose. What is the percent by mass of glucose\nin spinal fluid?\n"]], ["block_2", [" Solution \n"]], ["block_3", ["The spinal fluid sample contains roughly 4 mg of glucose in 5000 mg of fluid, so the mass fraction of glucose\nshould be a bit less than one part in 1000, or about 0.1%. Substituting the given masses into the equation\ndefining mass percentage yields:\n"]], ["block_4", ["The computed mass percentage agrees with our rough estimate (it\u2019s a bit less than 0.1%).\n"]], ["block_5", ["Note that while any mass unit may be used to compute a mass percentage (mg, g, kg, oz, and so on), the same\nunit must be used for both the solute and the solution so that the mass units cancel, yielding a dimensionless\nratio. In this case, the solute mass unit in the numerator was converted from mg to g to match the units in the\ndenominator. Alternatively, the spinal fluid mass unit in the denominator could have been converted from g to\nmg instead. As long as identical mass units are used for both solute and solution, the computed mass\npercentage will be correct.\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["A bottle of a tile cleanser contains 135 g of HCl and 775 g of water. What is the percent by mass of HCl in this\ncleanser?\n"]], ["block_8", [" Answer: \n14.8%\n"]], ["block_9", [" Calculations using Mass Percentage \n"]], ["block_10", ["\u201cConcentrated\u201d hydrochloric acid is an aqueous solution of 37.2% HCl that is commonly used as a laboratory\nreagent. The density of this solution is 1.19 g/mL. What mass of HCl is contained in 0.500 L of this solution?\n"]], ["block_11", [" Solution \n"]], ["block_12", ["The HCl concentration is near 40%, so a 100-g portion of this solution would contain about 40 g of HCl. Since\nthe solution density isn\u2019t greatly different from that of water (1 g/mL), a reasonable estimate of the HCl mass in\n500 g (0.5 L) of the solution is about five times greater than that in a 100 g portion, or 5\n40 = 200 g. In order to\n"]], ["block_13", ["derive the mass of solute in a solution from its mass percentage, the mass of the solution must be known.\nUsing the solution density given, convert the solution\u2019s volume to mass, and then use the given mass\npercentage to calculate the solute mass. This mathematical approach is outlined in this flowchart:\n"]], ["block_14", [{"image_0": "158_0.png", "coords": [72, 609, 504, 670]}]], ["block_15", ["For proper unit cancellation, the 0.500-L volume is converted into 500 mL, and the mass percentage is\nexpressed as a ratio, 37.2 g HCl/g solution:\n"]], ["block_16", ["EXAMPLE 3.22\n"]], ["block_17", ["EXAMPLE 3.23\n"]], ["block_18", [" 3.4 \u2022 Other Units for Solution Concentrations \n 145 \n"]]], "page_159": [["block_0", [" 146 \n 3 \u2022 Composition of Substances and Solutions \n"]], ["block_1", ["This mass of HCl is consistent with our rough estimate of approximately 200 g.\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["What volume of concentrated HCl solution contains 125 g of HCl?\n"]], ["block_4", [" Answer: \n282 mL\n"]], ["block_5", [" Volume Percentage \n"]], ["block_6", ["Liquid volumes over a wide range of magnitudes are conveniently measured using common and relatively\ninexpensive laboratory equipment. The concentration of a solution formed by dissolving a liquid solute in a\nliquid solvent is therefore often expressed as a volume percentage , %vol or (v/v)%:\n"]], ["block_7", [" Calculations using Volume Percentage \n"]], ["block_8", ["Rubbing alcohol (isopropanol) is usually sold as a 70%vol aqueous solution. If the density of isopropyl alcohol\nis 0.785 g/mL, how many grams of isopropyl alcohol are present in a 355 mL bottle of rubbing alcohol?\n"]], ["block_9", [" Solution \n"]], ["block_10", ["Per the definition of volume percentage, the isopropanol volume is 70% of the total solution volume.\nMultiplying the isopropanol volume by its density yields the requested mass:\n"]], ["block_11", [" Check Your Learning \n"]], ["block_12", ["Wine is approximately 12% ethanol (CH3CH2OH) by volume. Ethanol has a molar mass of 46.06 g/mol and a\ndensity 0.789 g/mL. How many moles of ethanol are present in a 750-mL bottle of wine?\n"]], ["block_13", [" Answer: \n1.5 mol ethanol\n"]], ["block_14", [" Mass-Volume Percentage \n"]], ["block_15", ["\u201cMixed\u201d percentage units, derived from the mass of solute and the volume of solution, are popular for certain\nbiochemical and medical applications. A mass-volume percent is a ratio of a solute\u2019s mass to the solution\u2019s\nvolume expressed as a percentage. The specific units used for solute mass and solution volume may vary,\ndepending on the solution. For example, physiological saline solution, used to prepare intravenous fluids, has\na concentration of 0.9% mass/volume (m/v), indicating that the composition is 0.9 g of solute per 100 mL of\nsolution. The concentration of glucose in blood (commonly referred to as \u201cblood sugar\u201d) is also typically\nexpressed in terms of a mass-volume ratio. Though not expressed explicitly as a percentage, its concentration\nis usually given in milligrams of glucose per deciliter (100 mL) of blood (Figure 3.18).\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["EXAMPLE 3.24\n"]]], "page_160": [["block_0", [{"image_0": "160_0.png", "coords": [72, 57, 540, 288]}]], ["block_1", [" FIGURE 3.18 \n\u201cMixed\u201d mass-volume units are commonly encountered in medical settings. (a) The NaCl\n"]], ["block_2", ["concentration of physiological saline is 0.9% (m/v). (b) This device measures glucose levels in a sample of blood.\nThe normal range for glucose concentration in blood (fasting) is around 70\u2013100 mg/dL. (credit a: modification of\nwork by \u201cThe National Guard\u201d/Flickr; credit b: modification of work by Biswarup Ganguly)\n"]], ["block_3", [" Parts per Million and Parts per Billion \n"]], ["block_4", ["Very low solute concentrations are often expressed using appropriately small units such as parts per million \n (ppm) or parts per billion (ppb) . Like percentage (\u201cpart per hundred\u201d) units, ppm and ppb may be defined in\nterms of masses, volumes, or mixed mass-volume units. There are also ppm and ppb units defined with\nrespect to numbers of atoms and molecules.\n"]], ["block_5", ["The mass-based definitions of ppm and ppb are given here:\n"]], ["block_6", ["Both ppm and ppb are convenient units for reporting the concentrations of pollutants and other trace\ncontaminants in water. Concentrations of these contaminants are typically very low in treated and natural\nwaters, and their levels cannot exceed relatively low concentration thresholds without causing adverse effects\non health and wildlife. For example, the EPA has identified the maximum safe level of fluoride ion in tap water\nto be 4 ppm. Inline water filters are designed to reduce the concentration of fluoride and several other trace-\nlevel contaminants in tap water (Figure 3.19).\n"]], ["block_7", [" 3.4 \u2022 Other Units for Solution Concentrations \n 147 \n"]]], "page_161": [["block_0", [" 148 \n 3 \u2022 Composition of Substances and Solutions \n"]], ["block_1", [{"image_0": "161_0.png", "coords": [72, 57, 540, 295]}]], ["block_2", [" FIGURE 3.19 \n(a) In some areas, trace-level concentrations of contaminants can render unfiltered tap water unsafe\n"]], ["block_3", ["for drinking and cooking. (b) Inline water filters reduce the concentration of solutes in tap water. (credit a:\nmodification of work by Jenn Durfey; credit b: modification of work by \u201cvastateparkstaff\u201d/Wikimedia commons)\n"]], ["block_4", [" Calculation of Parts per Million and Parts per Billion Concentrations \n"]], ["block_5", ["According to the EPA, when the concentration of lead in tap water reaches 15 ppb, certain remedial actions\nmust be taken. What is this concentration in ppm? At this concentration, what mass of lead (\u03bcg) would be\ncontained in a typical glass of water (300 mL)?\n"]], ["block_6", [" Solution \n"]], ["block_7", ["The definitions of the ppm and ppb units may be used to convert the given concentration from ppb to ppm.\nComparing these two unit definitions shows that ppm is 1000 times greater than ppb (1 ppm = 10ppb). Thus:\n"]], ["block_8", ["The definition of the ppb unit may be used to calculate the requested mass if the mass of the solution is\nprovided. Since the volume of solution (300 mL) is given, its density must be used to derive the corresponding\nmass. Assume the density of tap water to be roughly the same as that of pure water (~1.00 g/mL), since the\nconcentrations of any dissolved substances should not be very large. Rearranging the equation defining the\nppb unit and substituting the given quantities yields:\n"]], ["block_9", ["Finally, convert this mass to the requested unit of micrograms:\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["EXAMPLE 3.25\n"]]], "page_162": [["block_0", [" Check Your Learning \n"]], ["block_1", ["A 50.0-g sample of industrial wastewater was determined to contain 0.48 mg of mercury. Express the mercury\nconcentration of the wastewater in ppm and ppb units.\n"]], ["block_2", [" Answer: \n9.6 ppm, 9600 ppb\n"]], ["block_3", [" 3.4 \u2022 Other Units for Solution Concentrations \n 149 \n"]]], "page_163": [["block_0", [" 150 \n 3 \u2022 Key Terms \n"]], ["block_1", [" Key Terms \n"]], ["block_2", [" aqueous solution \nsolution for which water is the\n"]], ["block_3", [" Avogadro\u2019s number (N A ) \nexperimentally\n"]], ["block_4", [" concentrated \nqualitative term for a solution\n"]], ["block_5", [" concentration \nquantitative measure of the relative\n"]], ["block_6", [" dilute \nqualitative term for a solution containing\n"]], ["block_7", [" dilution \nprocess of adding solvent to a solution in\n"]], ["block_8", [" dissolved \ndescribes the process by which solute\n"]], ["block_9", [" empirical formula mass \nsum of average atomic\n"]], ["block_10", [" formula mass \nsum of the average masses for all\n"]], ["block_11", [" mass percentage \nratio of solute-to-solution mass\n"]], ["block_12", [" Key Equations \n"]], ["block_13", [" Summary \n"]], ["block_14", [" 3.1 Formula Mass and the Mole Concept \n"]], ["block_15", ["The formula mass of a substance is the sum of the\naverage atomic masses of each atom represented in\nthe chemical formula and is expressed in atomic\nmass units. The formula mass of a covalent\ncompound is also called the molecular mass. A\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["C1V1 = C2V2\n"]], ["block_18", ["(AxBy)n = AnxBny\n"]], ["block_19", [" solvent \n"]], ["block_20", ["determined value of the number of entities\ncomprising 1 mole of substance, equal to 6.022\n10mol\n"]], ["block_21", ["containing solute at a relatively high\n concentration \n"]], ["block_22", ["amounts of solute and solvent present in a\nsolution\n"]], ["block_23", ["solute at a relatively low concentration\n"]], ["block_24", ["order to lower the concentration of solutes\n"]], ["block_25", ["components are dispersed in a solvent\n"]], ["block_26", ["masses for all atoms represented in an empirical\nformula\n"]], ["block_27", ["atoms represented in a chemical formula; for\ncovalent compounds, this is also the molecular\nmass\n"]], ["block_28", [" mass-volume percent \nratio of solute mass to\n"]], ["block_29", [" molar mass \nmass in grams of 1 mole of a\n"]], ["block_30", [" molarity (M) \nunit of concentration, defined as the\n"]], ["block_31", [" mole \namount of substance containing the same\n"]], ["block_32", [" parts per billion (ppb) \nratio of solute-to-solution\n"]], ["block_33", [" parts per million (ppm) \nratio of solute-to-solution\n"]], ["block_34", [" percent composition \npercentage by mass of the\n"]], ["block_35", [" solute \nsolution component present in a\n"]], ["block_36", [" solvent \nsolution component present in a\n"]], ["block_37", [" volume percentage \nratio of solute-to-solution\n"]], ["block_38", ["convenient amount unit for expressing very large\nnumbers of atoms or molecules is the mole.\nExperimental measurements have determined the\nnumber of entities composing 1 mole of substance\nto be 6.022\n10, a quantity called Avogadro\u2019s\n"]], ["block_39", ["number. The mass in grams of 1 mole of substance\nis its molar mass. Due to the use of the same\n"]], ["block_40", ["expressed as a percentage\n"]], ["block_41", ["solution volume, expressed as a percentage\n"]], ["block_42", ["substance\n"]], ["block_43", ["number of moles of solute dissolved in 1 liter of\nsolution\n"]], ["block_44", ["number of atoms, molecules, ions, or other\nentities as the number of atoms in exactly 12\ngrams of C\n"]], ["block_45", ["mass multiplied by 10\n"]], ["block_46", ["mass multiplied by 10\n"]], ["block_47", ["various elements in a compound\n"]], ["block_48", ["concentration less than that of the solvent\n"]], ["block_49", ["concentration that is higher relative to other\ncomponents\n"]], ["block_50", ["volume expressed as a percentage\n"]]], "page_164": [["block_0", ["reference substance in defining the atomic mass\nunit and the mole, the formula mass (amu) and\nmolar mass (g/mol) for any substance are\nnumerically equivalent (for example, one H2O\nmolecule weighs approximately18 amu and 1 mole\nof H2O molecules weighs approximately 18 g).\n"]], ["block_1", [" 3.2 Determining Empirical and Molecular \n Formulas \n"]], ["block_2", ["The chemical identity of a substance is defined by\nthe types and relative numbers of atoms composing\nits fundamental entities (molecules in the case of\ncovalent compounds, ions in the case of ionic\ncompounds). A compound\u2019s percent composition\nprovides the mass percentage of each element in the\ncompound, and it is often experimentally\ndetermined and used to derive the compound\u2019s\nempirical formula. The empirical formula mass of a\ncovalent compound may be compared to the\ncompound\u2019s molecular or molar mass to derive a\nmolecular formula.\n"]], ["block_3", [" 3.3 Molarity \n"]], ["block_4", ["Solutions are homogeneous mixtures. Many\nsolutions contain one component, called the solvent,\n"]], ["block_5", [" Exercises \n"]], ["block_6", [" 3.1 Formula Mass and the Mole Concept \n"]], ["block_7", [" 1 . What is the total mass (amu) of carbon in each of the following molecules?\n"]], ["block_8", [" 2 . What is the total mass of hydrogen in each of the molecules?\n"]], ["block_9", [" 3 . Calculate the molecular or formula mass of each of the following:\n"]], ["block_10", ["(a) CH4\n(b) CHCl3\n(c) C12H10O6\n(d) CH3CH2CH2CH2CH3\n"]], ["block_11", ["(a) CH4\n(b) CHCl3\n(c) C12H10O6\n(d) CH3CH2CH2CH2CH3\n"]], ["block_12", ["(a) P4\n(b) H2O\n(c) Ca(NO3)2\n(d) CH3CO2H (acetic acid)\n(e) C12H22O11 (sucrose, cane sugar)\n"]], ["block_13", ["in which other components, called solutes, are\ndissolved. An aqueous solution is one for which the\nsolvent is water. The concentration of a solution is a\nmeasure of the relative amount of solute in a given\namount of solution. Concentrations may be\nmeasured using various units, with one very useful\nunit being molarity, defined as the number of moles\nof solute per liter of solution. The solute\nconcentration of a solution may be decreased by\nadding solvent, a process referred to as dilution. The\ndilution equation is a simple relation between\nconcentrations and volumes of a solution before and\nafter dilution.\n"]], ["block_14", [" 3.4 Other Units for Solution Concentrations \n"]], ["block_15", ["In addition to molarity, a number of other solution\nconcentration units are used in various applications.\nPercentage concentrations based on the solution\ncomponents\u2019 masses, volumes, or both are useful for\nexpressing relatively high concentrations, whereas\nlower concentrations are conveniently expressed\nusing ppm or ppb units. These units are popular in\nenvironmental, medical, and other fields where\nmole-based units such as molarity are not as\ncommonly used.\n"]], ["block_16", [" 3 \u2022 Exercises \n 151 \n"]]], "page_165": [["block_0", [" 152 \n 3 \u2022 Exercises \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" 4 . Determine the molecular mass of the following compounds:\n"]], ["block_3", [" 5 . Determine the molecular mass of the following compounds:\n"]], ["block_4", [" 6 . Which molecule has a molecular mass of 28.05 amu?\n"]], ["block_5", [" 7 . Write a sentence that describes how to determine the number of moles of a compound in a known mass of\n"]], ["block_6", ["(a)\n"]], ["block_7", [{"image_0": "165_0.png", "coords": [89, 82, 206, 127]}]], ["block_8", ["(b)\n"]], ["block_9", [{"image_1": "165_1.png", "coords": [89, 143, 206, 154]}]], ["block_10", ["(c)\n"]], ["block_11", [{"image_2": "165_2.png", "coords": [89, 170, 206, 212]}]], ["block_12", ["(d)\n"]], ["block_13", [{"image_3": "165_3.png", "coords": [89, 227, 206, 276]}]], ["block_14", ["(a)\n"]], ["block_15", [{"image_4": "165_4.png", "coords": [89, 304, 206, 348]}]], ["block_16", ["(b)\n"]], ["block_17", [{"image_5": "165_5.png", "coords": [89, 364, 206, 412]}]], ["block_18", ["(c)\n"]], ["block_19", [{"image_6": "165_6.png", "coords": [89, 427, 206, 476]}]], ["block_20", ["(d)\n"]], ["block_21", [{"image_7": "165_7.png", "coords": [89, 491, 206, 540]}]], ["block_22", ["(a)\n"]], ["block_23", [{"image_8": "165_8.png", "coords": [89, 568, 206, 581]}]], ["block_24", ["(b)\n"]], ["block_25", [{"image_9": "165_9.png", "coords": [89, 596, 206, 639]}]], ["block_26", ["(c)\n"]], ["block_27", [{"image_10": "165_10.png", "coords": [89, 654, 206, 702]}]], ["block_28", ["the compound using its molecular formula.\n"]]], "page_166": [["block_0", [" 10 . Which contains the greatest number of moles of oxygen atoms: 1 mol of ethanol (C2H5OH), 1 mol of formic\n"]], ["block_1", [" 11 . How are the molecular mass and the molar mass of a compound similar and how are they different?\n 12 . Calculate the molar mass of each of the following compounds:\n"]], ["block_2", [" 13 . Calculate the molar mass of each of the following:\n"]], ["block_3", [" 14 . Calculate the empirical or molecular formula mass and the molar mass of each of the following minerals:\n"]], ["block_4", [" 15 . Calculate the molar mass of each of the following:\n"]], ["block_5", [" 16 . Determine the number of moles of compound and the number of moles of each type of atom in each of the\n"]], ["block_6", [" 17 . Determine the mass of each of the following:\n"]], ["block_7", [" 18 . Determine the number of moles of the compound and determine the number of moles of each type of\n"]], ["block_8", [" 8 . Compare 1 mole of H2, 1 mole of O2, and 1 mole of F2.\n"]], ["block_9", [" 9 . Which contains the greatest mass of oxygen: 0.75 mol of ethanol (C2H5OH), 0.60 mol of formic acid\n"]], ["block_10", ["(a) Which has the largest number of molecules? Explain why.\n(b) Which has the greatest mass? Explain why.\n"]], ["block_11", ["(HCO2H), or 1.0 mol of water (H2O)? Explain why.\n"]], ["block_12", ["acid (HCO2H), or 1 mol of water (H2O)? Explain why.\n"]], ["block_13", ["(a) hydrogen fluoride, HF\n(b) ammonia, NH3\n(c) nitric acid, HNO3\n(d) silver sulfate, Ag2SO4\n(e) boric acid, B(OH)3\n"]], ["block_14", ["(a) S8\n(b) C5H12\n(c) Sc2(SO4)3\n(d) CH3COCH3 (acetone)\n(e) C6H12O6 (glucose)\n"]], ["block_15", ["(a) limestone, CaCO3\n(b) halite, NaCl\n(c) beryl, Be3Al2Si6O18\n(d) malachite, Cu2(OH)2CO3\n(e) turquoise, CuAl6(PO4)4(OH)8(H2O)4\n"]], ["block_16", ["(a) the anesthetic halothane, C2HBrClF3\n(b) the herbicide paraquat, C12H14N2Cl2\n(c) caffeine, C8H10N4O2\n(d) urea, CO(NH2)2\n(e) a typical soap, C17H35CO2Na\n"]], ["block_17", ["following:\n(a) 25.0 g of propylene, C3H6\n(b) 3.06\n10g of the amino acid glycine, C2H5NO2\n"]], ["block_18", ["(c) 25 lb of the herbicide Treflan, C13H16N2O4F (1 lb = 454 g)\n(d) 0.125 kg of the insecticide Paris Green, Cu4(AsO3)2(CH3CO2)2\n(e) 325 mg of aspirin, C6H4(CO2H)(CO2CH3)\n"]], ["block_19", ["(a) 0.0146 mol KOH\n(b) 10.2 mol ethane, C2H6\n(c) 1.6\n10mol Na2 SO4\n"]], ["block_20", ["(d) 6.854\n10mol glucose, C6 H12 O6\n"]], ["block_21", ["(e) 2.86 mol Co(NH3)6Cl3\n"]], ["block_22", ["atom in each of the following:\n(a) 2.12 g of potassium bromide, KBr\n(b) 0.1488 g of phosphoric acid, H3PO4\n(c) 23 kg of calcium carbonate, CaCO3\n(d) 78.452 g of aluminum sulfate, Al2(SO4)3\n(e) 0.1250 mg of caffeine, C8H10N4O2\n"]], ["block_23", [" 3 \u2022 Exercises \n 153 \n"]]], "page_167": [["block_0", [" 154 \n 3 \u2022 Exercises \n"]], ["block_1", [" 19 . Determine the mass of each of the following:\n"]], ["block_2", [" 20 . The approximate minimum daily dietary requirement of the amino acid leucine, C6H13NO2, is 1.1 g. What\n"]], ["block_3", [" 21 . Determine the mass in grams of each of the following:\n"]], ["block_4", [" 22 . A 55-kg woman has 7.5\n10mol of hemoglobin (molar mass = 64,456 g/mol) in her blood. How many\n"]], ["block_5", [" 23 . Determine the number of atoms and the mass of zirconium, silicon, and oxygen found in 0.3384 mol of\n"]], ["block_6", [" 24 . Determine which of the following contains the greatest mass of hydrogen: 1 mol of CH4, 0.6 mol of C6H6, or\n"]], ["block_7", [" 25 . Determine which of the following contains the greatest mass of aluminum: 122 g of AlPO4, 266 g of Al2Cl6,\n"]], ["block_8", [" 26 . Diamond is one form of elemental carbon. An engagement ring contains a diamond weighing 1.25 carats\n"]], ["block_9", [" 27 . The Cullinan diamond was the largest natural diamond ever found (January 25, 1905). It weighed 3104\n"]], ["block_10", [" 28 . One 55-gram serving of a particular cereal supplies 270 mg of sodium, 11% of the recommended daily\n"]], ["block_11", [" 29 . A certain nut crunch cereal contains 11.0 grams of sugar (sucrose, C12H22O11) per serving size of 60.0\n"]], ["block_12", [" 30 . A tube of toothpaste contains 0.76 g of sodium monofluorophosphate (Na2PO3F) in 100 mL.\n"]], ["block_13", [" 31 . Which of the following represents the least number of molecules?\n"]], ["block_14", [" 3.2 Determining Empirical and Molecular Formulas \n"]], ["block_15", [" 32 . What information is needed to determine the molecular formula of a compound from the empirical\n"]], ["block_16", [" 33 . Calculate the following to four significant figures:\n"]], ["block_17", [" 34 . Determine the following to four significant figures:\n"]], ["block_18", [" 35 . Determine the percent ammonia, NH3, in Co(NH3)6Cl3, to three significant figures.\n 36 . Determine the percent water in CuSO4\u22195H2O to three significant figures.\n"]], ["block_19", [" Access for free at openstax.org \n"]], ["block_20", ["(a) 2.345 mol LiCl\n(b) 0.0872 mol acetylene, C2H2\n(c) 3.3\n10mol Na2 CO3\n"]], ["block_21", ["(d) 1.23\n10mol fructose, C6 H12 O6\n"]], ["block_22", ["(e) 0.5758 mol FeSO4(H2O)7\n"]], ["block_23", ["is this requirement in moles?\n"]], ["block_24", ["(a) 0.600 mol of oxygen atoms\n(b) 0.600 mol of oxygen molecules, O2\n(c) 0.600 mol of ozone molecules, O3\n"]], ["block_25", ["hemoglobin molecules is this? What is this quantity in grams?\n"]], ["block_26", ["zircon, ZrSiO4, a semiprecious stone.\n"]], ["block_27", ["0.4 mol of C3H8.\n"]], ["block_28", ["or 225 g of Al2S3.\n"]], ["block_29", ["(1 carat = 200 mg). How many atoms are present in the diamond?\n"]], ["block_30", ["carats (1 carat = 200 mg). How many carbon atoms were present in the stone?\n"]], ["block_31", ["allowance. How many moles and atoms of sodium are in the recommended daily allowance?\n"]], ["block_32", ["grams. How many servings of this cereal must be eaten to consume 0.0278 moles of sugar?\n"]], ["block_33", ["(a) What mass of fluorine atoms in mg was present?\n(b) How many fluorine atoms were present?\n"]], ["block_34", ["(a) 20.0 g of H2O (18.02 g/mol)\n(b) 77.0 g of CH4 (16.06 g/mol)\n(c) 68.0 g of C3H6 (42.08 g/mol)\n(d) 100.0 g of N2O (44.02 g/mol)\n(e) 84.0 g of HF (20.01 g/mol)\n"]], ["block_35", ["formula?\n"]], ["block_36", ["(a) the percent composition of ammonia, NH3\n(b) the percent composition of photographic fixer solution (\u201chypo\u201d), Na2S2O3\n(c) the percent of calcium ion in Ca3(PO4)2\n"]], ["block_37", ["(a) the percent composition of hydrazoic acid, HN3\n(b) the percent composition of TNT, C6H2(CH3)(NO2)3\n(c) the percent of SO4in Al2(SO4)3\n"]]], "page_168": [["block_0", [" 37 . Determine the empirical formulas for compounds with the following percent compositions:\n"]], ["block_1", [" 38 . Determine the empirical formulas for compounds with the following percent compositions:\n"]], ["block_2", [" 39 . A compound of carbon and hydrogen contains 92.3% C and has a molar mass of 78.1 g/mol. What is its\n"]], ["block_3", [" 40 . Dichloroethane, a compound that is often used for dry cleaning, contains carbon, hydrogen, and chlorine.\n"]], ["block_4", [" 41 . Determine the empirical and molecular formula for chrysotile asbestos. Chrysotile has the following\n"]], ["block_5", [" 42 . Polymers are large molecules composed of simple units repeated many times. Thus, they often have\n"]], ["block_6", [" 43 . A major textile dye manufacturer developed a new yellow dye. The dye has a percent composition of\n"]], ["block_7", [" 3.3 Molarity \n"]], ["block_8", [" 44 . Explain what changes and what stays the same when 1.00 L of a solution of NaCl is diluted to 1.80 L.\n 45 . What information is needed to calculate the molarity of a sulfuric acid solution?\n 46 . A 200-mL sample and a 400-mL sample of a solution of salt have the same molarity. In what ways are the\n"]], ["block_9", [" 47 . Determine the molarity for each of the following solutions:\n"]], ["block_10", [" 48 . Determine the molarity of each of the following solutions:\n"]], ["block_11", [" 49 . Consider this question: What is the mass of the solute in 0.500 L of 0.30 M glucose, C6H12O6, used for\n"]], ["block_12", [" 50 . Consider this question: What is the mass of solute in 200.0 L of a 1.556-M solution of KBr?\n"]], ["block_13", ["(a) 15.8% carbon and 84.2% sulfur\n(b) 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen\n"]], ["block_14", ["(a) 43.6% phosphorus and 56.4% oxygen\n(b) 28.7% K, 1.5% H, 22.8% P, and 47.0% O\n"]], ["block_15", ["molecular formula?\n"]], ["block_16", ["It has a molar mass of 99 g/mol. Analysis of a sample shows that it contains 24.3% carbon and 4.1%\nhydrogen. What is its molecular formula?\n"]], ["block_17", ["percent composition: 28.03% Mg, 21.60% Si, 1.16% H, and 49.21% O. The molar mass for chrysotile is\n520.8 g/mol.\n"]], ["block_18", ["relatively simple empirical formulas. Calculate the empirical formulas of the following polymers:\n(a) Lucite (Plexiglas); 59.9% C, 8.06% H, 32.0% O\n(b) Saran; 24.8% C, 2.0% H, 73.1% Cl\n(c) polyethylene; 86% C, 14% H\n(d) polystyrene; 92.3% C, 7.7% H\n(e) Orlon; 67.9% C, 5.70% H, 26.4% N\n"]], ["block_19", ["75.95% C, 17.72% N, and 6.33% H by mass with a molar mass of about 240 g/mol. Determine the\nmolecular formula of the dye.\n"]], ["block_20", ["two samples identical? In what ways are these two samples different?\n"]], ["block_21", ["(a) 0.444 mol of CoCl2 in 0.654 L of solution\n(b) 98.0 g of phosphoric acid, H3PO4, in 1.00 L of solution\n(c) 0.2074 g of calcium hydroxide, Ca(OH)2, in 40.00 mL of solution\n(d) 10.5 kg of Na2SO4\u00b710H2O in 18.60 L of solution\n(e) 7.0\n10mol of I2 in 100.0 mL of solution\n"]], ["block_22", ["(f) 1.8\n10mg of HCl in 0.075 L of solution\n"]], ["block_23", ["(a) 1.457 mol KCl in 1.500 L of solution\n(b) 0.515 g of H2SO4 in 1.00 L of solution\n(c) 20.54 g of Al(NO3)3 in 1575 mL of solution\n(d) 2.76 kg of CuSO4\u00b75H2O in 1.45 L of solution\n(e) 0.005653 mol of Br2 in 10.00 mL of solution\n(f) 0.000889 g of glycine, C2H5NO2, in 1.05 mL of solution\n"]], ["block_24", ["intravenous injection?\n(a) Outline the steps necessary to answer the question.\n(b) Answer the question.\n"]], ["block_25", ["(a) Outline the steps necessary to answer the question.\n(b) Answer the question.\n"]], ["block_26", [" 3 \u2022 Exercises \n 155 \n"]]], "page_169": [["block_0", [" 156 \n 3 \u2022 Exercises \n"]], ["block_1", [" 51 . Calculate the number of moles and the mass of the solute in each of the following solutions:\n"]], ["block_2", [" 52 . Calculate the number of moles and the mass of the solute in each of the following solutions:\n"]], ["block_3", [" 53 . Consider this question: What is the molarity of KMnO4 in a solution of 0.0908 g of KMnO4 in 0.500 L of\n"]], ["block_4", [" 54 . Consider this question: What is the molarity of HCl if 35.23 mL of a solution of HCl contain 0.3366 g of\n"]], ["block_5", [" 55 . Calculate the molarity of each of the following solutions:\n"]], ["block_6", [" 56 . Calculate the molarity of each of the following solutions:\n"]], ["block_7", [" 57 . There is about 1.0 g of calcium, as Ca, in 1.0 L of milk. What is the molarity of Cain milk?\n 58 . What volume of a 1.00-M Fe(NO3)3 solution can be diluted to prepare 1.00 L of a solution with a\n"]], ["block_8", [" 59 . If 0.1718 L of a 0.3556-M C3H7OH solution is diluted to a concentration of 0.1222 M, what is the volume of\n"]], ["block_9", [" 60 . If 4.12 L of a 0.850 M-H3PO4 solution is be diluted to a volume of 10.00 L, what is the concentration of the\n"]], ["block_10", [" 61 . What volume of a 0.33-M C12H22O11 solution can be diluted to prepare 25 mL of a solution with a\n"]], ["block_11", [" 62 . What is the concentration of the NaCl solution that results when 0.150 L of a 0.556-M solution is allowed to\n"]], ["block_12", [" 63 . What is the molarity of the diluted solution when each of the following solutions is diluted to the given\n"]], ["block_13", [" 64 . What is the final concentration of the solution produced when 225.5 mL of a 0.09988-M solution of\n"]], ["block_14", [" 65 . A 2.00-L bottle of a solution of concentrated HCl was purchased for the general chemistry laboratory. The\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["(a) 2.00 L of 18.5 M H2SO4, concentrated sulfuric acid\n(b) 100.0 mL of 3.8\n10M NaCN, the minimum lethal concentration of sodium cyanide in blood serum\n"]], ["block_17", ["(c) 5.50 L of 13.3 M H2CO, the formaldehyde used to \u201cfix\u201d tissue samples\n(d) 325 mL of 1.8\n10M FeSO4, the minimum concentration of iron sulfate detectable by taste in\n"]], ["block_18", ["drinking water\n"]], ["block_19", ["(a) 325 mL of 8.23\n10M KI, a source of iodine in the diet\n"]], ["block_20", ["(b) 75.0 mL of 2.2\n10M H2SO4, a sample of acid rain\n"]], ["block_21", ["(c) 0.2500 L of 0.1135 M K2CrO4, an analytical reagent used in iron assays\n(d) 10.5 L of 3.716 M (NH4)2SO4, a liquid fertilizer\n"]], ["block_22", ["solution?\n(a) Outline the steps necessary to answer the question.\n(b) Answer the question.\n"]], ["block_23", ["HCl?\n(a) Outline the steps necessary to answer the question.\n(b) Answer the question.\n"]], ["block_24", ["(a) 0.195 g of cholesterol, C27H46O, in 0.100 L of serum, the average concentration of cholesterol in human\nserum\n(b) 4.25 g of NH3 in 0.500 L of solution, the concentration of NH3 in household ammonia\n(c) 1.49 kg of isopropyl alcohol, C3H7OH, in 2.50 L of solution, the concentration of isopropyl alcohol in\nrubbing alcohol\n(d) 0.029 g of I2 in 0.100 L of solution, the solubility of I2 in water at 20 \u00b0C\n"]], ["block_25", ["(a) 293 g HCl in 666 mL of solution, a concentrated HCl solution\n(b) 2.026 g FeCl3 in 0.1250 L of a solution used as an unknown in general chemistry laboratories\n(c) 0.001 mg Cdin 0.100 L, the maximum permissible concentration of cadmium in drinking water\n(d) 0.0079 g C7H5SNO3 in one ounce (29.6 mL), the concentration of saccharin in a diet soft drink.\n"]], ["block_26", ["concentration of 0.250 M?\n"]], ["block_27", ["the resulting solution?\n"]], ["block_28", ["resulting solution?\n"]], ["block_29", ["concentration of 0.025 M?\n"]], ["block_30", ["evaporate until the volume is reduced to 0.105 L?\n"]], ["block_31", ["final volume?\n(a) 1.00 L of a 0.250-M solution of Fe(NO3)3 is diluted to a final volume of 2.00 L\n(b) 0.5000 L of a 0.1222-M solution of C3H7OH is diluted to a final volume of 1.250 L\n(c) 2.35 L of a 0.350-M solution of H3PO4 is diluted to a final volume of 4.00 L\n(d) 22.50 mL of a 0.025-M solution of C12H22O11 is diluted to 100.0 mL\n"]], ["block_32", ["Na2CO3 is allowed to evaporate until the solution volume is reduced to 45.00 mL?\n"]], ["block_33", ["solution contained 868.8 g of HCl. What is the molarity of the solution?\n"]]], "page_170": [["block_0", [" 66 . An experiment in a general chemistry laboratory calls for a 2.00-M solution of HCl. How many mL of 11.9\n"]], ["block_1", [" 67 . What volume of a 0.20-M K2SO4 solution contains 57 g of K2SO4?\n 68 . The US Environmental Protection Agency (EPA) places limits on the quantities of toxic substances that\n"]], ["block_2", [" 3.4 Other Units for Solution Concentrations \n"]], ["block_3", [" 69 . Consider this question: What mass of a concentrated solution of nitric acid (68.0% HNO3 by mass) is\n"]], ["block_4", [" 70 . What mass of a 4.00% NaOH solution by mass contains 15.0 g of NaOH?\n 71 . What mass of solid NaOH (97.0% NaOH by mass) is required to prepare 1.00 L of a 10.0% solution of\n"]], ["block_5", [" 72 . What mass of HCl is contained in 45.0 mL of an aqueous HCl solution that has a density of 1.19 g cmand\n"]], ["block_6", [" 73 . The hardness of water (hardness count) is usually expressed in parts per million (by mass) of CaCO3,\n"]], ["block_7", [" 74 . The level of mercury in a stream was suspected to be above the minimum considered safe (1 part per\n"]], ["block_8", [" 75 . In Canada and the United Kingdom, devices that measure blood glucose levels provide a reading in\n"]], ["block_9", [" 76 . A throat spray is 1.40% by mass phenol, C6H5OH, in water. If the solution has a density of 0.9956 g/mL,\n"]], ["block_10", [" 77 . Copper(I) iodide (CuI) is often added to table salt as a dietary source of iodine. How many moles of CuI are\n"]], ["block_11", [" 78 . A cough syrup contains 5.0% ethyl alcohol, C2H5OH, by mass. If the density of the solution is 0.9928 g/mL,\n"]], ["block_12", [" 79 . D5W is a solution used as an intravenous fluid. It is a 5.0% by mass solution of dextrose (C6H12O6) in\n"]], ["block_13", [" 80 . Find the molarity of a 40.0% by mass aqueous solution of sulfuric acid, H2SO4, for which the density is\n"]], ["block_14", ["M HCl would be required to make 250 mL of 2.00 M HCl?\n"]], ["block_15", ["may be discharged into the sewer system. Limits have been established for a variety of substances,\nincluding hexavalent chromium, which is limited to 0.50 mg/L. If an industry is discharging hexavalent\nchromium as potassium dichromate (K2Cr2O7), what is the maximum permissible molarity of that\nsubstance?\n"]], ["block_16", ["needed to prepare 400.0 g of a 10.0% solution of HNO3 by mass?\n(a) Outline the steps necessary to answer the question.\n(b) Answer the question.\n"]], ["block_17", ["NaOH by mass? The density of the 10.0% solution is 1.109 g/mL.\n"]], ["block_18", ["contains 37.21% HCl by mass?\n"]], ["block_19", ["which is equivalent to milligrams of CaCO3 per liter of water. What is the molar concentration of Caions\nin a water sample with a hardness count of 175 mg CaCO3/L?\n"]], ["block_20", ["billion by weight). An analysis indicated that the concentration was 0.68 parts per billion. Assume a\ndensity of 1.0 g/mL and calculate the molarity of mercury in the stream.\n"]], ["block_21", ["millimoles per liter. If a measurement of 5.3 mM is observed, what is the concentration of glucose\n(C6H12O6) in mg/dL?\n"]], ["block_22", ["calculate the molarity of the solution.\n"]], ["block_23", ["contained in 1.00 lb (454 g) of table salt containing 0.0100% CuI by mass?\n"]], ["block_24", ["determine the molarity of the alcohol in the cough syrup.\n"]], ["block_25", ["water. If the density of D5W is 1.029 g/mL, calculate the molarity of dextrose in the solution.\n"]], ["block_26", ["1.3057 g/mL.\n"]], ["block_27", [" 3 \u2022 Exercises \n 157 \n"]]], "page_171": [["block_0", [" 158 \n 3 \u2022 Exercises \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_172": [["block_0", ["the new Space Launch System being developed by the National Aeronautics and Space Administration (NASA)\nto replace the retired Space Shuttle fleet (Figure 4.1). The engines of these rockets rely on carefully prepared\nsolid mixtures of chemicals combined in precisely measured amounts. Igniting the mixture initiates a\nvigorous chemical reaction that rapidly generates large amounts of gaseous products. These gases are ejected\nfrom the rocket engine through its nozzle, providing the thrust needed to propel heavy payloads into space.\nBoth the nature of this chemical reaction and the relationships between the amounts of the substances being\nconsumed and produced by the reaction are critically important considerations that determine the success of\nthe technology. This chapter will describe how to symbolize chemical reactions using chemical equations, how\nto classify some common chemical reactions by identifying patterns of reactivity, and how to determine the\nquantitative relations between the amounts of substances involved in chemical reactions\u2014that is, the reaction\nstoichiometry.\n"]], ["block_1", ["CHAPTER 4\nStoichiometry of Chemical Reactions\n"]], ["block_2", [{"image_0": "172_0.png", "coords": [72, 104, 622, 376]}]], ["block_3", [" Figure 4.1 \nMany modern rocket fuels are solid mixtures of substances combined in carefully measured amounts\n"]], ["block_4", ["and ignited to yield a thrust-generating chemical reaction. (credit: modification of work by NASA)\n"]], ["block_5", [" CHAPTER OUTLINE \n"]], ["block_6", [" 4.1 Writing and Balancing Chemical Equations \n 4.2 Classifying Chemical Reactions \n 4.3 Reaction Stoichiometry \n 4.4 Reaction Yields \n 4.5 Quantitative Chemical Analysis \n"]], ["block_7", [" INTRODUCTION \n"]], ["block_8", ["Solid-fuel rockets are a central feature in the world\u2019s space exploration programs, including\n"]]], "page_173": [["block_0", [" 160 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", [" 4.1 Writing and Balancing Chemical Equations \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["An earlier chapter of this text introduced the use of element symbols to represent individual atoms. When\natoms gain or lose electrons to yield ions, or combine with other atoms to form molecules, their symbols are\nmodified or combined to generate chemical formulas that appropriately represent these species. Extending\nthis symbolism to represent both the identities and the relative quantities of substances undergoing a\nchemical (or physical) change involves writing and balancing a chemical equation . Consider as an example\nthe reaction between one methane molecule (CH4) and two diatomic oxygen molecules (O2) to produce one\ncarbon dioxide molecule (CO2) and two water molecules (H2O). The chemical equation representing this\nprocess is provided in the upper half of Figure 4.2, with space-filling molecular models shown in the lower half\nof the figure.\n"]], ["block_4", [" FIGURE 4.2 \nThe reaction between methane and oxygen to yield carbon dioxide and water (shown at bottom) may\n"]], ["block_5", ["be represented by a chemical equation using formulas (top).\n"]], ["block_6", ["This example illustrates the fundamental aspects of any chemical equation:\n"]], ["block_7", ["It is common practice to use the smallest possible whole-number coefficients in a chemical equation, as is\ndone in this example. Realize, however, that these coefficients represent the relative numbers of reactants and\nproducts, and, therefore, they may be correctly interpreted as ratios. Methane and oxygen react to yield carbon\ndioxide and water in a 1:2:1:2 ratio. This ratio is satisfied if the numbers of these molecules are, respectively,\n1-2-1-2, or 2-4-2-4, or 3-6-3-6, and so on (Figure 4.3). Likewise, these coefficients may be interpreted with\nregard to any amount (number) unit, and so this equation may be correctly read in many ways, including:\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["1.\nThe substances undergoing reaction are called reactants , and their formulas are placed on the left side of\nthe equation.\n"]], ["block_10", ["2.\nThe substances generated by the reaction are called products , and their formulas are placed on the right\nside of the equation.\n"]], ["block_11", ["3.\nPlus signs (+) separate individual reactant and product formulas, and an arrow\nseparates the\n"]], ["block_12", ["4.\nThe relative numbers of reactant and product species are represented by coefficients (numbers placed\nimmediately to the left of each formula). A coefficient of 1 is typically omitted.\n"]], ["block_13", ["\u2022\nOne methane molecule and two oxygen molecules react to yield one carbon dioxide molecule and two\nwater molecules.\n"]], ["block_14", ["\u2022\nOne dozen methane molecules and two dozen oxygen molecules react to yield one dozen carbon dioxide\nmolecules and two dozen water molecules.\n"]], ["block_15", ["\u2022\nOne mole of methane molecules and 2 moles of oxygen molecules react to yield 1 mole of carbon dioxide\n"]], ["block_16", ["\u2022\nDerive chemical equations from narrative descriptions of chemical reactions.\n"]], ["block_17", ["\u2022\nWrite and balance chemical equations in molecular, total ionic, and net ionic formats.\n"]], ["block_18", ["reactant and product (left and right) sides of the equation.\n"]], ["block_19", [{"image_0": "173_0.png", "coords": [130, 257, 481, 417]}]]], "page_174": [["block_0", [{"image_0": "174_0.png", "coords": [72, 76, 540, 257]}]], ["block_1", [" FIGURE 4.3 \nRegardless of the absolute numbers of molecules involved, the ratios between numbers of molecules\n"]], ["block_2", ["of each species that react (the reactants) and molecules of each species that form (the products) are the same and\nare given by the chemical reaction equation.\n"]], ["block_3", [" Balancing Equations \n"]], ["block_4", ["The chemical equation described in section 4.1 is balanced , meaning that equal numbers of atoms for each\nelement involved in the reaction are represented on the reactant and product sides. This is a requirement the\nequation must satisfy to be consistent with the law of conservation of matter. It may be confirmed by simply\nsumming the numbers of atoms on either side of the arrow and comparing these sums to ensure they are\nequal. Note that the number of atoms for a given element is calculated by multiplying the coefficient of any\nformula containing that element by the element\u2019s subscript in the formula. If an element appears in more than\none formula on a given side of the equation, the number of atoms represented in each must be computed and\nthen added together. For example, both product species in the example reaction, CO2 and H2O, contain the\nelement oxygen, and so the number of oxygen atoms on the product side of the equation is\n"]], ["block_5", ["The equation for the reaction between methane and oxygen to yield carbon dioxide and water is confirmed to\nbe balanced per this approach, as shown here:\n"]], ["block_6", ["A balanced chemical equation often may be derived from a qualitative description of some chemical reaction\nby a fairly simple approach known as balancing by inspection. Consider as an example the decomposition of\nwater to yield molecular hydrogen and oxygen. This process is represented qualitatively by an unbalanced\nchemical equation:\n"]], ["block_7", ["Comparing the number of H and O atoms on either side of this equation confirms its imbalance:\n"]], ["block_8", ["molecules and 2 moles of water molecules.\n"]], ["block_9", [" Element \n Reactants \n Products \n Balanced? \n"]], ["block_10", ["C\n1\n1 = 1\n1\n1 = 1\n1 = 1, yes\n"]], ["block_11", ["H\n4\n1 = 4\n2\n2 = 4\n4 = 4, yes\n"]], ["block_12", ["O\n2\n2 = 4\n(1\n2) + (2\n1) = 4\n4 = 4, yes\n"]], ["block_13", [" 4.1 \u2022 Writing and Balancing Chemical Equations \n 161 \n"]]], "page_175": [["block_0", [" 162 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", ["The numbers of H atoms on the reactant and product sides of the equation are equal, but the numbers of O\natoms are not. To achieve balance, the coefficients of the equation may be changed as needed. Keep in mind, of\ncourse, that the formula subscripts define, in part, the identity of the substance, and so these cannot be\nchanged without altering the qualitative meaning of the equation. For example, changing the reactant formula\nfrom H2O to H2O2 would yield balance in the number of atoms, but doing so also changes the reactant\u2019s\nidentity (it\u2019s now hydrogen peroxide and not water). The O atom balance may be achieved by changing the\ncoefficient for H2O to 2.\n"]], ["block_2", ["The H atom balance was upset by this change, but it is easily reestablished by changing the coefficient for the\nH2 product to 2.\n"]], ["block_3", ["These coefficients yield equal numbers of both H and O atoms on the reactant and product sides, and the\nbalanced equation is, therefore:\n"]], ["block_4", [" Balancing Chemical Equations \n"]], ["block_5", ["Write a balanced equation for the reaction of molecular nitrogen (N2) and oxygen (O2) to form dinitrogen\npentoxide.\n"]], ["block_6", [" Solution \n"]], ["block_7", ["First, write the unbalanced equation.\n"]], ["block_8", ["Next, count the number of each type of atom present in the unbalanced equation.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["EXAMPLE 4.1\n"]], ["block_11", [" Element \n Reactants \n Products \n Balanced? \n"]], ["block_12", ["H\n1\n2 = 2\n1\n2 = 2\n2 = 2, yes\n"]], ["block_13", ["O\n1\n1 = 1\n1\n2 = 2\n1 \u2260 2, no\n"]], ["block_14", [" Element \n Reactants \n Products \n Balanced? \n"]], ["block_15", ["H\n2\n2 = 4\n1\n2 = 2\n4 \u2260 2, no\n"]], ["block_16", ["O\n2\n1 = 2\n1\n2 = 2\n2 = 2, yes\n"]], ["block_17", [" Element \n Reactants \n Products \n Balanced? \n"]], ["block_18", ["H\n2\n2 = 4\n2\n2 = 4\n4 = 4, yes\n"]], ["block_19", ["O\n2\n1 = 2\n1\n2 = 2\n2 = 2, yes\n"]]], "page_176": [["block_0", ["Though nitrogen is balanced, changes in coefficients are needed to balance the number of oxygen atoms. To\nbalance the number of oxygen atoms, a reasonable first attempt would be to change the coefficients for the O2\nand N2O5 to integers that will yield 10 O atoms (the least common multiple for the O atom subscripts in these\ntwo formulas).\n"]], ["block_1", ["The N atom balance has been upset by this change; it is restored by changing the coefficient for the reactant N2\nto 2.\n"]], ["block_2", ["The numbers of N and O atoms on either side of the equation are now equal, and so the equation is balanced.\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["Write a balanced equation for the decomposition of ammonium nitrate to form molecular nitrogen, molecular\noxygen, and water. (Hint: Balance oxygen last, since it is present in more than one molecule on the right side of\nthe equation.)\n"]], ["block_5", [" Answer: \n"]], ["block_6", ["It is sometimes convenient to use fractions instead of integers as intermediate coefficients in the process of\nbalancing a chemical equation. When balance is achieved, all the equation\u2019s coefficients may then be\nmultiplied by a whole number to convert the fractional coefficients to integers without upsetting the atom\nbalance. For example, consider the reaction of ethane (C2H6) with oxygen to yield H2O and CO2, represented by\nthe unbalanced equation:\n"]], ["block_7", ["Following the usual inspection approach, one might first balance C and H atoms by changing the coefficients\nfor the two product species, as shown:\n"]], ["block_8", ["This results in seven O atoms on the product side of the equation, an odd number\u2014no integer coefficient can\nbe used with the O2 reactant to yield an odd number, so a fractional coefficient,\nis used instead to yield a\n"]], ["block_9", [" Element \n Reactants \n Products \n Balanced? \n"]], ["block_10", ["N\n1\n2 = 2\n2\n2 = 4\n2 \u2260 4, no\n"]], ["block_11", ["O\n5\n2 = 10\n2\n5 = 10\n10 = 10, yes\n"]], ["block_12", [" Element \n Reactants \n Products \n Balanced? \n"]], ["block_13", ["N\n2\n2 = 4\n2\n2 = 4\n4 = 4, yes\n"]], ["block_14", ["O\n5\n2 = 10\n2\n5 = 10\n10 = 10, yes\n"]], ["block_15", [" Element \n Reactants \n Products \n Balanced? \n"]], ["block_16", ["N\n1\n2 = 2\n1\n2 = 2\n2 = 2, yes\n"]], ["block_17", ["O\n1\n2 = 2\n1\n5 = 5\n2 \u2260 5, no\n"]], ["block_18", [" 4.1 \u2022 Writing and Balancing Chemical Equations \n 163 \n"]]], "page_177": [["block_0", [" 164 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", ["Finally with regard to balanced equations, recall that convention dictates use of the smallest whole-number\ncoefficients. Although the equation for the reaction between molecular nitrogen and molecular hydrogen to\nproduce ammonia is, indeed, balanced,\n"]], ["block_2", ["provisional balanced equation:\n"]], ["block_3", ["A conventional balanced equation with integer-only coefficients is derived by multiplying each coefficient by 2:\n"]], ["block_4", ["the coefficients are not the smallest possible integers representing the relative numbers of reactant and\nproduct molecules. Dividing each coefficient by the greatest common factor, 3, gives the preferred equation:\n"]], ["block_5", ["Use this interactive tutorial (http://openstax.org/l/16BalanceEq) for additional practice balancing equations.\n"]], ["block_6", [" Additional Information in Chemical Equations \n"]], ["block_7", ["The physical states of reactants and products in chemical equations very often are indicated with a\nparenthetical abbreviation following the formulas. Common abbreviations include s for solids, l for liquids, g\nfor gases, and aq for substances dissolved in water (aqueous solutions, as introduced in the preceding\nchapter). These notations are illustrated in the example equation here:\n"]], ["block_8", ["This equation represents the reaction that takes place when sodium metal is placed in water. The solid sodium\nreacts with liquid water to produce molecular hydrogen gas and the ionic compound sodium hydroxide (a solid\nin pure form, but readily dissolved in water).\n"]], ["block_9", ["Special conditions necessary for a reaction are sometimes designated by writing a word or symbol above or\nbelow the equation\u2019s arrow. For example, a reaction carried out by heating may be indicated by the uppercase\nGreek letter delta (\u0394) over the arrow.\n"]], ["block_10", ["Other examples of these special conditions will be encountered in more depth in later chapters.\n"]], ["block_11", [" Equations for Ionic Reactions \n"]], ["block_12", ["Given the abundance of water on earth, it stands to reason that a great many chemical reactions take place in\naqueous media. When ions are involved in these reactions, the chemical equations may be written with various\nlevels of detail appropriate to their intended use. To illustrate this, consider a reaction between ionic\ncompounds taking place in an aqueous solution. When aqueous solutions of CaCl2 and AgNO3 are mixed, a\nreaction takes place producing aqueous Ca(NO3)2 and solid AgCl:\n"]], ["block_13", ["This balanced equation, derived in the usual fashion, is called a molecular equation because it doesn\u2019t\nexplicitly represent the ionic species that are present in solution. When ionic compounds dissolve in water,\nthey may dissociate into their constituent ions, which are subsequently dispersed homogenously throughout\nthe resulting solution (a thorough discussion of this important process is provided in the chapter on solutions).\nIonic compounds dissolved in water are, therefore, more realistically represented as dissociated ions, in this\ncase:\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["LINK TO LEARNING\n"]]], "page_178": [["block_0", ["Unlike these three ionic compounds, AgCl does not dissolve in water to a significant extent, as signified by its\nphysical state notation, s.\n"]], ["block_1", ["Explicitly representing all dissolved ions results in a complete ionic equation . In this particular case, the\nformulas for the dissolved ionic compounds are replaced by formulas for their dissociated ions:\n"]], ["block_2", ["Examining this equation shows that two chemical species are present in identical form on both sides of the\narrow, Ca(aq) and\nThese spectator ions \u2014ions whose presence is required to maintain charge\n"]], ["block_3", ["neutrality\u2014are neither chemically nor physically changed by the process, and so they may be eliminated from\nthe equation to yield a more succinct representation called a net ionic equation :\n"]], ["block_4", ["Following the convention of using the smallest possible integers as coefficients, this equation is then written:\n"]], ["block_5", ["This net ionic equation indicates that solid silver chloride may be produced from dissolved chloride and\nsilver(I) ions, regardless of the source of these ions. These molecular and complete ionic equations provide\nadditional information, namely, the ionic compounds used as sources of Cland Ag.\n"]], ["block_6", [" Ionic and Molecular Equations \n"]], ["block_7", ["When carbon dioxide is dissolved in an aqueous solution of sodium hydroxide, the mixture reacts to yield\naqueous sodium carbonate and liquid water. Write balanced molecular, complete ionic, and net ionic equations\nfor this process.\n"]], ["block_8", [" Solution \n"]], ["block_9", ["Begin by identifying formulas for the reactants and products and arranging them properly in chemical\nequation form:\n"]], ["block_10", ["Balance is achieved easily in this case by changing the coefficient for NaOH to 2, resulting in the molecular\nequation for this reaction:\n"]], ["block_11", ["The two dissolved ionic compounds, NaOH and Na2CO3, can be represented as dissociated ions to yield the\ncomplete ionic equation:\n"]], ["block_12", ["Finally, identify the spectator ion(s), in this case Na(aq), and remove it from each side of the equation to\ngenerate the net ionic equation:\n"]], ["block_13", ["EXAMPLE 4.2\n"]], ["block_14", [" 4.1 \u2022 Writing and Balancing Chemical Equations \n 165 \n"]]], "page_179": [["block_0", [" 166 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["Diatomic chlorine and sodium hydroxide (lye) are commodity chemicals produced in large quantities, along\nwith diatomic hydrogen, via the electrolysis of brine, according to the following unbalanced equation:\n"]], ["block_3", ["Write balanced molecular, complete ionic, and net ionic equations for this process.\n"]], ["block_4", [" Answer: \n"]], ["block_5", [" 4.2 Classifying Chemical Reactions \n"]], ["block_6", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_7", ["Humans interact with one another in various and complex ways, and we classify these interactions according\nto common patterns of behavior. When two humans exchange information, we say they are communicating.\nWhen they exchange blows with their fists or feet, we say they are fighting. Faced with a wide range of varied\ninteractions between chemical substances, scientists have likewise found it convenient (or even necessary) to\nclassify chemical interactions by identifying common patterns of reactivity. This module will provide an\nintroduction to three of the most prevalent types of chemical reactions: precipitation, acid-base, and\noxidation-reduction.\n"]], ["block_8", [" Precipitation Reactions and Solubility Rules \n"]], ["block_9", ["A precipitation reaction is one in which dissolved substances react to form one (or more) solid products.\nMany reactions of this type involve the exchange of ions between ionic compounds in aqueous solution and are\nsometimes referred to as double displacement, double replacement, or metathesis reactions. These reactions\nare common in nature and are responsible for the formation of coral reefs in ocean waters and kidney stones\nin animals. They are used widely in industry for production of a number of commodity and specialty\nchemicals. Precipitation reactions also play a central role in many chemical analysis techniques, including\nspot tests used to identify metal ions and gravimetric methods for determining the composition of matter (see\nthe last module of this chapter).\n"]], ["block_10", ["The extent to which a substance may be dissolved in water, or any solvent, is quantitatively expressed as its\n solubility , defined as the maximum concentration of a substance that can be achieved under specified\nconditions. Substances with relatively large solubilities are said to be soluble . A substance will precipitate \nwhen solution conditions are such that its concentration exceeds its solubility. Substances with relatively low\nsolubilities are said to be insoluble , and these are the substances that readily precipitate from solution. More\ninformation on these important concepts is provided in a later chapter on solutions. For purposes of predicting\nthe identities of solids formed by precipitation reactions, one may simply refer to patterns of solubility that\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["\u2022\nDefine three common types of chemical reactions (precipitation, acid-base, and oxidation-reduction)\n"]], ["block_13", ["\u2022\nClassify chemical reactions as one of these three types given appropriate descriptions or chemical equations\n"]], ["block_14", ["\u2022\nIdentify common acids and bases\n"]], ["block_15", ["\u2022\nPredict the solubility of common inorganic compounds by using solubility rules\n"]], ["block_16", ["\u2022\nCompute the oxidation states for elements in compounds\n"]]], "page_180": [["block_0", ["have been observed for many ionic compounds (Table 4.1).\n"]], ["block_1", ["A vivid example of precipitation is observed when solutions of potassium iodide and lead nitrate are mixed,\nresulting in the formation of solid lead iodide:\n"]], ["block_2", ["This observation is consistent with the solubility guidelines: The only insoluble compound among all those\ninvolved is lead iodide, one of the exceptions to the general solubility of iodide salts.\n"]], ["block_3", ["The net ionic equation representing this reaction is:\n"]], ["block_4", [" TABLE 4.1 \n"]], ["block_5", [" Soluble Ionic Compounds \n"]], ["block_6", [" Insoluble Ionic Compounds \n"]], ["block_7", ["contain these ions\nexceptions\n"]], ["block_8", ["NH4\n"]], ["block_9", ["group I cations:\n"]], ["block_10", ["Li\n"]], ["block_11", ["Na\n"]], ["block_12", ["K\n"]], ["block_13", ["Rb\n"]], ["block_14", ["Cs\n"]], ["block_15", ["Cl\n"]], ["block_16", ["Br\n"]], ["block_17", ["I\n"]], ["block_18", ["F\ncompounds with group 2 metal cations, Pb, and Fe\n"]], ["block_19", ["C2H3O2\n"]], ["block_20", ["HCO3\n"]], ["block_21", ["NO3\n"]], ["block_22", ["ClO3\n"]], ["block_23", ["SO4\ncompounds with Ag, Ba, Ca, Hg2, Pband Sr\n"]], ["block_24", ["contain these ions\nexceptions\n"]], ["block_25", ["CO3\n"]], ["block_26", ["CrO4\n"]], ["block_27", ["PO4\n"]], ["block_28", ["S\n"]], ["block_29", ["OH\ncompounds with group 1 cations and Ba\n"]], ["block_30", ["none\n"]], ["block_31", ["compounds with Ag, Hg2, and Pb\n"]], ["block_32", ["none\n"]], ["block_33", ["compounds with group 1 cations and NH4\n"]], ["block_34", [" 4.2 \u2022 Classifying Chemical Reactions \n 167 \n"]]], "page_181": [["block_0", [" 168 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", ["Lead iodide is a bright yellow solid that was formerly used as an artist\u2019s pigment known as iodine yellow\n(Figure 4.4). The properties of pure PbI2 crystals make them useful for fabrication of X-ray and gamma ray\ndetectors.\n"]], ["block_2", [" FIGURE 4.4 \nA precipitate of PbI2 forms when solutions containing Pband Iare mixed. (credit: Der Kreole/\n"]], ["block_3", ["Wikimedia Commons)\n"]], ["block_4", ["The solubility guidelines in Table 4.1 may be used to predict whether a precipitation reaction will occur when\nsolutions of soluble ionic compounds are mixed together. One merely needs to identify all the ions present in\nthe solution and then consider if possible cation/anion pairing could result in an insoluble compound. For\nexample, mixing solutions of silver nitrate and sodium chloride will yield a solution containing Ag,\nNa, and Clions. Aside from the two ionic compounds originally present in the solutions, AgNO3 and NaCl,\ntwo additional ionic compounds may be derived from this collection of ions: NaNO3 and AgCl. The solubility\nguidelines indicate all nitrate salts are soluble but that AgCl is one of insoluble. A precipitation reaction,\ntherefore, is predicted to occur, as described by the following equations:\n"]], ["block_5", [" Predicting Precipitation Reactions \n"]], ["block_6", ["Predict the result of mixing reasonably concentrated solutions of the following ionic compounds. If\nprecipitation is expected, write a balanced net ionic equation for the reaction.\n"]], ["block_7", ["(a) potassium sulfate and barium nitrate\n"]], ["block_8", ["(b) lithium chloride and silver acetate\n"]], ["block_9", ["(c) lead nitrate and ammonium carbonate\n"]], ["block_10", [" Solution \n"]], ["block_11", ["(a) The two possible products for this combination are KNO3 and BaSO4. The solubility guidelines indicate\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["EXAMPLE 4.3\n"]], ["block_14", [{"image_0": "181_0.png", "coords": [189, 121, 423, 377]}]]], "page_182": [["block_0", ["BaSO4 is insoluble, and so a precipitation reaction is expected. The net ionic equation for this reaction, derived\nin the manner detailed in the previous module, is\n"]], ["block_1", ["(b) The two possible products for this combination are LiC2H3O2 and AgCl. The solubility guidelines indicate\nAgCl is insoluble, and so a precipitation reaction is expected. The net ionic equation for this reaction, derived\nin the manner detailed in the previous module, is\n"]], ["block_2", ["(c) The two possible products for this combination are PbCO3 and NH4NO3. The solubility guidelines indicate\nPbCO3 is insoluble, and so a precipitation reaction is expected. The net ionic equation for this reaction, derived\nin the manner detailed in the previous module, is\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["Which solution could be used to precipitate the barium ion, Ba, in a water sample: sodium chloride, sodium\nhydroxide, or sodium sulfate? What is the formula for the expected precipitate?\n"]], ["block_5", [" Answer: \nsodium sulfate, BaSO4\n"]], ["block_6", [" Acid-Base Reactions \n"]], ["block_7", ["An acid-base reaction is one in which a hydrogen ion, H, is transferred from one chemical species to another.\nSuch reactions are of central importance to numerous natural and technological processes, ranging from the\nchemical transformations that take place within cells and the lakes and oceans, to the industrial-scale\nproduction of fertilizers, pharmaceuticals, and other substances essential to society. The subject of acid-base\nchemistry, therefore, is worthy of thorough discussion, and a full chapter is devoted to this topic later in the\ntext.\n"]], ["block_8", ["For purposes of this brief introduction, we will consider only the more common types of acid-base reactions\nthat take place in aqueous solutions. In this context, an acid is a substance that will dissolve in water to yield\nhydronium ions, H3O. As an example, consider the equation shown here:\n"]], ["block_9", ["The process represented by this equation confirms that hydrogen chloride is an acid. When dissolved in water,\nH3Oions are produced by a chemical reaction in which Hions are transferred from HCl molecules to H2O\nmolecules (Figure 4.5).\n"]], ["block_10", [" 4.2 \u2022 Classifying Chemical Reactions \n 169 \n"]]], "page_183": [["block_0", [" 170 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", [" FIGURE 4.5 \nWhen hydrogen chloride gas dissolves in water, (a) it reacts as an acid, transferring protons to water\n"]], ["block_2", ["molecules to yield (b) hydronium ions (and solvated chloride ions).\n"]], ["block_3", ["The nature of HCl is such that its reaction with water as just described is essentially 100% efficient: Virtually\nevery HCl molecule that dissolves in water will undergo this reaction. Acids that completely react in this\nfashion are called strong acids , and HCl is one among just a handful of common acid compounds that are\nclassified as strong (Table 4.2). A far greater number of compounds behave as weak acids and only partially\nreact with water, leaving a large majority of dissolved molecules in their original form and generating a\nrelatively small amount of hydronium ions. Weak acids are commonly encountered in nature, being the\nsubstances partly responsible for the tangy taste of citrus fruits, the stinging sensation of insect bites, and the\nunpleasant smells associated with body odor. A familiar example of a weak acid is acetic acid, the main\ningredient in food vinegars:\n"]], ["block_4", ["When dissolved in water under typical conditions, only about 1% of acetic acid molecules are present in the\nionized form,\n(Figure 4.6). (The use of a double-arrow in the equation above denotes the partial\n"]], ["block_5", ["reaction aspect of this process, a concept addressed fully in the chapters on chemical equilibrium.)\n"]], ["block_6", [" FIGURE 4.6 \n(a) Fruits such as oranges, lemons, and grapefruit contain the weak acid citric acid. (b) Vinegars\n"]], ["block_7", ["contain the weak acid acetic acid. (credit a: modification of work by Scott Bauer; credit b: modification of work by\nBr\u00fccke-Osteuropa/Wikimedia Commons)\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", [{"image_0": "183_0.png", "coords": [130, 57, 481, 257]}]], ["block_10", [{"image_1": "183_1.png", "coords": [189, 473, 423, 682]}]]], "page_184": [["block_0", ["A base is a substance that will dissolve in water to yield hydroxide ions, OH. The most common bases are\nionic compounds composed of alkali or alkaline earth metal cations (groups 1 and 2) combined with the\nhydroxide ion\u2014for example, NaOH and Ca(OH)2. Unlike the acid compounds discussed previously, these\ncompounds do not react chemically with water; instead they dissolve and dissociate, releasing hydroxide ions\ndirectly into the solution. For example, KOH and Ba(OH)2 dissolve in water and dissociate completely to\nproduce cations (Kand Ba, respectively) and hydroxide ions, OH. These bases, along with other hydroxides\nthat completely dissociate in water, are considered strong bases .\n"]], ["block_1", ["Consider as an example the dissolution of lye (sodium hydroxide) in water:\n"]], ["block_2", ["This equation confirms that sodium hydroxide is a base. When dissolved in water, NaOH dissociates to yield\nNaand OHions. This is also true for any other ionic compound containing hydroxide ions. Since the\ndissociation process is essentially complete when ionic compounds dissolve in water under typical conditions,\nNaOH and other ionic hydroxides are all classified as strong bases.\n"]], ["block_3", ["Unlike ionic hydroxides, some compounds produce hydroxide ions when dissolved by chemically reacting with\nwater molecules. In all cases, these compounds react only partially and so are classified as weak bases . These\ntypes of compounds are also abundant in nature and important commodities in various technologies. For\nexample, global production of the weak base ammonia is typically well over 100 metric tons annually, being\nwidely used as an agricultural fertilizer, a raw material for chemical synthesis of other compounds, and an\nactive ingredient in household cleaners (Figure 4.7). When dissolved in water, ammonia reacts partially to\nyield hydroxide ions, as shown here:\n"]], ["block_4", ["This is, by definition, an acid-base reaction, in this case involving the transfer of Hions from water molecules\nto ammonia molecules. Under typical conditions, only about 1% of the dissolved ammonia is present as\nions.\n"]], ["block_5", [" TABLE 4.2 \n"]], ["block_6", [" Compound Formula \n Name in Aqueous Solution \n"]], ["block_7", ["HBr\nhydrobromic acid\n"]], ["block_8", ["HCl\nhydrochloric acid\n"]], ["block_9", ["HI\nhydroiodic acid\n"]], ["block_10", ["HNO3\nnitric acid\n"]], ["block_11", ["HClO4\nperchloric acid\n"]], ["block_12", ["H2SO4\nsulfuric acid\n"]], ["block_13", ["Common Strong Acids\n"]], ["block_14", [" 4.2 \u2022 Classifying Chemical Reactions \n 171 \n"]]], "page_185": [["block_0", [" 172 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", [" FIGURE 4.7 \nAmmonia is a weak base used in a variety of applications. (a) Pure ammonia is commonly applied as\n"]], ["block_2", ["an agricultural fertilizer. (b) Dilute solutions of ammonia are effective household cleansers. (credit a: modification of\nwork by National Resources Conservation Service; credit b: modification of work by pat00139)\n"]], ["block_3", ["A neutralization reaction is a specific type of acid-base reaction in which the reactants are an acid and a base\n(but not water), and the products are often a salt and water\n"]], ["block_4", ["To illustrate a neutralization reaction, consider what happens when a typical antacid such as milk of magnesia\n(an aqueous suspension of solid Mg(OH)2) is ingested to ease symptoms associated with excess stomach acid\n(HCl):\n"]], ["block_5", ["Note that in addition to water, this reaction produces a salt, magnesium chloride.\n"]], ["block_6", [" Writing Equations for Acid-Base Reactions \n"]], ["block_7", ["Write balanced chemical equations for the acid-base reactions described here:\n"]], ["block_8", ["(a) the weak acid hydrogen hypochlorite reacts with water\n"]], ["block_9", ["(b) a solution of barium hydroxide is neutralized with a solution of nitric acid\n"]], ["block_10", [" Solution \n"]], ["block_11", ["(a) The two reactants are provided, HOCl and H2O. Since the substance is reported to be an acid, its reaction\nwith water will involve the transfer of Hfrom HOCl to H2O to generate hydronium ions, H3Oand hypochlorite\nions, OCl.\n"]], ["block_12", ["A double-arrow is appropriate in this equation because it indicates the HOCl is a weak acid that has not reacted\ncompletely.\n"]], ["block_13", ["(b) The two reactants are provided, Ba(OH)2 and HNO3. Since this is a neutralization reaction, the two products\nwill be water and a salt composed of the cation of the ionic hydroxide (Ba) and the anion generated when the\nacid transfers its hydrogen ion\n"]], ["block_14", [" Check Your Learning \n"]], ["block_15", ["Write the net ionic equation representing the neutralization of any strong acid with an ionic hydroxide. (Hint:\nConsider the ions produced when a strong acid is dissolved in water.)\n"]], ["block_16", [" Answer: \n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["EXAMPLE 4.4\n"]], ["block_19", [{"image_0": "185_0.png", "coords": [130, 57, 481, 171]}]]], "page_186": [["block_0", ["Chemistry in Everyday Life\n"]], ["block_1", [" Stomach Antacids \nOur stomachs contain a solution of roughly 0.03 M HCl, which helps us digest the food we eat. The burning\nsensation associated with heartburn is a result of the acid of the stomach leaking through the muscular\nvalve at the top of the stomach into the lower reaches of the esophagus. The lining of the esophagus is not\nprotected from the corrosive effects of stomach acid the way the lining of the stomach is, and the results\ncan be very painful. When we have heartburn, it feels better if we reduce the excess acid in the esophagus\nby taking an antacid. As you may have guessed, antacids are bases. One of the most common antacids is\ncalcium carbonate, CaCO3. The reaction,\n"]], ["block_2", ["not only neutralizes stomach acid, it also produces CO2(g), which may result in a satisfying belch.\n"]], ["block_3", ["Milk of Magnesia is a suspension of the sparingly soluble base magnesium hydroxide, Mg(OH)2. It works\naccording to the reaction:\n"]], ["block_4", ["The hydroxide ions generated in this equilibrium then go on to react with the hydronium ions from the\nstomach acid, so that:\n"]], ["block_5", ["This reaction does not produce carbon dioxide, but magnesium-containing antacids can have a laxative\neffect. Several antacids have aluminum hydroxide, Al(OH)3, as an active ingredient. The aluminum\nhydroxide tends to cause constipation, and some antacids use aluminum hydroxide in concert with\nmagnesium hydroxide to balance the side effects of the two substances.\n"]], ["block_6", ["Chemistry in Everyday Life\n"]], ["block_7", [" Culinary Aspects of Chemistry \nExamples of acid-base chemistry are abundant in the culinary world. One example is the use of baking\nsoda, or sodium bicarbonate in baking. NaHCO3 is a base. When it reacts with an acid such as lemon juice,\nbuttermilk, or sour cream in a batter, bubbles of carbon dioxide gas are formed from decomposition of the\nresulting carbonic acid, and the batter \u201crises.\u201d Baking powder is a combination of sodium bicarbonate, and\none or more acid salts that react when the two chemicals come in contact with water in the batter.\n"]], ["block_8", ["Many people like to put lemon juice or vinegar, both of which are acids, on cooked fish (Figure 4.8). It turns\nout that fish have volatile amines (bases) in their systems, which are neutralized by the acids to yield\ninvolatile ammonium salts. This reduces the odor of the fish, and also adds a \u201csour\u201d taste that we seem to\nenjoy.\n"]], ["block_9", [" 4.2 \u2022 Classifying Chemical Reactions \n 173 \n"]]], "page_187": [["block_0", [" 174 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", ["Explore the microscopic view (http://openstax.org/l/16AcidsBases) of strong and weak acids and bases.\n"]], ["block_2", [" Oxidation-Reduction Reactions \n"]], ["block_3", ["Earth\u2019s atmosphere contains about 20% molecular oxygen, O2, a chemically reactive gas that plays an essential\nrole in the metabolism of aerobic organisms and in many environmental processes that shape the world. The\nterm oxidation was originally used to describe chemical reactions involving O2, but its meaning has evolved to\nrefer to a broad and important reaction class known as oxidation-reduction (redox) reactions. A few examples\nof such reactions will be used to develop a clear picture of this classification.\n"]], ["block_4", ["Some redox reactions involve the transfer of electrons between reactant species to yield ionic products, such\nas the reaction between sodium and chlorine to yield sodium chloride:\n"]], ["block_5", ["It is helpful to view the process with regard to each individual reactant, that is, to represent the fate of each\nreactant in the form of an equation called a half-reaction :\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [" FIGURE 4.8 \nA neutralization reaction takes place between citric acid in lemons or acetic acid in vinegar, and\n"]], ["block_8", ["the bases in the flesh of fish.\n"]], ["block_9", ["Pickling is a method used to preserve vegetables using a naturally produced acidic environment. The\nvegetable, such as a cucumber, is placed in a sealed jar submerged in a brine solution. The brine solution\nfavors the growth of beneficial bacteria and suppresses the growth of harmful bacteria. The beneficial\nbacteria feed on starches in the cucumber and produce lactic acid as a waste product in a process called\nfermentation. The lactic acid eventually increases the acidity of the brine to a level that kills any harmful\nbacteria, which require a basic environment. Without the harmful bacteria consuming the cucumbers they\nare able to last much longer than if they were unprotected. A byproduct of the pickling process changes the\nflavor of the vegetables with the acid making them taste sour.\n"]], ["block_10", [{"image_0": "187_0.png", "coords": [90, 57, 522, 338]}]], ["block_11", ["LINK TO LEARNING\n"]]], "page_188": [["block_0", ["These equations show that Na atoms lose electrons while Cl atoms (in the Cl2 molecule) gain electrons, the \u201cs\u201d\nsubscripts for the resulting ions signifying they are present in the form of a solid ionic compound. For redox\nreactions of this sort, the loss and gain of electrons define the complementary processes that occur:\n"]], ["block_1", ["In this reaction, then, sodium is oxidized and chlorine undergoes reduction . Viewed from a more active\nperspective, sodium functions as a reducing agent (reductant) , since it provides electrons to (or reduces)\nchlorine. Likewise, chlorine functions as an oxidizing agent (oxidant) , as it effectively removes electrons from\n(oxidizes) sodium.\n"]], ["block_2", ["Some redox processes, however, do not involve the transfer of electrons. Consider, for example, a reaction\nsimilar to the one yielding NaCl:\n"]], ["block_3", ["The product of this reaction is a covalent compound, so transfer of electrons in the explicit sense is not\ninvolved. To clarify the similarity of this reaction to the previous one and permit an unambiguous definition of\nredox reactions, a property called oxidation number has been defined. The oxidation number (or oxidation \n state ) of an element in a compound is the charge its atoms would possess if the compound were ionic. The\nfollowing guidelines are used to assign oxidation numbers to each element in a molecule or ion.\n"]], ["block_4", ["Note: The proper convention for reporting charge is to write the number first, followed by the sign (e.g., 2+),\nwhile oxidation number is written with the reversed sequence, sign followed by number (e.g., +2). This\nconvention aims to emphasize the distinction between these two related properties.\n"]], ["block_5", [" Assigning Oxidation Numbers \n"]], ["block_6", ["Follow the guidelines in this section of the text to assign oxidation numbers to all the elements in the following\nspecies:\n"]], ["block_7", ["(a) H2S\n"]], ["block_8", ["(b)\n"]], ["block_9", ["(c) Na2SO4\n"]], ["block_10", ["1.\nThe oxidation number of an atom in an elemental substance is zero.\n"]], ["block_11", ["2.\nThe oxidation number of a monatomic ion is equal to the ion\u2019s charge.\n"]], ["block_12", ["3.\nOxidation numbers for common nonmetals are usually assigned as follows:\n"]], ["block_13", ["4.\nThe sum of oxidation numbers for all atoms in a molecule or polyatomic ion equals the charge on the\nmolecule or ion.\n"]], ["block_14", ["\u25e6\nHydrogen: +1 when combined with nonmetals, \u22121 when combined with metals\n"]], ["block_15", ["\u25e6\nOxygen: \u22122 in most compounds, sometimes \u22121 (so-called peroxides,\nvery rarely\n(so-called\n"]], ["block_16", ["\u25e6\nHalogens: \u22121 for F always, \u22121 for other halogens except when combined with oxygen or other halogens\n(positive oxidation numbers in these cases, varying values)\n"]], ["block_17", ["superoxides,\npositive values when combined with F (values vary)\n"]], ["block_18", ["EXAMPLE 4.5\n"]], ["block_19", [" 4.2 \u2022 Classifying Chemical Reactions \n 175 \n"]]], "page_189": [["block_0", [" 176 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", [" Solution \n"]], ["block_2", ["(a) According to guideline 3, the oxidation number for H is +1.\n"]], ["block_3", ["Using this oxidation number and the compound\u2019s formula, guideline 4 may then be used to calculate the\noxidation number for sulfur:\n"]], ["block_4", ["(b) Guideline 3 suggests the oxidation number for oxygen is \u22122.\n"]], ["block_5", ["Using this oxidation number and the ion\u2019s formula, guideline 4 may then be used to calculate the oxidation\nnumber for sulfur:\n"]], ["block_6", ["(c) For ionic compounds, it\u2019s convenient to assign oxidation numbers for the cation and anion separately.\n"]], ["block_7", ["According to guideline 2, the oxidation number for sodium is +1.\n"]], ["block_8", ["Assuming the usual oxidation number for oxygen (\u22122 per guideline 3), the oxidation number for sulfur is\ncalculated as directed by guideline 4:\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["Assign oxidation states to the elements whose atoms are underlined in each of the following compounds or\nions:\n"]], ["block_11", ["(a) KNO3\n"]], ["block_12", ["(b) AlH3\n"]], ["block_13", ["(c)\n"]], ["block_14", ["(d)\n"]], ["block_15", [" Answer: \n(a) N, +5; (b) Al, +3; (c) N, \u22123; (d) P, +5\n"]], ["block_16", ["Using the oxidation number concept, an all-inclusive definition of redox reaction has been established.\n Oxidation-reduction (redox) reactions are those in which one or more elements involved undergo a change\nin oxidation number. (While the vast majority of redox reactions involve changes in oxidation number for two\nor more elements, a few interesting exceptions to this rule do exist Example 4.6.) Definitions for the\ncomplementary processes of this reaction class are correspondingly revised as shown here:\n"]], ["block_17", ["Returning to the reactions used to introduce this topic, they may now both be identified as redox processes. In\nthe reaction between sodium and chlorine to yield sodium chloride, sodium is oxidized (its oxidation number\nincreases from 0 in Na to +1 in NaCl) and chlorine is reduced (its oxidation number decreases from 0 in Cl2 to\n\u22121 in NaCl). In the reaction between molecular hydrogen and chlorine, hydrogen is oxidized (its oxidation\nnumber increases from 0 in H2 to +1 in HCl) and chlorine is reduced (its oxidation number decreases from 0 in\n"]], ["block_18", [" Access for free at openstax.org \n"]]], "page_190": [["block_0", ["Cl2 to \u22121 in HCl).\n"]], ["block_1", ["Several subclasses of redox reactions are recognized, including combustion reactions in which the reductant\n(also called a fuel) and oxidant (often, but not necessarily, molecular oxygen) react vigorously and produce\nsignificant amounts of heat, and often light, in the form of a flame. Solid rocket-fuel reactions such as the one\ndepicted in Figure 4.1 are combustion processes. A typical propellant reaction in which solid aluminum is\noxidized by ammonium perchlorate is represented by this equation:\n"]], ["block_2", ["Watch a brief video (http://openstax.org/l/16hybridrocket) showing the test firing of a small-scale, prototype,\nhybrid rocket engine planned for use in the new Space Launch System being developed by NASA. The first\nengines firing at\n3 s (green flame) use a liquid fuel/oxidant mixture, and the second, more powerful engines firing at 4 s (yellow\nflame) use a solid mixture.\n"]], ["block_3", [" Single-displacement (replacement) reactions are redox reactions in which an ion in solution is displaced (or\nreplaced) via the oxidation of a metallic element. One common example of this type of reaction is the acid\noxidation of certain metals:\n"]], ["block_4", ["Metallic elements may also be oxidized by solutions of other metal salts; for example:\n"]], ["block_5", ["This reaction may be observed by placing copper wire in a solution containing a dissolved silver salt. Silver\nions in solution are reduced to elemental silver at the surface of the copper wire, and the resulting Cuions\ndissolve in the solution to yield a characteristic blue color (Figure 4.9).\n"]], ["block_6", [" FIGURE 4.9 \n(a) A copper wire is shown next to a solution containing silver(I) ions. (b) Displacement of dissolved\n"]], ["block_7", ["silver ions by copper ions results in (c) accumulation of gray-colored silver metal on the wire and development of a\nblue color in the solution, due to dissolved copper ions. (credit: modification of work by Mark Ott)\n"]], ["block_8", [" Describing Redox Reactions \n"]], ["block_9", ["Identify which equations represent redox reactions, providing a name for the reaction if appropriate. For those\nreactions identified as redox, name the oxidant and reductant.\n"]], ["block_10", ["(a)\n"]], ["block_11", ["(b)\n"]], ["block_12", ["(c)\n"]], ["block_13", ["(d)\n"]], ["block_14", ["(e)\n"]], ["block_15", ["LINK TO LEARNING\n"]], ["block_16", ["EXAMPLE 4.6\n"]], ["block_17", [{"image_0": "190_0.png", "coords": [130, 407, 481, 490]}]], ["block_18", [" 4.2 \u2022 Classifying Chemical Reactions \n 177 \n"]]], "page_191": [["block_0", [" 178 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", [" Solution \n"]], ["block_2", ["Redox reactions are identified per definition if one or more elements undergo a change in oxidation number.\n"]], ["block_3", ["(a) This is not a redox reaction, since oxidation numbers remain unchanged for all elements.\n"]], ["block_4", ["(b) This is a redox reaction. Gallium is oxidized, its oxidation number increasing from 0 in Ga(l) to +3 in\nGaBr3(s). The reducing agent is Ga(l). Bromine is reduced, its oxidation number decreasing from 0 in Br2(l) to\n\u22121 in GaBr3(s). The oxidizing agent is Br2(l).\n"]], ["block_5", ["(c) This is a redox reaction. It is a particularly interesting process, as it involves the same element, oxygen,\nundergoing both oxidation and reduction (a so-called disproportionation reaction). Oxygen is oxidized, its\noxidation number increasing from \u22121 in H2O2(aq) to 0 in O2(g). Oxygen is also reduced, its oxidation number\ndecreasing from \u22121 in H2O2(aq) to \u22122 in H2O(l). For disproportionation reactions, the same substance\nfunctions as an oxidant and a reductant.\n"]], ["block_6", ["(d) This is not a redox reaction, since oxidation numbers remain unchanged for all elements.\n"]], ["block_7", ["(e) This is a redox reaction (combustion). Carbon is oxidized, its oxidation number increasing from \u22122 in\nC2H4(g) to +4 in CO2(g). The reducing agent (fuel) is C2H4(g). Oxygen is reduced, its oxidation number\ndecreasing from 0 in O2(g) to \u22122 in H2O(l). The oxidizing agent is O2(g).\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["This equation describes the production of tin(II) chloride:\n"]], ["block_10", ["Is this a redox reaction? If so, provide a more specific name for the reaction if appropriate, and identify the\noxidant and reductant.\n"]], ["block_11", [" Answer: \nYes, a single-replacement reaction. Sn(s)is the reductant, HCl(g) is the oxidant.\n"]], ["block_12", [" Balancing Redox Reactions via the Half-Reaction Method \nRedox reactions that take place in aqueous media often involve water, hydronium ions, and hydroxide ions as\nreactants or products. Although these species are not oxidized or reduced, they do participate in chemical\nchange in other ways (e.g., by providing the elements required to form oxyanions). Equations representing\nthese reactions are sometimes very difficult to balance by inspection, so systematic approaches have been\ndeveloped to assist in the process. One very useful approach is to use the method of half-reactions, which\ninvolves the following steps:\n"]], ["block_13", ["1. Write the two half-reactions representing the redox process.\n"]], ["block_14", ["2. Balance all elements except oxygen and hydrogen.\n"]], ["block_15", ["3. Balance oxygen atoms by adding H2O molecules.\n"]], ["block_16", ["4. Balance hydrogen atoms by adding Hions.\n"]], ["block_17", ["5. Balance charge by adding electrons.\n"]], ["block_18", ["6. If necessary, multiply each half-reaction\u2019s coefficients by the smallest possible integers to yield equal\nnumbers of electrons in each.\n"]], ["block_19", ["7. Add the balanced half-reactions together and simplify by removing species that appear on both sides of the\nequation.\n"]], ["block_20", ["8. For reactions occurring in basic media (excess hydroxide ions), carry out these additional steps:\n"]], ["block_21", [" Access for free at openstax.org \n"]], ["block_22", ["b.\nOn the side of the equation containing both Hand OHions, combine these ions to yield water molecules.\n"]], ["block_23", ["a.\nAdd OHions to both sides of the equation in numbers equal to the number of Hions.\n"]], ["block_24", ["c.\nSimplify the equation by removing any redundant water molecules.\n"]]], "page_192": [["block_0", ["9. Finally, check to see that both the number of atoms and the total chargesare balanced.\n"]], ["block_1", [" Balancing Redox Reactions in Acidic Solution \n"]], ["block_2", ["Write a balanced equation for the reaction between dichromate ion and iron(II) to yield iron(III) and\nchromium(III) in acidic solution.\n"]], ["block_3", [" Solution \n"]], ["block_4", ["1 The requirement of \u201ccharge balance\u201d is just a specific type of \u201cmass balance\u201d in which the species in question are electrons. An\nequation must represent equal numbers of electrons on the reactant and product sides, and so both atoms and charges must be\nbalanced.\n"]], ["block_5", ["Step 1.\nWrite the two half-reactions.\n"]], ["block_6", ["Step 2.\nBalance all elements except oxygen and hydrogen. The iron half-reaction is already balanced, but the\nchromium half-reaction shows two Cr atoms on the left and one Cr atom on the right. Changing the\ncoefficient on the right side of the equation to 2 achieves balance with regard to Cr atoms.\n"]], ["block_7", ["Step 3.\nBalance oxygen atoms by adding H2O molecules. The iron half-reaction does not contain O atoms. The\nchromium half-reaction shows seven O atoms on the left and none on the right, so seven water molecules\nare added to the right side.\n"]], ["block_8", ["Step 4.\nBalance hydrogen atoms by adding Hions. The iron half-reaction does not contain H atoms. The\nchromium half-reaction shows 14 H atoms on the right and none on the left, so 14 hydrogen ions are\nadded to the left side.\n"]], ["block_9", ["Step 5.\nBalance charge by adding electrons. The iron half-reaction shows a total charge of 2+ on the left side (1\nFeion) and 3+ on the right side (1 Feion). Adding one electron to the right side brings that side\u2019s total\ncharge to (3+) + (1\u2212) = 2+, and charge balance is achieved.\n"]], ["block_10", ["Each half-reaction will contain one reactant and one product with one element in common.\n"]], ["block_11", ["The chromium half-reaction shows a total charge of (1\n2\u2212) + (14\n1+) = 12+ on the left side\n"]], ["block_12", ["ion and 14 Hions). The total charge on the right side is (2\n3+) = 6 + (2 Crions). Adding six electrons to\n"]], ["block_13", ["EXAMPLE 4.7\n"]], ["block_14", [" 4.2 \u2022 Classifying Chemical Reactions \n 179 \n"]]], "page_193": [["block_0", [" 180 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", ["A final check of atom and charge balance confirms the equation is balanced.\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["In basic solution, molecular chlorine, Cl2, reacts with hydroxide ions, OH, to yield chloride ions, Cl. and\nchlorate ions, ClO3. HINT: This is a disproportionation reaction in which the element chlorine is both oxidized\nand reduced. Write a balanced equation for this reaction.\n"]], ["block_4", [" Answer: \n"]], ["block_5", [" 4.3 Reaction Stoichiometry \n"]], ["block_6", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_7", ["A balanced chemical equation provides a great deal of information in a very succinct format. Chemical\nformulas provide the identities of the reactants and products involved in the chemical change, allowing\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["\u2022\nExplain the concept of stoichiometry as it pertains to chemical reactions\n"]], ["block_10", ["\u2022\nUse balanced chemical equations to derive stoichiometric factors relating amounts of reactants and products\n"]], ["block_11", ["\u2022\nPerform stoichiometric calculations involving mass, moles, and solution molarity\n"]], ["block_12", ["Step 6.\nMultiply the two half-reactions so the number of electrons in one reaction equals the number of electrons\nin the other reaction. To be consistent with mass conservation, and the idea that redox reactions involve\nthe transfer (not creation or destruction) of electrons, the iron half-reaction\u2019s coefficient must be\nmultiplied by 6.\n"]], ["block_13", ["Step 7.\nAdd the balanced half-reactions and cancel species that appear on both sides of the equation.\n"]], ["block_14", ["the left side will bring that side\u2019s total charge to (12+ + 6\u2212) = 6+, and charge balance is achieved.\n"]], ["block_15", ["Only the six electrons are redundant species. Removing them from each side of the equation yields the\nsimplified, balanced equation here:\n"]], ["block_16", ["Fe\n6\n6\n"]], ["block_17", ["Cr\n2\n2\n"]], ["block_18", ["O\n7\n7\n"]], ["block_19", ["H\n14\n14\n"]], ["block_20", ["charge\n24+\n24+\n"]], ["block_21", ["Reactants\nProducts\n"]]], "page_194": [["block_0", ["classification of the reaction. Coefficients provide the relative numbers of these chemical species, allowing a\nquantitative assessment of the relationships between the amounts of substances consumed and produced by\nthe reaction. These quantitative relationships are known as the reaction\u2019s stoichiometry , a term derived from\nthe Greek words stoicheion (meaning \u201celement\u201d) and metron (meaning \u201cmeasure\u201d). In this module, the use of\nbalanced chemical equations for various stoichiometric applications is explored.\n"]], ["block_1", ["The general approach to using stoichiometric relationships is similar in concept to the way people go about\nmany common activities. Food preparation, for example, offers an appropriate comparison. A recipe for\nmaking eight pancakes calls for 1 cup pancake mix,\ncup milk, and one egg. The \u201cequation\u201d representing the\n"]], ["block_2", ["preparation of pancakes per this recipe is\n"]], ["block_3", ["If two dozen pancakes are needed for a big family breakfast, the ingredient amounts must be increased\nproportionally according to the amounts given in the recipe. For example, the number of eggs required to\nmake 24 pancakes is\n"]], ["block_4", ["Balanced chemical equations are used in much the same fashion to determine the amount of one reactant\nrequired to react with a given amount of another reactant, or to yield a given amount of product, and so forth.\nThe coefficients in the balanced equation are used to derive stoichiometric factors that permit computation of\nthe desired quantity. To illustrate this idea, consider the production of ammonia by reaction of hydrogen and\nnitrogen:\n"]], ["block_5", ["This equation shows ammonia molecules are produced from hydrogen molecules in a 2:3 ratio, and\nstoichiometric factors may be derived using any amount (number) unit:\n"]], ["block_6", ["These stoichiometric factors can be used to compute the number of ammonia molecules produced from a\ngiven number of hydrogen molecules, or the number of hydrogen molecules required to produce a given\nnumber of ammonia molecules. Similar factors may be derived for any pair of substances in any chemical\nequation.\n"]], ["block_7", [" Moles of Reactant Required in a Reaction \n"]], ["block_8", ["How many moles of I2 are required to react with 0.429 mol of Al according to the following equation (see Figure\n4.10)?\n"]], ["block_9", [" FIGURE 4.10 \nAluminum and iodine react to produce aluminum iodide. The heat of the reaction vaporizes some of\n"]], ["block_10", ["the solid iodine as a purple vapor. (credit: modification of work by Mark Ott)\n"]], ["block_11", [" Solution \n"]], ["block_12", ["Referring to the balanced chemical equation, the stoichiometric factor relating the two substances of interest\n"]], ["block_13", ["EXAMPLE 4.8\n"]], ["block_14", [{"image_0": "194_0.png", "coords": [130, 592, 481, 657]}]], ["block_15", [" 4.3 \u2022 Reaction Stoichiometry \n 181 \n"]]], "page_195": [["block_0", [" 182 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", ["is\nThe molar amount of iodine is derived by multiplying the provided molar amount of aluminum by\n"]], ["block_2", ["this factor:\n"]], ["block_3", [{"image_0": "195_0.png", "coords": [72, 94, 306, 140]}]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["How many moles of Ca(OH)2 are required to react with 1.36 mol of H3PO4 to produce Ca3(PO4)2 according to\nthe equation\n"]], ["block_6", [" Answer: \n2.04 mol\n"]], ["block_7", [" Number of Product Molecules Generated by a Reaction \n"]], ["block_8", ["How many carbon dioxide molecules are produced when 0.75 mol of propane is combusted according to this\nequation?\n"]], ["block_9", [" Solution \n"]], ["block_10", ["The approach here is the same as for Example 4.8, though the absolute number of molecules is requested, not\nthe number of moles of molecules. This will simply require use of the moles-to-numbers conversion factor,\nAvogadro\u2019s number.\n"]], ["block_11", ["The balanced equation shows that carbon dioxide is produced from propane in a 3:1 ratio:\n"]], ["block_12", ["Using this stoichiometric factor, the provided molar amount of propane, and Avogadro\u2019s number,\n"]], ["block_13", [{"image_1": "195_1.png", "coords": [72, 502, 432, 551]}]], ["block_14", [" Check Your Learning \n"]], ["block_15", ["How many NH3 molecules are produced by the reaction of 4.0 mol of Ca(OH)2 according to the following\nequation:\n"]], ["block_16", [" Answer: \n4.8\n10NH3 molecules\n"]], ["block_17", ["These examples illustrate the ease with which the amounts of substances involved in a chemical reaction of\nknown stoichiometry may be related. Directly measuring numbers of atoms and molecules is, however, not an\n"]], ["block_18", [" Access for free at openstax.org \n"]], ["block_19", ["EXAMPLE 4.9\n"]]], "page_196": [["block_0", ["easy task, and the practical application of stoichiometry requires that we use the more readily measured\nproperty of mass.\n"]], ["block_1", [" Relating Masses of Reactants and Products \n"]], ["block_2", ["What mass of sodium hydroxide, NaOH, would be required to produce 16 g of the antacid milk of magnesia\n[magnesium hydroxide, Mg(OH)2] by the following reaction?\n"]], ["block_3", [" Solution \n"]], ["block_4", ["The approach used previously in Example 4.8 and Example 4.9 is likewise used here; that is, we must derive an\nappropriate stoichiometric factor from the balanced chemical equation and use it to relate the amounts of the\ntwo substances of interest. In this case, however, masses (not molar amounts) are provided and requested, so\nadditional steps of the sort learned in the previous chapter are required. The calculations required are\noutlined in this flowchart:\n"]], ["block_5", [{"image_0": "196_0.png", "coords": [72, 271, 432, 431]}]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["What mass of gallium oxide, Ga2O3, can be prepared from 29.0 g of gallium metal? The equation for the\nreaction is\n"]], ["block_8", [" Answer: \n39.0 g\n"]], ["block_9", [" Relating Masses of Reactants \n"]], ["block_10", ["What mass of oxygen gas, O2, from the air is consumed in the combustion of 702 g of octane, C8H18, one of the\nprincipal components of gasoline?\n"]], ["block_11", [" Solution \n"]], ["block_12", ["The approach required here is the same as for the Example 4.10, differing only in that the provided and\nrequested masses are both for reactant species.\n"]], ["block_13", ["EXAMPLE 4.10\n"]], ["block_14", ["EXAMPLE 4.11\n"]], ["block_15", [" 4.3 \u2022 Reaction Stoichiometry \n 183 \n"]]], "page_197": [["block_0", [" 184 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", [{"image_0": "197_0.png", "coords": [72, 57, 432, 217]}]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["What mass of CO is required to react with 25.13 g of Fe2O3 according to the equation\n"]], ["block_4", [" Answer: \n13.22 g\n"]], ["block_5", ["These examples illustrate just a few instances of reaction stoichiometry calculations. Numerous variations on\nthe beginning and ending computational steps are possible depending upon what particular quantities are\nprovided and sought (volumes, solution concentrations, and so forth). Regardless of the details, all these\ncalculations share a common essential component: the use of stoichiometric factors derived from balanced\nchemical equations. Figure 4.11 provides a general outline of the various computational steps associated with\nmany reaction stoichiometry calculations.\n"]], ["block_6", [{"image_1": "197_1.png", "coords": [72, 428, 540, 715]}]], ["block_7", [" FIGURE 4.11 \nThe flowchart depicts the various computational steps involved in most reaction stoichiometry\n"]], ["block_8", [" Access for free at openstax.org \n"]]], "page_198": [["block_0", ["calculations.\n"]], ["block_1", [" 4.4 Reaction Yields \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["The relative amounts of reactants and products represented in a balanced chemical equation are often\nreferred to as stoichiometric amounts. All the exercises of the preceding module involved stoichiometric\namounts of reactants. For example, when calculating the amount of product generated from a given amount of\nreactant, it was assumed that any other reactants required were available in stoichiometric amounts (or\ngreater). In this module, more realistic situations are considered, in which reactants are not present in\nstoichiometric amounts.\n"]], ["block_4", [" Limiting Reactant \n"]], ["block_5", ["Consider another food analogy, making grilled cheese sandwiches (Figure 4.13):\n"]], ["block_6", ["Stoichiometric amounts of sandwich ingredients for this recipe are bread and cheese slices in a 2:1 ratio.\n"]], ["block_7", ["\u2022\nExplain the concepts of theoretical yield and limiting reactants/reagents.\n"]], ["block_8", ["\u2022\nDerive the theoretical yield for a reaction under specified conditions.\n"]], ["block_9", ["\u2022\nCalculate the percent yield for a reaction.\n"]], ["block_10", ["Chemistry in Everyday Life\n"]], ["block_11", [" Airbags \n Airbags (Figure 4.12) are a safety feature provided in most automobiles since the 1990s. The effective\noperation of an airbag requires that it be rapidly inflated with an appropriate amount (volume) of gas when\nthe vehicle is involved in a collision. This requirement is satisfied in many automotive airbag systems\nthrough use of explosive chemical reactions, one common choice being the decomposition of sodium\nazide, NaN3. When sensors in the vehicle detect a collision, an electrical current is passed through a\ncarefully measured amount of NaN3 to initiate its decomposition:\n"]], ["block_12", ["This reaction is very rapid, generating gaseous nitrogen that can deploy and fully inflate a typical airbag in\na fraction of a second (~0.03\u20130.1 s). Among many engineering considerations, the amount of sodium azide\nused must be appropriate for generating enough nitrogen gas to fully inflate the air bag and ensure its\nproper function. For example, a small mass (~100 g) of NaN3 will generate approximately 50 L of N2.\n"]], ["block_13", [" FIGURE 4.12 \nAirbags deploy upon impact to minimize serious injuries to passengers. (credit: Jon Seidman)\n"]], ["block_14", [{"image_0": "198_0.png", "coords": [189, 272, 423, 448]}]], ["block_15", [" 4.4 \u2022 Reaction Yields \n 185 \n"]]], "page_199": [["block_0", [" 186 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", ["Provided with 28 slices of bread and 11 slices of cheese, one may prepare 11 sandwiches per the provided\nrecipe, using all the provided cheese and having six slices of bread left over. In this scenario, the number of\nsandwiches prepared has been limited by the number of cheese slices, and the bread slices have been\nprovided in excess.\n"]], ["block_2", [{"image_0": "199_0.png", "coords": [72, 114, 540, 373]}]], ["block_3", ["Consider this concept now with regard to a chemical process, the reaction of hydrogen with chlorine to yield\nhydrogen chloride:\n"]], ["block_4", ["The balanced equation shows the hydrogen and chlorine react in a 1:1 stoichiometric ratio. If these reactants\nare provided in any other amounts, one of the reactants will nearly always be entirely consumed, thus limiting\nthe amount of product that may be generated. This substance is the limiting reactant , and the other substance\nis the excess reactant . Identifying the limiting and excess reactants for a given situation requires computing\nthe molar amounts of each reactant provided and comparing them to the stoichiometric amounts represented\nin the balanced chemical equation. For example, imagine combining 3 moles of H2 and 2 moles of Cl2. This\nrepresents a 3:2 (or 1.5:1) ratio of hydrogen to chlorine present for reaction, which is greater than the\nstoichiometric ratio of 1:1. Hydrogen, therefore, is present in excess, and chlorine is the limiting reactant.\nReaction of all the provided chlorine (2 mol) will consume 2 mol of the 3 mol of hydrogen provided, leaving 1\nmol of hydrogen unreacted.\n"]], ["block_5", ["An alternative approach to identifying the limiting reactant involves comparing the amount of product\nexpected for the complete reaction of each reactant. Each reactant amount is used to separately calculate the\namount of product that would be formed per the reaction\u2019s stoichiometry. The reactant yielding the lesser\namount of product is the limiting reactant. For the example in the previous paragraph, complete reaction of\nthe hydrogen would yield\n"]], ["block_6", ["Complete reaction of the provided chlorine would produce\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [" FIGURE 4.13 \nSandwich making can illustrate the concepts of limiting and excess reactants.\n"]]], "page_200": [["block_0", ["The chlorine will be completely consumed once 4 moles of HCl have been produced. Since enough hydrogen\nwas provided to yield 6 moles of HCl, there will be unreacted hydrogen remaining once this reaction is\ncomplete. Chlorine, therefore, is the limiting reactant and hydrogen is the excess reactant (Figure 4.14).\n"]], ["block_1", [" FIGURE 4.14 \nWhen H2 and Cl2 are combined in nonstoichiometric amounts, one of these reactants will limit the\n"]], ["block_2", ["amount of HCl that can be produced. This illustration shows a reaction in which hydrogen is present in excess and\nchlorine is the limiting reactant.\n"]], ["block_3", ["View this interactive simulation (http://openstax.org/l/16reactantprod) illustrating the concepts of limiting and\nexcess reactants.\n"]], ["block_4", [" Identifying the Limiting Reactant \n"]], ["block_5", ["Silicon nitride is a very hard, high-temperature-resistant ceramic used as a component of turbine blades in jet\nengines. It is prepared according to the following equation:\n"]], ["block_6", ["Which is the limiting reactant when 2.00 g of Si and 1.50 g of N2 react?\n"]], ["block_7", [" Solution \n"]], ["block_8", ["Compute the provided molar amounts of reactants, and then compare these amounts to the balanced equation\nto identify the limiting reactant.\n"]], ["block_9", ["The provided Si:N2 molar ratio is:\n"]], ["block_10", ["The stoichiometric Si:N2 ratio is:\n"]], ["block_11", [{"image_0": "200_0.png", "coords": [90, 101, 522, 297]}]], ["block_12", ["LINK TO LEARNING\n"]], ["block_13", ["EXAMPLE 4.12\n"]], ["block_14", [" 4.4 \u2022 Reaction Yields \n 187 \n"]]], "page_201": [["block_0", [" 188 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", ["Comparing these ratios shows that Si is provided in a less-than-stoichiometric amount, and so is the limiting\nreactant.\n"]], ["block_2", ["Alternatively, compute the amount of product expected for complete reaction of each of the provided\nreactants. The 0.0712 moles of silicon would yield\n"]], ["block_3", ["while the 0.0535 moles of nitrogen would produce\n"]], ["block_4", ["Since silicon yields the lesser amount of product, it is the limiting reactant.\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["Which is the limiting reactant when 5.00 g of H2 and 10.0 g of O2 react and form water?\n"]], ["block_7", [" Answer: \nO2\n"]], ["block_8", [" Percent Yield \n"]], ["block_9", ["The amount of product that may be produced by a reaction under specified conditions, as calculated per the\nstoichiometry of an appropriate balanced chemical equation, is called the theoretical yield of the reaction. In\npractice, the amount of product obtained is called the actual yield , and it is often less than the theoretical yield\nfor a number of reasons. Some reactions are inherently inefficient, being accompanied by side reactions that\ngenerate other products. Others are, by nature, incomplete (consider the partial reactions of weak acids and\nbases discussed earlier in this chapter). Some products are difficult to collect without some loss, and so less\nthan perfect recovery will reduce the actual yield. The extent to which a reaction\u2019s theoretical yield is achieved\nis commonly expressed as its percent yield :\n"]], ["block_10", ["Actual and theoretical yields may be expressed as masses or molar amounts (or any other appropriate\nproperty; e.g., volume, if the product is a gas). As long as both yields are expressed using the same units, these\nunits will cancel when percent yield is calculated.\n"]], ["block_11", [" Calculation of Percent Yield \n"]], ["block_12", ["Upon reaction of 1.274 g of copper sulfate with excess zinc metal, 0.392 g copper metal was obtained\naccording to the equation:\n"]], ["block_13", ["What is the percent yield?\n"]], ["block_14", [" Solution \n"]], ["block_15", ["The provided information identifies copper sulfate as the limiting reactant, and so the theoretical yield is\nfound by the approach illustrated in the previous module, as shown here:\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["EXAMPLE 4.13\n"]]], "page_202": [["block_0", ["Using this theoretical yield and the provided value for actual yield, the percent yield is calculated to be\n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["What is the percent yield of a reaction that produces 12.5 g of the gas Freon CF2Cl2 from 32.9 g of CCl4 and\nexcess HF?\n"]], ["block_3", [" Answer: \n48.3%\n"]], ["block_4", [" Green Chemistry and Atom Economy \nThe purposeful design of chemical products and processes that minimize the use of environmentally\nhazardous substances and the generation of waste is known as green chemistry. Green chemistry is a\nphilosophical approach that is being applied to many areas of science and technology, and its practice is\nsummarized by guidelines known as the \u201cTwelve Principles of Green Chemistry\u201d (see details at this website\n(http://openstax.org/l/16greenchem)). One of the 12 principles is aimed specifically at maximizing the\nefficiency of processes for synthesizing chemical products. The atom economy of a process is a measure of this\nefficiency, defined as the percentage by mass of the final product of a synthesis relative to the masses of all the\nreactants used:\n"]], ["block_5", ["Though the definition of atom economy at first glance appears very similar to that for percent yield, be aware\nthat this property represents a difference in the theoretical efficiencies of different chemical processes. The\npercent yield of a given chemical process, on the other hand, evaluates the efficiency of a process by\ncomparing the yield of product actually obtained to the maximum yield predicted by stoichiometry.\n"]], ["block_6", ["The synthesis of the common nonprescription pain medication, ibuprofen, nicely illustrates the success of a\ngreen chemistry approach (Figure 4.15). First marketed in the early 1960s, ibuprofen was produced using a\nsix-step synthesis that required 514 g of reactants to generate each mole (206 g) of ibuprofen, an atom\neconomy of 40%. In the 1990s, an alternative process was developed by the BHC Company (now BASF\nCorporation) that requires only three steps and has an atom economy of ~80%, nearly twice that of the original\nprocess. The BHC process generates significantly less chemical waste; uses less-hazardous and recyclable\nmaterials; and provides significant cost-savings to the manufacturer (and, subsequently, the consumer). In\nrecognition of the positive environmental impact of the BHC process, the company received the Environmental\nProtection Agency\u2019s Greener Synthetic Pathways Award in 1997.\n"]], ["block_7", ["HOW SCIENCES INTERCONNECT\n"]], ["block_8", [" 4.4 \u2022 Reaction Yields \n 189 \n"]]], "page_203": [["block_0", [" 190 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", [" FIGURE 4.15 \n(a) Ibuprofen is a popular nonprescription pain medication commonly sold as 200 mg tablets. (b)\n"]], ["block_2", ["The BHC process for synthesizing ibuprofen requires only three steps and exhibits an impressive atom economy.\n(credit a: modification of work by Derrick Coetzee)\n"]], ["block_3", [" 4.5 Quantitative Chemical Analysis \n"]], ["block_4", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_5", ["In the 18th century, the strength (actually the concentration) of vinegar samples was determined by noting the\namount of potassium carbonate, K2CO3, which had to be added, a little at a time, before bubbling ceased. The\ngreater the weight of potassium carbonate added to reach the point where the bubbling ended, the more\nconcentrated the vinegar.\n"]], ["block_6", ["We now know that the effervescence that occurred during this process was due to reaction with acetic acid,\nCH3CO2H, the compound primarily responsible for the odor and taste of vinegar. Acetic acid reacts with\npotassium carbonate according to the following equation:\n"]], ["block_7", ["The bubbling was due to the production of CO2.\n"]], ["block_8", ["The test of vinegar with potassium carbonate is one type of quantitative analysis \u2014the determination of the\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["\u2022\nDescribe the fundamental aspects of titrations and gravimetric analysis.\n"]], ["block_11", ["\u2022\nPerform stoichiometric calculations using typical titration and gravimetric data.\n"]], ["block_12", [{"image_0": "203_0.png", "coords": [90, 57, 522, 439]}]]], "page_204": [["block_0", ["amount or concentration of a substance in a sample. In the analysis of vinegar, the concentration of the solute\n(acetic acid) was determined from the amount of reactant that combined with the solute present in a known\nvolume of the solution. In other types of chemical analyses, the amount of a substance present in a sample is\ndetermined by measuring the amount of product that results.\n"]], ["block_1", [" Titration \n"]], ["block_2", ["The described approach to measuring vinegar strength was an early version of the analytical technique known\nas titration analysis . A typical titration analysis involves the use of a buret (Figure 4.16) to make incremental\nadditions of a solution containing a known concentration of some substance (the titrant ) to a sample solution\ncontaining the substance whose concentration is to be measured (the analyte ). The titrant and analyte\nundergo a chemical reaction of known stoichiometry, and so measuring the volume of titrant solution required\nfor complete reaction with the analyte (the equivalence point of the titration) allows calculation of the analyte\nconcentration. The equivalence point of a titration may be detected visually if a distinct change in the\nappearance of the sample solution accompanies the completion of the reaction. The halt of bubble formation\nin the classic vinegar analysis is one such example, though, more commonly, special dyes called indicators are\nadded to the sample solutions to impart a change in color at or very near the equivalence point of the titration.\nEquivalence points may also be detected by measuring some solution property that changes in a predictable\nway during the course of the titration. Regardless of the approach taken to detect a titration\u2019s equivalence\npoint, the volume of titrant actually measured is called the end point . Properly designed titration methods\ntypically ensure that the difference between the equivalence and end points is negligible. Though any type of\nchemical reaction may serve as the basis for a titration analysis, the three described in this chapter\n(precipitation, acid-base, and redox) are most common. Additional details regarding titration analysis are\nprovided in the chapter on acid-base equilibria.\n"]], ["block_3", [" FIGURE 4.16 \n(a) A student fills a buret in preparation for a titration analysis. (b) A typical buret permits volume\n"]], ["block_4", ["measurements to the nearest 0.01 mL. (credit a: modification of work by Mark Blaser and Matt Evans; credit b:\nmodification of work by Mark Blaser and Matt Evans)\n"]], ["block_5", [{"image_0": "204_0.png", "coords": [130, 354, 481, 624]}]], ["block_6", [" 4.5 \u2022 Quantitative Chemical Analysis \n 191 \n"]]], "page_205": [["block_0", [" 192 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", [" Titration Analysis \n"]], ["block_2", ["The end point in a titration of a 50.00-mL sample of aqueous HCl was reached by addition of 35.23 mL of 0.250\nM NaOH titrant. The titration reaction is:\n"]], ["block_3", ["What is the molarity of the HCl?\n"]], ["block_4", [" Solution \n"]], ["block_5", ["As for all reaction stoichiometry calculations, the key issue is the relation between the molar amounts of the\nchemical species of interest as depicted in the balanced chemical equation. The approach outlined in previous\nmodules of this chapter is followed, with additional considerations required, since the amounts of reactants\nprovided and requested are expressed as solution concentrations.\n"]], ["block_6", ["For this exercise, the calculation will follow the following outlined steps:\n"]], ["block_7", [{"image_0": "205_0.png", "coords": [72, 264, 432, 424]}]], ["block_8", ["The molar amount of HCl is calculated to be:\n"]], ["block_9", ["Using the provided volume of HCl solution and the definition of molarity, the HCl concentration is:\n"]], ["block_10", ["Note: For these types of titration calculations, it is convenient to recognize that solution molarity is also equal\nto the number of millimoles of solute per milliliter of solution:\n"]], ["block_11", ["Using this version of the molarity unit will shorten the calculation by eliminating two conversion factors:\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["EXAMPLE 4.14\n"]]], "page_206": [["block_0", [" Check Your Learning \n"]], ["block_1", ["A 20.00-mL sample of aqueous oxalic acid, H2C2O4, was titrated with a 0.09113-M solution of potassium\npermanganate, KMnO4 (see net ionic equation below).\n"]], ["block_2", ["A volume of 23.24 mL was required to reach the end point. What is the oxalic acid molarity?\n"]], ["block_3", [" Answer: \n0.2648 M\n"]], ["block_4", [" Gravimetric Analysis \n"]], ["block_5", ["A gravimetric analysis is one in which a sample is subjected to some treatment that causes a change in the\nphysical state of the analyte that permits its separation from the other components of the sample. Mass\nmeasurements of the sample, the isolated analyte, or some other component of the analysis system, used\nalong with the known stoichiometry of the compounds involved, permit calculation of the analyte\nconcentration. Gravimetric methods were the first techniques used for quantitative chemical analysis, and\nthey remain important tools in the modern chemistry laboratory.\n"]], ["block_6", ["The required change of state in a gravimetric analysis may be achieved by various physical and chemical\nprocesses. For example, the moisture (water) content of a sample is routinely determined by measuring the\nmass of a sample before and after it is subjected to a controlled heating process that evaporates the water. Also\ncommon are gravimetric techniques in which the analyte is subjected to a precipitation reaction of the sort\ndescribed earlier in this chapter. The precipitate is typically isolated from the reaction mixture by filtration,\ncarefully dried, and then weighed (Figure 4.17). The mass of the precipitate may then be used, along with\nrelevant stoichiometric relationships, to calculate analyte concentration.\n"]], ["block_7", [" 4.5 \u2022 Quantitative Chemical Analysis \n 193 \n"]]], "page_207": [["block_0", [" 194 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", [" Gravimetric Analysis \n"]], ["block_2", ["A 0.4550-g solid mixture containing MgSO4 is dissolved in water and treated with an excess of Ba(NO3)2,\nresulting in the precipitation of 0.6168 g of BaSO4.\n"]], ["block_3", ["What is the concentration (mass percent) of MgSO4 in the mixture?\n"]], ["block_4", [" Solution \n"]], ["block_5", ["The plan for this calculation is similar to others used in stoichiometric calculations, the central step being the\nconnection between the moles of BaSO4 and MgSO4 through their stoichiometric factor. Once the mass of\nMgSO4 is computed, it may be used along with the mass of the sample mixture to calculate the requested\npercentage concentration.\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", ["EXAMPLE 4.15\n"]], ["block_8", [" FIGURE 4.17 \nPrecipitate may be removed from a reaction mixture by filtration.\n"]], ["block_9", [{"image_0": "207_0.png", "coords": [189, 57, 423, 436]}]]], "page_208": [["block_0", [{"image_0": "208_0.png", "coords": [72, 57, 432, 227]}]], ["block_1", ["The mass of MgSO4 that would yield the provided precipitate mass is\n"]], ["block_2", ["The concentration of MgSO4 in the sample mixture is then calculated to be\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["What is the percent of chloride ion in a sample if 1.1324 g of the sample produces 1.0881 g of AgCl when\ntreated with excess Ag?\n"]], ["block_5", [" Answer: \n23.76%\n"]], ["block_6", ["The elemental composition of hydrocarbons and related compounds may be determined via a gravimetric\nmethod known as combustion analysis . In a combustion analysis, a weighed sample of the compound is\nheated to a high temperature under a stream of oxygen gas, resulting in its complete combustion to yield\ngaseous products of known identities. The complete combustion of hydrocarbons, for example, will yield\ncarbon dioxide and water as the only products. The gaseous combustion products are swept through separate,\npreweighed collection devices containing compounds that selectively absorb each product (Figure 4.18). The\nmass increase of each device corresponds to the mass of the absorbed product and may be used in an\nappropriate stoichiometric calculation to derive the mass of the relevant element.\n"]], ["block_7", [{"image_1": "208_1.png", "coords": [72, 584, 540, 699]}]], ["block_8", [" FIGURE 4.18 \nThis schematic diagram illustrates the basic components of a combustion analysis device for\n"]], ["block_9", ["determining the carbon and hydrogen content of a sample.\n"]], ["block_10", [" 4.5 \u2022 Quantitative Chemical Analysis \n 195 \n"]]], "page_209": [["block_0", [" 196 \n 4 \u2022 Stoichiometry of Chemical Reactions \n"]], ["block_1", [" Combustion Analysis \n"]], ["block_2", ["Polyethylene is a hydrocarbon polymer used to produce food-storage bags and many other flexible plastic\nitems. A combustion analysis of a 0.00126-g sample of polyethylene yields 0.00394 g of CO2 and 0.00161 g of\nH2O. What is the empirical formula of polyethylene?\n"]], ["block_3", [" Solution \n"]], ["block_4", ["The primary assumption in this exercise is that all the carbon in the sample combusted is converted to carbon\ndioxide, and all the hydrogen in the sample is converted to water:\n"]], ["block_5", ["Note that a balanced equation is not necessary for the task at hand. To derive the empirical formula of the\ncompound, only the subscripts x and y are needed.\n"]], ["block_6", ["First, calculate the molar amounts of carbon and hydrogen in the sample, using the provided masses of the\ncarbon dioxide and water, respectively. With these molar amounts, the empirical formula for the compound\nmay be written as described in the previous chapter of this text. An outline of this approach is given in the\nfollowing flow chart:\n"]], ["block_7", [{"image_0": "209_0.png", "coords": [72, 311, 432, 582]}]], ["block_8", ["The empirical formula for the compound is then derived by identifying the smallest whole-number multiples\nfor these molar amounts. The H-to-C molar ratio is\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["EXAMPLE 4.16\n"]]], "page_210": [["block_0", ["and the empirical formula for polyethylene is CH2.\n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["A 0.00215-g sample of polystyrene, a polymer composed of carbon and hydrogen, produced 0.00726 g of CO2\nand 0.00148 g of H2O in a combustion analysis. What is the empirical formula for polystyrene?\n"]], ["block_3", [" Answer: \nCH\n"]], ["block_4", [" 4.5 \u2022 Quantitative Chemical Analysis \n 197 \n"]]], "page_211": [["block_0", [" 198 \n 4 \u2022 Key Terms \n"]], ["block_1", [" Key Terms \n"]], ["block_2", [" acid \nsubstance that produces H3Owhen dissolved\n"]], ["block_3", [" acid-base reaction \nreaction involving the transfer\n"]], ["block_4", [" actual yield \namount of product formed in a\n"]], ["block_5", [" analyte \nchemical species of interest\n"]], ["block_6", [" balanced equation \nchemical equation with equal\n"]], ["block_7", [" base \nsubstance that produces OHwhen dissolved\n"]], ["block_8", [" buret \ndevice used for the precise delivery of\n"]], ["block_9", [" chemical equation \nsymbolic representation of a\n"]], ["block_10", [" coefficient \nnumber placed in front of symbols or\n"]], ["block_11", [" combustion analysis \ngravimetric technique used\n"]], ["block_12", [" combustion reaction \nvigorous redox reaction\n"]], ["block_13", [" complete ionic equation \nchemical equation in\n"]], ["block_14", ["end point\nmeasured volume of titrant solution that\n"]], ["block_15", [" equivalence point \nvolume of titrant solution\n"]], ["block_16", [" excess reactant \nreactant present in an amount\n"]], ["block_17", [" gravimetric analysis \nquantitative chemical\n"]], ["block_18", [" half-reaction \nan equation that shows whether each\n"]], ["block_19", [" indicator \nsubstance added to the sample in a\n"]], ["block_20", [" Access for free at openstax.org \n"]], ["block_21", ["in water\n"]], ["block_22", ["of a hydrogen ion between reactant species\n"]], ["block_23", ["reaction\n"]], ["block_24", ["numbers of atoms for each element in the\nreactant and product\n"]], ["block_25", ["in water\n"]], ["block_26", ["variable liquid volumes, such as in a titration\nanalysis\n"]], ["block_27", ["chemical reaction\n"]], ["block_28", ["formulas in a chemical equation to indicate their\nrelative amount\n"]], ["block_29", ["to determine the elemental composition of a\ncompound via the collection and weighing of its\ngaseous combustion products\n"]], ["block_30", ["producing significant amounts of energy in the\nform of heat and, sometimes, light\n"]], ["block_31", ["which all dissolved ionic reactants and products,\nincluding spectator ions, are explicitly\nrepresented by formulas for their dissociated\nions\n"]], ["block_32", ["yields the change in sample solution appearance\nor other property expected for stoichiometric\nequivalence (see equivalence point)\n"]], ["block_33", ["required to react completely with the analyte in a\ntitration analysis; provides a stoichiometric\namount of titrant for the sample\u2019s analyte\naccording to the titration reaction\n"]], ["block_34", ["greater than required by the reaction\nstoichiometry\n"]], ["block_35", ["analysis method involving the separation of an\nanalyte from a sample by a physical or chemical\nprocess and subsequent mass measurements of\nthe analyte, reaction product, and/or sample\n"]], ["block_36", ["reactant loses or gains electrons in a reaction.\n"]], ["block_37", [" insoluble \nof relatively low solubility; dissolving\n"]], ["block_38", [" limiting reactant \nreactant present in an amount\n"]], ["block_39", [" molecular equation \nchemical equation in which\n"]], ["block_40", [" net ionic equation \nchemical equation in which\n"]], ["block_41", [" neutralization reaction \nreaction between an acid\n"]], ["block_42", [" oxidation \nprocess in which an element\u2019s oxidation \n"]], ["block_43", [" oxidation number \n(also, oxidation state) the\n"]], ["block_44", [" oxidation-reduction reaction \n(also, redox\n"]], ["block_45", [" oxidizing agent \n(also, oxidant) substance that\n"]], ["block_46", [" percent yield \nmeasure of the efficiency of a\n"]], ["block_47", [" precipitate \ninsoluble product that forms from\n"]], ["block_48", [" precipitation reaction \nreaction that produces one\n"]], ["block_49", [" product \nsubstance formed by a chemical or\n"]], ["block_50", [" quantitative analysis \nthe determination of the\n"]], ["block_51", [" reactant \nsubstance undergoing a chemical or\n"]], ["block_52", [" reducing agent \n(also, reductant) substance that\n"]], ["block_53", [" reduction \nprocess in which an element\u2019s oxidation\n"]], ["block_54", [" salt \nionic compound that can be formed by the\n"]], ["block_55", ["titration analysis to permit visual detection of the\nend point\n"]], ["block_56", ["only to a slight extent\n"]], ["block_57", ["lower than required by the reaction\nstoichiometry, thus limiting the amount of\nproduct generated\n"]], ["block_58", ["all reactants and products are represented as\nneutral substances\n"]], ["block_59", ["only those dissolved ionic reactants and products\nthat undergo a chemical or physical change are\nrepresented (excludes spectator ions)\n"]], ["block_60", ["and a base to produce salt and water\n"]], ["block_61", ["number is increased by loss of electrons\n"]], ["block_62", ["charge each atom of an element would have in a\ncompound if the compound were ionic\n"]], ["block_63", ["reaction) reaction involving a change in oxidation\nnumber for one or more reactant elements\n"]], ["block_64", ["brings about the oxidation of another substance,\nand in the process becomes reduced\n"]], ["block_65", ["reaction, expressed as a percentage of the\ntheoretical yield\n"]], ["block_66", ["reaction of soluble reactants\n"]], ["block_67", ["or more insoluble products; when reactants are\nionic compounds, sometimes called double-\ndisplacement or metathesis\n"]], ["block_68", ["physical change; shown on the right side of the\narrow in a chemical equation\n"]], ["block_69", ["amount or concentration of a substance in a\nsample\n"]], ["block_70", ["physical change; shown on the left side of the\narrow in a chemical equation\n"]], ["block_71", ["brings about the reduction of another substance,\nand in the process becomes oxidized\n"]], ["block_72", ["number is decreased by gain of electrons\n"]]], "page_212": [["block_0", [" single-displacement reaction \n(also, replacement)\n"]], ["block_1", [" solubility \nthe extent to which a substance may be\n"]], ["block_2", [" soluble \nof relatively high solubility; dissolving to a\n"]], ["block_3", [" spectator ion \nion that does not undergo a chemical\n"]], ["block_4", [" stoichiometric factor \nratio of coefficients in a\n"]], ["block_5", [" stoichiometry \nrelationships between the amounts\n"]], ["block_6", [" Key Equations \n"]], ["block_7", [" Summary \n"]], ["block_8", [" 4.1 Writing and Balancing Chemical \n Equations \n"]], ["block_9", ["Chemical equations are symbolic representations of\nchemical and physical changes. Formulas for the\nsubstances undergoing the change (reactants) and\nsubstances generated by the change (products) are\nseparated by an arrow and preceded by integer\ncoefficients indicating their relative numbers.\nBalanced equations are those whose coefficients\nresult in equal numbers of atoms for each element\nin the reactants and products. Chemical reactions in\naqueous solution that involve ionic reactants or\nproducts may be represented more realistically by\ncomplete ionic equations and, more succinctly, by\nnet ionic equations.\n"]], ["block_10", [" 4.2 Classifying Chemical Reactions \n"]], ["block_11", ["Chemical reactions are classified according to\nsimilar patterns of behavior. A large number of\nimportant reactions are included in three\ncategories: precipitation, acid-base, and oxidation-\nreduction (redox). Precipitation reactions involve\nthe formation of one or more insoluble products.\nAcid-base reactions involve the transfer of hydrogen\nions between reactants. Redox reactions involve a\nchange in oxidation number for one or more\nreactant elements. Writing balanced equations for\n"]], ["block_12", ["reaction of an acid with a base that contains a\ncation and an anion other than hydroxide or\noxide\n"]], ["block_13", ["redox reaction involving the oxidation of an\nelemental substance by an ionic species\n"]], ["block_14", ["dissolved in water, or any solvent\n"]], ["block_15", ["relatively large extent\n"]], ["block_16", ["or physical change during a reaction, but its\npresence is required to maintain charge\nneutrality\n"]], ["block_17", ["balanced chemical equation, used in\ncomputations relating amounts of reactants and\nproducts\n"]], ["block_18", [" strong acid \nacid that reacts completely when\n"]], ["block_19", [" strong base \nbase that reacts completely when\n"]], ["block_20", [" theoretical yield \namount of product that may be\n"]], ["block_21", [" titrant \nsolution containing a known concentration\n"]], ["block_22", [" titration analysis \nquantitative chemical analysis\n"]], ["block_23", [" weak acid \nacid that reacts only to a slight extent\n"]], ["block_24", [" weak base \nbase that reacts only to a slight extent\n"]], ["block_25", ["some redox reactions that occur in aqueous\nsolutions is simplified by using a systematic\napproach called the half-reaction method.\n"]], ["block_26", [" 4.3 Reaction Stoichiometry \n"]], ["block_27", ["A balanced chemical equation may be used to\ndescribe a reaction\u2019s stoichiometry (the\nrelationships between amounts of reactants and\nproducts). Coefficients from the equation are used to\nderive stoichiometric factors that subsequently may\nbe used for computations relating reactant and\nproduct masses, molar amounts, and other\nquantitative properties.\n"]], ["block_28", [" 4.4 Reaction Yields \n"]], ["block_29", ["When reactions are carried out using less-than-\nstoichiometric quantities of reactants, the amount of\nproduct generated will be determined by the\nlimiting reactant. The amount of product generated\nby a chemical reaction is its actual yield. This yield\nis often less than the amount of product predicted by\nthe stoichiometry of the balanced chemical equation\nrepresenting the reaction (its theoretical yield). The\nextent to which a reaction generates the theoretical\namount of product is expressed as its percent yield.\n"]], ["block_30", ["of reactants and products of a chemical reaction\n"]], ["block_31", ["dissolved in water to yield hydronium ions\n"]], ["block_32", ["dissolved in water to yield hydroxide ions\n"]], ["block_33", ["produced from a given amount of reactant(s)\naccording to the reaction stoichiometry\n"]], ["block_34", ["of substance that will react with the analyte in a\n titration analysis \n"]], ["block_35", ["method that involves measuring the volume of a\nreactant solution required to completely react\nwith the analyte in a sample\n"]], ["block_36", ["when dissolved in water to yield hydronium ions\n"]], ["block_37", ["when dissolved in water to yield hydroxide ions\n"]], ["block_38", [" 4 \u2022 Key Equations \n 199 \n"]]], "page_213": [["block_0", [" 200 \n 4 \u2022 Exercises \n"]], ["block_1", [" 4.5 Quantitative Chemical Analysis \n"]], ["block_2", ["The stoichiometry of chemical reactions may serve\nas the basis for quantitative chemical analysis\nmethods. Titrations involve measuring the volume\nof a titrant solution required to completely react\nwith a sample solution. This volume is then used to\ncalculate the concentration of analyte in the sample\nusing the stoichiometry of the titration reaction.\nGravimetric analysis involves separating the analyte\n"]], ["block_3", [" Exercises \n"]], ["block_4", [" 4.1 Writing and Balancing Chemical Equations \n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", [" 1 . What does it mean to say an equation is balanced? Why is it important for an equation to be balanced?\n 2 . Consider molecular, complete ionic, and net ionic equations.\n"]], ["block_7", [" 3 . Balance the following equations:\n"]], ["block_8", [" 4 . Balance the following equations:\n"]], ["block_9", [" 5 . Write a balanced molecular equation describing each of the following chemical reactions.\n"]], ["block_10", [" 6 . Write a balanced equation describing each of the following chemical reactions.\n"]], ["block_11", ["(a) What is the difference between these types of equations?\n(b) In what circumstance would the complete and net ionic equations for a reaction be identical?\n"]], ["block_12", ["(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n(g)\n(h)\n"]], ["block_13", ["(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n(g)\n(h)\n"]], ["block_14", ["(a) Solid calcium carbonate is heated and decomposes to solid calcium oxide and carbon dioxide gas.\n(b) Gaseous butane, C4H10, reacts with diatomic oxygen gas to yield gaseous carbon dioxide and water\nvapor.\n(c) Aqueous solutions of magnesium chloride and sodium hydroxide react to produce solid magnesium\nhydroxide and aqueous sodium chloride.\n(d) Water vapor reacts with sodium metal to produce solid sodium hydroxide and hydrogen gas.\n"]], ["block_15", ["(a) Solid potassium chlorate, KClO3, decomposes to form solid potassium chloride and diatomic oxygen\ngas.\n(b) Solid aluminum metal reacts with solid diatomic iodine to form solid Al2I6.\n(c) When solid sodium chloride is added to aqueous sulfuric acid, hydrogen chloride gas and aqueous\nsodium sulfate are produced.\n(d) Aqueous solutions of phosphoric acid and potassium hydroxide react to produce aqueous potassium\ndihydrogen phosphate and liquid water.\n"]], ["block_16", ["from the sample by a physical or chemical process,\ndetermining its mass, and then calculating its\nconcentration in the sample based on the\nstoichiometry of the relevant process. Combustion\nanalysis is a gravimetric method used to determine\nthe elemental composition of a compound by\ncollecting and weighing the gaseous products of its\ncombustion.\n"]]], "page_214": [["block_0", [" 8 . Fill in the blank with a single chemical formula for a covalent compound that will balance the equation:\n"]], ["block_1", [" 10 . A novel process for obtaining magnesium from sea water involves several reactions. Write a balanced\n"]], ["block_2", [" 11 . From the balanced molecular equations, write the complete ionic and net ionic equations for the\n"]], ["block_3", [" 4.2 Classifying Chemical Reactions \n"]], ["block_4", [" 12 . Use the following equations to answer the next four questions:\n"]], ["block_5", [" 7 . Colorful fireworks often involve the decomposition of barium nitrate and potassium chlorate and the\n"]], ["block_6", [" 9 . Aqueous hydrogen fluoride (hydrofluoric acid) is used to etch glass and to analyze minerals for their\n"]], ["block_7", [{"image_0": "214_0.png", "coords": [85, 183, 553, 234]}]], ["block_8", ["reaction of the metals magnesium, aluminum, and iron with oxygen.\n(a) Write the formulas of barium nitrate and potassium chlorate.\n(b) The decomposition of solid potassium chlorate leads to the formation of solid potassium chloride and\ndiatomic oxygen gas. Write an equation for the reaction.\n(c) The decomposition of solid barium nitrate leads to the formation of solid barium oxide, diatomic\nnitrogen gas, and diatomic oxygen gas. Write an equation for the reaction.\n(d) Write separate equations for the reactions of the solid metals magnesium, aluminum, and iron with\ndiatomic oxygen gas to yield the corresponding metal oxides. (Assume the iron oxide contains Feions.)\n"]], ["block_9", ["silicon content. Hydrogen fluoride will also react with sand (silicon dioxide).\n(a) Write an equation for the reaction of solid silicon dioxide with hydrofluoric acid to yield gaseous silicon\ntetrafluoride and liquid water.\n(b) The mineral fluorite (calcium fluoride) occurs extensively in Illinois. Solid calcium fluoride can also be\nprepared by the reaction of aqueous solutions of calcium chloride and sodium fluoride, yielding aqueous\nsodium chloride as the other product. Write complete and net ionic equations for this reaction.\n"]], ["block_10", ["chemical equation for each step of the process.\n(a) The first step is the decomposition of solid calcium carbonate from seashells to form solid calcium\noxide and gaseous carbon dioxide.\n(b) The second step is the formation of solid calcium hydroxide as the only product from the reaction of\nthe solid calcium oxide with liquid water.\n(c) Solid calcium hydroxide is then added to the seawater, reacting with dissolved magnesium chloride to\nyield solid magnesium hydroxide and aqueous calcium chloride.\n(d) The solid magnesium hydroxide is added to a hydrochloric acid solution, producing dissolved\nmagnesium chloride and liquid water.\n(e) Finally, the magnesium chloride is melted and electrolyzed to yield liquid magnesium metal and\ndiatomic chlorine gas.\n"]], ["block_11", ["following:\n(a)\n(b)\n(c)\n"]], ["block_12", ["i.\nii.\niii.\niv.\nv.\n(a) Which equation describes a physical change?\n(b) Which equation identifies the reactants and products of a combustion reaction?\n(c) Which equation is not balanced?\n(d) Which is a net ionic equation?\n"]], ["block_13", [" 4 \u2022 Exercises \n 201 \n"]]], "page_215": [["block_0", [" 202 \n 4 \u2022 Exercises \n"]], ["block_1", [" 13 . Indicate what type, or types, of reaction each of the following represents:\n"]], ["block_2", [" 14 . Indicate what type, or types, of reaction each of the following represents:\n"]], ["block_3", [" 15 . Silver can be separated from gold because silver dissolves in nitric acid while gold does not. Is the\n"]], ["block_4", [" 16 . Determine the oxidation states of the elements in the following compounds:\n"]], ["block_5", [" 17 . Determine the oxidation states of the elements in the compounds listed. None of the oxygen-containing\n"]], ["block_6", [" 18 . Determine the oxidation states of the elements in the compounds listed. None of the oxygen-containing\n"]], ["block_7", [" 19 . Classify the following as acid-base reactions or oxidation-reduction reactions:\n"]], ["block_8", [" 20 . Identify the atoms that are oxidized and reduced, the change in oxidation state for each, and the oxidizing\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["(a)\n(b)\n(c)\n"]], ["block_11", ["(a)\n(b)\n(c)\n(d)\n"]], ["block_12", ["dissolution of silver in nitric acid an acid-base reaction or an oxidation-reduction reaction? Explain your\nanswer.\n"]], ["block_13", ["(a) NaI\n(b) GdCl3\n(c) LiNO3\n(d) H2Se\n(e) Mg2Si\n(f) RbO2, rubidium superoxide\n(g) HF\n"]], ["block_14", ["compounds are peroxides or superoxides.\n(a) H3PO4\n(b) Al(OH)3\n(c) SeO2\n(d) KNO2\n(e) In2S3\n(f) P4O6\n"]], ["block_15", ["compounds are peroxides or superoxides.\n(a) H2SO4\n(b) Ca(OH)2\n(c) BrOH\n(d) ClNO2\n(e) TiCl4\n(f) NaH\n"]], ["block_16", ["(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n"]], ["block_17", ["and reducing agents in each of the following equations:\n(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n"]]], "page_216": [["block_0", [" 21 . Complete and balance the following acid-base equations:\n"]], ["block_1", [" 22 . Complete and balance the following acid-base equations:\n"]], ["block_2", [" 23 . Complete and balance the following oxidation-reduction reactions, which give the highest possible\n"]], ["block_3", [" 24 . Complete and balance the following oxidation-reduction reactions, which give the highest possible\n"]], ["block_4", [" 25 . Complete and balance the equations for the following acid-base neutralization reactions. If water is used\n"]], ["block_5", [" 26 . When heated to 700\u2013800 \u00b0C, diamonds, which are pure carbon, are oxidized by atmospheric oxygen.\n"]], ["block_6", [" 27 . The military has experimented with lasers that produce very intense light when fluorine combines\n"]], ["block_7", [" 28 . Write the molecular, total ionic, and net ionic equations for the following reactions:\n"]], ["block_8", [" 29 . Great Lakes Chemical Company produces bromine, Br2, from bromide salts such as NaBr, in Arkansas\n"]], ["block_9", [" 30 . In a common experiment in the general chemistry laboratory, magnesium metal is heated in air to\n"]], ["block_10", [" 31 . Lithium hydroxide may be used to absorb carbon dioxide in enclosed environments, such as manned\n"]], ["block_11", [" 32 . Calcium propionate is sometimes added to bread to retard spoilage. This compound can be prepared by\n"]], ["block_12", [" 33 . Complete and balance the equations of the following reactions, each of which could be used to remove\n"]], ["block_13", [" 34 . Copper(II) sulfide is oxidized by molecular oxygen to produce gaseous sulfur trioxide and solid copper(II)\n"]], ["block_14", ["(a) HCl gas reacts with solid Ca(OH)2(s).\n(b) A solution of Sr(OH)2 is added to a solution of HNO3.\n"]], ["block_15", ["(a) A solution of HClO4 is added to a solution of LiOH.\n(b) Aqueous H2SO4 reacts with NaOH.\n(c) Ba(OH)2 reacts with HF gas.\n"]], ["block_16", ["oxidation state for the oxidized atoms.\n(a)\n(b)\n(single displacement)\n"]], ["block_17", ["(c)\n(d)\n(products are a strong base and a diatomic gas)\n"]], ["block_18", ["oxidation state for the oxidized atoms.\n(a)\n(b)\n(c)\n"]], ["block_19", ["as a solvent, write the reactants and products as aqueous ions. In some cases, there may be more than one\ncorrect answer, depending on the amounts of reactants used.\n(a)\n(b)\n(c)\n"]], ["block_20", ["(They burn!) Write the balanced equation for this reaction.\n"]], ["block_21", ["explosively with hydrogen. What is the balanced equation for this reaction?\n"]], ["block_22", ["(a)\n(b)\n"]], ["block_23", ["brine by treating the brine with chlorine gas. Write a balanced equation for the reaction of NaBr with Cl2.\n"]], ["block_24", ["produce MgO. MgO is a white solid, but in these experiments it often looks gray, due to small amounts of\nMg3N2, a compound formed as some of the magnesium reacts with nitrogen. Write a balanced equation\nfor each reaction.\n"]], ["block_25", ["spacecraft and submarines. Write an equation for the reaction that involves 2 mol of LiOH per 1 mol of\nCO2. (Hint: Water is one of the products.)\n"]], ["block_26", ["the reaction of calcium carbonate, CaCO3, with propionic acid, C2H5CO2H, which has properties similar to\nthose of acetic acid. Write the balanced equation for the formation of calcium propionate.\n"]], ["block_27", ["hydrogen sulfide from natural gas:\n(a)\n(b)\n"]], ["block_28", ["oxide. The gaseous product then reacts with liquid water to produce liquid dihydrogen sulfate as the only\nproduct. Write the two equations which represent these reactions.\n"]], ["block_29", [" 4 \u2022 Exercises \n 203 \n"]]], "page_217": [["block_0", [" 204 \n 4 \u2022 Exercises \n"]], ["block_1", [" 35 . Write balanced chemical equations for the reactions used to prepare each of the following compounds\n"]], ["block_2", [" 36 . Calcium cyclamate Ca(C6H11NHSO3)2 is an artificial sweetener used in many countries around the world\n"]], ["block_3", [" 37 . Complete and balance each of the following half-reactions (steps 2\u20135 in half-reaction method):\n"]], ["block_4", [" 38 . Complete and balance each of the following half-reactions (steps 2\u20135 in half-reaction method):\n"]], ["block_5", [" 39 . Balance each of the following equations according to the half-reaction method:\n"]], ["block_6", [" 40 . Balance each of the following equations according to the half-reaction method:\n"]], ["block_7", [" 41 . Balance each of the following equations according to the half-reaction method:\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["from the given starting material(s). In some cases, additional reactants may be required.\n(a) solid ammonium nitrate from gaseous molecular nitrogen via a two-step process (first reduce the\nnitrogen to ammonia, then neutralize the ammonia with an appropriate acid)\n(b) gaseous hydrogen bromide from liquid molecular bromine via a one-step redox reaction\n(c) gaseous H2S from solid Zn and S via a two-step process (first a redox reaction between the starting\nmaterials, then reaction of the product with a strong acid)\n"]], ["block_10", ["but is banned in the United States. It can be purified industrially by converting it to the barium salt\nthrough reaction of the acid C6H11NHSO3H with barium carbonate, treatment with sulfuric acid (barium\nsulfate is very insoluble), and then neutralization with calcium hydroxide. Write the balanced equations\nfor these reactions.\n"]], ["block_11", ["(a)\n"]], ["block_12", ["(b)\n"]], ["block_13", ["(c)\n(d)\n(in acidic solution)\n"]], ["block_14", ["(e)\n(in basic solution)\n"]], ["block_15", ["(f)\n(in acidic solution)\n"]], ["block_16", ["(g)\n(in acidic solution)\n"]], ["block_17", ["(h)\n(in basic solution)\n"]], ["block_18", ["(a)\n(b)\n"]], ["block_19", ["(c)\n(d)\n(in basic solution)\n"]], ["block_20", ["(e)\n(in acidic solution)\n"]], ["block_21", ["(f)\n(in acidic solution)\n"]], ["block_22", ["(g)\n(in basic solution)\n"]], ["block_23", ["(h)\n(in acidic solution)\n"]], ["block_24", ["(a)\n(b)\n(c)\n(d)\n(e)\n"]], ["block_25", ["(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n(g)\n"]], ["block_26", ["(a)\n(b)\n(c)\n"]]], "page_218": [["block_0", [" 4.3 Reaction Stoichiometry \n"]], ["block_1", [" 42 . Write the balanced equation, then outline the steps necessary to determine the information requested in each\n"]], ["block_2", [" 43 . Determine the number of moles and the mass requested for each reaction in Exercise 4.42.\n 44 . Write the balanced equation, then outline the steps necessary to determine the information requested in each\n"]], ["block_3", [" 45 . Determine the number of moles and the mass requested for each reaction in Exercise 4.44.\n 46 . H2 is produced by the reaction of 118.5 mL of a 0.8775-M solution of H3PO4 according to the following\n"]], ["block_4", [" 47 . Gallium chloride is formed by the reaction of 2.6 L of a 1.44 M solution of HCl according to the following\n"]], ["block_5", [" 48 . I2 is produced by the reaction of 0.4235 mol of CuCl2 according to the following equation:\n"]], ["block_6", [" 49 . Silver is often extracted from ores such as K[Ag(CN)2] and then recovered by the reaction\n"]], ["block_7", ["of the following:\n(a) The number of moles and the mass of chlorine, Cl2, required to react with 10.0 g of sodium metal, Na, to\nproduce sodium chloride, NaCl.\n(b) The number of moles and the mass of oxygen formed by the decomposition of 1.252 g of mercury(II) oxide.\n(c) The number of moles and the mass of sodium nitrate, NaNO3, required to produce 128 g of oxygen. (NaNO2\nis the other product.)\n(d) The number of moles and the mass of carbon dioxide formed by the combustion of 20.0 kg of carbon in an\nexcess of oxygen.\n(e) The number of moles and the mass of copper(II) carbonate needed to produce 1.500 kg of copper(II) oxide.\n(CO2 is the other product.)\n(f)\n"]], ["block_8", [{"image_0": "218_0.png", "coords": [91, 228, 559, 298]}]], ["block_9", ["of the following:\n(a) The number of moles and the mass of Mg required to react with 5.00 g of HCl and produce MgCl2 and H2.\n(b) The number of moles and the mass of oxygen formed by the decomposition of 1.252 g of silver(I) oxide.\n(c) The number of moles and the mass of magnesium carbonate, MgCO3, required to produce 283 g of carbon\ndioxide. (MgO is the other product.)\n(d) The number of moles and the mass of water formed by the combustion of 20.0 kg of acetylene, C2H2, in an\nexcess of oxygen.\n(e) The number of moles and the mass of barium peroxide, BaO2, needed to produce 2.500 kg of barium oxide,\nBaO (O2 is the other product.)\n(f)\n"]], ["block_10", [{"image_1": "218_1.png", "coords": [91, 452, 559, 503]}]], ["block_11", ["equation:\n(a) Outline the steps necessary to determine the number of moles and mass of H2.\n(b) Perform the calculations outlined.\n"]], ["block_12", ["equation:\n(a) Outline the steps necessary to determine the number of moles and mass of gallium chloride.\n(b) Perform the calculations outlined.\n"]], ["block_13", ["(a) How many molecules of I2 are produced?\n(b) What mass of I2 is produced?\n"]], ["block_14", ["(a) How many molecules of Zn(CN)2 are produced by the reaction of 35.27 g of K[Ag(CN)2]?\n(b) What mass of Zn(CN)2 is produced?\n"]], ["block_15", [" 4 \u2022 Exercises \n 205 \n"]]], "page_219": [["block_0", [" 206 \n 4 \u2022 Exercises \n"]], ["block_1", [" 50 . What mass of silver oxide, Ag2O, is required to produce 25.0 g of silver sulfadiazine, AgC10H9N4SO2, from\n"]], ["block_2", [" 51 . Carborundum is silicon carbide, SiC, a very hard material used as an abrasive on sandpaper and in other\n"]], ["block_3", [" 52 . Automotive air bags inflate when a sample of sodium azide, NaN3, is very rapidly decomposed.\n"]], ["block_4", [" 53 . Urea, CO(NH2)2, is manufactured on a large scale for use in producing urea-formaldehyde plastics and as\n"]], ["block_5", [" 54 . In an accident, a solution containing 2.5 kg of nitric acid was spilled. Two kilograms of Na2CO3 was quickly\n"]], ["block_6", [" 55 . A compact car gets 37.5 miles per gallon on the highway. If gasoline contains 84.2% carbon by mass and\n"]], ["block_7", [" 56 . What volume of 0.750 M hydrochloric acid solution can be prepared from the HCl produced by the\n"]], ["block_8", [" 57 . What volume of a 0.2089 M KI solution contains enough KI to react exactly with the Cu(NO3)2 in 43.88 mL\n"]], ["block_9", [" 58 . A mordant is a substance that combines with a dye to produce a stable fixed color in a dyed fabric. Calcium\n"]], ["block_10", [" 59 . The toxic pigment called white lead, Pb3(OH)2(CO3)2, has been replaced in white paints by rutile, TiO2.\n"]], ["block_11", [" 4.4 Reaction Yields \n"]], ["block_12", [" 60 . The following quantities are placed in a container: 1.5\n10atoms of hydrogen, 1.0 mol of sulfur, and\n"]], ["block_13", [" 61 . What is the limiting reactant in a reaction that produces sodium chloride from 8 g of sodium and 8 g of\n"]], ["block_14", [" 62 . Which of the postulates of Dalton's atomic theory explains why we can calculate a theoretical yield for a\n"]], ["block_15", [" 63 . A student isolated 25 g of a compound following a procedure that would theoretically yield 81 g. What was\n"]], ["block_16", [" 64 . A sample of 0.53 g of carbon dioxide was obtained by heating 1.31 g of calcium carbonate. What is the\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["the reaction of silver oxide and sulfadiazine?\n"]], ["block_19", ["applications. It is prepared by the reaction of pure sand, SiO2, with carbon at high temperature. Carbon\nmonoxide, CO, is the other product of this reaction. Write the balanced equation for the reaction, and\ncalculate how much SiO2 is required to produce 3.00 kg of SiC.\n"]], ["block_20", ["What mass of sodium azide is required to produce 2.6 ft(73.6 L) of nitrogen gas with a density of 1.25 g/\nL?\n"]], ["block_21", ["a fertilizer. What is the maximum mass of urea that can be manufactured from the CO2 produced by\ncombustion of\nof carbon followed by the reaction?\n"]], ["block_22", ["spread on the area and CO2 was released by the reaction. Was sufficient Na2CO3 used to neutralize all of\nthe acid?\n"]], ["block_23", ["has a density of 0.8205 g/mL, determine the mass of carbon dioxide produced during a 500-mile trip\n(3.785 liters per gallon).\n"]], ["block_24", ["reaction of 25.0 g of NaCl with excess sulfuric acid?\n"]], ["block_25", ["of a 0.3842 M solution of Cu(NO3)2?\n"]], ["block_26", ["acetate is used as a mordant. It is prepared by the reaction of acetic acid with calcium hydroxide.\n"]], ["block_27", ["What mass of Ca(OH)2 is required to react with the acetic acid in 25.0 mL of a solution having a density of\n1.065 g/mL and containing 58.0% acetic acid by mass?\n"]], ["block_28", ["How much rutile (g) can be prepared from 379 g of an ore that contains 88.3% ilmenite (FeTiO3) by mass?\n"]], ["block_29", ["88.0 g of diatomic oxygen.\n(a) What is the total mass in grams for the collection of all three elements?\n(b) What is the total number of moles of atoms for the three elements?\n(c) If the mixture of the three elements formed a compound with molecules that contain two hydrogen\natoms, one sulfur atom, and four oxygen atoms, which substance is consumed first?\n(d) How many atoms of each remaining element would remain unreacted in the change described in (c)?\n"]], ["block_30", ["diatomic chlorine?\n"]], ["block_31", ["chemical reaction?\n"]], ["block_32", ["his percent yield?\n"]], ["block_33", ["percent yield for this reaction?\n"]]], "page_220": [["block_0", [" 65 . Freon-12, CCl2F2, is prepared from CCl4 by reaction with HF. The other product of this reaction is HCl.\n"]], ["block_1", [" 66 . Citric acid, C6H8O7, a component of jams, jellies, and fruity soft drinks, is prepared industrially via\n"]], ["block_2", [" 67 . Toluene, C6H5CH3, is oxidized by air under carefully controlled conditions to benzoic acid, C6H5CO2H,\n"]], ["block_3", [" 68 . In a laboratory experiment, the reaction of 3.0 mol of H2 with 2.0 mol of I2 produced 1.0 mol of HI.\n"]], ["block_4", [" 69 . Outline the steps needed to solve the following problem, then do the calculations. Ether, (C2H5)2O, which\n"]], ["block_5", [" 70 . Outline the steps needed to determine the limiting reactant when 30.0 g of propane, C3H8, is burned with\n"]], ["block_6", [" 71 . Outline the steps needed to determine the limiting reactant when 0.50 mol of Cr and 0.75 mol of H3PO4\n"]], ["block_7", [" 72 . What is the limiting reactant when 1.50 g of lithium and 1.50 g of nitrogen combine to form lithium\n"]], ["block_8", [" 73 . Uranium can be isolated from its ores by dissolving it as UO2(NO3)2, then separating it as solid\n"]], ["block_9", [" 74 . How many molecules of C2H4Cl2 can be prepared from 15 C2H4 molecules and 8 Cl2 molecules?\n 75 . How many molecules of the sweetener saccharin can be prepared from 30 C atoms, 25 H atoms, 12 O\n"]], ["block_10", [" 76 . The phosphorus pentoxide used to produce phosphoric acid for cola soft drinks is prepared by burning\n"]], ["block_11", ["Outline the steps needed to determine the percent yield of a reaction that produces 12.5 g of CCl2F2 from\n32.9 g of CCl4. Freon-12 has been banned and is no longer used as a refrigerant because it catalyzes the\ndecomposition of ozone and has a very long lifetime in the atmosphere. Determine the percent yield.\n"]], ["block_12", ["fermentation of sucrose by the mold Aspergillus niger. The equation representing this reaction is\n"]], ["block_13", ["What mass of citric acid is produced from exactly 1 metric ton (1.000\n10kg) of sucrose if the yield is\n"]], ["block_14", ["92.30%?\n"]], ["block_15", ["which is used to prepare the food preservative sodium benzoate, C6H5CO2Na. What is the percent yield of\na reaction that converts 1.000 kg of toluene to 1.21 kg of benzoic acid?\n"]], ["block_16", ["Determine the theoretical yield in grams and the percent yield for this reaction.\n"]], ["block_17", ["was originally used as an anesthetic but has been replaced by safer and more effective medications, is\nprepared by the reaction of ethanol with sulfuric acid.\n2C2H5OH + H2SO4 \u27f6 (C2H5)2O + H2SO4\u00b7H2O\nWhat is the percent yield of ether if 1.17 L (d = 0.7134 g/mL) is isolated from the reaction of 1.500 L of\nC2H5OH\n(d = 0.7894 g/mL)?\n"]], ["block_18", ["75.0 g of oxygen.\nDetermine the limiting reactant.\n"]], ["block_19", ["react according to the following chemical equation.\n"]], ["block_20", ["Determine the limiting reactant.\n"]], ["block_21", ["nitride, a component of advanced batteries, according to the following unbalanced equation?\n"]], ["block_22", ["UO2(C2O4)\u00b73H2O. Addition of 0.4031 g of sodium oxalate, Na2C2O4, to a solution containing 1.481 g of\nuranyl nitrate, UO2(NO3)2, yields 1.073 g of solid UO2(C2O4)\u00b73H2O.\nNa2C2O4 + UO2(NO3)2 + 3H2O \u27f6 UO2(C2O4)\u00b73H2O + 2NaNO3\nDetermine the limiting reactant and the percent yield of this reaction.\n"]], ["block_23", ["atoms, 8 S atoms, and 14 N atoms?\n"]], ["block_24", [{"image_0": "220_0.png", "coords": [91, 561, 208, 653]}]], ["block_25", ["phosphorus in oxygen.\n(a) What is the limiting reactant when 0.200 mol of P4 and 0.200 mol of O2 react according to\n"]], ["block_26", ["(b) Calculate the percent yield if 10.0 g of P4O10 is isolated from the reaction.\n"]], ["block_27", [" 4 \u2022 Exercises \n 207 \n"]]], "page_221": [["block_0", [" 208 \n 4 \u2022 Exercises \n"]], ["block_1", [" 77 . Would you agree to buy 1 trillion (1,000,000,000,000) gold atoms for $5? Explain why or why not. Find the\n"]], ["block_2", [" 4.5 Quantitative Chemical Analysis \n"]], ["block_3", [" 78 . What volume of 0.0105-M HBr solution is required to titrate 125 mL of a 0.0100-M Ca(OH)2 solution?\n"]], ["block_4", [" 79 . Titration of a 20.0-mL sample of acid rain required 1.7 mL of 0.0811 M NaOH to reach the end point. If we\n"]], ["block_5", [" 80 . What is the concentration of NaCl in a solution if titration of 15.00 mL of the solution with 0.2503 M AgNO3\n"]], ["block_6", [" 81 . In a common medical laboratory determination of the concentration of free chloride ion in blood serum, a\n"]], ["block_7", [" 82 . Potatoes can be peeled commercially by soaking them in a 3-M to 6-M solution of sodium hydroxide, then\n"]], ["block_8", [" 83 . A sample of gallium bromide, GaBr3, weighing 0.165 g was dissolved in water and treated with silver\n"]], ["block_9", [" 84 . The principal component of mothballs is naphthalene, a compound with a molecular mass of about 130\n"]], ["block_10", [" 85 . A 0.025-g sample of a compound composed of boron and hydrogen, with a molecular mass of ~28 amu,\n"]], ["block_11", [" 86 . Sodium bicarbonate (baking soda), NaHCO3, can be purified by dissolving it in hot water (60 \u00b0C), filtering\n"]], ["block_12", [" 87 . What volume of 0.600 M HCl is required to react completely with 2.50 g of sodium hydrogen carbonate?\n"]], ["block_13", [" 88 . What volume of 0.08892 M HNO3 is required to react completely with 0.2352 g of potassium hydrogen\n"]], ["block_14", [" 89 . What volume of a 0.3300-M solution of sodium hydroxide would be required to titrate 15.00 mL of 0.1500\n"]], ["block_15", [" 90 . What volume of a 0.00945-M solution of potassium hydroxide would be required to titrate 50.00 mL of a\n"]], ["block_16", [" 91 . A sample of solid calcium hydroxide, Ca(OH)2, is allowed to stand in water until a saturated solution is\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["M Hg(NO3)2(aq) to reach the end point?\n"]], ["block_19", ["M oxalic acid?\n"]], ["block_20", ["current price of gold at http://money.cnn.com/data/commodities/\n"]], ["block_21", ["assume that the acidity of the rain is due to the presence of sulfuric acid, what was the concentration of\nsulfuric acid in this sample of rain?\n"]], ["block_22", ["requires 20.22 mL of the AgNO3 solution to reach the end point?\n"]], ["block_23", ["serum sample is titrated with a Hg(NO3)2 solution.\n"]], ["block_24", ["What is the Clconcentration in a 0.25-mL sample of normal serum that requires 1.46 mL of 8.25\n10\n"]], ["block_25", ["removing the loosened skins by spraying them with water. Does a sodium hydroxide solution have a\nsuitable concentration if titration of 12.00 mL of the solution requires 30.6 mL of 1.65 M HCI to reach the\nend point?\n"]], ["block_26", ["nitrate, AgNO3, resulting in the precipitation of 0.299 g AgBr. Use these data to compute the %Ga (by mass)\nGaBr3.\n"]], ["block_27", ["amu, containing only carbon and hydrogen. A 3.000-mg sample of naphthalene burns to give 10.3 mg of\nCO2. Determine its empirical and molecular formulas.\n"]], ["block_28", ["burns spontaneously when exposed to air, producing 0.063 g of B2O3. What are the empirical and\nmolecular formulas of the compound?\n"]], ["block_29", ["to remove insoluble impurities, cooling to 0 \u00b0C to precipitate solid NaHCO3, and then filtering to remove\nthe solid, leaving soluble impurities in solution. Any NaHCO3 that remains in solution is not recovered.\nThe solubility of NaHCO3 in hot water of 60 \u00b0C is 164 g/L. Its solubility in cold water of 0 \u00b0C is 69 g/L. What\nis the percent yield of NaHCO3 when it is purified by this method?\n"]], ["block_30", ["phosphate?\n"]], ["block_31", ["sample of acid rain with a H2SO4 concentration of 1.23\n10M.\n"]], ["block_32", ["formed. A titration of 75.00 mL of this solution with 5.00\n10M HCl requires 36.6 mL of the acid to\n"]], ["block_33", ["reach the end point.\n"]], ["block_34", ["What is the molarity?\n"]]], "page_222": [["block_0", [" 92 . What mass of Ca(OH)2 will react with 25.0 g of butanoic to form the preservative calcium butanoate\n"]], ["block_1", [" 93 . How many milliliters of a 0.1500-M solution of KOH will be required to titrate 40.00 mL of a 0.0656-M\n"]], ["block_2", [" 94 . Potassium hydrogen phthalate, KHC8H4O4, or KHP, is used in many laboratories, including general\n"]], ["block_3", [" 95 . The reaction of WCl6 with Al at ~400 \u00b0C gives black crystals of a compound containing only tungsten and\n"]], ["block_4", ["according to the equation?\n"]], ["block_5", [{"image_0": "222_0.png", "coords": [91, 82, 528, 139]}]], ["block_6", ["solution of H3PO4?\n"]], ["block_7", ["chemistry laboratories, to standardize solutions of base. KHP is one of only a few stable solid acids that\ncan be dried by warming and weighed. A 0.3420-g sample of KHC8H4O4 reacts with 35.73 mL of a NaOH\nsolution in a titration. What is the molar concentration of the NaOH?\n"]], ["block_8", ["chlorine. A sample of this compound, when reduced with hydrogen, gives 0.2232 g of tungsten metal and\nhydrogen chloride, which is absorbed in water. Titration of the hydrochloric acid thus produced requires\n46.2 mL of 0.1051 M NaOH to reach the end point. What is the empirical formula of the black tungsten\nchloride?\n"]], ["block_9", [" 4 \u2022 Exercises \n 209 \n"]]], "page_223": [["block_0", [" 210 \n 4 \u2022 Exercises \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_224": [["block_0", ["CHAPTER 5\nThermochemistry\n"]], ["block_1", [{"image_0": "224_0.png", "coords": [72, 104, 622, 379]}]], ["block_2", [" Figure 5.1 \nSliding a match head along a rough surface initiates a combustion reaction that produces energy in the\n"]], ["block_3", ["form of heat and light. (credit: modification of work by Laszlo Ilyes)\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 5.1 Energy Basics \n 5.2 Calorimetry \n 5.3 Enthalpy \n"]], ["block_6", [" INTRODUCTION \n"]], ["block_7", ["energy as well as matter. Societies at all levels of development could not function without the energy released\nby chemical reactions. In 2012, about 85% of US energy consumption came from the combustion of petroleum\nproducts, coal, wood, and garbage. We use this energy to produce electricity (38%); to transport food, raw\nmaterials, manufactured goods, and people (27%); for industrial production (21%); and to heat and power our\nhomes and businesses (10%).While these combustion reactions help us meet our essential energy needs,\nthey are also recognized by the majority of the scientific community as a major contributor to global climate\nchange.\n"]], ["block_8", ["Useful forms of energy are also available from a variety of chemical reactions other than combustion. For\nexample, the energy produced by the batteries in a cell phone, car, or flashlight results from chemical\nreactions. This chapter introduces many of the basic ideas necessary to explore the relationships between\nchemical changes and energy, with a focus on thermal energy.\n"]], ["block_9", ["1 US Energy Information Administration, Primary Energy Consumption by Source and Sector, 2012, http://www.eia.gov/totalenergy/\ndata/monthly/pdf/flow/css_2012_energy.pdf. Data derived from US Energy Information Administration, Monthly Energy Review\n(January 2014).\n"]], ["block_10", ["Chemical reactions, such as those that occur when you light a match, involve changes in\n"]]], "page_225": [["block_0", [" 212 \n 5 \u2022 Thermochemistry \n"]], ["block_1", [" 5.1 Energy Basics \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["Chemical changes and their accompanying changes in energy are important parts of our everyday world\n(Figure 5.2). The macronutrients in food (proteins, fats, and carbohydrates) undergo metabolic reactions that\nprovide the energy to keep our bodies functioning. We burn a variety of fuels (gasoline, natural gas, coal) to\nproduce energy for transportation, heating, and the generation of electricity. Industrial chemical reactions use\nenormous amounts of energy to produce raw materials (such as iron and aluminum). Energy is then used to\nmanufacture those raw materials into useful products, such as cars, skyscrapers, and bridges.\n"]], ["block_4", [{"image_0": "225_0.png", "coords": [72, 260, 540, 386]}]], ["block_5", [" FIGURE 5.2 \nThe energy involved in chemical changes is important to our daily lives: (a) A cheeseburger for lunch\n"]], ["block_6", ["provides the energy you need to get through the rest of the day; (b) the combustion of gasoline provides the energy\nthat moves your car (and you) between home, work, and school; and (c) coke, a processed form of coal, provides the\nenergy needed to convert iron ore into iron, which is essential for making many of the products we use daily. (credit\na: modification of work by \u201cPink Sherbet Photography\u201d/Flickr; credit b: modification of work by Jeffery Turner)\n"]], ["block_7", ["Over 90% of the energy we use comes originally from the sun. Every day, the sun provides the earth with\nalmost 10,000 times the amount of energy necessary to meet all of the world\u2019s energy needs for that day. Our\nchallenge is to find ways to convert and store incoming solar energy so that it can be used in reactions or\nchemical processes that are both convenient and nonpolluting. Plants and many bacteria capture solar energy\nthrough photosynthesis. We release the energy stored in plants when we burn wood or plant products such as\nethanol. We also use this energy to fuel our bodies by eating food that comes directly from plants or from\nanimals that got their energy by eating plants. Burning coal and petroleum also releases stored solar energy:\nThese fuels are fossilized plant and animal matter.\n"]], ["block_8", ["This chapter will introduce the basic ideas of an important area of science concerned with the amount of heat\nabsorbed or released during chemical and physical changes\u2014an area called thermochemistry . The concepts\nintroduced in this chapter are widely used in almost all scientific and technical fields. Food scientists use them\nto determine the energy content of foods. Biologists study the energetics of living organisms, such as the\nmetabolic combustion of sugar into carbon dioxide and water. The oil, gas, and transportation industries,\nrenewable energy providers, and many others endeavor to find better methods to produce energy for our\ncommercial and personal needs. Engineers strive to improve energy efficiency, find better ways to heat and\ncool our homes, refrigerate our food and drinks, and meet the energy and cooling needs of computers and\nelectronics, among other applications. Understanding thermochemical principles is essential for chemists,\nphysicists, biologists, geologists, every type of engineer, and just about anyone who studies or does any kind of\nscience.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["\u2022\nDefine energy, distinguish types of energy, and describe the nature of energy changes that accompany chemical\nand physical changes\n"]], ["block_11", ["\u2022\nDistinguish the related properties of heat, thermal energy, and temperature\n"]], ["block_12", ["\u2022\nDefine and distinguish specific heat and heat capacity, and describe the physical implications of both\n"]], ["block_13", ["\u2022\nPerform calculations involving heat, specific heat, and temperature change\n"]]], "page_226": [["block_0", [" Energy \n"]], ["block_1", [" Energy can be defined as the capacity to supply heat or do work. One type of work (w) is the process of causing\nmatter to move against an opposing force. For example, we do work when we inflate a bicycle tire\u2014we move\nmatter (the air in the pump) against the opposing force of the air already in the tire.\n"]], ["block_2", ["Like matter, energy comes in different types. One scheme classifies energy into two types: potential energy ,\nthe energy an object has because of its relative position, composition, or condition, and kinetic energy , the\nenergy that an object possesses because of its motion. Water at the top of a waterfall or dam has potential\nenergy because of its position; when it flows downward through generators, it has kinetic energy that can be\nused to do work and produce electricity in a hydroelectric plant (Figure 5.3). A battery has potential energy\nbecause the chemicals within it can produce electricity that can do work.\n"]], ["block_3", [" FIGURE 5.3 \n(a) Water at a higher elevation, for example, at the top of Victoria Falls, has a higher potential energy\n"]], ["block_4", ["than water at a lower elevation. As the water falls, some of its potential energy is converted into kinetic energy. (b) If\nthe water flows through generators at the bottom of a dam, such as the Hoover Dam shown here, its kinetic energy\nis converted into electrical energy. (credit a: modification of work by Steve Jurvetson; credit b: modification of work\nby \u201ccurimedia\u201d/Wikimedia commons)\n"]], ["block_5", ["Energy can be converted from one form into another, but all of the energy present before a change occurs\nalways exists in some form after the change is completed. This observation is expressed in the law of\nconservation of energy: during a chemical or physical change, energy can be neither created nor destroyed,\nalthough it can be changed in form. (This is also one version of the first law of thermodynamics, as you will\nlearn later.)\n"]], ["block_6", ["When one substance is converted into another, there is always an associated conversion of one form of energy\ninto another. Heat is usually released or absorbed, but sometimes the conversion involves light, electrical\nenergy, or some other form of energy. For example, chemical energy (a type of potential energy) is stored in the\nmolecules that compose gasoline. When gasoline is combusted within the cylinders of a car\u2019s engine, the\nrapidly expanding gaseous products of this chemical reaction generate mechanical energy (a type of kinetic\nenergy) when they move the cylinders\u2019 pistons.\n"]], ["block_7", ["According to the law of conservation of matter (seen in an earlier chapter), there is no detectable change in the\ntotal amount of matter during a chemical change. When chemical reactions occur, the energy changes are\nrelatively modest and the mass changes are too small to measure, so the laws of conservation of matter and\nenergy hold well. However, in nuclear reactions, the energy changes are much larger (by factors of a million or\nso), the mass changes are measurable, and matter-energy conversions are significant. This will be examined in\nmore detail in a later chapter on nuclear chemistry.\n"]], ["block_8", [" Thermal Energy, Temperature, and Heat \n"]], ["block_9", [" Thermal energy is kinetic energy associated with the random motion of atoms and molecules. Temperature \nis a quantitative measure of \u201chot\u201d or \u201ccold.\u201d When the atoms and molecules in an object are moving or\n"]], ["block_10", [{"image_0": "226_0.png", "coords": [130, 203, 481, 383]}]], ["block_11", [" 5.1 \u2022 Energy Basics \n 213 \n"]]], "page_227": [["block_0", [" 214 \n 5 \u2022 Thermochemistry \n"]], ["block_1", ["vibrating quickly, they have a higher average kinetic energy (KE), and we say that the object is \u201chot.\u201d When the\natoms and molecules are moving slowly, they have lower average KE, and we say that the object is \u201ccold\u201d\n(Figure 5.4). Assuming that no chemical reaction or phase change (such as melting or vaporizing) occurs,\nincreasing the amount of thermal energy in a sample of matter will cause its temperature to increase. And,\nassuming that no chemical reaction or phase change (such as condensation or freezing) occurs, decreasing the\namount of thermal energy in a sample of matter will cause its temperature to decrease.\n"]], ["block_2", ["Click on this interactive simulation (http://openstax.org/l/16PHETtempFX) to view the effects of temperature\non molecular motion.\n"]], ["block_3", ["Most substances expand as their temperature increases and contract as their temperature decreases. This\nproperty can be used to measure temperature changes, as shown in Figure 5.5. The operation of many\nthermometers depends on the expansion and contraction of substances in response to temperature changes.\n"]], ["block_4", [" FIGURE 5.5 \n(a) In an alcohol or mercury thermometer, the liquid (dyed red for visibility) expands when heated and\n"]], ["block_5", ["contracts when cooled, much more so than the glass tube that contains the liquid. (b) In a bimetallic thermometer,\ntwo different metals (such as brass and steel) form a two-layered strip. When heated or cooled, one of the metals\n(brass) expands or contracts more than the other metal (steel), causing the strip to coil or uncoil. Both types of\nthermometers have a calibrated scale that indicates the temperature. (credit a: modification of work by\n\u201cdwstucke\u201d/Flickr)\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [" FIGURE 5.4 \n(a) The molecules in a sample of hot water move more rapidly than (b) those in a sample of cold water.\n"]], ["block_8", [{"image_0": "227_0.png", "coords": [72, 423, 539, 622]}]], ["block_9", ["LINK TO LEARNING\n"]], ["block_10", [{"image_1": "227_1.png", "coords": [176, 139, 435, 292]}]]], "page_228": [["block_0", ["The following demonstration (http://openstax.org/l/16Bimetallic) allows one to view the effects of heating and\ncooling a coiled bimetallic strip.\n"]], ["block_1", [" Heat (q) is the transfer of thermal energy between two bodies at different temperatures. Heat flow (a\nredundant term, but one commonly used) increases the thermal energy of one body and decreases the thermal\nenergy of the other. Suppose we initially have a high temperature (and high thermal energy) substance (H) and\na low temperature (and low thermal energy) substance (L). The atoms and molecules in H have a higher\naverage KE than those in L. If we place substance H in contact with substance L, the thermal energy will flow\nspontaneously from substance H to substance L. The temperature of substance H will decrease, as will the\naverage KE of its molecules; the temperature of substance L will increase, along with the average KE of its\nmolecules. Heat flow will continue until the two substances are at the same temperature (Figure 5.6).\n"]], ["block_2", [" FIGURE 5.6 \n(a) Substances H and L are initially at different temperatures, and their atoms have different average\n"]], ["block_3", ["kinetic energies. (b) When they contact each other, collisions between the molecules result in the transfer of kinetic\n(thermal) energy from the hotter to the cooler matter. (c) The two objects reach \u201cthermal equilibrium\u201d when both\nsubstances are at the same temperature and their molecules have the same average kinetic energy.\n"]], ["block_4", ["Click on the PhET simulation (http://openstax.org/l/16PHETenergy) to explore energy forms and changes. Visit\nthe Energy Systems tab to create combinations of energy sources, transformation methods, and outputs. Click\non Energy Symbols to visualize the transfer of energy.\n"]], ["block_5", ["Matter undergoing chemical reactions and physical changes can release or absorb heat. A change that releases\nheat is called an exothermic process . For example, the combustion reaction that occurs when using an\noxyacetylene torch is an exothermic process\u2014this process also releases energy in the form of light as\nevidenced by the torch\u2019s flame (Figure 5.7). A reaction or change that absorbs heat is an endothermic process .\nA cold pack used to treat muscle strains provides an example of an endothermic process. When the substances\nin the cold pack (water and a salt like ammonium nitrate) are brought together, the resulting process absorbs\nheat, leading to the sensation of cold.\n"]], ["block_6", [{"image_0": "228_0.png", "coords": [77, 230, 534, 344]}]], ["block_7", ["LINK TO LEARNING\n"]], ["block_8", ["LINK TO LEARNING\n"]], ["block_9", [" 5.1 \u2022 Energy Basics \n 215 \n"]]], "page_229": [["block_0", [" 216 \n 5 \u2022 Thermochemistry \n"]], ["block_1", [{"image_0": "229_0.png", "coords": [72, 57, 540, 253]}]], ["block_2", [" FIGURE 5.7 \n(a) An oxyacetylene torch produces heat by the combustion of acetylene in oxygen. The energy\n"]], ["block_3", ["released by this exothermic reaction heats and then melts the metal being cut. The sparks are tiny bits of the molten\nmetal flying away. (b) A cold pack uses an endothermic process to create the sensation of cold. (credit a:\nmodification of work by \u201cSkatebiker\u201d/Wikimedia commons)\n"]], ["block_4", ["Historically, energy was measured in units of calories (cal) . A calorie is the amount of energy required to raise\none gram of water by 1 degree C (1 kelvin). However, this quantity depends on the atmospheric pressure and\nthe starting temperature of the water. The ease of measurement of energy changes in calories has meant that\nthe calorie is still frequently used. The Calorie (with a capital C), or large calorie, commonly used in quantifying\nfood energy content, is a kilocalorie. The SI unit of heat, work, and energy is the joule. A joule (J) is defined as\nthe amount of energy used when a force of 1 newton moves an object 1 meter. It is named in honor of the\nEnglish physicist James Prescott Joule. One joule is equivalent to 1 kg m/s, which is also called 1\nnewton\u2013meter. A kilojoule (kJ) is 1000 joules. To standardize its definition, 1 calorie has been set to equal\n4.184 joules.\n"]], ["block_5", ["We now introduce two concepts useful in describing heat flow and temperature change. The heat capacity (C) \nof a body of matter is the quantity of heat (q) it absorbs or releases when it experiences a temperature change\n(\u0394T) of 1 degree Celsius (or equivalently, 1 kelvin):\n"]], ["block_6", ["Heat capacity is determined by both the type and amount of substance that absorbs or releases heat. It is\ntherefore an extensive property\u2014its value is proportional to the amount of the substance.\n"]], ["block_7", ["For example, consider the heat capacities of two cast iron frying pans. The heat capacity of the large pan is five\ntimes greater than that of the small pan because, although both are made of the same material, the mass of the\nlarge pan is five times greater than the mass of the small pan. More mass means more atoms are present in the\nlarger pan, so it takes more energy to make all of those atoms vibrate faster. The heat capacity of the small cast\niron frying pan is found by observing that it takes 18,150 J of energy to raise the temperature of the pan by\n50.0 \u00b0C:\n"]], ["block_8", ["The larger cast iron frying pan, while made of the same substance, requires 90,700 J of energy to raise its\ntemperature by 50.0 \u00b0C. The larger pan has a (proportionally) larger heat capacity because the larger amount\nof material requires a (proportionally) larger amount of energy to yield the same temperature change:\n"]], ["block_9", ["The specific heat capacity (c) of a substance, commonly called its \u201cspecific heat,\u201d is the quantity of heat\n"]], ["block_10", [" Access for free at openstax.org \n"]]], "page_230": [["block_0", ["required to raise the temperature of 1 gram of a substance by 1 degree Celsius (or 1 kelvin):\n"]], ["block_1", ["Specific heat capacity depends only on the kind of substance absorbing or releasing heat. It is an intensive\nproperty\u2014the type, but not the amount, of the substance is all that matters. For example, the small cast iron\nfrying pan has a mass of 808 g. The specific heat of iron (the material used to make the pan) is therefore:\n"]], ["block_2", ["The large frying pan has a mass of 4040 g. Using the data for this pan, we can also calculate the specific heat of\niron:\n"]], ["block_3", ["Although the large pan is more massive than the small pan, since both are made of the same material, they\nboth yield the same value for specific heat (for the material of construction, iron). Note that specific heat is\nmeasured in units of energy per temperature per mass and is an intensive property, being derived from a ratio\nof two extensive properties (heat and mass). The molar heat capacity, also an intensive property, is the heat\ncapacity per mole of a particular substance and has units of J/mol \u00b0C (Figure 5.8).\n"]], ["block_4", [" FIGURE 5.8 \nBecause of its larger mass, a large frying pan has a larger heat capacity than a small frying pan.\n"]], ["block_5", ["Because they are made of the same material, both frying pans have the same specific heat. (credit: Mark Blaser)\n"]], ["block_6", ["Water has a relatively high specific heat (about 4.2 J/g \u00b0C for the liquid and 2.09 J/g \u00b0C for the solid); most\nmetals have much lower specific heats (usually less than 1 J/g \u00b0C). The specific heat of a substance varies\nsomewhat with temperature. However, this variation is usually small enough that we will treat specific heat as\nconstant over the range of temperatures that will be considered in this chapter. Specific heats of some common\nsubstances are listed in Table 5.1.\n"]], ["block_7", [" TABLE 5.1 \n"]], ["block_8", ["Specific Heats of Common Substances at 25 \u00b0C and 1 bar\n"]], ["block_9", [{"image_0": "230_0.png", "coords": [189, 310, 423, 422]}]], ["block_10", ["water vapor\nH2O(g)\n1.864\n"]], ["block_11", [" Substance \n Symbol (state) \n Specific Heat (J/g \u00b0C) \n"]], ["block_12", ["ethanol\nC2H6O(l)\n2.376\n"]], ["block_13", ["helium\nHe(g)\n5.193\n"]], ["block_14", ["water\nH2O(l)\n4.184\n"]], ["block_15", ["ice\nH2O(s)\n2.093 (at \u221210 \u00b0C)\n"]], ["block_16", [" 5.1 \u2022 Energy Basics \n 217 \n"]]], "page_231": [["block_0", [" 218 \n 5 \u2022 Thermochemistry \n"]], ["block_1", ["If we know the mass of a substance and its specific heat, we can determine the amount of heat, q, entering or\nleaving the substance by measuring the temperature change before and after the heat is gained or lost:\n"]], ["block_2", ["In this equation, c is the specific heat of the substance, m is its mass, and \u0394T (which is read \u201cdelta T\u201d) is the\ntemperature change, Tfinal \u2212 Tinitial. If a substance gains thermal energy, its temperature increases, its final\ntemperature is higher than its initial temperature, Tfinal \u2212 Tinitial has a positive value, and the value of q is\npositive. If a substance loses thermal energy, its temperature decreases, the final temperature is lower than the\ninitial temperature, Tfinal \u2212 Tinitial has a negative value, and the value of q is negative.\n"]], ["block_3", [" Measuring Heat \n"]], ["block_4", ["A flask containing 8.0\n10g of water is heated, and the temperature of the water increases from 21 \u00b0C to 85\n"]], ["block_5", ["\u00b0C. How much heat did the water absorb?\n"]], ["block_6", [" Solution \n"]], ["block_7", ["To answer this question, consider these factors:\n"]], ["block_8", ["The specific heat of water is 4.184 J/g \u00b0C, so to heat 1 g of water by 1 \u00b0C requires 4.184 J. We note that since\n4.184 J is required to heat 1 g of water by 1 \u00b0C, we will need 800 times as much to heat 8.0 \u00d7 10g of water by 1\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["\u2022\nthe specific heat of the substance being heated (in this case, water)\n"]], ["block_11", ["\u2022\nthe amount of substance being heated (in this case, 8.0 \u00d7 10g)\n"]], ["block_12", ["\u2022\nthe magnitude of the temperature change (in this case, from 21 \u00b0C to 85 \u00b0C).\n"]], ["block_13", ["EXAMPLE 5.1\n"]], ["block_14", [" TABLE 5.1 \n"]], ["block_15", ["carbon dioxide\nCO2(g)\n0.853\n"]], ["block_16", [" Substance \n Symbol (state) \n Specific Heat (J/g \u00b0C) \n"]], ["block_17", ["aluminum\nAl(s)\n0.897\n"]], ["block_18", ["nitrogen\nN2(g)\n1.040\n"]], ["block_19", ["oxygen\nO2(g)\n0.918\n"]], ["block_20", ["copper\nCu(s)\n0.385\n"]], ["block_21", ["silicon\nSi(s)\n0.712\n"]], ["block_22", ["argon\nAr(g)\n0.522\n"]], ["block_23", ["gold\nAu(s)\n0.129\n"]], ["block_24", ["lead\nPb(s)\n0.130\n"]], ["block_25", ["iron\nFe(s)\n0.449\n"]], ["block_26", ["air\n1.007\n"]]], "page_232": [["block_0", ["\u00b0C. Finally, we observe that since 4.184 J are required to heat 1 g of water by 1 \u00b0C, we will need 64 times as\nmuch to heat it by 64 \u00b0C (that is, from 21 \u00b0C to 85 \u00b0C).\n"]], ["block_1", [" Answer: \nc = 0.451 J/g \u00b0C; the metal is likely to be iron\n"]], ["block_2", ["This can be summarized using the equation:\n"]], ["block_3", ["Because the temperature increased, the water absorbed heat and q is positive.\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["How much heat, in joules, must be added to a 502 g iron skillet to increase its temperature from 25 \u00b0C to 250\n\u00b0C? The specific heat of iron is 0.449 J/g \u00b0C.\n"]], ["block_6", [" Answer: \n5.07\n10J\n"]], ["block_7", ["Note that the relationship between heat, specific heat, mass, and temperature change can be used to\ndetermine any of these quantities (not just heat) if the other three are known or can be deduced.\n"]], ["block_8", [" Determining Other Quantities \n"]], ["block_9", ["A piece of unknown metal weighs 348 g. When the metal piece absorbs 6.64 kJ of heat, its temperature\nincreases from 22.4 \u00b0C to 43.6 \u00b0C. Determine the specific heat of this metal (which might provide a clue to its\nidentity).\n"]], ["block_10", [" Solution \n"]], ["block_11", ["Since mass, heat, and temperature change are known for this metal, we can determine its specific heat using\nthe relationship:\n"]], ["block_12", ["Substituting the known values:\n"]], ["block_13", ["Solving:\n"]], ["block_14", ["Comparing this value with the values in Table 5.1, this value matches the specific heat of aluminum, which\nsuggests that the unknown metal may be aluminum.\n"]], ["block_15", [" Check Your Learning \n"]], ["block_16", ["A piece of unknown metal weighs 217 g. When the metal piece absorbs 1.43 kJ of heat, its temperature\nincreases from 24.5 \u00b0C to 39.1 \u00b0C. Determine the specific heat of this metal, and predict its identity.\n"]], ["block_17", ["EXAMPLE 5.2\n"]], ["block_18", [" 5.1 \u2022 Energy Basics \n 219 \n"]]], "page_233": [["block_0", [" 220 \n 5 \u2022 Thermochemistry \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", ["Chemistry in Everyday Life\n"]], ["block_3", [" Solar Thermal Energy Power Plants \nThe sunlight that reaches the earth contains thousands of times more energy than we presently capture.\nSolar thermal systems provide one possible solution to the problem of converting energy from the sun into\nenergy we can use. Large-scale solar thermal plants have different design specifics, but all concentrate\nsunlight to heat some substance; the heat \u201cstored\u201d in that substance is then converted into electricity.\n"]], ["block_4", ["The Solana Generating Station in Arizona\u2019s Sonora Desert produces 280 megawatts of electrical power. It\nuses parabolic mirrors that focus sunlight on pipes filled with a heat transfer fluid (HTF) (Figure 5.9). The\nHTF then does two things: It turns water into steam, which spins turbines, which in turn produces\nelectricity, and it melts and heats a mixture of salts, which functions as a thermal energy storage system.\nAfter the sun goes down, the molten salt mixture can then release enough of its stored heat to produce\nsteam to run the turbines for 6 hours. Molten salts are used because they possess a number of beneficial\nproperties, including high heat capacities and thermal conductivities.\n"]], ["block_5", [" FIGURE 5.9 \nThis solar thermal plant uses parabolic trough mirrors to concentrate sunlight. (credit a:\n"]], ["block_6", ["modification of work by Bureau of Land Management)\n"]], ["block_7", ["The 377-megawatt Ivanpah Solar Generating System, located in the Mojave Desert in California, is the\nlargest solar thermal power plant in the world (Figure 5.10). Its 170,000 mirrors focus huge amounts of\nsunlight on three water-filled towers, producing steam at over 538 \u00b0C that drives electricity-producing\nturbines. It produces enough energy to power 140,000 homes. Water is used as the working fluid because\nof its large heat capacity and heat of vaporization.\n"]], ["block_8", [{"image_0": "233_0.png", "coords": [90, 250, 522, 434]}]]], "page_234": [["block_0", [" 5.2 Calorimetry \n"]], ["block_1", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_2", ["One technique we can use to measure the amount of heat involved in a chemical or physical process is known\nas calorimetry . Calorimetry is used to measure amounts of heat transferred to or from a substance. To do so,\nthe heat is exchanged with a calibrated object (calorimeter). The temperature change measured by the\ncalorimeter is used to derive the amount of heat transferred by the process under study. The measurement of\nheat transfer using this approach requires the definition of a system (the substance or substances undergoing\nthe chemical or physical change) and its surroundings (all other matter, including components of the\nmeasurement apparatus, that serve to either provide heat to the system or absorb heat from the system).\n"]], ["block_3", ["A calorimeter is a device used to measure the amount of heat involved in a chemical or physical process. For\nexample, when an exothermic reaction occurs in solution in a calorimeter, the heat produced by the reaction is\nabsorbed by the solution, which increases its temperature. When an endothermic reaction occurs, the heat\nrequired is absorbed from the thermal energy of the solution, which decreases its temperature (Figure 5.11).\nThe temperature change, along with the specific heat and mass of the solution, can then be used to calculate\nthe amount of heat involved in either case.\n"]], ["block_4", ["\u2022\nExplain the technique of calorimetry\n"]], ["block_5", ["\u2022\nCalculate and interpret heat and related properties using typical calorimetry data\n"]], ["block_6", [" FIGURE 5.10 \n(a) The Ivanpah solar thermal plant uses 170,000 mirrors to concentrate sunlight on water-filled\n"]], ["block_7", ["towers. (b) It covers 4000 acres of public land near the Mojave Desert and the California-Nevada border. (credit\na: modification of work by Craig Dietrich; credit b: modification of work by \u201cUSFWS Pacific Southwest\nRegion\u201d/Flickr)\n"]], ["block_8", [{"image_0": "234_0.png", "coords": [90, 57, 522, 230]}]], ["block_9", [" 5.2 \u2022 Calorimetry \n 221 \n"]]], "page_235": [["block_0", [" 222 \n 5 \u2022 Thermochemistry \n"]], ["block_1", [{"image_0": "235_0.png", "coords": [72, 57, 540, 291]}]], ["block_2", [" FIGURE 5.11 \nIn a calorimetric determination, either (a) an exothermic process occurs and heat, q, is negative,\n"]], ["block_3", ["indicating that thermal energy is transferred from the system to its surroundings, or (b) an endothermic process\noccurs and heat, q, is positive, indicating that thermal energy is transferred from the surroundings to the system.\n"]], ["block_4", ["Calorimetry measurements are important in understanding the heat transferred in reactions involving\neverything from microscopic proteins to massive machines. During her time at the National Bureau of\nStandards, research chemist Reatha Clark King performed calorimetric experiments to understand the precise\nheats of various flourine compounds. Her work was important to NASA in their quest for better rocket fuels.\n"]], ["block_5", ["Scientists use well-insulated calorimeters that all but prevent the transfer of heat between the calorimeter and\nits environment, which effectively limits the \u201csurroundings\u201d to the nonsystem components with the\ncalorimeter (and the calorimeter itself). This enables the accurate determination of the heat involved in\nchemical processes, the energy content of foods, and so on. General chemistry students often use simple\ncalorimeters constructed from polystyrene cups (Figure 5.12). These easy-to-use \u201ccoffee cup\u201d calorimeters\nallow more heat exchange with the outside environment, and therefore produce less accurate energy values.\n"]], ["block_6", [" Access for free at openstax.org \n"]]], "page_236": [["block_0", [" FIGURE 5.12 \nA simple calorimeter can be constructed from two polystyrene cups. A thermometer and stirrer\n"]], ["block_1", ["extend through the cover into the reaction mixture.\n"]], ["block_2", ["Commercial solution calorimeters are also available. Relatively inexpensive calorimeters often consist of two\nthin-walled cups that are nested in a way that minimizes thermal contact during use, along with an insulated\ncover, handheld stirrer, and simple thermometer. More expensive calorimeters used for industry and research\ntypically have a well-insulated, fully enclosed reaction vessel, motorized stirring mechanism, and a more\naccurate temperature sensor (Figure 5.13).\n"]], ["block_3", [{"image_0": "236_0.png", "coords": [189, 57, 423, 432]}]], ["block_4", [" 5.2 \u2022 Calorimetry \n 223 \n"]]], "page_237": [["block_0", [" 224 \n 5 \u2022 Thermochemistry \n"]], ["block_1", [{"image_0": "237_0.png", "coords": [72, 57, 540, 360]}]], ["block_2", [" FIGURE 5.13 \nCommercial solution calorimeters range from (a) simple, inexpensive models for student use to (b)\n"]], ["block_3", ["expensive, more accurate models for industry and research.\n"]], ["block_4", ["Before discussing the calorimetry of chemical reactions, consider a simpler example that illustrates the core\nidea behind calorimetry. Suppose we initially have a high-temperature substance, such as a hot piece of metal\n(M), and a low-temperature substance, such as cool water (W). If we place the metal in the water, heat will flow\nfrom M to W. The temperature of M will decrease, and the temperature of W will increase, until the two\nsubstances have the same temperature\u2014that is, when they reach thermal equilibrium (Figure 5.14). If this\noccurs in a calorimeter, ideally all of this heat transfer occurs between the two substances, with no heat gained\nor lost by either its external environment. Under these ideal circumstances, the net heat change is zero:\n"]], ["block_5", ["This relationship can be rearranged to show that the heat gained by substance M is equal to the heat lost by\nsubstance W:\n"]], ["block_6", ["The magnitude of the heat (change) is therefore the same for both substances, and the negative sign merely\nshows that qsubstance M and qsubstance W are opposite in direction of heat flow (gain or loss) but does not indicate\nthe arithmetic sign of either q value (that is determined by whether the matter in question gains or loses heat,\nper definition). In the specific situation described, qsubstance M is a negative value and qsubstance W is positive,\nsince heat is transferred from M to W.\n"]], ["block_7", [" Access for free at openstax.org \n"]]], "page_238": [["block_0", ["The temperature of the water increases from 24.0 \u00b0C to 42.7 \u00b0C, so the water absorbs heat. That heat came\nfrom the piece of rebar, which initially was at a higher temperature. Assuming that all heat transfer was\nbetween the rebar and the water, with no heat \u201clost\u201d to the outside environment, then heat given off by rebar =\n\u2212heat taken in by water, or:\n"]], ["block_1", [" FIGURE 5.14 \nIn a simple calorimetry process, (a) heat, q, is transferred from the hot metal, M, to the cool water,\n"]], ["block_2", ["W, until (b) both are at the same temperature.\n"]], ["block_3", [" Heat Transfer between Substances at Different Temperatures \n"]], ["block_4", ["A 360.0-g piece of rebar (a steel rod used for reinforcing concrete) is dropped into 425 mL of water at 24.0 \u00b0C.\nThe final temperature of the water was measured as 42.7 \u00b0C. Calculate the initial temperature of the piece of\nrebar. Assume the specific heat of steel is approximately the same as that for iron (Table 5.1), and that all heat\ntransfer occurs between the rebar and the water (there is no heat exchange with the surroundings).\n"]], ["block_5", [" Solution \n"]], ["block_6", ["Since we know how heat is related to other measurable quantities, we have:\n"]], ["block_7", ["Letting f = final and i = initial, in expanded form, this becomes:\n"]], ["block_8", ["The density of water is 1.0 g/mL, so 425 mL of water = 425 g. Noting that the final temperature of both the\nrebar and water is 42.7 \u00b0C, substituting known values yields:\n"]], ["block_9", ["Solving this gives Ti,rebar= 248 \u00b0C, so the initial temperature of the rebar was 248 \u00b0C.\n"]], ["block_10", [" Check Your Learning \n"]], ["block_11", ["A 248-g piece of copper is dropped into 390 mL of water at 22.6 \u00b0C. The final temperature of the water was\n"]], ["block_12", ["EXAMPLE 5.3\n"]], ["block_13", [{"image_0": "238_0.png", "coords": [189, 57, 423, 290]}]], ["block_14", [" 5.2 \u2022 Calorimetry \n 225 \n"]]], "page_239": [["block_0", [" 226 \n 5 \u2022 Thermochemistry \n"]], ["block_1", [" Answer: \ncmetal= 0.13 J/g \u00b0C\n"]], ["block_2", ["measured as 39.9 \u00b0C. Calculate the initial temperature of the piece of copper. Assume that all heat transfer\noccurs between the copper and the water.\n"]], ["block_3", [" Answer: \nThe initial temperature of the copper was 335.6 \u00b0C.\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["A 248-g piece of copper initially at 314 \u00b0C is dropped into 390 mL of water initially at 22.6 \u00b0C. Assuming that all\nheat transfer occurs between the copper and the water, calculate the final temperature.\n"]], ["block_6", [" Answer: \nThe final temperature (reached by both copper and water) is 38.7 \u00b0C.\n"]], ["block_7", ["This method can also be used to determine other quantities, such as the specific heat of an unknown metal.\n"]], ["block_8", [" Identifying a Metal by Measuring Specific Heat \n"]], ["block_9", ["A 59.7 g piece of metal that had been submerged in boiling water was quickly transferred into 60.0 mL of water\ninitially at 22.0 \u00b0C. The final temperature is 28.5 \u00b0C. Use these data to determine the specific heat of the metal.\nUse this result to identify the metal.\n"]], ["block_10", [" Solution \n"]], ["block_11", ["Assuming perfect heat transfer, heat given off by metal = \u2212heat taken in by water, or:\n"]], ["block_12", ["In expanded form, this is:\n"]], ["block_13", ["Noting that since the metal was submerged in boiling water, its initial temperature was 100.0 \u00b0C; and that for\nwater, 60.0 mL = 60.0 g; we have:\n"]], ["block_14", ["Solving this:\n"]], ["block_15", ["Comparing this with values in Table 5.1, our experimental specific heat is closest to the value for copper (0.39\nJ/g \u00b0C), so we identify the metal as copper.\n"]], ["block_16", [" Check Your Learning \n"]], ["block_17", ["A 92.9-g piece of a silver/gray metal is heated to 178.0 \u00b0C, and then quickly transferred into 75.0 mL of water\ninitially at 24.0 \u00b0C. After 5 minutes, both the metal and the water have reached the same temperature: 29.7 \u00b0C.\nDetermine the specific heat and the identity of the metal. (Note: You should find that the specific heat is close\nto that of two different metals. Explain how you can confidently determine the identity of the metal).\n"]], ["block_18", ["This specific heat is close to that of either gold or lead. It would be difficult to determine which metal this was\nbased solely on the numerical values. However, the observation that the metal is silver/gray in addition to the\nvalue for the specific heat indicates that the metal is lead.\n"]], ["block_19", ["When we use calorimetry to determine the heat involved in a chemical reaction, the same principles we have\n"]], ["block_20", [" Access for free at openstax.org \n"]], ["block_21", ["EXAMPLE 5.4\n"]]], "page_240": [["block_0", ["been discussing apply. The amount of heat absorbed by the calorimeter is often small enough that we can\nneglect it (though not for highly accurate measurements, as discussed later), and the calorimeter minimizes\nenergy exchange with the outside environment. Because energy is neither created nor destroyed during a\nchemical reaction, the heat produced or consumed in the reaction (the \u201csystem\u201d), qreaction, plus the heat\nabsorbed or lost by the solution (the \u201csurroundings\u201d), qsolution, must add up to zero:\n"]], ["block_1", ["This means that the amount of heat produced or consumed in the reaction equals the amount of heat absorbed\nor lost by the solution:\n"]], ["block_2", ["This concept lies at the heart of all calorimetry problems and calculations.\n"]], ["block_3", [" Heat Produced by an Exothermic Reaction \n"]], ["block_4", ["When 50.0 mL of 1.00 M HCl(aq) and 50.0 mL of 1.00 M NaOH(aq), both at 22.0 \u00b0C, are added to a coffee cup\ncalorimeter, the temperature of the mixture reaches a maximum of 28.9 \u00b0C. What is the approximate amount\nof heat produced by this reaction?\n"]], ["block_5", [" Solution \n"]], ["block_6", ["To visualize what is going on, imagine that you could combine the two solutions so quickly that no reaction\ntook place while they mixed; then after mixing, the reaction took place. At the instant of mixing, you have\n100.0 mL of a mixture of HCl and NaOH at 22.0 \u00b0C. The HCl and NaOH then react until the solution\ntemperature reaches 28.9 \u00b0C.\n"]], ["block_7", ["The heat given off by the reaction is equal to that taken in by the solution. Therefore:\n"]], ["block_8", ["(It is important to remember that this relationship only holds if the calorimeter does not absorb any heat from\nthe reaction, and there is no heat exchange between the calorimeter and the outside environment.)\n"]], ["block_9", ["Next, we know that the heat absorbed by the solution depends on its specific heat, mass, and temperature\nchange:\n"]], ["block_10", ["To proceed with this calculation, we need to make a few more reasonable assumptions or approximations.\nSince the solution is aqueous, we can proceed as if it were water in terms of its specific heat and mass values.\nThe density of water is approximately 1.0 g/mL, so 100.0 mL has a mass of about 1.0\n10g (two significant\n"]], ["block_11", ["figures). The specific heat of water is approximately 4.184 J/g \u00b0C, so we use that for the specific heat of the\nsolution. Substituting these values gives:\n"]], ["block_12", ["Finally, since we are trying to find the heat of the reaction, we have:\n"]], ["block_13", ["The negative sign indicates that the reaction is exothermic. It produces 2.9 kJ of heat.\n"]], ["block_14", [" Check Your Learning \n"]], ["block_15", ["When 100 mL of 0.200 M NaCl(aq) and 100 mL of 0.200 M AgNO3(aq), both at 21.9 \u00b0C, are mixed in a coffee cup\ncalorimeter, the temperature increases to 23.5 \u00b0C as solid AgCl forms. How much heat is produced by this\nprecipitation reaction? What assumptions did you make to determine your value?\n"]], ["block_16", ["EXAMPLE 5.5\n"]], ["block_17", [" 5.2 \u2022 Calorimetry \n 227 \n"]]], "page_241": [["block_0", [" 228 \n 5 \u2022 Thermochemistry \n"]], ["block_1", [" Answer: \n1.34\n1.3 kJ; assume no heat is absorbed by the calorimeter, no heat is exchanged between the calorimeter\n"]], ["block_2", ["and its surroundings, and that the specific heat and mass of the solution are the same as those for water\n"]], ["block_3", ["This link (http://openstax.org/l/16Handwarmer) shows the precipitation reaction that occurs when the disk in\na chemical hand warmer is flexed.\n"]], ["block_4", [" Heat Flow in an Instant Ice Pack \n"]], ["block_5", ["When solid ammonium nitrate dissolves in water, the solution becomes cold. This is the basis for an \u201cinstant\nice pack\u201d (Figure 5.16). When 3.21 g of solid NH4NO3 dissolves in 50.0 g of water at 24.9 \u00b0C in a calorimeter, the\ntemperature decreases to 20.3 \u00b0C.\n"]], ["block_6", ["Calculate the value of q for this reaction and explain the meaning of its arithmetic sign. State any assumptions\nthat you made.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", ["Chemistry in Everyday Life\n"]], ["block_9", [" Thermochemistry of Hand Warmers \nWhen working or playing outdoors on a cold day, you might use a hand warmer to warm your hands (Figure\n5.15). A common reusable hand warmer contains a supersaturated solution of NaC2H3O2 (sodium acetate)\nand a metal disc. Bending the disk creates nucleation sites around which the metastable NaC2H3O2 quickly\ncrystallizes (a later chapter on solutions will investigate saturation and supersaturation in more detail).\n"]], ["block_10", ["The process\nis exothermic, and the heat produced by this process is\n"]], ["block_11", ["absorbed by your hands, thereby warming them (at least for a while). If the hand warmer is reheated, the\nNaC2H3O2 redissolves and can be reused.\n"]], ["block_12", [" FIGURE 5.15 \nChemical hand warmers produce heat that warms your hand on a cold day. In this one, you can\n"]], ["block_13", ["see the metal disc that initiates the exothermic precipitation reaction. (credit: modification of work by Science\nBuddies TV/YouTube)\n"]], ["block_14", ["Another common hand warmer produces heat when it is ripped open, exposing iron and water in the hand\nwarmer to oxygen in the air. One simplified version of this exothermic reaction is\n"]], ["block_15", ["rapidly; cellulose, vermiculite, and activated carbon help distribute the heat evenly. Other types of hand\nwarmers use lighter fluid (a platinum catalyst helps lighter fluid oxidize exothermically), charcoal (charcoal\noxidizes in a special case), or electrical units that produce heat by passing an electrical current from a\nbattery through resistive wires.\n"]], ["block_16", [{"image_0": "241_0.png", "coords": [90, 260, 522, 350]}]], ["block_17", ["LINK TO LEARNING\n"]], ["block_18", ["EXAMPLE 5.6\n"]], ["block_19", ["Salt in the hand warmer catalyzes the reaction, so it produces heat more\n"]]], "page_242": [["block_0", [" FIGURE 5.16 \nAn instant cold pack consists of a bag containing solid ammonium nitrate and a second bag of water.\n"]], ["block_1", ["When the bag of water is broken, the pack becomes cold because the dissolution of ammonium nitrate is an\nendothermic process that removes thermal energy from the water. The cold pack then removes thermal energy from\nyour body.\n"]], ["block_2", [" Solution \n"]], ["block_3", ["We assume that the calorimeter prevents heat transfer between the solution and its external environment\n(including the calorimeter itself), in which case:\n"]], ["block_4", ["with \u201crxn\u201d and \u201csoln\u201d used as shorthand for \u201creaction\u201d and \u201csolution,\u201d respectively.\n"]], ["block_5", ["Assuming also that the specific heat of the solution is the same as that for water, we have:\n"]], ["block_6", ["The positive sign for q indicates that the dissolution is an endothermic process.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["When a 3.00-g sample of KCl was added to 3.00\n10g of water in a coffee cup calorimeter, the temperature\n"]], ["block_9", ["decreased by 1.05 \u00b0C. How much heat is involved in the dissolution of the KCl? What assumptions did you\nmake?\n"]], ["block_10", [" Answer: \n1.33 kJ; assume that the calorimeter prevents heat transfer between the solution and its external environment\n(including the calorimeter itself) and that the specific heat of the solution is the same as that for water\n"]], ["block_11", [{"image_0": "242_0.png", "coords": [130, 57, 481, 344]}]], ["block_12", [" 5.2 \u2022 Calorimetry \n 229 \n"]]], "page_243": [["block_0", [" 230 \n 5 \u2022 Thermochemistry \n"]], ["block_1", ["If the amount of heat absorbed by a calorimeter is too large to neglect or if we require more accurate results,\nthen we must take into account the heat absorbed both by the solution and by the calorimeter.\n"]], ["block_2", ["The calorimeters described are designed to operate at constant (atmospheric) pressure and are convenient to\nmeasure heat flow accompanying processes that occur in solution. A different type of calorimeter that operates\nat constant volume, colloquially known as a bomb calorimeter , is used to measure the energy produced by\nreactions that yield large amounts of heat and gaseous products, such as combustion reactions. (The term\n\u201cbomb\u201d comes from the observation that these reactions can be vigorous enough to resemble explosions that\nwould damage other calorimeters.) This type of calorimeter consists of a robust steel container (the \u201cbomb\u201d)\nthat contains the reactants and is itself submerged in water (Figure 5.17). The sample is placed in the bomb,\nwhich is then filled with oxygen at high pressure. A small electrical spark is used to ignite the sample. The\nenergy produced by the reaction is absorbed by the steel bomb and the surrounding water. The temperature\nincrease is measured and, along with the known heat capacity of the calorimeter, is used to calculate the\nenergy produced by the reaction. Bomb calorimeters require calibration to determine the heat capacity of the\ncalorimeter and ensure accurate results. The calibration is accomplished using a reaction with a known q,\nsuch as a measured quantity of benzoic acid ignited by a spark from a nickel fuse wire that is weighed before\nand after the reaction. The temperature change produced by the known reaction is used to determine the heat\ncapacity of the calorimeter. The calibration is generally performed each time before the calorimeter is used to\ngather research data.\n"]], ["block_3", [{"image_0": "243_0.png", "coords": [72, 296, 540, 532]}]], ["block_4", [" FIGURE 5.17 \n(a) A bomb calorimeter is used to measure heat produced by reactions involving gaseous reactants\n"]], ["block_5", ["or products, such as combustion. (b) The reactants are contained in the gas-tight \u201cbomb,\u201d which is submerged in\nwater and surrounded by insulating materials. (credit a: modification of work by \u201cHarbor1\u201d/Wikimedia commons)\n"]], ["block_6", ["Click on this link (http://openstax.org/l/16BombCal) to view how a bomb calorimeter is prepared for action.\n"]], ["block_7", ["This site (http://openstax.org/l/16Calorcalcs) shows calorimetric calculations using sample data.\n"]], ["block_8", [" Bomb Calorimetry \n"]], ["block_9", ["When 3.12 g of glucose, C6H12O6, is burned in a bomb calorimeter, the temperature of the calorimeter\nincreases from 23.8 \u00b0C to 35.6 \u00b0C. The calorimeter contains 775 g of water, and the bomb itself has a heat\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["LINK TO LEARNING\n"]], ["block_12", ["EXAMPLE 5.7\n"]]], "page_244": [["block_0", ["capacity of 893 J/\u00b0C. How much heat was produced by the combustion of the glucose sample?\n"]], ["block_1", [" Solution \n"]], ["block_2", ["The combustion produces heat that is primarily absorbed by the water and the bomb. (The amounts of heat\nabsorbed by the reaction products and the unreacted excess oxygen are relatively small and dealing with them\nis beyond the scope of this text. We will neglect them in our calculations.)\n"]], ["block_3", ["The heat produced by the reaction is absorbed by the water and the bomb:\n"]], ["block_4", ["This reaction released 48.7 kJ of heat when 3.12 g of glucose was burned.\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["When 0.963 g of benzene, C6H6, is burned in a bomb calorimeter, the temperature of the calorimeter increases\nby 8.39 \u00b0C. The bomb has a heat capacity of 784 J/\u00b0C and is submerged in 925 mL of water. How much heat was\nproduced by the combustion of the benzene sample?\n"]], ["block_7", [" Answer: \nqrx = \u201339.0 kJ (the reaction produced 39.0 kJ of heat)\n"]], ["block_8", ["Since the first one was constructed in 1899, 35 calorimeters have been built to measure the heat produced by a\nliving person.These whole-body calorimeters of various designs are large enough to hold an individual\nhuman being. More recently, whole-room calorimeters allow for relatively normal activities to be performed,\nand these calorimeters generate data that more closely reflect the real world. These calorimeters are used to\nmeasure the metabolism of individuals under different environmental conditions, different dietary regimes,\nand with different health conditions, such as diabetes.\n"]], ["block_9", ["For example Carla Prado's team at University of Alberta undertook whole-body calorimetry to understand the\nenergy expenditures of women who had recently given birth. Studies like this help develop better\nrecommendations and regimens for nutrition, exercise, and general wellbeing during this period of significant\nphysiological change. In humans, metabolism is typically measured in Calories per day. A nutritional calorie \n (Calorie) is the energy unit used to quantify the amount of energy derived from the metabolism of foods; one\nCalorie is equal to 1000 calories (1 kcal), the amount of energy needed to heat 1 kg of water by 1 \u00b0C.\n"]], ["block_10", ["2 Francis D. Reardon et al. \u201cThe Snellen human calorimeter revisited, re-engineered and upgraded: Design and performance\ncharacteristics.\u201d Medical and Biological Engineering and Computing 8 (2006)721\u201328, http://link.springer.com/article/10.1007/\ns11517-006-0086-5.\n"]], ["block_11", ["Chemistry in Everyday Life\n"]], ["block_12", [" Measuring Nutritional Calories \nIn your day-to-day life, you may be more familiar with energy being given in Calories, or nutritional\ncalories, which are used to quantify the amount of energy in foods. One calorie (cal) = exactly 4.184 joules,\nand one Calorie (note the capitalization) = 1000 cal, or 1 kcal. (This is approximately the amount of energy\nneeded to heat 1 kg of water by 1 \u00b0C.)\n"]], ["block_13", ["The macronutrients in food are proteins, carbohydrates, and fats or oils. Proteins provide about 4 Calories\nper gram, carbohydrates also provide about 4 Calories per gram, and fats and oils provide about 9 Calories/\ng. Nutritional labels on food packages show the caloric content of one serving of the food, as well as the\nbreakdown into Calories from each of the three macronutrients (Figure 5.18).\n"]], ["block_14", [" 5.2 \u2022 Calorimetry \n 231 \n"]]], "page_245": [["block_0", [" 232 \n 5 \u2022 Thermochemistry \n"]], ["block_1", ["Click on this link (http://openstax.org/l/16USDA) to access the US Department of Agriculture (USDA) National\nNutrient Database, containing nutritional information on over 8000 foods.\n"]], ["block_2", [" Access for free at openstax.org \n"]], ["block_3", [" FIGURE 5.18 \n(a) Macaroni and cheese contain energy in the form of the macronutrients in the food. (b) The\n"]], ["block_4", ["food\u2019s nutritional information is shown on the package label. In the US, the energy content is given in Calories\n(per serving); the rest of the world usually uses kilojoules. (credit a: modification of work by \u201cRex Roof\u201d/Flickr)\n"]], ["block_5", ["For the example shown in (b), the total energy per 228-g portion is calculated by:\n"]], ["block_6", ["So, you can use food labels to count your Calories. But where do the values come from? And how accurate\nare they? The caloric content of foods can be determined by using bomb calorimetry; that is, by burning\nthe food and measuring the energy it contains. A sample of food is weighed, mixed in a blender, freeze-\ndried, ground into powder, and formed into a pellet. The pellet is burned inside a bomb calorimeter, and\nthe measured temperature change is converted into energy per gram of food.\n"]], ["block_7", ["Today, the caloric content on food labels is derived using a method called the Atwater system that uses the\naverage caloric content of the different chemical constituents of food, protein, carbohydrate, and fats. The\naverage amounts are those given in the equation and are derived from the various results given by bomb\ncalorimetry of whole foods. The carbohydrate amount is discounted a certain amount for the fiber content,\nwhich is indigestible carbohydrate. To determine the energy content of a food, the quantities of\ncarbohydrate, protein, and fat are each multiplied by the average Calories per gram for each and the\nproducts summed to obtain the total energy.\n"]], ["block_8", [{"image_0": "245_0.png", "coords": [90, 57, 522, 301]}]], ["block_9", ["LINK TO LEARNING\n"]]], "page_246": [["block_0", ["system, qin, or work is done on the system, won, its internal energy increases, \u0394U > 0. If heat flows out of the system,\nqout, or work is done by the system, wby, its internal energy decreases, \u0394U < 0.\n"]], ["block_1", [" 5.3 Enthalpy \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["Thermochemistry is a branch of chemical thermodynamics , the science that deals with the relationships\nbetween heat, work, and other forms of energy in the context of chemical and physical processes. As we\nconcentrate on thermochemistry in this chapter, we need to consider some widely used concepts of\nthermodynamics.\n"]], ["block_4", ["Substances act as reservoirs of energy, meaning that energy can be added to them or removed from them.\nEnergy is stored in a substance when the kinetic energy of its atoms or molecules is raised. The greater kinetic\nenergy may be in the form of increased translations (travel or straight-line motions), vibrations, or rotations of\nthe atoms or molecules. When thermal energy is lost, the intensities of these motions decrease and the kinetic\nenergy falls. The total of all possible kinds of energy present in a substance is called the internal energy (U) ,\nsometimes symbolized as E.\n"]], ["block_5", ["As a system undergoes a change, its internal energy can change, and energy can be transferred from the\nsystem to the surroundings, or from the surroundings to the system. Energy is transferred into a system when\nit absorbs heat (q) from the surroundings or when the surroundings do work (w) on the system. For example,\nenergy is transferred into room-temperature metal wire if it is immersed in hot water (the wire absorbs heat\nfrom the water), or if you rapidly bend the wire back and forth (the wire becomes warmer because of the work\ndone on it). Both processes increase the internal energy of the wire, which is reflected in an increase in the\nwire\u2019s temperature. Conversely, energy is transferred out of a system when heat is lost from the system, or\nwhen the system does work on the surroundings.\n"]], ["block_6", ["The relationship between internal energy, heat, and work can be represented by the equation:\n"]], ["block_7", ["as shown in Figure 5.19. This is one version of the first law of thermodynamics , and it shows that the internal\nenergy of a system changes through heat flow into or out of the system (positive q is heat flow in; negative q is\nheat flow out) or work done on or by the system. The work, w, is positive if it is done on the system and negative\nif it is done by the system.\n"]], ["block_8", [" FIGURE 5.19 \nThe internal energy, U, of a system can be changed by heat flow and work. If heat flows into the\n"]], ["block_9", ["A type of work called expansion work (or pressure-volume work) occurs when a system pushes back the\n"]], ["block_10", ["\u2022\nState the first law of thermodynamics\n"]], ["block_11", ["\u2022\nDefine enthalpy and explain its classification as a state function\n"]], ["block_12", ["\u2022\nWrite and balance thermochemical equations\n"]], ["block_13", ["\u2022\nCalculate enthalpy changes for various chemical reactions\n"]], ["block_14", ["\u2022\nExplain Hess\u2019s law and use it to compute reaction enthalpies\n"]], ["block_15", [{"image_0": "246_0.png", "coords": [189, 515, 423, 673]}]], ["block_16", [" 5.3 \u2022 Enthalpy \n 233 \n"]]], "page_247": [["block_0", [" 234 \n 5 \u2022 Thermochemistry \n"]], ["block_1", ["surroundings against a restraining pressure, or when the surroundings compress the system. An example of\nthis occurs during the operation of an internal combustion engine. The reaction of gasoline and oxygen is\nexothermic. Some of this energy is given off as heat, and some does work pushing the piston in the cylinder.\nThe substances involved in the reaction are the system, and the engine and the rest of the universe are the\nsurroundings. The system loses energy by both heating and doing work on the surroundings, and its internal\nenergy decreases. (The engine is able to keep the car moving because this process is repeated many times per\nsecond while the engine is running.) We will consider how to determine the amount of work involved in a\nchemical or physical change in the chapter on thermodynamics.\n"]], ["block_2", ["This view of an internal combustion engine (http://openstax.org/l/16combustion) illustrates the conversion of\nenergy produced by the exothermic combustion reaction of a fuel such as gasoline into energy of motion.\n"]], ["block_3", ["As discussed, the relationship between internal energy, heat, and work can be represented as \u0394U = q + w.\nInternal energy is an example of a state function (or state variable), whereas heat and work are not state\nfunctions. The value of a state function depends only on the state that a system is in, and not on how that state\nis reached. If a quantity is not a state function, then its value does depend on how the state is reached. An\nexample of a state function is altitude or elevation. If you stand on the summit of Mt. Kilimanjaro, you are at an\naltitude of 5895 m, and it does not matter whether you hiked there or parachuted there. The distance you\ntraveled to the top of Kilimanjaro, however, is not a state function. You could climb to the summit by a direct\nroute or by a more roundabout, circuitous path (Figure 5.20). The distances traveled would differ (distance is\nnot a state function) but the elevation reached would be the same (altitude is a state function).\n"]], ["block_4", [" FIGURE 5.20 \nPaths X and Y represent two different routes to the summit of Mt. Kilimanjaro. Both have the same\n"]], ["block_5", ["change in elevation (altitude or elevation on a mountain is a state function; it does not depend on path), but they\nhave very different distances traveled (distance walked is not a state function; it depends on the path). (credit:\nmodification of work by Paul Shaffner)\n"]], ["block_6", ["Chemists ordinarily use a property known as enthalpy (H) to describe the thermodynamics of chemical and\nphysical processes. Enthalpy is defined as the sum of a system\u2019s internal energy (U) and the mathematical\nproduct of its pressure (P) and volume (V):\n"]], ["block_7", ["Enthalpy is also a state function. Enthalpy values for specific substances cannot be measured directly; only\nenthalpy changes for chemical or physical processes can be determined. For processes that take place at\nconstant pressure (a common condition for many chemical and physical changes), the enthalpy change ( \u0394 H) \nis:\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["LINK TO LEARNING\n"]], ["block_10", [{"image_0": "247_0.png", "coords": [130, 350, 481, 539]}]]], "page_248": [["block_0", ["The mathematical product P\u0394V represents work (w), namely, expansion or pressure-volume work as noted. By\ntheir definitions, the arithmetic signs of \u0394V and w will always be opposite:\n"]], ["block_1", ["Substituting this equation and the definition of internal energy into the enthalpy-change equation yields:\n"]], ["block_2", ["where qp is the heat of reaction under conditions of constant pressure.\n"]], ["block_3", ["And so, if a chemical or physical process is carried out at constant pressure with the only work done caused by\nexpansion or contraction, then the heat flow (qp) and enthalpy change (\u0394H) for the process are equal.\n"]], ["block_4", ["The heat given off when you operate a Bunsen burner is equal to the enthalpy change of the methane\ncombustion reaction that takes place, since it occurs at the essentially constant pressure of the atmosphere. On\nthe other hand, the heat produced by a reaction measured in a bomb calorimeter (Figure 5.17) is not equal to\n\u0394H because the closed, constant-volume metal container prevents the pressure from remaining constant (it\nmay increase or decrease if the reaction yields increased or decreased amounts of gaseous species). Chemists\nusually perform experiments under normal atmospheric conditions, at constant external pressure with q =\n\u0394H, which makes enthalpy the most convenient choice for determining heat changes for chemical reactions.\n"]], ["block_5", ["The following conventions apply when using \u0394H:\n"]], ["block_6", ["\u2022\nA negative value of an enthalpy change, \u0394H < 0, indicates an exothermic reaction; a positive value, \u0394H > 0,\nindicates an endothermic reaction. If the direction of a chemical equation is reversed, the arithmetic sign\nof its \u0394H is changed (a process that is endothermic in one direction is exothermic in the opposite\ndirection).\n"]], ["block_7", ["\u2022\nChemists use a thermochemical equation to represent the changes in both matter and energy. In a\nthermochemical equation, the enthalpy change of a reaction is shown as a \u0394H value following the equation\nfor the reaction. This \u0394H value indicates the amount of heat associated with the reaction involving the\nnumber of moles of reactants and products as shown in the chemical equation. For example, consider this\nequation:\n"]], ["block_8", ["\u2022\nThe enthalpy change of a reaction depends on the physical states of the reactants and products, so these\nmust be shown. For example, when 1 mole of hydrogen gas and\nmole of oxygen gas change to 1 mole of\n"]], ["block_9", ["This equation indicates that when 1 mole of hydrogen gas and\nmole of oxygen gas at some temperature\n"]], ["block_10", ["and pressure change to 1 mole of liquid water at the same temperature and pressure, 286 kJ of heat are\nreleased to the surroundings. If the coefficients of the chemical equation are multiplied by some factor, the\nenthalpy change must be multiplied by that same factor (\u0394H is an extensive property):\n"]], ["block_11", ["liquid water at the same temperature and pressure, 286 kJ of heat are released. If gaseous water forms,\nonly 242 kJ of heat are released.\n"]], ["block_12", [" 5.3 \u2022 Enthalpy \n 235 \n"]]], "page_249": [["block_0", [" 236 \n 5 \u2022 Thermochemistry \n"]], ["block_1", [" Writing Thermochemical Equations \n"]], ["block_2", ["When 0.0500 mol of HCl(aq) reacts with 0.0500 mol of NaOH(aq) to form 0.0500 mol of NaCl(aq), 2.9 kJ of heat\nare produced. Write a balanced thermochemical equation for the reaction of one mole of HCl.\n"]], ["block_3", [" Solution \n"]], ["block_4", ["For the reaction of 0.0500 mol acid (HCl), q = \u22122.9 kJ. The reactants are provided in stoichiometric amounts\n(same molar ratio as in the balanced equation), and so the amount of acid may be used to calculate a molar\nenthalpy change. Since \u0394H is an extensive property, it is proportional to the amount of acid neutralized:\n"]], ["block_5", ["The thermochemical equation is then\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["When 1.34 g Zn(s) reacts with 60.0 mL of 0.750 M HCl(aq), 3.14 kJ of heat are produced. Determine the\nenthalpy change per mole of zinc reacting for the reaction:\n"]], ["block_8", [" Answer: \n\u0394H = \u2212153 kJ\n"]], ["block_9", ["Be sure to take both stoichiometry and limiting reactants into account when determining the \u0394H for a\nchemical reaction.\n"]], ["block_10", [" Writing Thermochemical Equations \n"]], ["block_11", ["A gummy bear contains 2.67 g sucrose, C12H22O11. When it reacts with 7.19 g potassium chlorate, KClO3, 43.7\nkJ of heat are produced. Write a thermochemical equation for the reaction of one mole of sucrose:\n"]], ["block_12", [" Solution \n"]], ["block_13", ["Unlike the previous example exercise, this one does not involve the reaction of stoichiometric amounts of\nreactants, and so the limiting reactant must be identified (it limits the yield of the reaction and the amount of\nthermal energy produced or consumed).\n"]], ["block_14", ["The provided amounts of the two reactants are\n"]], ["block_15", ["The provided molar ratio of perchlorate-to-sucrose is then\n"]], ["block_16", ["The balanced equation indicates 8 mol KClO3 are required for reaction with 1 mol C12H22O11. Since the\nprovided amount of KClO3 is less than the stoichiometric amount, it is the limiting reactant and may be used to\ncompute the enthalpy change:\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["EXAMPLE 5.8\n"]], ["block_19", ["EXAMPLE 5.9\n"]]], "page_250": [["block_0", ["Because the equation, as written, represents the reaction of 8 mol KClO3, the enthalpy change is\n"]], ["block_1", ["The enthalpy change for this reaction is \u22125960 kJ, and the thermochemical equation is:\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["When 1.42 g of iron reacts with 1.80 g of chlorine, 3.22 g of FeCl2(s) and 8.60 kJ of heat is produced. What is the\nenthalpy change for the reaction when 1 mole of FeCl2(s) is produced?\n"]], ["block_4", [" Answer: \n\u0394H = \u2212338 kJ\n"]], ["block_5", ["Enthalpy changes are typically tabulated for reactions in which both the reactants and products are at the\nsame conditions. A standard state is a commonly accepted set of conditions used as a reference point for the\ndetermination of properties under other different conditions. For chemists, the IUPAC standard state refers to\nmaterials under a pressure of 1 bar and solutions at 1 M, and does not specify a temperature. Many\nthermochemical tables list values with a standard state of 1 atm. Because the \u0394H of a reaction changes very\nlittle with such small changes in pressure (1 bar = 0.987 atm), \u0394H values (except for the most precisely\nmeasured values) are essentially the same under both sets of standard conditions. We will include a\nsuperscripted \u201co\u201d in the enthalpy change symbol to designate standard state. Since the usual (but not\ntechnically standard) temperature is 298.15 K, this temperature will be assumed unless some other\ntemperature is specified. Thus, the symbol\nis used to indicate an enthalpy change for a process\n"]], ["block_6", ["occurring under these conditions. (The symbol \u0394H is used to indicate an enthalpy change for a reaction\noccurring under nonstandard conditions.)\n"]], ["block_7", ["The enthalpy changes for many types of chemical and physical processes are available in the reference\nliterature, including those for combustion reactions, phase transitions, and formation reactions. As we discuss\nthese quantities, it is important to pay attention to the extensive nature of enthalpy and enthalpy changes.\nSince the enthalpy change for a given reaction is proportional to the amounts of substances involved, it may be\nreported on that basis (i.e., as the \u0394H for specific amounts of reactants). However, we often find it more useful\nto divide one extensive property (\u0394H) by another (amount of substance), and report a per-amount intensive\nvalue of \u0394H, often \u201cnormalized\u201d to a per-mole basis. (Note that this is similar to determining the intensive\nproperty specific heat from the extensive property heat capacity, as seen previously.)\n"]], ["block_8", [" Standard Enthalpy of Combustion \n"]], ["block_9", [" Standard enthalpy of combustion \nis the enthalpy change when 1 mole of a substance burns\n"]], ["block_10", ["(combines vigorously with oxygen) under standard state conditions; it is sometimes called \u201cheat of\ncombustion.\u201d For example, the enthalpy of combustion of ethanol, \u22121366.8 kJ/mol, is the amount of heat\nproduced when one mole of ethanol undergoes complete combustion at 25 \u00b0C and 1 atmosphere pressure,\nyielding products also at 25 \u00b0C and 1 atm.\n"]], ["block_11", ["Enthalpies of combustion for many substances have been measured; a few of these are listed in Table 5.2.\nMany readily available substances with large enthalpies of combustion are used as fuels, including hydrogen,\ncarbon (as coal or charcoal), and hydrocarbons (compounds containing only hydrogen and carbon), such as\nmethane, propane, and the major components of gasoline.\n"]], ["block_12", [" 5.3 \u2022 Enthalpy \n 237 \n"]]], "page_251": [["block_0", [" 238 \n 5 \u2022 Thermochemistry \n"]], ["block_1", [" TABLE 5.2 \n"]], ["block_2", [" Using Enthalpy of Combustion \n"]], ["block_3", ["As Figure 5.21 suggests, the combustion of gasoline is a highly exothermic process. Let us determine the\napproximate amount of heat produced by burning 1.00 L of gasoline, assuming the enthalpy of combustion of\ngasoline is the same as that of isooctane, a common component of gasoline. The density of isooctane is 0.692\ng/mL.\n"]], ["block_4", [" Solution \n"]], ["block_5", ["Starting with a known amount (1.00 L of isooctane), we can perform conversions between units until we arrive\nat the desired amount of heat or energy. The enthalpy of combustion of isooctane provides one of the\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [" FIGURE 5.21 \nThe combustion of gasoline is very exothermic. (credit: modification of work by \u201cAlexEagle\u201d/Flickr)\n"]], ["block_8", [" Substance \n Combustion Reaction \n"]], ["block_9", ["carbon\n\u2212393.5\n"]], ["block_10", ["hydrogen\n\u2212285.8\n"]], ["block_11", ["magnesium\n\u2212601.6\n"]], ["block_12", ["sulfur\n\u2212296.8\n"]], ["block_13", ["carbon\nmonoxide\n\u2212283.0\n"]], ["block_14", ["methane\n\u2212890.8\n"]], ["block_15", ["acetylene\n\u22121301.1\n"]], ["block_16", ["ethanol\n\u22121366.8\n"]], ["block_17", ["methanol\n\u2212726.1\n"]], ["block_18", ["isooctane\n\u22125461\n"]], ["block_19", [{"image_0": "251_0.png", "coords": [90, 545, 522, 657]}]], ["block_20", ["EXAMPLE 5.10\n"]], ["block_21", ["Standard Molar Enthalpies of Combustion\n"]], ["block_22", [" Enthalpy of Combustion, \n"]]], "page_252": [["block_0", ["necessary conversions. Table 5.2 gives this value as \u22125460 kJ per 1 mole of isooctane (C8H18).\n"]], ["block_1", ["Using these data,\n"]], ["block_2", ["The combustion of 1.00 L of isooctane produces 33,100 kJ of heat. (This amount of energy is enough to melt\n99.2 kg, or about 218 lbs, of ice.)\n"]], ["block_3", ["Note: If you do this calculation one step at a time, you would find:\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["How much heat is produced by the combustion of 125 g of acetylene?\n"]], ["block_6", [" Answer: \n6.25\n10kJ\n"]], ["block_7", ["Chemistry in Everyday Life\n"]], ["block_8", [" Emerging Algae-Based Energy Technologies (Biofuels) \nAs reserves of fossil fuels diminish and become more costly to extract, the search is ongoing for\nreplacement fuel sources for the future. Among the most promising biofuels are those derived from algae\n(Figure 5.22). The species of algae used are nontoxic, biodegradable, and among the world\u2019s fastest growing\norganisms. About 50% of algal weight is oil, which can be readily converted into fuel such as biodiesel.\nAlgae can yield 26,000 gallons of biofuel per hectare\u2014much more energy per acre than other crops. Some\nstrains of algae can flourish in brackish water that is not usable for growing other crops. Algae can produce\nbiodiesel, biogasoline, ethanol, butanol, methane, and even jet fuel.\n"]], ["block_9", [" FIGURE 5.22 \n(a) Tiny algal organisms can be (b) grown in large quantities and eventually (c) turned into a\n"]], ["block_10", ["useful fuel such as biodiesel. (credit a: modification of work by Micah Sittig; credit b: modification of work by\nRobert Kerton; credit c: modification of work by John F. Williams)\n"]], ["block_11", [{"image_0": "252_0.png", "coords": [90, 476, 522, 629]}]], ["block_12", [" 5.3 \u2022 Enthalpy \n 239 \n"]]], "page_253": [["block_0", [" 240 \n 5 \u2022 Thermochemistry \n"]], ["block_1", ["Click here (http://openstax.org/l/16biofuel) to learn more about the process of creating algae biofuel.\n"]], ["block_2", [" Standard Enthalpy of Formation \n"]], ["block_3", ["A standard enthalpy of formation \nis an enthalpy change for a reaction in which exactly 1 mole of a pure\n"]], ["block_4", ["substance is formed from free elements in their most stable states under standard state conditions. These\nvalues are especially useful for computing or predicting enthalpy changes for chemical reactions that are\nimpractical or dangerous to carry out, or for processes for which it is difficult to make measurements. If we\nhave values for the appropriate standard enthalpies of formation, we can determine the enthalpy change for\nany reaction, which we will practice in the next section on Hess\u2019s law.\n"]], ["block_5", ["The standard enthalpy of formation of CO2(g) is \u2212393.5 kJ/mol. This is the enthalpy change for the exothermic\nreaction:\n"]], ["block_6", ["starting with the reactants at a pressure of 1 atm and 25 \u00b0C (with the carbon present as graphite, the most\nstable form of carbon under these conditions) and ending with one mole of CO2, also at 1 atm and 25 \u00b0C. For\nnitrogen dioxide, NO2(g),\nis 33.2 kJ/mol. This is the enthalpy change for the reaction:\n"]], ["block_7", ["A reaction equation with\nmole of N2 and 1 mole of O2 is correct in this case because the standard enthalpy of\n"]], ["block_8", ["formation always refers to 1 mole of product, NO2(g).\n"]], ["block_9", ["You will find a table of standard enthalpies of formation of many common substances in Appendix G. These\nvalues indicate that formation reactions range from highly exothermic (such as \u22122984 kJ/mol for the\nformation of P4O10) to strongly endothermic (such as +226.7 kJ/mol for the formation of acetylene, C2H2). By\ndefinition, the standard enthalpy of formation of an element in its most stable form is equal to zero under\n"]], ["block_10", ["3 For more on algal fuel, see http://www.theguardian.com/environment/2010/feb/13/algae-solve-pentagon-fuel-problem.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["According to the US Department of Energy, only 39,000 square kilometers (about 0.4% of the land mass of\nthe US or less than\nof the area used to grow corn) can produce enough algal fuel to replace all the\n"]], ["block_13", ["petroleum-based fuel used in the US. The cost of algal fuels is becoming more competitive\u2014for instance,\nthe US Air Force is producing jet fuel from algae at a total cost of under $5 per gallon.The process used to\nproduce algal fuel is as follows: grow the algae (which use sunlight as their energy source and CO2 as a raw\nmaterial); harvest the algae; extract the fuel compounds (or precursor compounds); process as necessary\n(e.g., perform a transesterification reaction to make biodiesel); purify; and distribute (Figure 5.23).\n"]], ["block_14", [" FIGURE 5.23 \nAlgae convert sunlight and carbon dioxide into oil that is harvested, extracted, purified, and\n"]], ["block_15", ["transformed into a variety of renewable fuels.\n"]], ["block_16", ["LINK TO LEARNING\n"]], ["block_17", [{"image_0": "253_0.png", "coords": [124, 154, 487, 286]}]]], "page_254": [["block_0", ["standard conditions, which is 1 atm for gases and 1 M for solutions.\n"]], ["block_1", [" Evaluating an Enthalpy of Formation \n"]], ["block_2", ["Ozone, O3(g), forms from oxygen, O2(g), by an endothermic process. Ultraviolet radiation is the source of the\nenergy that drives this reaction in the upper atmosphere. Assuming that both the reactants and products of the\nreaction are in their standard states, determine the standard enthalpy of formation,\nof ozone from the\n"]], ["block_3", ["following information:\n"]], ["block_4", [" Solution \n"]], ["block_5", ["elements in their standard states. Thus,\nfor O3(g) is the enthalpy change for the reaction:\n"]], ["block_6", ["For the formation of 2 mol of O3(g),\nThis ratio,\ncan be used as a conversion factor\n"]], ["block_7", ["to find the heat produced when 1 mole of O3(g) is formed, which is the enthalpy of formation for O3(g):\n"]], ["block_8", ["Therefore,\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["Hydrogen gas, H2, reacts explosively with gaseous chlorine, Cl2, to form hydrogen chloride, HCl(g). What is the\nenthalpy change for the reaction of 1 mole of H2(g) with 1 mole of Cl2(g) if both the reactants and products are\nat standard state conditions? The standard enthalpy of formation of HCl(g) is \u221292.3 kJ/mol.\n"]], ["block_11", [" Answer: \nFor the reaction\n"]], ["block_12", [" Writing Reaction Equations for \n"]], ["block_13", ["Write the heat of formation reaction equations for:\n"]], ["block_14", ["(a) C2H5OH(l)\n"]], ["block_15", ["(b) Ca3(PO4)2(s)\n"]], ["block_16", [" Solution \n"]], ["block_17", ["Remembering that\nreaction equations are for forming 1 mole of the compound from its constituent\n"]], ["block_18", ["elements under standard conditions, we have:\n"]], ["block_19", ["(a)\n"]], ["block_20", ["(b)\n"]], ["block_21", ["Note: The standard state of carbon is graphite, and phosphorus exists as P4.\n"]], ["block_22", [" Check Your Learning \n"]], ["block_23", ["Write the heat of formation reaction equations for:\n"]], ["block_24", ["is the enthalpy change for the formation of one mole of a substance in its standard state from the\n"]], ["block_25", ["EXAMPLE 5.11\n"]], ["block_26", ["EXAMPLE 5.12\n"]], ["block_27", [" 5.3 \u2022 Enthalpy \n 241 \n"]]], "page_255": [["block_0", [" 242 \n 5 \u2022 Thermochemistry \n"]], ["block_1", ["This type of calculation usually involves the use of Hess\u2019s law , which states: If a process can be written as the\nsum of several stepwise processes, the enthalpy change of the total process equals the sum of the enthalpy\nchanges of the various steps. Hess\u2019s law is valid because enthalpy is a state function: Enthalpy changes depend\nonly on where a chemical process starts and ends, but not on the path it takes from start to finish. For example,\nwe can think of the reaction of carbon with oxygen to form carbon dioxide as occurring either directly or by a\ntwo-step process. The direct process is written:\n"]], ["block_2", ["(a) C2H5OC2H5(l)\n"]], ["block_3", ["(b) Na2CO3(s)\n"]], ["block_4", [" Answer: \n"]], ["block_5", ["(a)\n(b)\n"]], ["block_6", [" Hess\u2019s Law \n"]], ["block_7", ["There are two ways to determine the amount of heat involved in a chemical change: measure it experimentally,\nor calculate it from other experimentally determined enthalpy changes. Some reactions are difficult, if not\nimpossible, to investigate and make accurate measurements for experimentally. And even when a reaction is\nnot hard to perform or measure, it is convenient to be able to determine the heat involved in a reaction without\nhaving to perform an experiment.\n"]], ["block_8", ["In the two-step process, first carbon monoxide is formed:\n"]], ["block_9", ["Then, carbon monoxide reacts further to form carbon dioxide:\n"]], ["block_10", ["The equation describing the overall reaction is the sum of these two chemical changes:\n"]], ["block_11", ["Because the CO produced in Step 1 is consumed in Step 2, the net change is:\n"]], ["block_12", ["According to Hess\u2019s law, the enthalpy change of the reaction will equal the sum of the enthalpy changes of the\nsteps.\n"]], ["block_13", ["The result is shown in Figure 5.24. We see that \u0394H of the overall reaction is the same whether it occurs in one\nstep or two. This finding (overall \u0394H for the reaction = sum of \u0394H values for reaction \u201csteps\u201d in the overall\nreaction) is true in general for chemical and physical processes.\n"]], ["block_14", [" Access for free at openstax.org \n"]]], "page_256": [["block_0", [" FIGURE 5.24 \nThe formation of CO2(g) from its elements can be thought of as occurring in two steps, which sum to\n"]], ["block_1", ["the overall reaction, as described by Hess\u2019s law. The horizontal blue lines represent enthalpies. For an exothermic\nprocess, the products are at lower enthalpy than are the reactants.\n"]], ["block_2", ["Before we further practice using Hess\u2019s law, let us recall two important features of \u0394H.\n"]], ["block_3", [" Stepwise Calculation of \n Using Hess\u2019s Law \n"]], ["block_4", ["Determine the enthalpy of formation,\nof FeCl3(s) from the enthalpy changes of the following two-step\n"]], ["block_5", ["process that occurs under standard state conditions:\n"]], ["block_6", [" Solution \n"]], ["block_7", ["We are trying to find the standard enthalpy of formation of FeCl3(s), which is equal to \u0394H\u00b0 for the reaction:\n"]], ["block_8", ["1.\n\u0394H is directly proportional to the quantities of reactants or products. For example, the enthalpy change for\nthe reaction forming 1 mole of NO2(g) is +33.2 kJ:\n"]], ["block_9", ["2.\n\u0394H for a reaction in one direction is equal in magnitude and opposite in sign to \u0394H for the reaction in the\nreverse direction. For example, given that:\n"]], ["block_10", ["When 2 moles of NO2 (twice as much) are formed, the \u0394H will be twice as large:\n"]], ["block_11", ["In general, if we multiply or divide an equation by a number, then the enthalpy change should also be\nmultiplied or divided by the same number.\n"]], ["block_12", ["Then, for the \u201creverse\u201d reaction, the enthalpy change is also \u201creversed\u201d:\n"]], ["block_13", ["EXAMPLE 5.13\n"]], ["block_14", [{"image_0": "256_0.png", "coords": [130, 57, 481, 250]}]], ["block_15", [" 5.3 \u2022 Enthalpy \n 243 \n"]]], "page_257": [["block_0", [" 244 \n 5 \u2022 Thermochemistry \n"]], ["block_1", ["(i)\n"]], ["block_2", ["(ii)\n"]], ["block_3", ["(iii)\n"]], ["block_4", ["(iv)\n"]], ["block_5", ["Looking at the reactions, we see that the reaction for which we want to find \u0394H\u00b0 is the sum of the two reactions\nwith known \u0394H values, so we must sum their \u0394Hs:\n"]], ["block_6", ["The enthalpy of formation,\nof FeCl3(s) is \u2212399.5 kJ/mol.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["Calculate \u0394H for the process:\n"]], ["block_9", ["from the following information:\n"]], ["block_10", [" Answer: \n66.4 kJ\n"]], ["block_11", ["Here is a less straightforward example that illustrates the thought process involved in solving many Hess\u2019s law\nproblems. It shows how we can find many standard enthalpies of formation (and other values of \u0394H) if they are\ndifficult to determine experimentally.\n"]], ["block_12", [" A More Challenging Problem Using Hess\u2019s Law \n"]], ["block_13", ["Chlorine monofluoride can react with fluorine to form chlorine trifluoride:\n"]], ["block_14", ["Use the reactions here to determine the \u0394H\u00b0 for reaction (i):\n"]], ["block_15", [" Solution \n"]], ["block_16", ["Our goal is to manipulate and combine reactions (ii), (iii), and (iv) such that they add up to reaction (i). Going\nfrom left to right in (i), we first see that ClF(g) is needed as a reactant. This can be obtained by multiplying\nreaction (iii) by\nwhich means that the \u0394H\u00b0 change is also multiplied by\n"]], ["block_17", ["Next, we see that F2 is also needed as a reactant. To get this, reverse and halve reaction (ii), which means that\nthe \u0394H\u00b0 changes sign and is halved:\n"]], ["block_18", ["To get ClF3 as a product, reverse (iv), changing the sign of \u0394H\u00b0:\n"]], ["block_19", [" Access for free at openstax.org \n"]], ["block_20", ["EXAMPLE 5.14\n"]]], "page_258": [["block_0", ["(i)\n"]], ["block_1", ["(ii)\n"]], ["block_2", ["(iii)\n"]], ["block_3", ["(iv)\n"]], ["block_4", ["(v)\n"]], ["block_5", ["Now check to make sure that these reactions add up to the reaction we want:\n"]], ["block_6", ["Reactants\nand\ncancel out product O2; product\ncancels reactant\nand reactant\n"]], ["block_7", ["is cancelled by products\nand OF2. This leaves only reactants ClF(g) and F2(g) and product ClF3(g), which\n"]], ["block_8", ["are what we want. Since summing these three modified reactions yields the reaction of interest, summing the\nthree modified \u0394H\u00b0 values will give the desired \u0394H\u00b0:\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["Aluminum chloride can be formed from its elements:\n"]], ["block_11", ["Use the reactions here to determine the \u0394H\u00b0 for reaction (i):\n"]], ["block_12", [" Answer: \n\u22121407 kJ\n"]], ["block_13", ["We also can use Hess\u2019s law to determine the enthalpy change of any reaction if the corresponding enthalpies of\nformation of the reactants and products are available. The stepwise reactions we consider are: (i)\ndecompositions of the reactants into their component elements (for which the enthalpy changes are\nproportional to the negative of the enthalpies of formation of the reactants), followed by (ii) re-combinations of\nthe elements to give the products (with the enthalpy changes proportional to the enthalpies of formation of the\nproducts). The standard enthalpy change of the overall reaction is therefore equal to: (ii) the sum of the\nstandard enthalpies of formation of all the products plus (i) the sum of the negatives of the standard enthalpies\nof formation of the reactants. This is usually rearranged slightly to be written as follows, with \u2211 representing\n\u201cthe sum of\u201d and n standing for the stoichiometric coefficients:\n"]], ["block_14", ["The following example shows in detail why this equation is valid, and how to use it to calculate the enthalpy\nchange for a reaction of interest.\n"]], ["block_15", [" Using Hess\u2019s Law \n"]], ["block_16", ["What is the standard enthalpy change for the reaction:\n"]], ["block_17", ["EXAMPLE 5.15\n"]], ["block_18", [" 5.3 \u2022 Enthalpy \n 245 \n"]]], "page_259": [["block_0", [" 246 \n 5 \u2022 Thermochemistry \n"]], ["block_1", [" Solution: Using the Equation \n"]], ["block_2", ["Use the special form of Hess\u2019s law given previously, and values from Appendix G:\n"]], ["block_3", [" Solution: Supporting Why the General Equation Is Valid \n"]], ["block_4", ["Alternatively, we can write this reaction as the sum of the decompositions of 3NO2(g) and 1H2O(l) into their\nconstituent elements, and the formation of 2HNO3(aq) and 1NO(g) from their constituent elements. Writing out\nthese reactions, and noting their relationships to the\nvalues for these compounds (from Appendix G ), we\n"]], ["block_5", ["have:\n"]], ["block_6", ["Summing these reaction equations gives the reaction we are interested in:\n"]], ["block_7", ["Summing their enthalpy changes gives the value we want to determine:\n"]], ["block_8", ["So the standard enthalpy change for this reaction is \u0394H\u00b0 = \u2212138.4 kJ.\n"]], ["block_9", ["Note that this result was obtained by (1) multiplying the\nof each product by its stoichiometric coefficient\n"]], ["block_10", ["and summing those values, (2) multiplying the\nof each reactant by its stoichiometric coefficient and\n"]], ["block_11", ["summing those values, and then (3) subtracting the result found in (2) from the result found in (1). This is also\nthe procedure in using the general equation, as shown.\n"]], ["block_12", [" Check Your Learning \n"]], ["block_13", ["Calculate the heat of combustion of 1 mole of ethanol, C2H5OH(l), when H2O(l) and CO2(g) are formed. Use the\nfollowing enthalpies of formation: C2H5OH(l), \u2212278 kJ/mol; H2O(l), \u2212286 kJ/mol; and CO2(g), \u2212394 kJ/mol.\n"]], ["block_14", [" Answer: \n\u22121368 kJ/mol\n"]], ["block_15", [" Access for free at openstax.org \n"]]], "page_260": [["block_0", [" Key Terms \n"]], ["block_1", [" bomb calorimeter \ndevice designed to measure the\n"]], ["block_2", [" calorie (cal) \nunit of heat or other energy; the\n"]], ["block_3", [" calorimeter \ndevice used to measure the amount of\n"]], ["block_4", [" calorimetry \nprocess of measuring the amount of\n"]], ["block_5", [" chemical thermodynamics \narea of science that\n"]], ["block_6", [" endothermic process \nchemical reaction or\n"]], ["block_7", [" energy \ncapacity to supply heat or do work\n"]], ["block_8", [" enthalpy (H) \nsum of a system\u2019s internal energy and\n"]], ["block_9", [" enthalpy change ( \u0394 H) \nheat released or absorbed\n"]], ["block_10", [" exothermic process \nchemical reaction or physical\n"]], ["block_11", [" expansion work (pressure-volume work) \nwork\n"]], ["block_12", [" first law of thermodynamics \ninternal energy of a\n"]], ["block_13", [" heat (q) \ntransfer of thermal energy between two\n"]], ["block_14", [" heat capacity (C) \nextensive property of a body of\n"]], ["block_15", [" Hess\u2019s law \nif a process can be represented as the\n"]], ["block_16", [" hydrocarbon \ncompound composed only of\n"]], ["block_17", [" internal energy (U) \ntotal of all possible kinds of\n"]], ["block_18", ["energy change for processes occurring under\nconditions of constant volume; commonly used\nfor reactions involving solid and gaseous\nreactants or products\n"]], ["block_19", ["amount of energy required to raise 1 gram of\nwater by 1 degree Celsius; 1 cal is defined as\n4.184 J\n"]], ["block_20", ["heat absorbed or released in a chemical or\nphysical process\n"]], ["block_21", ["heat involved in a chemical or physical process\n"]], ["block_22", ["deals with the relationships between heat, work,\nand all forms of energy associated with chemical\nand physical processes\n"]], ["block_23", ["physical change that absorbs heat\n"]], ["block_24", ["the mathematical product of its pressure and\nvolume\n"]], ["block_25", ["by a system under constant pressure during a\nchemical or physical process\n"]], ["block_26", ["change that releases heat\n"]], ["block_27", ["done as a system expands or contracts against\nexternal pressure\n"]], ["block_28", ["system changes due to heat flow in or out of the\nsystem or work done on or by the system\n"]], ["block_29", ["bodies\n"]], ["block_30", ["matter that represents the quantity of heat\nrequired to increase its temperature by 1 degree\nCelsius (or 1 kelvin)\n"]], ["block_31", ["sum of several steps, the enthalpy change of the\nprocess equals the sum of the enthalpy changes\nof the steps\n"]], ["block_32", ["hydrogen and carbon; the major component of\nfossil fuels\n"]], ["block_33", ["energy present in a substance or substances\n"]], ["block_34", [" joule (J) \nSI unit of energy; 1 joule is the kinetic\n"]], ["block_35", [" kinetic energy \nenergy of a moving body, in joules,\n"]], ["block_36", [" nutritional calorie (Calorie) \nunit used for\n"]], ["block_37", [" potential energy \nenergy of a particle or system of\n"]], ["block_38", [" specific heat capacity (c) \nintensive property of a\n"]], ["block_39", [" standard enthalpy of combustion \nheat\n"]], ["block_40", [" standard enthalpy of formation \nenthalpy\n"]], ["block_41", [" standard state \nset of physical conditions as\n"]], ["block_42", [" state function \nproperty depending only on the\n"]], ["block_43", [" surroundings \nall matter other than the system\n"]], ["block_44", [" system \nportion of matter undergoing a chemical or\n"]], ["block_45", [" temperature \nintensive property of matter that is a\n"]], ["block_46", [" thermal energy \nkinetic energy associated with the\n"]], ["block_47", [" thermochemistry \nstudy of measuring the amount\n"]], ["block_48", [" work (w) \nenergy transfer due to changes in\n"]], ["block_49", ["energy of an object with a mass of 2 kilograms\nmoving with a velocity of 1 meter per second, 1 J\n= 1 kg m/s and 4.184 J = 1 cal\n"]], ["block_50", ["equal to\n(where m = mass and v = velocity)\n"]], ["block_51", ["quantifying energy provided by digestion of\nfoods, defined as 1000 cal or 1 kcal\n"]], ["block_52", ["particles derived from relative position,\ncomposition, or condition\n"]], ["block_53", ["substance that represents the quantity of heat\nrequired to raise the temperature of 1 gram of the\nsubstance by 1 degree Celsius (or 1 kelvin)\n"]], ["block_54", ["released when one mole of a compound\nundergoes complete combustion under standard\nconditions\n"]], ["block_55", ["change of a chemical reaction in which 1 mole of\na pure substance is formed from its elements in\ntheir most stable states under standard state\nconditions\n"]], ["block_56", ["accepted as common reference conditions for\nreporting thermodynamic properties; 1 bar of\npressure, and solutions at 1 molar\nconcentrations, usually at a temperature of\n298.15 K\n"]], ["block_57", ["state of a system, and not the path taken to reach\nthat state\n"]], ["block_58", ["being studied\n"]], ["block_59", ["physical change being studied\n"]], ["block_60", ["quantitative measure of \u201chotness\u201d and \u201ccoldness\u201d\n"]], ["block_61", ["random motion of atoms and molecules\n"]], ["block_62", ["of heat absorbed or released during a chemical\nreaction or a physical change\n"]], ["block_63", ["external, macroscopic variables such as pressure\nand volume; or causing matter to move against an\nopposing force\n"]], ["block_64", [" 5 \u2022 Key Terms \n 247 \n"]]], "page_261": [["block_0", [" 248 \n 5 \u2022 Key Equations \n"]], ["block_1", [" Key Equations \n"]], ["block_2", [" Summary \n"]], ["block_3", [" 5.1 Energy Basics \n"]], ["block_4", ["Energy is the capacity to supply heat or do work\n(applying a force to move matter). Kinetic energy\n(KE) is the energy of motion; potential energy is\nenergy due to relative position, composition, or\ncondition. When energy is converted from one form\ninto another, energy is neither created nor destroyed\n(law of conservation of energy or first law of\nthermodynamics).\n"]], ["block_5", ["The thermal energy of matter is due to the kinetic\nenergies of its constituent atoms or molecules.\nTemperature is an intensive property of matter\nreflecting hotness or coldness that increases as the\naverage kinetic energy increases. Heat is the\ntransfer of thermal energy between objects at\ndifferent temperatures. Chemical and physical\nprocesses can absorb heat (endothermic) or release\nheat (exothermic). The SI unit of energy, heat, and\nwork is the joule (J).\n"]], ["block_6", ["Specific heat and heat capacity are measures of the\nenergy needed to change the temperature of a\nsubstance or object. The amount of heat absorbed or\nreleased by a substance depends directly on the type\nof substance, its mass, and the temperature change\nit undergoes.\n"]], ["block_7", [" 5.2 Calorimetry \n"]], ["block_8", ["Calorimetry is used to measure the amount of\nthermal energy transferred in a chemical or physical\nprocess. This requires careful measurement of the\ntemperature change that occurs during the process\n"]], ["block_9", [" Exercises \n"]], ["block_10", [" 5.1 Energy Basics \n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", [" 1 . A burning match and a bonfire may have the same temperature, yet you would not sit around a burning\n"]], ["block_13", [" 2 . Prepare a table identifying several energy transitions that take place during the typical operation of an\n"]], ["block_14", [" 3 . Explain the difference between heat capacity and specific heat of a substance.\n 4 . Calculate the heat capacity, in joules and in calories per degree, of the following:\n"]], ["block_15", ["match on a fall evening to stay warm. Why not?\n"]], ["block_16", ["automobile.\n"]], ["block_17", ["(a) 28.4 g of water\n(b) 1.00 oz of lead\n"]], ["block_18", ["and the masses of the system and surroundings.\nThese measured quantities are then used to\ncompute the amount of heat produced or consumed\nin the process using known mathematical relations.\n"]], ["block_19", ["Calorimeters are designed to minimize energy\nexchange between their contents and the external\nenvironment. They range from simple coffee cup\ncalorimeters used by introductory chemistry\nstudents to sophisticated bomb calorimeters used to\ndetermine the energy content of food.\n"]], ["block_20", [" 5.3 Enthalpy \n"]], ["block_21", ["If a chemical change is carried out at constant\npressure and the only work done is caused by\nexpansion or contraction, q for the change is called\nthe enthalpy change with the symbol \u0394H, or\nfor\n"]], ["block_22", ["reactions occurring under standard state conditions\nat 298 K. The value of \u0394H for a reaction in one\ndirection is equal in magnitude, but opposite in sign,\nto \u0394H for the reaction in the opposite direction, and\n\u0394H is directly proportional to the quantity of\nreactants and products. The standard enthalpy of\nformation,\nis the enthalpy change\n"]], ["block_23", ["accompanying the formation of 1 mole of a\nsubstance from the elements in their most stable\nstates at 1 bar and 298.15 K. If the enthalpies of\nformation are available for the reactants and\nproducts of a reaction, the enthalpy change can be\ncalculated using Hess\u2019s law: If a process can be\nwritten as the sum of several stepwise processes, the\nenthalpy change of the total process equals the sum\nof the enthalpy changes of the various steps.\n"]]], "page_262": [["block_0", [" 8 . How much would the temperature of 275 g of water increase if 36.5 kJ of heat were added?\n 9 . If 14.5 kJ of heat were added to 485 g of liquid water, how much would its temperature increase?\n 10 . A piece of unknown substance weighs 44.7 g and requires 2110 J to increase its temperature from 23.2 \u00b0C\n"]], ["block_1", [" 11 . A piece of unknown solid substance weighs 437.2 g, and requires 8460 J to increase its temperature from\n"]], ["block_2", [" 12 . An aluminum kettle weighs 1.05 kg.\n"]], ["block_3", [" 13 . Most people find waterbeds uncomfortable unless the water temperature is maintained at about 85 \u00b0F.\n"]], ["block_4", [" 5.2 Calorimetry \n"]], ["block_5", [" 14 . A 500-mL bottle of water at room temperature and a 2-L bottle of water at the same temperature were\n"]], ["block_6", [" 15 . Would the amount of heat measured for the reaction in Example 5.5 be greater, lesser, or remain the same\n"]], ["block_7", [" 16 . Would the amount of heat absorbed by the dissolution in Example 5.6 appear greater, lesser, or remain the\n"]], ["block_8", [" 17 . Would the amount of heat absorbed by the dissolution in Example 5.6 appear greater, lesser, or remain the\n"]], ["block_9", [" 18 . How many milliliters of water at 23 \u00b0C with a density of 1.00 g/mL must be mixed with 180 mL (about 6 oz)\n"]], ["block_10", [" 19 . How much will the temperature of a cup (180 g) of coffee at 95 \u00b0C be reduced when a 45 g silver spoon\n"]], ["block_11", [" 5 . Calculate the heat capacity, in joules and in calories per degree, of the following:\n"]], ["block_12", [" 6 . How much heat, in joules and in calories, must be added to a 75.0\u2013g iron block with a specific heat of\n"]], ["block_13", [" 7 . How much heat, in joules and in calories, is required to heat a 28.4-g (1-oz) ice cube from \u221223.0 \u00b0C to \u22121.0\n"]], ["block_14", ["(a) 45.8 g of nitrogen gas\n(b) 1.00 pound of aluminum metal\n"]], ["block_15", ["0.449 J/g \u00b0C to increase its temperature from 25 \u00b0C to its melting temperature of 1535 \u00b0C?\n"]], ["block_16", ["\u00b0C?\n"]], ["block_17", ["to 89.6 \u00b0C.\n(a) What is the specific heat of the substance?\n(b) If it is one of the substances found in Table 5.1, what is its likely identity?\n"]], ["block_18", ["19.3 \u00b0C to 68.9 \u00b0C.\n(a) What is the specific heat of the substance?\n(b) If it is one of the substances found in Table 5.1, what is its likely identity?\n"]], ["block_19", ["(a) What is the heat capacity of the kettle?\n(b) How much heat is required to increase the temperature of this kettle from 23.0 \u00b0C to 99.0 \u00b0C?\n(c) How much heat is required to heat this kettle from 23.0 \u00b0C to 99.0 \u00b0C if it contains 1.25 L of water\n(density of 0.997 g/mL and a specific heat of 4.184 J/g \u00b0C)?\n"]], ["block_20", ["Unless it is heated, a waterbed that contains 892 L of water cools from 85 \u00b0F to 72 \u00b0F in 24 hours. Estimate\nthe amount of electrical energy required over 24 hours, in kWh, to keep the bed from cooling. Note that 1\nkilowatt-hour (kWh) = 3.6\n10J, and assume that the density of water is 1.0 g/mL (independent of\n"]], ["block_21", ["temperature). What other assumptions did you make? How did they affect your calculated result (i.e., were\nthey likely to yield \u201cpositive\u201d or \u201cnegative\u201d errors)?\n"]], ["block_22", ["placed in a refrigerator. After 30 minutes, the 500-mL bottle of water had cooled to the temperature of the\nrefrigerator. An hour later, the 2-L of water had cooled to the same temperature. When asked which\nsample of water lost the most heat, one student replied that both bottles lost the same amount of heat\nbecause they started at the same temperature and finished at the same temperature. A second student\nthought that the 2-L bottle of water lost more heat because there was more water. A third student believed\nthat the 500-mL bottle of water lost more heat because it cooled more quickly. A fourth student thought\nthat it was not possible to tell because we do not know the initial temperature and the final temperature of\nthe water. Indicate which of these answers is correct and describe the error in each of the other answers.\n"]], ["block_23", ["if we used a calorimeter that was a poorer insulator than a coffee cup calorimeter? Explain your answer.\n"]], ["block_24", ["same if the experimenter used a calorimeter that was a poorer insulator than a coffee cup calorimeter?\nExplain your answer.\n"]], ["block_25", ["same if the heat capacity of the calorimeter were taken into account? Explain your answer.\n"]], ["block_26", ["of coffee at 95 \u00b0C so that the resulting combination will have a temperature of 60 \u00b0C? Assume that coffee\nand water have the same density and the same specific heat.\n"]], ["block_27", ["(specific heat 0.24 J/g \u00b0C) at 25 \u00b0C is placed in the coffee and the two are allowed to reach the same\ntemperature? Assume that the coffee has the same density and specific heat as water.\n"]], ["block_28", [" 5 \u2022 Exercises \n 249 \n"]]], "page_263": [["block_0", [" 250 \n 5 \u2022 Exercises \n"]], ["block_1", [" 20 . A 45-g aluminum spoon (specific heat 0.88 J/g \u00b0C) at 24 \u00b0C is placed in 180 mL (180 g) of coffee at 85 \u00b0C\n"]], ["block_2", [" 21 . The temperature of the cooling water as it leaves the hot engine of an automobile is 240 \u00b0F. After it passes\n"]], ["block_3", [" 22 . A 70.0-g piece of metal at 80.0 \u00b0C is placed in 100 g of water at 22.0 \u00b0C contained in a calorimeter like that\n"]], ["block_4", [" 23 . If a reaction produces 1.506 kJ of heat, which is trapped in 30.0 g of water initially at 26.5 \u00b0C in a\n"]], ["block_5", [" 24 . A 0.500-g sample of KCl is added to 50.0 g of water in a calorimeter (Figure 5.12). If the temperature\n"]], ["block_6", [" 25 . Dissolving 3.0 g of CaCl2(s) in 150.0 g of water in a calorimeter (Figure 5.12) at 22.4 \u00b0C causes the\n"]], ["block_7", [" 26 . When 50.0 g of 0.200 M NaCl(aq) at 24.1 \u00b0C is added to 100.0 g of 0.100 M AgNO3(aq) at 24.1 \u00b0C in a\n"]], ["block_8", [" 27 . The addition of 3.15 g of Ba(OH)2\u00b78H2O to a solution of 1.52 g of NH4SCN in 100 g of water in a calorimeter\n"]], ["block_9", [" 28 . The reaction of 50 mL of acid and 50 mL of base described in Example 5.5 increased the temperature of\n"]], ["block_10", [" 29 . If the 3.21 g of NH4NO3 in Example 5.6 were dissolved in 100.0 g of water under the same conditions, how\n"]], ["block_11", [" 30 . When 1.0 g of fructose, C6H12O6(s), a sugar commonly found in fruits, is burned in oxygen in a bomb\n"]], ["block_12", [" 31 . When a 0.740-g sample of trinitrotoluene (TNT), C7H5N2O6, is burned in a bomb calorimeter, the\n"]], ["block_13", [" 32 . One method of generating electricity is by burning coal to heat water, which produces steam that drives an\n"]], ["block_14", [" 33 . The amount of fat recommended for someone with a daily diet of 2000 Calories is 65 g. What percent of\n"]], ["block_15", [" 34 . A teaspoon of the carbohydrate sucrose (common sugar) contains 16 Calories (16 kcal). What is the mass\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["and the temperature of the two become equal.\n(a) What is the final temperature when the two become equal? Assume that coffee has the same specific\nheat as water.\n(b) The first time a student solved this problem she got an answer of 88 \u00b0C. Explain why this is clearly an\nincorrect answer.\n"]], ["block_18", ["through the radiator it has a temperature of 175 \u00b0F. Calculate the amount of heat transferred from the\nengine to the surroundings by one gallon of water with a specific heat of 4.184 J/g \u00b0C.\n"]], ["block_19", ["shown in Figure 5.12. The metal and water come to the same temperature at 24.6 \u00b0C. How much heat did\nthe metal give up to the water? What is the specific heat of the metal?\n"]], ["block_20", ["calorimeter like that in Figure 5.12, what is the resulting temperature of the water?\n"]], ["block_21", ["decreases by 1.05 \u00b0C, what is the approximate amount of heat involved in the dissolution of the KCl,\nassuming the specific heat of the resulting solution is 4.18 J/g \u00b0C? Is the reaction exothermic or\nendothermic?\n"]], ["block_22", ["temperature to rise to 25.8 \u00b0C. What is the approximate amount of heat involved in the dissolution,\nassuming the specific heat of the resulting solution is 4.18 J/g \u00b0C? Is the reaction exothermic or\nendothermic?\n"]], ["block_23", ["calorimeter, the temperature increases to 25.2 \u00b0C as AgCl(s) forms. Assuming the specific heat of the\nsolution and products is 4.20 J/g \u00b0C, calculate the approximate amount of heat in joules produced.\n"]], ["block_24", ["caused the temperature to fall by 3.1 \u00b0C. Assuming the specific heat of the solution and products is 4.20\nJ/g \u00b0C, calculate the approximate amount of heat absorbed by the reaction, which can be represented by\nthe following equation:\nBa(OH)2\u00b78H2O(s) + 2NH4SCN(aq) \u27f6 Ba(SCN)2(aq) + 2NH3(aq) + 10H2O(l)\n"]], ["block_25", ["the solution by 6.9 \u00baC. How much would the temperature have increased if 100 mL of acid and 100 mL of\nbase had been used in the same calorimeter starting at the same temperature of 22.0 \u00baC? Explain your\nanswer.\n"]], ["block_26", ["much would the temperature change? Explain your answer.\n"]], ["block_27", ["calorimeter, the temperature of the calorimeter increases by 1.58 \u00b0C. If the heat capacity of the\ncalorimeter and its contents is 9.90 kJ/\u00b0C, what is q for this combustion?\n"]], ["block_28", ["temperature increases from 23.4 \u00b0C to 26.9 \u00b0C. The heat capacity of the calorimeter is 534 J/\u00b0C, and it\ncontains 675 mL of water. How much heat was produced by the combustion of the TNT sample?\n"]], ["block_29", ["electric generator. To determine the rate at which coal is to be fed into the burner in this type of plant, the\nheat of combustion per ton of coal must be determined using a bomb calorimeter. When 1.00 g of coal is\nburned in a bomb calorimeter (Figure 5.17), the temperature increases by 1.48 \u00b0C. If the heat capacity of\nthe calorimeter is 21.6 kJ/\u00b0C, determine the heat produced by combustion of a ton of coal (2.000\n10\n"]], ["block_30", ["pounds).\n"]], ["block_31", ["the calories in this diet would be supplied by this amount of fat if the average number of Calories for fat is\n9.1 Calories/g?\n"]], ["block_32", ["of one teaspoon of sucrose if the average number of Calories for carbohydrates is 4.1 Calories/g?\n"]]], "page_264": [["block_0", [" 35 . What is the maximum mass of carbohydrate in a 6-oz serving of diet soda that contains less than 1 Calorie\n"]], ["block_1", [" 36 . A pint of premium ice cream can contain 1100 Calories. What mass of fat, in grams and pounds, must be\n"]], ["block_2", [" 37 . A serving of a breakfast cereal contains 3 g of protein, 18 g of carbohydrates, and 6 g of fat. What is the\n"]], ["block_3", [" 38 . Which is the least expensive source of energy in kilojoules per dollar: a box of breakfast cereal that weighs\n"]], ["block_4", [" 5.3 Enthalpy \n"]], ["block_5", [" 39 . Explain how the heat measured in Example 5.5 differs from the enthalpy change for the exothermic\n"]], ["block_6", [" 40 . Using the data in the check your learning section of Example 5.5, calculate \u0394H in kJ/mol of AgNO3(aq) for\n"]], ["block_7", [" 41 . Calculate the enthalpy of solution (\u0394H for the dissolution) per mole of NH4NO3 under the conditions\n"]], ["block_8", [" 42 . Calculate \u0394H for the reaction described by the equation. (Hint: Use the value for the approximate amount\n"]], ["block_9", [" 43 . Calculate the enthalpy of solution (\u0394H for the dissolution) per mole of CaCl2 (refer to Exercise 5.25).\n 44 . Although the gas used in an oxyacetylene torch (Figure 5.7) is essentially pure acetylene, the heat\n"]], ["block_10", [" 45 . How much heat is produced by burning 4.00 moles of acetylene under standard state conditions?\n 46 . How much heat is produced by combustion of 125 g of methanol under standard state conditions?\n 47 . How many moles of isooctane must be burned to produce 100 kJ of heat under standard state conditions?\n 48 . What mass of carbon monoxide must be burned to produce 175 kJ of heat under standard state\n"]], ["block_11", [" 49 . When 2.50 g of methane burns in oxygen, 125 kJ of heat is produced. What is the enthalpy of combustion\n"]], ["block_12", [" 50 . How much heat is produced when 100 mL of 0.250 M HCl (density, 1.00 g/mL) and 200 mL of 0.150 M\n"]], ["block_13", [" 51 . A sample of 0.562 g of carbon is burned in oxygen in a bomb calorimeter, producing carbon dioxide.\n"]], ["block_14", [" 52 . Before the introduction of chlorofluorocarbons, sulfur dioxide (enthalpy of vaporization, 6.00 kcal/mol)\n"]], ["block_15", [" 53 . Homes may be heated by pumping hot water through radiators. What mass of water will provide the same\n"]], ["block_16", ["per can if the average number of Calories for carbohydrates is 4.1 Calories/g?\n"]], ["block_17", ["produced in the body to store an extra 1.1\n10Calories if the average number of Calories for fat is\n"]], ["block_18", ["9.1 Calories/g?\n"]], ["block_19", ["Calorie content of a serving of this cereal if the average number of Calories for fat is 9.1 Calories/g, for\ncarbohydrates is 4.1 Calories/g, and for protein is 4.1 Calories/g?\n"]], ["block_20", ["32 ounces and costs $4.23, or a liter of isooctane (density, 0.6919 g/mL) that costs $0.45? Compare the\nnutritional value of the cereal with the heat produced by combustion of the isooctane under standard\nconditions. A 1.0-ounce serving of the cereal provides 130 Calories.\n"]], ["block_21", ["reaction described by the following equation:\n"]], ["block_22", ["the reaction:\n"]], ["block_23", ["described in Example 5.6.\n"]], ["block_24", ["of heat absorbed by the reaction that you calculated in a previous exercise.)\n"]], ["block_25", ["produced by combustion of one mole of acetylene in such a torch is likely not equal to the enthalpy of\ncombustion of acetylene listed in Table 5.2. Considering the conditions for which the tabulated data are\nreported, suggest an explanation.\n"]], ["block_26", ["conditions?\n"]], ["block_27", ["per mole of methane under these conditions?\n"]], ["block_28", ["NaOH (density, 1.00 g/mL) are mixed?\n"]], ["block_29", ["If both solutions are at the same temperature and the specific heat of the products is 4.19 J/g \u00b0C, how\nmuch will the temperature increase? What assumption did you make in your calculation?\n"]], ["block_30", ["Assume both the reactants and products are under standard state conditions, and that the heat released is\ndirectly proportional to the enthalpy of combustion of graphite. The temperature of the calorimeter\nincreases from 26.74 \u00b0C to 27.93 \u00b0C. What is the heat capacity of the calorimeter and its contents?\n"]], ["block_31", ["was used in household refrigerators. What mass of SO2 must be evaporated to remove as much heat as\nevaporation of 1.00 kg of CCl2F2 (enthalpy of vaporization is 17.4 kJ/mol)?\nThe vaporization reactions for SO2 and CCl2F2 are\nand\n"]], ["block_32", ["respectively.\n"]], ["block_33", ["amount of heat when cooled from 95.0 to 35.0 \u00b0C, as the heat provided when 100 g of steam is cooled from\n110 \u00b0C to 100 \u00b0C.\n"]], ["block_34", [" 5 \u2022 Exercises \n 251 \n"]]], "page_265": [["block_0", [" 252 \n 5 \u2022 Exercises \n"]], ["block_1", [" 54 . Which of the enthalpies of combustion in Table 5.2 the table are also standard enthalpies of formation?\n 55 . Does the standard enthalpy of formation of H2O(g) differ from \u0394H\u00b0 for the reaction\n"]], ["block_2", [" 56 . Joseph Priestly prepared oxygen in 1774 by heating red mercury(II) oxide with sunlight focused through a\n"]], ["block_3", [" 57 . How many kilojoules of heat will be released when exactly 1 mole of manganese, Mn, is burned to form\n"]], ["block_4", [" 58 . How many kilojoules of heat will be released when exactly 1 mole of iron, Fe, is burned to form Fe2O3(s) at\n"]], ["block_5", [" 59 . The following sequence of reactions occurs in the commercial production of aqueous nitric acid:\n"]], ["block_6", [" 60 . Both graphite and diamond burn.\n"]], ["block_7", [" 61 . From the molar heats of formation in Appendix G, determine how much heat is required to evaporate one\n"]], ["block_8", [" 62 . Which produces more heat?\n"]], ["block_9", [" 63 . Calculate\nfor the process\n"]], ["block_10", [" 64 . Calculate\nfor the process\n"]], ["block_11", [" 65 . Calculate \u0394H for the process\n"]], ["block_12", [" 66 . Calculate\nfor the process\n"]], ["block_13", [" 67 . Calculate the standard molar enthalpy of formation of NO(g) from the following data:\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["lens. How much heat is required to decompose exactly 1 mole of red HgO(s) to Hg(l) and O2(g) under\nstandard conditions?\n"]], ["block_16", ["Mn3O4(s) at standard state conditions?\n"]], ["block_17", ["standard state conditions?\n"]], ["block_18", ["Determine the total energy change for the production of one mole of aqueous nitric acid by this process.\n"]], ["block_19", ["For the conversion of graphite to diamond:\n"]], ["block_20", ["Which produces more heat, the combustion of graphite or the combustion of diamond?\n"]], ["block_21", ["mole of water:\n"]], ["block_22", ["or\n"]], ["block_23", ["for the phase change\n"]], ["block_24", ["from the following information:\n"]], ["block_25", ["from the following information:\n"]], ["block_26", ["from the following information:\n"]], ["block_27", ["from the following information:\n"]]], "page_266": [["block_0", [" 68 . Using the data in Appendix G, calculate the standard enthalpy change for each of the following reactions:\n"]], ["block_1", [" 69 . Using the data in Appendix G, calculate the standard enthalpy change for each of the following reactions:\n"]], ["block_2", [" 70 . The following reactions can be used to prepare samples of metals. Determine the enthalpy change under\n"]], ["block_3", [" 71 . The decomposition of hydrogen peroxide, H2O2, has been used to provide thrust in the control jets of\n"]], ["block_4", [" 72 . Calculate the enthalpy of combustion of propane, C3H8(g), for the formation of H2O(g) and CO2(g). The\n"]], ["block_5", [" 73 . Calculate the enthalpy of combustion of butane, C4H10(g) for the formation of H2O(g) and CO2(g). The\n"]], ["block_6", [" 74 . Both propane and butane are used as gaseous fuels. Which compound produces more heat per gram when\n"]], ["block_7", [" 75 . The white pigment TiO2 is prepared by the reaction of titanium tetrachloride, TiCl4, with water vapor in\n"]], ["block_8", [" 76 . Water gas, a mixture of H2 and CO, is an important industrial fuel produced by the reaction of steam with\n"]], ["block_9", [" 77 . In the early days of automobiles, illumination at night was provided by burning acetylene, C2H2. Though\n"]], ["block_10", [" 78 . From the data in Table 5.2, determine which of the following fuels produces the greatest amount of heat\n"]], ["block_11", [" 79 . The enthalpy of combustion of hard coal averages \u221235 kJ/g, that of gasoline, 1.28\n10kJ/gal. How many\n"]], ["block_12", ["(a)\n(b)\n(c)\n(d)\n"]], ["block_13", ["(a)\n(b)\n(c)\n(d)\n"]], ["block_14", ["standard state conditions for each.\n(a)\n(b)\n(c)\n(d)\n"]], ["block_15", ["various space vehicles. Using the data in Appendix G, determine how much heat is produced by the\ndecomposition of exactly 1 mole of H2O2 under standard conditions.\n"]], ["block_16", ["enthalpy of formation of propane is \u2212104 kJ/mol.\n"]], ["block_17", ["enthalpy of formation of butane is \u2212126 kJ/mol.\n"]], ["block_18", ["burned?\n"]], ["block_19", ["the gas phase:\nHow much heat is evolved in the production of exactly 1 mole of TiO2(s) under standard state conditions?\n"]], ["block_20", ["red hot coke, essentially pure carbon:\n(a) Assuming that coke has the same enthalpy of formation as graphite, calculate\nfor this reaction.\n"]], ["block_21", ["(b) Methanol, a liquid fuel that could possibly replace gasoline, can be prepared from water gas and\nadditional hydrogen at high temperature and pressure in the presence of a suitable catalyst:\n"]], ["block_22", ["Under the conditions of the reaction, methanol forms as a gas. Calculate\nfor this reaction and for the\n"]], ["block_23", ["condensation of gaseous methanol to liquid methanol.\n(c) Calculate the heat of combustion of 1 mole of liquid methanol to H2O(g) and CO2(g).\n"]], ["block_24", ["no longer used as auto headlamps, acetylene is still used as a source of light by some cave explorers. The\nacetylene is (was) prepared in the lamp by the reaction of water with calcium carbide, CaC2:\n"]], ["block_25", ["Calculate the standard enthalpy of the reaction. The\nof CaC2 is \u221215.14 kcal/mol.\n"]], ["block_26", ["per gram when burned under standard conditions: CO(g), CH4(g), or C2H2(g).\n"]], ["block_27", ["kilograms of hard coal provide the same amount of heat as is available from 1.0 gallon of gasoline?\nAssume that the density of gasoline is 0.692 g/mL (the same as the density of isooctane).\n"]], ["block_28", [" 5 \u2022 Exercises \n 253 \n"]]], "page_267": [["block_0", [" 254 \n 5 \u2022 Exercises \n"]], ["block_1", [" 80 . Ethanol, C2H5OH, is used as a fuel for motor vehicles, particularly in Brazil.\n"]], ["block_2", [" 81 . Among the substances that react with oxygen and that have been considered as potential rocket fuels are\n"]], ["block_3", [" 82 . How much heat is produced when 1.25 g of chromium metal reacts with oxygen gas under standard\n"]], ["block_4", [" 83 . Ethylene, C2H4, a byproduct from the fractional distillation of petroleum, is fourth among the 50 chemical\n"]], ["block_5", [" 84 . The oxidation of the sugar glucose, C6H12O6, is described by the following equation:\n"]], ["block_6", [" 85 . Propane, C3H8, is a hydrocarbon that is commonly used as a fuel.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", ["(a) Write the balanced equation for the combustion of ethanol to CO2(g) and H2O(g), and, using the data in\nAppendix G, calculate the enthalpy of combustion of 1 mole of ethanol.\n(b) The density of ethanol is 0.7893 g/mL. Calculate the enthalpy of combustion of exactly 1 L of ethanol.\n(c) Assuming that an automobile\u2019s mileage is directly proportional to the heat of combustion of the fuel,\ncalculate how much farther an automobile could be expected to travel on 1 L of gasoline than on 1 L of\nethanol. Assume that gasoline has the heat of combustion and the density of n\u2013octane, C8H18\n"]], ["block_9", ["diborane [B2H6, produces B2O3(s) and H2O(g)], methane [CH4, produces CO2(g) and H2O(g)], and hydrazine\n[N2H4, produces N2(g) and H2O(g)]. On the basis of the heat released by 1.00 g of each substance in its\nreaction with oxygen, which of these compounds offers the best possibility as a rocket fuel? The\nof\n"]], ["block_10", ["B2H6(g), CH4(g), and N2H4(l) may be found in Appendix G.\n"]], ["block_11", ["conditions?\n"]], ["block_12", ["compounds produced commercially in the largest quantities. About 80% of synthetic ethanol is\nmanufactured from ethylene by its reaction with water in the presence of a suitable catalyst.\n"]], ["block_13", ["Using the data in the table in Appendix G, calculate \u0394H\u00b0 for the reaction.\n"]], ["block_14", ["The metabolism of glucose gives the same products, although the glucose reacts with oxygen in a series of\nsteps in the body.\n(a) How much heat in kilojoules can be produced by the metabolism of 1.0 g of glucose?\n(b) How many Calories can be produced by the metabolism of 1.0 g of glucose?\n"]], ["block_15", ["(a) Write a balanced equation for the complete combustion of propane gas.\n(b) Calculate the volume of air at 25 \u00b0C and 1.00 atmosphere that is needed to completely combust 25.0\ngrams of propane. Assume that air is 21.0 percent O2 by volume. (Hint: We will see how to do this\ncalculation in a later chapter on gases\u2014for now use the information that 1.00 L of air at 25 \u00b0C and 1.00 atm\ncontains 0.275 g of O2.)\n(c) The heat of combustion of propane is \u22122,219.2 kJ/mol. Calculate the heat of formation,\nof propane\n"]], ["block_16", ["given that\nof H2O(l) = \u2212285.8 kJ/mol and\nof CO2(g) = \u2212393.5 kJ/mol.\n"]], ["block_17", ["(d) Assuming that all of the heat released in burning 25.0 grams of propane is transferred to 4.00\nkilograms of water, calculate the increase in temperature of the water.\n"]], ["block_18", ["density = 0.7025 g/mL).\n"]]], "page_268": [["block_0", [" 86 . During a recent winter month in Sheboygan, Wisconsin, it was necessary to obtain 3500 kWh of heat\n"]], ["block_1", ["provided by a natural gas furnace with 89% efficiency to keep a small house warm (the efficiency of a gas\nfurnace is the percent of the heat produced by combustion that is transferred into the house).\n(a) Assume that natural gas is pure methane and determine the volume of natural gas in cubic feet that\nwas required to heat the house. The average temperature of the natural gas was 56 \u00b0F; at this temperature\nand a pressure of 1 atm, natural gas has a density of 0.681 g/L.\n(b) How many gallons of LPG (liquefied petroleum gas) would be required to replace the natural gas used?\nAssume the LPG is liquid propane [C3H8: density, 0.5318 g/mL; enthalpy of combustion, 2219 kJ/mol for\nthe formation of CO2(g) and H2O(l)] and the furnace used to burn the LPG has the same efficiency as the\ngas furnace.\n(c) What mass of carbon dioxide is produced by combustion of the methane used to heat the house?\n(d) What mass of water is produced by combustion of the methane used to heat the house?\n(e) What volume of air is required to provide the oxygen for the combustion of the methane used to heat\nthe house? Air contains 23% oxygen by mass. The average density of air during the month was 1.22 g/L.\n(f) How many kilowatt\u2013hours (1 kWh = 3.6\n10J) of electricity would be required to provide the heat\n"]], ["block_2", ["necessary to heat the house? Note electricity is 100% efficient in producing heat inside a house.\n(g) Although electricity is 100% efficient in producing heat inside a house, production and distribution of\nelectricity is not 100% efficient. The efficiency of production and distribution of electricity produced in a\ncoal-fired power plant is about 40%. A certain type of coal provides 2.26 kWh per pound upon\ncombustion. What mass of this coal in kilograms will be required to produce the electrical energy\nnecessary to heat the house if the efficiency of generation and distribution is 40%?\n"]], ["block_3", [" 5 \u2022 Exercises \n 255 \n"]]], "page_269": [["block_0", [" 256 \n 5 \u2022 Exercises \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_270": [["block_0", [{"image_0": "270_0.png", "coords": [36, 131, 622, 424]}]], ["block_1", ["CHAPTER 6\nElectronic Structure and Periodic\nProperties of Elements\n"]], ["block_2", [" Figure 6.1 \nThe Crab Nebula consists of remnants of a supernova (the explosion of a star). NASA\u2019s Hubble Space\n"]], ["block_3", ["Telescope produced this composite image. Measurements of the emitted light wavelengths enabled astronomers to\nidentify the elements in the nebula, determining that it contains specific ions including S(green filaments) and O\n"]], ["block_4", ["(red filaments). (credit: modification of work by NASA and ESA)\n"]], ["block_5", [" CHAPTER OUTLINE \n"]], ["block_6", [" 6.1 Electromagnetic Energy \n 6.2 The Bohr Model \n 6.3 Development of Quantum Theory \n 6.4 Electronic Structure of Atoms (Electron Configurations) \n 6.5 Periodic Variations in Element Properties \n"]], ["block_7", [" INTRODUCTION \n"]], ["block_8", ["even during the day, which then disappeared slowly over the next two years. The sudden appearance was due\nto a supernova explosion, which was much brighter than the original star. Even though this supernova was\nobserved almost a millennium ago, the remaining Crab Nebula (Figure 6.1) continues to release energy today.\nIt emits not only visible light but also infrared light, X-rays, and other forms of electromagnetic radiation. The\nnebula emits both continuous spectra (the blue-white glow) and atomic emission spectra (the colored\nfilaments). In this chapter, we will discuss light and other forms of electromagnetic radiation and how they are\nrelated to the electronic structure of atoms. We will also see how this radiation can be used to identify\n"]], ["block_9", ["In 1054, Chinese astronomers recorded the appearance of a \u201cguest star\u201d in the sky, visible\n"]]], "page_271": [["block_0", [" 258 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", ["elements, even from thousands of light years away.\n"]], ["block_2", [" 6.1 Electromagnetic Energy \n"]], ["block_3", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_4", ["The nature of light has been a subject of inquiry since antiquity. In the seventeenth century, Isaac Newton\nperformed experiments with lenses and prisms and was able to demonstrate that white light consists of the\nindividual colors of the rainbow combined together. Newton explained his optics findings in terms of a\n\"corpuscular\" view of light, in which light was composed of streams of extremely tiny particles travelling at\nhigh speeds according to Newton's laws of motion. Others in the seventeenth century, such as Christiaan\nHuygens, had shown that optical phenomena such as reflection and refraction could be equally well explained\nin terms of light as waves travelling at high speed through a medium called \"luminiferous aether\" that was\nthought to permeate all space. Early in the nineteenth century, Thomas Young demonstrated that light passing\nthrough narrow, closely spaced slits produced interference patterns that could not be explained in terms of\nNewtonian particles but could be easily explained in terms of waves. Later in the nineteenth century, after\nJames Clerk Maxwell developed his theory of electromagnetic radiation and showed that light was the visible\npart of a vast spectrum of electromagnetic waves, the particle view of light became thoroughly discredited. By\nthe end of the nineteenth century, scientists viewed the physical universe as roughly comprising two separate\ndomains: matter composed of particles moving according to Newton's laws of motion, and electromagnetic\nradiation consisting of waves governed by Maxwell's equations. Today, these domains are referred to as\nclassical mechanics and classical electrodynamics (or classical electromagnetism). Although there were a few\nphysical phenomena that could not be explained within this framework, scientists at that time were so\nconfident of the overall soundness of this framework that they viewed these aberrations as puzzling paradoxes\nthat would ultimately be resolved somehow within this framework. As we shall see, these paradoxes led to a\ncontemporary framework that intimately connects particles and waves at a fundamental level called wave-\nparticle duality, which has superseded the classical view.\n"]], ["block_5", ["Visible light and other forms of electromagnetic radiation play important roles in chemistry, since they can be\nused to infer the energies of electrons within atoms and molecules. Much of modern technology is based on\nelectromagnetic radiation. For example, radio waves from a mobile phone, X-rays used by dentists, the energy\nused to cook food in your microwave, the radiant heat from red-hot objects, and the light from your television\nscreen are forms of electromagnetic radiation that all exhibit wavelike behavior.\n"]], ["block_6", [" Waves \n"]], ["block_7", ["A wave is an oscillation or periodic movement that can transport energy from one point in space to another.\nCommon examples of waves are all around us. Shaking the end of a rope transfers energy from your hand to\nthe other end of the rope, dropping a pebble into a pond causes waves to ripple outward along the water's\nsurface, and the expansion of air that accompanies a lightning strike generates sound waves (thunder) that can\ntravel outward for several miles. In each of these cases, kinetic energy is transferred through matter (the rope,\nwater, or air) while the matter remains essentially in place. An insightful example of a wave occurs in sports\nstadiums when fans in a narrow region of seats rise simultaneously and stand with their arms raised up for a\nfew seconds before sitting down again while the fans in neighboring sections likewise stand up and sit down in\nsequence. While this wave can quickly encircle a large stadium in a few seconds, none of the fans actually\ntravel with the wave-they all stay in or above their seats.\n"]], ["block_8", ["Waves need not be restricted to travel through matter. As Maxwell showed, electromagnetic waves consist of an\nelectric field oscillating in step with a perpendicular magnetic field, both of which are perpendicular to the\ndirection of travel. These waves can travel through a vacuum at a constant speed of 2.998\n10m/s, the speed\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["\u2022\nExplain the basic behavior of waves, including travelling waves and standing waves\n"]], ["block_11", ["\u2022\nDescribe the wave nature of light\n"]], ["block_12", ["\u2022\nUse appropriate equations to calculate related light-wave properties such as frequency, wavelength, and energy\n"]], ["block_13", ["\u2022\nDistinguish between line and continuous emission spectra\n"]], ["block_14", ["\u2022\nDescribe the particle nature of light\n"]]], "page_272": [["block_0", ["of light (denoted by c).\n"]], ["block_1", ["All waves, including forms of electromagnetic radiation, are characterized by, a wavelength (denoted by \u03bb, the\nlowercase Greek letter lambda), a frequency (denoted by \u03bd, the lowercase Greek letter nu), and an amplitude .\nAs can be seen in Figure 6.2, the wavelength is the distance between two consecutive peaks or troughs in a\nwave (measured in meters in the SI system). Electromagnetic waves have wavelengths that fall within an\nenormous range-wavelengths of kilometers (10m) to picometers (10m) have been observed. The\nfrequency is the number of wave cycles that pass a specified point in space in a specified amount of time (in\nthe SI system, this is measured in seconds). A cycle corresponds to one complete wavelength. The unit for\nfrequency, expressed as cycles per second [s], is the hertz (Hz) . Common multiples of this unit are\nmegahertz, (1 MHz = 1\n10Hz) and gigahertz (1 GHz = 1\n10Hz). The amplitude corresponds to the\n"]], ["block_2", ["magnitude of the wave's displacement and so, in Figure 6.2, this corresponds to one-half the height between\nthe peaks and troughs. The amplitude is related to the intensity of the wave, which for light is the brightness,\nand for sound is the loudness.\n"]], ["block_3", [{"image_0": "272_0.png", "coords": [72, 234, 540, 461]}]], ["block_4", [" FIGURE 6.2 \nOne-dimensional sinusoidal waves show the relationship among wavelength, frequency, and speed.\n"]], ["block_5", ["The wave with the shortest wavelength has the highest frequency. Amplitude is one-half the height of the wave from\npeak to trough.\n"]], ["block_6", ["The product of a wave's wavelength (\u03bb) and its frequency (\u03bd), \u03bb\u03bd, is the speed of the wave. Thus, for\nelectromagnetic radiation in a vacuum, speed is equal to the fundamental constant, c:\n"]], ["block_7", ["Wavelength and frequency are inversely proportional: As the wavelength increases, the frequency decreases.\nThe inverse proportionality is illustrated in Figure 6.3. This figure also shows the electromagnetic spectrum ,\nthe range of all types of electromagnetic radiation. Each of the various colors of visible light has specific\nfrequencies and wavelengths associated with them, and you can see that visible light makes up only a small\nportion of the electromagnetic spectrum. Because the technologies developed to work in various parts of the\nelectromagnetic spectrum are different, for reasons of convenience and historical legacies, different units are\ntypically used for different parts of the spectrum. For example, radio waves are usually specified as\nfrequencies (typically in units of MHz), while the visible region is usually specified in wavelengths (typically in\nunits of nm or angstroms).\n"]], ["block_8", [" 6.1 \u2022 Electromagnetic Energy \n 259 \n"]]], "page_273": [["block_0", [" 260 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", [" FIGURE 6.3 \nPortions of the electromagnetic spectrum are shown in order of decreasing frequency and increasing\n"]], ["block_2", ["wavelength. (credit \u201cCosmic ray\": modification of work by NASA; credit \u201cPET scan\": modification of work by the\nNational Institute of Health; credit \u201cX-ray\": modification of work by Dr. Jochen Lengerke; credit \u201cDental curing\":\nmodification of work by the Department of the Navy; credit \u201cNight vision\": modification of work by the Department\nof the Army; credit \u201cRemote\": modification of work by Emilian Robert Vicol; credit \u201cCell phone\": modification of work\nby Brett Jordan; credit \u201cMicrowave oven\": modification of work by Billy Mabray; credit \u201cUltrasound\": modification of\nwork by Jane Whitney; credit \u201cAM radio\": modification of work by Dave Clausen)\n"]], ["block_3", [" Determining the Frequency and Wavelength of Radiation \n"]], ["block_4", ["A sodium streetlight gives off yellow light that has a wavelength of 589 nm (1 nm = 1\n10m). What is the\n"]], ["block_5", ["frequency of this light?\n"]], ["block_6", [" Solution \n"]], ["block_7", ["We can rearrange the equation c = \u03bb\u03bd to solve for the frequency:\n"]], ["block_8", ["Since c is expressed in meters per second, we must also convert 589 nm to meters.\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["One of the frequencies used to transmit and receive cellular telephone signals in the United States is 850 MHz.\nWhat is the wavelength in meters of these radio waves?\n"]], ["block_11", [" Answer: \n0.353 m = 35.3 cm\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", [{"image_0": "273_0.png", "coords": [74, 57, 537, 356]}]], ["block_14", ["EXAMPLE 6.1\n"]]], "page_274": [["block_0", ["Chemistry in Everyday Life\n"]], ["block_1", [" Wireless Communication \n"]], ["block_2", [" FIGURE 6.4 \nRadio and cell towers are typically used to transmit long-wavelength electromagnetic radiation.\n"]], ["block_3", ["Increasingly, cell towers are designed to blend in with the landscape, as with the Tucson, Arizona, cell tower\n(right) disguised as a palm tree. (credit left: modification of work by Sir Mildred Pierce; credit middle:\nmodification of work by M.O. Stevens)\n"]], ["block_4", ["Many valuable technologies operate in the radio (3 kHz-300 GHz) frequency region of the electromagnetic\nspectrum. At the low frequency (low energy, long wavelength) end of this region are AM (amplitude\nmodulation) radio signals (540-2830 kHz) that can travel long distances. FM (frequency modulation) radio\nsignals are used at higher frequencies (87.5-108.0 MHz). In AM radio, the information is transmitted by\nvarying the amplitude of the wave (Figure 6.5). In FM radio, by contrast, the amplitude is constant and the\ninstantaneous frequency varies.\n"]], ["block_5", [" FIGURE 6.5 \nThis schematic depicts how amplitude modulation (AM) and frequency modulation (FM) can be\n"]], ["block_6", ["used to transmit a radio wave.\n"]], ["block_7", [{"image_0": "274_0.png", "coords": [90, 105, 522, 295]}]], ["block_8", [{"image_1": "274_1.png", "coords": [153, 437, 458, 682]}]], ["block_9", [" 6.1 \u2022 Electromagnetic Energy \n 261 \n"]]], "page_275": [["block_0", [" 262 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", ["One particularly characteristic phenomenon of waves results when two or more waves come into contact: They\ninterfere with each other. Figure 6.6 shows the interference patterns that arise when light passes through\nnarrow slits closely spaced about a wavelength apart. The fringe patterns produced depend on the wavelength,\nwith the fringes being more closely spaced for shorter wavelength light passing through a given set of slits.\nWhen the light passes through the two slits, each slit effectively acts as a new source, resulting in two closely\nspaced waves coming into contact at the detector (the camera in this case). The dark regions in Figure 6.6\ncorrespond to regions where the peaks for the wave from one slit happen to coincide with the troughs for the\nwave from the other slit (destructive interference), while the brightest regions correspond to the regions where\nthe peaks for the two waves (or their two troughs) happen to coincide (constructive interference). Likewise,\nwhen two stones are tossed close together into a pond, interference patterns are visible in the interactions\nbetween the waves produced by the stones. Such interference patterns cannot be explained by particles\nmoving according to the laws of classical mechanics.\n"]], ["block_2", [" FIGURE 6.6 \nInterference fringe patterns are shown for light passing through two closely spaced, narrow slits. The\n"]], ["block_3", ["spacing of the fringes depends on the wavelength, with the fringes being more closely spaced for the shorter-\nwavelength blue light. (credit: PASCO)\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", ["Other technologies also operate in the radio-wave portion of the electromagnetic spectrum. For example,\n4G cellular telephone signals are approximately 880 MHz, while Global Positioning System (GPS) signals\noperate at 1.228 and 1.575 GHz, local area wireless technology (Wi-Fi) networks operate at 2.4 to 5 GHz,\nand highway toll sensors operate at 5.8 GHz. The frequencies associated with these applications are\nconvenient because such waves tend not to be absorbed much by common building materials.\n"]], ["block_6", ["Portrait of a Chemist\n"]], ["block_7", [" Dorothy Crowfoot Hodgkin \nX-rays exhibit wavelengths of approximately 0.01\u201310 nm. Since these wavelengths are comparable to the\nspaces between atoms in a crystalline solid, X-rays are scattered when they pass through crystals. The\nscattered rays undergo constructive and destructive interference that creates a specific diffraction pattern\nthat may be measured and used to precisely determine the positions of atoms within the crystal. This\nphenomenon of X-ray diffraction is the basis for very powerful techniques enabling the determination of\nmolecular structure. One of the pioneers who applied this powerful technology to important biochemical\nsubstances was Dorothy Crowfoot Hodgkin .\n"]], ["block_8", ["Born in Cairo, Egypt, in 1910 to British parents, Dorothy\u2019s fascination with chemistry was fostered early in\nher life. At age 11 she was enrolled in a prestigious English grammar school where she was one of just two\ngirls allowed to study chemistry. On her 16th birthday, her mother, Molly, gifted her a book on X-ray\ncrystallography, which had a profound impact on the trajectory of her career. She studied chemistry at\nOxford University, graduating with first-class honors in 1932 and directly entering Cambridge University to\npursue a doctoral degree. At Cambridge, Dorothy recognized the promise of X-ray crystallography for\nprotein structure determinations, conducting research that earned her a PhD in 1937. Over the course of a\nvery productive career, Dr. Hodgkin was credited with determining structures for several important\nbiomolecules, including cholesterol iodide, penicillin, and vitamin B12. In recognition of her achievements\nin the use of X-ray techniques to elucidate the structures of biochemical substances, she was awarded the\n1964 Nobel Prize in Chemistry. In 1969, she led a team of scientists who deduced the structure of insulin,\nfacilitating the mass production of this hormone and greatly advancing the treatment of diabetic patients\nworldwide. Dr. Hodgkin continued working with the international scientific community, earning numerous\ndistinctions and awards prior to her death in 1993.\n"]], ["block_9", [{"image_0": "275_0.png", "coords": [189, 304, 423, 350]}]]], "page_276": [["block_0", ["Not all waves are travelling waves. Standing waves (also known as stationary waves ) remain constrained\nwithin some region of space. As we shall see, standing waves play an important role in our understanding of\nthe electronic structure of atoms and molecules. The simplest example of a standing wave is a one-\ndimensional wave associated with a vibrating string that is held fixed at its two end points. Figure 6.7 shows\nthe four lowest-energy standing waves (the fundamental wave and the lowest three harmonics) for a vibrating\nstring at a particular amplitude. Although the string's motion lies mostly within a plane, the wave itself is\nconsidered to be one dimensional, since it lies along the length of the string. The motion of string segments in\na direction perpendicular to the string length generates the waves and so the amplitude of the waves is visible\nas the maximum displacement of the curves seen in Figure 6.7. The key observation from the figure is that\nonly those waves having an integer number, n, of half-wavelengths between the end points can form. A system\nwith fixed end points such as this restricts the number and type of the possible waveforms. This is an example\nof quantization , in which only discrete values from a more general set of continuous values of some property\nare observed. Another important observation is that the harmonic waves (those waves displaying more than\none-half wavelength) all have one or more points between the two end points that are not in motion. These\nspecial points are nodes . The energies of the standing waves with a given amplitude in a vibrating string\nincrease with the number of half-wavelengths n. Since the number of nodes is n \u2013 1, the energy can also be\nsaid to depend on the number of nodes, generally increasing as the number of nodes increases.\n"]], ["block_1", [" FIGURE 6.7 \nA vibrating string shows some one-dimensional standing waves. Since the two end points of the string\n"]], ["block_2", ["are held fixed, only waves having an integer number of half-wavelengths can form. The points on the string between\nthe end points that are not moving are called the nodes.\n"]], ["block_3", ["An example of two-dimensional standing waves is shown in Figure 6.8, which shows the vibrational patterns\non a flat surface. Although the vibrational amplitudes cannot be seen like they could in the vibrating string, the\nnodes have been made visible by sprinkling the drum surface with a powder that collects on the areas of the\nsurface that have minimal displacement. For one-dimensional standing waves, the nodes were points on the\nline, but for two-dimensional standing waves, the nodes are lines on the surface (for three-dimensional\nstanding waves, the nodes are two-dimensional surfaces within the three-dimensional volume).\n"]], ["block_4", [" FIGURE 6.8 \nTwo-dimensional standing waves can be visualized on a vibrating surface. The surface has been\n"]], ["block_5", ["sprinkled with a powder that collects near the nodal lines. There are two types of nodes visible: radial nodes\n"]], ["block_6", [{"image_0": "276_0.png", "coords": [180, 278, 432, 401]}]], ["block_7", [{"image_1": "276_1.png", "coords": [180, 530, 432, 702]}]], ["block_8", [" 6.1 \u2022 Electromagnetic Energy \n 263 \n"]]], "page_277": [["block_0", [" 264 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", ["(circles) and angular nodes (radii).\n"]], ["block_2", ["You can watch the formation of various radial nodes here (http://openstax.org/l/16radnodes) as singer Imogen\nHeap projects her voice across a kettle drum.\n"]], ["block_3", [" Blackbody Radiation and the Ultraviolet Catastrophe \n"]], ["block_4", ["The last few decades of the nineteenth century witnessed intense research activity in commercializing newly\ndiscovered electric lighting. This required obtaining a better understanding of the distributions of light\nemitted from various sources being considered. Artificial lighting is usually designed to mimic natural\nsunlight within the limitations of the underlying technology. Such lighting consists of a range of broadly\ndistributed frequencies that form a continuous spectrum . Figure 6.9 shows the wavelength distribution for\nsunlight. The most intense radiation is in the visible region, with the intensity dropping off rapidly for shorter\nwavelength ultraviolet (UV) light, and more slowly for longer wavelength infrared (IR) light.\n"]], ["block_5", [{"image_0": "277_0.png", "coords": [72, 256, 540, 562]}]], ["block_6", [" FIGURE 6.9 \nThe spectral distribution (light intensity vs. wavelength) of sunlight reaches the Earth's atmosphere as\n"]], ["block_7", ["UV light, visible light, and IR light. The unabsorbed sunlight at the top of the atmosphere has a distribution that\napproximately matches the theoretical distribution of a blackbody at 5250 \u00b0C, represented by the blue curve.\n(credit: modification of work by American Society for Testing and Materials (ASTM) Terrestrial Reference Spectra for\nPhotovoltaic Performance Evaluation)\n"]], ["block_8", ["In Figure 6.9, the solar distribution is compared to a representative distribution, called a blackbody spectrum,\nthat corresponds to a temperature of 5250 \u00b0C. The blackbody spectrum matches the solar spectrum quite well.\nA blackbody is a convenient, ideal emitter that approximates the behavior of many materials when heated. It\nis \u201cideal\u201d in the same sense that an ideal gas is a convenient, simple representation of real gases that works\nwell, provided that the pressure is not too high nor the temperature too low. A good approximation of a\nblackbody that can be used to observe blackbody radiation is a metal oven that can be heated to very high\ntemperatures. The oven has a small hole allowing for the light being emitted within the oven to be observed\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["LINK TO LEARNING\n"]]], "page_278": [["block_0", ["with a spectrometer so that the wavelengths and their intensities can be measured. Figure 6.10 shows the\nresulting curves for some representative temperatures. Each distribution depends only on a single parameter:\nthe temperature. The maxima in the blackbody curves, \u03bbmax, shift to shorter wavelengths as the temperature\nincreases, reflecting the observation that metals being heated to high temperatures begin to glow a darker red\nthat becomes brighter as the temperature increases, eventually becoming white hot at very high temperatures\nas the intensities of all of the visible wavelengths become appreciable. This common observation was at the\nheart of the first paradox that showed the fundamental limitations of classical physics that we will examine.\n"]], ["block_1", ["Physicists derived mathematical expressions for the blackbody curves using well-accepted concepts from the\ntheories of classical mechanics and classical electromagnetism. The theoretical expressions as functions of\ntemperature fit the observed experimental blackbody curves well at longer wavelengths, but showed\nsignificant discrepancies at shorter wavelengths. Not only did the theoretical curves not show a peak, they\nabsurdly showed the intensity becoming infinitely large as the wavelength became smaller, which would imply\nthat everyday objects at room temperature should be emitting large amounts of UV light. This became known\nas the \u201cultraviolet catastrophe\u201d because no one could find any problems with the theoretical treatment that\ncould lead to such unrealistic short-wavelength behavior. Finally, around 1900, Max Planck derived a\ntheoretical expression for blackbody radiation that fit the experimental observations exactly (within\nexperimental error). Planck developed his theoretical treatment by extending the earlier work that had been\nbased on the premise that the atoms composing the oven vibrated at increasing frequencies (or decreasing\nwavelengths) as the temperature increased, with these vibrations being the source of the emitted\nelectromagnetic radiation. But where the earlier treatments had allowed the vibrating atoms to have any\nenergy values obtained from a continuous set of energies (perfectly reasonable, according to classical physics),\nPlanck found that by restricting the vibrational energies to discrete values for each frequency, he could derive\nan expression for blackbody radiation that correctly had the intensity dropping rapidly for the short\nwavelengths in the UV region.\n"]], ["block_2", ["The quantity h is a constant now known as Planck's constant, in his honor. Although Planck was pleased he\nhad resolved the blackbody radiation paradox, he was disturbed that to do so, he needed to assume the\nvibrating atoms required quantized energies, which he was unable to explain. The value of Planck's constant is\nvery small, 6.626\n10joule seconds (J s), which helps explain why energy quantization had not been\n"]], ["block_3", ["observed previously in macroscopic phenomena.\n"]], ["block_4", [{"image_0": "278_0.png", "coords": [91, 457, 520, 709]}]], ["block_5", [" FIGURE 6.10 \nBlackbody spectral distribution curves are shown for some representative temperatures.\n"]], ["block_6", [" 6.1 \u2022 Electromagnetic Energy \n 265 \n"]]], "page_279": [["block_0", [" 266 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", [" The Photoelectric Effect \n"]], ["block_2", ["The next paradox in the classical theory to be resolved concerned the photoelectric effect (Figure 6.11). It had\nbeen observed that electrons could be ejected from the clean surface of a metal when light having a frequency\ngreater than some threshold frequency was shone on it. Surprisingly, the kinetic energy of the ejected\nelectrons did not depend on the brightness of the light, but increased with increasing frequency of the light.\nSince the electrons in the metal had a certain amount of binding energy keeping them there, the incident light\nneeded to have more energy to free the electrons. According to classical wave theory, a wave's energy depends\non its intensity (which depends on its amplitude), not its frequency. One part of these observations was that the\nnumber of electrons ejected within in a given time period was seen to increase as the brightness increased. In\n1905, Albert Einstein was able to resolve the paradox by incorporating Planck's quantization findings into the\ndiscredited particle view of light (Einstein actually won his Nobel prize for this work, and not for his theories of\nrelativity for which he is most famous).\n"]], ["block_3", ["Einstein argued that the quantized energies that Planck had postulated in his treatment of blackbody radiation\ncould be applied to the light in the photoelectric effect so that the light striking the metal surface should not be\nviewed as a wave, but instead as a stream of particles (later called photons ) whose energy depended on their\nfrequency, according to Planck's formula, E = h\u03bd (or, in terms of wavelength using c = \u03bd\u03bb,\n). Electrons\n"]], ["block_4", ["were ejected when hit by photons having sufficient energy (a frequency greater than the threshold). The\ngreater the frequency, the greater the kinetic energy imparted to the escaping electrons by the collisions.\nEinstein also argued that the light intensity did not depend on the amplitude of the incoming wave, but instead\ncorresponded to the number of photons striking the surface within a given time period. This explains why the\nnumber of ejected electrons increased with increasing brightness, since the greater the number of incoming\nphotons, the greater the likelihood that they would collide with some of the electrons.\n"]], ["block_5", ["With Einstein's findings, the nature of light took on a new air of mystery. Although many light phenomena\ncould be explained either in terms of waves or particles, certain phenomena, such as the interference patterns\nobtained when light passed through a double slit, were completely contrary to a particle view of light, while\nother phenomena, such as the photoelectric effect, were completely contrary to a wave view of light. Somehow,\nat a deep fundamental level still not fully understood, light is both wavelike and particle-like. This is known as\n wave-particle duality .\n"]], ["block_6", [" FIGURE 6.11 \nPhotons with low frequencies do not have enough energy to cause electrons to be ejected via the\n"]], ["block_7", ["photoelectric effect. For any frequency of light above the threshold frequency, the kinetic energy of an ejected\nelectron will increase linearly with the energy of the incoming photon.\n"]], ["block_8", [" Calculating the Energy of Radiation \n"]], ["block_9", ["When we see light from a neon sign, we are observing radiation from excited neon atoms. If this radiation has a\nwavelength of 640 nm, what is the energy of the photon being emitted?\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [{"image_0": "279_0.png", "coords": [73, 438, 538, 577]}]], ["block_12", ["EXAMPLE 6.2\n"]]], "page_280": [["block_0", [" Solution \n"]], ["block_1", ["We use the part of Planck's equation that includes the wavelength, \u03bb, and convert units of nanometers to\nmeters so that the units of \u03bb and c are the same.\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["The microwaves in an oven are of a specific frequency that will heat the water molecules contained in food.\n(This is why most plastics and glass do not become hot in a microwave oven-they do not contain water\nmolecules.) This frequency is about 3\n10Hz. What is the energy of one photon in these microwaves?\n"]], ["block_4", [" Answer: \n2\n10J\n"]], ["block_5", ["Use this simulation program (http://openstax.org/l/16photelec) to experiment with the photoelectric effect to\nsee how intensity, frequency, type of metal, and other factors influence the ejected photons.\n"]], ["block_6", [" Photoelectric Effect \n"]], ["block_7", ["Identify which of the following statements are false and, where necessary, change the italicized word or phrase\nto make them true, consistent with Einstein's explanation of the photoelectric effect.\n"]], ["block_8", ["(a) Increasing the brightness of incoming light increases the kinetic energy of the ejected electrons.\n"]], ["block_9", ["(b) Increasing the wavelength of incoming light increases the kinetic energy of the ejected electrons.\n"]], ["block_10", ["(c) Increasing the brightness of incoming light increases the number of ejected electrons.\n"]], ["block_11", ["(d) Increasing the frequency of incoming light can increase the number of ejected electrons.\n"]], ["block_12", [" Solution \n"]], ["block_13", ["(a) False. Increasing the brightness of incoming light has no effect on the kinetic energy of the ejected\nelectrons. Only energy, not the number or amplitude, of the photons influences the kinetic energy of the\nelectrons.\n"]], ["block_14", ["(b) False. Increasing the frequency of incoming light increases the kinetic energy of the ejected electrons.\nFrequency is proportional to energy and inversely proportional to wavelength. Frequencies above the\nthreshold value transfer the excess energy into the kinetic energy of the electrons.\n"]], ["block_15", ["(c) True. Because the number of collisions with photons increases with brighter light, the number of ejected\nelectrons increases.\n"]], ["block_16", ["(d) True with regard to the threshold energy binding the electrons to the metal. Below this threshold, electrons\nare not emitted and above it they are. Once over the threshold value, further increasing the frequency does not\nincrease the number of ejected electrons\n"]], ["block_17", ["LINK TO LEARNING\n"]], ["block_18", ["EXAMPLE 6.3\n"]], ["block_19", [" 6.1 \u2022 Electromagnetic Energy \n 267 \n"]]], "page_281": [["block_0", [" 268 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["Calculate the threshold energy in kJ/mol of electrons in aluminum, given that the lowest frequency photon for\nwhich the photoelectric effect is observed is 9.87\n10Hz.\n"]], ["block_3", [" Answer: \n394 kJ/mol\n"]], ["block_4", [" Line Spectra \n"]], ["block_5", ["Another paradox within the classical electromagnetic theory that scientists in the late nineteenth century\nstruggled with concerned the light emitted from atoms and molecules. When solids, liquids, or condensed\ngases are heated sufficiently, they radiate some of the excess energy as light. Photons produced in this manner\nhave a range of energies, and thereby produce a continuous spectrum in which an unbroken series of\nwavelengths is present. Most of the light generated from stars (including our sun) is produced in this fashion.\nYou can see all the visible wavelengths of light present in sunlight by using a prism to separate them. As can be\nseen in Figure 6.9, sunlight also contains UV light (shorter wavelengths) and IR light (longer wavelengths) that\ncan be detected using instruments but that are invisible to the human eye. Incandescent (glowing) solids such\nas tungsten filaments in incandescent lights also give off light that contains all wavelengths of visible light.\nThese continuous spectra can often be approximated by blackbody radiation curves at some appropriate\ntemperature, such as those shown in Figure 6.10.\n"]], ["block_6", ["In contrast to continuous spectra, light can also occur as discrete or line spectra having very narrow line\nwidths interspersed throughout the spectral regions such as those shown in Figure 6.13. Exciting a gas at low\npartial pressure using an electrical current, or heating it, will produce line spectra. Fluorescent light bulbs and\nneon signs operate in this way (Figure 6.12). Each element displays its own characteristic set of lines, as do\nmolecules, although their spectra are generally much more complicated.\n"]], ["block_7", [" FIGURE 6.12 \nNeon signs operate by exciting a gas at low partial pressure using an electrical current. This sign\n"]], ["block_8", ["shows the elaborate artistic effects that can be achieved. (credit: Dave Shaver)\n"]], ["block_9", ["Each emission line consists of a single wavelength of light, which implies that the light emitted by a gas\nconsists of a set of discrete energies. For example, when an electric discharge passes through a tube\ncontaining hydrogen gas at low pressure, the H2 molecules are broken apart into separate H atoms and we see\na blue-pink color. Passing the light through a prism produces a line spectrum, indicating that this light is\ncomposed of photons of four visible wavelengths, as shown in Figure 6.13.\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [{"image_0": "281_0.png", "coords": [189, 386, 423, 555]}]]], "page_282": [["block_0", [" FIGURE 6.13 \nCompare the two types of emission spectra: continuous spectrum of white light (top) and the line\n"]], ["block_1", ["spectra of the light from excited sodium, hydrogen, calcium, and mercury atoms.\n"]], ["block_2", ["The origin of discrete spectra in atoms and molecules was extremely puzzling to scientists in the late\nnineteenth century, since according to classical electromagnetic theory, only continuous spectra should be\nobserved. Even more puzzling, in 1885, Johann Balmer was able to derive an empirical equation that related\nthe four visible wavelengths of light emitted by hydrogen atoms to whole integers. That equation is the\nfollowing one, in which k is a constant:\n"]], ["block_3", ["Other discrete lines for the hydrogen atom were found in the UV and IR regions. Johannes Rydberg generalized\nBalmer's work and developed an empirical formula that predicted all of hydrogen's emission lines, not just\nthose restricted to the visible range, where, n1 and n2 are integers, n1 < n2, and\n\u221e \n"]], ["block_4", ["(1.097\n10m).\n"]], ["block_5", ["Even in the late nineteenth century, spectroscopy was a very precise science, and so the wavelengths of\nhydrogen were measured to very high accuracy, which implied that the Rydberg constant could be determined\nvery precisely as well. That such a simple formula as the Rydberg formula could account for such precise\nmeasurements seemed astounding at the time, but it was the eventual explanation for emission spectra by\nNeils Bohr in 1913 that ultimately convinced scientists to abandon classical physics and spurred the\ndevelopment of modern quantum mechanics.\n"]], ["block_6", [{"image_0": "282_0.png", "coords": [82, 57, 529, 365]}]], ["block_7", ["\u221e\n"]], ["block_8", [" 6.1 \u2022 Electromagnetic Energy \n 269 \n"]]], "page_283": [["block_0", [" 270 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", [" 6.2 The Bohr Model \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["Following the work of Ernest Rutherford and his colleagues in the early twentieth century, the picture of atoms\nconsisting of tiny dense nuclei surrounded by lighter and even tinier electrons continually moving about the\nnucleus was well established. This picture was called the planetary model, since it pictured the atom as a\nminiature \u201csolar system\u201d with the electrons orbiting the nucleus like planets orbiting the sun. The simplest\natom is hydrogen, consisting of a single proton as the nucleus about which a single electron moves. The\nelectrostatic force attracting the electron to the proton depends only on the distance between the two particles.\nThis classical mechanics description of the atom is incomplete, however, since an electron moving in an\nelliptical orbit would be accelerating (by changing direction) and, according to classical electromagnetism, it\nshould continuously emit electromagnetic radiation. This loss in orbital energy should result in the electron\u2019s\norbit getting continually smaller until it spirals into the nucleus, implying that atoms are inherently unstable.\n"]], ["block_4", ["In 1913, Niels Bohr attempted to resolve the atomic paradox by ignoring classical electromagnetism\u2019s\nprediction that the orbiting electron in hydrogen would continuously emit light. Instead, he incorporated into\nthe classical mechanics description of the atom Planck\u2019s ideas of quantization and Einstein\u2019s finding that light\nconsists of photons whose energy is proportional to their frequency. Bohr assumed that the electron orbiting\nthe nucleus would not normally emit any radiation (the stationary state hypothesis), but it would emit or\nabsorb a photon if it moved to a different orbit. The energy absorbed or emitted would reflect differences in the\norbital energies according to this equation:\n"]], ["block_5", ["In this equation, h is Planck\u2019s constant and Ei and Ef are the initial and final orbital energies, respectively. The\nabsolute value of the energy difference is used, since frequencies and wavelengths are always positive. Instead\nof allowing for continuous values of energy, Bohr assumed the energies of these electron orbitals were\nquantized:\n"]], ["block_6", ["In this expression, k is a constant comprising fundamental constants such as the electron mass and charge\nand Planck\u2019s constant. Inserting the expression for the orbit energies into the equation for \u0394E gives\n"]], ["block_7", ["or\n"]], ["block_8", ["which is identical to the Rydberg equation in which\n\u221e\nWhen Bohr calculated his theoretical value for\n"]], ["block_9", ["the Rydberg constant,\n\u221e \n"]], ["block_10", ["agreement. Since the Rydberg constant was one of the most precisely measured constants at that time, this\nlevel of agreement was astonishing and meant that Bohr\u2019s model was taken seriously, despite the many\nassumptions that Bohr needed to derive it.\n"]], ["block_11", ["The lowest few energy levels are shown in Figure 6.14. One of the fundamental laws of physics is that matter is\nmost stable with the lowest possible energy. Thus, the electron in a hydrogen atom usually moves in the n = 1\norbit, the orbit in which it has the lowest energy. When the electron is in this lowest energy orbit, the atom is\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["\u2022\nDescribe the Bohr model of the hydrogen atom\n"]], ["block_14", ["\u2022\nUse the Rydberg equation to calculate energies of light emitted or absorbed by hydrogen atoms\n"]]], "page_284": [["block_0", ["said to be in its ground electronic state (or simply ground state). If the atom receives energy from an outside\nsource, it is possible for the electron to move to an orbit with a higher n value and the atom is now in an\n excited electronic state (or simply an excited state) with a higher energy. When an electron transitions from\nan excited state (higher energy orbit) to a less excited state, or ground state, the difference in energy is emitted\nas a photon. Similarly, if a photon is absorbed by an atom, the energy of the photon moves an electron from a\nlower energy orbit up to a more excited one. We can relate the energy of electrons in atoms to what we learned\npreviously about energy. The law of conservation of energy says that we can neither create nor destroy energy.\nThus, if a certain amount of external energy is required to excite an electron from one energy level to another,\nthat same amount of energy will be liberated when the electron returns to its initial state (Figure 6.15).\n"]], ["block_1", ["Since Bohr\u2019s model involved only a single electron, it could also be applied to the single electron ions He, Li,\nBe, and so forth, which differ from hydrogen only in their nuclear charges, and so one-electron atoms and\nions are collectively referred to as hydrogen-like atoms. The energy expression for hydrogen-like atoms is a\ngeneralization of the hydrogen atom energy, in which Z is the nuclear charge (+1 for hydrogen, +2 for He, +3 for\nLi, and so on) and k has a value of 2.179\n10J.\n"]], ["block_2", ["The sizes of the circular orbits for hydrogen-like atoms are given in terms of their radii by the following\nexpression, in which\nis a constant called the Bohr radius, with a value of 5.292\n10m:\n"]], ["block_3", ["The equation also shows us that as the electron\u2019s energy increases (as n increases), the electron is found at\ngreater distances from the nucleus. This is implied by the inverse dependence of electrostatic attraction on\ndistance, since, as the electron moves away from the nucleus, the electrostatic attraction between it and the\nnucleus decreases and it is held less tightly in the atom. Note that as n gets larger and the orbits get larger,\n"]], ["block_4", ["their energies get closer to zero, and so the limits\n\u221e and\n\u221e imply that E = 0 corresponds to the\n"]], ["block_5", ["ionization limit where the electron is completely removed from the nucleus. Thus, for hydrogen in the ground\nstate n = 1, the ionization energy would be:\n"]], ["block_6", ["With three extremely puzzling paradoxes now solved (blackbody radiation, the photoelectric effect, and the\nhydrogen atom), and all involving Planck\u2019s constant in a fundamental manner, it became clear to most\nphysicists at that time that the classical theories that worked so well in the macroscopic world were\nfundamentally flawed and could not be extended down into the microscopic domain of atoms and molecules.\nUnfortunately, despite Bohr\u2019s remarkable achievement in deriving a theoretical expression for the Rydberg\nconstant, he was unable to extend his theory to the next simplest atom, He, which only has two electrons.\nBohr\u2019s model was severely flawed, since it was still based on the classical mechanics notion of precise orbits, a\nconcept that was later found to be untenable in the microscopic domain, when a proper model of quantum\nmechanics was developed to supersede classical mechanics.\n"]], ["block_7", ["\u221e\n"]], ["block_8", [" 6.2 \u2022 The Bohr Model \n 271 \n"]]], "page_285": [["block_0", [" 272 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", [" FIGURE 6.14 \nQuantum numbers and energy levels in a hydrogen atom. The more negative the calculated value,\n"]], ["block_2", ["the lower the energy.\n"]], ["block_3", [" Calculating the Energy of an Electron in a Bohr Orbit \n"]], ["block_4", ["Early researchers were very excited when they were able to predict the energy of an electron at a particular\ndistance from the nucleus in a hydrogen atom. If a spark promotes the electron in a hydrogen atom into an\norbit with n = 3, what is the calculated energy, in joules, of the electron?\n"]], ["block_5", [" Solution \n"]], ["block_6", ["The energy of the electron is given by this equation:\n"]], ["block_7", ["The atomic number, Z, of hydrogen is 1; k = 2.179\n10J; and the electron is characterized by an n value of\n"]], ["block_8", ["3. Thus,\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["The electron in Figure 6.15 is promoted even further to an orbit with n = 6. What is its new energy?\n"]], ["block_11", [" Answer: \n\u22126.053\n10J\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["EXAMPLE 6.4\n"]], ["block_14", [{"image_0": "285_0.png", "coords": [189, 57, 423, 254]}]]], "page_286": [["block_0", [{"image_0": "286_0.png", "coords": [72, 57, 540, 381]}]], ["block_1", [" FIGURE 6.15 \nThe horizontal lines show the relative energy of orbits in the Bohr model of the hydrogen atom, and\n"]], ["block_2", ["the vertical arrows depict the energy of photons absorbed (left) or emitted (right) as electrons move between these\norbits.\n"]], ["block_3", [" Calculating the Energy and Wavelength of Electron Transitions in a One\u2013electron (Bohr) \n System \n"]], ["block_4", ["What is the energy (in joules) and the wavelength (in meters) of the line in the spectrum of hydrogen that\nrepresents the movement of an electron from Bohr orbit with n = 4 to the orbit with n = 6? In what part of the\nelectromagnetic spectrum do we find this radiation?\n"]], ["block_5", [" Solution \n"]], ["block_6", ["In this case, the electron starts out with n = 4, so n1 = 4. It comes to rest in the n = 6 orbit, so n2 = 6. The\ndifference in energy between the two states is given by this expression:\n"]], ["block_7", ["This energy difference is positive, indicating a photon enters the system (is absorbed) to excite the electron\n"]], ["block_8", ["EXAMPLE 6.5\n"]], ["block_9", [" 6.2 \u2022 The Bohr Model \n 273 \n"]]], "page_287": [["block_0", [" 274 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", ["from the n = 4 orbit up to the n = 6 orbit. The wavelength of a photon with this energy is found by the\nexpression\nRearrangement gives:\n"]], ["block_2", ["From the illustration of the electromagnetic spectrum in Electromagnetic Energy, we can see that this\nwavelength is found in the infrared portion of the electromagnetic spectrum.\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["What is the energy in joules and the wavelength in meters of the photon produced when an electron falls from\nthe n = 5 to the n = 3 level in a Heion (Z = 2 for He)?\n"]], ["block_5", [" Answer: \n6.198\n10J; 3.205\n10m\n"]], ["block_6", ["Bohr\u2019s model of the hydrogen atom provides insight into the behavior of matter at the microscopic level, but it\ndoes not account for electron\u2013electron interactions in atoms with more than one electron. It does introduce\nseveral important features of all models used to describe the distribution of electrons in an atom. These\nfeatures include the following:\n"]], ["block_7", ["Of these features, the most important is the postulate of quantized energy levels for an electron in an atom. As\na consequence, the model laid the foundation for the quantum mechanical model of the atom. Bohr won a\nNobel Prize in Physics for his contributions to our understanding of the structure of atoms and how that is\nrelated to line spectra emissions.\n"]], ["block_8", [" 6.3 Development of Quantum Theory \n"]], ["block_9", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_10", ["Bohr\u2019s model explained the experimental data for the hydrogen atom and was widely accepted, but it also\nraised many questions. Why did electrons orbit at only fixed distances defined by a single quantum number n\n= 1, 2, 3, and so on, but never in between? Why did the model work so well describing hydrogen and one-\nelectron ions, but could not correctly predict the emission spectrum for helium or any larger atoms? To answer\nthese questions, scientists needed to completely revise the way they thought about matter.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["\u2022\nThe energies of electrons (energy levels) in an atom are quantized, described by quantum numbers :\ninteger numbers having only specific allowed value and used to characterize the arrangement of electrons\nin an atom.\n"]], ["block_13", ["\u2022\nAn electron\u2019s energy increases with increasing distance from the nucleus.\n"]], ["block_14", ["\u2022\nThe discrete energies (lines) in the spectra of the elements result from quantized electronic energies.\n"]], ["block_15", ["\u2022\nExtend the concept of wave\u2013particle duality that was observed in electromagnetic radiation to matter as well\n"]], ["block_16", ["\u2022\nUnderstand the general idea of the quantum mechanical description of electrons in an atom, and that it uses\nthe notion of three-dimensional wave functions, or orbitals, that define the distribution of probability to find an\nelectron in a particular part of space\n"]], ["block_17", ["\u2022\nList and describe traits of the four quantum numbers that form the basis for completely specifying the state of\nan electron in an atom\n"]]], "page_288": [["block_0", [" Behavior in the Microscopic World \n"]], ["block_1", ["We know how matter behaves in the macroscopic world\u2014objects that are large enough to be seen by the naked\neye follow the rules of classical physics. A billiard ball moving on a table will behave like a particle: It will\ncontinue in a straight line unless it collides with another ball or the table cushion, or is acted on by some other\nforce (such as friction). The ball has a well-defined position and velocity (or a well-defined momentum, p = mv,\ndefined by mass m and velocity v) at any given moment. In other words, the ball is moving in a classical\ntrajectory. This is the typical behavior of a classical object.\n"]], ["block_2", ["When waves interact with each other, they show interference patterns that are not displayed by macroscopic\nparticles such as the billiard ball. For example, interacting waves on the surface of water can produce\ninterference patterns similar to those shown on Figure 6.16. This is a case of wave behavior on the\nmacroscopic scale, and it is clear that particles and waves are very different phenomena in the macroscopic\nrealm.\n"]], ["block_3", [" FIGURE 6.16 \nAn interference pattern on the water surface is formed by interacting waves. The waves are caused\n"]], ["block_4", ["by reflection of water from the rocks. (credit: modification of work by Sukanto Debnath)\n"]], ["block_5", ["As technological improvements allowed scientists to probe the microscopic world in greater detail, it became\nincreasingly clear by the 1920s that very small pieces of matter follow a different set of rules from those we\nobserve for large objects. The unquestionable separation of waves and particles was no longer the case for the\nmicroscopic world.\n"]], ["block_6", ["One of the first people to pay attention to the special behavior of the microscopic world was Louis de Broglie.\nHe asked the question: If electromagnetic radiation can have particle-like character, can electrons and other\nsubmicroscopic particles exhibit wavelike character? In his 1925 doctoral dissertation, de Broglie extended\nthe wave\u2013particle duality of light that Einstein used to resolve the photoelectric-effect paradox to material\nparticles. He predicted that a particle with mass m and velocity v (that is, with linear momentum p) should also\nexhibit the behavior of a wave with a wavelength value \u03bb, given by this expression in which h is the familiar\nPlanck\u2019s constant:\n"]], ["block_7", ["This is called the de Broglie wavelength. Unlike the other values of \u03bb discussed in this chapter, the de Broglie\nwavelength is a characteristic of particles and other bodies, not electromagnetic radiation (note that this\nequation involves velocity [v, m/s], not frequency [\u03bd, Hz]. Although these two symbols appear nearly identical,\nthey mean very different things). Where Bohr had postulated the electron as being a particle orbiting the\nnucleus in quantized orbits, de Broglie argued that Bohr\u2019s assumption of quantization can be explained if the\nelectron is considered not as a particle, but rather as a circular standing wave such that only an integer\nnumber of wavelengths could fit exactly within the orbit (Figure 6.17).\n"]], ["block_8", [{"image_0": "288_0.png", "coords": [247, 228, 364, 325]}]], ["block_9", [" 6.3 \u2022 Development of Quantum Theory \n 275 \n"]]], "page_289": [["block_0", [" 276 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", [" FIGURE 6.17 \nIf an electron is viewed as a wave circling around the nucleus, an integer number of wavelengths\n"]], ["block_2", ["must fit into the orbit for this standing wave behavior to be possible.\n"]], ["block_3", ["For a circular orbit of radius r, the circumference is 2\u03c0r, and so de Broglie\u2019s condition is:\n"]], ["block_4", ["Shortly after de Broglie proposed the wave nature of matter, two scientists at Bell Laboratories, C. J. Davisson\nand L. H. Germer, demonstrated experimentally that electrons can exhibit wavelike behavior by showing an\ninterference pattern for electrons travelling through a regular atomic pattern in a crystal. The regularly spaced\natomic layers served as slits, as used in other interference experiments. Since the spacing between the layers\nserving as slits needs to be similar in size to the wavelength of the tested wave for an interference pattern to\nform, Davisson and Germer used a crystalline nickel target for their \u201cslits,\u201d since the spacing of the atoms\nwithin the lattice was approximately the same as the de Broglie wavelengths of the electrons that they used.\nFigure 6.18 shows an interference pattern. It is strikingly similar to the interference patterns for light shown in\nElectromagnetic Energy for light passing through two closely spaced, narrow slits. The wave\u2013particle duality of\nmatter can be seen in Figure 6.18 by observing what happens if electron collisions are recorded over a long\nperiod of time. Initially, when only a few electrons have been recorded, they show clear particle-like behavior,\nhaving arrived in small localized packets that appear to be random. As more and more electrons arrived and\nwere recorded, a clear interference pattern that is the hallmark of wavelike behavior emerged. Thus, it appears\nthat while electrons are small localized particles, their motion does not follow the equations of motion implied\nby classical mechanics, but instead it is governed by some type of a wave equation. Thus the wave\u2013particle\nduality first observed with photons is actually a fundamental behavior intrinsic to all quantum particles.\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", [{"image_0": "289_0.png", "coords": [189, 57, 423, 159]}]]], "page_290": [["block_0", [{"image_0": "290_0.png", "coords": [72, 57, 540, 411]}]], ["block_1", [" FIGURE 6.18 \n(a) The interference pattern for electrons passing through very closely spaced slits demonstrates\n"]], ["block_2", ["that quantum particles such as electrons can exhibit wavelike behavior. (b) The experimental results illustrated here\ndemonstrate the wave\u2013particle duality in electrons.\n"]], ["block_3", ["View the Dr. Quantum \u2013 Double Slit Experiment cartoon (http://openstax.org/l/16duality) for an easy-to-\nunderstand description of wave\u2013particle duality and the associated experiments.\n"]], ["block_4", [" Calculating the Wavelength of a Particle \n"]], ["block_5", ["If an electron travels at a velocity of 1.000\n10m sand has a mass of 9.109\n10g, what is its\n"]], ["block_6", ["wavelength?\n"]], ["block_7", [" Solution \n"]], ["block_8", ["We can use de Broglie\u2019s equation to solve this problem, but we first must do a unit conversion of Planck\u2019s\nconstant. You learned earlier that 1 J = 1 kg m/s. Thus, we can write h = 6.626\n10J s as 6.626\n10kg\n"]], ["block_9", ["m/s.\n"]], ["block_10", ["LINK TO LEARNING\n"]], ["block_11", ["EXAMPLE 6.6\n"]], ["block_12", [" 6.3 \u2022 Development of Quantum Theory \n 277 \n"]]], "page_291": [["block_0", [" 278 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", ["\u210f\nthe value of Planck\u2019s constant divided by 2\u03c0).\n"]], ["block_2", ["Werner Heisenberg considered the limits of how accurately we can measure properties of an electron or other\nmicroscopic particles. He determined that there is a fundamental limit to how accurately one can measure\nboth a particle\u2019s position and its momentum simultaneously. The more accurately we measure the momentum\nof a particle, the less accurately we can determine its position at that time, and vice versa. This is summed up\nin what we now call the Heisenberg uncertainty principle : It is fundamentally impossible to determine\nsimultaneously and exactly both the momentum and the position of a particle. For a particle of mass m moving\nwith velocity vx in the x direction (or equivalently with momentum px), the product of the uncertainty in the\n"]], ["block_3", ["This is a small value, but it is significantly larger than the size of an electron in the classical (particle) view.\nThis size is the same order of magnitude as the size of an atom. This means that electron wavelike behavior is\ngoing to be noticeable in an atom.\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["Calculate the wavelength of a softball with a mass of 100 g traveling at a velocity of 35 m s, assuming that it\ncan be modeled as a single particle.\n"]], ["block_6", [" Answer: \n1.9\n10m.\n"]], ["block_7", ["We never think of a thrown softball having a wavelength, since this wavelength is so small it is impossible for\nour senses or any known instrument to detect (strictly speaking, the wavelength of a real baseball would\ncorrespond to the wavelengths of its constituent atoms and molecules, which, while much larger than this\nvalue, would still be microscopically tiny). The de Broglie wavelength is only appreciable for matter that has a\nvery small mass and/or a very high velocity.\n"]], ["block_8", ["position, \u0394x, and the uncertainty in the momentum, \u0394px , must be greater than or equal to\n"]], ["block_9", ["This equation allows us to calculate the limit to how precisely we can know both the simultaneous position of\nan object and its momentum. For example, if we improve our measurement of an electron\u2019s position so that the\nuncertainty in the position (\u0394x) has a value of, say, 1 pm (10m, about 1% of the diameter of a hydrogen\natom), then our determination of its momentum must have an uncertainty with a value of at least\n"]], ["block_10", ["The value of \u0127 is not large, so the uncertainty in the position or momentum of a macroscopic object like a\nbaseball is too insignificant to observe. However, the mass of a microscopic object such as an electron is small\nenough that the uncertainty can be large and significant.\n"]], ["block_11", ["It should be noted that Heisenberg\u2019s uncertainty principle is not just limited to uncertainties in position and\nmomentum, but it also links other dynamical variables. For example, when an atom absorbs a photon and\nmakes a transition from one energy state to another, the uncertainty in the energy and the uncertainty in the\n"]], ["block_12", ["time required for the transition are similarly related, as \u0394E \u0394t \u2265\n"]], ["block_13", ["Heisenberg\u2019s principle imposes ultimate limits on what is knowable in science. The uncertainty principle can\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["\u210f\n"]], ["block_16", ["\u210f\n"]], ["block_17", ["\u210f\n"]], ["block_18", ["(where\n"]]], "page_292": [["block_0", ["be shown to be a consequence of wave\u2013particle duality, which lies at the heart of what distinguishes modern\nquantum theory from classical mechanics.\n"]], ["block_1", ["Read this article (http://openstax.org/l/16uncertainty) that describes a recent macroscopic demonstration of\nthe uncertainty principle applied to microscopic objects.\n"]], ["block_2", [" The Quantum\u2013Mechanical Model of an Atom \n"]], ["block_3", ["Shortly after de Broglie published his ideas that the electron in a hydrogen atom could be better thought of as\nbeing a circular standing wave instead of a particle moving in quantized circular orbits, Erwin Schr\u00f6dinger\nextended de Broglie\u2019s work by deriving what is today known as the Schr\u00f6dinger equation. When Schr\u00f6dinger\napplied his equation to hydrogen-like atoms, he was able to reproduce Bohr\u2019s expression for the energy and,\nthus, the Rydberg formula governing hydrogen spectra. Schr\u00f6dinger described electrons as three-dimensional\nstationary waves, or wavefunctions , represented by the Greek letter psi, \u03c8. A few years later, Max Born\nproposed an interpretation of the wavefunction \u03c8 that is still accepted today: Electrons are still particles, and\nso the waves represented by \u03c8 are not physical waves but, instead, are complex probability amplitudes. The\nsquare of the magnitude of a wavefunction\ndescribes the probability of the quantum particle being\n"]], ["block_4", ["present near a certain location in space. This means that wavefunctions can be used to determine the\ndistribution of the electron\u2019s density with respect to the nucleus in an atom. In the most general form, the\nSchr\u00f6dinger equation can be written as:\n"]], ["block_5", ["particle (such as an electron in an atom), \u03c8 is the wavefunction of this particle that can be used to find the\nspecial distribution of the probability of finding the particle, and\nis the actual value of the total energy of the\n"]], ["block_6", ["particle.\n"]], ["block_7", ["Schr\u00f6dinger\u2019s work, as well as that of Heisenberg and many other scientists following in their footsteps, is\ngenerally referred to as quantum mechanics .\n"]], ["block_8", ["You may also have heard of Schr\u00f6dinger because of his famous thought experiment. This story\n(http://openstax.org/l/16superpos) explains the concepts of superposition and entanglement as related to a cat\nin a box with poison.\n"]], ["block_9", [" Understanding Quantum Theory of Electrons in Atoms \n"]], ["block_10", ["The goal of this section is to understand the electron orbitals (location of electrons in atoms), their different\nenergies, and other properties. The use of quantum theory provides the best understanding to these topics.\nThis knowledge is a precursor to chemical bonding.\n"]], ["block_11", ["As was described previously, electrons in atoms can exist only on discrete energy levels but not between them.\nIt is said that the energy of an electron in an atom is quantized, that is, it can be equal only to certain specific\nvalues and can jump from one energy level to another but not transition smoothly or stay between these levels.\n"]], ["block_12", ["The energy levels are labeled with an n value, where n = 1, 2, 3, \u2026. Generally speaking, the energy of an\nelectron in an atom is greater for greater values of n. This number, n, is referred to as the principal quantum\nnumber. The principal quantum number defines the location of the energy level. It is essentially the same\nconcept as the n in the Bohr atom description. Another name for the principal quantum number is the shell\nnumber. The shells of an atom can be thought of concentric circles radiating out from the nucleus. The\nelectrons that belong to a specific shell are most likely to be found within the corresponding circular area. The\nfurther we proceed from the nucleus, the higher the shell number, and so the higher the energy level (Figure\n6.19). The positively charged protons in the nucleus stabilize the electronic orbitals by electrostatic attraction\n"]], ["block_13", ["is the Hamiltonian operator, a set of mathematical operations representing the total energy of the quantum\n"]], ["block_14", ["LINK TO LEARNING\n"]], ["block_15", ["LINK TO LEARNING\n"]], ["block_16", [" 6.3 \u2022 Development of Quantum Theory \n 279 \n"]]], "page_293": [["block_0", [" 280 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", ["between the positive charges of the protons and the negative charges of the electrons. So the further away the\nelectron is from the nucleus, the greater the energy it has.\n"]], ["block_2", ["This quantum mechanical model for where electrons reside in an atom can be used to look at electronic\ntransitions, the events when an electron moves from one energy level to another. If the transition is to a higher\nenergy level, energy is absorbed, and the energy change has a positive value. To obtain the amount of energy\nnecessary for the transition to a higher energy level, a photon is absorbed by the atom. A transition to a lower\nenergy level involves a release of energy, and the energy change is negative. This process is accompanied by\nemission of a photon by the atom. The following equation summarizes these relationships and is based on the\nhydrogen atom:\n"]], ["block_3", ["The values nf and ni are the final and initial energy states of the electron. Example 6.5 in the previous section\nof the chapter demonstrates calculations of such energy changes.\n"]], ["block_4", ["The principal quantum number is one of three quantum numbers used to characterize an orbital. An atomic \n orbital is a general region in an atom within which an electron is most probable to reside. The quantum\nmechanical model specifies the probability of finding an electron in the three-dimensional space around the\nnucleus and is based on solutions of the Schr\u00f6dinger equation. In addition, the principal quantum number\ndefines the energy of an electron in a hydrogen or hydrogen-like atom or an ion (an atom or an ion with only\none electron) and the general region in which discrete energy levels of electrons in a multi-electron atoms and\nions are located.\n"]], ["block_5", ["Another quantum number is l, the secondary (angular momentum) quantum number . It is an integer that\nmay take the values, l = 0, 1, 2, \u2026, n \u2013 1. This means that an orbital with n = 1 can have only one value of l, l = 0,\nwhereas n = 2 permits l = 0 and l = 1, and so on. Whereas the principal quantum number, n, defines the general\nsize and energy of the orbital, the secondary quantum number l specifies the shape of the orbital. Orbitals with\nthe same value of l define a subshell .\n"]], ["block_6", ["Orbitals with l = 0 are called s orbitals and they make up the s subshells. The value l = 1 corresponds to the p\norbitals. For a given n, p orbitals constitute a p subshell (e.g., 3p if n = 3). The orbitals with l = 2 are called the d \n orbitals , followed by the f-, g-, and h-orbitals for l = 3, 4, and 5.\n"]], ["block_7", ["There are certain distances from the nucleus at which the probability density of finding an electron located at a\nparticular orbital is zero. In other words, the value of the wavefunction \u03c8 is zero at this distance for this orbital.\nSuch a value of radius r is called a radial node. The number of radial nodes in an orbital is n \u2013 l \u2013 1.\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", [" FIGURE 6.19 \nDifferent shells are numbered by principal quantum numbers.\n"]], ["block_10", [{"image_0": "293_0.png", "coords": [189, 89, 423, 248]}]]], "page_294": [["block_0", [{"image_0": "294_0.png", "coords": [72, 57, 540, 421]}]], ["block_1", [" FIGURE 6.20 \nThe graphs show the probability (y axis) of finding an electron for the 1s, 2s, 3s orbitals as a function\n"]], ["block_2", ["of distance from the nucleus.\n"]], ["block_3", ["Consider the examples in Figure 6.20. The orbitals depicted are of the s type, thus l = 0 for all of them. It can be\nseen from the graphs of the probability densities that there are 1 \u2013 0 \u2013 1 = 0 places where the density is zero\n(nodes) for 1s (n = 1), 2 \u2013 0 \u2013 1 = 1 node for 2s, and 3 \u2013 0 \u2013 1 = 2 nodes for the 3s orbitals.\n"]], ["block_4", ["The s subshell electron density distribution is spherical and the p subshell has a dumbbell shape. The d and f \n orbitals are more complex. These shapes represent the three-dimensional regions within which the electron\nis likely to be found.\n"]], ["block_5", [" 6.3 \u2022 Development of Quantum Theory \n 281 \n"]]], "page_295": [["block_0", [" 282 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", [{"image_0": "295_0.png", "coords": [72, 57, 540, 633]}]], ["block_2", ["The magnetic quantum number , ml, specifies the relative spatial orientation of a particular orbital. Generally\nspeaking, ml can be equal to \u2013l, \u2013(l \u2013 1), \u2026, 0, \u2026, (l \u2013 1), l. The total number of possible orbitals with the same\nvalue of l (that is, in the same subshell) is 2l + 1. Thus, there is one s-orbital in an s subshell (l = 0), there are\nthree p-orbitals in a p subshell (l = 1), five d-orbitals in a d subshell (l = 2), seven f-orbitals in an f subshell (l =\n3), and so forth. The principal quantum number defines the general value of the electronic energy. The angular\nmomentum quantum number determines the shape of the orbital. And the magnetic quantum number\n"]], ["block_3", [" Access for free at openstax.org \n"]], ["block_4", [" FIGURE 6.21 \nShapes of s, p, d, and f orbitals.\n"]]], "page_296": [["block_0", ["Figure 6.22 illustrates the energy levels for various orbitals. The number before the orbital name (such as 2s,\n3p, and so forth) stands for the principal quantum number, n. The letter in the orbital name defines the\nsubshell with a specific angular momentum quantum number l = 0 for s orbitals, 1 for p orbitals, 2 for d\norbitals. Finally, there are more than one possible orbitals for l \u2265 1, each corresponding to a specific value of\nml. In the case of a hydrogen atom or a one-electron ion (such as He, Li, and so on), energies of all the\norbitals with the same n are the same. This is called a degeneracy, and the energy levels for the same principal\nquantum number, n, are called degenerate orbitals . However, in atoms with more than one electron, this\ndegeneracy is eliminated by the electron\u2013electron interactions, and orbitals that belong to different subshells\nhave different energies, as shown on Figure 6.22. Orbitals within the same subshell are still degenerate and\nhave the same energy.\n"]], ["block_1", ["z component of the spin being negative and\nAny electron, regardless of the atomic orbital it is\n"]], ["block_2", ["specifies orientation of the orbital in space, as can be seen in Figure 6.21.\n"]], ["block_3", [{"image_0": "296_0.png", "coords": [72, 76, 540, 248]}]], ["block_4", ["While the three quantum numbers discussed in the previous paragraphs work well for describing electron\norbitals, some experiments showed that they were not sufficient to explain all observed results. It was\ndemonstrated in the 1920s that when hydrogen-line spectra are examined at extremely high resolution, some\nlines are actually not single peaks but, rather, pairs of closely spaced lines. This is the so-called fine structure\nof the spectrum, and it implies that there are additional small differences in energies of electrons even when\nthey are located in the same orbital. These observations led Samuel Goudsmit and George Uhlenbeck to\npropose that electrons have a fourth quantum number. They called this the spin quantum number , or m s .\n"]], ["block_5", ["The other three quantum numbers, n, l, and ml, are properties of specific atomic orbitals that also define in\nwhat part of the space an electron is most likely to be located. Orbitals are a result of solving the Schr\u00f6dinger\nequation for electrons in atoms. The electron spin is a different kind of property. It is a completely quantum\nphenomenon with no analogues in the classical realm. In addition, it cannot be derived from solving the\nSchr\u00f6dinger equation and is not related to the normal spatial coordinates (such as the Cartesian x, y, and z).\nElectron spin describes an intrinsic electron \"rotation\" or \"spinning.\" Each electron acts as a tiny magnet or a\ntiny rotating object with an angular momentum, or as a loop with an electric current, even though this rotation\nor current cannot be observed in terms of spatial coordinates.\n"]], ["block_6", ["The magnitude of the overall electron spin can only have one value, and an electron can only \u201cspin\u201d in one of\ntwo quantized states. One is termed the \u03b1 state, with the z component of the spin being in the positive direction\n"]], ["block_7", ["of the z axis. This corresponds to the spin quantum number\nThe other is called the \u03b2 state, with the\n"]], ["block_8", ["located in, can only have one of those two values of the spin quantum number. The energies of electrons having\n"]], ["block_9", ["and\nare different if an external magnetic field is applied.\n"]], ["block_10", [" FIGURE 6.22 \nThe chart shows the energies of electron orbitals in a multi-electron atom.\n"]], ["block_11", [" 6.3 \u2022 Development of Quantum Theory \n 283 \n"]]], "page_297": [["block_0", [" 284 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", ["Figure 6.23 illustrates this phenomenon. An electron acts like a tiny magnet. Its moment is directed up (in the\npositive direction of the z axis) for the\nspin quantum number and down (in the negative z direction) for the\n"]], ["block_2", ["spin quantum number of\nA magnet has a lower energy if its magnetic moment is aligned with the external\n"]], ["block_3", ["magnetic field (the left electron on Figure 6.23) and a higher energy for the magnetic moment being opposite\nto the applied field. This is why an electron with\nhas a slightly lower energy in an external field in the\n"]], ["block_4", ["positive z direction, and an electron with\nhas a slightly higher energy in the same field. This is true\n"]], ["block_5", ["even for an electron occupying the same orbital in an atom. A spectral line corresponding to a transition for\nelectrons from the same orbital but with different spin quantum numbers has two possible values of energy;\nthus, the line in the spectrum will show a fine structure splitting.\n"]], ["block_6", [" The Pauli Exclusion Principle \n"]], ["block_7", ["An electron in an atom is completely described by four quantum numbers: n, l, ml, and ms. The first three\nquantum numbers define the orbital and the fourth quantum number describes the intrinsic electron property\ncalled spin. An Austrian physicist Wolfgang Pauli formulated a general principle that gives the last piece of\ninformation that we need to understand the general behavior of electrons in atoms. The Pauli exclusion \n principle can be formulated as follows: No two electrons in the same atom can have exactly the same set of all\nthe four quantum numbers. What this means is that two electrons can share the same orbital (the same set of\nthe quantum numbers n, l, and ml) only if their spin quantum numbers ms have different values. Since the spin\nquantum number can only have two values\nno more than two electrons can occupy the same orbital\n"]], ["block_8", ["(and if two electrons are located in the same orbital, they must have opposite spins). Therefore, any atomic\norbital can be populated by only zero, one, or two electrons.\n"]], ["block_9", ["The properties and meaning of the quantum numbers of electrons in atoms are briefly summarized in Table\n6.1.\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [" Name \n Symbol \n Allowed \n values \n Physical meaning \n"]], ["block_12", ["principal quantum number\nn\n1, 2, 3, 4,\n\u2026.\n"]], ["block_13", ["angular momentum or\nazimuthal quantum number\nl\n0 \u2264 l \u2264 n\n\u2013 1\nsubshell, the shape of the orbital\n"]], ["block_14", ["magnetic quantum number\nml\n"]], ["block_15", [" FIGURE 6.23 \nElectrons with spin values\nin an external magnetic field.\n"]], ["block_16", [{"image_0": "297_0.png", "coords": [189, 57, 423, 203]}]], ["block_17", [" Quantum Numbers, Their Properties, and Significance \n"]], ["block_18", ["\u2013 l \u2264 ml \u2264\nl\norientation of the orbital\n"]], ["block_19", ["shell, the general region for the value of energy\nfor an electron on the orbital\n"]]], "page_298": [["block_0", [" TABLE 6.1 \n"]], ["block_1", [" Working with Shells and Subshells \n"]], ["block_2", ["Indicate the number of subshells, the number of orbitals in each subshell, and the values of l and ml for the\norbitals in the n = 4 shell of an atom.\n"]], ["block_3", [" Solution \n"]], ["block_4", ["For n = 4, l can have values of 0, 1, 2, and 3. Thus, s, p, d, and f subshells are found in the n = 4 shell of an atom.\nFor l = 0 (the s subshell), ml can only be 0. Thus, there is only one 4s orbital. For l = 1 (p-type orbitals), m can\nhave values of \u20131, 0, +1, so we find three 4p orbitals. For l = 2 (d-type orbitals), ml can have values of \u20132, \u20131, 0,\n+1, +2, so we have five 4d orbitals. When l = 3 (f-type orbitals), ml can have values of \u20133, \u20132, \u20131, 0, +1, +2, +3,\nand we can have seven 4f orbitals. Thus, we find a total of 16 orbitals in the n = 4 shell of an atom.\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["Identify the subshell in which electrons with the following quantum numbers are found: (a) n = 3, l = 1; (b) n =\n5, l = 3; (c) n = 2, l = 0.\n"]], ["block_7", [" Answer: \n(a) 3p (b) 5f (c) 2s\n"]], ["block_8", [" Maximum Number of Electrons \n"]], ["block_9", ["Calculate the maximum number of electrons that can occupy a shell with (a) n = 2, (b) n = 5, and (c) n as a\nvariable. Note you are only looking at the orbitals with the specified n value, not those at lower energies.\n"]], ["block_10", [" Solution \n"]], ["block_11", ["(a) When n = 2, there are four orbitals (a single 2s orbital, and three orbitals labeled 2p). These four orbitals can\ncontain eight electrons.\n"]], ["block_12", ["(b) When n = 5, there are five subshells of orbitals that we need to sum:\n"]], ["block_13", [" Name \n Symbol \n Allowed \n values \n Physical meaning \n"]], ["block_14", ["spin quantum number\nms\n"]], ["block_15", ["EXAMPLE 6.7\n"]], ["block_16", ["EXAMPLE 6.8\n"]], ["block_17", [" Quantum Numbers, Their Properties, and Significance \n"]], ["block_18", ["direction of the intrinsic quantum \u201cspinning\u201d of\nthe electron\n"]], ["block_19", [" 6.3 \u2022 Development of Quantum Theory \n 285 \n"]]], "page_299": [["block_0", [" 286 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", [" Answer: \nn = 4\n"]], ["block_2", ["Again, each orbital holds two electrons, so 50 electrons can fit in this shell.\n"]], ["block_3", ["(c) The number of orbitals in any shell n will equal n. There can be up to two electrons in each orbital, so the\nmaximum number of electrons will be 2\nn.\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["If a shell contains a maximum of 32 electrons, what is the principal quantum number, n?\n"]], ["block_6", [" Working with Quantum Numbers \n"]], ["block_7", ["Complete the following table for atomic orbitals:\n"]], ["block_8", [" Solution \n"]], ["block_9", ["The table can be completed using the following rules:\n"]], ["block_10", [" Check Your Learning \n"]], ["block_11", ["How many orbitals have l = 2 and n = 3?\n"]], ["block_12", [" Answer: \nThe five degenerate 3d orbitals\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", ["\u2022\nThe orbital designation is nl, where l = 0, 1, 2, 3, 4, 5, \u2026 is mapped to the letter sequence s, p, d, f, g, h, \u2026,\n"]], ["block_15", ["\u2022\nThe ml degeneracy is the number of orbitals within an l subshell, and so is 2l + 1 (there is one s orbital,\nthree p orbitals, five d orbitals, seven f orbitals, and so forth).\n"]], ["block_16", ["\u2022\nThe number of radial nodes is equal to n \u2013 l \u2013 1.\n"]], ["block_17", ["EXAMPLE 6.9\n"]], ["block_18", [" Orbita l \n n \n l \nm l dege n eracy\nRadia l n odes ( n o.)\n"]], ["block_19", ["4f\n"]], ["block_20", ["5d\n"]], ["block_21", [" Orbita l \n n \n l \nm l dege n eracy\nRadia l n odes ( n o.)\n"]], ["block_22", ["4f\n4\n3\n7\n0\n"]], ["block_23", ["4p\n4\n1\n3\n2\n"]], ["block_24", ["7f\n7\n3\n7\n3\n"]], ["block_25", ["5d\n5\n2\n5\n2\n"]], ["block_26", ["4\n1\n"]], ["block_27", ["7\n7\n3\n"]]], "page_300": [["block_0", [" 6.4 Electronic Structure of Atoms (Electron Configurations) \n"]], ["block_1", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_2", ["Having introduced the basics of atomic structure and quantum mechanics, we can use our understanding of\nquantum numbers to determine how atomic orbitals relate to one another. This allows us to determine which\norbitals are occupied by electrons in each atom. The specific arrangement of electrons in orbitals of an atom\ndetermines many of the chemical properties of that atom.\n"]], ["block_3", [" Orbital Energies and Atomic Structure \n"]], ["block_4", ["The energy of atomic orbitals increases as the principal quantum number, n, increases. In any atom with two\nor more electrons, the repulsion between the electrons makes energies of subshells with different values of l\ndiffer so that the energy of the orbitals increases within a shell in the order s < p < d < f. Figure 6.24 depicts\nhow these two trends in increasing energy relate. The 1s orbital at the bottom of the diagram is the orbital with\nelectrons of lowest energy. The energy increases as we move up to the 2s and then 2p, 3s, and 3p orbitals,\nshowing that the increasing n value has more influence on energy than the increasing l value for small atoms.\nHowever, this pattern does not hold for larger atoms. The 3d orbital is higher in energy than the 4s orbital.\nSuch overlaps continue to occur frequently as we move up the chart.\n"]], ["block_5", [{"image_0": "300_0.png", "coords": [72, 334, 540, 574]}]], ["block_6", [" FIGURE 6.24 \nGeneralized energy-level diagram for atomic orbitals in an atom with two or more electrons (not to\n"]], ["block_7", ["scale).\n"]], ["block_8", ["Electrons in successive atoms on the periodic table tend to fill low-energy orbitals first. Thus, many students\nfind it confusing that, for example, the 5p orbitals fill immediately after the 4d, and immediately before the 6s.\nThe filling order is based on observed experimental results, and has been confirmed by theoretical\ncalculations. As the principal quantum number, n, increases, the size of the orbital increases and the electrons\nspend more time farther from the nucleus. Thus, the attraction to the nucleus is weaker and the energy\nassociated with the orbital is higher (less stabilized). But this is not the only effect we have to take into account.\nWithin each shell, as the value of l increases, the electrons are less penetrating (meaning there is less electron\ndensity found close to the nucleus), in the order s > p > d > f. Electrons that are closer to the nucleus slightly\nrepel electrons that are farther out, offsetting the more dominant electron\u2013nucleus attractions slightly (recall\n"]], ["block_9", ["\u2022\nDerive the predicted ground-state electron configurations of atoms\n"]], ["block_10", ["\u2022\nIdentify and explain exceptions to predicted electron configurations for atoms and ions\n"]], ["block_11", ["\u2022\nRelate electron configurations to element classifications in the periodic table\n"]], ["block_12", [" 6.4 \u2022 Electronic Structure of Atoms (Electron Configurations) \n 287 \n"]]], "page_301": [["block_0", [" 288 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", ["To determine the electron configuration for any particular atom, we can \u201cbuild\u201d the structures in the order of\natomic numbers. Beginning with hydrogen, and continuing across the periods of the periodic table, we add one\nproton at a time to the nucleus and one electron to the proper subshell until we have described the electron\nconfigurations of all the elements. This procedure is called the Aufbau principle , from the German word\nAufbau (\u201cto build up\u201d). Each added electron occupies the subshell of lowest energy available (in the order\nshown in Figure 6.24), subject to the limitations imposed by the allowed quantum numbers according to the\nPauli exclusion principle. Electrons enter higher-energy subshells only after lower-energy subshells have been\nfilled to capacity. Figure 6.26 illustrates the traditional way to remember the filling order for atomic orbitals.\nSince the arrangement of the periodic table is based on the electron configurations, Figure 6.27 provides an\nalternative method for determining the electron configuration. The filling order simply begins at hydrogen and\nincludes each subshell as you proceed in increasing Z order. For example, after filling the 3p block up to Ar, we\nsee the orbital will be 4s (K, Ca), followed by the 3d orbitals.\n"]], ["block_2", ["that all electrons have \u22121 charges, but nuclei have +Z charges). This phenomenon is called shielding and will\nbe discussed in more detail in the next section. Electrons in orbitals that experience more shielding are less\nstabilized and thus higher in energy. For small orbitals (1s through 3p), the increase in energy due to n is more\nsignificant than the increase due to l; however, for larger orbitals the two trends are comparable and cannot be\nsimply predicted. We will discuss methods for remembering the observed order.\n"]], ["block_3", ["The arrangement of electrons in the orbitals of an atom is called the electron configuration of the atom. We\ndescribe an electron configuration with a symbol that contains three pieces of information (Figure 6.25):\n"]], ["block_4", ["For example, the notation 2p(read \"two\u2013p\u2013four\") indicates four electrons in a p subshell (l = 1) with a\nprincipal quantum number (n) of 2. The notation 3d(read \"three\u2013d\u2013eight\") indicates eight electrons in the d\nsubshell (i.e., l = 2) of the principal shell for which n = 3.\n"]], ["block_5", [" FIGURE 6.25 \nThe diagram of an electron configuration specifies the subshell (n and l value, with letter symbol) and\n"]], ["block_6", ["superscript number of electrons.\n"]], ["block_7", [" The Aufbau Principle \n"]], ["block_8", [" FIGURE 6.26 \nThis diagram depicts the energy order for atomic orbitals and is useful for deriving ground-state\n"]], ["block_9", ["electron configurations.\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["1.\nThe number of the principal quantum shell, n,\n"]], ["block_12", ["2.\nThe letter that designates the orbital type (the subshell, l), and\n"]], ["block_13", ["3.\nA superscript number that designates the number of electrons in that particular subshell.\n"]], ["block_14", [{"image_0": "301_0.png", "coords": [130, 246, 481, 313]}]], ["block_15", [{"image_1": "301_1.png", "coords": [189, 525, 423, 694]}]]], "page_302": [["block_0", [{"image_0": "302_0.png", "coords": [72, 57, 545, 366]}]], ["block_1", [" FIGURE 6.27 \nThis partial periodic table shows electron configurations for the valence subshells of atoms. By\n"]], ["block_2", ["\u201cbuilding up\u201d from hydrogen, this table can be used to determine the electron configuration for atoms of most\nelements in the periodic table. (Electron configurations of the lanthanides and actinides are not accurately predicted\nby this simple approach. See Figure 6.29\n"]], ["block_3", ["We will now construct the ground-state electron configuration and orbital diagram for a selection of atoms in\nthe first and second periods of the periodic table. Orbital diagrams are pictorial representations of the\nelectron configuration, showing the individual orbitals and the pairing arrangement of electrons. We start with\na single hydrogen atom (atomic number 1), which consists of one proton and one electron. Referring to Figure\n6.26 or Figure 6.27, we would expect to find the electron in the 1s orbital. By convention, the\nvalue is\n"]], ["block_4", ["usually filled first. The electron configuration and the orbital diagram are:\n"]], ["block_5", [{"image_1": "302_1.png", "coords": [72, 510, 189, 551]}]], ["block_6", ["Following hydrogen is the noble gas helium, which has an atomic number of 2. The helium atom contains two\nprotons and two electrons. The first electron has the same four quantum numbers as the hydrogen atom\nelectron (n = 1, l = 0, ml = 0,\n). The second electron also goes into the 1s orbital and fills that orbital.\n"]], ["block_7", ["The second electron has the same n, l, and ml quantum numbers, but must have the opposite spin quantum\nnumber,\nThis is in accord with the Pauli exclusion principle: No two electrons in the same atom can\n"]], ["block_8", ["have the same set of four quantum numbers. For orbital diagrams, this means two arrows go in each box\n(representing two electrons in each orbital) and the arrows must point in opposite directions (representing\npaired spins). The electron configuration and orbital diagram of helium are:\n"]], ["block_9", [{"image_2": "302_2.png", "coords": [72, 667, 189, 708]}]], ["block_10", ["The n = 1 shell is completely filled in a helium atom.\n"]], ["block_11", [" 6.4 \u2022 Electronic Structure of Atoms (Electron Configurations) \n 289 \n"]]], "page_303": [["block_0", [" 290 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", ["The next atom is the alkali metal lithium with an atomic number of 3. The first two electrons in lithium fill the\n1s orbital and have the same sets of four quantum numbers as the two electrons in helium. The remaining\nelectron must occupy the orbital of next lowest energy, the 2s orbital (Figure 6.26 or Figure 6.27). Thus, the\nelectron configuration and orbital diagram of lithium are:\n"]], ["block_2", [{"image_0": "303_0.png", "coords": [72, 114, 306, 155]}]], ["block_3", ["An atom of the alkaline earth metal beryllium, with an atomic number of 4, contains four protons in the\nnucleus and four electrons surrounding the nucleus. The fourth electron fills the remaining space in the 2s\norbital.\n"]], ["block_4", [{"image_1": "303_1.png", "coords": [72, 202, 306, 243]}]], ["block_5", ["An atom of boron (atomic number 5) contains five electrons. The n = 1 shell is filled with two electrons and\nthree electrons will occupy the n = 2 shell. Because any s subshell can contain only two electrons, the fifth\nelectron must occupy the next energy level, which will be a 2p orbital. There are three degenerate 2p orbitals\n(ml = \u22121, 0, +1) and the electron can occupy any one of these p orbitals. When drawing orbital diagrams, we\ninclude empty boxes to depict any empty orbitals in the same subshell that we are filling.\n"]], ["block_6", [{"image_2": "303_2.png", "coords": [72, 315, 306, 356]}]], ["block_7", ["Carbon (atomic number 6) has six electrons. Four of them fill the 1s and 2s orbitals. The remaining two\nelectrons occupy the 2p subshell. We now have a choice of filling one of the 2p orbitals and pairing the\nelectrons or of leaving the electrons unpaired in two different, but degenerate, p orbitals. The orbitals are filled\nas described by Hund\u2019s rule : the lowest-energy configuration for an atom with electrons within a set of\ndegenerate orbitals is that having the maximum number of unpaired electrons. Thus, the two electrons in the\ncarbon 2p orbitals have identical n, l, and ms quantum numbers and differ in their ml quantum number (in\naccord with the Pauli exclusion principle). The electron configuration and orbital diagram for carbon are:\n"]], ["block_8", [{"image_3": "303_3.png", "coords": [72, 454, 306, 495]}]], ["block_9", ["Nitrogen (atomic number 7) fills the 1s and 2s subshells and has one electron in each of the three 2p orbitals,\nin accordance with Hund\u2019s rule. These three electrons have unpaired spins. Oxygen (atomic number 8) has a\npair of electrons in any one of the 2p orbitals (the electrons have opposite spins) and a single electron in each\nof the other two. Fluorine (atomic number 9) has only one 2p orbital containing an unpaired electron. All of the\nelectrons in the noble gas neon (atomic number 10) are paired, and all of the orbitals in the n = 1 and the n = 2\nshells are filled. The electron configurations and orbital diagrams of these four elements are:\n"]], ["block_10", [" Access for free at openstax.org \n"]]], "page_304": [["block_0", [{"image_0": "304_0.png", "coords": [72, 57, 306, 286]}]], ["block_1", ["The alkali metal sodium (atomic number 11) has one more electron than the neon atom. This electron must go\ninto the lowest-energy subshell available, the 3s orbital, giving a 1s2s2p3sconfiguration. The electrons\noccupying the outermost shell orbital(s) (highest value of n) are called valence electrons , and those occupying\nthe inner shell orbitals are called core electrons (Figure 6.28). Since the core electron shells correspond to\nnoble gas electron configurations, we can abbreviate electron configurations by writing the noble gas that\nmatches the core electron configuration, along with the valence electrons in a condensed format. For our\nsodium example, the symbol [Ne] represents core electrons, (1s2s2p) and our abbreviated or condensed\nconfiguration is [Ne]3s.\n"]], ["block_2", [" FIGURE 6.28 \nA core-abbreviated electron configuration (right) replaces the core electrons with the noble gas\n"]], ["block_3", ["symbol whose configuration matches the core electron configuration of the other element.\n"]], ["block_4", ["Similarly, the abbreviated configuration of lithium can be represented as [He]2s, where [He] represents the\nconfiguration of the helium atom, which is identical to that of the filled inner shell of lithium. Writing the\nconfigurations in this way emphasizes the similarity of the configurations of lithium and sodium. Both atoms,\nwhich are in the alkali metal family, have only one electron in a valence s subshell outside a filled set of inner\nshells.\n"]], ["block_5", ["The alkaline earth metal magnesium (atomic number 12), with its 12 electrons in a [Ne]3sconfiguration, is\nanalogous to its family member beryllium, [He]2s. Both atoms have a filled s subshell outside their filled inner\nshells. Aluminum (atomic number 13), with 13 electrons and the electron configuration [Ne]3s3p, is\nanalogous to its family member boron, [He]2s2p.\n"]], ["block_6", ["The electron configurations of silicon (14 electrons), phosphorus (15 electrons), sulfur (16 electrons), chlorine\n(17 electrons), and argon (18 electrons) are analogous in the electron configurations of their outer shells to\ntheir corresponding family members carbon, nitrogen, oxygen, fluorine, and neon, respectively, except that\nthe principal quantum number of the outer shell of the heavier elements has increased by one to n = 3. Figure\n6.29 shows the lowest energy, or ground-state, electron configuration for these elements as well as that for\natoms of each of the known elements.\n"]], ["block_7", [{"image_1": "304_1.png", "coords": [189, 396, 423, 436]}]], ["block_8", [" 6.4 \u2022 Electronic Structure of Atoms (Electron Configurations) \n 291 \n"]]], "page_305": [["block_0", [" 292 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", ["Beginning with the transition metal scandium (atomic number 21), additional electrons are added\nsuccessively to the 3d subshell. This subshell is filled to its capacity with 10 electrons (remember that for l = 2\n[d orbitals], there are 2l + 1 = 5 values of ml, meaning that there are five d orbitals that have a combined\ncapacity of 10 electrons). The 4p subshell fills next. Note that for three series of elements, scandium (Sc)\nthrough copper (Cu), yttrium (Y) through silver (Ag), and lutetium (Lu) through gold (Au), a total of 10 d\nelectrons are successively added to the (n \u2013 1) shell next to the n shell to bring that (n \u2013 1) shell from 8 to 18\nelectrons. For two series, lanthanum (La) through lutetium (Lu) and actinium (Ac) through lawrencium (Lr), 14\nf electrons (l = 3, 2l + 1 = 7 ml values; thus, seven orbitals with a combined capacity of 14 electrons) are\nsuccessively added to the (n \u2013 2) shell to bring that shell from 18 electrons to a total of 32 electrons.\n"]], ["block_2", [{"image_0": "305_0.png", "coords": [72, 57, 540, 423]}]], ["block_3", [" FIGURE 6.29 \nThis version of the periodic table shows the outer-shell electron configuration of each element. Note\n"]], ["block_4", ["that down each group, the configuration is often similar.\n"]], ["block_5", ["When we come to the next element in the periodic table, the alkali metal potassium (atomic number 19), we\nmight expect that we would begin to add electrons to the 3d subshell. However, all available chemical and\nphysical evidence indicates that potassium is like lithium and sodium, and that the next electron is not added\nto the 3d level but is, instead, added to the 4s level (Figure 6.29). As discussed previously, the 3d orbital with no\nradial nodes is higher in energy because it is less penetrating and more shielded from the nucleus than the 4s,\nwhich has three radial nodes. Thus, potassium has an electron configuration of [Ar]4s. Hence, potassium\ncorresponds to Li and Na in its valence shell configuration. The next electron is added to complete the 4s\nsubshell and calcium has an electron configuration of [Ar]4s. This gives calcium an outer-shell electron\nconfiguration corresponding to that of beryllium and magnesium.\n"]], ["block_6", [" Access for free at openstax.org \n"]]], "page_306": [["block_0", [" Quantum Numbers and Electron Configurations \n"]], ["block_1", ["What is the electron configuration and orbital diagram for a phosphorus atom? What are the four quantum\nnumbers for the last electron added?\n"]], ["block_2", [" Solution \n"]], ["block_3", ["The atomic number of phosphorus is 15. Thus, a phosphorus atom contains 15 electrons. The order of filling of\nthe energy levels is 1s, 2s, 2p, 3s, 3p, 4s, . . . The 15 electrons of the phosphorus atom will fill up to the 3p\norbital, which will contain three electrons:\n"]], ["block_4", [{"image_0": "306_0.png", "coords": [72, 197, 432, 238]}]], ["block_5", ["The last electron added is a 3p electron. Therefore, n = 3 and, for a p-type orbital, l = 1. The ml value could be\n\u20131, 0, or +1. The three p orbitals are degenerate, so any of these ml values is correct. For unpaired electrons,\nconvention assigns the value of\nfor the spin quantum number; thus,\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["Identify the atoms from the electron configurations given:\n"]], ["block_8", ["(a) [Ar]4s3d\n"]], ["block_9", ["(b) [Kr]5s4d5p\n"]], ["block_10", [" Answer: \n(a) Mn (b) Xe\n"]], ["block_11", ["The periodic table can be a powerful tool in predicting the electron configuration of an element. However, we\ndo find exceptions to the order of filling of orbitals that are shown in Figure 6.26 or Figure 6.27. For instance,\nthe electron configurations (shown in Figure 6.29) of the transition metals chromium (Cr; atomic number 24)\nand copper (Cu; atomic number 29), among others, are not those we would expect. In general, such exceptions\ninvolve subshells with very similar energy, and small effects can lead to changes in the order of filling.\n"]], ["block_12", ["In the case of Cr and Cu, we find that half-filled and completely filled subshells apparently represent conditions\nof preferred stability. This stability is such that an electron shifts from the 4s into the 3d orbital to gain the\nextra stability of a half-filled 3d subshell (in Cr) or a filled 3d subshell (in Cu). Other exceptions also occur. For\nexample, niobium (Nb, atomic number 41) is predicted to have the electron configuration [Kr]5s4d.\nExperimentally, we observe that its ground-state electron configuration is actually [Kr]5s4d. We can\nrationalize this observation by saying that the electron\u2013electron repulsions experienced by pairing the\nelectrons in the 5s orbital are larger than the gap in energy between the 5s and 4d orbitals. There is no simple\nmethod to predict the exceptions for atoms where the magnitude of the repulsions between electrons is\ngreater than the small differences in energy between subshells.\n"]], ["block_13", [" Electron Configurations and the Periodic Table \n"]], ["block_14", ["As described earlier, the periodic table arranges atoms based on increasing atomic number so that elements\nwith the same chemical properties recur periodically. When their electron configurations are added to the\ntable (Figure 6.29), we also see a periodic recurrence of similar electron configurations in the outer shells of\nthese elements. Because they are in the outer shells of an atom, valence electrons play the most important role\nin chemical reactions. The outer electrons have the highest energy of the electrons in an atom and are more\neasily lost or shared than the core electrons. Valence electrons are also the determining factor in some\nphysical properties of the elements.\n"]], ["block_15", ["Elements in any one group (or column) have the same number of valence electrons; the alkali metals lithium\n"]], ["block_16", ["EXAMPLE 6.10\n"]], ["block_17", [" 6.4 \u2022 Electronic Structure of Atoms (Electron Configurations) \n 293 \n"]]], "page_307": [["block_0", [" 294 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", ["Ions are formed when atoms gain or lose electrons. A cation (positively charged ion) forms when one or more\nelectrons are removed from a parent atom. For main group elements, the electrons that were added last are\nthe first electrons removed. For transition metals and inner transition metals, however, electrons in the\ns orbital are easier to remove than the d or f electrons, and so the highest ns electrons are lost, and then the\n(n \u2013 1)d or (n \u2013 2)f electrons are removed. An anion (negatively charged ion) forms when one or more\nelectrons are added to a parent atom. The added electrons fill in the order predicted by the Aufbau principle.\n"]], ["block_2", ["and sodium each have only one valence electron, the alkaline earth metals beryllium and magnesium each\nhave two, and the halogens fluorine and chlorine each have seven valence electrons. The similarity in chemical\nproperties among elements of the same group occurs because they have the same number of valence\nelectrons. It is the loss, gain, or sharing of valence electrons that defines how elements react.\n"]], ["block_3", ["It is important to remember that the periodic table was developed on the basis of the chemical behavior of the\nelements, well before any idea of their atomic structure was available. Now we can understand why the\nperiodic table has the arrangement it has\u2014the arrangement puts elements whose atoms have the same\nnumber of valence electrons in the same group. This arrangement is emphasized in Figure 6.29, which shows\nin periodic-table form the electron configuration of the last subshell to be filled by the Aufbau principle. The\ncolored sections of Figure 6.29 show the three categories of elements classified by the orbitals being filled:\nmain group, transition, and inner transition elements. These classifications determine which orbitals are\ncounted in the valence shell , or highest energy level orbitals of an atom.\n"]], ["block_4", ["Lanthanum and actinium, because of their similarities to the other members of the series, are included and\nused to name the series, even though they are transition metals with no f electrons.\n"]], ["block_5", [" Electron Configurations of Ions \n"]], ["block_6", [" Predicting Electron Configurations of Ions \n"]], ["block_7", ["What is the electron configuration of:\n"]], ["block_8", ["(a) Na\n"]], ["block_9", ["(b) P\n"]], ["block_10", ["(c) Al\n"]], ["block_11", ["(d) Fe\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["1.\n Main group elements (sometimes called representative elements ) are those in which the last electron\nadded enters an s or a p orbital in the outermost shell, shown in blue and red in Figure 6.29. This category\nincludes all the nonmetallic elements, as well as many metals and the metalloids. The valence electrons\nfor main group elements are those with the highest n level. For example, gallium (Ga, atomic number 31)\nhas the electron configuration [Ar]4s3d4p, which contains three valence electrons (underlined). The\ncompletely filled d orbitals count as core, not valence, electrons.\n"]], ["block_14", ["2.\n Transition elements or transition metals . These are metallic elements in which the last electron added\nenters a d orbital. The valence electrons (those added after the last noble gas configuration) in these\nelements include the ns and (n \u2013 1) d electrons. The official IUPAC definition of transition elements\nspecifies those with partially filled d orbitals. Thus, the elements with completely filled orbitals (Zn, Cd,\nHg, as well as Cu, Ag, and Au in Figure 6.29) are not technically transition elements. However, the term is\nfrequently used to refer to the entire d block (colored yellow in Figure 6.29), and we will adopt this usage in\nthis textbook.\n"]], ["block_15", ["3.\n Inner transition elements are metallic elements in which the last electron added occupies an f orbital.\nThey are shown in green in Figure 6.29. The valence shells of the inner transition elements consist of the\n(n \u2013 2)f, the (n \u2013 1)d, and the ns subshells. There are two inner transition series:\n"]], ["block_16", ["b.\nThe actinide series: actinium (Ac) through lawrencium (Lr)\n"]], ["block_17", ["a.\nThe lanthanide series: lanthanum (La) through lutetium (Lu)\n"]], ["block_18", ["EXAMPLE 6.11\n"]]], "page_308": [["block_0", ["(e) Sm\n"]], ["block_1", [" Solution \n"]], ["block_2", ["First, write out the electron configuration for each parent atom. We have chosen to show the full,\nunabbreviated configurations to provide more practice for students who want it, but listing the core-\nabbreviated electron configurations is also acceptable.\n"]], ["block_3", ["Next, determine whether an electron is gained or lost. Remember electrons are negatively charged, so ions\nwith a positive charge have lost an electron. For main group elements, the last orbital gains or loses the\nelectron. For transition metals, the last s orbital loses an electron before the d orbitals.\n"]], ["block_4", ["(a) Na: 1s2s2p3s. Sodium cation loses one electron, so Na: 1s2s2p3s= Na: 1s2s2p.\n"]], ["block_5", ["(b) P: 1s2s2p3s3p. Phosphorus trianion gains three electrons, so P: 1s2s2p3s3p.\n"]], ["block_6", ["(c) Al: 1s2s2p3s3p. Aluminum dication loses two electrons Al: 1s2s2p3s3p=\n"]], ["block_7", ["Al: 1s2s2p3s.\n"]], ["block_8", ["(d) Fe: 1s2s2p3s3p4s3d. Iron(II) loses two electrons and, since it is a transition metal, they are removed\nfrom the 4s orbital Fe: 1s2s2p3s3p4s3d= 1s2s2p3s3p3d.\n"]], ["block_9", ["(e). Sm: 1s2s2p3s3p4s3d4p5s4d5p6s4f. Samarium trication loses three electrons. The first two\nwill be lost from the 6s orbital, and the final one is removed from the 4f orbital. Sm:\n1s2s2p3s3p4s3d4p5s4d5p6s4f= 1s2s2p3s3p4s3d4p5s4d5p4f.\n"]], ["block_10", [" Check Your Learning \n"]], ["block_11", ["Which ion with a +2 charge has the electron configuration 1s2s2p3s3p4s3d4p4d? Which ion with a\n+3 charge has this configuration?\n"]], ["block_12", [" Answer: \nTc, Ru\n"]], ["block_13", [" 6.5 Periodic Variations in Element Properties \n"]], ["block_14", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_15", ["The elements in groups (vertical columns) of the periodic table exhibit similar chemical behavior. This\nsimilarity occurs because the members of a group have the same number and distribution of electrons in their\nvalence shells. However, there are also other patterns in chemical properties on the periodic table. For\nexample, as we move down a group, the metallic character of the atoms increases. Oxygen, at the top of group\n16 (6A), is a colorless gas; in the middle of the group, selenium is a semiconducting solid; and, toward the\nbottom, polonium is a silver-grey solid that conducts electricity.\n"]], ["block_16", ["As we go across a period from left to right, we add a proton to the nucleus and an electron to the valence shell\nwith each successive element. As we go down the elements in a group, the number of electrons in the valence\nshell remains constant, but the principal quantum number increases by one each time. An understanding of\nthe electronic structure of the elements allows us to examine some of the properties that govern their chemical\nbehavior. These properties vary periodically as the electronic structure of the elements changes. They are (1)\nsize (radius) of atoms and ions, (2) ionization energies, and (3) electron affinities.\n"]], ["block_17", ["Explore visualizations (http://openstax.org/l/16pertrends) of the periodic trends discussed in this section (and\nmany more trends). With just a few clicks, you can create three-dimensional versions of the periodic table\nshowing atomic size or graphs of ionization energies from all measured elements.\n"]], ["block_18", ["\u2022\nDescribe and explain the observed trends in atomic size, ionization energy, and electron affinity of the elements\n"]], ["block_19", ["LINK TO LEARNING\n"]], ["block_20", [" 6.5 \u2022 Periodic Variations in Element Properties \n 295 \n"]]], "page_309": [["block_0", [" 296 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", [" Variation in Covalent Radius \n"]], ["block_2", ["The quantum mechanical picture makes it difficult to establish a definite size of an atom. However, there are\nseveral practical ways to define the radius of atoms and, thus, to determine their relative sizes that give roughly\nsimilar values. We will use the covalent radius (Figure 6.30), which is defined as one-half the distance between\nthe nuclei of two identical atoms when they are joined by a covalent bond (this measurement is possible\nbecause atoms within molecules still retain much of their atomic identity). We know that as we scan down a\ngroup, the principal quantum number, n, increases by one for each element. Thus, the electrons are being\nadded to a region of space that is increasingly distant from the nucleus. Consequently, the size of the atom (and\nits covalent radius) must increase as we increase the distance of the outermost electrons from the nucleus.\nThis trend is illustrated for the covalent radii of the halogens in Table 6.2 and Figure 6.30. The trends for the\nentire periodic table can be seen in Figure 6.30.\n"]], ["block_3", [" Access for free at openstax.org \n"]], ["block_4", [" TABLE 6.2 \n"]], ["block_5", [" Atom \n Covalent radius (pm) \n Nuclear charge \n"]], ["block_6", ["F\n64\n+9\n"]], ["block_7", ["Cl\n99\n+17\n"]], ["block_8", ["Br\n114\n+35\n"]], ["block_9", ["I\n133\n+53\n"]], ["block_10", ["At\n148\n+85\n"]], ["block_11", ["Covalent Radii of the Halogen Group Elements\n"]]], "page_310": [["block_0", [{"image_0": "310_0.png", "coords": [72, 57, 540, 435]}]], ["block_1", [" FIGURE 6.30 \n(a) The radius of an atom is defined as one-half the distance between the nuclei in a molecule\n"]], ["block_2", ["consisting of two identical atoms joined by a covalent bond. The atomic radius for the halogens increases down the\ngroup as n increases. (b) Covalent radii of the elements are shown to scale. The general trend is that radii increase\ndown a group and decrease across a period.\n"]], ["block_3", [" 6.5 \u2022 Periodic Variations in Element Properties \n 297 \n"]]], "page_311": [["block_0", [" 298 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", [{"image_0": "311_0.png", "coords": [72, 57, 540, 401]}]], ["block_2", [" FIGURE 6.31 \nWithin each period, the trend in atomic radius decreases as Z increases; for example, from K to Kr.\n"]], ["block_3", ["Within each group (e.g., the alkali metals shown in purple), the trend is that atomic radius increases as Z increases.\n"]], ["block_4", ["As shown in Figure 6.31, as we move across a period from left to right, we generally find that each element has\na smaller covalent radius than the element preceding it. This might seem counterintuitive because it implies\nthat atoms with more electrons have a smaller atomic radius. This can be explained with the concept of\n effective nuclear charge, Z eff . This is the pull exerted on a specific electron by the nucleus, taking into\naccount any electron\u2013electron repulsions. For hydrogen, there is only one electron and so the nuclear charge\n(Z) and the effective nuclear charge (Zeff) are equal. For all other atoms, the inner electrons partially shield the\nouter electrons from the pull of the nucleus, and thus:\n"]], ["block_5", ["Shielding is determined by the probability of another electron being between the electron of interest and the\nnucleus, as well as by the electron\u2013electron repulsions the electron of interest encounters. Core electrons are\nadept at shielding, while electrons in the same valence shell do not block the nuclear attraction experienced by\neach other as efficiently. Thus, each time we move from one element to the next across a period, Z increases by\none, but the shielding increases only slightly. Thus, Zeff increases as we move from left to right across a period.\nThe stronger pull (higher effective nuclear charge) experienced by electrons on the right side of the periodic\ntable draws them closer to the nucleus, making the covalent radii smaller.\n"]], ["block_6", ["Thus, as we would expect, the outermost or valence electrons are easiest to remove because they have the\nhighest energies, are shielded more, and are farthest from the nucleus. As a general rule, when the\nrepresentative elements form cations, they do so by the loss of the ns or np electrons that were added last in\nthe Aufbau process. The transition elements, on the other hand, lose the ns electrons before they begin to lose\nthe (n \u2013 1)d electrons, even though the ns electrons are added first, according to the Aufbau principle.\n"]], ["block_7", [" Access for free at openstax.org \n"]]], "page_312": [["block_0", [" Sorting Atomic Radii \n"]], ["block_1", ["Predict the order of increasing covalent radius for Ge, Fl, Br, Kr.\n"]], ["block_2", [" Solution \n"]], ["block_3", ["Radius increases as we move down a group, so Ge < Fl (Note: Fl is the symbol for flerovium, element 114, NOT\nfluorine). Radius decreases as we move across a period, so Kr < Br < Ge. Putting the trends together, we obtain\nKr < Br < Ge < Fl.\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["Give an example of an atom whose size is smaller than fluorine.\n"]], ["block_6", [" Answer: \nNe or He\n"]], ["block_7", [" Variation in Ionic Radii \n"]], ["block_8", ["Ionic radius is the measure used to describe the size of an ion. A cation always has fewer electrons and the\nsame number of protons as the parent atom; it is smaller than the atom from which it is derived (Figure 6.32).\nFor example, the covalent radius of an aluminum atom (1s2s2p3s3p) is 118 pm, whereas the ionic radius\nof an Al(1s2s2p) is 68 pm. As electrons are removed from the outer valence shell, the remaining core\nelectrons occupying smaller shells experience a greater effective nuclear charge Zeff (as discussed) and are\ndrawn even closer to the nucleus.\n"]], ["block_9", [" FIGURE 6.32 \nThe radius for a cation is smaller than the parent atom (Al), due to the lost electrons; the radius for\n"]], ["block_10", ["an anion is larger than the parent (S), due to the gained electrons.\n"]], ["block_11", ["Cations with larger charges are smaller than cations with smaller charges (e.g., Vhas an ionic radius of 79\npm, while that of Vis 64 pm). Proceeding down the groups of the periodic table, we find that cations of\nsuccessive elements with the same charge generally have larger radii, corresponding to an increase in the\nprincipal quantum number, n.\n"]], ["block_12", ["An anion (negative ion) is formed by the addition of one or more electrons to the valence shell of an atom. This\nresults in a greater repulsion among the electrons and a decrease in Zeff per electron. Both effects (the\nincreased number of electrons and the decreased Zeff) cause the radius of an anion to be larger than that of the\nparent atom (Figure 6.32). For example, a sulfur atom ([Ne]3s3p) has a covalent radius of 104 pm, whereas\nthe ionic radius of the sulfide anion ([Ne]3s3p) is 170 pm. For consecutive elements proceeding down any\ngroup, anions have larger principal quantum numbers and, thus, larger radii.\n"]], ["block_13", ["Atoms and ions that have the same electron configuration are said to be isoelectronic . Examples of\nisoelectronic species are N, O, F, Ne, Na, Mg, and Al(1s2s2p). Another isoelectronic series is P,\nS, Cl, Ar, K, Ca, and Sc([Ne]3s3p). For atoms or ions that are isoelectronic, the number of protons\ndetermines the size. The greater the nuclear charge, the smaller the radius in a series of isoelectronic ions and\natoms.\n"]], ["block_14", [" Variation in Ionization Energies \n"]], ["block_15", ["The amount of energy required to remove the most loosely bound electron from a gaseous atom in its ground\nstate is called its first ionization energy (IE1). The first ionization energy for an element, X, is the energy\nrequired to form a cation with +1 charge:\n"]], ["block_16", ["EXAMPLE 6.12\n"]], ["block_17", [{"image_0": "312_0.png", "coords": [189, 368, 423, 401]}]], ["block_18", [" 6.5 \u2022 Periodic Variations in Element Properties \n 299 \n"]]], "page_313": [["block_0", [" 300 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", ["The energy required to remove the second most loosely bound electron is called the second ionization energy\n(IE2).\n"]], ["block_2", ["The energy required to remove the third electron is the third ionization energy, and so on. Energy is always\nrequired to remove electrons from atoms or ions, so ionization processes are endothermic and IE values are\nalways positive. For larger atoms, the most loosely bound electron is located farther from the nucleus and so is\neasier to remove. Thus, as size (atomic radius) increases, the ionization energy should decrease. Relating this\nlogic to what we have just learned about radii, we would expect first ionization energies to decrease down a\ngroup and to increase across a period.\n"]], ["block_3", ["Figure 6.33 graphs the relationship between the first ionization energy and the atomic number of several\nelements. The values of first ionization energy for the elements are given in Figure 6.34. Within a period, the\nIE1 generally increases with increasing Z. Down a group, the IE1 value generally decreases with increasing Z.\nThere are some systematic deviations from this trend, however. Note that the ionization energy of boron\n(atomic number 5) is less than that of beryllium (atomic number 4) even though the nuclear charge of boron is\ngreater by one proton. This can be explained because the energy of the subshells increases as l increases, due\nto penetration and shielding (as discussed previously in this chapter). Within any one shell, the s electrons are\nlower in energy than the p electrons. This means that an s electron is harder to remove from an atom than a p\nelectron in the same shell. The electron removed during the ionization of beryllium ([He]2s) is an s electron,\nwhereas the electron removed during the ionization of boron ([He]2s2p) is a p electron; this results in a lower\nfirst ionization energy for boron, even though its nuclear charge is greater by one proton. Thus, we see a small\ndeviation from the predicted trend occurring each time a new subshell begins.\n"]], ["block_4", [{"image_0": "313_0.png", "coords": [72, 347, 540, 678]}]], ["block_5", [" FIGURE 6.33 \nThe first ionization energy of the elements in the first five periods are plotted against their atomic\n"]], ["block_6", ["number.\n"]], ["block_7", [" Access for free at openstax.org \n"]]], "page_314": [["block_0", [{"image_0": "314_0.png", "coords": [72, 57, 540, 283]}]], ["block_1", [" FIGURE 6.34 \nThis version of the periodic table shows the first ionization energy (IE1), in kJ/mol, of selected\n"]], ["block_2", ["elements.\n"]], ["block_3", ["Another deviation occurs as orbitals become more than one-half filled. The first ionization energy for oxygen is\nslightly less than that for nitrogen, despite the trend in increasing IE1 values across a period. Looking at the\norbital diagram of oxygen, we can see that removing one electron will eliminate the electron\u2013electron\nrepulsion caused by pairing the electrons in the 2p orbital and will result in a half-filled orbital (which is\nenergetically favorable). Analogous changes occur in succeeding periods (note the dip for sulfur after\nphosphorus in Figure 6.34).\n"]], ["block_4", [{"image_1": "314_1.png", "coords": [72, 399, 306, 440]}]], ["block_5", ["Removing an electron from a cation is more difficult than removing an electron from a neutral atom because of\nthe greater electrostatic attraction to the cation. Likewise, removing an electron from a cation with a higher\npositive charge is more difficult than removing an electron from an ion with a lower charge. Thus, successive\nionization energies for one element always increase. As seen in Table 6.3, there is a large increase in the\nionization energies for each element. This jump corresponds to removal of the core electrons, which are\nharder to remove than the valence electrons. For example, Sc and Ga both have three valence electrons, so the\nrapid increase in ionization energy occurs after the third ionization.\n"]], ["block_6", [" TABLE 6.3 \n"]], ["block_7", [" Element \n IE 1 \n IE 2 \n IE 3 \n IE 4 \n IE 5 \n IE 6 \n IE 7 \n"]], ["block_8", ["K\n418.8\n3051.8\n4419.6\n5876.9\n7975.5\n9590.6\n11343\n"]], ["block_9", ["Ca\n589.8\n1145.4\n4912.4\n6490.6\n8153.0\n10495.7\n12272.9\n"]], ["block_10", ["Sc\n633.1\n1235.0\n2388.7\n7090.6\n8842.9\n10679.0\n13315.0\n"]], ["block_11", ["Ga\n578.8\n1979.4\n2964.6\n6180\n8298.7\n10873.9\n13594.8\n"]], ["block_12", ["Successive Ionization Energies for Selected Elements (kJ/mol)\n"]], ["block_13", [" 6.5 \u2022 Periodic Variations in Element Properties \n 301 \n"]]], "page_315": [["block_0", [" 302 \n 6 \u2022 Electronic Structure and Periodic Properties of Elements \n"]], ["block_1", [" Ranking Ionization Energies \n"]], ["block_2", ["Predict the order of increasing energy for the following processes: IE1 for Al, IE1 for Tl, IE2 for Na, IE3 for Al.\n"]], ["block_3", [" Solution \n"]], ["block_4", ["Removing the 6pelectron from Tl is easier than removing the 3pelectron from Al because the higher n\norbital is farther from the nucleus, so IE1(Tl) < IE1(Al). Ionizing the third electron from\n"]], ["block_5", ["electron than the neutral Al atom, so IE1(Al) < IE3(Al). The second ionization energy for sodium removes a core\nelectron, which is a much higher energy process than removing valence electrons. Putting this all together, we\nobtain: IE1(Tl) < IE1(Al) < IE3(Al) < IE2(Na).\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["Which has the lowest value for IE1: O, Po, Pb, or Ba?\n"]], ["block_8", [" Answer: \nBa\n"]], ["block_9", [" Variation in Electron Affinities \n"]], ["block_10", ["The electron affinity (EA) is the energy change for the process of adding an electron to a gaseous atom to form\nan anion (negative ion).\n"]], ["block_11", ["This process can be either endothermic or exothermic, depending on the element. The EA of some of the\nelements is given in Figure 6.35. You can see that many of these elements have negative values of EA, which\nmeans that energy is released when the gaseous atom accepts an electron. However, for some elements,\nenergy is required for the atom to become negatively charged and the value of their EA is positive. Just as with\nionization energy, subsequent EA values are associated with forming ions with more charge. The second EA is\nthe energy associated with adding an electron to an anion to form a \u20132 ion, and so on.\n"]], ["block_12", ["As we might predict, it becomes easier to add an electron across a series of atoms as the effective nuclear\ncharge of the atoms increases. We find, as we go from left to right across a period, EAs tend to become more\nnegative. The exceptions found among the elements of group 2 (2A), group 15 (5A), and group 18 (8A) can be\nunderstood based on the electronic structure of these groups. The noble gases, group 18 (8A), have a\ncompletely filled shell and the incoming electron must be added to a higher n level, which is more difficult to\ndo. Group 2 (2A) has a filled ns subshell, and so the next electron added goes into the higher energy np, so,\nagain, the observed EA value is not as the trend would predict. Finally, group 15 (5A) has a half-filled np\nsubshell and the next electron must be paired with an existing np electron. In all of these cases, the initial\nrelative stability of the electron configuration disrupts the trend in EA.\n"]], ["block_13", ["We also might expect the atom at the top of each group to have the most negative EA; their first ionization\npotentials suggest that these atoms have the largest effective nuclear charges. However, as we move down a\ngroup, we see that the second element in the group most often has the most negative EA. This can be attributed\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["EXAMPLE 6.13\n"]], ["block_16", [" TABLE 6.3 \n"]], ["block_17", [" Element \n IE 1 \n IE 2 \n IE 3 \n IE 4 \n IE 5 \n IE 6 \n IE 7 \n"]], ["block_18", ["Ge\n762.2\n1537.5\n3302.1\n4410.6\n9021.4\nNot available\nNot available\n"]], ["block_19", ["As\n944.5\n1793.6\n2735.5\n4836.8\n6042.9\n12311.5\nNot available\n"]], ["block_20", ["requires more energy because the cation Alexerts a stronger pull on the\n"]]], "page_316": [["block_0", ["to the small size of the n = 2 shell and the resulting large electron\u2013electron repulsions. For example, chlorine,\nwith an EA value of \u2013348 kJ/mol, has the highest value of any element in the periodic table. The EA of fluorine\nis \u2013322 kJ/mol. When we add an electron to a fluorine atom to form a fluoride anion (F), we add an electron to\nthe n = 2 shell. The electron is attracted to the nucleus, but there is also significant repulsion from the other\nelectrons already present in this small valence shell. The chlorine atom has the same electron configuration in\nthe valence shell, but because the entering electron is going into the n = 3 shell, it occupies a considerably\nlarger region of space and the electron\u2013electron repulsions are reduced. The entering electron does not\nexperience as much repulsion and the chlorine atom accepts an additional electron more readily, resulting in a\nmore negative EA.\n"]], ["block_1", [{"image_0": "316_0.png", "coords": [72, 177, 540, 410]}]], ["block_2", [" FIGURE 6.35 \nThis version of the periodic table displays the electron affinity values (in kJ/mol) for selected\n"]], ["block_3", ["elements.\n"]], ["block_4", ["The properties discussed in this section (size of atoms and ions, effective nuclear charge, ionization energies,\nand electron affinities) are central to understanding chemical reactivity. For example, because fluorine has an\nenergetically favorable EA and a large energy barrier to ionization (IE), it is much easier to form fluorine\nanions than cations. Metallic properties including conductivity and malleability (the ability to be formed into\nsheets) depend on having electrons that can be removed easily. Thus, metallic character increases as we move\ndown a group and decreases across a period in the same trend observed for atomic size because it is easier to\nremove an electron that is farther away from the nucleus.\n"]], ["block_5", [" 6.5 \u2022 Periodic Variations in Element Properties \n 303 \n"]]], "page_317": [["block_0", [" d orbital \nregion of space with high electron density\n"]], ["block_1", [" 304 \n 6 \u2022 Key Terms \n"]], ["block_2", [" Key Terms \n"]], ["block_3", ["amplitude\nextent of the displacement caused by a\n"]], ["block_4", [" atomic orbital \nmathematical function that\n"]], ["block_5", [" Aufbau principle \nprocedure in which the electron\n"]], ["block_6", [" blackbody \nidealized perfect absorber of all\n"]], ["block_7", [" Bohr\u2019s model of the hydrogen atom \nstructural\n"]], ["block_8", [" continuous spectrum \n electromagnetic radiation \n"]], ["block_9", [" core electron \nelectron in an atom that occupies the\n"]], ["block_10", [" covalent radius \none-half the distance between the\n"]], ["block_11", [" degenerate orbitals \norbitals that have the same\n"]], ["block_12", [" effective nuclear charge \ncharge that leads to the\n"]], ["block_13", [" electromagnetic radiation \nenergy transmitted by\n"]], ["block_14", [" electromagnetic spectrum \nrange of energies that\n"]], ["block_15", [" electron affinity \nenergy change associated with\n"]], ["block_16", [" electron configuration \nlisting that identifies the\n"]], ["block_17", [" electron density \na measure of the probability of\n"]], ["block_18", [" excited state \nstate having an energy greater than\n"]], ["block_19", [" Access for free at openstax.org \n"]], ["block_20", ["wave\n"]], ["block_21", ["describes the behavior of an electron in an atom\n(also called the wavefunction)\n"]], ["block_22", ["configuration of the elements is determined by\n\u201cbuilding\u201d them in order of atomic numbers,\nadding one proton to the nucleus and one\nelectron to the proper subshell at a time\n"]], ["block_23", ["incident electromagnetic radiation; such bodies\nemit electromagnetic radiation in characteristic\ncontinuous spectra called blackbody radiation\n"]], ["block_24", ["model in which an electron moves around the\nnucleus only in circular orbits, each with a\nspecific allowed radius\n"]], ["block_25", ["given off in an unbroken series of wavelengths\n(e.g., white light from the sun)\n"]], ["block_26", ["orbitals of the inner shells\n"]], ["block_27", ["nuclei of two identical atoms when they are\njoined by a covalent bond\n"]], ["block_28", ["that is either four lobed or contains a dumbbell\nand torus shape; describes orbitals with l = 2.\n"]], ["block_29", ["energy\n"]], ["block_30", ["Coulomb force exerted by the nucleus on an\nelectron, calculated as the nuclear charge minus\nshielding\n"]], ["block_31", ["waves that have an electric-field component and a\nmagnetic-field component\n"]], ["block_32", ["electromagnetic radiation can comprise,\nincluding radio, microwaves, infrared, visible,\nultraviolet, X-rays, and gamma rays\n"]], ["block_33", ["addition of an electron to a gaseous atom or ion\n"]], ["block_34", ["electron occupancy of an atom\u2019s shells and\nsubshells\n"]], ["block_35", ["locating an electron in a particular region of\nspace, it is equal to the squared absolute value of\nthe wave function \u03c8\n"]], ["block_36", [" f orbital \nmultilobed region of space with high\n"]], ["block_37", [" p orbital \ndumbbell-shaped region of space with\n"]], ["block_38", [" frequency ( \u03bd ) \nnumber of wave cycles (peaks or\n"]], ["block_39", [" ground state \nstate in which the electrons in an\n"]], ["block_40", [" Heisenberg uncertainty principle \nrule stating\n"]], ["block_41", [" hertz (Hz) \nthe unit of frequency, which is the\n"]], ["block_42", [" Hund\u2019s rule \nevery orbital in a subshell is singly\n"]], ["block_43", [" intensity \nproperty of wave-propagated energy\n"]], ["block_44", [" interference pattern \npattern typically consisting\n"]], ["block_45", [" ionization energy \nenergy required to remove an\n"]], ["block_46", [" isoelectronic \ngroup of ions or atoms that have\n"]], ["block_47", [" line spectrum \nelectromagnetic radiation emitted\n"]], ["block_48", [" magnetic quantum number (m l ) \nquantum\n"]], ["block_49", [" node \nany point of a standing wave with zero\n"]], ["block_50", [" orbital diagram \npictorial representation of the\n"]], ["block_51", [" Pauli exclusion principle \nspecifies that no two\n"]], ["block_52", [" photon \nsmallest possible packet of\n"]], ["block_53", [" principal quantum number (n) \nquantum number\n"]], ["block_54", ["the ground-state energy\n"]], ["block_55", ["electron density, describes orbitals with l = 3\n"]], ["block_56", ["troughs) that pass a specified point in space per\nunit time\n"]], ["block_57", ["atom, ion, or molecule have the lowest energy\npossible\n"]], ["block_58", ["that it is impossible to exactly determine both\ncertain conjugate dynamical properties such as\nthe momentum and the position of a particle at\nthe same time. The uncertainty principle is a\nconsequence of quantum particles exhibiting\nwave\u2013particle duality\n"]], ["block_59", ["number of cycles per second, s\n"]], ["block_60", ["occupied with one electron before any one orbital\nis doubly occupied, and all electrons in singly\noccupied orbitals have the same spin\n"]], ["block_61", ["related to the amplitude of the wave, such as\nbrightness of light or loudness of sound\n"]], ["block_62", ["of alternating bright and dark fringes; it results\nfrom constructive and destructive interference of\nwaves\n"]], ["block_63", ["electron from a gaseous atom or ion\n"]], ["block_64", ["identical electron configurations\n"]], ["block_65", ["at discrete wavelengths by a specific atom (or\natoms) in an excited state\n"]], ["block_66", ["number signifying the orientation of an atomic\norbital around the nucleus\n"]], ["block_67", ["amplitude\n"]], ["block_68", ["electron configuration showing each orbital as a\nbox and each electron as an arrow\n"]], ["block_69", ["high electron density, describes orbitals with l = 1\n"]], ["block_70", ["electrons in an atom can have the same value for\nall four quantum numbers\n"]], ["block_71", ["electromagnetic radiation, a particle of light\n"]]], "page_318": [["block_0", [" s orbital \nspherical region of space with high\n"]], ["block_1", ["behavior, which can be characterized by a frequency,\n\u03bd, and a wavelength, \u03bb, such that c = \u03bb\u03bd. Light is an\nexample of a travelling wave. Other important wave\nphenomena include standing waves, periodic\noscillations, and vibrations. Standing waves exhibit\nquantization, since their wavelengths are limited to\ndiscrete integer multiples of some characteristic\nlengths. Electromagnetic radiation that passes\nthrough two closely spaced narrow slits having\ndimensions roughly similar to the wavelength will\nshow an interference pattern that is a result of\n"]], ["block_2", [" quantization \nlimitation of some property to\n"]], ["block_3", [" quantum mechanics \nfield of study that includes\n"]], ["block_4", [" quantum number \nnumber having only specific\n"]], ["block_5", [" secondary (angular momentum) quantum \n"]], ["block_6", [" shell \natomic orbitals with the same principal\n"]], ["block_7", [" spin quantum number (m s ) \nnumber specifying\n"]], ["block_8", [" standing wave \n(also, stationary wave) localized\n"]], ["block_9", [" Key Equations \n"]], ["block_10", [" Summary \n"]], ["block_11", [" 6.1 Electromagnetic Energy \n"]], ["block_12", ["Light and other forms of electromagnetic radiation\nmove through a vacuum with a constant speed, c, of\n2.998\n10m s. This radiation shows wavelike\n"]], ["block_13", ["c = \u03bb\u03bd\n"]], ["block_14", ["specifying the shell an electron occupies in an\natom\n"]], ["block_15", ["specific discrete values, not continuous\n"]], ["block_16", ["quantization of energy, wave-particle duality, and\nthe Heisenberg uncertainty principle to describe\nmatter\n"]], ["block_17", ["allowed values and used to characterize the\narrangement of electrons in an atom\n"]], ["block_18", ["electron density, describes orbitals with l = 0\n"]], ["block_19", [" number (l) \nquantum number distinguishing the\n"]], ["block_20", ["different shapes of orbitals; it is also a measure of\nthe orbital angular momentum\n"]], ["block_21", ["quantum number, n\n"]], ["block_22", ["the electron spin direction, either\nor\n"]], ["block_23", ["\u221e\n"]], ["block_24", ["where h = 6.626\n10J s\n"]], ["block_25", [" subshell \natomic orbitals with the same values of n\n"]], ["block_26", [" valence electrons \nelectrons in the high energy\n"]], ["block_27", [" valence shell \nhigh energy outer shell(s) of an atom\n"]], ["block_28", [" wave \noscillation of a property over time or space;\n"]], ["block_29", [" wave-particle duality \nobservation that elementary\n"]], ["block_30", [" wavefunction ( \u03c8 ) \nmathematical description of an\n"]], ["block_31", [" wavelength ( \u03bb ) \ndistance between two consecutive\n"]], ["block_32", ["constructive and destructive interference of the\nwaves. Electromagnetic radiation also demonstrates\nproperties of particles called photons. The energy of\na photon is related to the frequency (or alternatively,\nthe wavelength) of the radiation as E = h\u03bd (or\n"]], ["block_33", ["demonstrates both wavelike and particle-like\nbehavior is known as wave-particle duality. All forms\nof electromagnetic radiation share these properties,\nalthough various forms including X-rays, visible\nlight, microwaves, and radio waves interact\ndifferently with matter and have very different\npractical applications. Electromagnetic radiation\ncan be generated by exciting matter to higher\nenergies, such as by heating it. The emitted light can\n"]], ["block_34", ["wave phenomenon characterized by discrete\nwavelengths determined by the boundary\nconditions used to generate the waves; standing\nwaves are inherently quantized\n"]], ["block_35", ["and l\n"]], ["block_36", ["outer shell(s) of an atom\n"]], ["block_37", ["can transport energy from one point to another\n"]], ["block_38", ["particles can exhibit both wave-like and particle-\nlike properties\n"]], ["block_39", ["atomic orbital that describes the shape of the\norbital; it can be used to calculate the probability\nof finding the electron at any given location in the\norbital, as well as dynamical variables such as the\nenergy and the angular momentum\n"]], ["block_40", ["peaks or troughs in a wave\n"]], ["block_41", ["), where h is Planck's constant. That light\n"]], ["block_42", [" 6 \u2022 Key Equations \n 305 \n"]]], "page_319": [["block_0", [" 306 \n 6 \u2022 Summary \n"]], ["block_1", ["be either continuous (incandescent sources like the\nsun) or discrete (from specific types of excited\natoms). Continuous spectra often have distributions\nthat can be approximated as blackbody radiation at\nsome appropriate temperature. The line spectrum of\nhydrogen can be obtained by passing the light from\nan electrified tube of hydrogen gas through a prism.\nThis line spectrum was simple enough that an\nempirical formula called the Rydberg formula could\nbe derived from the spectrum. Three historically\nimportant paradoxes from the late 19th and early\n20th centuries that could not be explained within\nthe existing framework of classical mechanics and\nclassical electromagnetism were the blackbody\nproblem, the photoelectric effect, and the discrete\nspectra of atoms. The resolution of these paradoxes\nultimately led to quantum theories that superseded\nthe classical theories.\n"]], ["block_2", [" 6.2 The Bohr Model \n"]], ["block_3", ["Bohr incorporated Planck\u2019s and Einstein\u2019s\nquantization ideas into a model of the hydrogen\natom that resolved the paradox of atom stability and\ndiscrete spectra. The Bohr model of the hydrogen\natom explains the connection between the\nquantization of photons and the quantized emission\nfrom atoms. Bohr described the hydrogen atom in\nterms of an electron moving in a circular orbit about\na nucleus. He postulated that the electron was\nrestricted to certain orbits characterized by discrete\nenergies. Transitions between these allowed orbits\nresult in the absorption or emission of photons.\nWhen an electron moves from a higher-energy orbit\nto a more stable one, energy is emitted in the form of\na photon. To move an electron from a stable orbit to\na more excited one, a photon of energy must be\nabsorbed. Using the Bohr model, we can calculate\nthe energy of an electron and the radius of its orbit\nin any one-electron system.\n"]], ["block_4", [" 6.3 Development of Quantum Theory \n"]], ["block_5", ["Macroscopic objects act as particles. Microscopic\nobjects (such as electrons) have properties of both a\nparticle and a wave. Their exact trajectories cannot\nbe determined. The quantum mechanical model of\natoms describes the three-dimensional position of\nthe electron in a probabilistic manner according to a\nmathematical function called a wavefunction, often\ndenoted as \u03c8. Atomic wavefunctions are also called\norbitals. The squared magnitude of the wavefunction\ndescribes the distribution of the probability of\nfinding the electron in a particular region in space.\nTherefore, atomic orbitals describe the areas in an\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", ["atom where electrons are most likely to be found.\n"]], ["block_8", ["An atomic orbital is characterized by three quantum\nnumbers. The principal quantum number, n, can be\nany positive integer. The general region for value of\nenergy of the orbital and the average distance of an\nelectron from the nucleus are related to n. Orbitals\nhaving the same value of n are said to be in the same\nshell. The secondary (angular momentum) quantum\nnumber, l, can have any integer value from 0 to n \u2013 1.\nThis quantum number describes the shape or type\nof the orbital. Orbitals with the same principal\nquantum number and the same l value belong to the\nsame subshell. The magnetic quantum number, ml,\nwith 2l + 1 values ranging from \u2013l to +l, describes the\norientation of the orbital in space. In addition, each\nelectron has a spin quantum number, ms, that can\nbe equal to\nNo two electrons in the same atom\n"]], ["block_9", ["can have the same set of values for all the four\nquantum numbers.\n"]], ["block_10", [" 6.4 Electronic Structure of Atoms (Electron \n Configurations) \n"]], ["block_11", ["The relative energy of the subshells determine the\norder in which atomic orbitals are filled (1s, 2s, 2p,\n3s, 3p, 4s, 3d, 4p, and so on). Electron configurations\nand orbital diagrams can be determined by applying\nthe Pauli exclusion principle (no two electrons can\nhave the same set of four quantum numbers) and\nHund\u2019s rule (whenever possible, electrons retain\nunpaired spins in degenerate orbitals).\n"]], ["block_12", ["Electrons in the outermost orbitals, called valence\nelectrons, are responsible for most of the chemical\nbehavior of elements. In the periodic table, elements\nwith analogous valence electron configurations\nusually occur within the same group. There are\nsome exceptions to the predicted filling order,\nparticularly when half-filled or completely filled\norbitals can be formed. The periodic table can be\ndivided into three categories based on the orbital in\nwhich the last electron to be added is placed: main\ngroup elements (s and p orbitals), transition\nelements (d orbitals), and inner transition elements\n(f orbitals).\n"]], ["block_13", [" 6.5 Periodic Variations in Element \n Properties \n"]], ["block_14", ["Electron configurations allow us to understand\nmany periodic trends. Covalent radius increases as\nwe move down a group because the n level (orbital\nsize) increases. Covalent radius mostly decreases as\nwe move left to right across a period because the\neffective nuclear charge experienced by the\n"]]], "page_320": [["block_0", ["electrons increases, and the electrons are pulled in\ntighter to the nucleus. Anionic radii are larger than\nthe parent atom, while cationic radii are smaller,\nbecause the number of valence electrons has\nchanged while the nuclear charge has remained\nconstant. Ionization energy (the energy associated\nwith forming a cation) decreases down a group and\nmostly increases across a period because it is easier\nto remove an electron from a larger, higher energy\norbital. Electron affinity (the energy associated with\n"]], ["block_1", [" Exercises \n"]], ["block_2", [" 6.1 Electromagnetic Energy \n"]], ["block_3", [" 10 . Photons of infrared radiation are responsible for much of the warmth we feel when holding our hands\n"]], ["block_4", [" 11 . One of the radiographic devices used in a dentist's office emits an X-ray of wavelength 2.090\n10m.\n"]], ["block_5", [" 12 . The eyes of certain reptiles pass a single visual signal to the brain when the visual receptors are struck by\n"]], ["block_6", [" 13 . RGB color television and computer displays use cathode ray tubes that produce colors by mixing red,\n"]], ["block_7", [" 1 . The light produced by a red neon sign is due to the emission of light by excited neon atoms. Qualitatively\n"]], ["block_8", [" 2 . An FM radio station found at 103.1 on the FM dial broadcasts at a frequency of 1.031\n10s(103.1\n"]], ["block_9", [" 3 . FM-95, an FM radio station, broadcasts at a frequency of 9.51\n10s(95.1 MHz). What is the wavelength\n"]], ["block_10", [" 4 . A bright violet line occurs at 435.8 nm in the emission spectrum of mercury vapor. What amount of\n"]], ["block_11", [" 5 . Light with a wavelength of 614.5 nm looks orange. What is the energy, in joules, per photon of this orange\n"]], ["block_12", [" 6 . Heated lithium atoms emit photons of light with an energy of 2.961\n10J. Calculate the frequency and\n"]], ["block_13", [" 7 . A photon of light produced by a surgical laser has an energy of 3.027\n10J. Calculate the frequency and\n"]], ["block_14", [" 8 . When rubidium ions are heated to a high temperature, two lines are observed in its line spectrum at\n"]], ["block_15", [" 9 . The emission spectrum of cesium contains two lines whose frequencies are (a) 3.45\n10Hz and (b) 6.53\n"]], ["block_16", ["describe the spectrum produced by passing light from a neon lamp through a prism.\n"]], ["block_17", ["MHz). What is the wavelength of these radio waves in meters?\n"]], ["block_18", ["of these radio waves in meters?\n"]], ["block_19", ["energy, in joules, must be released by an electron in a mercury atom to produce a photon of this light?\n"]], ["block_20", ["light? What is the energy in eV (1 eV = 1.602\n10J)?\n"]], ["block_21", ["wavelength of one of these photons. What is the total energy in 1 mole of these photons? What is the color\nof the emitted light?\n"]], ["block_22", ["wavelength of the photon. What is the total energy in 1 mole of photons? What is the color of the emitted\nlight?\n"]], ["block_23", ["wavelengths (a) 7.9\n10m and (b) 4.2\n10m. What are the frequencies of the two lines? What color do\n"]], ["block_24", ["we see when we heat a rubidium compound?\n"]], ["block_25", ["before a fire. These photons will also warm other objects. How many infrared photons with a wavelength of\n1.5\n10m must be absorbed by the water to warm a cup of water (175 g) from 25.0 \u00b0C to 40 \u00b0C?\n"]], ["block_26", ["What is the energy, in joules, and frequency of this X-ray?\n"]], ["block_27", ["photons of a wavelength of 850 nm. If a total energy of 3.15\n10J is required to trip the signal, what is\n"]], ["block_28", ["the minimum number of photons that must strike the receptor?\n"]], ["block_29", ["green, and blue light. If we look at the screen with a magnifying glass, we can see individual dots turn on\nand off as the colors change. Using a spectrum of visible light, determine the approximate wavelength of\neach of these colors. What is the frequency and energy of a photon of each of these colors?\n"]], ["block_30", ["10Hz. What are the wavelengths and energies per photon of the two lines? What color are the lines?\n"]], ["block_31", ["forming an anion) is more favorable (exothermic)\nwhen electrons are placed into lower energy orbitals,\ncloser to the nucleus. Therefore, electron affinity\nbecomes increasingly negative as we move left to\nright across the periodic table and decreases as we\nmove down a group. For both IE and electron affinity\ndata, there are exceptions to the trends when\ndealing with completely filled or half-filled\nsubshells.\n"]], ["block_32", [" 6 \u2022 Exercises \n 307 \n"]]], "page_321": [["block_0", [" 308 \n 6 \u2022 Exercises \n"]], ["block_1", [" 14 . Answer the following questions about a Blu-ray laser:\n"]], ["block_2", [" 15 . What is the threshold frequency for sodium metal if a photon with frequency 6.66\n10sejects an\n"]], ["block_3", [" 6.2 The Bohr Model \n"]], ["block_4", [" 16 . Why is the electron in a Bohr hydrogen atom bound less tightly when it has a quantum number of 3 than\n"]], ["block_5", [" 17 . What does it mean to say that the energy of the electrons in an atom is quantized?\n 18 . Using the Bohr model, determine the energy, in joules, necessary to ionize a ground-state hydrogen atom.\n"]], ["block_6", [" 19 . The electron volt (eV) is a convenient unit of energy for expressing atomic-scale energies. It is the amount\n"]], ["block_7", [" 20 . Using the Bohr model, determine the lowest possible energy, in joules, for the electron in the Liion.\n 21 . Using the Bohr model, determine the lowest possible energy for the electron in the Heion.\n 22 . Using the Bohr model, determine the energy of an electron with n = 6 in a hydrogen atom.\n 23 . Using the Bohr model, determine the energy of an electron with n = 8 in a hydrogen atom.\n 24 . How far from the nucleus in angstroms (1 angstrom = 1\n10m) is the electron in a hydrogen atom if it\n"]], ["block_8", [" 25 . What is the radius, in angstroms, of the orbital of an electron with n = 8 in a hydrogen atom?\n 26 . Using the Bohr model, determine the energy in joules of the photon produced when an electron in a He\n"]], ["block_9", [" 27 . Using the Bohr model, determine the energy in joules of the photon produced when an electron in a Li\n"]], ["block_10", [" 28 . Consider a large number of hydrogen atoms with electrons randomly distributed in the n = 1, 2, 3, and 4\n"]], ["block_11", [" 29 . How are the Bohr model and the Rutherford model of the atom similar? How are they different?\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["(a) The laser on a Blu-ray player has a wavelength of 405 nm. In what region of the electromagnetic\nspectrum is this radiation? What is its frequency?\n(b) A Blu-ray laser has a power of 5 milliwatts (1 watt = 1 J s). How many photons of light are produced by\nthe laser in 1 hour?\n(c) The ideal resolution of a player using a laser (such as a Blu-ray player), which determines how close\ntogether data can be stored on a compact disk, is determined using the following formula: Resolution =\n0.60(\u03bb/NA), where \u03bb is the wavelength of the laser and NA is the numerical aperture. Numerical aperture\nis a measure of the size of the spot of light on the disk; the larger the NA, the smaller the spot. In a typical\nBlu-ray system, NA = 0.95. If the 405-nm laser is used in a Blu-ray player, what is the closest that\ninformation can be stored on a Blu-ray disk?\n(d) The data density of a Blu-ray disk using a 405-nm laser is 1.5\n10bits mm. Disks have an outside\n"]], ["block_14", ["diameter of 120 mm and a hole of 15-mm diameter. How many data bits can be contained on the disk? If a\nBlu-ray disk can hold 9,400,000 pages of text, how many data bits are needed for a typed page? (Hint:\nDetermine the area of the disk that is available to hold data. The area inside a circle is given by A = \u03c0r,\nwhere the radius r is one-half of the diameter.)\n"]], ["block_15", ["electron with 7.74\n10J kinetic energy? Will the photoelectric effect be observed if sodium is exposed\n"]], ["block_16", ["to orange light?\n"]], ["block_17", ["when it has a quantum number of 1?\n"]], ["block_18", ["Show your calculations.\n"]], ["block_19", ["of energy that an electron gains when subjected to a potential of 1 volt; 1 eV = 1.602\n10J. Using the\n"]], ["block_20", ["Bohr model, determine the energy, in electron volts, of the photon produced when an electron in a\nhydrogen atom moves from the orbit with n = 5 to the orbit with n = 2. Show your calculations.\n"]], ["block_21", ["has an energy of \u20138.72\n10J?\n"]], ["block_22", ["ion moves from the orbit with n = 5 to the orbit with n = 2.\n"]], ["block_23", ["ion moves from the orbit with n = 2 to the orbit with n = 1.\n"]], ["block_24", ["orbits.\n(a) How many different wavelengths of light are emitted by these atoms as the electrons fall into lower-\nenergy orbits?\n(b) Calculate the lowest and highest energies of light produced by the transitions described in part (a).\n(c) Calculate the frequencies and wavelengths of the light produced by the transitions described in part\n(b).\n"]]], "page_322": [["block_0", [" 30 . The spectra of hydrogen and of calcium are shown here.\n"]], ["block_1", [" 6.3 Development of Quantum Theory \n"]], ["block_2", [" 31 . How are the Bohr model and the quantum mechanical model of the hydrogen atom similar? How are they\n"]], ["block_3", [" 32 . What are the allowed values for each of the four quantum numbers: n, l, ml, and ms?\n 33 . Describe the properties of an electron associated with each of the following four quantum numbers: n, l,\n"]], ["block_4", [" 34 . Answer the following questions:\n"]], ["block_5", [" 35 . Identify the subshell in which electrons with the following quantum numbers are found:\n"]], ["block_6", [" 36 . Which of the subshells described in the previous question contain degenerate orbitals? How many\n"]], ["block_7", [" 37 . Identify the subshell in which electrons with the following quantum numbers are found:\n"]], ["block_8", [" 38 . Which of the subshells described in the previous question contain degenerate orbitals? How many\n"]], ["block_9", [" 39 . Sketch the boundary surface of a\nand a py orbital. Be sure to show and label the axes.\n"]], ["block_10", [" 40 . Sketch the px and dxz orbitals. Be sure to show and label the coordinates.\n"]], ["block_11", ["ml, and ms.\n"]], ["block_12", [{"image_0": "322_0.png", "coords": [91, 70, 537, 378]}]], ["block_13", ["What causes the lines in these spectra? Why are the colors of the lines different? Suggest a reason for the\nobservation that the spectrum of calcium is more complicated than the spectrum of hydrogen.\n"]], ["block_14", ["different?\n"]], ["block_15", ["(a) Without using quantum numbers, describe the differences between the shells, subshells, and orbitals\nof an atom.\n(b) How do the quantum numbers of the shells, subshells, and orbitals of an atom differ?\n"]], ["block_16", ["(a) n = 2, l = 1\n(b) n = 4, l = 2\n(c) n = 6, l = 0\n"]], ["block_17", ["degenerate orbitals are in each?\n"]], ["block_18", ["(a) n = 3, l = 2\n(b) n = 1, l = 0\n(c) n = 4, l = 3\n"]], ["block_19", ["degenerate orbitals are in each?\n"]], ["block_20", [" 6 \u2022 Exercises \n 309 \n"]]], "page_323": [["block_0", [" 310 \n 6 \u2022 Exercises \n"]], ["block_1", [" 41 . Consider the orbitals shown here in outline.\n"]], ["block_2", [" 42 . State the Heisenberg uncertainty principle. Describe briefly what the principle implies.\n 43 . How many electrons could be held in the second shell of an atom if the spin quantum number ms could\n"]], ["block_3", [" 44 . Which of the following equations describe particle-like behavior? Which describe wavelike behavior? Do\n"]], ["block_4", [" 45 . Write a set of quantum numbers for each of the electrons with an n of 4 in a Se atom.\n"]], ["block_5", [" 6.4 Electronic Structure of Atoms (Electron Configurations) \n"]], ["block_6", [" 46 . Read the labels of several commercial products and identify monatomic ions of at least four transition\n"]], ["block_7", [" 47 . Read the labels of several commercial products and identify monatomic ions of at least six main group\n"]], ["block_8", [" 48 . Using complete subshell notation (not abbreviations, 1s2s2p, and so forth), predict the electron\n"]], ["block_9", [" 49 . Using complete subshell notation (1s2s2p, and so forth), predict the electron configuration of each of\n"]], ["block_10", [" 50 . Is 1s2s2pthe symbol for a macroscopic property or a microscopic property of an element? Explain\n"]], ["block_11", [" 51 . What additional information do we need to answer the question \u201cWhich ion has the electron configuration\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", [{"image_0": "323_0.png", "coords": [91, 70, 325, 146]}]], ["block_14", ["(a) What is the maximum number of electrons contained in an orbital of type (x)? Of type (y)? Of type (z)?\n(b) How many orbitals of type (x) are found in a shell with n = 2? How many of type (y)? How many of type\n(z)?\n(c) Write a set of quantum numbers for an electron in an orbital of type (x) in a shell with n = 4. Of an\norbital of type (y) in a shell with n = 2. Of an orbital of type (z) in a shell with n = 3.\n(d) What is the smallest possible n value for an orbital of type (x)? Of type (y)? Of type (z)?\n(e) What are the possible l and ml values for an orbital of type (x)? Of type (y)? Of type (z)?\n"]], ["block_15", ["have three values instead of just two? (Hint: Consider the Pauli exclusion principle.)\n"]], ["block_16", ["any involve both types of behavior? Describe the reasons for your choices.\n(a) c = \u03bb\u03bd\n"]], ["block_17", ["(b)\n"]], ["block_18", ["(c)\n"]], ["block_19", ["(d) E = h\u03bd\n(e)\n"]], ["block_20", ["elements contained in the products. Write the complete electron configurations of these cations.\n"]], ["block_21", ["elements contained in the products. Write the complete electron configurations of these cations and\nanions.\n"]], ["block_22", ["configuration of each of the following atoms:\n(a) C\n(b) P\n(c) V\n(d) Sb\n(e) Sm\n"]], ["block_23", ["the following atoms:\n(a) N\n(b) Si\n(c) Fe\n(d) Te\n(e) Tb\n"]], ["block_24", ["your answer.\n"]], ["block_25", ["1s2s2p3s3p\u201d?\n"]]], "page_324": [["block_0", [" 52 . Draw the orbital diagram for the valence shell of each of the following atoms:\n"]], ["block_1", [" 53 . Use an orbital diagram to describe the electron configuration of the valence shell of each of the following\n"]], ["block_2", [" 54 . Using complete subshell notation (1s2s2p, and so forth), predict the electron configurations of the\n"]], ["block_3", [" 55 . Which atom has the electron configuration 1s2s2p3s3p4s3d4p5s4d?\n 56 . Which atom has the electron configuration 1s2s2p3s3p3d4s?\n 57 . Which ion with a +1 charge has the electron configuration 1s2s2p3s3p3d4s4p? Which ion with a\n"]], ["block_4", [" 58 . Which of the following atoms contains only three valence electrons: Li, B, N, F, Ne?\n 59 . Which of the following has two unpaired electrons?\n"]], ["block_5", [" 60 . Which atom would be expected to have a half-filled 6p subshell?\n 61 . Which atom would be expected to have a half-filled 4s subshell?\n 62 . In one area of Australia, the cattle did not thrive despite the presence of suitable forage. An investigation\n"]], ["block_6", [" 63 . Thallium was used as a poison in the Agatha Christie mystery story \u201cThe Pale Horse.\u201d Thallium has two\n"]], ["block_7", [" 64 . Write the electron configurations for the following atoms or ions:\n"]], ["block_8", [" 65 . Cobalt\u201360 and iodine\u2013131 are radioactive isotopes commonly used in nuclear medicine. How many\n"]], ["block_9", [" 66 . Write a set of quantum numbers for each of the electrons with an n of 3 in a Sc atom.\n"]], ["block_10", ["(a) C\n(b) P\n(c) V\n(d) Sb\n(e) Ru\n"]], ["block_11", ["atoms:\n(a) N\n(b) Si\n(c) Fe\n(d) Te\n(e) Mo\n"]], ["block_12", ["following ions.\n(a) N\n"]], ["block_13", ["(b) Ca\n"]], ["block_14", ["(c) S\n"]], ["block_15", ["(d) Cs\n"]], ["block_16", ["(e) Cr\n"]], ["block_17", ["(f) Gd\n"]], ["block_18", ["\u20132 charge has this configuration?\n"]], ["block_19", ["(a) Mg\n(b) Si\n(c) S\n(d) Both Mg and S\n(e) Both Si and S.\n"]], ["block_20", ["showed the cause to be the absence of sufficient cobalt in the soil. Cobalt forms cations in two oxidation\nstates, Coand Co. Write the electron structure of the two cations.\n"]], ["block_21", ["possible cationic forms, +1 and +3. The +1 compounds are the more stable. Write the electron structure of\nthe +1 cation of thallium.\n"]], ["block_22", ["(a) B\n"]], ["block_23", ["(b) O\n"]], ["block_24", ["(c) Cl\n"]], ["block_25", ["(d) Ca\n"]], ["block_26", ["(e) Ti\n"]], ["block_27", ["protons, neutrons, and electrons are in atoms of these isotopes? Write the complete electron configuration\nfor each isotope.\n"]], ["block_28", [" 6 \u2022 Exercises \n 311 \n"]]], "page_325": [["block_0", [" 312 \n 6 \u2022 Exercises \n"]], ["block_1", [" 6.5 Periodic Variations in Element Properties \n"]], ["block_2", [" 67 . Based on their positions in the periodic table, predict which has the smallest atomic radius: Mg, Sr, Si, Cl,\n"]], ["block_3", [" 68 . Based on their positions in the periodic table, predict which has the largest atomic radius: Li, Rb, N, F, I.\n 69 . Based on their positions in the periodic table, predict which has the largest first ionization energy: Mg, Ba,\n"]], ["block_4", [" 70 . Based on their positions in the periodic table, predict which has the smallest first ionization energy: Li, Cs,\n"]], ["block_5", [" 71 . Based on their positions in the periodic table, rank the following atoms in order of increasing first\n"]], ["block_6", [" 72 . Based on their positions in the periodic table, rank the following atoms in order of increasing first\n"]], ["block_7", [" 73 . Atoms of which group in the periodic table have a valence shell electron configuration of nsnp?\n 74 . Atoms of which group in the periodic table have a valence shell electron configuration of ns?\n 75 . Based on their positions in the periodic table, list the following atoms in order of increasing radius: Mg,\n"]], ["block_8", [" 76 . Based on their positions in the periodic table, list the following atoms in order of increasing radius: Sr, Ca,\n"]], ["block_9", [" 77 . Based on their positions in the periodic table, list the following ions in order of increasing radius: K, Ca,\n"]], ["block_10", [" 78 . List the following ions in order of increasing radius: Li, Mg, Br, Te.\n 79 . Which atom and/or ion is (are) isoelectronic with Br: Se, Se, As, Kr, Ga, Cl?\n 80 . Which of the following atoms and ions is (are) isoelectronic with S: Si, Cl, Ar, As, Si, Al?\n 81 . Compare both the numbers of protons and electrons present in each to rank the following ions in order of\n"]], ["block_11", [" 82 . Of the five elements Al, Cl, I, Na, Rb, which has the most exothermic reaction? (E represents an atom.)\n"]], ["block_12", [" 83 . Of the five elements Sn, Si, Sb, O, Te, which has the most endothermic reaction? (E represents an atom.)\n"]], ["block_13", [" 84 . The ionic radii of the ions S, Cl, and Kare 184, 181, 138 pm respectively. Explain why these ions have\n"]], ["block_14", [" 85 . Which main group atom would be expected to have the lowest second ionization energy?\n 86 . Explain why Al is a member of group 13 rather than group 3?\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["I.\n"]], ["block_17", ["B, O, Te.\n"]], ["block_18", ["N, F, I.\n"]], ["block_19", ["ionization energy: F, Li, N, Rb\n"]], ["block_20", ["ionization energy: Mg, O, S, Si\n"]], ["block_21", ["Ca, Rb, Cs.\n"]], ["block_22", ["Si, Cl.\n"]], ["block_23", ["Al, Si.\n"]], ["block_24", ["increasing radius: As, Br, K, Mg.\n"]], ["block_25", ["What name is given to the energy for the reaction? Hint: Note the process depicted does not correspond to\nelectron affinity.)\n"]], ["block_26", ["What name is given to the energy for the reaction?\n"]], ["block_27", ["different sizes even though they contain the same number of electrons.\n"]]], "page_326": [["block_0", ["CHAPTER 7\nChemical Bonding and Molecular\nGeometry\n"]], ["block_1", [{"image_0": "326_0.png", "coords": [72, 131, 622, 316]}]], ["block_2", [" Figure 7.1 \nNicknamed \u201cbuckyballs,\u201d buckminsterfullerene molecules (C60) contain only carbon atoms (left)\n"]], ["block_3", ["arranged to form a geometric framework of hexagons and pentagons, similar to the pattern on a soccer ball (center).\nThis molecular structure is named after architect R. Buckminster Fuller, whose innovative designs combined simple\ngeometric shapes to create large, strong structures such as this weather radar dome near Tucson, Arizona (right).\n(credit middle: modification of work by \u201cPetey21\u201d/Wikimedia Commons; credit right: modification of work by Bill\nMorrow)\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 7.1 Ionic Bonding \n 7.2 Covalent Bonding \n 7.3 Lewis Symbols and Structures \n 7.4 Formal Charges and Resonance \n"]], ["block_6", [" 7.5 Strengths of Ionic and Covalent Bonds \n 7.6 Molecular Structure and Polarity \n"]], ["block_7", [" INTRODUCTION \n"]], ["block_8", ["graphite and diamonds. But it was not until 1985 that a new form of carbon was recognized:\nbuckminsterfullerene. This molecule was named after the architect and inventor R. Buckminster Fuller\n(1895\u20131983), whose signature architectural design was the geodesic dome, characterized by a lattice shell\nstructure supporting a spherical surface. Experimental evidence revealed the formula, C60, and then scientists\ndetermined how 60 carbon atoms could form one symmetric, stable molecule. They were guided by bonding\ntheory\u2014the topic of this chapter\u2014which explains how individual atoms connect to form more complex\nstructures.\n"]], ["block_9", [" 7.1 Ionic Bonding \n"]], ["block_10", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_11", ["\u2022\nExplain the formation of cations, anions, and ionic compounds\n"]], ["block_12", ["\u2022\nPredict the charge of common metallic and nonmetallic elements, and write their electron configurations\n"]], ["block_13", ["It has long been known that pure carbon occurs in different forms (allotropes) including\n"]]], "page_327": [["block_0", [" 314 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", ["Neutral atoms and their associated ions have very different physical and chemical properties. Sodium atoms\nform sodium metal, a soft, silvery-white metal that burns vigorously in air and reacts explosively with water.\nChlorine atoms form chlorine gas, Cl2, a yellow-green gas that is extremely corrosive to most metals and very\npoisonous to animals and plants. The vigorous reaction between the elements sodium and chlorine forms the\nwhite, crystalline compound sodium chloride, common table salt, which contains sodium cations and chloride\nanions (Figure 7.2). The compound composed of these ions exhibits properties entirely different from the\nproperties of the elements sodium and chlorine. Chlorine is poisonous, but sodium chloride is essential to life;\nsodium atoms react vigorously with water, but sodium chloride simply dissolves in water.\n"]], ["block_2", ["As you have learned, ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms\nwhen a neutral atom loses one or more electrons from its valence shell, and an anion (a negative ion) forms\nwhen a neutral atom gains one or more electrons in its valence shell.\n"]], ["block_3", ["Compounds composed of ions are called ionic compounds (or salts), and their constituent ions are held\ntogether by ionic bonds : electrostatic forces of attraction between oppositely charged cations and anions. The\nproperties of ionic compounds shed some light on the nature of ionic bonds. Ionic solids exhibit a crystalline\nstructure and tend to be rigid and brittle; they also tend to have high melting and boiling points, which\nsuggests that ionic bonds are very strong. Ionic solids are also poor conductors of electricity for the same\nreason\u2014the strength of ionic bonds prevents ions from moving freely in the solid state. Most ionic solids,\nhowever, dissolve readily in water. Once dissolved or melted, ionic compounds are excellent conductors of\nelectricity and heat because the ions can move about freely.\n"]], ["block_4", [{"image_0": "327_0.png", "coords": [72, 315, 540, 472]}]], ["block_5", [" FIGURE 7.2 \n(a) Sodium is a soft metal that must be stored in mineral oil to prevent reaction with air or water. (b)\n"]], ["block_6", ["Chlorine is a pale yellow-green gas. (c) When combined, they form white crystals of sodium chloride (table salt).\n(credit a: modification of work by \u201cJurii\u201d/Wikimedia Commons)\n"]], ["block_7", [" The Formation of Ionic Compounds \n"]], ["block_8", ["Binary ionic compounds are composed of just two elements: a metal (which forms the cations) and a nonmetal\n(which forms the anions). For example, NaCl is a binary ionic compound. We can think about the formation of\nsuch compounds in terms of the periodic properties of the elements. Many metallic elements have relatively\nlow ionization potentials and lose electrons easily. These elements lie to the left in a period or near the bottom\nof a group on the periodic table. Nonmetal atoms have relatively high electron affinities and thus readily gain\nelectrons lost by metal atoms, thereby filling their valence shells. Nonmetallic elements are found in the\nupper-right corner of the periodic table.\n"]], ["block_9", ["As all substances must be electrically neutral, the total number of positive charges on the cations of an ionic\ncompound must equal the total number of negative charges on its anions. The formula of an ionic compound\nrepresents the simplest ratio of the numbers of ions necessary to give identical numbers of positive and\nnegative charges. For example, the formula for aluminum oxide, Al2O3, indicates that this ionic compound\ncontains two aluminum cations, Al, for every three oxide anions, O[thus, (2\n+3) + (3\n\u20132) = 0].\n"]], ["block_10", ["It is important to note, however, that the formula for an ionic compound does not represent the physical\narrangement of its ions. It is incorrect to refer to a sodium chloride (NaCl) \u201cmolecule\u201d because there is not a\n"]], ["block_11", [" Access for free at openstax.org \n"]]], "page_328": [["block_0", ["single ionic bond, per se, between any specific pair of sodium and chloride ions. The attractive forces between\nions are isotropic\u2014the same in all directions\u2014meaning that any particular ion is equally attracted to all of the\nnearby ions of opposite charge. This results in the ions arranging themselves into a tightly bound, three-\ndimensional lattice structure. Sodium chloride, for example, consists of a regular arrangement of equal\nnumbers of Nacations and Clanions (Figure 7.3).\n"]], ["block_1", [" FIGURE 7.3 \nThe atoms in sodium chloride (common table salt) are arranged to (a) maximize opposite charges\n"]], ["block_2", ["interacting. The smaller spheres represent sodium ions, the larger ones represent chloride ions. In the expanded\nview (b), the geometry can be seen more clearly. Note that each ion is \u201cbonded\u201d to all of the surrounding ions\u2014six in\nthis case.\n"]], ["block_3", ["The strong electrostatic attraction between Naand Clions holds them tightly together in solid NaCl. It\nrequires 769 kJ of energy to dissociate one mole of solid NaCl into separate gaseous Naand Clions:\n"]], ["block_4", [" Electronic Structures of Cations \n"]], ["block_5", ["When forming a cation, an atom of a main group element tends to lose all of its valence electrons, thus\nassuming the electronic structure of the noble gas that precedes it in the periodic table. For groups 1 (the alkali\nmetals) and 2 (the alkaline earth metals), the group numbers are equal to the numbers of valence shell\nelectrons and, consequently, to the charges of the cations formed from atoms of these elements when all\nvalence shell electrons are removed. For example, calcium is a group 2 element whose neutral atoms have 20\nelectrons and a ground state electron configuration of 1s2s2p3s3p4s. When a Ca atom loses both of its\nvalence electrons, the result is a cation with 18 electrons, a 2+ charge, and an electron configuration of\n1s2s2p3s3p. The Caion is therefore isoelectronic with the noble gas Ar.\n"]], ["block_6", ["For groups 13\u201317, the group numbers exceed the number of valence electrons by 10 (accounting for the\npossibility of full d subshells in atoms of elements in the fourth and greater periods). Thus, the charge of a\ncation formed by the loss of all valence electrons is equal to the group number minus 10. For example,\naluminum (in group 13) forms 3+ ions (Al).\n"]], ["block_7", ["Exceptions to the expected behavior involve elements toward the bottom of the groups. In addition to the\nexpected ions Tl, Sn, Pb, and Bi, a partial loss of these atoms\u2019 valence shell electrons can also lead to\nthe formation of Tl, Sn, Pb, and Biions. The formation of these 1+, 2+, and 3+ cations is ascribed to the\n inert pair effect , which reflects the relatively low energy of the valence s-electron pair for atoms of the heavy\nelements of groups 13, 14, and 15. Mercury (group 12) also exhibits an unexpected behavior: it forms a\ndiatomic ion,\n(an ion formed from two mercury atoms, with an Hg-Hg bond), in addition to the expected\n"]], ["block_8", ["monatomic ion Hg(formed from only one mercury atom).\n"]], ["block_9", ["Transition and inner transition metal elements behave differently than main group elements. Most transition\nmetal cations have 2+ or 3+ charges that result from the loss of their outermost s electron(s) first, sometimes\nfollowed by the loss of one or two d electrons from the next-to-outermost shell. For example, iron\n(1s2s2p3s3p3d4s) forms the ion Fe(1s2s2p3s3p3d) by the loss of the 4s electrons and the ion\nFe(1s2s2p3s3p3d) by the loss of the 4s electrons and one of the 3d electrons. Although the d orbitals of\n"]], ["block_10", [{"image_0": "328_0.png", "coords": [189, 126, 423, 277]}]], ["block_11", [" 7.1 \u2022 Ionic Bonding \n 315 \n"]]], "page_329": [["block_0", [" 316 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", ["Most monatomic anions form when a neutral nonmetal atom gains enough electrons to completely fill its outer\ns and p orbitals, thereby reaching the electron configuration of the next noble gas. Thus, it is simple to\ndetermine the charge on such a negative ion: The charge is equal to the number of electrons that must be\ngained to fill the s and p orbitals of the parent atom. Oxygen, for example, has the electron configuration\n1s2s2p, whereas the oxygen anion has the electron configuration of the noble gas neon (Ne), 1s2s2p. The\ntwo additional electrons required to fill the valence orbitals give the oxide ion the charge of 2\u2013 (O).\n"]], ["block_2", ["the transition elements are\u2014according to the Aufbau principle\u2014the last to fill when building up electron\nconfigurations, the outermost s electrons are the first to be lost when these atoms ionize. When the inner\ntransition metals form ions, they usually have a 3+ charge, resulting from the loss of their outermost s\nelectrons and a d or f electron.\n"]], ["block_3", [" Determining the Electronic Structures of Cations \n"]], ["block_4", ["There are at least 14 elements categorized as \u201cessential trace elements\u201d for the human body. They are called\n\u201cessential\u201d because they are required for healthy bodily functions, \u201ctrace\u201d because they are required only in\nsmall amounts, and \u201celements\u201d in spite of the fact that they are really ions. Two of these essential trace\nelements, chromium and zinc, are required as Crand Zn. Write the electron configurations of these\ncations.\n"]], ["block_5", [" Solution \n"]], ["block_6", ["First, write the electron configuration for the neutral atoms:\n"]], ["block_7", ["Zn: [Ar]3d4s\n"]], ["block_8", ["Cr: [Ar]3d4s\n"]], ["block_9", ["Next, remove electrons from the highest energy orbital. For the transition metals, electrons are removed from\nthe s orbital first and then from the d orbital. For the p-block elements, electrons are removed from the p\norbitals and then from the s orbital. Zinc is a member of group 12, so it should have a charge of 2+, and thus\nloses only the two electrons in its s orbital. Chromium is a transition element and should lose its s electrons\nand then its d electrons when forming a cation. Thus, we find the following electron configurations of the ions:\n"]], ["block_10", ["Zn: [Ar]3d\n"]], ["block_11", ["Cr: [Ar]3d\n"]], ["block_12", [" Check Your Learning \n"]], ["block_13", ["Potassium and magnesium are required in our diet. Write the electron configurations of the ions expected\nfrom these elements.\n"]], ["block_14", [" Answer: \nK: [Ar], Mg: [Ne]\n"]], ["block_15", [" Electronic Structures of Anions \n"]], ["block_16", [" Determining the Electronic Structure of Anions \n"]], ["block_17", ["Selenium and iodine are two essential trace elements that form anions. Write the electron configurations of the\nanions.\n"]], ["block_18", [" Solution \n"]], ["block_19", ["Se: [Ar]3d4s4p\n"]], ["block_20", [" Access for free at openstax.org \n"]], ["block_21", ["EXAMPLE 7.1\n"]], ["block_22", ["EXAMPLE 7.2\n"]]], "page_330": [["block_0", ["I: [Kr]4d5s5p\n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["Write the electron configurations of a phosphorus atom and its negative ion. Give the charge on the anion.\n"]], ["block_3", [" Answer: \nP: [Ne]3s3p; P: [Ne]3s3p\n"]], ["block_4", [" 7.2 Covalent Bonding \n"]], ["block_5", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_6", ["Ionic bonding results from the electrostatic attraction of oppositely charged ions that are typically produced by\nthe transfer of electrons between metallic and nonmetallic atoms. A different type of bonding results from the\nmutual attraction of atoms for a \u201cshared\u201d pair of electrons. Such bonds are called covalent bonds . Covalent\nbonds are formed between two atoms when both have similar tendencies to attract electrons to themselves\n(i.e., when both atoms have identical or fairly similar ionization energies and electron affinities). For example,\ntwo hydrogen atoms bond covalently to form an H2 molecule; each hydrogen atom in the H2 molecule has two\nelectrons stabilizing it, giving each atom the same number of valence electrons as the noble gas He.\n"]], ["block_7", ["Compounds that contain covalent bonds exhibit different physical properties than ionic compounds. Because\nthe attraction between molecules, which are electrically neutral, is weaker than that between electrically\ncharged ions, covalent compounds generally have much lower melting and boiling points than ionic\ncompounds. In fact, many covalent compounds are liquids or gases at room temperature, and, in their solid\nstates, they are typically much softer than ionic solids. Furthermore, whereas ionic compounds are good\nconductors of electricity when dissolved in water, most covalent compounds are insoluble in water; since they\nare electrically neutral, they are poor conductors of electricity in any state.\n"]], ["block_8", [" Formation of Covalent Bonds \n"]], ["block_9", ["Nonmetal atoms frequently form covalent bonds with other nonmetal atoms. For example, the hydrogen\nmolecule, H2, contains a covalent bond between its two hydrogen atoms. Figure 7.4 illustrates why this bond is\nformed. Starting on the far right, we have two separate hydrogen atoms with a particular potential energy,\nindicated by the red line. Along the x-axis is the distance between the two atoms. As the two atoms approach\neach other (moving left along the x-axis), their valence orbitals (1s) begin to overlap. The single electrons on\neach hydrogen atom then interact with both atomic nuclei, occupying the space around both atoms. The strong\nattraction of each shared electron to both nuclei stabilizes the system, and the potential energy decreases as\nthe bond distance decreases. If the atoms continue to approach each other, the positive charges in the two\nnuclei begin to repel each other, and the potential energy increases. The bond length is determined by the\ndistance at which the lowest potential energy is achieved.\n"]], ["block_10", ["\u2022\nDescribe the formation of covalent bonds\n"]], ["block_11", ["\u2022\nDefine electronegativity and assess the polarity of covalent bonds\n"]], ["block_12", [" 7.2 \u2022 Covalent Bonding \n 317 \n"]]], "page_331": [["block_0", [" 318 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", [{"image_0": "331_0.png", "coords": [72, 57, 540, 516]}]], ["block_2", [" FIGURE 7.4 \nThe potential energy of two separate hydrogen atoms (right) decreases as they approach each other,\n"]], ["block_3", ["and the single electrons on each atom are shared to form a covalent bond. The bond length is the internuclear\ndistance at which the lowest potential energy is achieved.\n"]], ["block_4", ["It is essential to remember that energy must be added to break chemical bonds (an endothermic process),\nwhereas forming chemical bonds releases energy (an exothermic process). In the case of H2, the covalent bond\nis very strong; a large amount of energy, 436 kJ, must be added to break the bonds in one mole of hydrogen\nmolecules and cause the atoms to separate:\n"]], ["block_5", ["Conversely, the same amount of energy is released when one mole of H2 molecules forms from two moles of H\natoms:\n"]], ["block_6", [" Pure vs. Polar Covalent Bonds \n"]], ["block_7", ["If the atoms that form a covalent bond are identical, as in H2, Cl2, and other diatomic molecules, then the\nelectrons in the bond must be shared equally. We refer to this as a pure covalent bond . Electrons shared in\n"]], ["block_8", [" Access for free at openstax.org \n"]]], "page_332": [["block_0", ["pure covalent bonds have an equal probability of being near each nucleus.\n"]], ["block_1", ["In the case of Cl2, each atom starts off with seven valence electrons, and each Cl shares one electron with the\nother, forming one covalent bond:\n"]], ["block_2", ["The total number of electrons around each individual atom consists of six nonbonding electrons and two\nshared (i.e., bonding) electrons for eight total electrons, matching the number of valence electrons in the noble\ngas argon. Since the bonding atoms are identical, Cl2 also features a pure covalent bond.\n"]], ["block_3", ["When the atoms linked by a covalent bond are different, the bonding electrons are shared, but no longer\nequally. Instead, the bonding electrons are more attracted to one atom than the other, giving rise to a shift of\nelectron density toward that atom. This unequal distribution of electrons is known as a polar covalent bond ,\ncharacterized by a partial positive charge on one atom and a partial negative charge on the other. The atom\nthat attracts the electrons more strongly acquires the partial negative charge and vice versa. For example, the\nelectrons in the H\u2013Cl bond of a hydrogen chloride molecule spend more time near the chlorine atom than near\nthe hydrogen atom. Thus, in an HCl molecule, the chlorine atom carries a partial negative charge and the\nhydrogen atom has a partial positive charge. Figure 7.5 shows the distribution of electrons in the H\u2013Cl bond.\nNote that the shaded area around Cl is much larger than it is around H. Compare this to Figure 7.4, which\nshows the even distribution of electrons in the H2 nonpolar bond.\n"]], ["block_4", ["We sometimes designate the positive and negative atoms in a polar covalent bond using a lowercase Greek\nletter \u201cdelta,\u201d \u03b4, with a plus sign or minus sign to indicate whether the atom has a partial positive charge (\u03b4+) or\na partial negative charge (\u03b4\u2013). This symbolism is shown for the H\u2013Cl molecule in Figure 7.5.\n"]], ["block_5", [" FIGURE 7.5 \n(a) The distribution of electron density in the HCl molecule is uneven. The electron density is greater\n"]], ["block_6", ["around the chlorine nucleus. The small, black dots indicate the location of the hydrogen and chlorine nuclei in the\nmolecule. (b) Symbols \u03b4+ and \u03b4\u2013 indicate the polarity of the H\u2013Cl bond.\n"]], ["block_7", [" Electronegativity \n"]], ["block_8", ["Whether a bond is nonpolar or polar covalent is determined by a property of the bonding atoms called\n electronegativity . Electronegativity is a measure of the tendency of an atom to attract electrons (or electron\ndensity) towards itself. It determines how the shared electrons are distributed between the two atoms in a\nbond. The more strongly an atom attracts the electrons in its bonds, the larger its electronegativity. Electrons\nin a polar covalent bond are shifted toward the more electronegative atom; thus, the more electronegative\natom is the one with the partial negative charge. The greater the difference in electronegativity, the more\npolarized the electron distribution and the larger the partial charges of the atoms.\n"]], ["block_9", ["Figure 7.6 shows the electronegativity values of the elements as proposed by one of the most famous chemists\nof the twentieth century: Linus Pauling (Figure 7.7). In general, electronegativity increases from left to right\nacross a period in the periodic table and decreases down a group. Thus, the nonmetals, which lie in the upper\nright, tend to have the highest electronegativities, with fluorine the most electronegative element of all (EN =\n4.0). Metals tend to be less electronegative elements, and the group 1 metals have the lowest\nelectronegativities. Note that noble gases are excluded from this figure because these atoms usually do not\nshare electrons with others atoms since they have a full valence shell. (While noble gas compounds such as\nXeO2 do exist, they can only be formed under extreme conditions, and thus they do not fit neatly into the\ngeneral model of electronegativity.)\n"]], ["block_10", [{"image_0": "332_0.png", "coords": [246, 345, 365, 426]}]], ["block_11", [" 7.2 \u2022 Covalent Bonding \n 319 \n"]]], "page_333": [["block_0", [" 320 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", [{"image_0": "333_0.png", "coords": [72, 57, 540, 258]}]], ["block_2", [" FIGURE 7.6 \nThe electronegativity values derived by Pauling follow predictable periodic trends, with the higher\n"]], ["block_3", ["electronegativities toward the upper right of the periodic table.\n"]], ["block_4", [" Electronegativity versus Electron Affinity \nWe must be careful not to confuse electronegativity and electron affinity. The electron affinity of an element is\na measurable physical quantity, namely, the energy released or absorbed when an isolated gas-phase atom\nacquires an electron, measured in kJ/mol. Electronegativity, on the other hand, describes how tightly an atom\nattracts electrons in a bond. It is a dimensionless quantity that is calculated, not measured. Pauling derived the\nfirst electronegativity values by comparing the amounts of energy required to break different types of bonds.\nHe chose an arbitrary relative scale ranging from 0 to 4.\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", ["Portrait of a Chemist\n"]], ["block_7", [" Linus Pauling \n Linus Pauling , shown in Figure 7.7, is the only person to have received two unshared (individual) Nobel\nPrizes: one for chemistry in 1954 for his work on the nature of chemical bonds and one for peace in 1962\nfor his opposition to weapons of mass destruction. He developed many of the theories and concepts that\nare foundational to our current understanding of chemistry, including electronegativity and resonance\nstructures.\n"]], ["block_8", [" FIGURE 7.7 \nLinus Pauling (1901\u20131994) made many important contributions to the field of chemistry. He was\n"]], ["block_9", ["also a prominent activist, publicizing issues related to health and nuclear weapons.\n"]], ["block_10", ["Pauling also contributed to many other fields besides chemistry. His research on sickle cell anemia\nrevealed the cause of the disease\u2014the presence of a genetically inherited abnormal protein in the\nblood\u2014and paved the way for the field of molecular genetics. His work was also pivotal in curbing the\n"]], ["block_11", [{"image_1": "333_1.png", "coords": [247, 498, 364, 640]}]]], "page_334": [["block_0", [" Electronegativity and Bond Type \nThe absolute value of the difference in electronegativity (\u0394EN) of two bonded atoms provides a rough measure\nof the polarity to be expected in the bond and, thus, the bond type. When the difference is very small or zero,\nthe bond is covalent and nonpolar. When it is large, the bond is polar covalent or ionic. The absolute values of\nthe electronegativity differences between the atoms in the bonds H\u2013H, H\u2013Cl, and Na\u2013Cl are 0 (nonpolar), 0.9\n(polar covalent), and 2.1 (ionic), respectively. The degree to which electrons are shared between atoms varies\nfrom completely equal (pure covalent bonding) to not at all (ionic bonding). Figure 7.8 shows the relationship\nbetween electronegativity difference and bond type.\n"]], ["block_1", [{"image_0": "334_0.png", "coords": [72, 217, 540, 386]}]], ["block_2", ["A rough approximation of the electronegativity differences associated with covalent, polar covalent, and ionic\nbonds is shown in Figure 7.8. This table is just a general guide, however, with many exceptions. For example,\nthe H and F atoms in HF have an electronegativity difference of 1.9, and the N and H atoms in NH3 a difference\nof 0.9, yet both of these compounds form bonds that are considered polar covalent. Likewise, the Na and Cl\natoms in NaCl have an electronegativity difference of 2.1, and the Mn and I atoms in MnI2 have a difference of\n1.0, yet both of these substances form ionic compounds.\n"]], ["block_3", ["The best guide to the covalent or ionic character of a bond is to consider the types of atoms involved and their\nrelative positions in the periodic table. Bonds between two nonmetals are generally covalent; bonding between\na metal and a nonmetal is often ionic.\n"]], ["block_4", ["Some compounds contain both covalent and ionic bonds. The atoms in polyatomic ions, such as OH,\nand\nare held together by polar covalent bonds. However, these polyatomic ions form ionic compounds\n"]], ["block_5", ["by combining with ions of opposite charge. For example, potassium nitrate, KNO3, contains the Kcation and\nthe polyatomic\nanion. Thus, bonding in potassium nitrate is ionic, resulting from the electrostatic\n"]], ["block_6", ["attraction between the ions Kand\nas well as covalent between the nitrogen and oxygen atoms in\n"]], ["block_7", [" Electronegativity and Bond Polarity \n"]], ["block_8", ["Bond polarities play an important role in determining the structure of proteins. Using the electronegativity\nvalues in Figure 7.6, arrange the following covalent bonds\u2014all commonly found in amino acids\u2014in order of\nincreasing polarity. Then designate the positive and negative atoms using the symbols \u03b4+ and \u03b4\u2013:\n"]], ["block_9", ["C\u2013H, C\u2013N, C\u2013O, N\u2013H, O\u2013H, S\u2013H\n"]], ["block_10", ["testing of nuclear weapons; he proved that radioactive fallout from nuclear testing posed a public health\nrisk.\n"]], ["block_11", [" FIGURE 7.8 \nAs the electronegativity difference increases between two atoms, the bond becomes more ionic.\n"]], ["block_12", ["EXAMPLE 7.3\n"]], ["block_13", [" 7.2 \u2022 Covalent Bonding \n 321 \n"]]], "page_335": [["block_0", [" 322 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", [" Solution \n"]], ["block_2", ["The polarity of these bonds increases as the absolute value of the electronegativity difference increases. The\natom with the \u03b4\u2013 designation is the more electronegative of the two. Table 7.1 shows these bonds in order of\nincreasing polarity.\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["Silicones are polymeric compounds containing, among others, the following types of covalent bonds: Si\u2013O,\nSi\u2013C, C\u2013H, and C\u2013C. Using the electronegativity values in Figure 7.6, arrange the bonds in order of increasing\npolarity and designate the positive and negative atoms using the symbols \u03b4+ and \u03b4\u2013.\n"]], ["block_5", [" Answer: \n"]], ["block_6", [" 7.3 Lewis Symbols and Structures \n"]], ["block_7", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["\u2022\nWrite Lewis symbols for neutral atoms and ions\n"]], ["block_10", ["\u2022\nDraw Lewis structures depicting the bonding in simple molecules\n"]], ["block_11", [" TABLE 7.1 \n"]], ["block_12", [" Bond \n Electronegativity Difference \n Polarity \n"]], ["block_13", ["C\u2013C\n0.0\nnonpolar\n"]], ["block_14", ["C\u2013H\n0.4\n"]], ["block_15", ["Si\u2013C\n0.7\n"]], ["block_16", ["Si\u2013O\n1.7\n"]], ["block_17", ["Bond Polarity and Electronegativity Difference\n"]], ["block_18", [" Bond \n \u0394EN \n Polarity \n"]], ["block_19", ["C\u2013H\n0.4\n"]], ["block_20", ["S\u2013H\n0.4\n"]], ["block_21", ["C\u2013N\n0.5\n"]], ["block_22", ["N\u2013H\n0.9\n"]], ["block_23", ["C\u2013O\n1.0\n"]], ["block_24", ["O\u2013H\n1.4\n"]]], "page_336": [["block_0", ["Thus far in this chapter, we have discussed the various types of bonds that form between atoms and/or ions. In\nall cases, these bonds involve the sharing or transfer of valence shell electrons between atoms. In this section,\nwe will explore the typical method for depicting valence shell electrons and chemical bonds, namely Lewis\nsymbols and Lewis structures.\n"]], ["block_1", [" Lewis Symbols \n"]], ["block_2", ["We use Lewis symbols to describe valence electron configurations of atoms and monatomic ions. A Lewis \n symbol consists of an elemental symbol surrounded by one dot for each of its valence electrons:\n"]], ["block_3", [{"image_0": "336_0.png", "coords": [72, 165, 189, 177]}]], ["block_4", ["Figure 7.9 shows the Lewis symbols for the elements of the third period of the periodic table.\n"]], ["block_5", [{"image_1": "336_1.png", "coords": [72, 199, 540, 420]}]], ["block_6", [" FIGURE 7.9 \nLewis symbols illustrating the number of valence electrons for each element in the third period of the\n"]], ["block_7", ["periodic table.\n"]], ["block_8", ["Lewis symbols can also be used to illustrate the formation of cations from atoms, as shown here for sodium\nand calcium:\n"]], ["block_9", [{"image_2": "336_2.png", "coords": [72, 486, 540, 529]}]], ["block_10", ["Likewise, they can be used to show the formation of anions from atoms, as shown here for chlorine and sulfur:\n"]], ["block_11", [{"image_3": "336_3.png", "coords": [72, 551, 540, 598]}]], ["block_12", ["Figure 7.10 demonstrates the use of Lewis symbols to show the transfer of electrons during the formation of\nionic compounds.\n"]], ["block_13", [" 7.3 \u2022 Lewis Symbols and Structures \n 323 \n"]]], "page_337": [["block_0", [" 324 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", [{"image_0": "337_0.png", "coords": [72, 57, 540, 299]}]], ["block_2", [" FIGURE 7.10 \nCations are formed when atoms lose electrons, represented by fewer Lewis dots, whereas anions are\n"]], ["block_3", ["formed by atoms gaining electrons. The total number of electrons does not change.\n"]], ["block_4", [" Lewis Structures \n"]], ["block_5", ["We also use Lewis symbols to indicate the formation of covalent bonds, which are shown in Lewis structures ,\ndrawings that describe the bonding in molecules and polyatomic ions. For example, when two chlorine atoms\nform a chlorine molecule, they share one pair of electrons:\n"]], ["block_6", [{"image_1": "337_1.png", "coords": [72, 397, 210, 442]}]], ["block_7", ["The Lewis structure indicates that each Cl atom has three pairs of electrons that are not used in bonding\n(called lone pairs ) and one shared pair of electrons (written between the atoms). A dash (or line) is sometimes\nused to indicate a shared pair of electrons:\n"]], ["block_8", [{"image_2": "337_2.png", "coords": [72, 489, 167, 512]}]], ["block_9", ["A single shared pair of electrons is called a single bond . Each Cl atom interacts with eight valence electrons:\nthe six in the lone pairs and the two in the single bond.\n"]], ["block_10", [" The Octet Rule \nThe other halogen molecules (F2, Br2, I2, and At2) form bonds like those in the chlorine molecule: one single\nbond between atoms and three lone pairs of electrons per atom. This allows each halogen atom to have a noble\ngas electron configuration. The tendency of main group atoms to form enough bonds to obtain eight valence\nelectrons is known as the octet rule .\n"]], ["block_11", ["The number of bonds that an atom can form can often be predicted from the number of electrons needed to\nreach an octet (eight valence electrons); this is especially true of the nonmetals of the second period of the\nperiodic table (C, N, O, and F). For example, each atom of a group 14 element has four electrons in its\noutermost shell and therefore requires four more electrons to reach an octet. These four electrons can be\ngained by forming four covalent bonds, as illustrated here for carbon in CCl4 (carbon tetrachloride) and silicon\nin SiH4 (silane). Because hydrogen only needs two electrons to fill its valence shell, it is an exception to the\noctet rule. The transition elements and inner transition elements also do not follow the octet rule:\n"]], ["block_12", [" Access for free at openstax.org \n"]]], "page_338": [["block_0", [{"image_0": "338_0.png", "coords": [72, 57, 333, 135]}]], ["block_1", ["Group 15 elements such as nitrogen have five valence electrons in the atomic Lewis symbol: one lone pair and\nthree unpaired electrons. To obtain an octet, these atoms form three covalent bonds, as in NH3 (ammonia).\nOxygen and other atoms in group 16 obtain an octet by forming two covalent bonds:\n"]], ["block_2", [{"image_1": "338_1.png", "coords": [72, 182, 257, 246]}]], ["block_3", [" Double and Triple Bonds \nAs previously mentioned, when a pair of atoms shares one pair of electrons, we call this a single bond.\nHowever, a pair of atoms may need to share more than one pair of electrons in order to achieve the requisite\noctet. A double bond forms when two pairs of electrons are shared between a pair of atoms, as between the\ncarbon and oxygen atoms in CH2O (formaldehyde) and between the two carbon atoms in C2H4 (ethylene):\n"]], ["block_4", [{"image_2": "338_2.png", "coords": [72, 325, 356, 391]}]], ["block_5", ["A triple bond forms when three electron pairs are shared by a pair of atoms, as in carbon monoxide (CO) and\nthe cyanide ion (CN):\n"]], ["block_6", [{"image_3": "338_3.png", "coords": [72, 425, 334, 460]}]], ["block_7", [" Writing Lewis Structures with the Octet Rule \n"]], ["block_8", ["For very simple molecules and molecular ions, we can write the Lewis structures by merely pairing up the\nunpaired electrons on the constituent atoms. See these examples:\n"]], ["block_9", [{"image_4": "338_4.png", "coords": [72, 521, 306, 619]}]], ["block_10", ["For more complicated molecules and molecular ions, it is helpful to follow the step-by-step procedure outlined\nhere:\n"]], ["block_11", ["1.\nDetermine the total number of valence (outer shell) electrons. For cations, subtract one electron for each\npositive charge. For anions, add one electron for each negative charge.\n"]], ["block_12", ["2.\nDraw a skeleton structure of the molecule or ion, arranging the atoms around a central atom. (Generally,\nthe least electronegative element should be placed in the center.) Connect each atom to the central atom\nwith a single bond (one electron pair).\n"]], ["block_13", ["3.\nDistribute the remaining electrons as lone pairs on the terminal atoms (except hydrogen), completing an\n"]], ["block_14", [" 7.3 \u2022 Lewis Symbols and Structures \n 325 \n"]]], "page_339": [["block_0", [" 326 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", ["Let us determine the Lewis structures of SiH4,\nNO, and OF2 as examples in following this procedure:\n"]], ["block_2", [" Access for free at openstax.org \n"]], ["block_3", ["4.\nPlace all remaining electrons on the central atom.\n"]], ["block_4", ["5.\nRearrange the electrons of the outer atoms to make multiple bonds with the central atom in order to obtain\noctets wherever possible.\n"]], ["block_5", ["1.\nDetermine the total number of valence (outer shell) electrons in the molecule or ion.\n"]], ["block_6", ["2.\nDraw a skeleton structure of the molecule or ion, arranging the atoms around a central atom and\nconnecting each atom to the central atom with a single (one electron pair) bond. (Note that we denote ions\nwith brackets around the structure, indicating the charge outside the brackets:)\n"]], ["block_7", ["\u25e6\nFor a molecule, we add the number of valence electrons on each atom in the molecule:\n"]], ["block_8", ["\u25e6\nFor a negative ion, such as\nwe add the number of valence electrons on the atoms to the number of\n"]], ["block_9", ["\u25e6\nFor a positive ion, such as NO, we add the number of valence electrons on the atoms in the ion and then\nsubtract the number of positive charges on the ion (one electron is lost for each single positive charge)\nfrom the total number of valence electrons:\n"]], ["block_10", ["\u25e6\nSince OF2 is a neutral molecule, we simply add the number of valence electrons:\n"]], ["block_11", ["octet around each atom.\n"]], ["block_12", ["negative charges on the ion (one electron is gained for each single negative charge):\n"]]], "page_340": [["block_0", [" Writing Lewis Structures \n"]], ["block_1", ["NASA\u2019s Cassini-Huygens mission detected a large cloud of toxic hydrogen cyanide (HCN) on Titan, one of\nSaturn\u2019s moons. Titan also contains ethane (H3CCH3), acetylene (HCCH), and ammonia (NH3). What are the\nLewis structures of these molecules?\n"]], ["block_2", ["3.\nDistribute the remaining electrons as lone pairs on the terminal atoms (except hydrogen) to complete their\nvalence shells with an octet of electrons.\n"]], ["block_3", ["4.\nPlace all remaining electrons on the central atom.\n"]], ["block_4", ["5.\nRearrange the electrons of the outer atoms to make multiple bonds with the central atom in order to obtain\noctets wherever possible.\n"]], ["block_5", ["\u25e6\nThere are no remaining electrons on SiH4, so it is unchanged:\n"]], ["block_6", ["\u25e6\nFor SiH4,\nand NO, there are no remaining electrons; we already placed all of the electrons\n"]], ["block_7", ["\u25e6\nFor OF2, we had 16 electrons remaining in Step 3, and we placed 12, leaving 4 to be placed on the central\natom:\n"]], ["block_8", ["\u25e6\nSiH4: Si already has an octet, so nothing needs to be done.\n"]], ["block_9", ["\u25e6\nWe have distributed the valence electrons as lone pairs on the oxygen atoms, but the carbon\n"]], ["block_10", ["\u25e6\nNO: For this ion, we added eight valence electrons, but neither atom has an octet. We cannot add any\nmore electrons since we have already used the total that we found in Step 1, so we must move electrons to\nform a multiple bond:\n"]], ["block_11", ["\u25e6\nIn OF2, each atom has an octet as drawn, so nothing changes.\n"]], ["block_12", [{"image_0": "340_0.png", "coords": [90, 57, 441, 113]}]], ["block_13", ["When several arrangements of atoms are possible, as for\nwe must use experimental evidence to\n"]], ["block_14", ["choose the correct one. In general, the less electronegative elements are more likely to be central atoms. In\n"]], ["block_15", ["atoms surrounding it. Other examples include P in POCl3, S in SO2, and Cl in\nAn exception is that\n"]], ["block_16", ["hydrogen is almost never a central atom. As the most electronegative element, fluorine also cannot be a\ncentral atom.\n"]], ["block_17", [{"image_1": "340_1.png", "coords": [90, 230, 441, 284]}]], ["block_18", ["determined in Step 1.\n"]], ["block_19", [{"image_2": "340_2.png", "coords": [90, 356, 150, 378]}]], ["block_20", ["atom lacks an octet:\n"]], ["block_21", [{"image_3": "340_3.png", "coords": [90, 450, 324, 500]}]], ["block_22", [{"image_4": "340_4.png", "coords": [90, 541, 324, 568]}]], ["block_23", ["This still does not produce an octet, so we must move another pair, forming a triple bond:\n"]], ["block_24", [{"image_5": "340_5.png", "coords": [90, 584, 207, 611]}]], ["block_25", ["EXAMPLE 7.4\n"]], ["block_26", ["the less electronegative carbon atom occupies the central position with the oxygen and hydrogen\n"]], ["block_27", [" 7.3 \u2022 Lewis Symbols and Structures \n 327 \n"]]], "page_341": [["block_0", [" 328 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", [" Solution \n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["Both carbon monoxide, CO, and carbon dioxide, CO2, are products of the combustion of fossil fuels. Both of\nthese gases also cause problems: CO is toxic and CO2 has been implicated in global climate change. What are\nthe Lewis structures of these two molecules?\n"]], ["block_4", [" Answer: \n"]], ["block_5", [{"image_0": "341_0.png", "coords": [72, 702, 189, 720]}]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", ["HCN: no electrons remain\nH3CCH3: no electrons remain\nHCCH: four electrons placed on carbon\nNH3: two electrons placed on nitrogen\nStep 5. Where needed, rearrange electrons to form multiple bonds in order to obtain an octet on each\natom:\nHCN: form two more C\u2013N bonds\nH3CCH3: all atoms have the correct number of electrons\nHCCH: form a triple bond between the two carbon atoms\nNH3: all atoms have the correct number of electrons\n"]], ["block_8", ["Step 1. Calculate the number of valence electrons.\nHCN: (1\n1) + (4\n1) + (5\n1) = 10\n"]], ["block_9", ["H3CCH3: (1\n3) + (2\n4) + (1\n3) = 14\n"]], ["block_10", ["HCCH: (1\n1) + (2\n4) + (1\n1) = 10\n"]], ["block_11", ["NH3: (5\n1) + (3\n1) = 8\n"]], ["block_12", ["Step 2. Draw a skeleton and connect the atoms with single bonds. Remember that H is never a central\natom:\n"]], ["block_13", [{"image_1": "341_1.png", "coords": [90, 165, 441, 222]}]], ["block_14", ["Step 3. Where needed, distribute electrons to the terminal atoms:\n"]], ["block_15", [{"image_2": "341_2.png", "coords": [90, 238, 441, 294]}]], ["block_16", ["HCN: six electrons placed on N\nH3CCH3: no electrons remain\nHCCH: no terminal atoms capable of accepting electrons\nNH3: no terminal atoms capable of accepting electrons\nStep 4. Where needed, place remaining electrons on the central atom:\n"]], ["block_17", [{"image_3": "341_3.png", "coords": [90, 360, 441, 417]}]], ["block_18", [{"image_4": "341_4.png", "coords": [90, 546, 441, 618]}]]], "page_342": [["block_0", [" Fullerene Chemistry \nCarbon, in various forms and compounds, has been known since prehistoric times, . Soot has been used as a\npigment (often called carbon black) for thousands of years. Charcoal, high in carbon content, has likewise been\ncritical to human development. Carbon is the key additive to iron in the steelmaking process, and diamonds\nhave a unique place in both culture and industry. With all this usage came significant study, particularly with\nthe emergence of organic chemistry. And even with all the known forms and functions of the element,\nscientists began to uncover the potential for even more varied and extensive carbon structures.\n"]], ["block_1", ["As early as the 1960s, chemists began to observe complex carbon structures, but they had little evidence to\nsupport their concepts, or their work did not make it into the mainstream. Eiji Osawa predicted a spherical\nform based on observations of a similar structure, but his work was not widely known outside Japan. In a\nsimilar manner, the most comprehensive advance was likely computational chemist Elena Galpern's, who in\n1973 predicted a highly stable, 60-carbon molecule; her work was also isolated to her native Russia. Still later,\nHarold Kroto, working with Canadian radio astronomers, sought to uncover the nature of long carbon chains\nthat had been discovered in interstellar space.\n"]], ["block_2", ["Kroto sought to use a machine developed by Richard Smalley's team at Rice University to learn more about\nthese structures. Together with Robert Curl, who had introduced them, and three graduate students\u2014James\nHeath, Sean O\u2019Brien, and Yuan Liu\u2014they performed an intensive series of experiments that led to a major\ndiscovery.\n"]], ["block_3", ["In 1996, the Nobel Prize in Chemistry was awarded to Richard Smalley (Figure 7.11), Robert Curl, and Harold\nKroto for their work in discovering a new form of carbon, the C60 buckminsterfullerene molecule (Figure 7.1).\nAn entire class of compounds, including spheres and tubes of various shapes, were discovered based on C60.\nThis type of molecule, called a fullerene, shows promise in a variety of applications. Because of their size and\nshape, fullerenes can encapsulate other molecules, so they have shown potential in various applications from\nhydrogen storage to targeted drug delivery systems. They also possess unique electronic and optical\nproperties that have been put to good use in solar powered devices and chemical sensors.\n"]], ["block_4", [" FIGURE 7.11 \nRichard Smalley (1943\u20132005), a professor of physics, chemistry, and astronomy at Rice University,\n"]], ["block_5", ["was one of the leading advocates for fullerene chemistry. Upon his death in 2005, the US Senate honored him as the\n\u201cFather of Nanotechnology.\u201d (credit: United States Department of Energy)\n"]], ["block_6", [" Exceptions to the Octet Rule \n"]], ["block_7", ["Many covalent molecules have central atoms that do not have eight electrons in their Lewis structures. These\nmolecules fall into three categories:\n"]], ["block_8", ["HOW SCIENCES INTERCONNECT\n"]], ["block_9", [{"image_0": "342_0.png", "coords": [189, 432, 423, 610]}]], ["block_10", [" 7.3 \u2022 Lewis Symbols and Structures \n 329 \n"]]], "page_343": [["block_0", [" 330 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", [" Odd-electron Molecules \nWe call molecules that contain an odd number of electrons free radicals . Nitric oxide, NO, is an example of an\nodd-electron molecule; it is produced in internal combustion engines when oxygen and nitrogen react at high\ntemperatures.\n"]], ["block_2", ["To draw the Lewis structure for an odd-electron molecule like NO, we follow the same five steps we would for\nother molecules, but with a few minor changes:\n"]], ["block_3", [" Electron-deficient Molecules \nWe will also encounter a few molecules that contain central atoms that do not have a filled valence shell.\nGenerally, these are molecules with central atoms from groups 2 and 13, outer atoms that are hydrogen, or\nother atoms that do not form multiple bonds. For example, in the Lewis structures of beryllium dihydride,\nBeH2, and boron trifluoride, BF3, the beryllium and boron atoms each have only four and six electrons,\nrespectively. It is possible to draw a structure with a double bond between a boron atom and a fluorine atom in\nBF3, satisfying the octet rule, but experimental evidence indicates the bond lengths are closer to that expected\nfor B\u2013F single bonds. This suggests the best Lewis structure has three B\u2013F single bonds and an electron\ndeficient boron. The reactivity of the compound is also consistent with an electron deficient boron. However,\nthe B\u2013F bonds are slightly shorter than what is actually expected for B\u2013F single bonds, indicating that some\ndouble bond character is found in the actual molecule.\n"]], ["block_4", [{"image_0": "343_0.png", "coords": [72, 628, 201, 678]}]], ["block_5", ["An atom like the boron atom in BF3, which does not have eight electrons, is very reactive. It readily combines\nwith a molecule containing an atom with a lone pair of electrons. For example, NH3 reacts with BF3 because\nthe lone pair on nitrogen can be shared with the boron atom:\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", ["1.\nDetermine the total number of valence (outer shell) electrons. The sum of the valence electrons is 5 (from\nN) + 6 (from O) = 11. The odd number immediately tells us that we have a free radical, so we know that not\nevery atom can have eight electrons in its valence shell.\n"]], ["block_8", ["2.\nDraw a skeleton structure of the molecule. We can easily draw a skeleton with an N\u2013O single bond:\nN\u2013O\n"]], ["block_9", ["3.\nDistribute the remaining electrons as lone pairs on the terminal atoms. In this case, there is no central\natom, so we distribute the electrons around both atoms. We give eight electrons to the more\nelectronegative atom in these situations; thus oxygen has the filled valence shell:\n"]], ["block_10", ["4.\nPlace all remaining electrons on the central atom. Since there are no remaining electrons, this step does\nnot apply.\n"]], ["block_11", ["5.\nRearrange the electrons to make multiple bonds with the central atom in order to obtain octets wherever\npossible. We know that an odd-electron molecule cannot have an octet for every atom, but we want to get\neach atom as close to an octet as possible. In this case, nitrogen has only five electrons around it. To move\ncloser to an octet for nitrogen, we take one of the lone pairs from oxygen and use it to form a NO double\nbond. (We cannot take another lone pair of electrons on oxygen and form a triple bond because nitrogen\nwould then have nine electrons:)\n"]], ["block_12", ["\u2022\nOdd-electron molecules have an odd number of valence electrons, and therefore have an unpaired\nelectron.\n"]], ["block_13", ["\u2022\nElectron-deficient molecules have a central atom that has fewer electrons than needed for a noble gas\nconfiguration.\n"]], ["block_14", ["\u2022\nHypervalent molecules have a central atom that has more electrons than needed for a noble gas\nconfiguration.\n"]], ["block_15", [{"image_1": "343_1.png", "coords": [90, 329, 131, 351]}]], ["block_16", [{"image_2": "343_2.png", "coords": [90, 455, 131, 473]}]]], "page_344": [["block_0", [{"image_0": "344_0.png", "coords": [72, 57, 423, 118]}]], ["block_1", [" Hypervalent Molecules \nElements in the second period of the periodic table (n = 2) can accommodate only eight electrons in their\nvalence shell orbitals because they have only four valence orbitals (one 2s and three 2p orbitals). Elements in\nthe third and higher periods (n \u2265 3) have more than four valence orbitals and can share more than four pairs of\nelectrons with other atoms because they have empty d orbitals in the same shell. Molecules formed from these\nelements are sometimes called hypervalent molecules . Figure 7.12 shows the Lewis structures for two\nhypervalent molecules, PCl5 and SF6.\n"]], ["block_2", [" FIGURE 7.12 \nIn PCl5, the central atom phosphorus shares five pairs of electrons. In SF6, sulfur shares six pairs of\n"]], ["block_3", ["electrons.\n"]], ["block_4", ["In some hypervalent molecules, such as IF5 and XeF4, some of the electrons in the outer shell of the central\natom are lone pairs:\n"]], ["block_5", [{"image_1": "344_1.png", "coords": [72, 350, 306, 410]}]], ["block_6", ["When we write the Lewis structures for these molecules, we find that we have electrons left over after filling the\nvalence shells of the outer atoms with eight electrons. These additional electrons must be assigned to the\ncentral atom.\n"]], ["block_7", [" Writing Lewis Structures: Octet Rule Violations \n"]], ["block_8", ["Xenon is a noble gas, but it forms a number of stable compounds. We examined XeF4 earlier. What are the\nLewis structures of XeF2 and XeF6?\n"]], ["block_9", [" Solution \n"]], ["block_10", ["We can draw the Lewis structure of any covalent molecule by following the six steps discussed earlier. In this\ncase, we can condense the last few steps, since not all of them apply.\n"]], ["block_11", ["Step 1. Calculate the number of valence electrons:\nXeF2: 8 + (2\n7) = 22\n"]], ["block_12", ["XeF6: 8 + (6\n7) = 50\n"]], ["block_13", ["Step 2. Draw a skeleton joining the atoms by single bonds. Xenon will be the central atom because fluorine\ncannot be a central atom:\n"]], ["block_14", [{"image_2": "344_2.png", "coords": [90, 647, 210, 696]}]], ["block_15", ["Step 3. Distribute the remaining electrons.\nXeF2: We place three lone pairs of electrons around each F atom, accounting for 12 electrons and giving\n"]], ["block_16", ["EXAMPLE 7.5\n"]], ["block_17", [{"image_3": "344_3.png", "coords": [235, 222, 376, 284]}]], ["block_18", [" 7.3 \u2022 Lewis Symbols and Structures \n 331 \n"]]], "page_345": [["block_0", [" 332 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["The halogens form a class of compounds called the interhalogens, in which halogen atoms covalently bond to\neach other. Write the Lewis structures for the interhalogens BrCl3 and\n"]], ["block_3", [" Answer: \n"]], ["block_4", [{"image_0": "345_0.png", "coords": [72, 294, 306, 356]}]], ["block_5", [" 7.4 Formal Charges and Resonance \n"]], ["block_6", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_7", ["In the previous section, we discussed how to write Lewis structures for molecules and polyatomic ions. As we\nhave seen, however, in some cases, there is seemingly more than one valid structure for a molecule. We can\nuse the concept of formal charges to help us predict the most appropriate Lewis structure when more than one\nis reasonable.\n"]], ["block_8", [" Calculating Formal Charge \n"]], ["block_9", ["The formal charge of an atom in a molecule is the hypothetical charge the atom would have if we could\nredistribute the electrons in the bonds evenly between the atoms. Another way of saying this is that formal\ncharge results when we take the number of valence electrons of a neutral atom, subtract the nonbonding\nelectrons, and then subtract the number of bonds connected to that atom in the Lewis structure.\n"]], ["block_10", ["Thus, we calculate formal charge as follows:\n"]], ["block_11", ["We can double-check formal charge calculations by determining the sum of the formal charges for the whole\nstructure. The sum of the formal charges of all atoms in a molecule must be zero; the sum of the formal\ncharges in an ion should equal the charge of the ion.\n"]], ["block_12", ["We must remember that the formal charge calculated for an atom is not the actual charge of the atom in the\nmolecule. Formal charge is only a useful bookkeeping procedure; it does not indicate the presence of actual\ncharges.\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", ["\u2022\nCompute formal charges for atoms in any Lewis structure\n"]], ["block_15", ["\u2022\nUse formal charges to identify the most reasonable Lewis structure for a given molecule\n"]], ["block_16", ["\u2022\nExplain the concept of resonance and draw Lewis structures representing resonance forms for a given molecule\n"]], ["block_17", ["each F atom 8 electrons. Thus, six electrons (three lone pairs) remain. These lone pairs must be placed on\nthe Xe atom. This is acceptable because Xe atoms have empty valence shell d orbitals and can\naccommodate more than eight electrons. The Lewis structure of XeF2 shows two bonding pairs and three\nlone pairs of electrons around the Xe atom:\n"]], ["block_18", [{"image_1": "345_1.png", "coords": [90, 108, 150, 129]}]], ["block_19", ["XeF6: We place three lone pairs of electrons around each F atom, accounting for 36 electrons. Two\nelectrons remain, and this lone pair is placed on the Xe atom:\n"]], ["block_20", [{"image_2": "345_2.png", "coords": [90, 158, 207, 223]}]]], "page_346": [["block_0", [" Calculating Formal Charge from Lewis Structures \n"]], ["block_1", ["Assign formal charges to each atom in the interhalogen ion\n"]], ["block_2", [" Solution \n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["Calculate the formal charge for each atom in the carbon monoxide molecule:\n"]], ["block_5", [{"image_0": "346_0.png", "coords": [72, 338, 113, 351]}]], ["block_6", [" Answer: \nC \u22121, O +1\n"]], ["block_7", [" Calculating Formal Charge from Lewis Structures \n"]], ["block_8", ["Assign formal charges to each atom in the interhalogen molecule BrCl3.\n"]], ["block_9", [" Solution \n"]], ["block_10", [" Check Your Learning \n"]], ["block_11", ["Determine the formal charge for each atom in NCl3.\n"]], ["block_12", [" Answer: \nN: 0; all three Cl atoms: 0\n"]], ["block_13", ["Step 1. We divide the bonding electron pairs equally for all I\u2013Cl bonds:\n"]], ["block_14", [{"image_1": "346_1.png", "coords": [90, 157, 173, 219]}]], ["block_15", ["Step 2. We assign lone pairs of electrons to their atoms. Each Cl atom now has seven electrons assigned to\nit, and the I atom has eight.\nStep 3. Subtract this number from the number of valence electrons for the neutral atom:\nI: 7 \u2013 8 = \u20131\nCl: 7 \u2013 7 = 0\nThe sum of the formal charges of all the atoms equals \u20131, which is identical to the charge of the ion (\u20131).\n"]], ["block_16", ["Step 1. Assign one of the electrons in each Br\u2013Cl bond to the Br atom and one to the Cl atom in that bond:\n"]], ["block_17", [{"image_2": "346_2.png", "coords": [90, 502, 153, 544]}]], ["block_18", ["Step 2. Assign the lone pairs to their atom. Now each Cl atom has seven electrons and the Br atom has\nseven electrons.\nStep 3. Subtract this number from the number of valence electrons for the neutral atom. This gives the\nformal charge:\nBr: 7 \u2013 7 = 0\nCl: 7 \u2013 7 = 0\nAll atoms in BrCl3 have a formal charge of zero, and the sum of the formal charges totals zero, as it must in\na neutral molecule.\n"]], ["block_19", ["EXAMPLE 7.6\n"]], ["block_20", ["EXAMPLE 7.7\n"]], ["block_21", [" 7.4 \u2022 Formal Charges and Resonance \n 333 \n"]]], "page_347": [["block_0", [" 334 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", [{"image_0": "347_0.png", "coords": [72, 57, 189, 99]}]], ["block_2", [" Using Formal Charge to Predict Molecular Structure \n"]], ["block_3", ["The arrangement of atoms in a molecule or ion is called its molecular structure . In many cases, following the\nsteps for writing Lewis structures may lead to more than one possible molecular structure\u2014different multiple\nbond and lone-pair electron placements or different arrangements of atoms, for instance. A few guidelines\ninvolving formal charge can be helpful in deciding which of the possible structures is most likely for a\nparticular molecule or ion:\n"]], ["block_4", ["To see how these guidelines apply, let us consider some possible structures for carbon dioxide, CO2. We know\nfrom our previous discussion that the less electronegative atom typically occupies the central position, but\nformal charges allow us to understand why this occurs. We can draw three possibilities for the structure:\ncarbon in the center and double bonds, carbon in the center with a single and triple bond, and oxygen in the\ncenter with double bonds:\n"]], ["block_5", [{"image_1": "347_1.png", "coords": [72, 369, 351, 410]}]], ["block_6", ["Comparing the three formal charges, we can definitively identify the structure on the left as preferable because\nit has only formal charges of zero (Guideline 1).\n"]], ["block_7", ["As another example, the thiocyanate ion, an ion formed from a carbon atom, a nitrogen atom, and a sulfur\natom, could have three different molecular structures: NCS, CNS, or CSN. The formal charges present in\neach of these molecular structures can help us pick the most likely arrangement of atoms. Possible Lewis\nstructures and the formal charges for each of the three possible structures for the thiocyanate ion are shown\nhere:\n"]], ["block_8", [{"image_2": "347_2.png", "coords": [72, 513, 423, 553]}]], ["block_9", ["Note that the sum of the formal charges in each case is equal to the charge of the ion (\u20131). However, the first\narrangement of atoms is preferred because it has the lowest number of atoms with nonzero formal charges\n(Guideline 2). Also, it places the least electronegative atom in the center, and the negative charge on the more\nelectronegative element (Guideline 4).\n"]], ["block_10", [" Using Formal Charge to Determine Molecular Structure \n"]], ["block_11", ["Nitrous oxide, N2O, commonly known as laughing gas, is used as an anesthetic in minor surgeries, such as the\nroutine extraction of wisdom teeth. Which is the more likely structure for nitrous oxide?\n"]], ["block_12", [{"image_3": "347_3.png", "coords": [72, 692, 206, 715]}]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", ["1.\nA molecular structure in which all formal charges are zero is preferable to one in which some formal\ncharges are not zero.\n"]], ["block_15", ["2.\nIf the Lewis structure must have nonzero formal charges, the arrangement with the smallest nonzero\nformal charges is preferable.\n"]], ["block_16", ["3.\nLewis structures are preferable when adjacent formal charges are zero or of the opposite sign.\n"]], ["block_17", ["4.\nWhen we must choose among several Lewis structures with similar distributions of formal charges, the\nstructure with the negative formal charges on the more electronegative atoms is preferable.\n"]], ["block_18", ["EXAMPLE 7.8\n"]]], "page_348": [["block_0", [" Solution \n"]], ["block_1", ["Determining formal charge yields the following:\n"]], ["block_2", [{"image_0": "348_0.png", "coords": [72, 91, 217, 124]}]], ["block_3", ["The structure with a terminal oxygen atom best satisfies the criteria for the most stable distribution of formal\ncharge:\n"]], ["block_4", [{"image_1": "348_1.png", "coords": [72, 158, 134, 183]}]], ["block_5", ["The number of atoms with formal charges are minimized (Guideline 2), there is no formal charge with a\nmagnitude greater than one (Guideline 2), the negative formal charge is on the more electronegative element\n(Guideline 4), and the less electronegative atom is in the center position.\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["Which is the most likely molecular structure for the nitrite\nion?\n"]], ["block_8", [{"image_2": "348_2.png", "coords": [72, 266, 258, 299]}]], ["block_9", [" Answer: \nONO\n"]], ["block_10", [" Resonance \n"]], ["block_11", ["Notice that the more likely structure for the nitrite anion in Example 7.8 may actually be drawn in two different\nways, distinguished by the locations of the N-O and N=O bonds:\n"]], ["block_12", [{"image_3": "348_3.png", "coords": [72, 402, 250, 436]}]], ["block_13", ["If nitrite ions do indeed contain a single and a double bond, we would expect for the two bond lengths to be\ndifferent. A double bond between two atoms is shorter (and stronger) than a single bond between the same two\natoms. Experiments show, however, that both N\u2013O bonds in\nhave the same strength and length, and are\n"]], ["block_14", ["identical in all other properties.\n"]], ["block_15", ["It is not possible to write a single Lewis structure for\nin which nitrogen has an octet and both bonds are\n"]], ["block_16", ["equivalent. Instead, we use the concept of resonance : if two or more Lewis structures with the same\narrangement of atoms can be written for a molecule or ion, the actual distribution of electrons is an average of\nthat shown by the various Lewis structures. The actual distribution of electrons in each of the nitrogen-oxygen\nbonds in\nis the average of a double bond and a single bond. We call the individual Lewis structures\n"]], ["block_17", [" resonance forms . The actual electronic structure of the molecule (the average of the resonance forms) is\ncalled a resonance hybrid of the individual resonance forms. A double-headed arrow between Lewis\nstructures indicates that they are resonance forms.\n"]], ["block_18", [{"image_4": "348_4.png", "coords": [72, 602, 276, 634]}]], ["block_19", ["We should remember that a molecule described as a resonance hybrid never possesses an electronic structure\ndescribed by either resonance form. It does not fluctuate between resonance forms; rather, the actual\nelectronic structure is always the average of that shown by all resonance forms. George Wheland, one of the\npioneers of resonance theory, used a historical analogy to describe the relationship between resonance forms\nand resonance hybrids. A medieval traveler, having never before seen a rhinoceros, described it as a hybrid of\na dragon and a unicorn because it had many properties in common with both. Just as a rhinoceros is neither a\ndragon sometimes nor a unicorn at other times, a resonance hybrid is neither of its resonance forms at any\n"]], ["block_20", [" 7.4 \u2022 Formal Charges and Resonance \n 335 \n"]]], "page_349": [["block_0", [" 336 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", ["given time. Like a rhinoceros, it is a real entity that experimental evidence has shown to exist. It has some\ncharacteristics in common with its resonance forms, but the resonance forms themselves are convenient,\nimaginary images (like the unicorn and the dragon).\n"]], ["block_2", ["The carbonate anion,\nprovides a second example of resonance:\n"]], ["block_3", [{"image_0": "349_0.png", "coords": [72, 121, 348, 188]}]], ["block_4", ["One oxygen atom must have a double bond to carbon to complete the octet on the central atom. All oxygen\natoms, however, are equivalent, and the double bond could form from any one of the three atoms. This gives\nrise to three resonance forms of the carbonate ion. Because we can write three identical resonance structures,\nwe know that the actual arrangement of electrons in the carbonate ion is the average of the three structures.\nAgain, experiments show that all three C\u2013O bonds are exactly the same.\n"]], ["block_5", ["Use this online quiz (http://openstax.org/l/16LewisMake) to practice your skills in drawing resonance\nstructures and estimating formal charges.\n"]], ["block_6", [" 7.5 Strengths of Ionic and Covalent Bonds \n"]], ["block_7", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_8", ["A bond\u2019s strength describes how strongly each atom is joined to another atom, and therefore how much energy\nis required to break the bond between the two atoms. In this section, you will learn about the bond strength of\ncovalent bonds, and then compare that to the strength of ionic bonds, which is related to the lattice energy of a\ncompound.\n"]], ["block_9", [" Bond Strength: Covalent Bonds \n"]], ["block_10", ["Stable molecules exist because covalent bonds hold the atoms together. We measure the strength of a covalent\nbond by the energy required to break it, that is, the energy necessary to separate the bonded atoms. Separating\nany pair of bonded atoms requires energy (see Figure 7.4). The stronger a bond, the greater the energy\nrequired to break it.\n"]], ["block_11", ["The energy required to break a specific covalent bond in one mole of gaseous molecules is called the bond\nenergy or the bond dissociation energy. The bond energy for a diatomic molecule, DX\u2013Y, is defined as the\nstandard enthalpy change for the endothermic reaction:\n"]], ["block_12", ["For example, the bond energy of the pure covalent H\u2013H bond, DH\u2013H, is 436 kJ per mole of H\u2013H bonds broken:\n"]], ["block_13", ["Molecules with three or more atoms have two or more bonds. The sum of all bond energies in such a molecule\nis equal to the standard enthalpy change for the endothermic reaction that breaks all the bonds in the\nmolecule. For example, the sum of the four C\u2013H bond energies in CH4, 1660 kJ, is equal to the standard\nenthalpy change of the reaction:\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["\u2022\nDescribe the energetics of covalent and ionic bond formation and breakage\n"]], ["block_16", ["\u2022\nUse the Born-Haber cycle to compute lattice energies for ionic compounds\n"]], ["block_17", ["\u2022\nUse average covalent bond energies to estimate enthalpies of reaction\n"]], ["block_18", ["LINK TO LEARNING\n"]]], "page_350": [["block_0", [{"image_0": "350_0.png", "coords": [72, 57, 423, 109]}]], ["block_1", ["The average C\u2013H bond energy, DC\u2013H, is 1660/4 = 415 kJ/mol because there are four moles of C\u2013H bonds broken\nper mole of the reaction. Although the four C\u2013H bonds are equivalent in the original molecule, they do not each\nrequire the same energy to break; once the first bond is broken (which requires 439 kJ/mol), the remaining\nbonds are easier to break. The 415 kJ/mol value is the average, not the exact value required to break any one\nbond.\n"]], ["block_2", ["The strength of a bond between two atoms increases as the number of electron pairs in the bond increases.\nGenerally, as the bond strength increases, the bond length decreases. Thus, we find that triple bonds are\nstronger and shorter than double bonds between the same two atoms; likewise, double bonds are stronger and\nshorter than single bonds between the same two atoms. Average bond energies for some common bonds\nappear in Table 7.2, and a comparison of bond lengths and bond strengths for some common bonds appears in\nTable 7.3. When one atom bonds to various atoms in a group, the bond strength typically decreases as we move\ndown the group. For example, C\u2013F is 439 kJ/mol, C\u2013Cl is 330 kJ/mol, and C\u2013Br is 275 kJ/mol.\n"]], ["block_3", [" Bond \n Bond Energy\n Bond \n Bond Energy\n Bond \n Bond Energy\n"]], ["block_4", ["H\u2013H\n436\nC\u2013S\n260\nF\u2013Cl\n255\n"]], ["block_5", ["H\u2013C\n415\nC\u2013Cl\n330\nF\u2013Br\n235\n"]], ["block_6", ["H\u2013N\n390\nC\u2013Br\n275\nSi\u2013Si\n230\n"]], ["block_7", ["H\u2013O\n464\nC\u2013I\n240\nSi\u2013P\n215\n"]], ["block_8", ["H\u2013F\n569\nN\u2013N\n160\nSi\u2013S\n225\n"]], ["block_9", ["H\u2013Si\n395\n418\nSi\u2013Cl\n359\n"]], ["block_10", ["H\u2013P\n320\n946\nSi\u2013Br\n290\n"]], ["block_11", ["H\u2013S\n340\nN\u2013O\n200\nSi\u2013I\n215\n"]], ["block_12", ["H\u2013Cl\n432\nN\u2013F\n270\nP\u2013P\n215\n"]], ["block_13", ["H\u2013Br\n370\nN\u2013P\n210\nP\u2013S\n230\n"]], ["block_14", ["H\u2013I\n295\nN\u2013Cl\n200\nP\u2013Cl\n330\n"]], ["block_15", ["C\u2013C\n345\nN\u2013Br\n245\nP\u2013Br\n270\n"]], ["block_16", ["C\u2013N\n290\nO\u2013F\n160\nS\u2013Cl\n250\n"]], ["block_17", ["611\nO\u2013O\n140\nP\u2013I\n215\n"]], ["block_18", ["837\n498\nS\u2013S\n215\n"]], ["block_19", [" Bond Energies (kJ/mol) \n"]], ["block_20", [" 7.5 \u2022 Strengths of Ionic and Covalent Bonds \n 337 \n"]]], "page_351": [["block_0", [" 338 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", ["We can use bond energies to calculate approximate enthalpy changes for reactions where enthalpies of\nformation are not available. Calculations of this type will also tell us whether a reaction is exothermic or\nendothermic. An exothermic reaction (\u0394H negative, heat produced) results when the bonds in the products are\nstronger than the bonds in the reactants. An endothermic reaction (\u0394H positive, heat absorbed) results when\nthe bonds in the products are weaker than those in the reactants.\n"]], ["block_2", [" Access for free at openstax.org \n"]], ["block_3", [" TABLE 7.2 \n"]], ["block_4", [" Bond \n Bond Energy\n Bond \n Bond Energy\n Bond \n Bond Energy\n"]], ["block_5", ["C\u2013O\n350\nO\u2013Cl\n205\nCl\u2013Br\n220\n"]], ["block_6", ["C\u2013F\n439\nF\u2013Si\n540\nBr\u2013I\n180\n"]], ["block_7", ["C\u2013Si\n360\nF\u2013P\n489\nI\u2013I\n150\n"]], ["block_8", ["C\u2013P\n265\nF\u2013S\n285\n"]], ["block_9", [" TABLE 7.3 \n"]], ["block_10", ["Average Bond Lengths and Bond Energies for Some Common Bonds\n"]], ["block_11", [" Bond \n Bond Length (\u00c5)\n Bond Energy (kJ/mol)\n"]], ["block_12", ["C\u2013C\n1.54\n345\n"]], ["block_13", ["C\u2013N\n1.43\n290\n"]], ["block_14", ["C\u2013O\n1.43\n350\n"]], ["block_15", ["615\nO\u2013Si\n370\nS\u2013Br\n215\n"]], ["block_16", ["891\nO\u2013P\n350\nCl\u2013Cl\n243\n"]], ["block_17", ["741\nO\u2013I\n200\nCl\u2013I\n210\n"]], ["block_18", ["1080\nF\u2013F\n160\nBr\u2013Br\n190\n"]], ["block_19", ["1.34\n611\n"]], ["block_20", ["1.20\n837\n"]], ["block_21", ["1.38\n615\n"]], ["block_22", ["1.16\n891\n"]], ["block_23", ["1.23\n741\n"]], ["block_24", ["1.13\n1080\n"]], ["block_25", [" Bond Energies (kJ/mol) \n"]]], "page_352": [["block_0", ["The enthalpy change, \u0394H, for a chemical reaction is approximately equal to the sum of the energy required to\nbreak all bonds in the reactants (energy \u201cin\u201d, positive sign) plus the energy released when all bonds are formed\nin the products (energy \u201cout,\u201d negative sign). This can be expressed mathematically in the following way:\n"]], ["block_1", ["In this expression, the symbol \u01a9 means \u201cthe sum of\u201d and D represents the bond energy in kilojoules per mole,\nwhich is always a positive number. The bond energy is obtained from a table (like Table 7.3) and will depend on\nwhether the particular bond is a single, double, or triple bond. Thus, in calculating enthalpies in this manner, it\nis important that we consider the bonding in all reactants and products. Because D values are typically\naverages for one type of bond in many different molecules, this calculation provides a rough estimate, not an\nexact value, for the enthalpy of reaction.\n"]], ["block_2", ["Consider the following reaction:\n"]], ["block_3", ["or\n"]], ["block_4", ["To form two moles of HCl, one mole of H\u2013H bonds and one mole of Cl\u2013Cl bonds must be broken. The energy\nrequired to break these bonds is the sum of the bond energy of the H\u2013H bond (436 kJ/mol) and the Cl\u2013Cl bond\n(243 kJ/mol). During the reaction, two moles of H\u2013Cl bonds are formed (bond energy = 432 kJ/mol), releasing 2\n"]], ["block_5", ["releases more energy than it consumes:\n"]], ["block_6", ["This excess energy is released as heat, so the reaction is exothermic. Appendix G gives a value for the standard\nmolar enthalpy of formation of HCl(g),\nof \u201392.307 kJ/mol. Twice that value is \u2013184.6 kJ, which agrees\n"]], ["block_7", ["well with the answer obtained earlier for the formation of two moles of HCl.\n"]], ["block_8", [" Using Bond Energies to Calculate Approximate Enthalpy Changes \n"]], ["block_9", ["Methanol, CH3OH, may be an excellent alternative fuel. The high-temperature reaction of steam and carbon\nproduces a mixture of the gases carbon monoxide, CO, and hydrogen, H2, from which methanol can be\nproduced. Using the bond energies in Table 7.3, calculate the approximate enthalpy change, \u0394H, for the\nreaction here:\n"]], ["block_10", [" Solution \n"]], ["block_11", ["First, we need to write the Lewis structures of the reactants and the products:\n"]], ["block_12", [{"image_0": "352_0.png", "coords": [72, 608, 423, 659]}]], ["block_13", ["From this, we see that \u0394H for this reaction involves the energy required to break a C\u2013O triple bond and two\nH\u2013H single bonds, as well as the energy produced by the formation of three C\u2013H single bonds, a C\u2013O single\nbond, and an O\u2013H single bond. We can express this as follows:\n"]], ["block_14", ["432 kJ; or 864 kJ. Because the bonds in the products are stronger than those in the reactants, the reaction\n"]], ["block_15", ["EXAMPLE 7.9\n"]], ["block_16", ["\u01a9\n\u01a9\n"]], ["block_17", ["\u01a9\n\u01a9\n"]], ["block_18", [" 7.5 \u2022 Strengths of Ionic and Covalent Bonds \n 339 \n"]]], "page_353": [["block_0", [" 340 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", ["Using the bond energy values in Table 7.3, we obtain:\n"]], ["block_2", ["We can compare this value to the value calculated based on\ndata from Appendix G:\n"]], ["block_3", ["Note that there is a fairly significant gap between the values calculated using the two different methods. This\noccurs because D values are the average of different bond strengths; therefore, they often give only rough\nagreement with other data.\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["Ethyl alcohol, CH3CH2OH, was one of the first organic chemicals deliberately synthesized by humans. It has\nmany uses in industry, and it is the alcohol contained in alcoholic beverages. It can be obtained by the\nfermentation of sugar or synthesized by the hydration of ethylene in the following reaction:\n"]], ["block_6", [{"image_0": "353_0.png", "coords": [72, 326, 423, 377]}]], ["block_7", ["Using the bond energies in Table 7.3, calculate an approximate enthalpy change, \u0394H, for this reaction.\n"]], ["block_8", [" Answer: \n\u201335 kJ\n"]], ["block_9", [" Ionic Bond Strength and Lattice Energy \n"]], ["block_10", ["An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The\nlattice energy of a compound is a measure of the strength of this attraction. The lattice energy ( \u0394 H lattice ) of an\nionic compound is defined as the energy required to separate one mole of the solid into its component gaseous\nions. For the ionic solid MX, the lattice energy is the enthalpy change of the process:\n"]], ["block_11", ["Note that we are using the convention where the ionic solid is separated into ions, so our lattice energies will\nbe endothermic (positive values). Some texts use the equivalent but opposite convention, defining lattice\nenergy as the energy released when separate ions combine to form a lattice and giving negative (exothermic)\nvalues. Thus, if you are looking up lattice energies in another reference, be certain to check which definition is\nbeing used. In both cases, a larger magnitude for lattice energy indicates a more stable ionic compound. For\nsodium chloride, \u0394Hlattice = 769 kJ. Thus, it requires 769 kJ to separate one mole of solid NaCl into gaseous Na\n"]], ["block_12", ["and Clions. When one mole each of gaseous Naand Clions form solid NaCl, 769 kJ of heat is released.\n"]], ["block_13", ["The lattice energy \u0394Hlattice of an ionic crystal can be expressed by the following equation (derived from\nCoulomb\u2019s law, governing the forces between electric charges):\n"]], ["block_14", ["in which C is a constant that depends on the type of crystal structure; Zand Zare the charges on the ions;\nand Ro is the interionic distance (the sum of the radii of the positive and negative ions). Thus, the lattice energy\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["\u01a9\n\u01a9\n"]]], "page_354": [["block_0", ["of an ionic crystal increases rapidly as the charges of the ions increase and the sizes of the ions decrease.\nWhen all other parameters are kept constant, doubling the charge of both the cation and anion quadruples the\nlattice energy. For example, the lattice energy of LiF (Zand Z= 1) is 1023 kJ/mol, whereas that of MgO (Zand\nZ= 2) is 3900 kJ/mol (Ro is nearly the same\u2014about 200 pm for both compounds).\n"]], ["block_1", ["Different interatomic distances produce different lattice energies. For example, we can compare the lattice\nenergy of MgF2 (2957 kJ/mol) to that of MgI2 (2327 kJ/mol) to observe the effect on lattice energy of the smaller\nionic size of Fas compared to I.\n"]], ["block_2", [" Lattice Energy Comparisons \n"]], ["block_3", ["The precious gem ruby is aluminum oxide, Al2O3, containing traces of Cr. The compound Al2Se3 is used in\nthe fabrication of some semiconductor devices. Which has the larger lattice energy, Al2O3 or Al2Se3?\n"]], ["block_4", [" Solution \n"]], ["block_5", ["In these two ionic compounds, the charges Zand Zare the same, so the difference in lattice energy will\ndepend upon Ro. The Oion is smaller than the Seion. Thus, Al2O3 would have a shorter interionic distance\nthan Al2Se3, and Al2O3 would have the larger lattice energy.\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["Zinc oxide, ZnO, is a very effective sunscreen. How would the lattice energy of ZnO compare to that of NaCl?\n"]], ["block_8", [" Answer: \nZnO would have the larger lattice energy because the Z values of both the cation and the anion in ZnO are\ngreater, and the interionic distance of ZnO is smaller than that of NaCl.\n"]], ["block_9", [" The Born-Haber Cycle \n"]], ["block_10", ["It is not possible to measure lattice energies directly. However, the lattice energy can be calculated using the\nequation given in the previous section or by using a thermochemical cycle. The Born-Haber cycle is an\napplication of Hess\u2019s law that breaks down the formation of an ionic solid into a series of individual steps:\n"]], ["block_11", ["Figure 7.13 diagrams the Born-Haber cycle for the formation of solid cesium fluoride.\n"]], ["block_12", ["\u2022\nthe standard enthalpy of formation of the compound\n"]], ["block_13", ["\u2022\nIE, the ionization energy of the metal\n"]], ["block_14", ["\u2022\nEA, the electron affinity of the nonmetal\n"]], ["block_15", ["\u2022\nthe enthalpy of sublimation of the metal\n"]], ["block_16", ["\u2022\nD, the bond dissociation energy of the nonmetal\n"]], ["block_17", ["\u2022\n\u0394Hlattice, the lattice energy of the compound\n"]], ["block_18", ["EXAMPLE 7.10\n"]], ["block_19", [" 7.5 \u2022 Strengths of Ionic and Covalent Bonds \n 341 \n"]]], "page_355": [["block_0", [" 342 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", [" FIGURE 7.13 \nThe Born-Haber cycle shows the relative energies of each step involved in the formation of an ionic\n"]], ["block_2", ["solid from the necessary elements in their reference states.\n"]], ["block_3", ["We begin with the elements in their most common states, Cs(s) and F2(g). The\nrepresents the conversion\n"]], ["block_4", ["of solid cesium into a gas, and then the ionization energy converts the gaseous cesium atoms into cations. In\nthe next step, we account for the energy required to break the F\u2013F bond to produce fluorine atoms. Converting\none mole of fluorine atoms into fluoride ions is an exothermic process, so this step gives off energy (the\nelectron affinity) and is shown as decreasing along the y-axis. We now have one mole of Cs cations and one\nmole of F anions. These ions combine to produce solid cesium fluoride. The enthalpy change in this step is the\nnegative of the lattice energy, so it is also an exothermic quantity. The total energy involved in this conversion\nis equal to the experimentally determined enthalpy of formation,\nof the compound from its elements. In\n"]], ["block_5", ["this case, the overall change is exothermic.\n"]], ["block_6", ["Hess\u2019s law can also be used to show the relationship between the enthalpies of the individual steps and the\nenthalpy of formation. Table 7.4 shows this for fluoride, CsF.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", ["Enthalpy of\nsublimation of\nCs(s)\n"]], ["block_9", ["One-half of the\nbond energy of\nF2\n"]], ["block_10", ["Ionization\nenergy of Cs(g)\n"]], ["block_11", ["Electron\naffinity of F\n"]], ["block_12", ["Negative of the\nlattice energy\nof CsF(s)\n"]], ["block_13", ["Enthalpy of\nformation of\nCsF(s), add\nsteps 1\u20135\n"]], ["block_14", [{"image_0": "355_0.png", "coords": [130, 57, 481, 247]}]]], "page_356": [["block_0", [" TABLE 7.4 \n"]], ["block_1", ["Thus, the lattice energy can be calculated from other values. For cesium fluoride, using this data, the lattice\nenergy is:\n"]], ["block_2", ["The Born-Haber cycle may also be used to calculate any one of the other quantities in the equation for lattice\nenergy, provided that the remainder is known. For example, if the relevant enthalpy of sublimation\nionization energy (IE), bond dissociation enthalpy (D), lattice energy \u0394Hlattice, and standard enthalpy of\nformation\nare known, the Born-Haber cycle can be used to determine the electron affinity of an atom.\n"]], ["block_3", ["Lattice energies calculated for ionic compounds are typically much higher than bond dissociation energies\nmeasured for covalent bonds. Whereas lattice energies typically fall in the range of 600\u20134000 kJ/mol (some\neven higher), covalent bond dissociation energies are typically between 150\u2013400 kJ/mol for single bonds. Keep\nin mind, however, that these are not directly comparable values. For ionic compounds, lattice energies are\nassociated with many interactions, as cations and anions pack together in an extended lattice. For covalent\nbonds, the bond dissociation energy is associated with the interaction of just two atoms.\n"]], ["block_4", [" 7.6 Molecular Structure and Polarity \n"]], ["block_5", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_6", ["Thus far, we have used two-dimensional Lewis structures to represent molecules. However, molecular\nstructure is actually three-dimensional, and it is important to be able to describe molecular bonds in terms of\ntheir distances, angles, and relative arrangements in space (Figure 7.14). A bond angle is the angle between\nany two bonds that include a common atom, usually measured in degrees. A bond distance (or bond length) is\nthe distance between the nuclei of two bonded atoms along the straight line joining the nuclei. Bond distances\nare measured in \u00c5ngstroms (1 \u00c5 = 10m) or picometers (1 pm = 10m, 100 pm = 1 \u00c5).\n"]], ["block_7", [" VSEPR Theory \n"]], ["block_8", [" Valence shell electron-pair repulsion theory (VSEPR theory) enables us to predict the molecular structure,\nincluding approximate bond angles around a central atom, of a molecule from an examination of the number\nof bonds and lone electron pairs in its Lewis structure. The VSEPR model assumes that electron pairs in the\nvalence shell of a central atom will adopt an arrangement that minimizes repulsions between these electron\npairs by maximizing the distance between them. The electrons in the valence shell of a central atom form\neither bonding pairs of electrons, located primarily between bonded atoms, or lone pairs. The electrostatic\nrepulsion of these electrons is reduced when the various regions of high electron density assume positions as\nfar from each other as possible.\n"]], ["block_9", ["VSEPR theory predicts the arrangement of electron pairs around each central atom and, usually, the correct\n"]], ["block_10", ["\u2022\nPredict the structures of small molecules using valence shell electron pair repulsion (VSEPR) theory\n"]], ["block_11", ["\u2022\nExplain the concepts of polar covalent bonds and molecular polarity\n"]], ["block_12", ["\u2022\nAssess the polarity of a molecule based on its bonding and structure\n"]], ["block_13", [" FIGURE 7.14 \nBond distances (lengths) and angles are shown for the formaldehyde molecule, H2CO.\n"]], ["block_14", [{"image_0": "356_0.png", "coords": [130, 446, 481, 567]}]], ["block_15", [" 7.6 \u2022 Molecular Structure and Polarity \n 343 \n"]]], "page_357": [["block_0", [" 344 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", ["arrangement of atoms in a molecule. We should understand, however, that the theory only considers electron-\npair repulsions. Other interactions, such as nuclear-nuclear repulsions and nuclear-electron attractions, are\nalso involved in the final arrangement that atoms adopt in a particular molecular structure.\n"]], ["block_2", ["As a simple example of VSEPR theory, let us predict the structure of a gaseous BeF2 molecule. The Lewis\nstructure of BeF2 (Figure 7.15) shows only two electron pairs around the central beryllium atom. With two\nbonds and no lone pairs of electrons on the central atom, the bonds are as far apart as possible, and the\nelectrostatic repulsion between these regions of high electron density is reduced to a minimum when they are\non opposite sides of the central atom. The bond angle is 180\u00b0 (Figure 7.15).\n"]], ["block_3", [" FIGURE 7.15 \nThe BeF2 molecule adopts a linear structure in which the two bonds are as far apart as possible, on\n"]], ["block_4", ["opposite sides of the Be atom.\n"]], ["block_5", ["Figure 7.16 illustrates this and other electron-pair geometries that minimize the repulsions among regions of\nhigh electron density (bonds and/or lone pairs). Two regions of electron density around a central atom in a\nmolecule form a linear geometry; three regions form a trigonal planar geometry; four regions form a\n tetrahedral geometry; five regions form a trigonal bipyramidal geometry; and six regions form an octahedral \ngeometry.\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [{"image_0": "357_0.png", "coords": [247, 170, 364, 203]}]]], "page_358": [["block_0", [{"image_0": "358_0.png", "coords": [72, 57, 540, 489]}]], ["block_1", [" FIGURE 7.16 \nThe basic electron-pair geometries predicted by VSEPR theory maximize the space around any\n"]], ["block_2", ["region of electron density (bonds or lone pairs).\n"]], ["block_3", [" Electron-pair Geometry versus Molecular Structure \nIt is important to note that electron-pair geometry around a central atom is not the same thing as its molecular\nstructure. The electron-pair geometries shown in Figure 7.16 describe all regions where electrons are located,\nbonds as well as lone pairs. Molecular structure describes the location of the atoms, not the electrons.\n"]], ["block_4", ["We differentiate between these two situations by naming the geometry that includes all electron pairs the\n electron-pair geometry . The structure that includes only the placement of the atoms in the molecule is called\nthe molecular structure . The electron-pair geometries will be the same as the molecular structures when\nthere are no lone electron pairs around the central atom, but they will be different when there are lone pairs\npresent on the central atom.\n"]], ["block_5", ["For example, the methane molecule, CH4, which is the major component of natural gas, has four bonding pairs\nof electrons around the central carbon atom; the electron-pair geometry is tetrahedral, as is the molecular\nstructure (Figure 7.17). On the other hand, the ammonia molecule, NH3, also has four electron pairs associated\nwith the nitrogen atom, and thus has a tetrahedral electron-pair geometry. One of these regions, however, is a\nlone pair, which is not included in the molecular structure, and this lone pair influences the shape of the\nmolecule (Figure 7.18).\n"]], ["block_6", [" 7.6 \u2022 Molecular Structure and Polarity \n 345 \n"]]], "page_359": [["block_0", [" 346 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", [" FIGURE 7.17 \nThe molecular structure of the methane molecule, CH4, is shown with a tetrahedral arrangement of\n"]], ["block_2", ["the hydrogen atoms. VSEPR structures like this one are often drawn using the wedge and dash notation, in which\nsolid lines represent bonds in the plane of the page, solid wedges represent bonds coming up out of the plane, and\ndashed lines represent bonds going down into the plane.\n"]], ["block_3", [" FIGURE 7.18 \n(a) The electron-pair geometry for the ammonia molecule is tetrahedral with one lone pair and three\n"]], ["block_4", ["single bonds. (b) The trigonal pyramidal molecular structure is determined from the electron-pair geometry. (c) The\nactual bond angles deviate slightly from the idealized angles because the lone pair takes up a larger region of space\nthan do the single bonds, causing the HNH angle to be slightly smaller than 109.5\u00b0.\n"]], ["block_5", ["As seen in Figure 7.18, small distortions from the ideal angles in Figure 7.16 can result from differences in\nrepulsion between various regions of electron density. VSEPR theory predicts these distortions by establishing\nan order of repulsions and an order of the amount of space occupied by different kinds of electron pairs. The\norder of electron-pair repulsions from greatest to least repulsion is:\n"]], ["block_6", ["This order of repulsions determines the amount of space occupied by different regions of electrons. A lone pair\nof electrons occupies a larger region of space than the electrons in a triple bond; in turn, electrons in a triple\nbond occupy more space than those in a double bond, and so on. The order of sizes from largest to smallest is:\n"]], ["block_7", ["Consider formaldehyde, H2CO, which is used as a preservative for biological and anatomical specimens (Figure\n7.14). This molecule has regions of high electron density that consist of two single bonds and one double bond.\nThe basic geometry is trigonal planar with 120\u00b0 bond angles, but we see that the double bond causes slightly\nlarger angles (121\u00b0), and the angle between the single bonds is slightly smaller (118\u00b0).\n"]], ["block_8", ["In the ammonia molecule, the three hydrogen atoms attached to the central nitrogen are not arranged in a flat,\ntrigonal planar molecular structure, but rather in a three-dimensional trigonal pyramid (Figure 7.18) with the\nnitrogen atom at the apex and the three hydrogen atoms forming the base. The ideal bond angles in a trigonal\npyramid are based on the tetrahedral electron pair geometry. Again, there are slight deviations from the ideal\nbecause lone pairs occupy larger regions of space than do bonding electrons. The H\u2013N\u2013H bond angles in NH3\nare slightly smaller than the 109.5\u00b0 angle in a regular tetrahedron (Figure 7.16) because the lone pair-bonding\npair repulsion is greater than the bonding pair-bonding pair repulsion (Figure 7.18). Figure 7.19 illustrates the\nideal molecular structures, which are predicted based on the electron-pair geometries for various\ncombinations of lone pairs and bonding pairs.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", [{"image_0": "359_0.png", "coords": [130, 163, 481, 268]}]], ["block_11", [{"image_1": "359_1.png", "coords": [281, 57, 330, 103]}]]], "page_360": [["block_0", [{"image_0": "360_0.png", "coords": [72, 57, 540, 448]}]], ["block_1", [" FIGURE 7.19 \nThe molecular structures are identical to the electron-pair geometries when there are no lone pairs\n"]], ["block_2", ["present (first column). For a particular number of electron pairs (row), the molecular structures for one or more lone\npairs are determined based on modifications of the corresponding electron-pair geometry.\n"]], ["block_3", ["According to VSEPR theory, the terminal atom locations (Xs in Figure 7.19) are equivalent within the linear,\ntrigonal planar, and tetrahedral electron-pair geometries (the first three rows of the table). It does not matter\nwhich X is replaced with a lone pair because the molecules can be rotated to convert positions. For trigonal\nbipyramidal electron-pair geometries, however, there are two distinct X positions, as shown in Figure 7.20: an\n axial position (if we hold a model of a trigonal bipyramid by the two axial positions, we have an axis around\nwhich we can rotate the model) and an equatorial position (three positions form an equator around the\nmiddle of the molecule). As shown in Figure 7.19, the axial position is surrounded by bond angles of 90\u00b0,\nwhereas the equatorial position has more space available because of the 120\u00b0 bond angles. In a trigonal\nbipyramidal electron-pair geometry, lone pairs always occupy equatorial positions because these more\nspacious positions can more easily accommodate the larger lone pairs.\n"]], ["block_4", ["Theoretically, we can come up with three possible arrangements for the three bonds and two lone pairs for the\nClF3 molecule (Figure 7.20). The stable structure is the one that puts the lone pairs in equatorial locations,\ngiving a T-shaped molecular structure.\n"]], ["block_5", [" 7.6 \u2022 Molecular Structure and Polarity \n 347 \n"]]], "page_361": [["block_0", [" 348 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", [{"image_0": "361_0.png", "coords": [72, 57, 540, 174]}]], ["block_2", [" FIGURE 7.20 \n(a) In a trigonal bipyramid, the two axial positions are located directly across from one another,\n"]], ["block_3", ["whereas the three equatorial positions are located in a triangular arrangement. (b\u2013d) The two lone pairs (red lines)\nin ClF3 have several possible arrangements, but the T-shaped molecular structure (b) is the one actually observed,\nconsistent with the larger lone pairs both occupying equatorial positions.\n"]], ["block_4", ["When a central atom has two lone electron pairs and four bonding regions, we have an octahedral electron-\npair geometry. The two lone pairs are on opposite sides of the octahedron (180\u00b0 apart), giving a square planar\nmolecular structure that minimizes lone pair-lone pair repulsions (Figure 7.19).\n"]], ["block_5", [" Predicting Electron Pair Geometry and Molecular Structure \nThe following procedure uses VSEPR theory to determine the electron pair geometries and the molecular\nstructures:\n"]], ["block_6", ["The following examples illustrate the use of VSEPR theory to predict the molecular structure of molecules or\nions that have no lone pairs of electrons. In this case, the molecular structure is identical to the electron pair\ngeometry.\n"]], ["block_7", [" Predicting Electron-pair Geometry and Molecular Structure: CO 2 and BCl 3 \nPredict the electron-pair geometry and molecular structure for each of the following:\n"]], ["block_8", ["(a) carbon dioxide, CO2, a molecule produced by the combustion of fossil fuels\n"]], ["block_9", ["(b) boron trichloride, BCl3, an important industrial chemical\n"]], ["block_10", [" Solution \n"]], ["block_11", ["(a) We write the Lewis structure of CO2 as:\n"]], ["block_12", [{"image_1": "361_1.png", "coords": [72, 651, 124, 674]}]], ["block_13", ["This shows us two regions of high electron density around the carbon atom\u2014each double bond counts as one\nregion, and there are no lone pairs on the carbon atom. Using VSEPR theory, we predict that the two regions of\nelectron density arrange themselves on opposite sides of the central atom with a bond angle of 180\u00b0. The\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["1.\nWrite the Lewis structure of the molecule or polyatomic ion.\n"]], ["block_16", ["2.\nCount the number of regions of electron density (lone pairs and bonds) around the central atom. A single,\ndouble, or triple bond counts as one region of electron density.\n"]], ["block_17", ["3.\nIdentify the electron-pair geometry based on the number of regions of electron density: linear, trigonal\nplanar, tetrahedral, trigonal bipyramidal, or octahedral (Figure 7.19, first column).\n"]], ["block_18", ["4.\nUse the number of lone pairs to determine the molecular structure (Figure 7.19). If more than one\narrangement of lone pairs and chemical bonds is possible, choose the one that will minimize repulsions,\nremembering that lone pairs occupy more space than multiple bonds, which occupy more space than\nsingle bonds. In trigonal bipyramidal arrangements, repulsion is minimized when every lone pair is in an\nequatorial position. In an octahedral arrangement with two lone pairs, repulsion is minimized when the\nlone pairs are on opposite sides of the central atom.\n"]], ["block_19", ["EXAMPLE 7.11\n"]]], "page_362": [["block_0", ["electron-pair geometry and molecular structure are identical, and CO2 molecules are linear.\n"]], ["block_1", ["(b) We write the Lewis structure of BCl3 as:\n"]], ["block_2", [{"image_0": "362_0.png", "coords": [72, 95, 135, 137]}]], ["block_3", ["Thus we see that BCl3 contains three bonds, and there are no lone pairs of electrons on boron. The\narrangement of three regions of high electron density gives a trigonal planar electron-pair geometry. The B\u2013Cl\nbonds lie in a plane with 120\u00b0 angles between them. BCl3 also has a trigonal planar molecular structure (Figure\n7.21).\n"]], ["block_4", ["The electron-pair geometry and molecular structure of BCl3 are both trigonal planar. Note that the VSEPR\ngeometry indicates the correct bond angles (120\u00b0), unlike the Lewis structure shown above.\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["Carbonate,\nis a common polyatomic ion found in various materials from eggshells to antacids. What\n"]], ["block_7", ["are the electron-pair geometry and molecular structure of this polyatomic ion?\n"]], ["block_8", [" Answer: \nThe electron-pair geometry is trigonal planar and the molecular structure is trigonal planar. Due to resonance,\nall three C\u2013O bonds are identical. Whether they are single, double, or an average of the two, each bond counts\nas one region of electron density.\n"]], ["block_9", [" Predicting Electron-pair Geometry and Molecular Structure: Ammonium \n"]], ["block_10", ["Two of the top 50 chemicals produced in the United States, ammonium nitrate and ammonium sulfate, both\nused as fertilizers, contain the ammonium ion. Predict the electron-pair geometry and molecular structure of\nthe\ncation.\n"]], ["block_11", [" Solution \n"]], ["block_12", ["We write the Lewis structure of\nas:\n"]], ["block_13", [{"image_1": "362_1.png", "coords": [72, 532, 143, 596]}]], ["block_14", ["We can see that\ncontains four bonds from the nitrogen atom to hydrogen atoms and no lone pairs. We\n"]], ["block_15", ["expect the four regions of high electron density to arrange themselves so that they point to the corners of a\ntetrahedron with the central nitrogen atom in the middle (Figure 7.19). Therefore, the electron pair geometry\nof\nis tetrahedral, and the molecular structure is also tetrahedral (Figure 7.22).\n"]], ["block_16", ["EXAMPLE 7.12\n"]], ["block_17", [" FIGURE 7.21 \n"]], ["block_18", [{"image_2": "362_2.png", "coords": [280, 197, 331, 231]}]], ["block_19", [" 7.6 \u2022 Molecular Structure and Polarity \n 349 \n"]]], "page_363": [["block_0", [" 350 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", [" FIGURE 7.22 \nThe ammonium ion displays a tetrahedral electron-pair geometry as well as a tetrahedral molecular\n"]], ["block_2", ["structure.\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["Identify a molecule with trigonal bipyramidal molecular structure.\n"]], ["block_5", [" Answer: \nAny molecule with five electron pairs around the central atoms including no lone pairs will be trigonal\nbipyramidal. PF5 is a common example.\n"]], ["block_6", ["The next several examples illustrate the effect of lone pairs of electrons on molecular structure.\n"]], ["block_7", [" Predicting Electron-pair Geometry and Molecular Structure: Lone Pairs on the Central Atom \n"]], ["block_8", ["Predict the electron-pair geometry and molecular structure of a water molecule.\n"]], ["block_9", [" Solution \n"]], ["block_10", ["The Lewis structure of H2O indicates that there are four regions of high electron density around the oxygen\natom: two lone pairs and two chemical bonds:\n"]], ["block_11", [{"image_0": "363_0.png", "coords": [72, 381, 108, 419]}]], ["block_12", ["We predict that these four regions are arranged in a tetrahedral fashion (Figure 7.23), as indicated in Figure\n7.19. Thus, the electron-pair geometry is tetrahedral and the molecular structure is bent with an angle slightly\nless than 109.5\u00b0. In fact, the bond angle is 104.5\u00b0.\n"]], ["block_13", [" FIGURE 7.23 \n(a) H2O has four regions of electron density around the central atom, so it has a tetrahedral electron-\n"]], ["block_14", ["pair geometry. (b) Two of the electron regions are lone pairs, so the molecular structure is bent.\n"]], ["block_15", [" Check Your Learning \n"]], ["block_16", ["The hydronium ion, H3O, forms when acids are dissolved in water. Predict the electron-pair geometry and\nmolecular structure of this cation.\n"]], ["block_17", [" Answer: \nelectron pair geometry: tetrahedral; molecular structure: trigonal pyramidal\n"]], ["block_18", [" Access for free at openstax.org \n"]], ["block_19", ["EXAMPLE 7.13\n"]], ["block_20", [{"image_1": "363_1.png", "coords": [189, 466, 423, 587]}]], ["block_21", [{"image_2": "363_2.png", "coords": [272, 57, 339, 118]}]]], "page_364": [["block_0", [" Predicting Electron-pair Geometry and Molecular Structure: SF 4 \nSulfur tetrafluoride, SF4, is extremely valuable for the preparation of fluorine-containing compounds used as\nherbicides (i.e., SF4 is used as a fluorinating agent). Predict the electron-pair geometry and molecular\nstructure of a SF4 molecule.\n"]], ["block_1", [" Solution \n"]], ["block_2", ["The Lewis structure of SF4 indicates five regions of electron density around the sulfur atom: one lone pair and\nfour bonding pairs:\n"]], ["block_3", [{"image_0": "364_0.png", "coords": [72, 197, 110, 259]}]], ["block_4", ["We expect these five regions to adopt a trigonal bipyramidal electron-pair geometry. To minimize lone pair\nrepulsions, the lone pair occupies one of the equatorial positions. The molecular structure (Figure 7.24) is that\nof a seesaw (Figure 7.19).\n"]], ["block_5", [" FIGURE 7.24 \n(a) SF4 has a trigonal bipyramidal arrangement of the five regions of electron density. (b) One of the\n"]], ["block_6", ["regions is a lone pair, which results in a seesaw-shaped molecular structure.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["Predict the electron pair geometry and molecular structure for molecules of XeF2.\n"]], ["block_9", [" Answer: \nThe electron-pair geometry is trigonal bipyramidal. The molecular structure is linear.\n"]], ["block_10", [" Predicting Electron-pair Geometry and Molecular Structure: XeF 4 \nOf all the noble gases, xenon is the most reactive, frequently reacting with elements such as oxygen and\nfluorine. Predict the electron-pair geometry and molecular structure of the XeF4 molecule.\n"]], ["block_11", [" Solution \n"]], ["block_12", ["The Lewis structure of XeF4 indicates six regions of high electron density around the xenon atom: two lone\npairs and four bonds:\n"]], ["block_13", ["EXAMPLE 7.14\n"]], ["block_14", ["EXAMPLE 7.15\n"]], ["block_15", [{"image_1": "364_1.png", "coords": [189, 306, 423, 445]}]], ["block_16", [" 7.6 \u2022 Molecular Structure and Polarity \n 351 \n"]]], "page_365": [["block_0", [" 352 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", [{"image_0": "365_0.png", "coords": [72, 57, 132, 115]}]], ["block_2", ["These six regions adopt an octahedral arrangement (Figure 7.19), which is the electron-pair geometry. To\nminimize repulsions, the lone pairs should be on opposite sides of the central atom (Figure 7.25). The five\natoms are all in the same plane and have a square planar molecular structure.\n"]], ["block_3", [" FIGURE 7.25 \n(a) XeF4 adopts an octahedral arrangement with two lone pairs (red lines) and four bonds in the\n"]], ["block_4", ["electron-pair geometry. (b) The molecular structure is square planar with the lone pairs directly across from one\nanother.\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["In a certain molecule, the central atom has three lone pairs and two bonds. What will the electron pair\ngeometry and molecular structure be?\n"]], ["block_7", [" Answer: \nelectron pair geometry: trigonal bipyramidal; molecular structure: linear\n"]], ["block_8", [" Molecular Structure for Multicenter Molecules \nWhen a molecule or polyatomic ion has only one central atom, the molecular structure completely describes\nthe shape of the molecule. Larger molecules do not have a single central atom, but are connected by a chain of\ninterior atoms that each possess a \u201clocal\u201d geometry. The way these local structures are oriented with respect to\neach other also influences the molecular shape, but such considerations are largely beyond the scope of this\nintroductory discussion. For our purposes, we will only focus on determining the local structures.\n"]], ["block_9", [" Predicting Structure in Multicenter Molecules \n"]], ["block_10", ["The Lewis structure for the simplest amino acid, glycine, H2NCH2CO2H, is shown here. Predict the local\ngeometry for the nitrogen atom, the two carbon atoms, and the oxygen atom with a hydrogen atom attached:\n"]], ["block_11", [{"image_1": "365_1.png", "coords": [72, 575, 183, 628]}]], ["block_12", [" Solution \n"]], ["block_13", [{"image_2": "365_2.png", "coords": [72, 651, 160, 713]}]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["EXAMPLE 7.16\n"]], ["block_16", [{"image_3": "365_3.png", "coords": [189, 162, 423, 270]}]]], "page_366": [["block_0", ["Consider each central atom independently. The electron-pair geometries:\n"]], ["block_1", ["The local structures:\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["Another amino acid is alanine, which has the Lewis structure shown here. Predict the electron-pair geometry\nand local structure of the nitrogen atom, the three carbon atoms, and the oxygen atom with hydrogen attached:\n"]], ["block_4", [{"image_0": "366_0.png", "coords": [72, 255, 194, 312]}]], ["block_5", [" Answer: \nelectron-pair geometries: nitrogen\u2013\u2013tetrahedral; carbon (CH)\u2014tetrahedral; carbon (CH3)\u2014tetrahedral; carbon\n(CO2)\u2014trigonal planar; oxygen (OH)\u2014tetrahedral; local structures: nitrogen\u2014trigonal pyramidal; carbon\n(CH)\u2014tetrahedral; carbon (CH3)\u2014tetrahedral; carbon (CO2)\u2014trigonal planar; oxygen (OH)\u2014bent (109\u00b0)\n"]], ["block_6", ["The molecular shape simulator (http://openstax.org/l/16MolecShape) lets you build various molecules and\npractice naming their electron-pair geometries and molecular structures.\n"]], ["block_7", [" Molecular Simulation \n"]], ["block_8", ["Using molecular shape simulator (http://openstax.org/l/16MolecShape) allows us to control whether bond\nangles and/or lone pairs are displayed by checking or unchecking the boxes under \u201cOptions\u201d on the right. We\ncan also use the \u201cName\u201d checkboxes at bottom-left to display or hide the electron pair geometry (called\n\u201celectron geometry\u201d in the simulator) and/or molecular structure (called \u201cmolecular shape\u201d in the simulator).\n"]], ["block_9", ["Build the molecule HCN in the simulator based on the following Lewis structure:\n"]], ["block_10", ["Click on each bond type or lone pair at right to add that group to the central atom. Once you have the complete\nmolecule, rotate it to examine the predicted molecular structure. What molecular structure is this?\n"]], ["block_11", [" Solution \n"]], ["block_12", ["The molecular structure is linear.\n"]], ["block_13", [" Check Your Learning \n"]], ["block_14", ["Build a more complex molecule in the simulator. Identify the electron-group geometry, molecular structure,\nand bond angles. Then try to find a chemical formula that would match the structure you have drawn.\n"]], ["block_15", ["\u2022\nnitrogen\u2013\u2013four regions of electron density; tetrahedral\n"]], ["block_16", ["\u2022\ncarbon (CH2)\u2013\u2013four regions of electron density; tetrahedral\n"]], ["block_17", ["\u2022\ncarbon (CO2)\u2014three regions of electron density; trigonal planar\n"]], ["block_18", ["\u2022\noxygen (OH)\u2014four regions of electron density; tetrahedral\n"]], ["block_19", ["\u2022\nnitrogen\u2013\u2013three bonds, one lone pair; trigonal pyramidal\n"]], ["block_20", ["\u2022\ncarbon (CH2)\u2014four bonds, no lone pairs; tetrahedral\n"]], ["block_21", ["\u2022\ncarbon (CO2)\u2014three bonds (double bond counts as one bond), no lone pairs; trigonal planar\n"]], ["block_22", ["\u2022\noxygen (OH)\u2014two bonds, two lone pairs; bent (109\u00b0)\n"]], ["block_23", ["LINK TO LEARNING\n"]], ["block_24", ["EXAMPLE 7.17\n"]], ["block_25", [" 7.6 \u2022 Molecular Structure and Polarity \n 353 \n"]]], "page_367": [["block_0", [" 354 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", [" Answer: \nAnswers will vary. For example, an atom with four single bonds, a double bond, and a lone pair has an\noctahedral electron-group geometry and a square pyramidal molecular structure. XeOF4 is a molecule that\nadopts this structure.\n"]], ["block_2", [" Molecular Polarity and Dipole Moment \n"]], ["block_3", ["As discussed previously, polar covalent bonds connect two atoms with differing electronegativities, leaving one\natom with a partial positive charge (\u03b4+) and the other atom with a partial negative charge (\u03b4\u2013), as the electrons\nare pulled toward the more electronegative atom. This separation of charge gives rise to a bond dipole \n moment . The magnitude of a bond dipole moment is represented by the Greek letter mu (\u00b5) and is given by the\nformula shown here, where Q is the magnitude of the partial charges (determined by the electronegativity\ndifference) and r is the distance between the charges:\n"]], ["block_4", ["This bond moment can be represented as a vector , a quantity having both direction and magnitude (Figure\n7.26). Dipole vectors are shown as arrows pointing along the bond from the less electronegative atom toward\nthe more electronegative atom. A small plus sign is drawn on the less electronegative end to indicate the\npartially positive end of the bond. The length of the arrow is proportional to the magnitude of the\nelectronegativity difference between the two atoms.\n"]], ["block_5", [" FIGURE 7.26 \n(a) There is a small difference in electronegativity between C and H, represented as a short vector.\n"]], ["block_6", ["(b) The electronegativity difference between B and F is much larger, so the vector representing the bond moment is\nmuch longer.\n"]], ["block_7", ["A whole molecule may also have a separation of charge, depending on its molecular structure and the polarity\nof each of its bonds. If such a charge separation exists, the molecule is said to be a polar molecule (or dipole);\notherwise the molecule is said to be nonpolar. The dipole moment measures the extent of net charge\nseparation in the molecule as a whole. We determine the dipole moment by adding the bond moments in\nthree-dimensional space, taking into account the molecular structure.\n"]], ["block_8", ["For diatomic molecules, there is only one bond, so its bond dipole moment determines the molecular polarity.\nHomonuclear diatomic molecules such as Br2 and N2 have no difference in electronegativity, so their dipole\nmoment is zero. For heteronuclear molecules such as CO, there is a small dipole moment. For HF, there is a\nlarger dipole moment because there is a larger difference in electronegativity.\n"]], ["block_9", ["When a molecule contains more than one bond, the geometry must be taken into account. If the bonds in a\nmolecule are arranged such that their bond moments cancel (vector sum equals zero), then the molecule is\nnonpolar. This is the situation in CO2 (Figure 7.27). Each of the bonds is polar, but the molecule as a whole is\nnonpolar. From the Lewis structure, and using VSEPR theory, we determine that the CO2 molecule is linear\nwith polar C=O bonds on opposite sides of the carbon atom. The bond moments cancel because they are\npointed in opposite directions. In the case of the water molecule (Figure 7.27), the Lewis structure again shows\nthat there are two bonds to a central atom, and the electronegativity difference again shows that each of these\nbonds has a nonzero bond moment. In this case, however, the molecular structure is bent because of the lone\npairs on O, and the two bond moments do not cancel. Therefore, water does have a net dipole moment and is a\npolar molecule (dipole).\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [{"image_0": "367_0.png", "coords": [189, 318, 423, 380]}]]], "page_368": [["block_0", [" FIGURE 7.27 \nThe overall dipole moment of a molecule depends on the individual bond dipole moments and how\n"]], ["block_1", ["they are arranged. (a) Each CO bond has a bond dipole moment, but they point in opposite directions so that the net\nCO2 molecule is nonpolar. (b) In contrast, water is polar because the OH bond moments do not cancel out.\n"]], ["block_2", ["The OCS molecule has a structure similar to CO2, but a sulfur atom has replaced one of the oxygen atoms. To\ndetermine if this molecule is polar, we draw the molecular structure. VSEPR theory predicts a linear molecule:\n"]], ["block_3", [{"image_0": "368_0.png", "coords": [72, 278, 189, 358]}]], ["block_4", ["The C-O bond is considerably polar. Although C and S have very similar electronegativity values, S is slightly\nmore electronegative than C, and so the C-S bond is just slightly polar. Because oxygen is more electronegative\nthan sulfur, the oxygen end of the molecule is the negative end.\n"]], ["block_5", ["Chloromethane, CH3Cl, is a tetrahedral molecule with three slightly polar C-H bonds and a more polar C-Cl\nbond. The relative electronegativities of the bonded atoms is H < C < Cl, and so the bond moments all point\ntoward the Cl end of the molecule and sum to yield a considerable dipole moment (the molecules are relatively\npolar).\n"]], ["block_6", [{"image_1": "368_1.png", "coords": [72, 462, 189, 512]}]], ["block_7", ["For molecules of high symmetry such as BF3 (trigonal planar), CH4 (tetrahedral), PF5 (trigonal bipyramidal),\nand SF6 (octahedral), all the bonds are of identical polarity (same bond moment) and they are oriented in\ngeometries that yield nonpolar molecules (dipole moment is zero). Molecules of less geometric symmetry,\nhowever, may be polar even when all bond moments are identical. For these molecules, the directions of the\nequal bond moments are such that they sum to give a nonzero dipole moment and a polar molecule. Examples\nof such molecules include hydrogen sulfide, H2S (nonlinear), and ammonia, NH3 (trigonal pyramidal).\n"]], ["block_8", [{"image_2": "368_2.png", "coords": [72, 597, 306, 642]}]], ["block_9", ["To summarize, to be polar, a molecule must:\n"]], ["block_10", [" Properties of Polar Molecules \nPolar molecules tend to align when placed in an electric field with the positive end of the molecule oriented\n"]], ["block_11", ["1.\nContain at least one polar covalent bond.\n"]], ["block_12", ["2.\nHave a molecular structure such that the sum of the vectors of each bond dipole moment does not cancel.\n"]], ["block_13", [{"image_3": "368_3.png", "coords": [189, 57, 423, 200]}]], ["block_14", [" 7.6 \u2022 Molecular Structure and Polarity \n 355 \n"]]], "page_369": [["block_0", [" 356 \n 7 \u2022 Chemical Bonding and Molecular Geometry \n"]], ["block_1", ["toward the negative plate and the negative end toward the positive plate (Figure 7.28). We can use an\nelectrically charged object to attract polar molecules, but nonpolar molecules are not attracted. Also, polar\nsolvents are better at dissolving polar substances, and nonpolar solvents are better at dissolving nonpolar\nsubstances.\n"]], ["block_2", [{"image_0": "369_0.png", "coords": [72, 114, 540, 401]}]], ["block_3", [" FIGURE 7.28 \n(a) Molecules are always randomly distributed in the liquid state in the absence of an electric field.\n"]], ["block_4", ["(b) When an electric field is applied, polar molecules like HF will align to the dipoles with the field direction.\n"]], ["block_5", ["The molecule polarity simulation (http://openstax.org/l/16MolecPolarity) provides many ways to explore dipole\nmoments of bonds and molecules.\n"]], ["block_6", [" Polarity Simulations \n"]], ["block_7", ["Open the molecule polarity simulation (http://openstax.org/l/16MolecPolarity) and select the \u201cThree Atoms\u201d\ntab at the top. This should display a molecule ABC with three electronegativity adjustors. You can display or\nhide the bond moments, molecular dipoles, and partial charges at the right. Turning on the Electric Field will\nshow whether the molecule moves when exposed to a field, similar to Figure 7.28.\n"]], ["block_8", ["Use the electronegativity controls to determine how the molecular dipole will look for the starting bent\nmolecule if:\n"]], ["block_9", ["(a) A and C are very electronegative and B is in the middle of the range.\n"]], ["block_10", ["(b) A is very electronegative, and B and C are not.\n"]], ["block_11", [" Solution \n"]], ["block_12", ["(a) Molecular dipole moment points immediately between A and C.\n"]], ["block_13", ["(b) Molecular dipole moment points along the A\u2013B bond, toward A.\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["LINK TO LEARNING\n"]], ["block_16", ["EXAMPLE 7.18\n"]]], "page_370": [["block_0", [" Check Your Learning \n"]], ["block_1", ["Determine the partial charges that will give the largest possible bond dipoles.\n"]], ["block_2", [" Answer: \nThe largest bond moments will occur with the largest partial charges. The two solutions above represent how\nunevenly the electrons are shared in the bond. The bond moments will be maximized when the\nelectronegativity difference is greatest. The controls for A and C should be set to one extreme, and B should be\nset to the opposite extreme. Although the magnitude of the bond moment will not change based on whether B\nis the most electronegative or the least, the direction of the bond moment will.\n"]], ["block_3", [" 7.6 \u2022 Molecular Structure and Polarity \n 357 \n"]]], "page_371": [["block_0", [" 358 \n 7 \u2022 Key Terms \n"]], ["block_1", [" Key Terms \n"]], ["block_2", [" axial position \nlocation in a trigonal bipyramidal\n"]], ["block_3", [" bond angle \nangle between any two covalent bonds\n"]], ["block_4", [" bond dipole moment \nseparation of charge in a\n"]], ["block_5", [" bond distance \n(also, bond length) distance\n"]], ["block_6", [" bond energy \n(also, bond dissociation energy)\n"]], ["block_7", [" bond length \ndistance between the nuclei of two\n"]], ["block_8", [" Born-Haber cycle \nthermochemical cycle relating\n"]], ["block_9", [" covalent bond \nbond formed when electrons are\n"]], ["block_10", [" dipole moment \nproperty of a molecule that\n"]], ["block_11", [" double bond \ncovalent bond in which two pairs of\n"]], ["block_12", [" electron-pair geometry \narrangement around a\n"]], ["block_13", [" electronegativity \ntendency of an atom to attract\n"]], ["block_14", [" equatorial position \none of the three positions in a\n"]], ["block_15", [" formal charge \ncharge that would result on an atom\n"]], ["block_16", [" free radical \nmolecule that contains an odd number\n"]], ["block_17", [" hypervalent molecule \nmolecule containing at\n"]], ["block_18", [" inert pair effect \ntendency of heavy atoms to form\n"]], ["block_19", [" ionic bond \nstrong electrostatic force of attraction\n"]], ["block_20", [" Access for free at openstax.org \n"]], ["block_21", ["geometry in which there is another atom at a\n180\u00b0 angle and the equatorial positions are at a\n90\u00b0 angle\n"]], ["block_22", ["that share a common atom\n"]], ["block_23", ["bond that depends on the difference in\nelectronegativity and the bond distance\nrepresented by partial charges or a vector\n"]], ["block_24", ["between the nuclei of two bonded atoms\n"]], ["block_25", ["energy required to break a covalent bond in a\ngaseous substance\n"]], ["block_26", ["bonded atoms at which the lowest potential\nenergy is achieved\n"]], ["block_27", ["the various energetic steps involved in the\nformation of an ionic solid from the relevant\nelements\n"]], ["block_28", ["shared between atoms\n"]], ["block_29", ["describes the separation of charge determined by\nthe sum of the individual bond moments based\non the molecular structure\n"]], ["block_30", ["electrons are shared between two atoms\n"]], ["block_31", ["central atom of all regions of electron density\n(bonds, lone pairs, or unpaired electrons)\n"]], ["block_32", ["electrons in a bond to itself\n"]], ["block_33", ["trigonal bipyramidal geometry with 120\u00b0 angles\nbetween them; the axial positions are located at a\n90\u00b0 angle\n"]], ["block_34", ["by taking the number of valence electrons on the\nneutral atom and subtracting the nonbonding\nelectrons and the number of bonds (one-half of\nthe bonding electrons)\n"]], ["block_35", ["of electrons\n"]], ["block_36", ["least one main group element that has more than\neight electrons in its valence shell\n"]], ["block_37", ["ions in which their valence s electrons are not lost\n"]], ["block_38", [" lattice energy ( \u0394 H lattice ) \nenergy required to\n"]], ["block_39", [" Lewis structure \ndiagram showing lone pairs and\n"]], ["block_40", [" Lewis symbol \nsymbol for an element or\n"]], ["block_41", [" linear \nshape in which two outside groups are\n"]], ["block_42", [" lone pair \ntwo (a pair of) valence electrons that are\n"]], ["block_43", [" molecular structure \narrangement of atoms in a\n"]], ["block_44", [" molecular structure \nstructure that includes only\n"]], ["block_45", [" octahedral \nshape in which six outside groups are\n"]], ["block_46", [" octet rule \nguideline that states main group atoms\n"]], ["block_47", [" polar covalent bond \ncovalent bond between atoms\n"]], ["block_48", [" polar molecule \n(also, dipole) molecule with an\n"]], ["block_49", [" pure covalent bond \n(also, nonpolar covalent bond)\n"]], ["block_50", [" resonance \nsituation in which one Lewis structure\n"]], ["block_51", [" resonance forms \ntwo or more Lewis structures\n"]], ["block_52", [" resonance hybrid \naverage of the resonance forms\n"]], ["block_53", [" single bond \nbond in which a single pair of\n"]], ["block_54", [" tetrahedral \nshape in which four outside groups are\n"]], ["block_55", ["between cations and anions in an ionic\ncompound\n"]], ["block_56", ["separate one mole of an ionic solid into its\ncomponent gaseous ions\n"]], ["block_57", ["bonding pairs of electrons in a molecule or an ion\n"]], ["block_58", ["monatomic ion that uses a dot to represent each\nvalence electron in the element or ion\n"]], ["block_59", ["placed on opposite sides of a central atom\n"]], ["block_60", ["not used to form a covalent bond\n"]], ["block_61", ["molecule or ion\n"]], ["block_62", ["the placement of the atoms in the molecule\n"]], ["block_63", ["placed around a central atom such that a three-\ndimensional shape is generated with four groups\nforming a square and the other two forming the\napex of two pyramids, one above and one below\nthe square plane\n"]], ["block_64", ["will form structures in which eight valence\nelectrons interact with each nucleus, counting\nbonding electrons as interacting with both atoms\nconnected by the bond\n"]], ["block_65", ["of different electronegativities; a covalent bond\nwith a positive end and a negative end\n"]], ["block_66", ["overall dipole moment\n"]], ["block_67", ["covalent bond between atoms of identical\nelectronegativities\n"]], ["block_68", ["is insufficient to describe the bonding in a\nmolecule and the average of multiple structures\nis observed\n"]], ["block_69", ["that have the same arrangement of atoms but\ndifferent arrangements of electrons\n"]], ["block_70", ["shown by the individual Lewis structures\n"]], ["block_71", ["electrons is shared between two atoms\n"]], ["block_72", ["placed around a central atom such that a three-\ndimensional shape is generated with four corners\nand 109.5\u00b0 angles between each pair and the\n"]]], "page_372": [["block_0", [" trigonal bipyramidal \nshape in which five outside\n"]], ["block_1", [" trigonal planar \nshape in which three outside\n"]], ["block_2", [" Key Equations \n"]], ["block_3", [" Summary \n"]], ["block_4", [" 7.1 Ionic Bonding \n"]], ["block_5", ["Atoms gain or lose electrons to form ions with\nparticularly stable electron configurations. The\ncharges of cations formed by the representative\nmetals may be determined readily because, with few\nexceptions, the electronic structures of these ions\nhave either a noble gas configuration or a completely\nfilled electron shell. The charges of anions formed\nby the nonmetals may also be readily determined\nbecause these ions form when nonmetal atoms gain\nenough electrons to fill their valence shells.\n"]], ["block_6", [" 7.2 Covalent Bonding \n"]], ["block_7", ["Covalent bonds form when electrons are shared\nbetween atoms and are attracted by the nuclei of\nboth atoms. In pure covalent bonds, the electrons\nare shared equally. In polar covalent bonds, the\nelectrons are shared unequally, as one atom exerts a\nstronger force of attraction on the electrons than the\nother. The ability of an atom to attract a pair of\nelectrons in a chemical bond is called its\nelectronegativity. The difference in electronegativity\nbetween two atoms determines how polar a bond\nwill be. In a diatomic molecule with two identical\natoms, there is no difference in electronegativity, so\nthe bond is nonpolar or pure covalent. When the\nelectronegativity difference is very large, as is the\ncase between metals and nonmetals, the bonding is\ncharacterized as ionic.\n"]], ["block_8", ["Bond energy for a diatomic molecule:\n"]], ["block_9", ["Enthalpy change: \u0394H = \u01a9Dbonds broken \u2013 \u01a9Dbonds formed\nLattice energy for a solid MX:\n"]], ["block_10", ["Lattice energy for an ionic crystal:\n"]], ["block_11", ["central atom\n"]], ["block_12", ["groups are placed around a central atom such\nthat three form a flat triangle with 120\u00b0 angles\nbetween each pair and the central atom, and the\nother two form the apex of two pyramids, one\nabove and one below the triangular plane\n"]], ["block_13", ["groups are placed in a flat triangle around a\ncentral atom with 120\u00b0 angles between each pair\n"]], ["block_14", [" triple bond \nbond in which three pairs of electrons\n"]], ["block_15", [" valence shell electron-pair repulsion theory \n"]], ["block_16", [" vector \nquantity having magnitude and direction\n"]], ["block_17", [" 7.3 Lewis Symbols and Structures \n"]], ["block_18", ["Valence electronic structures can be visualized by\ndrawing Lewis symbols (for atoms and monatomic\nions) and Lewis structures (for molecules and\npolyatomic ions). Lone pairs, unpaired electrons,\nand single, double, or triple bonds are used to\nindicate where the valence electrons are located\naround each atom in a Lewis structure. Most\nstructures\u2014especially those containing second row\nelements\u2014obey the octet rule, in which every atom\n(except H) is surrounded by eight electrons.\nExceptions to the octet rule occur for odd-electron\nmolecules (free radicals), electron-deficient\nmolecules, and hypervalent molecules.\n"]], ["block_19", [" 7.4 Formal Charges and Resonance \n"]], ["block_20", ["In a Lewis structure, formal charges can be assigned\nto each atom by treating each bond as if one-half of\nthe electrons are assigned to each atom. These\nhypothetical formal charges are a guide to\ndetermining the most appropriate Lewis structure. A\nstructure in which the formal charges are as close to\nzero as possible is preferred. Resonance occurs in\ncases where two or more Lewis structures with\nidentical arrangements of atoms but different\ndistributions of electrons can be written. The actual\ndistribution of electrons (the resonance hybrid) is an\naverage of the distribution indicated by the\nindividual Lewis structures (the resonance forms).\n"]], ["block_21", ["and the central atom\n"]], ["block_22", ["are shared between two atoms\n"]], ["block_23", [" (VSEPR) \ntheory used to predict the bond angles\n"]], ["block_24", ["in a molecule based on positioning regions of\nhigh electron density as far apart as possible to\nminimize electrostatic repulsion\n"]], ["block_25", [" 7 \u2022 Key Equations \n 359 \n"]]], "page_373": [["block_0", [" 360 \n 7 \u2022 Exercises \n"]], ["block_1", [" 7.5 Strengths of Ionic and Covalent Bonds \n"]], ["block_2", ["The strength of a covalent bond is measured by its\nbond dissociation energy, that is, the amount of\nenergy required to break that particular bond in a\nmole of molecules. Multiple bonds are stronger than\nsingle bonds between the same atoms. The enthalpy\nof a reaction can be estimated based on the energy\ninput required to break bonds and the energy\nreleased when new bonds are formed. For ionic\nbonds, the lattice energy is the energy required to\nseparate one mole of a compound into its gas phase\nions. Lattice energy increases for ions with higher\ncharges and shorter distances between ions. Lattice\nenergies are often calculated using the Born-Haber\ncycle, a thermochemical cycle including all of the\nenergetic steps involved in converting elements into\nan ionic compound.\n"]], ["block_3", [" 7.6 Molecular Structure and Polarity \n"]], ["block_4", ["VSEPR theory predicts the three-dimensional\n"]], ["block_5", [" Exercises \n"]], ["block_6", [" 7.1 Ionic Bonding \n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [" 1 . Does a cation gain protons to form a positive charge or does it lose electrons?\n 2 . Iron(III) sulfate [Fe2(SO4)3] is composed of Feand\nions. Explain why a sample of iron(III) sulfate is\n"]], ["block_9", [" 3 . Which of the following atoms would be expected to form negative ions in binary ionic compounds and\n"]], ["block_10", [" 4 . Which of the following atoms would be expected to form negative ions in binary ionic compounds and\n"]], ["block_11", [" 5 . Predict the charge on the monatomic ions formed from the following atoms in binary ionic compounds:\n"]], ["block_12", [" 6 . Predict the charge on the monatomic ions formed from the following atoms in binary ionic compounds:\n"]], ["block_13", ["uncharged.\n"]], ["block_14", ["which would be expected to form positive ions: P, I, Mg, Cl, In, Cs, O, Pb, Co?\n"]], ["block_15", ["which would be expected to form positive ions: Br, Ca, Na, N, F, Al, Sn, S, Cd?\n"]], ["block_16", ["(a) P\n(b) Mg\n(c) Al\n(d) O\n(e) Cl\n(f) Cs\n"]], ["block_17", ["(a) I\n(b) Sr\n(c) K\n(d) N\n(e) S\n(f) In\n"]], ["block_18", ["arrangement of atoms in a molecule. It states that\nvalence electrons will assume an electron-pair\ngeometry that minimizes repulsions between areas\nof high electron density (bonds and/or lone pairs).\nMolecular structure, which refers only to the\nplacement of atoms in a molecule and not the\nelectrons, is equivalent to electron-pair geometry\nonly when there are no lone electron pairs around\nthe central atom. A dipole moment measures a\nseparation of charge. For one bond, the bond dipole\nmoment is determined by the difference in\nelectronegativity between the two atoms. For a\nmolecule, the overall dipole moment is determined\nby both the individual bond moments and how these\ndipoles are arranged in the molecular structure.\nPolar molecules (those with an appreciable dipole\nmoment) interact with electric fields, whereas\nnonpolar molecules do not.\n"]]], "page_374": [["block_0", [" 10 . From the labels of several commercial products, prepare a list of six ionic compounds in the products. For\n"]], ["block_1", [" 7.2 Covalent Bonding \n"]], ["block_2", [" 11 . Why is it incorrect to speak of a molecule of solid NaCl?\n 12 . What information can you use to predict whether a bond between two atoms is covalent or ionic?\n 13 . Predict which of the following compounds are ionic and which are covalent, based on the location of their\n"]], ["block_3", [" 14 . Explain the difference between a nonpolar covalent bond, a polar covalent bond, and an ionic bond.\n"]], ["block_4", [" 7 . Write the electron configuration for each of the following ions:\n"]], ["block_5", [" 8 . Write the electron configuration for the monatomic ions formed from the following elements (which form\n"]], ["block_6", [" 9 . Write out the full electron configuration for each of the following atoms and for the monatomic ion found\n"]], ["block_7", ["(a) As\n"]], ["block_8", ["(b) I\n"]], ["block_9", ["(c) Be\n"]], ["block_10", ["(d) Cd\n"]], ["block_11", ["(e) O\n"]], ["block_12", ["(f) Ga\n"]], ["block_13", ["(g) Li\n"]], ["block_14", ["(h) N\n"]], ["block_15", ["(i) Sn\n"]], ["block_16", ["(j) Co\n"]], ["block_17", ["(k) Fe\n"]], ["block_18", ["(l) As\n"]], ["block_19", ["the greatest concentration of monatomic ions in seawater):\n(a) Cl\n(b) Na\n(c) Mg\n(d) Ca\n(e) K\n(f) Br\n(g) Sr\n(h) F\n"]], ["block_20", ["in binary ionic compounds containing the element:\n(a) Al\n(b) Br\n(c) Sr\n(d) Li\n(e) As\n(f) S\n"]], ["block_21", ["each compound, write the formula. (You may need to look up some formulas in a suitable reference.)\n"]], ["block_22", ["constituent atoms in the periodic table:\n(a) Cl2CO\n(b) MnO\n(c) NCl3\n(d) CoBr2\n(e) K2S\n(f) CO\n(g) CaF2\n(h) HI\n(i) CaO\n(j) IBr\n(k) CO2\n"]], ["block_23", [" 7 \u2022 Exercises \n 361 \n"]]], "page_375": [["block_0", [" 362 \n 7 \u2022 Exercises \n"]], ["block_1", [" 15 . From its position in the periodic table, determine which atom in each pair is more electronegative:\n"]], ["block_2", [" 16 . From its position in the periodic table, determine which atom in each pair is more electronegative:\n"]], ["block_3", [" 17 . From their positions in the periodic table, arrange the atoms in each of the following series in order of\n"]], ["block_4", [" 18 . From their positions in the periodic table, arrange the atoms in each of the following series in order of\n"]], ["block_5", [" 19 . Which atoms can bond to sulfur so as to produce a positive partial charge on the sulfur atom?\n 20 . Which is the most polar bond?\n"]], ["block_6", [" 21 . Identify the more polar bond in each of the following pairs of bonds:\n"]], ["block_7", [" 22 . Which of the following molecules or ions contain polar bonds?\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["(a) Br or Cl\n(b) N or O\n(c) S or O\n(d) P or S\n(e) Si or N\n(f) Ba or P\n(g) N or K\n"]], ["block_10", ["(a) N or P\n(b) N or Ge\n(c) S or F\n(d) Cl or S\n(e) H or C\n(f) Se or P\n(g) C or Si\n"]], ["block_11", ["increasing electronegativity:\n(a) C, F, H, N, O\n(b) Br, Cl, F, H, I\n(c) F, H, O, P, S\n(d) Al, H, Na, O, P\n(e) Ba, H, N, O, As\n"]], ["block_12", ["increasing electronegativity:\n(a) As, H, N, P, Sb\n(b) Cl, H, P, S, Si\n(c) Br, Cl, Ge, H, Sr\n(d) Ca, H, K, N, Si\n(e) Cl, Cs, Ge, H, Sr\n"]], ["block_13", ["(a) C\u2013C\n(b) C\u2013H\n(c) N\u2013H\n(d) O\u2013H\n(e) Se\u2013H\n"]], ["block_14", ["(a) HF or HCl\n(b) NO or CO\n(c) SH or OH\n(d) PCl or SCl\n(e) CH or NH\n(f) SO or PO\n(g) CN or NN\n"]], ["block_15", ["(a) O3\n(b) S8\n(c)\n(d)\n(e) CO2\n(f) H2S\n(g)\n"]]], "page_376": [["block_0", [" 7.3 Lewis Symbols and Structures \n"]], ["block_1", [" 23 . Write the Lewis symbols for each of the following ions:\n"]], ["block_2", [" 24 . Many monatomic ions are found in seawater, including the ions formed from the following list of elements.\n"]], ["block_3", [" 25 . Write the Lewis symbols of the ions in each of the following ionic compounds and the Lewis symbols of the\n"]], ["block_4", [" 26 . In the Lewis structures listed here, M and X represent various elements in the third period of the periodic\n"]], ["block_5", [" 27 . Write the Lewis structure for the diatomic molecule P2, an unstable form of phosphorus found in high-\n"]], ["block_6", ["(a) As\n"]], ["block_7", ["(b) I\n"]], ["block_8", ["(c) Be\n"]], ["block_9", ["(d) O\n"]], ["block_10", ["(e) Ga\n"]], ["block_11", ["(f) Li\n"]], ["block_12", ["(g) N\n"]], ["block_13", ["Write the Lewis symbols for the monatomic ions formed from the following elements:\n(a) Cl\n(b) Na\n(c) Mg\n(d) Ca\n(e) K\n(f) Br\n(g) Sr\n(h) F\n"]], ["block_14", ["atom from which they are formed:\n(a) MgS\n(b) Al2O3\n(c) GaCl3\n(d) K2O\n(e) Li3N\n(f) KF\n"]], ["block_15", ["table. Write the formula of each compound using the chemical symbols of each element:\n(a)\n"]], ["block_16", [{"image_0": "376_0.png", "coords": [91, 442, 208, 470]}]], ["block_17", ["(b)\n"]], ["block_18", [{"image_1": "376_1.png", "coords": [91, 485, 208, 514]}]], ["block_19", ["(c)\n"]], ["block_20", [{"image_2": "376_2.png", "coords": [91, 530, 208, 559]}]], ["block_21", ["(d)\n"]], ["block_22", [{"image_3": "376_3.png", "coords": [91, 575, 208, 604]}]], ["block_23", ["temperature phosphorus vapor.\n"]], ["block_24", [" 7 \u2022 Exercises \n 363 \n"]]], "page_377": [["block_0", [" 364 \n 7 \u2022 Exercises \n"]], ["block_1", [" 28 . Write Lewis structures for the following:\n"]], ["block_2", [" 29 . Write Lewis structures for the following:\n"]], ["block_3", [" 30 . Write Lewis structures for the following:\n"]], ["block_4", [" 31 . Write Lewis structures for the following:\n"]], ["block_5", [" 32 . Write Lewis structures for:\n"]], ["block_6", [" 33 . Correct the following statement: \u201cThe bonds in solid PbCl2 are ionic; the bond in a HCl molecule is\n"]], ["block_7", [" 34 . Write Lewis structures for the following molecules or ions:\n"]], ["block_8", [" 35 . Methanol, H3COH, is used as the fuel in some race cars. Ethanol, C2H5OH, is used extensively as motor fuel\n"]], ["block_9", [" 36 . Many planets in our solar system contain organic chemicals including methane (CH4) and traces of\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["(a) H2\n(b) HBr\n(c) PCl3\n(d) SF2\n(e) H2CCH2\n(f) HNNH\n(g) H2CNH\n(h) NO\n"]], ["block_12", ["(i) N2\n(j) CO\n(k) CN\n"]], ["block_13", ["(a) O2\n(b) H2CO\n(c) AsF3\n(d) ClNO\n(e) SiCl4\n(f) H3O\n"]], ["block_14", ["(g)\n(h)\n(i) HCCH\n(j) ClCN\n(k)\n"]], ["block_15", ["(a) ClF3\n(b) PCl5\n(c) BF3\n(d)\n"]], ["block_16", ["(a) SeF6\n(b) XeF4\n(c)\n(d) Cl2BBCl2 (contains a B\u2013B bond)\n"]], ["block_17", ["(a)\n(b)\n(c)\n(d) HONO\n"]], ["block_18", ["covalent. Thus, all of the valence electrons in PbCl2 are located on the Clions, and all of the valence\nelectrons in a HCl molecule are shared between the H and Cl atoms.\u201d\n"]], ["block_19", ["(a) SbH3\n(b) XeF2\n(c) Se8 (a cyclic molecule with a ring of eight Se atoms)\n"]], ["block_20", ["in Brazil. Both methanol and ethanol produce CO2 and H2O when they burn. Write the chemical equations\nfor these combustion reactions using Lewis structures instead of chemical formulas.\n"]], ["block_21", ["ethylene (C2H4), ethane (C2H6), propyne (H3CCCH), and diacetylene (HCCCCH). Write the Lewis structures\nfor each of these molecules.\n"]]], "page_378": [["block_0", [" 37 . Carbon tetrachloride was formerly used in fire extinguishers for electrical fires. It is no longer used for\n"]], ["block_1", [" 38 . Identify the atoms that correspond to each of the following electron configurations. Then, write the Lewis\n"]], ["block_2", [" 39 . The arrangement of atoms in several biologically important molecules is given here. Complete the Lewis\n"]], ["block_3", [" 40 . A compound with a molar mass of about 28 g/mol contains 85.7% carbon and 14.3% hydrogen by mass.\n"]], ["block_4", [" 41 . A compound with a molar mass of about 42 g/mol contains 85.7% carbon and 14.3% hydrogen by mass.\n"]], ["block_5", [" 42 . Two arrangements of atoms are possible for a compound with a molar mass of about 45 g/mol that\n"]], ["block_6", [" 43 . How are single, double, and triple bonds similar? How do they differ?\n"]], ["block_7", ["this purpose because of the formation of the toxic gas phosgene, Cl2CO. Write the Lewis structures for\ncarbon tetrachloride and phosgene.\n"]], ["block_8", ["symbol for the common ion formed from each atom:\n(a) 1s2s2p\n"]], ["block_9", ["(b) 1s2s2p3s\n"]], ["block_10", ["(c) 1s2s2p3s3p4s3d\n"]], ["block_11", ["(d) 1s2s2p3s3p4s3d4p\n"]], ["block_12", ["(e) 1s2s2p3s3p4s3d4p\n"]], ["block_13", ["structures of these molecules by adding multiple bonds and lone pairs. Do not add any more atoms.\n(a) the amino acid serine:\n"]], ["block_14", [{"image_0": "378_0.png", "coords": [91, 221, 202, 309]}]], ["block_15", ["(b) urea:\n"]], ["block_16", [{"image_1": "378_1.png", "coords": [91, 324, 182, 356]}]], ["block_17", ["(c) pyruvic acid:\n"]], ["block_18", [{"image_2": "378_2.png", "coords": [91, 372, 202, 424]}]], ["block_19", ["(d) uracil:\n"]], ["block_20", [{"image_3": "378_3.png", "coords": [91, 439, 172, 531]}]], ["block_21", ["(e) carbonic acid:\n"]], ["block_22", [{"image_4": "378_4.png", "coords": [91, 547, 182, 579]}]], ["block_23", ["Write the Lewis structure for a molecule of the compound.\n"]], ["block_24", ["Write the Lewis structure for a molecule of the compound.\n"]], ["block_25", ["contains 52.2% C, 13.1% H, and 34.7% O by mass. Write the Lewis structures for the two molecules.\n"]], ["block_26", [" 7 \u2022 Exercises \n 365 \n"]]], "page_379": [["block_0", [" 366 \n 7 \u2022 Exercises \n"]], ["block_1", [" 7.4 Formal Charges and Resonance \n"]], ["block_2", [" 44 . Write resonance forms that describe the distribution of electrons in each of these molecules or ions.\n"]], ["block_3", [" 45 . Write resonance forms that describe the distribution of electrons in each of these molecules or ions.\n"]], ["block_4", [" 46 . Write the resonance forms of ozone, O3, the component of the upper atmosphere that protects the Earth\n"]], ["block_5", [" 47 . Sodium nitrite, which has been used to preserve bacon and other meats, is an ionic compound. Write the\n"]], ["block_6", [" 48 . In terms of the bonds present, explain why acetic acid, CH3CO2H, contains two distinct types of carbon-\n"]], ["block_7", [" 49 . Write the Lewis structures for the following, and include resonance structures where appropriate. Indicate\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["(a) selenium dioxide, OSeO\n(b) nitrate ion,\n(c) nitric acid, HNO3 (N is bonded to an OH group and two O atoms)\n(d) benzene, C6H6:\n"]], ["block_10", [{"image_0": "379_0.png", "coords": [91, 140, 172, 234]}]], ["block_11", ["(e) the formate ion:\n"]], ["block_12", [{"image_1": "379_1.png", "coords": [91, 249, 163, 292]}]], ["block_13", ["(a) sulfur dioxide, SO2\n(b) carbonate ion,\n(c) hydrogen carbonate ion,\n(C is bonded to an OH group and two O atoms)\n"]], ["block_14", ["(d) pyridine:\n"]], ["block_15", [{"image_2": "379_2.png", "coords": [91, 359, 172, 432]}]], ["block_16", ["(e) the allyl ion:\n"]], ["block_17", [{"image_3": "379_3.png", "coords": [91, 447, 203, 491]}]], ["block_18", ["from ultraviolet radiation.\n"]], ["block_19", ["resonance forms of the nitrite ion,\n"]], ["block_20", ["oxygen bonds, whereas the acetate ion, formed by loss of a hydrogen ion from acetic acid, only contains\none type of carbon-oxygen bond. The skeleton structures of these species are shown:\n"]], ["block_21", [{"image_4": "379_4.png", "coords": [91, 582, 296, 646]}]], ["block_22", ["which has the strongest carbon-oxygen bond.\n(a) CO2\n(b) CO\n"]]], "page_380": [["block_0", [" 50 . Toothpastes containing sodium hydrogen carbonate (sodium bicarbonate) and hydrogen peroxide are\n"]], ["block_1", [" 51 . Determine the formal charge of each element in the following:\n"]], ["block_2", [" 52 . Determine the formal charge of each element in the following:\n"]], ["block_3", [" 53 . Calculate the formal charge of chlorine in the molecules Cl2, BeCl2, and ClF5.\n 54 . Calculate the formal charge of each element in the following compounds and ions:\n"]], ["block_4", [" 55 . Draw all possible resonance structures for each of these compounds. Determine the formal charge on\n"]], ["block_5", [" 56 . Based on formal charge considerations, which of the following would likely be the correct arrangement of\n"]], ["block_6", [" 57 . Based on formal charge considerations, which of the following would likely be the correct arrangement of\n"]], ["block_7", [" 58 . Based on formal charge considerations, which of the following would likely be the correct arrangement of\n"]], ["block_8", [" 59 . Draw the structure of hydroxylamine, H3NO, and assign formal charges; look up the structure. Is the actual\n"]], ["block_9", [" 60 . Iodine forms a series of fluorides (listed here). Write Lewis structures for each of the four compounds and\n"]], ["block_10", [" 61 . Write the Lewis structure and chemical formula of the compound with a molar mass of about 70 g/mol\n"]], ["block_11", [" 62 . Which of the following structures would we expect for nitrous acid? Determine the formal charges:\n"]], ["block_12", ["widely used. Write Lewis structures for the hydrogen carbonate ion and hydrogen peroxide molecule, with\nresonance forms where appropriate.\n"]], ["block_13", ["(a) HCl\n(b) CF4\n(c) PCl3\n(d) PF5\n"]], ["block_14", ["(a) H3O\n"]], ["block_15", ["(b)\n(c) NH3\n(d)\n(e) H2O2\n"]], ["block_16", ["(a) F2CO\n(b) NO\n"]], ["block_17", ["(c)\n(d)\n(e) H2CCH2\n(f) ClF3\n(g) SeF6\n(h)\n"]], ["block_18", ["each atom in each of the resonance structures:\n(a) O3\n(b) SO2\n(c)\n(d)\n"]], ["block_19", ["atoms in nitrosyl chloride: ClNO or ClON?\n"]], ["block_20", ["atoms in hypochlorous acid: HOCl or OClH?\n"]], ["block_21", ["atoms in sulfur dioxide: OSO or SOO?\n"]], ["block_22", ["structure consistent with the formal charges?\n"]], ["block_23", ["determine the formal charge of the iodine atom in each molecule:\n(a) IF\n(b) IF3\n(c) IF5\n(d) IF7\n"]], ["block_24", ["that contains 19.7% nitrogen and 80.3% fluorine by mass, and determine the formal charge of the atoms\nin this compound.\n"]], ["block_25", [{"image_0": "380_0.png", "coords": [91, 663, 242, 701]}]], ["block_26", [" 7 \u2022 Exercises \n 367 \n"]]], "page_381": [["block_0", [" 368 \n 7 \u2022 Exercises \n"]], ["block_1", [" 63 . Sulfuric acid is the industrial chemical produced in greatest quantity worldwide. About 90 billion pounds\n"]], ["block_2", [" 7.5 Strengths of Ionic and Covalent Bonds \n"]], ["block_3", [" 64 . Which bond in each of the following pairs of bonds is the strongest?\n"]], ["block_4", [" 65 . Using the bond energies in Table 7.2, determine the approximate enthalpy change for each of the\n"]], ["block_5", [" 66 . Using the bond energies in Table 7.2, determine the approximate enthalpy change for each of the\n"]], ["block_6", [" 67 . When a molecule can form two different structures, the structure with the stronger bonds is usually the\n"]], ["block_7", [" 68 . How does the bond energy of HCl(g) differ from the standard enthalpy of formation of HCl(g)?\n 69 . Using the standard enthalpy of formation data in Appendix G, show how the standard enthalpy of\n"]], ["block_8", [" 70 . Using the standard enthalpy of formation data in Appendix G, calculate the bond energy of the carbon-\n"]], ["block_9", [" 71 . Using the standard enthalpy of formation data in Appendix G, determine which bond is stronger: the S\u2013F\n"]], ["block_10", [" 72 . Using the standard enthalpy of formation data in Appendix G, determine which bond is stronger: the P\u2013Cl\n"]], ["block_11", [" 73 . Complete the following Lewis structure by adding bonds (not atoms), and then indicate the longest bond:\n"]], ["block_12", [" 74 . Use the bond energy to calculate an approximate value of \u0394H for the following reaction. Which is the more\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", ["are produced each year in the United States alone. Write the Lewis structure for sulfuric acid, H2SO4,\nwhich has two oxygen atoms and two OH groups bonded to the sulfur.\n"]], ["block_15", ["(a) C\u2013C or\n(b) C\u2013N or\n(c)\nor\n"]], ["block_16", ["(d) H\u2013F or H\u2013Cl\n(e) C\u2013H or O\u2013H\n(f) C\u2013N or C\u2013O\n"]], ["block_17", ["following reactions:\n(a)\n(b)\n(c)\n"]], ["block_18", ["following reactions:\n(a)\n(b)\n(c)\n"]], ["block_19", ["more stable form. Use bond energies to predict the correct structure of the hydroxylamine molecule:\n"]], ["block_20", [{"image_0": "381_0.png", "coords": [91, 367, 238, 419]}]], ["block_21", ["formation of HCl(g) can be used to determine the bond energy.\n"]], ["block_22", ["sulfur double bond in CS2.\n"]], ["block_23", ["bond in SF4(g) or in SF6(g)?\n"]], ["block_24", ["bond in PCl3(g) or in PCl5(g)?\n"]], ["block_25", [{"image_1": "381_1.png", "coords": [91, 548, 243, 601]}]], ["block_26", ["stable form of FNO2?\n"]], ["block_27", [{"image_2": "381_2.png", "coords": [91, 629, 277, 673]}]]], "page_382": [["block_0", [" 75 . Use principles of atomic structure to answer each of the following:\n"]], ["block_1", [" 76 . The lattice energy of LiF is 1023 kJ/mol, and the Li\u2013F distance is 200.8 pm. NaF crystallizes in the same\n"]], ["block_2", [" 77 . For which of the following substances is the least energy required to convert one mole of the solid into\n"]], ["block_3", [" 78 . The reaction of a metal, M, with a halogen, X2, proceeds by an exothermic reaction as indicated by this\n"]], ["block_4", [" 79 . The lattice energy of LiF is 1023 kJ/mol, and the Li\u2013F distance is 201 pm. MgO crystallizes in the same\n"]], ["block_5", [" 80 . Which compound in each of the following pairs has the larger lattice energy? Note: Mgand Lihave\n"]], ["block_6", [" 81 . Which compound in each of the following pairs has the larger lattice energy? Note: Baand\n"]], ["block_7", ["1 This question is taken from the Chemistry Advanced Placement Examination and is used with the permission of the Educational\nTesting Service.\n"]], ["block_8", ["(a) The radius of the Ca atom is 197 pm; the radius of the Caion is 99 pm. Account for the difference.\n(b) The lattice energy of CaO(s) is \u20133460 kJ/mol; the lattice energy of K2O is \u20132240 kJ/mol. Account for the\ndifference.\n(c) Given these ionization values, explain the difference between Ca and K with regard to their first and second\nionization energies.\n"]], ["block_9", ["(d) The first ionization energy of Mg is 738 kJ/mol and that of Al is 578 kJ/mol. Account for this difference.\n"]], ["block_10", ["structure as LiF but with a Na\u2013F distance of 231 pm. Which of the following values most closely\napproximates the lattice energy of NaF: 510, 890, 1023, 1175, or 4090 kJ/mol? Explain your choice.\n"]], ["block_11", ["separate ions?\n(a) MgO\n(b) SrO\n(c) KF\n(d) CsF\n(e) MgF2\n"]], ["block_12", ["equation:\nFor each of the following, indicate which option will make the\n"]], ["block_13", ["reaction more exothermic. Explain your answers.\n(a) a large radius vs. a small radius for M\n"]], ["block_14", ["(b) a high ionization energy vs. a low ionization energy for M\n(c) an increasing bond energy for the halogen\n(d) a decreasing electron affinity for the halogen\n(e) an increasing size of the anion formed by the halogen\n"]], ["block_15", ["structure as LiF but with a Mg\u2013O distance of 205 pm. Which of the following values most closely\napproximates the lattice energy of MgO: 256 kJ/mol, 512 kJ/mol, 1023 kJ/mol, 2046 kJ/mol, or 4008 kJ/\nmol? Explain your choice.\n"]], ["block_16", ["similar radii; Oand Fhave similar radii. Explain your choices.\n(a) MgO or MgSe\n(b) LiF or MgO\n(c) Li2O or LiCl\n(d) Li2Se or MgO\n"]], ["block_17", ["Khave similar radii; Sand Clhave similar radii. Explain your choices.\n(a) K2O or Na2O\n(b) K2S or BaS\n(c) KCl or BaS\n(d) BaS or BaCl2\n"]], ["block_18", [" Element \n First Ionization Energy (kJ/ mol) \n Second Ionization Energy (kJ/ \n mol) \n"]], ["block_19", ["Ca\n590\n1140\n"]], ["block_20", ["K\n419\n3050\n"]], ["block_21", [" 7 \u2022 Exercises \n 369 \n"]]], "page_383": [["block_0", [" 370 \n 7 \u2022 Exercises \n"]], ["block_1", [" 82 . Which of the following compounds requires the most energy to convert one mole of the solid into separate\n"]], ["block_2", [" 83 . Which of the following compounds requires the most energy to convert one mole of the solid into separate\n"]], ["block_3", [" 84 . The lattice energy of KF is 794 kJ/mol, and the interionic distance is 269 pm. The Na\u2013F\n"]], ["block_4", [" 7.6 Molecular Structure and Polarity \n"]], ["block_5", [" 85 . Explain why the HOH molecule is bent, whereas the HBeH molecule is linear.\n 86 . What feature of a Lewis structure can be used to tell if a molecule\u2019s (or ion\u2019s) electron-pair geometry and\n"]], ["block_6", [" 87 . Explain the difference between electron-pair geometry and molecular structure.\n 88 . Why is the H\u2013N\u2013H angle in NH3 smaller than the H\u2013C\u2013H bond angle in CH4? Why is the H\u2013N\u2013H angle in\n"]], ["block_7", [" 89 . Explain how a molecule that contains polar bonds can be nonpolar.\n 90 . As a general rule, MXn molecules (where M represents a central atom and X represents terminal atoms; n\n"]], ["block_8", [" 91 . Predict the electron pair geometry and the molecular structure of each of the following molecules or ions:\n"]], ["block_9", [" 92 . Identify the electron pair geometry and the molecular structure of each of the following molecules or ions:\n"]], ["block_10", [" 93 . What are the electron-pair geometry and the molecular structure of each of the following molecules or\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["ions?\n(a) MgO\n(b) SrO\n(c) KF\n(d) CsF\n(e) MgF2\n"]], ["block_13", ["ions?\n(a) K2S\n(b) K2O\n(c) CaS\n(d) Cs2S\n(e) CaO\n"]], ["block_14", ["distance in NaF, which has the same structure as KF, is 231 pm. Which of the following values is the\nclosest approximation of the lattice energy of NaF: 682 kJ/mol, 794 kJ/mol, 924 kJ/mol, 1588 kJ/mol, or\n3175 kJ/mol? Explain your answer.\n"]], ["block_15", ["molecular structure will be identical?\n"]], ["block_16", ["= 2 \u2013 5) are polar if there is one or more lone pairs of electrons on M. NH3 (M = N, X = H, n = 3) is an\nexample. There are two molecular structures with lone pairs that are exceptions to this rule. What are\nthey?\n"]], ["block_17", ["(a) SF6\n(b) PCl5\n(c) BeH2\n(d)\n"]], ["block_18", ["(a)\n(b) CF4\n(c) BF3\n(d)\n(e) BeCl2\n"]], ["block_19", ["ions?\n(a) ClF5\n(b)\n(c)\n(d) PCl3\n(e) SeF4\n(f)\n"]], ["block_20", ["identical to the H\u2013C\u2013H bond angle in CH4?\n"]]], "page_384": [["block_0", [" 94 . Predict the electron pair geometry and the molecular structure of each of the following ions:\n"]], ["block_1", [" 95 . Identify the electron pair geometry and the molecular structure of each of the following molecules:\n"]], ["block_2", [" 96 . Predict the electron pair geometry and the molecular structure of each of the following:\n"]], ["block_3", [" 97 . Which of the following molecules and ions contain polar bonds? Which of these molecules and ions have\n"]], ["block_4", [" 98 . Which of these molecules and ions contain polar bonds? Which of these molecules and ions have dipole\n"]], ["block_5", [" 99 . Which of the following molecules have dipole moments?\n"]], ["block_6", ["(a) H3O\n"]], ["block_7", ["(b)\n(c)\n(d)\n(e) ICl3\n(f) XeF4\n(g) SF2\n"]], ["block_8", ["(a) ClNO (N is the central atom)\n(b) CS2\n(c) Cl2CO (C is the central atom)\n(d) Cl2SO (S is the central atom)\n(e) SO2F2 (S is the central atom)\n(f) XeO2F2 (Xe is the central atom)\n(g)\n(Cl is the central atom)\n"]], ["block_9", ["(a) IOF5 (I is the central atom)\n(b) POCl3 (P is the central atom)\n(c) Cl2SeO (Se is the central atom)\n(d) ClSO(S is the central atom)\n(e) F2SO (S is the central atom)\n(f)\n(g)\n"]], ["block_10", ["dipole moments?\n(a) ClF5\n(b)\n(c)\n(d) PCl3\n(e) SeF4\n(f)\n(g) XeF2\n"]], ["block_11", ["moments?\n(a) H3O\n"]], ["block_12", ["(b)\n(c)\n(d)\n(e) ICl3\n(f) XeF4\n(g) SF2\n"]], ["block_13", ["(a) CS2\n(b) SeS2\n(c) CCl2F2\n(d) PCl3 (P is the central atom)\n(e) ClNO (N is the central atom)\n"]], ["block_14", [" 7 \u2022 Exercises \n 371 \n"]]], "page_385": [["block_0", [" 372 \n 7 \u2022 Exercises \n"]], ["block_1", [" 100 . Identify the molecules with a dipole moment:\n"]], ["block_2", [" 101 . The molecule XF3 has a dipole moment. Is X boron or phosphorus?\n 102 . The molecule XCl2 has a dipole moment. Is X beryllium or sulfur?\n 103 . Is the Cl2BBCl2 molecule polar or nonpolar?\n 104 . There are three possible structures for PCl2F3 with phosphorus as the central atom. Draw them and\n"]], ["block_3", [" 105 . Describe the molecular structure around the indicated atom or atoms:\n"]], ["block_4", [" 106 . Draw the Lewis structures and predict the shape of each compound or ion:\n"]], ["block_5", [" 107 . A molecule with the formula AB2, in which A and B represent different atoms, could have one of three\n"]], ["block_6", [" 108 . A molecule with the formula AB3, in which A and B represent different atoms, could have one of three\n"]], ["block_7", [" 109 . Draw the Lewis electron dot structures for these molecules, including resonance structures where\n"]], ["block_8", [" 110 . What is the molecular structure of the stable form of FNO2? (N is the central atom.)\n 111 . A compound with a molar mass of about 42 g/mol contains 85.7% carbon and 14.3% hydrogen. What is\n"]], ["block_9", [" 112 . Use the simulation (http://openstax.org/l/16MolecPolarity) to perform the following exercises for a two-\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["(a) SF4\n(b) CF4\n(c) Cl2CCBr2\n(d) CH3Cl\n(e) H2CO\n"]], ["block_12", ["discuss how measurements of dipole moments could help distinguish among them.\n"]], ["block_13", ["(a) the sulfur atom in sulfuric acid, H2SO4 [(HO)2SO2]\n(b) the chlorine atom in chloric acid, HClO3 [HOClO2]\n(c) the oxygen atom in hydrogen peroxide, HOOH\n(d) the nitrogen atom in nitric acid, HNO3 [HONO2]\n(e) the oxygen atom in the OH group in nitric acid, HNO3 [HONO2]\n(f) the central oxygen atom in the ozone molecule, O3\n(g) each of the carbon atoms in propyne, CH3CCH\n(h) the carbon atom in Freon, CCl2F2\n(i) each of the carbon atoms in allene, H2CCCH2\n"]], ["block_14", ["(a) CO2\n(b)\n(c) SO3\n(d)\n"]], ["block_15", ["different shapes. Sketch and name the three different shapes that this molecule might have. Give an\nexample of a molecule or ion for each shape.\n"]], ["block_16", ["different shapes. Sketch and name the three different shapes that this molecule might have. Give an\nexample of a molecule or ion that has each shape.\n"]], ["block_17", ["appropriate:\n(a)\n(b) CS2\n(c) CS\n(d) predict the molecular shapes for\nand CS2 and explain how you arrived at your predictions\n"]], ["block_18", ["its molecular structure?\n"]], ["block_19", ["atom molecule:\n(a) Adjust the electronegativity value so the bond dipole is pointing toward B. Then determine what the\nelectronegativity values must be to switch the dipole so that it points toward A.\n(b) With a partial positive charge on A, turn on the electric field and describe what happens.\n(c) With a small partial negative charge on A, turn on the electric field and describe what happens.\n(d) Reset all, and then with a large partial negative charge on A, turn on the electric field and describe\nwhat happens.\n"]]], "page_386": [["block_0", [" 113 . Use the simulation (http://openstax.org/l/16MolecPolarity) to perform the following exercises for a real\n"]], ["block_1", [" 114 . Use the Molecule Shape simulator (http://openstax.org/l/16MolecShape) to build a molecule. Starting\n"]], ["block_2", [" 115 . Use the Molecule Shape simulator (http://openstax.org/l/16MolecShape) to explore real molecules. On\n"]], ["block_3", [" 116 . Use the Molecule Shape simulator (http://openstax.org/l/16MolecShape) to explore real molecules. On\n"]], ["block_4", ["molecule. You may need to rotate the molecules in three dimensions to see certain dipoles.\n(a) Sketch the bond dipoles and molecular dipole (if any) for O3. Explain your observations.\n(b) Look at the bond dipoles for NH3. Use these dipoles to predict whether N or H is more electronegative.\n(c) Predict whether there should be a molecular dipole for NH3 and, if so, in which direction it will point.\nCheck the molecular dipole box to test your hypothesis.\n"]], ["block_5", ["with the central atom, click on the double bond to add one double bond. Then add one single bond and\none lone pair. Rotate the molecule to observe the complete geometry. Name the electron group geometry\nand molecular structure and predict the bond angle. Then click the check boxes at the bottom and right\nof the simulator to check your answers.\n"]], ["block_6", ["the Real Molecules tab, select H2O. Switch between the \u201creal\u201d and \u201cmodel\u201d modes. Explain the difference\nobserved.\n"]], ["block_7", ["the Real Molecules tab, select \u201cmodel\u201d mode and S2O. What is the model bond angle? Explain whether\nthe \u201creal\u201d bond angle should be larger or smaller than the ideal model angle.\n"]], ["block_8", [" 7 \u2022 Exercises \n 373 \n"]]], "page_387": [["block_0", [" 374 \n 7 \u2022 Exercises \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_388": [["block_0", ["CHAPTER 8\nAdvanced Theories of Covalent\nBonding\n"]], ["block_1", [{"image_0": "388_0.png", "coords": [72, 131, 622, 385]}]], ["block_2", [" Figure 8.1 \nOxygen molecules orient randomly most of the time, as shown in the top magnified view. However,\n"]], ["block_3", ["when we pour liquid oxygen through a magnet, the molecules line up with the magnetic field, and the attraction\nallows them to stay suspended between the poles of the magnet where the magnetic field is strongest. Other\ndiatomic molecules (like N2) flow past the magnet. The detailed explanation of bonding described in this chapter\nallows us to understand this phenomenon. (credit: modification of work by Jefferson Lab)\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 8.1 Valence Bond Theory \n 8.2 Hybrid Atomic Orbitals \n 8.3 Multiple Bonds \n 8.4 Molecular Orbital Theory \n"]], ["block_6", [" INTRODUCTION \n"]], ["block_7", ["molecules with stable Lewis structures and that we can predict the shapes of those molecules by valence shell\nelectron pair repulsion (VSEPR) theory. These ideas provide an important starting point for understanding\nchemical bonding. But these models sometimes fall short in their abilities to predict the behavior of real\nsubstances. How can we reconcile the geometries of s, p, and d atomic orbitals with molecular shapes that\nshow angles like 120\u00b0 and 109.5\u00b0? Furthermore, we know that electrons and magnetic behavior are related\nthrough electromagnetic fields. Both N2 and O2 have fairly similar Lewis structures that contain lone pairs of\nelectrons.\n"]], ["block_8", [{"image_1": "388_1.png", "coords": [72, 688, 189, 707]}]], ["block_9", ["Yet oxygen demonstrates very different magnetic behavior than nitrogen. We can pour liquid nitrogen through\n"]], ["block_10", ["We have examined the basic ideas of bonding, showing that atoms share electrons to form\n"]]], "page_389": [["block_0", [" 376 \n 8 \u2022 Advanced Theories of Covalent Bonding \n"]], ["block_1", ["There are successful theories that describe the electronic structure of atoms. We can use quantum mechanics\nto predict the specific regions around an atom where electrons are likely to be located: A spherical shape for an\ns orbital, a dumbbell shape for a p orbital, and so forth. However, these predictions only describe the orbitals\naround free atoms. When atoms bond to form molecules, atomic orbitals are not sufficient to describe the\nregions where electrons will be located in the molecule. A more complete understanding of electron\ndistributions requires a model that can account for the electronic structure of molecules. One popular theory\nholds that a covalent bond forms when a pair of electrons is shared by two atoms and is simultaneously\nattracted by the nuclei of both atoms. In the following sections, we will discuss how such bonds are described\nby valence bond theory and hybridization.\n"]], ["block_2", ["a magnetic field with no visible interactions, while liquid oxygen (shown in Figure 8.1) is attracted to the\nmagnet and floats in the magnetic field. We need to understand the additional concepts of valence bond theory,\norbital hybridization, and molecular orbital theory to understand these observations.\n"]], ["block_3", [" 8.1 Valence Bond Theory \n"]], ["block_4", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_5", ["As we know, a scientific theory is a strongly supported explanation for observed natural laws or large bodies of\nexperimental data. For a theory to be accepted, it must explain experimental data and be able to predict\nbehavior. For example, VSEPR theory has gained widespread acceptance because it predicts three-\ndimensional molecular shapes that are consistent with experimental data collected for thousands of different\nmolecules. However, VSEPR theory does not provide an explanation of chemical bonding.\n"]], ["block_6", [" Valence bond theory describes a covalent bond as the overlap of half-filled atomic orbitals (each containing a\nsingle electron) that yield a pair of electrons shared between the two bonded atoms. We say that orbitals on two\ndifferent atoms overlap when a portion of one orbital and a portion of a second orbital occupy the same region\nof space. According to valence bond theory, a covalent bond results when two conditions are met: (1) an orbital\non one atom overlaps an orbital on a second atom and (2) the single electrons in each orbital combine to form\nan electron pair. The mutual attraction between this negatively charged electron pair and the two atoms\u2019\npositively charged nuclei serves to physically link the two atoms through a force we define as a covalent bond.\nThe strength of a covalent bond depends on the extent of overlap of the orbitals involved. Orbitals that overlap\nextensively form bonds that are stronger than those that have less overlap.\n"]], ["block_7", ["The energy of the system depends on how much the orbitals overlap. Figure 8.2 illustrates how the sum of the\nenergies of two hydrogen atoms (the colored curve) changes as they approach each other. When the atoms are\nfar apart there is no overlap, and by convention we set the sum of the energies at zero. As the atoms move\ntogether, their orbitals begin to overlap. Each electron begins to feel the attraction of the nucleus in the other\natom. In addition, the electrons begin to repel each other, as do the nuclei. While the atoms are still widely\nseparated, the attractions are slightly stronger than the repulsions, and the energy of the system decreases. (A\nbond begins to form.) As the atoms move closer together, the overlap increases, so the attraction of the nuclei\nfor the electrons continues to increase (as do the repulsions among electrons and between the nuclei). At some\nspecific distance between the atoms, which varies depending on the atoms involved, the energy reaches its\nlowest (most stable) value. This optimum distance between the two bonded nuclei is the bond distance\nbetween the two atoms. The bond is stable because at this point, the attractive and repulsive forces combine to\ncreate the lowest possible energy configuration. If the distance between the nuclei were to decrease further,\nthe repulsions between nuclei and the repulsions as electrons are confined in closer proximity to each other\nwould become stronger than the attractive forces. The energy of the system would then rise (making the\nsystem destabilized), as shown at the far left of Figure 8.2.\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["\u2022\nDescribe the formation of covalent bonds in terms of atomic orbital overlap\n"]], ["block_10", ["\u2022\nDefine and give examples of \u03c3 and \u03c0 bonds\n"]]], "page_390": [["block_0", [" FIGURE 8.2 \n(a) The interaction of two hydrogen atoms changes as a function of distance. (b) The energy of the\n"]], ["block_1", ["system changes as the atoms interact. The lowest (most stable) energy occurs at a distance of 74 pm, which is the\nbond length observed for the H2 molecule.\n"]], ["block_2", ["The bond energy is the difference between the energy minimum (which occurs at the bond distance) and the\nenergy of the two separated atoms. This is the quantity of energy released when the bond is formed.\nConversely, the same amount of energy is required to break the bond. For the H2 molecule shown in Figure 8.2,\nat the bond distance of 74 pm the system is 7.24\n10J lower in energy than the two separated hydrogen\n"]], ["block_3", ["atoms. This may seem like a small number. However, we know from our earlier description of\nthermochemistry that bond energies are often discussed on a per-mole basis. For example, it requires 7.24\n10J to break one H\u2013H bond, but it takes 4.36\n10J to break 1 mole of H\u2013H bonds. A comparison of some\n"]], ["block_4", ["bond lengths and energies is shown in Table 8.1. We can find many of these bonds in a variety of molecules,\nand this table provides average values. For example, breaking the first C\u2013H bond in CH4 requires 439.3 kJ/mol,\nwhile breaking the first C\u2013H bond in H\u2013CH2C6H5 (a common paint thinner) requires 375.5 kJ/mol.\n"]], ["block_5", [" TABLE 8.1 \n"]], ["block_6", [" Bond \n Length (pm) \n Energy (kJ/mol) \n Bond \n Length (pm) \n Energy (kJ/mol) \n"]], ["block_7", ["H\u2013H\n74\n436\nC\u2013O\n140.1\n358\n"]], ["block_8", ["H\u2013C\n106.8\n413\n119.7\n745\n"]], ["block_9", ["H\u2013N\n101.5\n391\n113.7\n1072\n"]], ["block_10", ["H\u2013O\n97.5\n467\nH\u2013Cl\n127.5\n431\n"]], ["block_11", [{"image_0": "390_0.png", "coords": [130, 57, 481, 355]}]], ["block_12", ["Representative Bond Energies and Lengths\n"]], ["block_13", [" 8.1 \u2022 Valence Bond Theory \n 377 \n"]]], "page_391": [["block_0", [" 378 \n 8 \u2022 Advanced Theories of Covalent Bonding \n"]], ["block_1", ["In addition to the distance between two orbitals, the orientation of orbitals also affects their overlap (other than\nfor two s orbitals, which are spherically symmetric). Greater overlap is possible when orbitals are oriented\nsuch that they overlap on a direct line between the two nuclei. Figure 8.3 illustrates this for two p orbitals from\ndifferent atoms; the overlap is greater when the orbitals overlap end to end rather than at an angle.\n"]], ["block_2", [" FIGURE 8.3 \n(a) The overlap of two p orbitals is greatest when the orbitals are directed end to end. (b) Any other\n"]], ["block_3", ["arrangement results in less overlap. The dots indicate the locations of the nuclei.\n"]], ["block_4", ["The overlap of two s orbitals (as in H2), the overlap of an s orbital and a p orbital (as in HCl), and the end-to-end\noverlap of two p orbitals (as in Cl2) all produce sigma bonds ( \u03c3 bonds) , as illustrated in Figure 8.4. A \u03c3 bond is\na covalent bond in which the electron density is concentrated in the region along the internuclear axis; that is,\na line between the nuclei would pass through the center of the overlap region. Single bonds in Lewis structures\nare described as \u03c3 bonds in valence bond theory.\n"]], ["block_5", [" FIGURE 8.4 \nSigma (\u03c3) bonds form from the overlap of the following: (a) two s orbitals, (b) an s orbital and a p\n"]], ["block_6", ["orbital, and (c) two p orbitals. The dots indicate the locations of the nuclei.\n"]], ["block_7", ["A pi bond (\u03c0 bond) is a type of covalent bond that results from the side-by-side overlap of two p orbitals, as\nillustrated in Figure 8.5. In a \u03c0 bond, the regions of orbital overlap lie on opposite sides of the internuclear axis.\nAlong the axis itself, there is a node , that is, a plane with no probability of finding an electron.\n"]], ["block_8", [" FIGURE 8.5 \nPi (\u03c0) bonds form from the side-by-side overlap of two p orbitals. The dots indicate the location of the\n"]], ["block_9", ["nuclei.\n"]], ["block_10", ["While all single bonds are \u03c3 bonds, multiple bonds consist of both \u03c3 and \u03c0 bonds. As the Lewis structures\nbelow suggest, O2 contains a double bond, and N2 contains a triple bond. The double bond consists of one \u03c3\nbond and one \u03c0 bond, and the triple bond consists of one \u03c3 bond and two \u03c0 bonds. Between any two atoms, the\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", [" TABLE 8.1 \n"]], ["block_13", [" Bond \n Length (pm) \n Energy (kJ/mol) \n Bond \n Length (pm) \n Energy (kJ/mol) \n"]], ["block_14", ["C\u2013C\n150.6\n347\nH\u2013Br\n141.4\n366\n"]], ["block_15", ["C\u2013N\n142.1\n305\n120.8\n498\n"]], ["block_16", ["133.5\n614\nH\u2013I\n160.9\n298\n"]], ["block_17", ["120.8\n839\nO\u2013O\n148\n146\n"]], ["block_18", ["130.0\n615\nF\u2013F\n141.2\n159\n"]], ["block_19", ["116.1\n891\nCl\u2013Cl\n198.8\n243\n"]], ["block_20", [{"image_0": "391_0.png", "coords": [189, 326, 423, 383]}]], ["block_21", [{"image_1": "391_1.png", "coords": [189, 487, 423, 534]}]], ["block_22", [{"image_2": "391_2.png", "coords": [247, 613, 364, 654]}]]], "page_392": [["block_0", ["first bond formed will always be a \u03c3 bond, but there can only be one \u03c3 bond in any one location. In any multiple\nbond, there will be one \u03c3 bond, and the remaining one or two bonds will be \u03c0 bonds. These bonds are\ndescribed in more detail later in this chapter.\n"]], ["block_1", [{"image_0": "392_0.png", "coords": [72, 101, 306, 153]}]], ["block_2", ["As seen in Table 8.1, an average carbon-carbon single bond is 347 kJ/mol, while in a carbon-carbon double\nbond, the \u03c0 bond increases the bond strength by 267 kJ/mol. Adding an additional \u03c0 bond causes a further\nincrease of 225 kJ/mol. We can see a similar pattern when we compare other \u03c3 and \u03c0 bonds. Thus, each\nindividual \u03c0 bond is generally weaker than a corresponding \u03c3 bond between the same two atoms. In a \u03c3 bond,\nthere is a greater degree of orbital overlap than in a \u03c0 bond.\n"]], ["block_3", [" Counting \u03c3 and \u03c0 Bonds \n"]], ["block_4", [{"image_1": "392_1.png", "coords": [72, 278, 189, 340]}]], ["block_5", ["Butadiene, C4H6, is used to make synthetic rubber. Identify the number of \u03c3 and \u03c0 bonds contained in this\nmolecule.\n"]], ["block_6", [" Solution \n"]], ["block_7", ["There are six \u03c3 C\u2013H bonds and one \u03c3 C\u2013C bond, for a total of seven from the single bonds. There are two\ndouble bonds that each have a \u03c0 bond in addition to the \u03c3 bond. This gives a total nine \u03c3 and two \u03c0 bonds\noverall.\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["Identify each illustration as depicting a \u03c3 or \u03c0 bond:\n"]], ["block_10", ["(a) side-by-side overlap of a 4p and a 2p orbital\n"]], ["block_11", ["(b) end-to-end overlap of a 4p and 4p orbital\n"]], ["block_12", ["(c) end-to-end overlap of a 4p and a 2p orbital\n"]], ["block_13", [{"image_2": "392_2.png", "coords": [72, 525, 423, 580]}]], ["block_14", [" Answer: \n(a) is a \u03c0 bond with a node along the axis connecting the nuclei while (b) and (c) are \u03c3 bonds that overlap along\nthe axis.\n"]], ["block_15", [" 8.2 Hybrid Atomic Orbitals \n"]], ["block_16", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_17", ["\u2022\nExplain the concept of atomic orbital hybridization\n"]], ["block_18", ["\u2022\nDetermine the hybrid orbitals associated with various molecular geometries\n"]], ["block_19", ["EXAMPLE 8.1\n"]], ["block_20", [" 8.2 \u2022 Hybrid Atomic Orbitals \n 379 \n"]]], "page_393": [["block_0", [" 380 \n 8 \u2022 Advanced Theories of Covalent Bonding \n"]], ["block_1", ["Thinking in terms of overlapping atomic orbitals is one way for us to explain how chemical bonds form in\ndiatomic molecules. However, to understand how molecules with more than two atoms form stable bonds, we\nrequire a more detailed model. As an example, let us consider the water molecule, in which we have one\noxygen atom bonding to two hydrogen atoms. Oxygen has the electron configuration 1s2s2p, with two\nunpaired electrons (one in each of the two 2p orbitals). Valence bond theory would predict that the two O\u2013H\nbonds form from the overlap of these two 2p orbitals with the 1s orbitals of the hydrogen atoms. If this were the\ncase, the bond angle would be 90\u00b0, as shown in Figure 8.6, because p orbitals are perpendicular to each other.\nExperimental evidence shows that the bond angle is 104.5\u00b0, not 90\u00b0. The prediction of the valence bond theory\nmodel does not match the real-world observations of a water molecule; a different model is needed.\n"]], ["block_2", [" FIGURE 8.6 \nThe hypothetical overlap of two of the 2p orbitals on an oxygen atom (red) with the 1s orbitals of two\n"]], ["block_3", ["hydrogen atoms (blue) would produce a bond angle of 90\u00b0. This is not consistent with experimental evidence.\n"]], ["block_4", ["Quantum-mechanical calculations suggest why the observed bond angles in H2O differ from those predicted\nby the overlap of the 1s orbital of the hydrogen atoms with the 2p orbitals of the oxygen atom. The\nmathematical expression known as the wave function, \u03c8, contains information about each orbital and the\nwavelike properties of electrons in an isolated atom. When atoms are bound together in a molecule, the wave\nfunctions combine to produce new mathematical descriptions that have different shapes. This process of\ncombining the wave functions for atomic orbitals is called hybridization and is mathematically accomplished\nby the linear combination of atomic orbitals, LCAO, (a technique that we will encounter again later). The new\norbitals that result are called hybrid orbitals . The valence orbitals in an isolated oxygen atom are a 2s orbital\nand three 2p orbitals. The valence orbitals in an oxygen atom in a water molecule differ; they consist of four\nequivalent hybrid orbitals that point approximately toward the corners of a tetrahedron (Figure 8.7).\nConsequently, the overlap of the O and H orbitals should result in a tetrahedral bond angle (109.5\u00b0). The\nobserved angle of 104.5\u00b0 is experimental evidence for which quantum-mechanical calculations give a useful\nexplanation: Valence bond theory must include a hybridization component to give accurate predictions.\n"]], ["block_5", [" FIGURE 8.7 \n(a) A water molecule has four regions of electron density, so VSEPR theory predicts a tetrahedral\n"]], ["block_6", ["arrangement of hybrid orbitals. (b) Two of the hybrid orbitals on oxygen contain lone pairs, and the other two overlap\nwith the 1s orbitals of hydrogen atoms to form the O\u2013H bonds in H2O. This description is more consistent with the\nexperimental structure.\n"]], ["block_7", ["The following ideas are important in understanding hybridization:\n"]], ["block_8", ["1 Note that orbitals may sometimes be drawn in an elongated \u201cballoon\u201d shape rather than in a more realistic \u201cplump\u201d shape in\norder to make the geometry easier to visualize.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["1.\nHybrid orbitals do not exist in isolated atoms. They are formed only in covalently bonded atoms.\n"]], ["block_11", ["2.\nHybrid orbitals have shapes and orientations that are very different from those of the atomic orbitals in\nisolated atoms.\n"]], ["block_12", ["3.\nA set of hybrid orbitals is generated by combining atomic orbitals. The number of hybrid orbitals in a set is\nequal to the number of atomic orbitals that were combined to produce the set.\n"]], ["block_13", [{"image_0": "393_0.png", "coords": [189, 459, 423, 562]}]], ["block_14", [{"image_1": "393_1.png", "coords": [247, 177, 364, 255]}]]], "page_394": [["block_0", [" sp Hybridization \n"]], ["block_1", ["In the following sections, we shall discuss the common types of hybrid orbitals.\n"]], ["block_2", ["The beryllium atom in a gaseous BeCl2 molecule is an example of a central atom with no lone pairs of electrons\nin a linear arrangement of three atoms. There are two regions of valence electron density in the BeCl2 molecule\nthat correspond to the two covalent Be\u2013Cl bonds. To accommodate these two electron domains, two of the Be\natom\u2019s four valence orbitals will mix to yield two hybrid orbitals. This hybridization process involves mixing of\nthe valence s orbital with one of the valence p orbitals to yield two equivalent sp hybrid orbitals that are\noriented in a linear geometry (Figure 8.8). In this figure, the set of sp orbitals appears similar in shape to the\noriginal p orbital, but there is an important difference. The number of atomic orbitals combined always equals\nthe number of hybrid orbitals formed. The p orbital is one orbital that can hold up to two electrons. The sp set\nis two equivalent orbitals that point 180\u00b0 from each other. The two electrons that were originally in the s orbital\nare now distributed to the two sp orbitals, which are half filled. In gaseous BeCl2, these half-filled hybrid\norbitals will overlap with orbitals from the chlorine atoms to form two identical \u03c3 bonds.\n"]], ["block_3", [{"image_0": "394_0.png", "coords": [72, 297, 540, 519]}]], ["block_4", [" FIGURE 8.8 \nHybridization of an s orbital (blue) and a p orbital (red) of the same atom produces two sp hybrid\n"]], ["block_5", ["orbitals (yellow). Each hybrid orbital is oriented primarily in just one direction. Note that each sp orbital contains one\nlobe that is significantly larger than the other. The set of two sp orbitals are oriented at 180\u00b0, which is consistent\nwith the geometry for two domains.\n"]], ["block_6", ["We illustrate the electronic differences in an isolated Be atom and in the bonded Be atom in the orbital energy-\nlevel diagram in Figure 8.9. These diagrams represent each orbital by a horizontal line (indicating its energy)\nand each electron by an arrow. Energy increases toward the top of the diagram. We use one upward arrow to\nindicate one electron in an orbital and two arrows (up and down) to indicate two electrons of opposite spin.\n"]], ["block_7", ["4.\nAll orbitals in a set of hybrid orbitals are equivalent in shape and energy.\n"]], ["block_8", ["5.\nThe type of hybrid orbitals formed in a bonded atom depends on its electron-pair geometry as predicted\nby the VSEPR theory.\n"]], ["block_9", ["6.\nHybrid orbitals overlap to form \u03c3 bonds. Unhybridized orbitals overlap to form \u03c0 bonds.\n"]], ["block_10", [" 8.2 \u2022 Hybrid Atomic Orbitals \n 381 \n"]]], "page_395": [["block_0", [" 382 \n 8 \u2022 Advanced Theories of Covalent Bonding \n"]], ["block_1", [" sp 2 Hybridization \n"]], ["block_2", ["The valence orbitals of a central atom surrounded by three regions of electron density consist of a set of three\n sp 2 hybrid orbitals and one unhybridized p orbital. This arrangement results from sphybridization, the\nmixing of one s orbital and two p orbitals to produce three identical hybrid orbitals oriented in a trigonal\nplanar geometry (Figure 8.10).\n"]], ["block_3", [{"image_0": "395_0.png", "coords": [72, 57, 540, 202]}]], ["block_4", [" FIGURE 8.9 \nThis orbital energy-level diagram shows the sp hybridized orbitals on Be in the linear BeCl2 molecule.\n"]], ["block_5", ["Each of the two sp hybrid orbitals holds one electron and is thus half filled and available for bonding via overlap with\na Cl 3p orbital.\n"]], ["block_6", ["When atomic orbitals hybridize, the valence electrons occupy the newly created orbitals. The Be atom had two\nvalence electrons, so each of the sp orbitals gets one of these electrons. Each of these electrons pairs up with\nthe unpaired electron on a chlorine atom when a hybrid orbital and a chlorine orbital overlap during the\nformation of the Be\u2013Cl bonds.\n"]], ["block_7", ["Any central atom surrounded by just two regions of valence electron density in a molecule will exhibit sp\nhybridization. Other examples include the mercury atom in the linear HgCl2 molecule, the zinc atom in\nZn(CH3)2, which contains a linear C\u2013Zn\u2013C arrangement, and the carbon atoms in HCCH and CO2.\n"]], ["block_8", ["Check out the University of Wisconsin-Oshkosh website (http://openstax.org/l/16hybridorbital) to learn about\nvisualizing hybrid orbitals in three dimensions.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["LINK TO LEARNING\n"]]], "page_396": [["block_0", [{"image_0": "396_0.png", "coords": [72, 57, 540, 361]}]], ["block_1", [" FIGURE 8.10 \nThe hybridization of an s orbital (blue) and two p orbitals (red) produces three equivalent sp\n"]], ["block_2", ["hybridized orbitals (yellow) oriented at 120\u00b0 with respect to each other. The remaining unhybridized p orbital is not\nshown here, but is located along the z axis.\n"]], ["block_3", ["Although quantum mechanics yields the \u201cplump\u201d orbital lobes as depicted in Figure 8.10, sometimes for\nclarity these orbitals are drawn thinner and without the minor lobes, as in Figure 8.11, to avoid obscuring\nother features of a given illustration. We will use these \u201cthinner\u201d representations whenever the true view is too\ncrowded to easily visualize.\n"]], ["block_4", [" FIGURE 8.11 \nThis alternate way of drawing the trigonal planar sphybrid orbitals is sometimes used in more\n"]], ["block_5", ["crowded figures.\n"]], ["block_6", ["The observed structure of the borane molecule, BH3, suggests sphybridization for boron in this compound.\nThe molecule is trigonal planar, and the boron atom is involved in three bonds to hydrogen atoms (Figure\n8.12). We can illustrate the comparison of orbitals and electron distribution in an isolated boron atom and in\nthe bonded atom in BH3 as shown in the orbital energy level diagram in Figure 8.13. We redistribute the three\nvalence electrons of the boron atom in the three sphybrid orbitals, and each boron electron pairs with a\nhydrogen electron when B\u2013H bonds form.\n"]], ["block_7", [" FIGURE 8.12 \nBH3 is an electron-deficient molecule with a trigonal planar structure.\n"]], ["block_8", [{"image_1": "396_1.png", "coords": [247, 464, 364, 535]}]], ["block_9", [{"image_2": "396_2.png", "coords": [247, 652, 364, 694]}]], ["block_10", [" 8.2 \u2022 Hybrid Atomic Orbitals \n 383 \n"]]], "page_397": [["block_0", [" 384 \n 8 \u2022 Advanced Theories of Covalent Bonding \n"]], ["block_1", [" sp 3 Hybridization \n"]], ["block_2", ["sphybridized. As we know from the discussion of VSEPR theory, a region of electron density contains all of the\nelectrons that point in one direction. A lone pair, an unpaired electron, a single bond, or a multiple bond would each\ncount as one region of electron density.\n"]], ["block_3", [{"image_0": "397_0.png", "coords": [72, 57, 540, 202]}]], ["block_4", [" FIGURE 8.13 \nIn an isolated B atom, there are one 2s and three 2p valence orbitals. When boron is in a molecule\n"]], ["block_5", ["with three regions of electron density, three of the orbitals hybridize and create a set of three sporbitals and one\nunhybridized 2p orbital. The three half-filled hybrid orbitals each overlap with an orbital from a hydrogen atom to\nform three \u03c3 bonds in BH3.\n"]], ["block_6", ["Any central atom surrounded by three regions of electron density will exhibit sphybridization. This includes\nmolecules with a lone pair on the central atom, such as ClNO (Figure 8.14), or molecules with two single bonds\nand a double bond connected to the central atom, as in formaldehyde, CH2O, and ethene, H2CCH2.\n"]], ["block_7", [" FIGURE 8.14 \nThe central atom(s) in each of the structures shown contain three regions of electron density and are\n"]], ["block_8", ["The valence orbitals of an atom surrounded by a tetrahedral arrangement of bonding pairs and lone pairs\nconsist of a set of four sp 3 hybrid orbitals . The hybrids result from the mixing of one s orbital and all three p\norbitals that produces four identical sphybrid orbitals (Figure 8.15). Each of these hybrid orbitals points\ntoward a different corner of a tetrahedron.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", [{"image_1": "397_1.png", "coords": [189, 306, 423, 354]}]]], "page_398": [["block_0", [{"image_0": "398_0.png", "coords": [72, 57, 540, 459]}]], ["block_1", [" FIGURE 8.15 \nThe hybridization of an s orbital (blue) and three p orbitals (red) produces four equivalent sp\n"]], ["block_2", ["hybridized orbitals (yellow) oriented at 109.5\u00b0 with respect to each other.\n"]], ["block_3", ["A molecule of methane, CH4, consists of a carbon atom surrounded by four hydrogen atoms at the corners of a\ntetrahedron. The carbon atom in methane exhibits sphybridization. We illustrate the orbitals and electron\ndistribution in an isolated carbon atom and in the bonded atom in CH4 in Figure 8.16. The four valence\nelectrons of the carbon atom are distributed equally in the hybrid orbitals, and each carbon electron pairs with\na hydrogen electron when the C\u2013H bonds form.\n"]], ["block_4", [{"image_1": "398_1.png", "coords": [72, 563, 540, 708]}]], ["block_5", [" FIGURE 8.16 \nThe four valence atomic orbitals from an isolated carbon atom all hybridize when the carbon bonds\n"]], ["block_6", [" 8.2 \u2022 Hybrid Atomic Orbitals \n 385 \n"]]], "page_399": [["block_0", [" 386 \n 8 \u2022 Advanced Theories of Covalent Bonding \n"]], ["block_1", [" sp 3 d and sp 3 d 2 Hybridization \n"]], ["block_2", ["in a molecule like CH4 with four regions of electron density. This creates four equivalent sphybridized orbitals.\nOverlap of each of the hybrid orbitals with a hydrogen orbital creates a C\u2013H \u03c3 bond.\n"]], ["block_3", ["In a methane molecule, the 1s orbital of each of the four hydrogen atoms overlaps with one of the four sp\n"]], ["block_4", ["orbitals of the carbon atom to form a sigma (\u03c3) bond. This results in the formation of four strong, equivalent\ncovalent bonds between the carbon atom and each of the hydrogen atoms to produce the methane molecule,\nCH4.\n"]], ["block_5", ["The structure of ethane, C2H6, is similar to that of methane in that each carbon in ethane has four neighboring\natoms arranged at the corners of a tetrahedron\u2014three hydrogen atoms and one carbon atom (Figure 8.17).\nHowever, in ethane an sporbital of one carbon atom overlaps end to end with an sporbital of a second\ncarbon atom to form a \u03c3 bond between the two carbon atoms. Each of the remaining sphybrid orbitals\noverlaps with an s orbital of a hydrogen atom to form carbon\u2013hydrogen \u03c3 bonds. The structure and overall\noutline of the bonding orbitals of ethane are shown in Figure 8.17. The orientation of the two CH3 groups is not\nfixed relative to each other. Experimental evidence shows that rotation around \u03c3 bonds occurs easily.\n"]], ["block_6", [{"image_0": "399_0.png", "coords": [72, 240, 540, 370]}]], ["block_7", [" FIGURE 8.17 \n(a) In the ethane molecule, C2H6, each carbon has four sporbitals. (b) These four orbitals overlap to\n"]], ["block_8", ["form seven \u03c3 bonds.\n"]], ["block_9", ["An sphybrid orbital can also hold a lone pair of electrons. For example, the nitrogen atom in ammonia is\nsurrounded by three bonding pairs and a lone pair of electrons directed to the four corners of a tetrahedron.\nThe nitrogen atom is sphybridized with one hybrid orbital occupied by the lone pair.\n"]], ["block_10", ["The molecular structure of water is consistent with a tetrahedral arrangement of two lone pairs and two\nbonding pairs of electrons. Thus we say that the oxygen atom is sphybridized, with two of the hybrid orbitals\noccupied by lone pairs and two by bonding pairs. Since lone pairs occupy more space than bonding pairs,\nstructures that contain lone pairs have bond angles slightly distorted from the ideal. Perfect tetrahedra have\nangles of 109.5\u00b0, but the observed angles in ammonia (107.3\u00b0) and water (104.5\u00b0) are slightly smaller. Other\nexamples of sphybridization include CCl4, PCl3, and NCl3.\n"]], ["block_11", ["To describe the five bonding orbitals in a trigonal bipyramidal arrangement, we must use five of the valence\nshell atomic orbitals (the s orbital, the three p orbitals, and one of the d orbitals), which gives five sp 3 d hybrid \n orbitals . With an octahedral arrangement of six hybrid orbitals, we must use six valence shell atomic orbitals\n(the s orbital, the three p orbitals, and two of the d orbitals in its valence shell), which gives six sp 3 d 2 hybrid \n orbitals . These hybridizations are only possible for atoms that have d orbitals in their valence subshells (that\nis, not those in the first or second period).\n"]], ["block_12", ["In a molecule of phosphorus pentachloride, PCl5, there are five P\u2013Cl bonds (thus five pairs of valence electrons\naround the phosphorus atom) directed toward the corners of a trigonal bipyramid. We use the 3s orbital, the\nthree 3p orbitals, and one of the 3d orbitals to form the set of five spd hybrid orbitals (Figure 8.19) that are\ninvolved in the P\u2013Cl bonds. Other atoms that exhibit spd hybridization include the sulfur atom in SF4 and the\nchlorine atoms in ClF3 and in\n(The electrons on fluorine atoms are omitted for clarity.)\n"]], ["block_13", [" Access for free at openstax.org \n"]]], "page_400": [["block_0", ["spdorbitals form an octahedral structure around sulfur. Again, the minor lobe of each orbital is not shown for\nclarity.\n"]], ["block_1", [" FIGURE 8.18 \nThe three compounds pictured exhibit spd hybridization in the central atom and a trigonal\n"]], ["block_2", ["bipyramid form. SF4 and\nhave one lone pair of electrons on the central atom, and ClF3 has two lone pairs\n"]], ["block_3", ["giving it the T-shape shown.\n"]], ["block_4", [" FIGURE 8.19 \n(a) The five regions of electron density around phosphorus in PCl5 require five hybrid spd orbitals.\n"]], ["block_5", ["(b) These orbitals combine to form a trigonal bipyramidal structure with each large lobe of the hybrid orbital pointing\nat a vertex. As before, there are also small lobes pointing in the opposite direction for each orbital (not shown for\nclarity).\n"]], ["block_6", ["The sulfur atom in sulfur hexafluoride, SF6, exhibits spdhybridization. A molecule of sulfur hexafluoride has\nsix bonding pairs of electrons connecting six fluorine atoms to a single sulfur atom. There are no lone pairs of\nelectrons on the central atom. To bond six fluorine atoms, the 3s orbital, the three 3p orbitals, and two of the 3d\norbitals form six equivalent spdhybrid orbitals, each directed toward a different corner of an octahedron.\nOther atoms that exhibit spdhybridization include the phosphorus atom in\nthe iodine atom in the\n"]], ["block_7", ["interhalogens\nIF5,\nand the xenon atom in XeF4.\n"]], ["block_8", [" FIGURE 8.20 \n(a) Sulfur hexafluoride, SF6, has an octahedral structure that requires spdhybridization. (b) The six\n"]], ["block_9", [" Assignment of Hybrid Orbitals to Central Atoms \n"]], ["block_10", ["The hybridization of an atom is determined based on the number of regions of electron density that surround\nit. The geometrical arrangements characteristic of the various sets of hybrid orbitals are shown in Figure 8.21.\nThese arrangements are identical to those of the electron-pair geometries predicted by VSEPR theory. VSEPR\ntheory predicts the shapes of molecules, and hybrid orbital theory provides an explanation for how those\nshapes are formed. To find the hybridization of a central atom, we can use the following guidelines:\n"]], ["block_11", ["1.\nDetermine the Lewis structure of the molecule.\n"]], ["block_12", ["2.\nDetermine the number of regions of electron density around an atom using VSEPR theory, in which single\nbonds, multiple bonds, radicals, and lone pairs each count as one region.\n"]], ["block_13", ["3.\nAssign the set of hybridized orbitals from Figure 8.21 that corresponds to this geometry.\n"]], ["block_14", [{"image_0": "400_0.png", "coords": [189, 57, 423, 117]}]], ["block_15", [{"image_1": "400_1.png", "coords": [189, 164, 423, 279]}]], ["block_16", [{"image_2": "400_2.png", "coords": [189, 421, 423, 526]}]], ["block_17", [" 8.2 \u2022 Hybrid Atomic Orbitals \n 387 \n"]]], "page_401": [["block_0", [" 388 \n 8 \u2022 Advanced Theories of Covalent Bonding \n"]], ["block_1", [{"image_0": "401_0.png", "coords": [72, 57, 540, 495]}]], ["block_2", [" FIGURE 8.21 \nThe shapes of hybridized orbital sets are consistent with the electron-pair geometries. For example,\n"]], ["block_3", ["an atom surrounded by three regions of electron density is sphybridized, and the three sporbitals are arranged in\na trigonal planar fashion.\n"]], ["block_4", ["It is important to remember that hybridization was devised to rationalize experimentally observed molecular\ngeometries. The model works well for molecules containing small central atoms, in which the valence electron\npairs are close together in space. However, for larger central atoms, the valence-shell electron pairs are farther\nfrom the nucleus, and there are fewer repulsions. Their compounds exhibit structures that are often not\nconsistent with VSEPR theory, and hybridized orbitals are not necessary to explain the observed data. For\nexample, we have discussed the H\u2013O\u2013H bond angle in H2O, 104.5\u00b0, which is more consistent with sphybrid\norbitals (109.5\u00b0) on the central atom than with 2p orbitals (90\u00b0). Sulfur is in the same group as oxygen, and H2S\nhas a similar Lewis structure. However, it has a much smaller bond angle (92.1\u00b0), which indicates much less\nhybridization on sulfur than oxygen. Continuing down the group, tellurium is even larger than sulfur, and for\nH2Te, the observed bond angle (90\u00b0) is consistent with overlap of the 5p orbitals, without invoking\nhybridization. We invoke hybridization where it is necessary to explain the observed structures.\n"]], ["block_5", [" Access for free at openstax.org \n"]]], "page_402": [["block_0", [{"image_0": "402_0.png", "coords": [72, 57, 540, 178]}]], ["block_1", [" Assigning Hybridization \n"]], ["block_2", ["Ammonium sulfate is important as a fertilizer. What is the hybridization of the sulfur atom in the sulfate ion,\n"]], ["block_3", [" Solution \n"]], ["block_4", ["The Lewis structure of sulfate shows there are four regions of electron density. The hybridization is sp.\n"]], ["block_5", [{"image_1": "402_1.png", "coords": [72, 296, 306, 433]}]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["What is the hybridization of the selenium atom in SeF4?\n"]], ["block_8", [{"image_2": "402_2.png", "coords": [72, 470, 189, 522]}]], ["block_9", [" Answer: \nThe selenium atom is spd hybridized.\n"]], ["block_10", [" Assigning Hybridization \n"]], ["block_11", ["Urea, NH2C(O)NH2, is sometimes used as a source of nitrogen in fertilizers. What is the hybridization of the\ncarbon atom in urea?\n"]], ["block_12", [" Solution \n"]], ["block_13", ["The Lewis structure of urea is\n"]], ["block_14", ["EXAMPLE 8.2\n"]], ["block_15", ["EXAMPLE 8.3\n"]], ["block_16", [" 8.2 \u2022 Hybrid Atomic Orbitals \n 389 \n"]]], "page_403": [["block_0", [" 390 \n 8 \u2022 Advanced Theories of Covalent Bonding \n"]], ["block_1", [{"image_0": "403_0.png", "coords": [72, 57, 189, 114]}]], ["block_2", ["The carbon atom is surrounded by three regions of electron density, positioned in a trigonal planar\narrangement. The hybridization in a trigonal planar electron pair geometry is sp(Figure 8.21), which is the\nhybridization of the carbon atom in urea.\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["Acetic acid, H3CC(O)OH, is the molecule that gives vinegar its odor and sour taste. What is the hybridization of\nthe two carbon atoms in acetic acid?\n"]], ["block_5", [{"image_1": "403_1.png", "coords": [72, 208, 189, 270]}]], ["block_6", [" Answer: \nH3C, sp; C(O)OH, sp\n"]], ["block_7", [" 8.3 Multiple Bonds \n"]], ["block_8", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_9", ["The hybrid orbital model appears to account well for the geometry of molecules involving single covalent\nbonds. Is it also capable of describing molecules containing double and triple bonds? We have already\ndiscussed that multiple bonds consist of \u03c3 and \u03c0 bonds. Next we can consider how we visualize these\ncomponents and how they relate to hybrid orbitals. The Lewis structure of ethene, C2H4, shows us that each\ncarbon atom is surrounded by one other carbon atom and two hydrogen atoms.\n"]], ["block_10", [{"image_2": "403_2.png", "coords": [72, 470, 189, 517]}]], ["block_11", ["The three bonding regions form a trigonal planar electron-pair geometry. Thus we expect the \u03c3 bonds from\neach carbon atom are formed using a set of sphybrid orbitals that result from hybridization of two of the 2p\norbitals and the 2s orbital (Figure 8.22). These orbitals form the C\u2013H single bonds and the \u03c3 bond in the\ndouble bond (Figure 8.23). The \u03c0 bond in the\ndouble bond results from the overlap of the third\n"]], ["block_12", ["(remaining) 2p orbital on each carbon atom that is not involved in hybridization. This unhybridized p orbital\n(lobes shown in red and blue in Figure 8.23) is perpendicular to the plane of the sphybrid orbitals. Thus the\nunhybridized 2p orbitals overlap in a side-by-side fashion, above and below the internuclear axis (Figure 8.23)\nand form a \u03c0 bond.\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", ["\u2022\nDescribe multiple covalent bonding in terms of atomic orbital overlap\n"]], ["block_15", ["\u2022\nRelate the concept of resonance to \u03c0-bonding and electron delocalization\n"]]], "page_404": [["block_0", [{"image_0": "404_0.png", "coords": [72, 57, 540, 202]}]], ["block_1", [" FIGURE 8.22 \nIn ethene, each carbon atom is sphybridized, and the sporbitals and the p orbital are singly\n"]], ["block_2", ["occupied. The hybrid orbitals overlap to form \u03c3 bonds, while the p orbitals on each carbon atom overlap to form a \u03c0\nbond.\n"]], ["block_3", [" FIGURE 8.23 \nIn the ethene molecule, C2H4, there are (a) five \u03c3 bonds. One C\u2013C \u03c3 bond results from overlap of sp\n"]], ["block_4", ["hybrid orbitals on the carbon atom with one sphybrid orbital on the other carbon atom. Four C\u2013H bonds result from\nthe overlap between the C atoms' sporbitals with s orbitals on the hydrogen atoms. (b) The \u03c0 bond is formed by\nthe side-by-side overlap of the two unhybridized p orbitals in the two carbon atoms. The two lobes of the \u03c0 bond are\nabove and below the plane of the \u03c3 system.\n"]], ["block_5", ["In an ethene molecule, the four hydrogen atoms and the two carbon atoms are all in the same plane. If the two\nplanes of sphybrid orbitals tilted relative to each other, the p orbitals would not be oriented to overlap\nefficiently to create the \u03c0 bond. The planar configuration for the ethene molecule occurs because it is the most\nstable bonding arrangement. This is a significant difference between \u03c3 and \u03c0 bonds; rotation around single (\u03c3)\nbonds occurs easily because the end-to-end orbital overlap does not depend on the relative orientation of the\norbitals on each atom in the bond. In other words, rotation around the internuclear axis does not change the\nextent to which the \u03c3 bonding orbitals overlap because the bonding electron density is symmetric about the\naxis. Rotation about the internuclear axis is much more difficult for multiple bonds; however, this would\ndrastically alter the off-axis overlap of the \u03c0 bonding orbitals, essentially breaking the \u03c0 bond.\n"]], ["block_6", ["In molecules with sp hybrid orbitals, two unhybridized p orbitals remain on the atom (Figure 8.24). We find\nthis situation in acetylene,\nwhich is a linear molecule. The sp hybrid orbitals of the two carbon\n"]], ["block_7", ["atoms overlap end to end to form a \u03c3 bond between the carbon atoms (Figure 8.25). The remaining sp orbitals\nform \u03c3 bonds with hydrogen atoms. The two unhybridized p orbitals per carbon are positioned such that they\noverlap side by side and, hence, form two \u03c0 bonds. The two carbon atoms of acetylene are thus bound together\nby one \u03c3 bond and two \u03c0 bonds, giving a triple bond.\n"]], ["block_8", [{"image_1": "404_1.png", "coords": [130, 249, 481, 361]}]], ["block_9", [" 8.3 \u2022 Multiple Bonds \n 391 \n"]]], "page_405": [["block_0", [" 392 \n 8 \u2022 Advanced Theories of Covalent Bonding \n"]], ["block_1", [" FIGURE 8.24 \nDiagram of the two linear sp hybrid orbitals of a carbon atom, which lie in a straight line, and the two\n"]], ["block_2", ["unhybridized p orbitals at perpendicular angles.\n"]], ["block_3", [" FIGURE 8.25 \n(a) In the acetylene molecule, C2H2, there are two C\u2013H \u03c3 bonds and a\ntriple bond involving\n"]], ["block_4", ["one C\u2013C \u03c3 bond and two C\u2013C \u03c0 bonds. The dashed lines, each connecting two lobes, indicate the side-by-side\noverlap of the four unhybridized p orbitals. (b) This shows the overall outline of the bonds in C2H2. The two lobes of\neach of the \u03c0 bonds are positioned across from each other around the line of the C\u2013C \u03c3 bond.\n"]], ["block_5", ["Hybridization involves only \u03c3 bonds, lone pairs of electrons, and single unpaired electrons (radicals).\nStructures that account for these features describe the correct hybridization of the atoms. However, many\nstructures also include resonance forms. Remember that resonance forms occur when various arrangements\nof \u03c0 bonds are possible. Since the arrangement of \u03c0 bonds involves only the unhybridized orbitals, resonance\ndoes not influence the assignment of hybridization.\n"]], ["block_6", ["For example, molecule benzene has two resonance forms (Figure 8.26). We can use either of these forms to\ndetermine that each of the carbon atoms is bonded to three other atoms with no lone pairs, so the correct\nhybridization is sp. The electrons in the unhybridized p orbitals form \u03c0 bonds. Neither resonance structure\ncompletely describes the electrons in the \u03c0 bonds. They are not located in one position or the other, but in\nreality are delocalized throughout the ring. Valence bond theory does not easily address delocalization.\nBonding in molecules with resonance forms is better described by molecular orbital theory. (See the next\nmodule.)\n"]], ["block_7", [" FIGURE 8.26 \nEach carbon atom in benzene, C6H6, is sphybridized, independently of which resonance form is\n"]], ["block_8", ["considered. The electrons in the \u03c0 bonds are not located in one set of p orbitals or the other, but rather delocalized\nthroughout the molecule.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", [{"image_0": "405_0.png", "coords": [130, 204, 481, 316]}]], ["block_11", [{"image_1": "405_1.png", "coords": [189, 57, 423, 169]}]], ["block_12", [{"image_2": "405_2.png", "coords": [189, 540, 423, 632]}]]], "page_406": [["block_0", [" Answer: \nsp\n"]], ["block_1", [" Assignment of Hybridization Involving Resonance \n"]], ["block_2", ["Some acid rain results from the reaction of sulfur dioxide with atmospheric water vapor, followed by the\nformation of sulfuric acid. Sulfur dioxide, SO2, is a major component of volcanic gases as well as a product of\nthe combustion of sulfur-containing coal. What is the hybridization of the S atom in SO2?\n"]], ["block_3", [" Solution \n"]], ["block_4", ["The resonance structures of SO2 are\n"]], ["block_5", [{"image_0": "406_0.png", "coords": [72, 184, 306, 217]}]], ["block_6", ["The sulfur atom is surrounded by two bonds and one lone pair of electrons in either resonance structure.\nTherefore, the electron-pair geometry is trigonal planar, and the hybridization of the sulfur atom is sp.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["Another acid in acid rain is nitric acid, HNO3, which is produced by the reaction of nitrogen dioxide, NO2, with\natmospheric water vapor. What is the hybridization of the nitrogen atom in NO2? (Note: the lone electron on\nnitrogen occupies a hybridized orbital just as a lone pair would.)\n"]], ["block_9", [" 8.4 Molecular Orbital Theory \n"]], ["block_10", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_11", ["For almost every covalent molecule that exists, we can now draw the Lewis structure, predict the electron-pair\ngeometry, predict the molecular geometry, and come close to predicting bond angles. However, one of the most\nimportant molecules we know, the oxygen molecule O2, presents a problem with respect to its Lewis structure.\nWe would write the following Lewis structure for O2:\n"]], ["block_12", [{"image_1": "406_1.png", "coords": [72, 537, 189, 554]}]], ["block_13", ["This electronic structure adheres to all the rules governing Lewis theory. There is an O=O double bond, and\neach oxygen atom has eight electrons around it. However, this picture is at odds with the magnetic behavior of\noxygen. By itself, O2 is not magnetic, but it is attracted to magnetic fields. Thus, when we pour liquid oxygen\npast a strong magnet, it collects between the poles of the magnet and defies gravity, as in Figure 8.1. Such\nattraction to a magnetic field is called paramagnetism , and it arises in molecules that have unpaired\nelectrons. And yet, the Lewis structure of O2 indicates that all electrons are paired. How do we account for this\ndiscrepancy?\n"]], ["block_14", ["Magnetic susceptibility measures the force experienced by a substance in a magnetic field. When we compare\nthe weight of a sample to the weight measured in a magnetic field (Figure 8.27), paramagnetic samples that are\nattracted to the magnet will appear heavier because of the force exerted by the magnetic field. We can calculate\nthe number of unpaired electrons based on the increase in weight.\n"]], ["block_15", ["\u2022\nOutline the basic quantum-mechanical approach to deriving molecular orbitals from atomic orbitals\n"]], ["block_16", ["\u2022\nDescribe traits of bonding and antibonding molecular orbitals\n"]], ["block_17", ["\u2022\nCalculate bond orders based on molecular electron configurations\n"]], ["block_18", ["\u2022\nWrite molecular electron configurations for first- and second-row diatomic molecules\n"]], ["block_19", ["\u2022\nRelate these electron configurations to the molecules\u2019 stabilities and magnetic properties\n"]], ["block_20", ["EXAMPLE 8.4\n"]], ["block_21", [" 8.4 \u2022 Molecular Orbital Theory \n 393 \n"]]], "page_407": [["block_0", [" 394 \n 8 \u2022 Advanced Theories of Covalent Bonding \n"]], ["block_1", [" FIGURE 8.27 \nA Gouy balance compares the mass of a sample in the presence of a magnetic field with the mass\n"]], ["block_2", ["with the electromagnet turned off to determine the number of unpaired electrons in a sample.\n"]], ["block_3", ["Experiments show that each O2 molecule has two unpaired electrons. The Lewis-structure model does not\npredict the presence of these two unpaired electrons. Unlike oxygen, the apparent weight of most molecules\ndecreases slightly in the presence of an inhomogeneous magnetic field. Materials in which all of the electrons\nare paired are diamagnetic and weakly repel a magnetic field. Paramagnetic and diamagnetic materials do not\nact as permanent magnets. Only in the presence of an applied magnetic field do they demonstrate attraction or\nrepulsion.\n"]], ["block_4", ["Water, like most molecules, contains all paired electrons. Living things contain a large percentage of water, so\nthey demonstrate diamagnetic behavior. If you place a frog near a sufficiently large magnet, it will levitate. You\ncan see videos (http://openstax.org/l/16diamagnetic) of diamagnetic floating frogs, strawberries, and more.\n"]], ["block_5", ["Molecular orbital theory (MO theory) provides an explanation of chemical bonding that accounts for the\nparamagnetism of the oxygen molecule. It also explains the bonding in a number of other molecules, such as\nviolations of the octet rule and more molecules with more complicated bonding (beyond the scope of this text)\nthat are difficult to describe with Lewis structures. Additionally, it provides a model for describing the energies\nof electrons in a molecule and the probable location of these electrons. Unlike valence bond theory, which uses\nhybrid orbitals that are assigned to one specific atom, MO theory uses the combination of atomic orbitals to\nyield molecular orbitals that are delocalized over the entire molecule rather than being localized on its\nconstituent atoms. MO theory also helps us understand why some substances are electrical conductors, others\nare semiconductors, and still others are insulators. Table 8.2 summarizes the main points of the two\ncomplementary bonding theories. Both theories provide different, useful ways of describing molecular\nstructure.\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", ["LINK TO LEARNING\n"]], ["block_8", [{"image_0": "407_0.png", "coords": [130, 57, 481, 321]}]]], "page_408": [["block_0", [" TABLE 8.2 \n"]], ["block_1", [" Molecular orbital theory describes the distribution of electrons in molecules in much the same way that the\ndistribution of electrons in atoms is described using atomic orbitals. Using quantum mechanics, the behavior\nof an electron in a molecule is still described by a wave function, \u03a8, analogous to the behavior in an atom. Just\nlike electrons around isolated atoms, electrons around atoms in molecules are limited to discrete (quantized)\nenergies. The region of space in which a valence electron in a molecule is likely to be found is called a\n molecular orbital ( \u03a8 2 ) . Like an atomic orbital, a molecular orbital is full when it contains two electrons with\nopposite spin.\n"]], ["block_2", ["We will consider the molecular orbitals in molecules composed of two identical atoms (H2 or Cl2, for example).\nSuch molecules are called homonuclear diatomic molecules . In these diatomic molecules, several types of\nmolecular orbitals occur.\n"]], ["block_3", ["The mathematical process of combining atomic orbitals to generate molecular orbitals is called the linear \n combination of atomic orbitals (LCAO) . The wave function describes the wavelike properties of an electron.\nMolecular orbitals are combinations of atomic orbital wave functions. Combining waves can lead to\nconstructive interference, in which peaks line up with peaks, or destructive interference, in which peaks line\nup with troughs (Figure 8.28). In orbitals, the waves are three dimensional, and they combine with in-phase\nwaves producing regions with a higher probability of electron density and out-of-phase waves producing\nnodes, or regions of no electron density.\n"]], ["block_4", [{"image_0": "408_0.png", "coords": [72, 553, 540, 652]}]], ["block_5", [" FIGURE 8.28 \n(a) When in-phase waves combine, constructive interference produces a wave with greater\n"]], ["block_6", ["amplitude. (b) When out-of-phase waves combine, destructive interference produces a wave with less (or no)\namplitude.\n"]], ["block_7", ["There are two types of molecular orbitals that can form from the overlap of two atomic s orbitals on adjacent\natoms. The two types are illustrated in Figure 8.29. The in-phase combination produces a lower energy \u03c3 s \n"]], ["block_8", [" Valence Bond Theory \n Molecular Orbital Theory \n"]], ["block_9", ["considers bonds as localized between one pair of\natoms\n"]], ["block_10", ["creates bonds from overlap of atomic orbitals (s, p, d\u2026)\nand hybrid orbitals (sp, sp, sp\u2026)\n"]], ["block_11", ["forms \u03c3 or \u03c0 bonds\ncreates bonding and antibonding interactions\nbased on which orbitals are filled\n"]], ["block_12", ["predicts molecular shape based on the number of\nregions of electron density\n"]], ["block_13", ["needs multiple structures to describe resonance\n"]], ["block_14", ["Comparison of Bonding Theories\n"]], ["block_15", ["considers electrons delocalized throughout the\nentire molecule\n"]], ["block_16", ["combines atomic orbitals to form molecular\norbitals (\u03c3, \u03c3*, \u03c0, \u03c0*)\n"]], ["block_17", ["predicts the arrangement of electrons in\nmolecules\n"]], ["block_18", [" 8.4 \u2022 Molecular Orbital Theory \n 395 \n"]]], "page_409": [["block_0", [" 396 \n 8 \u2022 Advanced Theories of Covalent Bonding \n"]], ["block_1", [" molecular orbital (read as \"sigma-s\") in which most of the electron density is directly between the nuclei. The\nout-of-phase addition (which can also be thought of as subtracting the wave functions) produces a higher\nenergy\n molecular orbital (read as \"sigma-s-star\") molecular orbital in which there is a node between the\n"]], ["block_2", ["nuclei. The asterisk signifies that the orbital is an antibonding orbital. Electrons in a \u03c3s orbital are attracted by\nboth nuclei at the same time and are more stable (of lower energy) than they would be in the isolated atoms.\nAdding electrons to these orbitals creates a force that holds the two nuclei together, so we call these orbitals\n bonding orbitals . Electrons in the\norbitals are located well away from the region between the two nuclei.\n"]], ["block_3", ["The attractive force between the nuclei and these electrons pulls the two nuclei apart. Hence, these orbitals are\ncalled antibonding orbitals . Electrons fill the lower-energy bonding orbital before the higher-energy\nantibonding orbital, just as they fill lower-energy atomic orbitals before they fill higher-energy atomic orbitals.\n"]], ["block_4", [" FIGURE 8.29 \nSigma (\u03c3) and sigma-star (\u03c3*) molecular orbitals are formed by the combination of two s atomic\n"]], ["block_5", ["orbitals. The dots (\u00b7) indicate the locations of nuclei.\n"]], ["block_6", ["You can watch animations (http://openstax.org/l/16molecorbital) visualizing the calculated atomic orbitals\ncombining to form various molecular orbitals at the Orbitron website.\n"]], ["block_7", ["In p orbitals, the wave function gives rise to two lobes with opposite phases, analogous to how a two-\ndimensional wave has both parts above and below the average. We indicate the phases by shading the orbital\nlobes different colors. When orbital lobes of the same phase overlap, constructive wave interference increases\nthe electron density. When regions of opposite phase overlap, the destructive wave interference decreases\nelectron density and creates nodes. When p orbitals overlap end to end, they create \u03c3 and \u03c3* orbitals (Figure\n8.30). If two atoms are located along the x-axis in a Cartesian coordinate system, the two px orbitals overlap\nend to end and form \u03c3px (bonding) and\n(antibonding) (read as \"sigma-p-x\" and \"sigma-p-x star,\"\n"]], ["block_8", ["respectively). Just as with s-orbital overlap, the asterisk indicates the orbital with a node between the nuclei,\nwhich is a higher-energy, antibonding orbital.\n"]], ["block_9", [" FIGURE 8.30 \nCombining wave functions of two p atomic orbitals along the internuclear axis creates two molecular\n"]], ["block_10", ["orbitals, \u03c3 p and\n"]], ["block_11", ["The side-by-side overlap of two p orbitals gives rise to a pi (\u03c0) bonding molecular orbital and a \u03c0* \n antibonding molecular orbital , as shown in Figure 8.31. In valence bond theory, we describe \u03c0 bonds as\ncontaining a nodal plane containing the internuclear axis and perpendicular to the lobes of the p orbitals, with\nelectron density on either side of the node. In molecular orbital theory, we describe the \u03c0 orbital by this same\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["LINK TO LEARNING\n"]], ["block_14", [{"image_0": "409_0.png", "coords": [130, 189, 481, 332]}]], ["block_15", [{"image_1": "409_1.png", "coords": [130, 553, 481, 647]}]]], "page_410": [["block_0", ["shape, and a \u03c0 bond exists when this orbital contains electrons. Electrons in this orbital interact with both\nnuclei and help hold the two atoms together, making it a bonding orbital. For the out-of-phase combination,\nthere are two nodal planes created, one along the internuclear axis and a perpendicular one between the\nnuclei.\n"]], ["block_1", [" FIGURE 8.31 \nSide-by-side overlap of each two p orbitals results in the formation of two \u03c0 molecular orbitals.\n"]], ["block_2", ["Combining the out-of-phase orbitals results in an antibonding molecular orbital with two nodes. One contains the\ninternuclear axis, and one is perpendicular to the axis. Combining the in-phase orbitals results in a bonding orbital.\nThere is a node (blue) containing the internuclear axis with the two lobes of the orbital located above and below this\nnode.\n"]], ["block_3", ["In the molecular orbitals of diatomic molecules, each atom also has two sets of p orbitals oriented side by side\n(py and pz), so these four atomic orbitals combine pairwise to create two \u03c0 orbitals and two \u03c0* orbitals. The \u03c0py\nand\norbitals are oriented at right angles to the \u03c0pz and\norbitals. Except for their orientation, the \u03c0py and\n"]], ["block_4", ["\u03c0pz orbitals are identical and have the same energy; they are degenerate orbitals . The\nand\n"]], ["block_5", ["antibonding orbitals are also degenerate and identical except for their orientation. A total of six molecular\norbitals results from the combination of the six atomic p orbitals in two atoms: \u03c3px and\n\u03c0py and\n\u03c0pz\n"]], ["block_6", ["and\n"]], ["block_7", [" Molecular Orbitals \n"]], ["block_8", ["Predict what type (if any) of molecular orbital would result from adding the wave functions so each pair of\norbitals shown overlap. The orbitals are all similar in energy.\n"]], ["block_9", [{"image_0": "410_0.png", "coords": [72, 549, 432, 661]}]], ["block_10", [" Solution \n"]], ["block_11", ["(a) is an in-phase combination, resulting in a \u03c33p orbital\n"]], ["block_12", ["(b) will not result in a new orbital because the in-phase component (bottom) and out-of-phase component (top)\ncancel out. Only orbitals with the correct alignment can combine.\n"]], ["block_13", ["EXAMPLE 8.5\n"]], ["block_14", [{"image_1": "410_1.png", "coords": [189, 114, 423, 298]}]], ["block_15", [" 8.4 \u2022 Molecular Orbital Theory \n 397 \n"]]], "page_411": [["block_0", [" 398 \n 8 \u2022 Advanced Theories of Covalent Bonding \n"]], ["block_1", ["(c) is an out-of-phase combination, resulting in a\norbital.\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["Label the molecular orbital shown as \u03c3 or \u03c0, bonding or antibonding and indicate where the node occurs.\n"]], ["block_4", [{"image_0": "411_0.png", "coords": [72, 113, 306, 137]}]], ["block_5", [" Answer: \nThe orbital is located along the internuclear axis, so it is a \u03c3 orbital. There is a node bisecting the internuclear\naxis, so it is an antibonding orbital.\n"]], ["block_6", [{"image_1": "411_1.png", "coords": [72, 187, 306, 211]}]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", ["Portrait of a Chemist\n"]], ["block_9", [" Walter Kohn: Nobel Laureate \nWalter Kohn (Figure 8.32) is a theoretical physicist who studies the electronic structure of solids. His work\ncombines the principles of quantum mechanics with advanced mathematical techniques. This technique,\ncalled density functional theory, makes it possible to compute properties of molecular orbitals, including\ntheir shape and energies. Kohn and mathematician John Pople were awarded the Nobel Prize in Chemistry\nin 1998 for their contributions to our understanding of electronic structure. Kohn also made significant\ncontributions to the physics of semiconductors.\n"]], ["block_10", [" FIGURE 8.32 \nWalter Kohn developed methods to describe molecular orbitals. (credit: image courtesy of Walter\n"]], ["block_11", ["Kohn)\n"]], ["block_12", ["Kohn\u2019s biography has been remarkable outside the realm of physical chemistry as well. He was born in\nAustria, and during World War II he was part of the Kindertransport program that rescued 10,000 children\nfrom the Nazi regime. His summer jobs included discovering gold deposits in Canada and helping Polaroid\nexplain how its instant film worked. Dr. Kohn passed away in 2016 at the age of 93.\n"]], ["block_13", [{"image_2": "411_2.png", "coords": [189, 351, 423, 624]}]]], "page_412": [["block_0", [" Computational Chemistry in Drug Design \nWhile the descriptions of bonding described in this chapter involve many theoretical concepts, they also have\nmany practical, real-world applications. For example, drug design is an important field that uses our\nunderstanding of chemical bonding to develop pharmaceuticals. This interdisciplinary area of study uses\nbiology (understanding diseases and how they operate) to identify specific targets, such as a binding site that is\ninvolved in a disease pathway. By modeling the structures of the binding site and potential drugs,\ncomputational chemists can predict which structures can fit together and how effectively they will bind (see\nFigure 8.33). Thousands of potential candidates can be narrowed down to a few of the most promising\ncandidates. These candidate molecules are then carefully tested to determine side effects, how effectively they\ncan be transported through the body, and other factors. Dozens of important new pharmaceuticals have been\ndiscovered with the aid of computational chemistry, and new research projects are underway.\n"]], ["block_1", [" FIGURE 8.33 \nThe molecule shown, HIV-1 protease, is an important target for pharmaceutical research. By\n"]], ["block_2", ["designing molecules that bind to this protein, scientists are able to drastically inhibit the progress of the disease.\n"]], ["block_3", [" Molecular Orbital Energy Diagrams \n"]], ["block_4", ["The relative energy levels of atomic and molecular orbitals are typically shown in a molecular orbital diagram \n(Figure 8.34). For a diatomic molecule, the atomic orbitals of one atom are shown on the left, and those of the\nother atom are shown on the right. Each horizontal line represents one orbital that can hold two electrons. The\nmolecular orbitals formed by the combination of the atomic orbitals are shown in the center. Dashed lines\nshow which of the atomic orbitals combine to form the molecular orbitals. For each pair of atomic orbitals that\ncombine, one lower-energy (bonding) molecular orbital and one higher-energy (antibonding) orbital result.\nThus we can see that combining the six 2p atomic orbitals results in three bonding orbitals (one \u03c3 and two \u03c0)\nand three antibonding orbitals (one \u03c3* and two \u03c0*).\n"]], ["block_5", ["We predict the distribution of electrons in these molecular orbitals by filling the orbitals in the same way that\nwe fill atomic orbitals, by the Aufbau principle. Lower-energy orbitals fill first, electrons spread out among\ndegenerate orbitals before pairing, and each orbital can hold a maximum of two electrons with opposite spins\n(Figure 8.34). Just as we write electron configurations for atoms, we can write the molecular electronic\nconfiguration by listing the orbitals with superscripts indicating the number of electrons present. For clarity,\nwe place parentheses around molecular orbitals with the same energy. In this case, each orbital is at a different\nenergy, so parentheses separate each orbital. Thus we would expect a diatomic molecule or ion containing\nseven electrons (such as\nwould have the molecular electron configuration\nIt\n"]], ["block_6", ["is common to omit the core electrons from molecular orbital diagrams and configurations and include only the\nvalence electrons.\n"]], ["block_7", ["HOW SCIENCES INTERCONNECT\n"]], ["block_8", [{"image_0": "412_0.png", "coords": [189, 236, 423, 363]}]], ["block_9", [" 8.4 \u2022 Molecular Orbital Theory \n 399 \n"]]], "page_413": [["block_0", [" 400 \n 8 \u2022 Advanced Theories of Covalent Bonding \n"]], ["block_1", [{"image_0": "413_0.png", "coords": [72, 57, 540, 176]}]], ["block_2", [" FIGURE 8.34 \nThis is the molecular orbital diagram for the homonuclear diatomic\nshowing the molecular\n"]], ["block_3", ["orbitals of the valence shell only. The molecular orbitals are filled in the same manner as atomic orbitals, using the\nAufbau principle and Hund\u2019s rule.\n"]], ["block_4", [" Bond Order \n"]], ["block_5", ["The filled molecular orbital diagram shows the number of electrons in both bonding and antibonding\nmolecular orbitals. The net contribution of the electrons to the bond strength of a molecule is identified by\ndetermining the bond order that results from the filling of the molecular orbitals by electrons.\n"]], ["block_6", ["When using Lewis structures to describe the distribution of electrons in molecules, we define bond order as\nthe number of bonding pairs of electrons between two atoms. Thus a single bond has a bond order of 1, a\ndouble bond has a bond order of 2, and a triple bond has a bond order of 3. We define bond order differently\nwhen we use the molecular orbital description of the distribution of electrons, but the resulting bond order is\nusually the same. The MO technique is more accurate and can handle cases when the Lewis structure method\nfails, but both methods describe the same phenomenon.\n"]], ["block_7", ["In the molecular orbital model, an electron contributes to a bonding interaction if it occupies a bonding orbital\nand it contributes to an antibonding interaction if it occupies an antibonding orbital. The bond order is\ncalculated by subtracting the destabilizing (antibonding) electrons from the stabilizing (bonding) electrons.\nSince a bond consists of two electrons, we divide by two to get the bond order. We can determine bond order\nwith the following equation:\n"]], ["block_8", ["The order of a covalent bond is a guide to its strength; a bond between two given atoms becomes stronger as\nthe bond order increases (Table 8.1). If the distribution of electrons in the molecular orbitals between two\natoms is such that the resulting bond would have a bond order of zero, a stable bond does not form. We next\nlook at some specific examples of MO diagrams and bond orders.\n"]], ["block_9", [" Bonding in Diatomic Molecules \n"]], ["block_10", ["A dihydrogen molecule (H2) forms from two hydrogen atoms. When the atomic orbitals of the two atoms\ncombine, the electrons occupy the molecular orbital of lowest energy, the \u03c31s bonding orbital. A dihydrogen\nmolecule, H2, readily forms because the energy of a H2 molecule is lower than that of two H atoms. The \u03c31s\norbital that contains both electrons is lower in energy than either of the two 1s atomic orbitals.\n"]], ["block_11", ["A molecular orbital can hold two electrons, so both electrons in the H2 molecule are in the \u03c31s bonding orbital;\nthe electron configuration is\nWe represent this configuration by a molecular orbital energy diagram\n"]], ["block_12", ["(Figure 8.35) in which a single upward arrow indicates one electron in an orbital, and two (upward and\ndownward) arrows indicate two electrons of opposite spin.\n"]], ["block_13", [" Access for free at openstax.org \n"]]], "page_414": [["block_0", [{"image_0": "414_0.png", "coords": [72, 57, 540, 192]}]], ["block_1", [" FIGURE 8.35 \nThe molecular orbital energy diagram predicts that H2 will be a stable molecule with lower energy\n"]], ["block_2", ["than the separated atoms.\n"]], ["block_3", ["A dihydrogen molecule contains two bonding electrons and no antibonding electrons so we have\n"]], ["block_4", ["Because the bond order for the H\u2013H bond is equal to 1, the bond is a single bond.\n"]], ["block_5", ["A helium atom has two electrons, both of which are in its 1s orbital. Two helium atoms do not combine to form\na dihelium molecule, He2, with four electrons, because the stabilizing effect of the two electrons in the lower-\nenergy bonding orbital would be offset by the destabilizing effect of the two electrons in the higher-energy\nantibonding molecular orbital. We would write the hypothetical electron configuration of He2 as\n"]], ["block_6", ["as in Figure 8.36. The net energy change would be zero, so there is no driving force for helium atoms to form\nthe diatomic molecule. In fact, helium exists as discrete atoms rather than as diatomic molecules. The bond\norder in a hypothetical dihelium molecule would be zero.\n"]], ["block_7", ["A bond order of zero indicates that no bond is formed between two atoms.\n"]], ["block_8", [{"image_1": "414_1.png", "coords": [72, 437, 540, 595]}]], ["block_9", [" FIGURE 8.36 \nThe molecular orbital energy diagram predicts that He2 will not be a stable molecule, since it has\n"]], ["block_10", ["equal numbers of bonding and antibonding electrons.\n"]], ["block_11", [" The Diatomic Molecules of the Second Period \nEight possible homonuclear diatomic molecules might be formed by the atoms of the second period of the\nperiodic table: Li2, Be2, B2, C2, N2, O2, F2, and Ne2. However, we can predict that the Be2 molecule and the Ne2\nmolecule would not be stable. We can see this by a consideration of the molecular electron configurations\n(Table 8.3).\n"]], ["block_12", ["We predict valence molecular orbital electron configurations just as we predict electron configurations of\natoms. Valence electrons are assigned to valence molecular orbitals with the lowest possible energies.\n"]], ["block_13", [" 8.4 \u2022 Molecular Orbital Theory \n 401 \n"]]], "page_415": [["block_0", [" 402 \n 8 \u2022 Advanced Theories of Covalent Bonding \n"]], ["block_1", ["Consistent with Hund\u2019s rule, whenever there are two or more degenerate molecular orbitals, electrons fill each\norbital of that type singly before any pairing of electrons takes place.\n"]], ["block_2", ["As we saw in valence bond theory, \u03c3 bonds are generally more stable than \u03c0 bonds formed from degenerate\natomic orbitals. Similarly, in molecular orbital theory, \u03c3 orbitals are usually more stable than \u03c0 orbitals.\nHowever, this is not always the case. The MOs for the valence orbitals of the second period are shown in Figure\n8.37. Looking at Ne2 molecular orbitals, we see that the order is consistent with the generic diagram shown in\nthe previous section. However, for atoms with three or fewer electrons in the p orbitals (Li through N) we\nobserve a different pattern, in which the \u03c3p orbital is higher in energy than the \u03c0p set. Obtain the molecular\norbital diagram for a homonuclear diatomic ion by adding or subtracting electrons from the diagram for the\nneutral molecule.\n"]], ["block_3", [{"image_0": "415_0.png", "coords": [72, 196, 540, 386]}]], ["block_4", [" FIGURE 8.37 \nThis shows the MO diagrams for each homonuclear diatomic molecule in the second period. The\n"]], ["block_5", ["orbital energies decrease across the period as the effective nuclear charge increases and atomic radius decreases.\nBetween N2 and O2, the order of the orbitals changes.\n"]], ["block_6", ["This switch in orbital ordering occurs because of a phenomenon called s-p mixing . s-p mixing does not create\nnew orbitals; it merely influences the energies of the existing molecular orbitals. The \u03c3s wavefunction\nmathematically combines with the \u03c3p wavefunction, with the result that the \u03c3s orbital becomes more stable,\nand the \u03c3p orbital becomes less stable (Figure 8.38). Similarly, the antibonding orbitals also undergo s-p\nmixing, with the \u03c3s* becoming more stable and the \u03c3p* becoming less stable.\n"]], ["block_7", [" Access for free at openstax.org \n"]]], "page_416": [["block_0", [{"image_0": "416_0.png", "coords": [72, 57, 540, 371]}]], ["block_1", [" FIGURE 8.38 \nWithout mixing, the MO pattern occurs as expected, with the \u03c3p orbital lower in energy than the \u03c0p\n"]], ["block_2", ["orbitals. When s-p mixing occurs, the orbitals shift as shown, with the \u03c3p orbital higher in energy than the \u03c0p orbitals.\n"]], ["block_3", ["s-p mixing occurs when the s and p orbitals have similar energies. The energy difference between 2s and 2p\norbitals in O, F, and Ne is greater than that in Li, Be, B, C, and N. Because of this, O2, F2, and Ne2 exhibit\nnegligible s-p mixing (not sufficient to change the energy ordering), and their MO diagrams follow the normal\npattern, as shown in Figure 8.37. All of the other period 2 diatomic molecules do have s-p mixing, which leads\nto the pattern where the \u03c3p orbital is raised above the \u03c0p set.\n"]], ["block_4", ["Using the MO diagrams shown in Figure 8.37, we can add in the electrons and determine the molecular\nelectron configuration and bond order for each of the diatomic molecules. As shown in Table 8.3, Be2 and Ne2\nmolecules would have a bond order of 0, and these molecules do not exist.\n"]], ["block_5", [" TABLE 8.3 \n"]], ["block_6", [" Molecule \n Electron Configuration \n Bond Order \n"]], ["block_7", ["Li2\n1\n"]], ["block_8", ["Be2 (unstable)\n0\n"]], ["block_9", ["B2\n1\n"]], ["block_10", ["C2\n2\n"]], ["block_11", ["Electron Configuration and Bond Order for Molecular Orbitals in Homonuclear Diatomic Molecules of\n"]], ["block_12", ["Period Two Elements\n"]], ["block_13", [" 8.4 \u2022 Molecular Orbital Theory \n 403 \n"]]], "page_417": [["block_0", [" 404 \n 8 \u2022 Advanced Theories of Covalent Bonding \n"]], ["block_1", [" TABLE 8.3 \n"]], ["block_2", ["The combination of two lithium atoms to form a lithium molecule, Li2, is analogous to the formation of H2, but\nthe atomic orbitals involved are the valence 2s orbitals. Each of the two lithium atoms has one valence\nelectron. Hence, we have two valence electrons available for the \u03c32s bonding molecular orbital. Because both\nvalence electrons would be in a bonding orbital, we would predict the Li2 molecule to be stable. The molecule\nis, in fact, present in appreciable concentration in lithium vapor at temperatures near the boiling point of the\nelement. All of the other molecules in Table 8.3 with a bond order greater than zero are also known.\n"]], ["block_3", ["The O2 molecule has enough electrons to half fill the\nlevel. We expect the two electrons that\n"]], ["block_4", ["occupy these two degenerate orbitals to be unpaired, and this molecular electronic configuration for O2 is in\naccord with the fact that the oxygen molecule has two unpaired electrons (Figure 8.40). The presence of two\nunpaired electrons has proved to be difficult to explain using Lewis structures, but the molecular orbital\ntheory explains it quite well. In fact, the unpaired electrons of the oxygen molecule provide a strong piece of\nsupport for the molecular orbital theory.\n"]], ["block_5", [" Band Theory \nWhen two identical atomic orbitals on different atoms combine, two molecular orbitals result (see Figure 8.29).\nThe bonding orbital is lower in energy than the original atomic orbitals because the atomic orbitals are in-\nphase in the molecular orbital. The antibonding orbital is higher in energy than the original atomic orbitals\nbecause the atomic orbitals are out-of-phase.\n"]], ["block_6", ["In a solid, similar things happen, but on a much larger scale. Remember that even in a small sample there are\na huge number of atoms (typically > 10atoms), and therefore a huge number of atomic orbitals that may be\ncombined into molecular orbitals. When N valence atomic orbitals, all of the same energy and each containing\none (1) electron, are combined, N/2 (filled) bonding orbitals and N/2 (empty) antibonding orbitals will result.\nEach bonding orbital will show an energy lowering as the atomic orbitals are mostly in-phase, but each of the\nbonding orbitals will be a little different and have slightly different energies. The antibonding orbitals will\nshow an increase in energy as the atomic orbitals are mostly out-of-phase, but each of the antibonding orbitals\nwill also be a little different and have slightly different energies. The allowed energy levels for all the bonding\norbitals are so close together that they form a band, called the valence band. Likewise, all the antibonding\norbitals are very close together and form a band, called the conduction band. Figure 8.39 shows the bands for\nthree important classes of materials: insulators, semiconductors, and conductors.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [" Molecule \n Electron Configuration \n Bond Order \n"]], ["block_9", ["N2\n3\n"]], ["block_10", ["O2\n2\n"]], ["block_11", ["F2\n1\n"]], ["block_12", ["Ne2 (unstable)\n0\n"]], ["block_13", ["HOW SCIENCES INTERCONNECT\n"]]], "page_418": [["block_0", [" FIGURE 8.39 \nMolecular orbitals in solids are so closely spaced that they are described as bands. The valence band\n"]], ["block_1", ["is lower in energy and the conduction band is higher in energy. The type of solid is determined by the size of the\n\u201cband gap\u201d between the valence and conduction bands. Only a very small amount of energy is required to move\nelectrons from the valence band to the conduction band in a conductor, and so they conduct electricity well. In an\ninsulator, the band gap is large, so that very few electrons move, and they are poor conductors of electricity.\nSemiconductors are in between: they conduct electricity better than insulators, but not as well as conductors.\n"]], ["block_2", ["In order to conduct electricity, electrons must move from the filled valence band to the empty conduction band\nwhere they can move throughout the solid. The size of the band gap, or the energy difference between the top\nof the valence band and the bottom of the conduction band, determines how easy it is to move electrons\nbetween the bands. Only a small amount of energy is required in a conductor because the band gap is very\nsmall. This small energy difference is \u201ceasy\u201d to overcome, so they are good conductors of electricity. In an\ninsulator, the band gap is so \u201clarge\u201d that very few electrons move into the conduction band; as a result,\ninsulators are poor conductors of electricity. Semiconductors conduct electricity when \u201cmoderate\u201d amounts of\nenergy are provided to move electrons out of the valence band and into the conduction band. Semiconductors,\nsuch as silicon, are found in many electronics.\n"]], ["block_3", ["Semiconductors are used in devices such as computers, smartphones, and solar cells. Solar cells produce\nelectricity when light provides the energy to move electrons out of the valence band. The electricity that is\ngenerated may then be used to power a light or tool, or it can be stored for later use by charging a battery. As of\nDecember 2014, up to 46% of the energy in sunlight could be converted into electricity using solar cells.\n"]], ["block_4", [" Molecular Orbital Diagrams, Bond Order, and Number of Unpaired Electrons \n"]], ["block_5", ["Draw the molecular orbital diagram for the oxygen molecule, O2. From this diagram, calculate the bond order\nfor O2. How does this diagram account for the paramagnetism of O2?\n"]], ["block_6", [" Solution \n"]], ["block_7", ["We draw a molecular orbital energy diagram similar to that shown in Figure 8.37. Each oxygen atom\ncontributes six electrons, so the diagram appears as shown in Figure 8.40.\n"]], ["block_8", ["EXAMPLE 8.6\n"]], ["block_9", [{"image_0": "418_0.png", "coords": [130, 57, 481, 193]}]], ["block_10", [" 8.4 \u2022 Molecular Orbital Theory \n 405 \n"]]], "page_419": [["block_0", [" 406 \n 8 \u2022 Advanced Theories of Covalent Bonding \n"]], ["block_1", ["We calculate the bond order as\n"]], ["block_2", ["Oxygen's paramagnetism is explained by the presence of two unpaired electrons in the (\u03c02py, \u03c02pz)* molecular\norbitals.\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["The main component of air is N2. From the molecular orbital diagram of N2, predict its bond order and\nwhether it is diamagnetic or paramagnetic.\n"]], ["block_5", [" Answer: \nN2 has a bond order of 3 and is diamagnetic.\n"]], ["block_6", [" Ion Predictions with MO Diagrams \n"]], ["block_7", ["Give the molecular orbital configuration for the valence electrons in\nWill this ion be stable?\n"]], ["block_8", [" Solution \n"]], ["block_9", ["Looking at the appropriate MO diagram, we see that the \u03c0 orbitals are lower in energy than the \u03c3p orbital. The\nvalence electron configuration for C2 is\nAdding two more electrons to generate the\n"]], ["block_10", ["more bonding electrons than antibonding, the bond order will be 3, and the ion should be stable.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", [{"image_0": "419_0.png", "coords": [90, 57, 522, 380]}]], ["block_13", ["anion will give a valence electron configuration of\nSince this has six\n"]], ["block_14", ["EXAMPLE 8.7\n"]], ["block_15", [" FIGURE 8.40 \nThe molecular orbital energy diagram for O2 predicts two unpaired electrons.\n"]]], "page_420": [["block_0", [" Check Your Learning \n"]], ["block_1", ["How many unpaired electrons would be present on a\nion? Would it be paramagnetic or diamagnetic?\n"]], ["block_2", [" Answer: \ntwo, paramagnetic\n"]], ["block_3", ["Creating molecular orbital diagrams for molecules with more than two atoms relies on the same basic ideas as\nthe diatomic examples presented here. However, with more atoms, computers are required to calculate how\nthe atomic orbitals combine. See three-dimensional drawings (http://openstax.org/l/16orbitaldiag) of the\nmolecular orbitals for C6H6.\n"]], ["block_4", ["LINK TO LEARNING\n"]], ["block_5", [" 8.4 \u2022 Molecular Orbital Theory \n 407 \n"]]], "page_421": [["block_0", [" 408 \n 8 \u2022 Key Terms \n"]], ["block_1", [" Key Terms \n"]], ["block_2", [" antibonding orbital \nmolecular orbital located\n"]], ["block_3", [" bond order \nnumber of pairs of electrons between\n"]], ["block_4", [" bonding orbital \nmolecular orbital located between\n"]], ["block_5", [" degenerate orbitals \norbitals that have the same\n"]], ["block_6", [" diamagnetism \nphenomenon in which a material is\n"]], ["block_7", [" homonuclear diatomic molecule \nmolecule\n"]], ["block_8", [" hybrid orbital orbital created by combining atomic\n"]], ["block_9", [" hybridization model that describes the changes in\n"]], ["block_10", [" linear combination of atomic orbitals technique\n"]], ["block_11", [" molecular orbital region of space in which an\n"]], ["block_12", [" molecular orbital diagram visual representation of\n"]], ["block_13", [" molecular orbital theory model that describes the\n"]], ["block_14", [" node plane separating different lobes of orbitals,\n"]], ["block_15", [" overlap coexistence of orbitals from two different\n"]], ["block_16", [" paramagnetism \nphenomenon in which a material\n"]], ["block_17", [" Key Equations \n"]], ["block_18", [" Access for free at openstax.org \n"]], ["block_19", ["outside of the region between two nuclei;\nelectrons in an antibonding orbital destabilize the\nmolecule\n"]], ["block_20", ["two atoms; it can be found by the number of\nbonds in a Lewis structure or by the difference\nbetween the number of bonding and antibonding\nelectrons divided by two\n"]], ["block_21", ["two nuclei; electrons in a bonding orbital stabilize\na molecule\n"]], ["block_22", ["energy\n"]], ["block_23", ["not magnetic itself but is repelled by a magnetic\nfield; it occurs when there are only paired\nelectrons present\n"]], ["block_24", ["consisting of two identical atoms\n"]], ["block_25", ["orbitals on a central atom\n"]], ["block_26", ["the atomic orbitals of an atom when it forms a\ncovalent compound\n"]], ["block_27", ["for combining atomic orbitals to create molecular\norbitals\n"]], ["block_28", ["electron has a high probability of being found in a\nmolecule\n"]], ["block_29", ["the relative energy levels of molecular orbitals\n"]], ["block_30", ["behavior of electrons delocalized throughout a\nmolecule in terms of the combination of atomic\nwave functions\n"]], ["block_31", ["where the probability of finding an electron is\nzero\n"]], ["block_32", ["atoms sharing the same region of space, leading\nto the formation of a covalent bond\n"]], ["block_33", ["is not magnetic itself but is attracted to a\nmagnetic field; it occurs when there are unpaired\nelectrons present\n"]], ["block_34", [" sp hybrid orbital one of a set of two orbitals with a\n"]], ["block_35", [" sp 2 hybrid orbital one of a set of three orbitals with\n"]], ["block_36", [" sp 3 hybrid orbital one of a set of four orbitals with\n"]], ["block_37", [" sp 3 d hybrid orbital one of a set of five orbitals with\n"]], ["block_38", [" sp 3 d 2 hybrid orbital one of a set of six orbitals with\n"]], ["block_39", [" pi bond (\u03c0 bond) covalent bond formed by side-by-\n"]], ["block_40", [" s-p mixing \nchange that causes \u03c3p orbitals to be\n"]], ["block_41", [" sigma bond ( \u03c3 bond) covalent bond formed by\n"]], ["block_42", [" valence bond theory description of bonding that\n"]], ["block_43", [" \u03c0 bonding orbital molecular orbital formed by\n"]], ["block_44", [" \u03c0* bonding orbital antibonding molecular orbital\n"]], ["block_45", [" \u03c3 bonding orbital molecular orbital in which the\n"]], ["block_46", [" \u03c3 * bonding orbital antibonding molecular orbital\n"]], ["block_47", ["side overlap of atomic orbitals; the electron\ndensity is found on opposite sides of the\ninternuclear axis\n"]], ["block_48", ["less stable than \u03c0p orbitals due to the mixing of s\nand p-based molecular orbitals of similar\nenergies.\n"]], ["block_49", ["overlap of atomic orbitals along the internuclear\naxis\n"]], ["block_50", ["linear arrangement that results from combining\none s and one p orbital\n"]], ["block_51", ["a trigonal planar arrangement that results from\ncombining one s and two p orbitals\n"]], ["block_52", ["a tetrahedral arrangement that results from\ncombining one s and three p orbitals\n"]], ["block_53", ["a trigonal bipyramidal arrangement that results\nfrom combining one s, three p, and one d orbital\n"]], ["block_54", ["an octahedral arrangement that results from\ncombining one s, three p, and two d orbitals\n"]], ["block_55", ["involves atomic orbitals overlapping to form \u03c3 or\n\u03c0 bonds, within which pairs of electrons are\nshared\n"]], ["block_56", ["side-by-side overlap of atomic orbitals, in which\nthe electron density is found on opposite sides of\nthe internuclear axis\n"]], ["block_57", ["formed by out of phase side-by-side overlap of\natomic orbitals, in which the electron density is\nfound on both sides of the internuclear axis, and\nthere is a node between the nuclei\n"]], ["block_58", ["electron density is found along the axis of the\nbond\n"]], ["block_59", ["formed by out-of-phase overlap of atomic orbital\nalong the axis of the bond, generating a node\nbetween the nuclei\n"]]], "page_422": [["block_0", [" Summary \n"]], ["block_1", [" 8.1 Valence Bond Theory \n"]], ["block_2", ["Valence bond theory describes bonding as a\nconsequence of the overlap of two separate atomic\norbitals on different atoms that creates a region with\none pair of electrons shared between the two atoms.\nWhen the orbitals overlap along an axis containing\nthe nuclei, they form a \u03c3 bond. When they overlap in\na fashion that creates a node along this axis, they\nform a \u03c0 bond.\n"]], ["block_3", [" 8.2 Hybrid Atomic Orbitals \n"]], ["block_4", ["We can use hybrid orbitals, which are mathematical\ncombinations of some or all of the valence atomic\norbitals, to describe the electron density around\ncovalently bonded atoms. These hybrid orbitals\neither form sigma (\u03c3) bonds directed toward other\natoms of the molecule or contain lone pairs of\nelectrons. We can determine the type of\nhybridization around a central atom from the\ngeometry of the regions of electron density about it.\nTwo such regions imply sp hybridization; three, sp\n"]], ["block_5", ["hybridization; four, sphybridization; five, spd\nhybridization; and six, spdhybridization. Pi (\u03c0)\nbonds are formed from unhybridized atomic orbitals\n(p or d orbitals).\n"]], ["block_6", [" 8.3 Multiple Bonds \n"]], ["block_7", ["Multiple bonds consist of a \u03c3 bond located along the\naxis between two atoms and one or two \u03c0 bonds. The\n\u03c3 bonds are usually formed by the overlap of\nhybridized atomic orbitals, while the \u03c0 bonds are\nformed by the side-by-side overlap of unhybridized\norbitals. Resonance occurs when there are multiple\nunhybridized orbitals with the appropriate\nalignment to overlap, so the placement of \u03c0 bonds\ncan vary.\n"]], ["block_8", [" Exercises \n"]], ["block_9", [" 8.1 Valence Bond Theory \n"]], ["block_10", [" 1 . Explain how \u03c3 and \u03c0 bonds are similar and how they are different.\n 2 . Draw a curve that describes the energy of a system with H and Cl atoms at varying distances. Then, find\n"]], ["block_11", [" 3 . Explain why bonds occur at specific average bond distances instead of the atoms approaching each other\n"]], ["block_12", ["the minimum energy of this curve two ways.\n(a) Use the bond energy found in Table 8.1 to calculate the energy for one single HCl bond (Hint: How many\nbonds are in a mole?)\n(b) Use the enthalpy of reaction and the bond energies for H2 and Cl2 to solve for the energy of one mole of\nHCl bonds.\n"]], ["block_13", ["infinitely close.\n"]], ["block_14", [" 8.4 Molecular Orbital Theory \n"]], ["block_15", ["Molecular orbital (MO) theory describes the behavior\nof electrons in a molecule in terms of combinations\nof the atomic wave functions. The resulting\nmolecular orbitals may extend over all the atoms in\nthe molecule. Bonding molecular orbitals are\nformed by in-phase combinations of atomic wave\nfunctions, and electrons in these orbitals stabilize a\nmolecule. Antibonding molecular orbitals result\nfrom out-of-phase combinations of atomic wave\nfunctions and electrons in these orbitals make a\nmolecule less stable. Molecular orbitals located\nalong an internuclear axis are called \u03c3 MOs. They\ncan be formed from s orbitals or from p orbitals\noriented in an end-to-end fashion. Molecular\norbitals formed from p orbitals oriented in a side-\nby-side fashion have electron density on opposite\nsides of the internuclear axis and are called \u03c0\norbitals.\n"]], ["block_16", ["We can describe the electronic structure of diatomic\nmolecules by applying molecular orbital theory to\nthe valence electrons of the atoms. Electrons fill\nmolecular orbitals following the same rules that\napply to filling atomic orbitals; Hund\u2019s rule and the\nAufbau principle tell us that lower-energy orbitals\nwill fill first, electrons will spread out before they\npair up, and each orbital can hold a maximum of two\nelectrons with opposite spins. Materials with\nunpaired electrons are paramagnetic and attracted\nto a magnetic field, while those with all-paired\nelectrons are diamagnetic and repelled by a\nmagnetic field. Correctly predicting the magnetic\nproperties of molecules is in advantage of molecular\norbital theory over Lewis structures and valence\nbond theory.\n"]], ["block_17", [" 8 \u2022 Summary \n 409 \n"]]], "page_423": [["block_0", [" 410 \n 8 \u2022 Exercises \n"]], ["block_1", [" 8.2 Hybrid Atomic Orbitals \n"]], ["block_2", [" 9 . Why is the concept of hybridization required in valence bond theory?\n 10 . Give the shape that describes each hybrid orbital set:\n"]], ["block_3", [" 11 . Explain why a carbon atom cannot form five bonds using spd hybrid orbitals.\n 12 . What is the hybridization of the central atom in each of the following?\n"]], ["block_4", [" 13 . A molecule with the formula AB3 could have one of four different shapes. Give the shape and the\n"]], ["block_5", [" 14 . Methionine, CH3SCH2CH2CH(NH2)CO2H, is an amino acid found in proteins. The Lewis structure of this\n"]], ["block_6", [" 15 . Sulfuric acid is manufactured by a series of reactions represented by the following equations:\n"]], ["block_7", [" 16 . Two important industrial chemicals, ethene, C2H4, and propene, C3H6, are produced by the steam (or\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", [" 4 . Use valence bond theory to explain the bonding in F2, HF, and ClBr. Sketch the overlap of the atomic\n"]], ["block_10", [" 5 . Use valence bond theory to explain the bonding in O2. Sketch the overlap of the atomic orbitals involved in\n"]], ["block_11", [" 6 . How many \u03c3 and \u03c0 bonds are present in the molecule HCN?\n 7 . A friend tells you N2 has three \u03c0 bonds due to overlap of the three p-orbitals on each N atom. Do you agree?\n 8 . Draw the Lewis structures for CO2 and CO, and predict the number of \u03c3 and \u03c0 bonds for each molecule.\n"]], ["block_12", ["orbitals involved in the bonds.\n"]], ["block_13", ["the bonds in O2.\n"]], ["block_14", ["(a) CO2\n(b) CO\n"]], ["block_15", ["(a) sp\n"]], ["block_16", ["(b) spd\n(c) sp\n(d) spd\n"]], ["block_17", ["(a) BeH2\n(b) SF6\n(c)\n(d) PCl5\n"]], ["block_18", ["hybridization of the central A atom for each.\n"]], ["block_19", ["compound is shown below. What is the hybridization type of each carbon, oxygen, the nitrogen, and the\nsulfur?\n"]], ["block_20", [{"image_0": "423_0.png", "coords": [91, 418, 271, 494]}]], ["block_21", ["Draw a Lewis structure, predict the molecular geometry by VSEPR, and determine the hybridization of\nsulfur for the following:\n(a) circular S8 molecule\n(b) SO2 molecule\n(c) SO3 molecule\n(d) H2SO4 molecule (the hydrogen atoms are bonded to oxygen atoms)\n"]], ["block_22", ["thermal) cracking process:\n"]], ["block_23", ["For each of the four carbon compounds, do the following:\n(a) Draw a Lewis structure.\n(b) Predict the geometry about the carbon atom.\n(c) Determine the hybridization of each type of carbon atom.\n"]]], "page_424": [["block_0", [" 17 . Analysis of a compound indicates that it contains 77.55% Xe and 22.45% F by mass.\n"]], ["block_1", [" 18 . Consider nitrous acid, HNO2 (HONO).\n"]], ["block_2", [" 19 . Strike-anywhere matches contain a layer of KClO3 and a layer of P4S3. The heat produced by the friction of\n"]], ["block_3", [" 20 . Identify the hybridization of each carbon atom in the following molecule. (The arrangement of atoms is\n"]], ["block_4", [" 21 . Write Lewis structures for NF3 and PF5. On the basis of hybrid orbitals, explain the fact that NF3, PF3, and\n"]], ["block_5", [" 22 . In addition to NF3, two other fluoro derivatives of nitrogen are known: N2F4 and N2F2. What shapes do you\n"]], ["block_6", [" 8.3 Multiple Bonds \n"]], ["block_7", [" 23 . The bond energy of a C\u2013C single bond averages 347 kJ mol; that of a\ntriple bond averages 839 kJ\n"]], ["block_8", [" 24 . For the carbonate ion,\ndraw all of the resonance structures. Identify which orbitals overlap to\n"]], ["block_9", [" 25 . A useful solvent that will dissolve salts as well as organic compounds is the compound acetonitrile,\n"]], ["block_10", [" 26 . For the molecule allene,\ngive the hybridization of each carbon atom. Will the hydrogen\n"]], ["block_11", ["(a) What is the empirical formula for this compound? (Assume this is also the molecular formula in\nresponding to the remaining parts of this exercise).\n(b) Write a Lewis structure for the compound.\n(c) Predict the shape of the molecules of the compound.\n(d) What hybridization is consistent with the shape you predicted?\n"]], ["block_12", ["(a) Write a Lewis structure.\n(b) What are the electron pair and molecular geometries of the internal oxygen and nitrogen atoms in the\nHNO2 molecule?\n(c) What is the hybridization on the internal oxygen and nitrogen atoms in HNO2?\n"]], ["block_13", ["striking the match causes these two compounds to react vigorously, which sets fire to the wooden stem of\nthe match. KClO3 contains the\nion. P4S3 is an unusual molecule with the skeletal structure.\n"]], ["block_14", [{"image_0": "424_0.png", "coords": [91, 234, 208, 299]}]], ["block_15", ["(a) Write Lewis structures for P4S3 and the\nion.\n"]], ["block_16", ["(b) Describe the geometry about the P atoms, the S atom, and the Cl atom in these species.\n(c) Assign a hybridization to the P atoms, the S atom, and the Cl atom in these species.\n(d) Determine the oxidation states and formal charge of the atoms in P4S3 and the\nion.\n"]], ["block_17", ["given; you need to determine how many bonds connect each pair of atoms.)\n"]], ["block_18", [{"image_1": "424_1.png", "coords": [91, 377, 325, 429]}]], ["block_19", ["PF5 are stable molecules, but NF5 does not exist.\n"]], ["block_20", ["predict for these two molecules? What is the hybridization for the nitrogen in each molecule?\n"]], ["block_21", ["mol. Explain why the triple bond is not three times as strong as a single bond.\n"]], ["block_22", ["create each bond.\n"]], ["block_23", ["H3CCN. It is present in paint strippers.\n(a) Write the Lewis structure for acetonitrile, and indicate the direction of the dipole moment in the\nmolecule.\n(b) Identify the hybrid orbitals used by the carbon atoms in the molecule to form \u03c3 bonds.\n(c) Describe the atomic orbitals that form the \u03c0 bonds in the molecule. Note that it is not necessary to\nhybridize the nitrogen atom.\n"]], ["block_24", ["atoms be in the same plane or perpendicular planes?\n"]], ["block_25", [" 8 \u2022 Exercises \n 411 \n"]]], "page_425": [["block_0", [" 412 \n 8 \u2022 Exercises \n"]], ["block_1", [" 27 . Identify the hybridization of the central atom in each of the following molecules and ions that contain\n"]], ["block_2", [" 28 . Describe the molecular geometry and hybridization of the N, P, or S atoms in each of the following\n"]], ["block_3", [" 29 . For each of the following molecules, indicate the hybridization requested and whether or not the electrons\n"]], ["block_4", [" 30 . For each of the following structures, determine the hybridization requested and whether the electrons will\n"]], ["block_5", [" 31 . Draw the orbital diagram for carbon in CO2 showing how many carbon atom electrons are in each orbital.\n"]], ["block_6", [" 8.4 Molecular Orbital Theory \n"]], ["block_7", [" 32 . Sketch the distribution of electron density in the bonding and antibonding molecular orbitals formed\n"]], ["block_8", [" 33 . How are the following similar, and how do they differ?\n"]], ["block_9", [" 34 . If molecular orbitals are created by combining five atomic orbitals from atom A and five atomic orbitals\n"]], ["block_10", [" 35 . Can a molecule with an odd number of electrons ever be diamagnetic? Explain why or why not.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["multiple bonds:\n(a) ClNO (N is the central atom)\n(b) CS2\n(c) Cl2CO (C is the central atom)\n(d) Cl2SO (S is the central atom)\n(e) SO2F2 (S is the central atom)\n(f) XeO2F2 (Xe is the central atom)\n(g)\n(Cl is the central atom)\n"]], ["block_13", ["compounds.\n(a) H3PO4, phosphoric acid, used in cola soft drinks\n(b) NH4NO3, ammonium nitrate, a fertilizer and explosive\n(c) S2Cl2, disulfur dichloride, used in vulcanizing rubber\n(d) K4[O3POPO3], potassium pyrophosphate, an ingredient in some toothpastes\n"]], ["block_14", ["will be delocalized:\n(a) ozone (O3) central O hybridization\n(b) carbon dioxide (CO2) central C hybridization\n(c) nitrogen dioxide (NO2) central N hybridization\n(d) phosphate ion\ncentral P hybridization\n"]], ["block_15", ["be delocalized:\n(a) Hybridization of each carbon\n"]], ["block_16", [{"image_0": "425_0.png", "coords": [91, 360, 208, 412]}]], ["block_17", ["(b) Hybridization of sulfur\n"]], ["block_18", [{"image_1": "425_1.png", "coords": [91, 427, 208, 462]}]], ["block_19", ["(c) All atoms\n"]], ["block_20", [{"image_2": "425_2.png", "coords": [91, 477, 208, 570]}]], ["block_21", ["from two s orbitals and from two p orbitals.\n"]], ["block_22", ["(a) \u03c3 molecular orbitals and \u03c0 molecular orbitals\n(b) \u03c8 for an atomic orbital and \u03c8 for a molecular orbital\n(c) bonding orbitals and antibonding orbitals\n"]], ["block_23", ["from atom B combine, how many molecular orbitals will result?\n"]]], "page_426": [["block_0", [" 36 . Can a molecule with an even number of electrons ever be paramagnetic? Explain why or why not.\n 37 . Why are bonding molecular orbitals lower in energy than the parent atomic orbitals?\n 38 . Calculate the bond order for an ion with this configuration:\n"]], ["block_1", [" 39 . Explain why an electron in the bonding molecular orbital in the H2 molecule has a lower energy than an\n"]], ["block_2", [" 40 . Predict the valence electron molecular orbital configurations for the following, and state whether they will\n"]], ["block_3", [" 41 . Determine the bond order of each member of the following groups, and determine which member of each\n"]], ["block_4", [" 42 . For the first ionization energy for an N2 molecule, what molecular orbital is the electron removed from?\n 43 . Compare the atomic and molecular orbital diagrams to identify the member of each of the following pairs\n"]], ["block_5", [" 44 . Which of the period 2 homonuclear diatomic molecules are predicted to be paramagnetic?\n 45 . A friend tells you that the 2s orbital for fluorine starts off at a much lower energy than the 2s orbital for\n"]], ["block_6", [" 46 . True or false: Boron contains 2s2pvalence electrons, so only one p orbital is needed to form molecular\n"]], ["block_7", [" 47 . What charge would be needed on F2 to generate an ion with a bond order of 2?\n 48 . Predict whether the MO diagram for S2 would show s-p mixing or not.\n 49 . Explain why\nis diamagnetic, while\nwhich has the same number of valence electrons, is\n"]], ["block_8", [" 50 . Using the MO diagrams, predict the bond order for the stronger bond in each pair:\n"]], ["block_9", ["electron in the 1s atomic orbital of either of the separated hydrogen atoms.\n"]], ["block_10", ["be stable or unstable ions.\n(a)\n(b)\n"]], ["block_11", ["(c)\n(d)\n(e)\n(f)\n(g)\n(h)\n"]], ["block_12", ["group is predicted by the molecular orbital model to have the strongest bond.\n(a) H2,\n(b) O2,\n(c) Li2,\nBe2\n"]], ["block_13", ["(d) F2,\n(e) N2,\n"]], ["block_14", ["that has the highest first ionization energy (the most tightly bound electron) in the gas phase:\n(a) H and H2\n(b) N and N2\n(c) O and O2\n(d) C and C2\n(e) B and B2\n"]], ["block_15", ["lithium, so the resulting \u03c32s molecular orbital in F2 is more stable than in Li2. Do you agree?\n"]], ["block_16", ["orbitals.\n"]], ["block_17", ["paramagnetic.\n"]], ["block_18", ["(a) B2 or\n(b) F2 or\n(c) O2 or\n(d)\nor\n"]], ["block_19", [" 8 \u2022 Exercises \n 413 \n"]]], "page_427": [["block_0", [" 414 \n 8 \u2022 Exercises \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_428": [["block_0", ["CHAPTER 9\nGases\n"]], ["block_1", [{"image_0": "428_0.png", "coords": [72, 104, 622, 358]}]], ["block_2", [" Figure 9.1 \nThe hot air inside these balloons is less dense than the surrounding cool air. This results in a buoyant\n"]], ["block_3", ["force that causes the balloons to rise when their guy lines are untied. (credit: modification of work by Anthony\nQuintano)\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 9.1 Gas Pressure \n 9.2 Relating Pressure, Volume, Amount, and Temperature: The Ideal Gas Law \n 9.3 Stoichiometry of Gaseous Substances, Mixtures, and Reactions \n 9.4 Effusion and Diffusion of Gases \n 9.5 The Kinetic-Molecular Theory \n 9.6 Non-Ideal Gas Behavior \n"]], ["block_6", [" INTRODUCTION \n"]], ["block_7", ["gases are familiar to us from our daily activities. Heated gases expand, which can make a hot air balloon rise\n(Figure 9.1) or cause a blowout in a bicycle tire left in the sun on a hot day.\n"]], ["block_8", ["Gases have played an important part in the development of chemistry. In the seventeenth and eighteenth\ncenturies, many scientists investigated gas behavior, providing the first mathematical descriptions of the\nbehavior of matter.\n"]], ["block_9", ["In this chapter, we will examine the relationships between gas temperature, pressure, amount, and volume. We\nwill study a simple theoretical model and use it to analyze the experimental behavior of gases. The results of\nthese analyses will show us the limitations of the theory and how to improve on it.\n"]], ["block_10", ["We are surrounded by an ocean of gas\u2014the atmosphere\u2014and many of the properties of\n"]]], "page_429": [["block_0", [" 416 \n 9 \u2022 Gases \n"]], ["block_1", [" 9.1 Gas Pressure \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["The earth\u2019s atmosphere exerts a pressure, as does any other gas. Although we do not normally notice\natmospheric pressure, we are sensitive to pressure changes\u2014for example, when your ears \u201cpop\u201d during take-\noff and landing while flying, or when you dive underwater. Gas pressure is caused by the force exerted by gas\nmolecules colliding with the surfaces of objects (Figure 9.2). Although the force of each collision is very small,\nany surface of appreciable area experiences a large number of collisions in a short time, which can result in a\nhigh pressure. In fact, normal air pressure is strong enough to crush a metal container when not balanced by\nequal pressure from inside the container.\n"]], ["block_4", [" FIGURE 9.2 \nThe atmosphere above us exerts a large pressure on objects at the surface of the earth, roughly equal\n"]], ["block_5", ["to the weight of a bowling ball pressing on an area the size of a human thumbnail.\n"]], ["block_6", ["A dramatic illustration (http://openstax.org/l/16atmospressur1) of atmospheric pressure is provided in this\nbrief video, which shows a railway tanker car imploding when its internal pressure is decreased.\n"]], ["block_7", ["A smaller scale demonstration (http://openstax.org/l/16atmospressur2) of this phenomenon is briefly\nexplained.\n"]], ["block_8", ["Atmospheric pressure is caused by the weight of the column of air molecules in the atmosphere above an\nobject, such as the tanker car. At sea level, this pressure is roughly the same as that exerted by a full-grown\nAfrican elephant standing on a doormat, or a typical bowling ball resting on your thumbnail. These may seem\nlike huge amounts, and they are, but life on earth has evolved under such atmospheric pressure. If you actually\nperch a bowling ball on your thumbnail, the pressure experienced is twice the usual pressure, and the\nsensation is unpleasant.\n"]], ["block_9", ["In general, pressure is defined as the force exerted on a given area:\nNote that pressure is directly\n"]], ["block_10", ["proportional to force and inversely proportional to area. Thus, pressure can be increased either by increasing\nthe amount of force or by decreasing the area over which it is applied; pressure can be decreased by\ndecreasing the force or increasing the area.\n"]], ["block_11", ["Let\u2019s apply this concept to determine which exerts a greater pressure in Figure 9.3\u2014the elephant or the figure\nskater? A large African elephant can weigh 7 tons, supported on four feet, each with a diameter of about 1.5 ft\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["\u2022\nDefine the property of pressure\n"]], ["block_14", ["\u2022\nDefine and convert among the units of pressure measurements\n"]], ["block_15", ["\u2022\nDescribe the operation of common tools for measuring gas pressure\n"]], ["block_16", ["\u2022\nCalculate pressure from manometer data\n"]], ["block_17", ["LINK TO LEARNING\n"]], ["block_18", [{"image_0": "429_0.png", "coords": [130, 259, 481, 424]}]]], "page_430": [["block_0", ["(footprint area of 250 in), so the pressure exerted by each foot is about 14 lb/in:\n"]], ["block_1", ["The figure skater weighs about 120 lbs, supported on two skate blades, each with an area of about 2 in, so the\npressure exerted by each blade is about 30 lb/in:\n"]], ["block_2", ["Even though the elephant is more than one hundred-times heavier than the skater, it exerts less than one-half\nof the pressure. On the other hand, if the skater removes their skates and stands with bare feet (or regular\nfootwear) on the ice, the larger area over which their weight is applied greatly reduces the pressure exerted:\n"]], ["block_3", [" FIGURE 9.3 \nAlthough (a) an elephant\u2019s weight is large, creating a very large force on the ground, (b) the figure\n"]], ["block_4", ["skater exerts a much higher pressure on the ice due to the small surface area of the skates. (credit a: modification of\nwork by Guido da Rozze; credit b: modification of work by Ryosuke Yagi)\n"]], ["block_5", ["The SI unit of pressure is the pascal (Pa) , with 1 Pa = 1 N/m, where N is the newton, a unit of force defined as 1\nkg m/s. One pascal is a small pressure; in many cases, it is more convenient to use units of kilopascal (1 kPa =\n1000 Pa) or bar (1 bar = 100,000 Pa). In the United States, pressure is often measured in pounds of force on an\narea of one square inch\u2014 pounds per square inch (psi) \u2014for example, in car tires. Pressure can also be\nmeasured using the unit atmosphere (atm) , which originally represented the average sea level air pressure at\nthe approximate latitude of Paris (45\u00b0). Table 9.1 provides some information on these and a few other common\nunits for pressure measurements\n"]], ["block_6", [" TABLE 9.1 \n"]], ["block_7", [" Unit Name and Abbreviation \n Definition or Relation to Other Unit \n"]], ["block_8", ["pascal (Pa)\n1 Pa = 1 N/m\n"]], ["block_9", ["kilopascal (kPa)\n1 kPa = 1000 Pa\n"]], ["block_10", ["pounds per square inch (psi)\nair pressure at sea level is ~14.7 psi\n"]], ["block_11", ["atmosphere (atm)\n1 atm = 101,325 Pa = 760 torr\nair pressure at sea level is ~1 atm\n"]], ["block_12", [{"image_0": "430_0.png", "coords": [130, 243, 481, 379]}]], ["block_13", ["recommended IUPAC unit\n"]], ["block_14", ["Pressure Units\n"]], ["block_15", [" 9.1 \u2022 Gas Pressure \n 417 \n"]]], "page_431": [["block_0", [" 418 \n 9 \u2022 Gases \n"]], ["block_1", [" Conversion of Pressure Units \n"]], ["block_2", ["The United States National Weather Service reports pressure in both inches of Hg and millibars. Convert a\npressure of 29.2 in. Hg into:\n"]], ["block_3", ["(a) torr\n"]], ["block_4", ["(b) atm\n"]], ["block_5", ["(c) kPa\n"]], ["block_6", ["(d) mbar\n"]], ["block_7", [" Solution \n"]], ["block_8", ["This is a unit conversion problem. The relationships between the various pressure units are given in Table 9.1.\n"]], ["block_9", ["(a)\n"]], ["block_10", ["(b)\n"]], ["block_11", ["(c)\n"]], ["block_12", ["(d)\n"]], ["block_13", [" Check Your Learning \n"]], ["block_14", ["A typical barometric pressure in Kansas City is 740 torr. What is this pressure in atmospheres, in millimeters\nof mercury, in kilopascals, and in bar?\n"]], ["block_15", [" Answer: \n0.974 atm; 740 mm Hg; 98.7 kPa; 0.987 bar\n"]], ["block_16", ["We can measure atmospheric pressure, the force exerted by the atmosphere on the earth\u2019s surface, with a\n barometer (Figure 9.4). A barometer is a glass tube that is closed at one end, filled with a nonvolatile liquid\nsuch as mercury, and then inverted and immersed in a container of that liquid. The atmosphere exerts\npressure on the liquid outside the tube, the column of liquid exerts pressure inside the tube, and the pressure\nat the liquid surface is the same inside and outside the tube. The height of the liquid in the tube is therefore\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", [" TABLE 9.1 \n"]], ["block_19", ["EXAMPLE 9.1\n"]], ["block_20", [" Unit Name and Abbreviation \n Definition or Relation to Other Unit \n"]], ["block_21", ["bar (bar, or b)\n1 bar = 100,000 Pa (exactly)\ncommonly used in meteorology\n"]], ["block_22", ["millibar (mbar, or mb)\n1000 mbar = 1 bar\n"]], ["block_23", ["inches of mercury (in. Hg)\n1 in. Hg = 3386 Pa\nused by aviation industry, also some weather reports\n"]], ["block_24", ["torr\n"]], ["block_25", ["millimeters of mercury (mm Hg)\n1 mm Hg ~1 torr\n"]], ["block_26", ["named after Evangelista Torricelli, inventor of the barometer\n"]]], "page_432": [["block_0", ["proportional to the pressure exerted by the atmosphere.\n"]], ["block_1", [" FIGURE 9.4 \nIn a barometer, the height, h, of the column of liquid is used as a measurement of the air pressure.\n"]], ["block_2", ["Using very dense liquid mercury (left) permits the construction of reasonably sized barometers, whereas using\nwater (right) would require a barometer more than 30 feet tall.\n"]], ["block_3", ["If the liquid is water, normal atmospheric pressure will support a column of water over 10 meters high, which\nis rather inconvenient for making (and reading) a barometer. Because mercury (Hg) is about 13.6-times denser\nthan water, a mercury barometer only needs to be\nas tall as a water barometer\u2014a more suitable size.\n"]], ["block_4", ["Standard atmospheric pressure of 1 atm at sea level (101,325 Pa) corresponds to a column of mercury that is\nabout 760 mm (29.92 in.) high. The torr was originally intended to be a unit equal to one millimeter of\nmercury, but it no longer corresponds exactly. The pressure exerted by a fluid due to gravity is known as\n hydrostatic pressure , p:\n"]], ["block_5", ["where h is the height of the fluid, \u03c1 is the density of the fluid, and g is acceleration due to gravity.\n"]], ["block_6", [" Calculation of Barometric Pressure \n"]], ["block_7", ["Show the calculation supporting the claim that atmospheric pressure near sea level corresponds to the\npressure exerted by a column of mercury that is about 760 mm high. The density of mercury = 13.6 g/cm.\n"]], ["block_8", [" Solution \n"]], ["block_9", ["The hydrostatic pressure is given by p = h\u03c1g, with h = 760 mm, \u03c1 = 13.6 g/cm, and g = 9.81 m/s. Plugging\nthese values into the equation and doing the necessary unit conversions will give us the value we seek. (Note:\nWe are expecting to find a pressure of ~101,325 Pa.)\n"]], ["block_10", ["EXAMPLE 9.2\n"]], ["block_11", [{"image_0": "432_0.png", "coords": [189, 76, 423, 309]}]], ["block_12", [" 9.1 \u2022 Gas Pressure \n 419 \n"]]], "page_433": [["block_0", [" 420 \n 9 \u2022 Gases \n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["Calculate the height of a column of water at 25 \u00b0C that corresponds to normal atmospheric pressure. The\ndensity of water at this temperature is 1.0 g/cm.\n"]], ["block_3", [" Answer: \n10.3 m\n"]], ["block_4", ["A manometer is a device similar to a barometer that can be used to measure the pressure of a gas trapped in a\ncontainer. A closed-end manometer is a U-shaped tube with one closed arm, one arm that connects to the gas\nto be measured, and a nonvolatile liquid (usually mercury) in between. As with a barometer, the distance\nbetween the liquid levels in the two arms of the tube (h in the diagram) is proportional to the pressure of the\ngas in the container. An open-end manometer (Figure 9.5) is the same as a closed-end manometer, but one of\nits arms is open to the atmosphere. In this case, the distance between the liquid levels corresponds to the\ndifference in pressure between the gas in the container and the atmosphere.\n"]], ["block_5", [" FIGURE 9.5 \nA manometer can be used to measure the pressure of a gas. The (difference in) height between the\n"]], ["block_6", ["liquid levels (h) is a measure of the pressure. Mercury is usually used because of its large density.\n"]], ["block_7", [" Calculation of Pressure Using a Closed-End Manometer \n"]], ["block_8", ["The pressure of a sample of gas is measured with a closed-end manometer, as shown to the right. The liquid in\nthe manometer is mercury. Determine the pressure of the gas in:\n"]], ["block_9", ["(a) torr\n"]], ["block_10", ["(b) Pa\n"]], ["block_11", ["(c) bar\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", [{"image_0": "433_0.png", "coords": [82, 264, 529, 425]}]], ["block_14", ["EXAMPLE 9.3\n"]]], "page_434": [["block_0", [{"image_0": "434_0.png", "coords": [72, 57, 432, 199]}]], ["block_1", [" Solution \n"]], ["block_2", ["The pressure of the gas is equal to a column of mercury of height 26.4 cm. (The pressure at the bottom\nhorizontal line is equal on both sides of the tube. The pressure on the left is due to the gas and the pressure on\nthe right is due to 26.4 cm Hg, or mercury.) We could use the equation p = h\u03c1g as in Example 9.2, but it is\nsimpler to just convert between units using Table 9.1.\n"]], ["block_3", ["(a)\n"]], ["block_4", ["(b)\n"]], ["block_5", ["(c)\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["The pressure of a sample of gas is measured with a closed-end manometer. The liquid in the manometer is\nmercury. Determine the pressure of the gas in:\n"]], ["block_8", ["(a) torr\n"]], ["block_9", ["(b) Pa\n"]], ["block_10", ["(c) bar\n"]], ["block_11", [{"image_1": "434_1.png", "coords": [72, 448, 432, 589]}]], ["block_12", [" Answer: \n(a) ~150 torr; (b) ~20,000 Pa; (c) ~0.20 bar\n"]], ["block_13", [" Calculation of Pressure Using an Open-End Manometer \n"]], ["block_14", ["The pressure of a sample of gas is measured at sea level with an open-end Hg (mercury) manometer, as shown\nto the right. Determine the pressure of the gas in:\n"]], ["block_15", ["EXAMPLE 9.4\n"]], ["block_16", [" 9.1 \u2022 Gas Pressure \n 421 \n"]]], "page_435": [["block_0", [" 422 \n 9 \u2022 Gases \n"]], ["block_1", ["(a) mm Hg\n"]], ["block_2", ["(b) atm\n"]], ["block_3", ["(c) kPa\n"]], ["block_4", [{"image_0": "435_0.png", "coords": [72, 114, 432, 255]}]], ["block_5", [" Solution \n"]], ["block_6", ["The pressure of the gas equals the hydrostatic pressure due to a column of mercury of height 13.7 cm plus the\npressure of the atmosphere at sea level. (The pressure at the bottom horizontal line is equal on both sides of\nthe tube. The pressure on the left is due to the gas and the pressure on the right is due to 13.7 cm of Hg plus\natmospheric pressure.)\n"]], ["block_7", ["(a) In mm Hg, this is: 137 mm Hg + 760 mm Hg = 897 mm Hg\n"]], ["block_8", ["(b)\n"]], ["block_9", ["(c)\n"]], ["block_10", [" Check Your Learning \n"]], ["block_11", ["The pressure of a sample of gas is measured at sea level with an open-end Hg manometer, as shown to the\nright. Determine the pressure of the gas in:\n"]], ["block_12", ["(a) mm Hg\n"]], ["block_13", ["(b) atm\n"]], ["block_14", ["(c) kPa\n"]], ["block_15", [{"image_1": "435_1.png", "coords": [72, 498, 432, 639]}]], ["block_16", [" Answer: \n(a) 642 mm Hg; (b) 0.845 atm; (c) 85.6 kPa\n"]], ["block_17", [" Access for free at openstax.org \n"]]], "page_436": [["block_0", [" Meteorology, Climatology, and Atmospheric Science \nThroughout the ages, people have observed clouds, winds, and precipitation, trying to discern patterns and\nmake predictions: when it is best to plant and harvest; whether it is safe to set out on a sea voyage; and much\nmore. We now face complex weather and atmosphere-related challenges that will have a major impact on our\ncivilization and the ecosystem. Several different scientific disciplines use chemical principles to help us better\nunderstand weather, the atmosphere, and climate. These are meteorology, climatology, and atmospheric\nscience. Meteorology is the study of the atmosphere, atmospheric phenomena, and atmospheric effects on\nearth\u2019s weather. Meteorologists seek to understand and predict the weather in the short term, which can save\nlives and benefit the economy. Weather forecasts (Figure 9.7) are the result of thousands of measurements of\nair pressure, temperature, and the like, which are compiled, modeled, and analyzed in weather centers\nworldwide.\n"]], ["block_1", [" Measuring Blood Pressure \nBlood pressure is measured using a device called a sphygmomanometer (Greek sphygmos = \u201cpulse\u201d). It\nconsists of an inflatable cuff to restrict blood flow, a manometer to measure the pressure, and a method of\ndetermining when blood flow begins and when it becomes impeded (Figure 9.6). Since its invention in\n1881, it has been an essential medical device. There are many types of sphygmomanometers: manual ones\nthat require a stethoscope and are used by medical professionals; mercury ones, used when the most\naccuracy is required; less accurate mechanical ones; and digital ones that can be used with little training\nbut that have limitations. When using a sphygmomanometer, the cuff is placed around the upper arm and\ninflated until blood flow is completely blocked, then slowly released. As the heart beats, blood forced\nthrough the arteries causes a rise in pressure. This rise in pressure at which blood flow begins is the\nsystolic pressure\u2014the peak pressure in the cardiac cycle. When the cuff\u2019s pressure equals the arterial\nsystolic pressure, blood flows past the cuff, creating audible sounds that can be heard using a stethoscope.\nThis is followed by a decrease in pressure as the heart\u2019s ventricles prepare for another beat. As cuff\npressure continues to decrease, eventually sound is no longer heard; this is the diastolic pressure\u2014the\nlowest pressure (resting phase) in the cardiac cycle. Blood pressure units from a sphygmomanometer are\nin terms of millimeters of mercury (mm Hg).\n"]], ["block_2", ["Chemistry in Everyday Life\n"]], ["block_3", [" FIGURE 9.6 \n(a) A medical technician prepares to measure a patient\u2019s blood pressure with a\n"]], ["block_4", ["sphygmomanometer. (b) A typical sphygmomanometer uses a valved rubber bulb to inflate the cuff and a\ndiaphragm gauge to measure pressure. (credit a: modification of work by Master Sgt. Jeffrey Allen)\n"]], ["block_5", ["HOW SCIENCES INTERCONNECT\n"]], ["block_6", [{"image_0": "436_0.png", "coords": [130, 294, 481, 406]}]], ["block_7", [" 9.1 \u2022 Gas Pressure \n 423 \n"]]], "page_437": [["block_0", [" 424 \n 9 \u2022 Gases \n"]], ["block_1", [" FIGURE 9.7 \nMeteorologists use weather maps to describe and predict weather. Regions of high (H) and low (L)\n"]], ["block_2", ["pressure have large effects on weather conditions. The gray lines represent locations of constant pressure known as\nisobars. (credit: modification of work by National Oceanic and Atmospheric Administration)\n"]], ["block_3", ["In terms of weather, low-pressure systems occur when the earth\u2019s surface atmospheric pressure is lower than\nthe surrounding environment: Moist air rises and condenses, producing clouds. Movement of moisture and air\nwithin various weather fronts instigates most weather events.\n"]], ["block_4", ["The atmosphere is the gaseous layer that surrounds a planet. Earth\u2019s atmosphere, which is roughly 100\u2013125\nkm thick, consists of roughly 78.1% nitrogen and 21.0% oxygen, and can be subdivided further into the\nregions shown in Figure 9.8: the exosphere (furthest from earth, > 700 km above sea level), the thermosphere\n(80\u2013700 km), the mesosphere (50\u201380 km), the stratosphere (second lowest level of our atmosphere, 12\u201350 km\nabove sea level), and the troposphere (up to 12 km above sea level, roughly 80% of the earth\u2019s atmosphere by\nmass and the layer where most weather events originate). As you go higher in the troposphere, air density and\ntemperature both decrease.\n"]], ["block_5", [" FIGURE 9.8 \nEarth\u2019s atmosphere has five layers: the troposphere, the stratosphere, the mesosphere, the\n"]], ["block_6", ["thermosphere, and the exosphere.\n"]], ["block_7", ["Climatology is the study of the climate, averaged weather conditions over long time periods, using atmospheric\ndata. However, climatologists study patterns and effects that occur over decades, centuries, and millennia,\nrather than shorter time frames of hours, days, and weeks like meteorologists. Atmospheric science is an even\nbroader field, combining meteorology, climatology, and other scientific disciplines that study the atmosphere.\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", [{"image_0": "437_0.png", "coords": [90, 387, 522, 584]}]], ["block_10", [{"image_1": "437_1.png", "coords": [189, 57, 423, 202]}]]], "page_438": [["block_0", ["During the seventeenth and especially eighteenth centuries, driven both by a desire to understand nature and\na quest to make balloons in which they could fly (Figure 9.9), a number of scientists established the\nrelationships between the macroscopic physical properties of gases, that is, pressure, volume, temperature,\nand amount of gas. Although their measurements were not precise by today\u2019s standards, they were able to\ndetermine the mathematical relationships between pairs of these variables (e.g., pressure and temperature,\npressure and volume) that hold for an ideal gas\u2014a hypothetical construct that real gases approximate under\ncertain conditions. Eventually, these individual laws were combined into a single equation\u2014the ideal gas\nlaw\u2014that relates gas quantities for gases and is quite accurate for low pressures and moderate temperatures.\nWe will consider the key developments in individual relationships (for pedagogical reasons not quite in\nhistorical order), then put them together in the ideal gas law.\n"]], ["block_1", [" 9.2 Relating Pressure, Volume, Amount, and Temperature: The Ideal Gas Law \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", [{"image_0": "438_0.png", "coords": [72, 283, 540, 411]}]], ["block_4", [" FIGURE 9.9 \nIn 1783, the first (a) hydrogen-filled balloon flight, (b) manned hot air balloon flight, and (c) manned\n"]], ["block_5", ["hydrogen-filled balloon flight occurred. When the hydrogen-filled balloon depicted in (a) landed, the frightened\nvillagers of Gonesse reportedly destroyed it with pitchforks and knives. The launch of the latter was reportedly\nviewed by 400,000 people in Paris.\n"]], ["block_6", [" Pressure and Temperature: Amontons\u2019s Law \n"]], ["block_7", ["Imagine filling a rigid container attached to a pressure gauge with gas and then sealing the container so that no\ngas may escape. If the container is cooled, the gas inside likewise gets colder and its pressure is observed to\ndecrease. Since the container is rigid and tightly sealed, both the volume and number of moles of gas remain\nconstant. If we heat the sphere, the gas inside gets hotter (Figure 9.10) and the pressure increases.\n"]], ["block_8", ["\u2022\nIdentify the mathematical relationships between the various properties of gases\n"]], ["block_9", ["\u2022\nUse the ideal gas law, and related gas laws, to compute the values of various gas properties under specified\nconditions\n"]], ["block_10", [" 9.2 \u2022 Relating Pressure, Volume, Amount, and Temperature: The Ideal Gas Law \n 425 \n"]]], "page_439": [["block_0", [" 426 \n 9 \u2022 Gases \n"]], ["block_1", ["This relationship between temperature and pressure is observed for any sample of gas confined to a constant\nvolume. An example of experimental pressure-temperature data is shown for a sample of air under these\nconditions in Figure 9.11. We find that temperature and pressure are linearly related, and if the temperature is\non the kelvin scale, then P and T are directly proportional (again, when volume and moles of gas are held\nconstant); if the temperature on the kelvin scale increases by a certain factor, the gas pressure increases by the\nsame factor.\n"]], ["block_2", ["Guillaume Amontons was the first to empirically establish the relationship between the pressure and the\ntemperature of a gas (~1700), and Joseph Louis Gay-Lussac determined the relationship more precisely\n(~1800). Because of this, the P-T relationship for gases is known as either Amontons\u2019s law or Gay-Lussac\u2019s \n law . Under either name, it states that the pressure of a given amount of gas is directly proportional to its\ntemperature on the kelvin scale when the volume is held constant. Mathematically, this can be written:\n"]], ["block_3", [{"image_0": "439_0.png", "coords": [72, 57, 540, 281]}]], ["block_4", [" FIGURE 9.10 \nThe effect of temperature on gas pressure: When the hot plate is off, the pressure of the gas in the\n"]], ["block_5", ["sphere is relatively low. As the gas is heated, the pressure of the gas in the sphere increases.\n"]], ["block_6", [{"image_1": "439_1.png", "coords": [72, 397, 540, 548]}]], ["block_7", [" FIGURE 9.11 \nFor a constant volume and amount of air, the pressure and temperature are directly proportional,\n"]], ["block_8", ["provided the temperature is in kelvin. (Measurements cannot be made at lower temperatures because of the\ncondensation of the gas.) When this line is extrapolated to lower pressures, it reaches a pressure of 0 at \u2013273 \u00b0C,\nwhich is 0 on the kelvin scale and the lowest possible temperature, called absolute zero.\n"]], ["block_9", ["where \u221d means \u201cis proportional to,\u201d and k is a proportionality constant that depends on the identity, amount,\nand volume of the gas.\n"]], ["block_10", [" Access for free at openstax.org \n"]]], "page_440": [["block_0", ["For a confined, constant volume of gas, the ratio\nis therefore constant (i.e.,\n). If the gas is initially in\n"]], ["block_1", ["\u201cCondition 1\u201d (with P = P1 and T = T1), and then changes to \u201cCondition 2\u201d (with P = P2 and T = T2), we have that\n"]], ["block_2", ["calculations for a confined gas at constant volume. Note that temperatures must be on the kelvin scale for any\ngas law calculations (0 on the kelvin scale and the lowest possible temperature is called absolute zero ). (Also\nnote that there are at least three ways we can describe how the pressure of a gas changes as its temperature\nchanges: We can use a table of values, a graph, or a mathematical equation.)\n"]], ["block_3", [" Predicting Change in Pressure with Temperature \n"]], ["block_4", ["A can of hair spray is used until it is empty except for the propellant, isobutane gas.\n"]], ["block_5", ["(a) On the can is the warning \u201cStore only at temperatures below 120 \u00b0F (48.8 \u00b0C). Do not incinerate.\u201d Why?\n"]], ["block_6", ["(b) The gas in the can is initially at 24 \u00b0C and 360 kPa, and the can has a volume of 350 mL. If the can is left in a\ncar that reaches 50 \u00b0C on a hot day, what is the new pressure in the can?\n"]], ["block_7", [" Solution \n"]], ["block_8", ["(a) The can contains an amount of isobutane gas at a constant volume, so if the temperature is increased by\nheating, the pressure will increase proportionately. High temperature could lead to high pressure, causing the\ncan to burst. (Also, isobutane is combustible, so incineration could cause the can to explode.)\n"]], ["block_9", ["(b) We are looking for a pressure change due to a temperature change at constant volume, so we will use\nAmontons\u2019s/Gay-Lussac\u2019s law. Taking P1 and T1 as the initial values, T2 as the temperature where the pressure\nis unknown and P2 as the unknown pressure, and converting \u00b0C to K, we have:\n"]], ["block_10", ["Rearranging and solving gives:\n"]], ["block_11", [" Check Your Learning \n"]], ["block_12", ["A sample of nitrogen, N2, occupies 45.0 mL at 27 \u00b0C and 600 torr. What pressure will it have if cooled to \u201373 \u00b0C\nwhile the volume remains constant?\n"]], ["block_13", [" Answer: \n400 torr\n"]], ["block_14", [" Volume and Temperature: Charles\u2019s Law \n"]], ["block_15", ["If we fill a balloon with air and seal it, the balloon contains a specific amount of air at atmospheric pressure,\nlet\u2019s say 1 atm. If we put the balloon in a refrigerator, the gas inside gets cold and the balloon shrinks (although\nboth the amount of gas and its pressure remain constant). If we make the balloon very cold, it will shrink a\ngreat deal, and it expands again when it warms up.\n"]], ["block_16", ["This video (http://openstax.org/l/16CharlesLaw) shows how cooling and heating a gas causes its volume to\ndecrease or increase, respectively.\n"]], ["block_17", ["These examples of the effect of temperature on the volume of a given amount of a confined gas at constant\npressure are true in general: The volume increases as the temperature increases, and decreases as the\ntemperature decreases. Volume-temperature data for a 1-mole sample of methane gas at 1 atm are listed and\ngraphed in Figure 9.12.\n"]], ["block_18", ["LINK TO LEARNING\n"]], ["block_19", ["EXAMPLE 9.5\n"]], ["block_20", ["and\nwhich reduces to\nThis equation is useful for pressure-temperature\n"]], ["block_21", [" 9.2 \u2022 Relating Pressure, Volume, Amount, and Temperature: The Ideal Gas Law \n 427 \n"]]], "page_441": [["block_0", [" 428 \n 9 \u2022 Gases \n"]], ["block_1", ["The relationship between the volume and temperature of a given amount of gas at constant pressure is known\nas Charles\u2019s law in recognition of the French scientist and balloon flight pioneer Jacques Alexandre C\u00e9sar\nCharles. Charles\u2019s law states that the volume of a given amount of gas is directly proportional to its\ntemperature on the kelvin scale when the pressure is held constant.\n"]], ["block_2", [{"image_0": "441_0.png", "coords": [72, 57, 540, 231]}]], ["block_3", [" FIGURE 9.12 \nThe volume and temperature are linearly related for 1 mole of methane gas at a constant pressure of\n"]], ["block_4", ["1 atm. If the temperature is in kelvin, volume and temperature are directly proportional. The line stops at 111 K\nbecause methane liquefies at this temperature; when extrapolated, it intersects the graph\u2019s origin, representing a\ntemperature of absolute zero.\n"]], ["block_5", ["Mathematically, this can be written as:\n"]], ["block_6", ["with k being a proportionality constant that depends on the amount and pressure of the gas.\n"]], ["block_7", ["For a confined, constant pressure gas sample,\nis constant (i.e., the ratio = k), and as seen with the P-T\n"]], ["block_8", ["relationship, this leads to another form of Charles\u2019s law:\n"]], ["block_9", [" Predicting Change in Volume with Temperature \n"]], ["block_10", ["A sample of carbon dioxide, CO2, occupies 0.300 L at 10 \u00b0C and 750 torr. What volume will the gas have at 30 \u00b0C\nand 750 torr?\n"]], ["block_11", [" Solution \n"]], ["block_12", ["Because we are looking for the volume change caused by a temperature change at constant pressure, this is a\njob for Charles\u2019s law. Taking V1 and T1 as the initial values, T2 as the temperature at which the volume is\nunknown and V2 as the unknown volume, and converting \u00b0C into K we have:\n"]], ["block_13", ["Rearranging and solving gives:\n"]], ["block_14", ["This answer supports our expectation from Charles\u2019s law, namely, that raising the gas temperature (from 283 K\nto 303 K) at a constant pressure will yield an increase in its volume (from 0.300 L to 0.321 L).\n"]], ["block_15", [" Check Your Learning \n"]], ["block_16", ["A sample of oxygen, O2, occupies 32.2 mL at 30 \u00b0C and 452 torr. What volume will it occupy at \u201370 \u00b0C and the\nsame pressure?\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["EXAMPLE 9.6\n"]]], "page_442": [["block_0", [" Answer: \n21.6 mL\n"]], ["block_1", [" Measuring Temperature with a Volume Change \n"]], ["block_2", ["Temperature is sometimes measured with a gas thermometer by observing the change in the volume of the\ngas as the temperature changes at constant pressure. The hydrogen in a particular hydrogen gas thermometer\nhas a volume of 150.0 cmwhen immersed in a mixture of ice and water (0.00 \u00b0C). When immersed in boiling\nliquid ammonia, the volume of the hydrogen, at the same pressure, is 131.7 cm. Find the temperature of\nboiling ammonia on the kelvin and Celsius scales.\n"]], ["block_3", [" Solution \n"]], ["block_4", ["A volume change caused by a temperature change at constant pressure means we should use Charles\u2019s law.\nTaking V1 and T1 as the initial values, T2 as the temperature at which the volume is unknown and V2 as the\nunknown volume, and converting \u00b0C into K we have:\n"]], ["block_5", ["Rearrangement gives\n"]], ["block_6", ["Subtracting 273.15 from 239.8 K, we find that the temperature of the boiling ammonia on the Celsius scale is\n\u201333.4 \u00b0C.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["What is the volume of a sample of ethane at 467 K and 1.1 atm if it occupies 405 mL at 298 K and 1.1 atm?\n"]], ["block_9", [" Answer: \n635 mL\n"]], ["block_10", [" Volume and Pressure: Boyle\u2019s Law \n"]], ["block_11", ["If we partially fill an airtight syringe with air, the syringe contains a specific amount of air at constant\ntemperature, say 25 \u00b0C. If we slowly push in the plunger while keeping temperature constant, the gas in the\nsyringe is compressed into a smaller volume and its pressure increases; if we pull out the plunger, the volume\nincreases and the pressure decreases. This example of the effect of volume on the pressure of a given amount\nof a confined gas is true in general. Decreasing the volume of a contained gas will increase its pressure, and\nincreasing its volume will decrease its pressure. In fact, if the volume increases by a certain factor, the\npressure decreases by the same factor, and vice versa. Volume-pressure data for an air sample at room\ntemperature are graphed in Figure 9.13.\n"]], ["block_12", ["EXAMPLE 9.7\n"]], ["block_13", [" 9.2 \u2022 Relating Pressure, Volume, Amount, and Temperature: The Ideal Gas Law \n 429 \n"]]], "page_443": [["block_0", [" 430 \n 9 \u2022 Gases \n"]], ["block_1", ["Unlike the P-T and V-T relationships, pressure and volume are not directly proportional to each other. Instead,\nP and V exhibit inverse proportionality: Increasing the pressure results in a decrease of the volume of the gas.\nMathematically this can be written:\n"]], ["block_2", [{"image_0": "443_0.png", "coords": [72, 57, 540, 474]}]], ["block_3", [" FIGURE 9.13 \nWhen a gas occupies a smaller volume, it exerts a higher pressure; when it occupies a larger volume,\n"]], ["block_4", ["it exerts a lower pressure (assuming the amount of gas and the temperature do not change). Since P and V are\ninversely proportional, a graph of\nvs. V is linear.\n"]], ["block_5", ["with k being a constant. Graphically, this relationship is shown by the straight line that results when plotting\nthe inverse of the pressure\nversus the volume (V), or the inverse of volume\nversus the pressure (P).\n"]], ["block_6", ["Graphs with curved lines are difficult to read accurately at low or high values of the variables, and they are\nmore difficult to use in fitting theoretical equations and parameters to experimental data. For those reasons,\nscientists often try to find a way to \u201clinearize\u201d their data. If we plot P versus V, we obtain a hyperbola (see\nFigure 9.14).\n"]], ["block_7", [" Access for free at openstax.org \n"]]], "page_444": [["block_0", ["The relationship between the volume and pressure of a given amount of gas at constant temperature was first\npublished by the English natural philosopher Robert Boyle over 300 years ago. It is summarized in the\nstatement now known as Boyle\u2019s law : The volume of a given amount of gas held at constant temperature is\ninversely proportional to the pressure under which it is measured.\n"]], ["block_1", [" FIGURE 9.14 \nThe relationship between pressure and volume is inversely proportional. (a) The graph of P vs. V is a\n"]], ["block_2", ["hyperbola, whereas (b) the graph of\nvs. V is linear.\n"]], ["block_3", [" Volume of a Gas Sample \n"]], ["block_4", ["The sample of gas in Figure 9.13 has a volume of 15.0 mL at a pressure of 13.0 psi. Determine the pressure of\nthe gas at a volume of 7.5 mL, using:\n"]], ["block_5", ["(a) the P-V graph in Figure 9.13\n"]], ["block_6", ["(b) the\nvs. V graph in Figure 9.13\n"]], ["block_7", ["(c) the Boyle\u2019s law equation\n"]], ["block_8", ["Comment on the likely accuracy of each method.\n"]], ["block_9", [" Solution \n"]], ["block_10", ["(a) Estimating from the P-V graph gives a value for P somewhere around 27 psi.\n"]], ["block_11", ["(b) Estimating from the\nversus V graph give a value of about 26 psi.\n"]], ["block_12", ["(c) From Boyle\u2019s law, we know that the product of pressure and volume (PV) for a given sample of gas at a\nconstant temperature is always equal to the same value. Therefore we have P1V1 = k and P2V2 = k which means\nthat P1V1 = P2V2.\n"]], ["block_13", ["Using P1 and V1 as the known values 13.0 psi and 15.0 mL, P2 as the pressure at which the volume is unknown,\nand V2 as the unknown volume, we have:\n"]], ["block_14", ["Solving:\n"]], ["block_15", ["It was more difficult to estimate well from the P-V graph, so (a) is likely more inaccurate than (b) or (c). The\ncalculation will be as accurate as the equation and measurements allow.\n"]], ["block_16", [" Check Your Learning \n"]], ["block_17", ["The sample of gas in Figure 9.13 has a volume of 30.0 mL at a pressure of 6.5 psi. Determine the volume of the\ngas at a pressure of 11.0 psi, using:\n"]], ["block_18", ["(a) the P-V graph in Figure 9.13\n"]], ["block_19", ["EXAMPLE 9.8\n"]], ["block_20", [{"image_0": "444_0.png", "coords": [189, 57, 423, 176]}]], ["block_21", [" 9.2 \u2022 Relating Pressure, Volume, Amount, and Temperature: The Ideal Gas Law \n 431 \n"]]], "page_445": [["block_0", [" 432 \n 9 \u2022 Gases \n"]], ["block_1", ["(b) the\nvs. V graph in Figure 9.13\n"]], ["block_2", ["(c) the Boyle\u2019s law equation\n"]], ["block_3", ["Comment on the likely accuracy of each method.\n"]], ["block_4", [" Answer: \n(a) about 17\u201318 mL; (b) ~18 mL; (c) 17.7 mL; it was more difficult to estimate well from the P-V graph, so (a) is\nlikely more inaccurate than (b); the calculation will be as accurate as the equation and measurements allow\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", ["Chemistry in Everyday Life\n"]], ["block_7", [" Breathing and Boyle\u2019s Law \nWhat do you do about 20 times per minute for your whole life, without break, and often without even being\naware of it? The answer, of course, is respiration, or breathing. How does it work? It turns out that the gas\nlaws apply here. Your lungs take in gas that your body needs (oxygen) and get rid of waste gas (carbon\ndioxide). Lungs are made of spongy, stretchy tissue that expands and contracts while you breathe. When\nyou inhale, your diaphragm and intercostal muscles (the muscles between your ribs) contract, expanding\nyour chest cavity and making your lung volume larger. The increase in volume leads to a decrease in\npressure (Boyle\u2019s law). This causes air to flow into the lungs (from high pressure to low pressure). When you\nexhale, the process reverses: Your diaphragm and rib muscles relax, your chest cavity contracts, and your\nlung volume decreases, causing the pressure to increase (Boyle\u2019s law again), and air flows out of the lungs\n(from high pressure to low pressure). You then breathe in and out again, and again, repeating this Boyle\u2019s\nlaw cycle for the rest of your life (Figure 9.15).\n"]], ["block_8", [" FIGURE 9.15 \nBreathing occurs because expanding and contracting lung volume creates small pressure\n"]], ["block_9", ["differences between your lungs and your surroundings, causing air to be drawn into and forced out of your lungs.\n"]], ["block_10", [{"image_0": "445_0.png", "coords": [90, 364, 522, 688]}]]], "page_446": [["block_0", ["The Italian scientist Amedeo Avogadro advanced a hypothesis in 1811 to account for the behavior of gases,\nstating that equal volumes of all gases, measured under the same conditions of temperature and pressure,\ncontain the same number of molecules. Over time, this relationship was supported by many experimental\nobservations as expressed by Avogadro\u2019s law : For a confined gas, the volume (V) and number of moles (n) are\ndirectly proportional if the pressure and temperature both remain constant.\n"]], ["block_1", [" Moles of Gas and Volume: Avogadro\u2019s Law \n"]], ["block_2", ["In equation form, this is written as:\n"]], ["block_3", ["Mathematical relationships can also be determined for the other variable pairs, such as P versus n, and n\nversus T.\n"]], ["block_4", ["Visit this interactive PhET simulation (http://openstax.org/l/16IdealGasLaw) to investigate the relationships\nbetween pressure, volume, temperature, and amount of gas. Use the simulation to examine the effect of\nchanging one parameter on another while holding the other parameters constant (as described in the\npreceding sections on the various gas laws).\n"]], ["block_5", [" The Ideal Gas Law \n"]], ["block_6", ["To this point, four separate laws have been discussed that relate pressure, volume, temperature, and the\nnumber of moles of the gas:\n"]], ["block_7", ["Combining these four laws yields the ideal gas law , a relation between the pressure, volume, temperature, and\nnumber of moles of a gas:\n"]], ["block_8", ["where P is the pressure of a gas, V is its volume, n is the number of moles of the gas, T is its temperature on the\nkelvin scale, and R is a constant called the ideal gas constant or the universal gas constant. The units used to\nexpress pressure, volume, and temperature will determine the proper form of the gas constant as required by\ndimensional analysis, the most commonly encountered values being 0.08206 L atm molKand 8.314 kPa L\nmolK.\n"]], ["block_9", ["Gases whose properties of P, V, and T are accurately described by the ideal gas law (or the other gas laws) are\nsaid to exhibit ideal behavior or to approximate the traits of an ideal gas . An ideal gas is a hypothetical\nconstruct that may be used along with kinetic molecular theory to effectively explain the gas laws as will be\ndescribed in a later module of this chapter. Although all the calculations presented in this module assume\nideal behavior, this assumption is only reasonable for gases under conditions of relatively low pressure and\nhigh temperature. In the final module of this chapter, a modified gas law will be introduced that accounts for\nthe non-ideal behavior observed for many gases at relatively high pressures and low temperatures.\n"]], ["block_10", ["The ideal gas equation contains five terms, the gas constant R and the variable properties P, V, n, and T.\nSpecifying any four of these terms will permit use of the ideal gas law to calculate the fifth term as\ndemonstrated in the following example exercises.\n"]], ["block_11", ["\u2022\nBoyle\u2019s law: PV = constant at constant T and n\n"]], ["block_12", ["\u2022\nAmontons\u2019s law:\n= constant at constant V and n\n"]], ["block_13", ["\u2022\nCharles\u2019s law:\n= constant at constant P and n\n"]], ["block_14", ["\u2022\nAvogadro\u2019s law:\n= constant at constant P and T\n"]], ["block_15", ["LINK TO LEARNING\n"]], ["block_16", [" 9.2 \u2022 Relating Pressure, Volume, Amount, and Temperature: The Ideal Gas Law \n 433 \n"]]], "page_447": [["block_0", [" 434 \n 9 \u2022 Gases \n"]], ["block_1", [" Using the Ideal Gas Law \n"]], ["block_2", ["Methane, CH4, is being considered for use as an alternative automotive fuel to replace gasoline. One gallon of\ngasoline could be replaced by 655 g of CH4. What is the volume of this much methane at 25 \u00b0C and 745 torr?\n"]], ["block_3", [" Solution \n"]], ["block_4", ["We must rearrange PV = nRT to solve for V:\n"]], ["block_5", ["If we choose to use R = 0.08206 L atm molK, then the amount must be in moles, temperature must be in\nkelvin, and pressure must be in atm.\n"]], ["block_6", ["Converting into the \u201cright\u201d units:\n"]], ["block_7", ["It would require 1020 L (269 gal) of gaseous methane at about 1 atm of pressure to replace 1 gal of gasoline. It\nrequires a large container to hold enough methane at 1 atm to replace several gallons of gasoline.\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["Calculate the pressure in bar of 2520 moles of hydrogen gas stored at 27 \u00b0C in the 180-L storage tank of a\nmodern hydrogen-powered car.\n"]], ["block_10", [" Answer: \n350 bar\n"]], ["block_11", ["If the number of moles of an ideal gas are kept constant under two different sets of conditions, a useful\n"]], ["block_12", ["mathematical relationship called the combined gas law is obtained:\nusing units of atm, L, and\n"]], ["block_13", ["K. Both sets of conditions are equal to the product of n\nR (where n = the number of moles of the gas and R is\n"]], ["block_14", ["the ideal gas law constant).\n"]], ["block_15", [" Using the Combined Gas Law \n"]], ["block_16", ["When filled with air, a typical scuba tank with a volume of 13.2 L has a pressure of 153 atm (Figure 9.16). If the\nwater temperature is 27 \u00b0C, how many liters of air will such a tank provide to a diver\u2019s lungs at a depth of\napproximately 70 feet in the ocean where the pressure is 3.13 atm?\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["EXAMPLE 9.9\n"]], ["block_19", ["EXAMPLE 9.10\n"]]], "page_448": [["block_0", [" FIGURE 9.16 \nScuba divers use compressed air to breathe while underwater. (credit: modification of work by Mark\n"]], ["block_1", ["Goodchild)\n"]], ["block_2", ["Letting 1 represent the air in the scuba tank and 2 represent the air in the lungs, and noting that body\ntemperature (the temperature the air will be in the lungs) is 37 \u00b0C, we have:\n"]], ["block_3", ["Solving for V2:\n"]], ["block_4", ["(Note: Be advised that this particular example is one in which the assumption of ideal gas behavior is not very\nreasonable, since it involves gases at relatively high pressures and low temperatures. Despite this limitation,\nthe calculated volume can be viewed as a good \u201cballpark\u201d estimate.)\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["A sample of ammonia is found to occupy 0.250 L under laboratory conditions of 27 \u00b0C and 0.850 atm. Find the\nvolume of this sample at 0 \u00b0C and 1.00 atm.\n"]], ["block_7", [" Answer: \n0.193 L\n"]], ["block_8", ["Chemistry in Everyday Life\n"]], ["block_9", [" The Interdependence between Ocean Depth and Pressure in Scuba Diving \nWhether scuba diving at the Great Barrier Reef in Australia (shown in Figure 9.17) or in the Caribbean,\ndivers must understand how pressure affects a number of issues related to their comfort and safety.\n"]], ["block_10", [{"image_0": "448_0.png", "coords": [189, 57, 423, 227]}]], ["block_11", [" 9.2 \u2022 Relating Pressure, Volume, Amount, and Temperature: The Ideal Gas Law \n 435 \n"]]], "page_449": [["block_0", [" 436 \n 9 \u2022 Gases \n"]], ["block_1", [" Standard Conditions of Temperature and Pressure \n"]], ["block_2", ["We have seen that the volume of a given quantity of gas and the number of molecules (moles) in a given volume\nof gas vary with changes in pressure and temperature. Chemists sometimes make comparisons against a\n standard temperature and pressure (STP) for reporting properties of gases: 273.15 K and 1 atm (101.325\nkPa).At STP, one mole of an ideal gas has a volume of about 22.4 L\u2014this is referred to as the standard molar \n volume (Figure 9.18).\n"]], ["block_3", ["1 The IUPAC definition of standard pressure was changed from 1 atm to 1 bar (100 kPa) in 1982, but the prior definition remains in\nuse by many literature resources and will be used in this text.\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", [" FIGURE 9.17 \nScuba divers, whether at the Great Barrier Reef or in the Caribbean, must be aware of buoyancy,\n"]], ["block_6", ["pressure equalization, and the amount of time they spend underwater, to avoid the risks associated with\npressurized gases in the body. (credit: Kyle Taylor)\n"]], ["block_7", ["Pressure increases with ocean depth, and the pressure changes most rapidly as divers reach the surface.\nThe pressure a diver experiences is the sum of all pressures above the diver (from the water and the air).\nMost pressure measurements are given in units of atmospheres, expressed as \u201catmospheres absolute\u201d or\nATA in the diving community: Every 33 feet of salt water represents 1 ATA of pressure in addition to 1 ATA\nof pressure from the atmosphere at sea level. As a diver descends, the increase in pressure causes the\nbody\u2019s air pockets in the ears and lungs to compress; on the ascent, the decrease in pressure causes these\nair pockets to expand, potentially rupturing eardrums or bursting the lungs. Divers must therefore\nundergo equalization by adding air to body airspaces on the descent by breathing normally and adding air\nto the mask by breathing out of the nose or adding air to the ears and sinuses by equalization techniques;\nthe corollary is also true on ascent, divers must release air from the body to maintain equalization.\nBuoyancy, or the ability to control whether a diver sinks or floats, is controlled by the buoyancy\ncompensator (BCD). If a diver is ascending, the air in their BCD expands because of lower pressure\naccording to Boyle\u2019s law (decreasing the pressure of gases increases the volume). The expanding air\nincreases the buoyancy of the diver, and they begin to ascend. The diver must vent air from the BCD or risk\nan uncontrolled ascent that could rupture the lungs. In descending, the increased pressure causes the air\nin the BCD to compress and the diver sinks much more quickly; the diver must add air to the BCD or risk an\nuncontrolled descent, facing much higher pressures near the ocean floor. The pressure also impacts how\nlong a diver can stay underwater before ascending. The deeper a diver dives, the more compressed the air\nthat is breathed because of increased pressure: If a diver dives 33 feet, the pressure is 2 ATA and the air\nwould be compressed to one-half of its original volume. The diver uses up available air twice as fast as at\nthe surface.\n"]], ["block_8", [{"image_0": "449_0.png", "coords": [189, 57, 423, 232]}]]], "page_450": [["block_0", [{"image_0": "450_0.png", "coords": [72, 57, 540, 327]}]], ["block_1", [" FIGURE 9.18 \nRegardless of its chemical identity, one mole of gas behaving ideally occupies a volume of ~22.4 L at\n"]], ["block_2", ["STP.\n"]], ["block_3", [" 9.3 Stoichiometry of Gaseous Substances, Mixtures, and Reactions \n"]], ["block_4", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_5", ["The study of the chemical behavior of gases was part of the basis of perhaps the most fundamental chemical\nrevolution in history. French nobleman Antoine Lavoisier, widely regarded as the \u201cfather of modern\nchemistry,\u201d changed chemistry from a qualitative to a quantitative science through his work with gases. He\ndiscovered the law of conservation of matter, discovered the role of oxygen in combustion reactions,\ndetermined the composition of air, explained respiration in terms of chemical reactions, and more. He was a\ncasualty of the French Revolution, guillotined in 1794. Of his death, mathematician and astronomer Joseph-\nLouis Lagrange said, \u201cIt took the mob only a moment to remove his head; a century will not suffice to\nreproduce it.\u201dMuch of the knowledge we do have about Lavoisier's contributions is due to his wife, Marie-\nAnne Paulze Lavoisier, who worked with him in his lab. A trained artist fluent in several languages, she created\ndetailed illustrations of the equipment in his lab, and translated texts from foreign scientists to complement\nhis knowledge. After his execution, she was instrumental in publishing Lavoisier's major treatise, which\nunified many concepts of chemistry and laid the groundwork for significant further study.\n"]], ["block_6", ["As described in an earlier chapter of this text, we can turn to chemical stoichiometry for answers to many of\nthe questions that ask \u201cHow much?\u201d The essential property involved in such use of stoichiometry is the\namount of substance, typically measured in moles (n). For gases, molar amount can be derived from\nconvenient experimental measurements of pressure, temperature, and volume. Therefore, these\nmeasurements are useful in assessing the stoichiometry of pure gases, gas mixtures, and chemical reactions\ninvolving gases. This section will not introduce any new material or ideas, but will provide examples of\napplications and ways to integrate concepts already discussed.\n"]], ["block_7", ["2 \u201cQuotations by Joseph-Louis Lagrange,\u201d last modified February 2006, accessed February 10, 2015, http://www-history.mcs.st-\nandrews.ac.uk/Quotations/Lagrange.html\n"]], ["block_8", ["\u2022\nUse the ideal gas law to compute gas densities and molar masses\n"]], ["block_9", ["\u2022\nPerform stoichiometric calculations involving gaseous substances\n"]], ["block_10", ["\u2022\nState Dalton\u2019s law of partial pressures and use it in calculations involving gaseous mixtures\n"]], ["block_11", [" 9.3 \u2022 Stoichiometry of Gaseous Substances, Mixtures, and Reactions \n 437 \n"]]], "page_451": [["block_0", [" 438 \n 9 \u2022 Gases \n"]], ["block_1", [" Gas Density and Molar Mass \n"]], ["block_2", ["The ideal gas law described previously in this chapter relates the properties of pressure P, volume V,\ntemperature T, and molar amount n. This law is universal, relating these properties in identical fashion\nregardless of the chemical identity of the gas:\n"]], ["block_3", ["The density d of a gas, on the other hand, is determined by its identity. As described in another chapter of this\ntext, the density of a substance is a characteristic property that may be used to identify the substance.\n"]], ["block_4", ["Rearranging the ideal gas equation to isolate V and substituting into the density equation yields\n"]], ["block_5", ["The ratio m/n is the definition of molar mass, \u2133:\n"]], ["block_6", ["The density equation can then be written\n"]], ["block_7", ["This relation may be used for calculating the densities of gases of known identities at specified values of\npressure and temperature as demonstrated in Example 9.11.\n"]], ["block_8", [" Measuring Gas Density \n"]], ["block_9", ["What is the density of molecular nitrogen gas at STP?\n"]], ["block_10", [" Solution \n"]], ["block_11", ["The molar mass of molecular nitrogen, N2, is 28.01 g/mol. Substituting this value along with standard\ntemperature and pressure into the gas density equation yields\n"]], ["block_12", [" Check Your Learning \n"]], ["block_13", ["What is the density of molecular hydrogen gas at 17.0 \u00b0C and a pressure of 760 torr?\n"]], ["block_14", [" Answer: \nd = 0.0847 g/L\n"]], ["block_15", ["When the identity of a gas is unknown, measurements of the mass, pressure, volume, and temperature of a\nsample can be used to calculate the molar mass of the gas (a useful property for identification purposes).\nCombining the ideal gas equation\n"]], ["block_16", ["and the definition of molar mass\n"]], ["block_17", ["yields the following equation:\n"]], ["block_18", [" Access for free at openstax.org \n"]], ["block_19", ["EXAMPLE 9.11\n"]]], "page_452": [["block_0", ["Determining the molar mass of a gas via this approach is demonstrated in Example 9.12.\n"]], ["block_1", [" Determining the Molecular Formula of a Gas from its Molar Mass and Empirical Formula \n"]], ["block_2", ["Cyclopropane, a gas once used with oxygen as a general anesthetic, is composed of 85.7% carbon and 14.3%\nhydrogen by mass. Find the empirical formula. If 1.56 g of cyclopropane occupies a volume of 1.00 L at 0.984\natm and 50 \u00b0C, what is the molecular formula for cyclopropane?\n"]], ["block_3", [" Solution \n"]], ["block_4", ["First determine the empirical formula of the gas. Assume 100 g and convert the percentage of each element\ninto grams. Determine the number of moles of carbon and hydrogen in the 100-g sample of cyclopropane.\nDivide by the smallest number of moles to relate the number of moles of carbon to the number of moles of\nhydrogen. In the last step, realize that the smallest whole number ratio is the empirical formula:\n"]], ["block_5", ["Empirical formula is CH2 [empirical mass (EM) of 14.03 g/empirical unit].\n"]], ["block_6", ["Next, use the provided values for mass, pressure, temperature and volume to compute the molar mass of the\ngas:\n"]], ["block_7", ["Comparing the molar mass to the empirical formula mass shows how many empirical formula units make up a\nmolecule:\n"]], ["block_8", ["The molecular formula is thus derived from the empirical formula by multiplying each of its subscripts by\nthree:\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["Acetylene, a fuel used welding torches, is composed of 92.3% C and 7.7% H by mass. Find the empirical\nformula. If 1.10 g of acetylene occupies of volume of 1.00 L at 1.15 atm and 59.5 \u00b0C, what is the molecular\nformula for acetylene?\n"]], ["block_11", [" Answer: \nEmpirical formula, CH; Molecular formula, C2H2\n"]], ["block_12", [" Determining the Molar Mass of a Volatile Liquid \n"]], ["block_13", ["The approximate molar mass of a volatile liquid can be determined by:\n"]], ["block_14", ["1.\nHeating a sample of the liquid in a flask with a tiny hole at the top, which converts the liquid into gas that\n"]], ["block_15", ["EXAMPLE 9.12\n"]], ["block_16", ["EXAMPLE 9.13\n"]], ["block_17", [" 9.3 \u2022 Stoichiometry of Gaseous Substances, Mixtures, and Reactions \n 439 \n"]]], "page_453": [["block_0", [" 440 \n 9 \u2022 Gases \n"]], ["block_1", ["Unless they chemically react with each other, the individual gases in a mixture of gases do not affect each\nother\u2019s pressure. Each individual gas in a mixture exerts the same pressure that it would exert if it were\npresent alone in the container (Figure 9.20). The pressure exerted by each individual gas in a mixture is called\nits partial pressure . This observation is summarized by Dalton\u2019s law of partial pressures : The total pressure\nof a mixture of ideal gases is equal to the sum of the partial pressures of the component gases:\n"]], ["block_2", [" FIGURE 9.19 \nWhen the volatile liquid in the flask is heated past its boiling point, it becomes gas and drives air out\n"]], ["block_3", ["of the flask. At\nthe flask is filled with volatile liquid gas at the same pressure as the atmosphere. If the flask\n"]], ["block_4", ["is then cooled to room temperature, the gas condenses and the mass of the gas that filled the flask, and is now\nliquid, can be measured. (credit: modification of work by Mark Ott)\n"]], ["block_5", ["Using this procedure, a sample of chloroform gas weighing 0.494 g is collected in a flask with a volume of 129\ncmat 99.6 \u00b0C when the atmospheric pressure is 742.1 mm Hg. What is the approximate molar mass of\nchloroform?\n"]], ["block_6", [" Solution \n"]], ["block_7", ["Since \u2133\nand\nsubstituting and rearranging gives \u2133\n"]], ["block_8", ["then\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["A sample of phosphorus that weighs 3.243\n10g exerts a pressure of 31.89 kPa in a 56.0-mL bulb at 550 \u00b0C.\n"]], ["block_11", ["What are the molar mass and molecular formula of phosphorus vapor?\n"]], ["block_12", [" Answer: \n124 g/mol P4\n"]], ["block_13", [" The Pressure of a Mixture of Gases: Dalton\u2019s Law \n"]], ["block_14", ["In the equation PTotal is the total pressure of a mixture of gases, PA is the partial pressure of gas A; PB is the\npartial pressure of gas B; PC is the partial pressure of gas C; and so on.\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["2.\nRemoving the flask from heat at the instant when the last bit of liquid becomes gas, at which time the flask\nwill be filled with only gaseous sample at ambient pressure\n"]], ["block_17", ["3.\nSealing the flask and permitting the gaseous sample to condense to liquid, and then weighing the flask to\ndetermine the sample\u2019s mass (see Figure 9.19)\n"]], ["block_18", ["may escape through the hole\n"]], ["block_19", [{"image_0": "453_0.png", "coords": [126, 126, 486, 214]}]], ["block_20", ["\u2133\n"]]], "page_454": [["block_0", ["where PA, XA, and nA are the partial pressure, mole fraction, and number of moles of gas A, respectively, and\nnTotal is the number of moles of all components in the mixture.\n"]], ["block_1", [{"image_0": "454_0.png", "coords": [72, 57, 540, 267]}]], ["block_2", [" FIGURE 9.20 \nIf equal-volume cylinders containing gasses at pressures of 300 kPa, 450 kPa, and 600 kPa are all\n"]], ["block_3", ["combined in the same-size cylinder, the total pressure of the gas mixture is 1350 kPa.\n"]], ["block_4", ["The partial pressure of gas A is related to the total pressure of the gas mixture via its mole fraction (X) , a unit\nof concentration defined as the number of moles of a component of a solution divided by the total number of\nmoles of all components:\n"]], ["block_5", [" The Pressure of a Mixture of Gases \n"]], ["block_6", ["A 10.0-L vessel contains 2.50\n10mol of H2, 1.00\n10mol of He, and 3.00\n10mol of Ne at 35 \u00b0C.\n"]], ["block_7", ["(a) What are the partial pressures of each of the gases?\n"]], ["block_8", ["(b) What is the total pressure in atmospheres?\n"]], ["block_9", [" Solution \n"]], ["block_10", ["The gases behave independently, so the partial pressure of each gas can be determined from the ideal gas\nequation, using\n:\n"]], ["block_11", ["The total pressure is given by the sum of the partial pressures:\n"]], ["block_12", ["EXAMPLE 9.14\n"]], ["block_13", [" 9.3 \u2022 Stoichiometry of Gaseous Substances, Mixtures, and Reactions \n 441 \n"]]], "page_455": [["block_0", [" 442 \n 9 \u2022 Gases \n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["A 5.73-L flask at 25 \u00b0C contains 0.0388 mol of N2, 0.147 mol of CO, and 0.0803 mol of H2. What is the total\npressure in the flask in atmospheres?\n"]], ["block_3", [" Answer: \n1.137 atm\n"]], ["block_4", ["Here is another example of this concept, but dealing with mole fraction calculations.\n"]], ["block_5", [" The Pressure of a Mixture of Gases \n"]], ["block_6", ["A gas mixture used for anesthesia contains 2.83 mol oxygen, O2, and 8.41 mol nitrous oxide, N2O. The total\npressure of the mixture is 192 kPa.\n"]], ["block_7", ["(a) What are the mole fractions of O2 and N2O?\n"]], ["block_8", ["(b) What are the partial pressures of O2 and N2O?\n"]], ["block_9", [" Solution \n"]], ["block_10", ["The mole fraction is given by\nand the partial pressure is PA = XA\nPTotal.\n"]], ["block_11", ["For O2,\n"]], ["block_12", ["and\n"]], ["block_13", ["For N2O,\n"]], ["block_14", ["and\n"]], ["block_15", [" Check Your Learning \n"]], ["block_16", ["What is the pressure of a mixture of 0.200 g of H2, 1.00 g of N2, and 0.820 g of Ar in a container with a volume\nof 2.00 L at 20 \u00b0C?\n"]], ["block_17", [" Answer: \n1.87 atm\n"]], ["block_18", [" Collection of Gases over Water \n"]], ["block_19", ["A simple way to collect gases that do not react with water is to capture them in a bottle that has been filled with\nwater and inverted into a dish filled with water. The pressure of the gas inside the bottle can be made equal to\nthe air pressure outside by raising or lowering the bottle. When the water level is the same both inside and\noutside the bottle (Figure 9.21), the pressure of the gas is equal to the atmospheric pressure, which can be\nmeasured with a barometer.\n"]], ["block_20", [" Access for free at openstax.org \n"]], ["block_21", ["EXAMPLE 9.15\n"]]], "page_456": [["block_0", [" FIGURE 9.21 \nWhen a reaction produces a gas that is collected above water, the trapped gas is a mixture of the gas\n"]], ["block_1", ["produced by the reaction and water vapor. If the collection flask is appropriately positioned to equalize the water\nlevels both within and outside the flask, the pressure of the trapped gas mixture will equal the atmospheric pressure\noutside the flask (see the earlier discussion of manometers).\n"]], ["block_2", ["However, there is another factor we must consider when we measure the pressure of the gas by this method.\nWater evaporates and there is always gaseous water (water vapor) above a sample of liquid water. As a gas is\ncollected over water, it becomes saturated with water vapor and the total pressure of the mixture equals the\npartial pressure of the gas plus the partial pressure of the water vapor. The pressure of the pure gas is\ntherefore equal to the total pressure minus the pressure of the water vapor\u2014this is referred to as the \u201cdry\u201d gas\npressure, that is, the pressure of the gas only, without water vapor. The vapor pressure of water , which is the\npressure exerted by water vapor in equilibrium with liquid water in a closed container, depends on the\ntemperature (Figure 9.22); more detailed information on the temperature dependence of water vapor can be\nfound in Table 9.2, and vapor pressure will be discussed in more detail in the next chapter on liquids.\n"]], ["block_3", [" FIGURE 9.22 \nThis graph shows the vapor pressure of water at sea level as a function of temperature.\n"]], ["block_4", [{"image_0": "456_0.png", "coords": [189, 57, 423, 257]}]], ["block_5", [{"image_1": "456_1.png", "coords": [189, 437, 423, 619]}]], ["block_6", [" 9.3 \u2022 Stoichiometry of Gaseous Substances, Mixtures, and Reactions \n 443 \n"]]], "page_457": [["block_0", [" 444 \n 9 \u2022 Gases \n"]], ["block_1", [" TABLE 9.2 \n"]], ["block_2", [" Pressure of a Gas Collected Over Water \n"]], ["block_3", ["If 0.200 L of argon is collected over water at a temperature of 26 \u00b0C and a pressure of 750 torr in a system like\nthat shown in Figure 9.21, what is the partial pressure of argon?\n"]], ["block_4", [" Solution \n"]], ["block_5", ["According to Dalton\u2019s law, the total pressure in the bottle (750 torr) is the sum of the partial pressure of argon\nand the partial pressure of gaseous water:\n"]], ["block_6", ["Rearranging this equation to solve for the pressure of argon gives:\n"]], ["block_7", ["The pressure of water vapor above a sample of liquid water at 26 \u00b0C is 25.2 torr (Appendix E), so:\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["A sample of oxygen collected over water at a temperature of 29.0 \u00b0C and a pressure of 764 torr has a volume of\n0.560 L. What volume would the dry oxygen from this sample have under the same conditions of temperature\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [" Temperature \n (\u00b0C) \n"]], ["block_12", ["\u201310\n1.95\n18\n15.5\n30\n31.8\n"]], ["block_13", ["\u20135\n3.0\n19\n16.5\n35\n42.2\n"]], ["block_14", ["\u20132\n3.9\n20\n17.5\n40\n55.3\n"]], ["block_15", ["0\n4.6\n21\n18.7\n50\n92.5\n"]], ["block_16", ["2\n5.3\n22\n19.8\n60\n149.4\n"]], ["block_17", ["4\n6.1\n23\n21.1\n70\n233.7\n"]], ["block_18", ["6\n7.0\n24\n22.4\n80\n355.1\n"]], ["block_19", ["8\n8.0\n25\n23.8\n90\n525.8\n"]], ["block_20", ["10\n9.2\n26\n25.2\n95\n633.9\n"]], ["block_21", ["12\n10.5\n27\n26.7\n99\n733.2\n"]], ["block_22", ["14\n12.0\n28\n28.3\n100.0\n760.0\n"]], ["block_23", ["16\n13.6\n29\n30.0\n101.0\n787.6\n"]], ["block_24", ["EXAMPLE 9.16\n"]], ["block_25", ["Vapor Pressure of Ice and Water in Various Temperatures at Sea Level\n"]], ["block_26", [" Pressure \n (torr) \n"]], ["block_27", [" Temperature \n (\u00b0C) \n"]], ["block_28", [" Pressure \n (torr) \n"]], ["block_29", [" Temperature \n (\u00b0C) \n"]], ["block_30", [" Pressure \n (torr) \n"]]], "page_458": [["block_0", ["and pressure?\n"]], ["block_1", [" Answer: \n0.537 L\n"]], ["block_2", [" Chemical Stoichiometry and Gases \n"]], ["block_3", ["Chemical stoichiometry describes the quantitative relationships between reactants and products in chemical\nreactions.\n"]], ["block_4", ["We have previously measured quantities of reactants and products using masses for solids and volumes in\nconjunction with the molarity for solutions; now we can also use gas volumes to indicate quantities. If we know\nthe volume, pressure, and temperature of a gas, we can use the ideal gas equation to calculate how many moles\nof the gas are present. If we know how many moles of a gas are involved, we can calculate the volume of a gas at\nany temperature and pressure.\n"]], ["block_5", [" Avogadro\u2019s Law Revisited \n"]], ["block_6", ["Sometimes we can take advantage of a simplifying feature of the stoichiometry of gases that solids and\nsolutions do not exhibit: All gases that show ideal behavior contain the same number of molecules in the same\nvolume (at the same temperature and pressure). Thus, the ratios of volumes of gases involved in a chemical\nreaction are given by the coefficients in the equation for the reaction, provided that the gas volumes are\nmeasured at the same temperature and pressure.\n"]], ["block_7", ["We can extend Avogadro\u2019s law (that the volume of a gas is directly proportional to the number of moles of the\ngas) to chemical reactions with gases: Gases combine, or react, in definite and simple proportions by volume,\nprovided that all gas volumes are measured at the same temperature and pressure. For example, since\nnitrogen and hydrogen gases react to produce ammonia gas according to\na\n"]], ["block_8", ["given volume of nitrogen gas reacts with three times that volume of hydrogen gas to produce two times that\nvolume of ammonia gas, if pressure and temperature remain constant.\n"]], ["block_9", ["The explanation for this is illustrated in Figure 9.23. According to Avogadro\u2019s law, equal volumes of gaseous N2,\nH2, and NH3, at the same temperature and pressure, contain the same number of molecules. Because one\nmolecule of N2 reacts with three molecules of H2 to produce two molecules of NH3, the volume of H2 required\nis three times the volume of N2, and the volume of NH3 produced is two times the volume of N2.\n"]], ["block_10", [{"image_0": "458_0.png", "coords": [72, 473, 540, 705]}]], ["block_11", [" FIGURE 9.23 \nOne volume of N2 combines with three volumes of H2 to form two volumes of NH3.\n"]], ["block_12", [" 9.3 \u2022 Stoichiometry of Gaseous Substances, Mixtures, and Reactions \n 445 \n"]]], "page_459": [["block_0", [" 446 \n 9 \u2022 Gases \n"]], ["block_1", [" Reaction of Gases \n"]], ["block_2", ["Propane, C3H8(g), is used in gas grills to provide the heat for cooking. What volume of O2(g) measured at 25 \u00b0C\nand 760 torr is required to react with 2.7 L of propane measured under the same conditions of temperature\nand pressure? Assume that the propane undergoes complete combustion.\n"]], ["block_3", [" Solution \n"]], ["block_4", ["The ratio of the volumes of C3H8 and O2 will be equal to the ratio of their coefficients in the balanced equation\nfor the reaction:\n"]], ["block_5", ["From the equation, we see that one volume of C3H8 will react with five volumes of O2:\n"]], ["block_6", ["A volume of 13.5 L of O2 will be required to react with 2.7 L of C3H8.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["An acetylene tank for an oxyacetylene welding torch provides 9340 L of acetylene gas, C2H2, at 0 \u00b0C and 1 atm.\nHow many tanks of oxygen, each providing 7.00\n10L of O2 at 0 \u00b0C and 1 atm, will be required to burn the\n"]], ["block_9", ["acetylene?\n"]], ["block_10", [" Answer: \n3.34 tanks (2.34\n10L)\n"]], ["block_11", [" Volumes of Reacting Gases \n"]], ["block_12", ["Ammonia is an important fertilizer and industrial chemical. Suppose that a volume of 683 billion cubic feet of\ngaseous ammonia, measured at 25 \u00b0C and 1 atm, was manufactured. What volume of H2(g), measured under\nthe same conditions, was required to prepare this amount of ammonia by reaction with N2?\n"]], ["block_13", [" Solution \n"]], ["block_14", ["Because equal volumes of H2 and NH3 contain equal numbers of molecules and each three molecules of H2\nthat react produce two molecules of NH3, the ratio of the volumes of H2 and NH3 will be equal to 3:2. Two\nvolumes of NH3, in this case in units of billion ft, will be formed from three volumes of H2:\n"]], ["block_15", ["The manufacture of 683 billion ftof NH3 required 1020 billion ftof H2. (At 25 \u00b0C and 1 atm, this is the volume\nof a cube with an edge length of approximately 1.9 miles.)\n"]], ["block_16", [" Check Your Learning \n"]], ["block_17", ["What volume of O2(g) measured at 25 \u00b0C and 760 torr is required to react with 17.0 L of ethylene, C2H4(g),\nmeasured under the same conditions of temperature and pressure? The products are CO2 and water vapor.\n"]], ["block_18", [" Access for free at openstax.org \n"]], ["block_19", ["EXAMPLE 9.17\n"]], ["block_20", ["EXAMPLE 9.18\n"]], ["block_21", ["\u2003\u2003\n\u2003\u2003\n"]]], "page_460": [["block_0", [" Answer: \n51.0 L\n"]], ["block_1", [" Volume of Gaseous Product \n"]], ["block_2", ["What volume of hydrogen at 27 \u00b0C and 723 torr may be prepared by the reaction of 8.88 g of gallium with an\nexcess of hydrochloric acid?\n"]], ["block_3", [" Solution \n"]], ["block_4", ["Convert the provided mass of the limiting reactant, Ga, to moles of hydrogen produced:\n"]], ["block_5", ["Convert the provided temperature and pressure values to appropriate units (K and atm, respectively), and then\nuse the molar amount of hydrogen gas and the ideal gas equation to calculate the volume of gas:\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["Sulfur dioxide is an intermediate in the preparation of sulfuric acid. What volume of SO2 at 343 \u00b0C and 1.21\natm is produced by burning l.00 kg of sulfur in excess oxygen?\n"]], ["block_8", [" Answer: \n1.30\n10L\n"]], ["block_9", [" Greenhouse Gases and Climate Change \nThe thin skin of our atmosphere keeps the earth from being an ice planet and makes it habitable. In fact, this is\ndue to less than 0.5% of the air molecules. Of the energy from the sun that reaches the earth, almost\nis\n"]], ["block_10", ["reflected back into space, with the rest absorbed by the atmosphere and the surface of the earth. Some of the\nenergy that the earth absorbs is re-emitted as infrared (IR) radiation, a portion of which passes back out\nthrough the atmosphere into space. Most if this IR radiation, however, is absorbed by certain atmospheric\ngases, effectively trapping heat within the atmosphere in a phenomenon known as the greenhouse effect. This\neffect maintains global temperatures within the range needed to sustain life on earth. Without our\natmosphere, the earth's average temperature would be lower by more than 30 \u00b0C (nearly 60 \u00b0F). The major\ngreenhouse gases (GHGs) are water vapor, carbon dioxide, methane, and ozone. Since the Industrial\nRevolution, human activity has been increasing the concentrations of GHGs, which have changed the energy\nbalance and are significantly altering the earth\u2019s climate (Figure 9.24).\n"]], ["block_11", ["EXAMPLE 9.19\n"]], ["block_12", ["HOW SCIENCES INTERCONNECT\n"]], ["block_13", [" 9.3 \u2022 Stoichiometry of Gaseous Substances, Mixtures, and Reactions \n 447 \n"]]], "page_461": [["block_0", [" 448 \n 9 \u2022 Gases \n"]], ["block_1", [" FIGURE 9.24 \nGreenhouse gases trap enough of the sun\u2019s energy to make the planet habitable\u2014this is known as\n"]], ["block_2", ["the greenhouse effect. Human activities are increasing greenhouse gas levels, warming the planet and causing more\nextreme weather events.\n"]], ["block_3", ["There is strong evidence from multiple sources that higher atmospheric levels of CO2 are caused by human\nactivity, with fossil fuel burning accounting for about\nof the recent increase in CO2. Reliable data from ice\n"]], ["block_4", ["cores reveals that CO2 concentration in the atmosphere is at the highest level in the past 800,000 years; other\nevidence indicates that it may be at its highest level in 20 million years. In recent years, the CO2 concentration\nhas increased preindustrial levels of ~280 ppm to more than 400 ppm today (Figure 9.25).\n"]], ["block_5", [" FIGURE 9.25 \nCO2 levels over the past 700,000 years were typically from 200\u2013300 ppm, with a steep,\n"]], ["block_6", ["unprecedented increase over the past 50 years.\n"]], ["block_7", ["Click here (http://openstax.org/l/16GlobalWarming) to see a 2-minute video explaining greenhouse gases and\nglobal warming.\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["Portrait of a Chemist\n"]], ["block_10", [" Susan Solomon \nAtmospheric and climate scientist Susan Solomon (Figure 9.26) is the author of one of The New York Times\nbooks of the year (The Coldest March, 2001), one of Time magazine\u2019s 100 most influential people in the\nworld (2008), and a working group leader of the Intergovernmental Panel on Climate Change (IPCC), which\nwas the recipient of the 2007 Nobel Peace Prize. She helped determine and explain the cause of the\nformation of the ozone hole over Antarctica, and has authored many important papers on climate change.\n"]], ["block_11", [{"image_0": "461_0.png", "coords": [90, 334, 522, 495]}]], ["block_12", ["LINK TO LEARNING\n"]], ["block_13", [{"image_1": "461_1.png", "coords": [188, 57, 423, 214]}]]], "page_462": [["block_0", [" 9.4 Effusion and Diffusion of Gases \n"]], ["block_1", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_2", ["If you have ever been in a room when a piping hot pizza was delivered, you have been made aware of the fact\nthat gaseous molecules can quickly spread throughout a room, as evidenced by the pleasant aroma that soon\nreaches your nose. Although gaseous molecules travel at tremendous speeds (hundreds of meters per second),\nthey collide with other gaseous molecules and travel in many different directions before reaching the desired\ntarget. At room temperature, a gaseous molecule will experience billions of collisions per second. The mean \n free path is the average distance a molecule travels between collisions. The mean free path increases with\ndecreasing pressure; in general, the mean free path for a gaseous molecule will be hundreds of times the\ndiameter of the molecule\n"]], ["block_3", ["In general, we know that when a sample of gas is introduced to one part of a closed container, its molecules\nvery quickly disperse throughout the container; this process by which molecules disperse in space in response\nto differences in concentration is called diffusion (shown in Figure 9.27). The gaseous atoms or molecules are,\nof course, unaware of any concentration gradient, they simply move randomly\u2014regions of higher\nconcentration have more particles than regions of lower concentrations, and so a net movement of species\nfrom high to low concentration areas takes place. In a closed environment, diffusion will ultimately result in\nequal concentrations of gas throughout, as depicted in Figure 9.27. The gaseous atoms and molecules continue\nto move, but since their concentrations are the same in both bulbs, the rates of transfer between the bulbs are\nequal (no net transfer of molecules occurs).\n"]], ["block_4", [{"image_0": "462_0.png", "coords": [72, 593, 540, 717]}]], ["block_5", [" FIGURE 9.27 \n(a) Two gases, H2 and O2, are initially separated. (b) When the stopcock is opened, they mix together.\n"]], ["block_6", ["\u2022\nDefine and explain effusion and diffusion\n"]], ["block_7", ["\u2022\nState Graham\u2019s law and use it to compute relevant gas properties\n"]], ["block_8", ["She has been awarded the top scientific honors in the US and France (the National Medal of Science and\nthe Grande Medaille, respectively), and is a member of the National Academy of Sciences, the Royal Society,\nthe French Academy of Sciences, and the European Academy of Sciences. Formerly a professor at the\nUniversity of Colorado, she is now at MIT, and continues to work at NOAA.\n"]], ["block_9", ["For more information, watch this video (http://openstax.org/l/16SusanSolomon) about Susan Solomon.\n"]], ["block_10", [" FIGURE 9.26 \nSusan Solomon\u2019s research focuses on climate change and has been instrumental in determining\n"]], ["block_11", ["the cause of the ozone hole over Antarctica. (credit: National Oceanic and Atmospheric Administration)\n"]], ["block_12", [{"image_1": "462_1.png", "coords": [247, 133, 364, 231]}]], ["block_13", [" 9.4 \u2022 Effusion and Diffusion of Gases \n 449 \n"]]], "page_463": [["block_0", [" 450 \n 9 \u2022 Gases \n"]], ["block_1", ["If a mixture of gases is placed in a container with porous walls, the gases effuse through the small openings in\nthe walls. The lighter gases pass through the small openings more rapidly (at a higher rate) than the heavier\nones (Figure 9.29). In 1832, Thomas Graham studied the rates of effusion of different gases and formulated\n Graham\u2019s law of effusion : The rate of effusion of a gas is inversely proportional to the square root of the mass\nof its particles:\n"]], ["block_2", ["The lighter gas, H2, passes through the opening faster than O2, so just after the stopcock is opened, more H2\nmolecules move to the O2 side than O2 molecules move to the H2 side. (c) After a short time, both the slower-\nmoving O2 molecules and the faster-moving H2 molecules have distributed themselves evenly on both sides of the\nvessel.\n"]], ["block_3", ["We are often interested in the rate of diffusion , the amount of gas passing through some area per unit time:\n"]], ["block_4", ["The diffusion rate depends on several factors: the concentration gradient (the increase or decrease in\nconcentration from one point to another); the amount of surface area available for diffusion; and the distance\nthe gas particles must travel. Note also that the time required for diffusion to occur is inversely proportional to\nthe rate of diffusion, as shown in the rate of diffusion equation.\n"]], ["block_5", ["A process involving movement of gaseous species similar to diffusion is effusion , the escape of gas molecules\nthrough a tiny hole such as a pinhole in a balloon into a vacuum (Figure 9.28). Although diffusion and effusion\nrates both depend on the molar mass of the gas involved, their rates are not equal; however, the ratios of their\nrates are the same.\n"]], ["block_6", [{"image_0": "463_0.png", "coords": [72, 275, 540, 402]}]], ["block_7", [" FIGURE 9.28 \nDiffusion involves the unrestricted dispersal of molecules throughout space due to their random\n"]], ["block_8", ["motion. When this process is restricted to passage of molecules through very small openings in a physical barrier,\nthe process is called effusion.\n"]], ["block_9", ["This means that if two gases A and B are at the same temperature and pressure, the ratio of their effusion rates\nis inversely proportional to the ratio of the square roots of the masses of their particles:\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["\u2133\n"]], ["block_12", ["\u2133\n"]], ["block_13", ["\u2133\n"]]], "page_464": [["block_0", [" FIGURE 9.29 \nThe left photograph shows two balloons inflated with different gases, helium (orange) and argon\n"]], ["block_1", ["(blue).The right-side photograph shows the balloons approximately 12 hours after being filled, at which time the\nhelium balloon has become noticeably more deflated than the argon balloon, due to the greater effusion rate of the\nlighter helium gas. (credit: modification of work by Paul Flowers)\n"]], ["block_2", [" Applying Graham\u2019s Law to Rates of Effusion \n"]], ["block_3", ["Calculate the ratio of the rate of effusion of hydrogen to the rate of effusion of oxygen.\n"]], ["block_4", [" Solution \n"]], ["block_5", ["From Graham\u2019s law, we have:\n"]], ["block_6", ["Hydrogen effuses four times as rapidly as oxygen.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["At a particular pressure and temperature, nitrogen gas effuses at the rate of 79 mL/s. Under the same\nconditions, at what rate will sulfur dioxide effuse?\n"]], ["block_9", [" Answer: \n52 mL/s\n"]], ["block_10", [" Effusion Time Calculations \n"]], ["block_11", ["It takes 243 s for 4.46\n10mol Xe to effuse through a tiny hole. Under the same conditions, how long will it\n"]], ["block_12", ["take 4.46\n10mol Ne to effuse?\n"]], ["block_13", [" Solution \n"]], ["block_14", ["It is important to resist the temptation to use the times directly, and to remember how rate relates to time as\nwell as how it relates to mass. Recall the definition of rate of effusion:\n"]], ["block_15", ["and combine it with Graham\u2019s law:\n"]], ["block_16", ["EXAMPLE 9.20\n"]], ["block_17", ["EXAMPLE 9.21\n"]], ["block_18", [{"image_0": "464_0.png", "coords": [130, 57, 481, 166]}]], ["block_19", ["\u2133\n"]], ["block_20", ["\u2133\n"]], ["block_21", [" 9.4 \u2022 Effusion and Diffusion of Gases \n 451 \n"]]], "page_465": [["block_0", [" 452 \n 9 \u2022 Gases \n"]], ["block_1", ["To get:\n"]], ["block_2", ["Noting that amount of A = amount of B, and solving for time for Ne:\n"]], ["block_3", ["and substitute values:\n"]], ["block_4", ["Finally, solve for the desired quantity:\n"]], ["block_5", ["Note that this answer is reasonable: Since Ne is lighter than Xe, the effusion rate for Ne will be larger than that\nfor Xe, which means the time of effusion for Ne will be smaller than that for Xe.\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["A party balloon filled with helium deflates to\nof its original volume in 8.0 hours. How long will it take an\n"]], ["block_8", ["identical balloon filled with the same number of moles of air (\u2133 = 28.2 g/mol) to deflate to\nof its original\n"]], ["block_9", ["volume?\n"]], ["block_10", [" Answer: \n32 h\n"]], ["block_11", [" Determining Molar Mass Using Graham\u2019s Law \n"]], ["block_12", ["An unknown gas effuses 1.66 times more rapidly than CO2. What is the molar mass of the unknown gas? Can\nyou make a reasonable guess as to its identity?\n"]], ["block_13", [" Solution \n"]], ["block_14", ["From Graham\u2019s law, we have:\n"]], ["block_15", ["Plug in known data:\n"]], ["block_16", ["Solve:\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["EXAMPLE 9.22\n"]], ["block_19", ["\u2133\n"]], ["block_20", ["\u2133\n"]], ["block_21", ["\u2133\n"]], ["block_22", ["\u2133\n"]], ["block_23", ["\u2133\n"]], ["block_24", ["\u2133\n"]], ["block_25", ["\u2133\n"]], ["block_26", ["\u2133\n"]], ["block_27", ["\u2133\n"]], ["block_28", ["\u2133\n"]]], "page_466": [["block_0", ["The gas could well be CH4, the only gas with this molar mass.\n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["Hydrogen gas effuses through a porous container 8.97-times faster than an unknown gas. Estimate the molar\nmass of the unknown gas.\n"]], ["block_3", [" Answer: \n163 g/mol\n"]], ["block_4", [" Use of Diffusion for Nuclear Energy Applications: Uranium Enrichment \nGaseous diffusion has been used to produce enriched uranium for use in nuclear power plants and weapons.\nNaturally occurring uranium contains only 0.72% of U, the kind of uranium that is \u201cfissile,\u201d that is, capable\nof sustaining a nuclear fission chain reaction. Nuclear reactors require fuel that is 2\u20135% U, and nuclear\nbombs need even higher concentrations. One way to enrich uranium to the desired levels is to take advantage\nof Graham\u2019s law. In a gaseous diffusion enrichment plant, uranium hexafluoride (UF6, the only uranium\ncompound that is volatile enough to work) is slowly pumped through large cylindrical vessels called diffusers,\nwhich contain porous barriers with microscopic openings. The process is one of diffusion because the other\nside of the barrier is not evacuated. The UF6 molecules have a higher average speed and diffuse through the\nbarrier a little faster than the heavier UF6 molecules. The gas that has passed through the barrier is slightly\nenriched in UF6 and the residual gas is slightly depleted. The small difference in molecular weights between\n235UF6 and 238UF6 only about 0.4% enrichment, is achieved in one diffuser (Figure 9.30). But by connecting\nmany diffusers in a sequence of stages (called a cascade), the desired level of enrichment can be attained.\n"]], ["block_5", [" FIGURE 9.30 \nIn a diffuser, gaseous UF6 is pumped through a porous barrier, which partially separates UF6 from\n"]], ["block_6", ["238UF6 The UF6 must pass through many large diffuser units to achieve sufficient enrichment in 235U.\n"]], ["block_7", ["The large scale separation of gaseous UF6 from UF6 was first done during the World War II, at the atomic\nenergy installation in Oak Ridge, Tennessee, as part of the Manhattan Project (the development of the first\natomic bomb). Although the theory is simple, this required surmounting many daunting technical challenges\nto make it work in practice. The barrier must have tiny, uniform holes (about 10cm in diameter) and be\nporous enough to produce high flow rates. All materials (the barrier, tubing, surface coatings, lubricants, and\ngaskets) need to be able to contain, but not react with, the highly reactive and corrosive UF6.\n"]], ["block_8", ["Because gaseous diffusion plants require very large amounts of energy (to compress the gas to the high\n"]], ["block_9", [{"image_0": "466_0.png", "coords": [90, 375, 522, 585]}]], ["block_10", ["HOW SCIENCES INTERCONNECT\n"]], ["block_11", [" 9.4 \u2022 Effusion and Diffusion of Gases \n 453 \n"]]], "page_467": [["block_0", [" 454 \n 9 \u2022 Gases \n"]], ["block_1", ["pressures required and drive it through the diffuser cascade, to remove the heat produced during\ncompression, and so on), it is now being replaced by gas centrifuge technology, which requires far less energy.\nA current hot political issue is how to deny this technology to Iran, to prevent it from producing enough\nenriched uranium for them to use to make nuclear weapons.\n"]], ["block_2", [" 9.5 The Kinetic-Molecular Theory \n"]], ["block_3", [" LEARNING OBJECTIVES \n"]], ["block_4", ["The gas laws that we have seen to this point, as well as the ideal gas equation, are empirical, that is, they have\nbeen derived from experimental observations. The mathematical forms of these laws closely describe the\nmacroscopic behavior of most gases at pressures less than about 1 or 2 atm. Although the gas laws describe\nrelationships that have been verified by many experiments, they do not tell us why gases follow these\nrelationships.\n"]], ["block_5", ["The kinetic molecular theory (KMT) is a simple microscopic model that effectively explains the gas laws\ndescribed in previous modules of this chapter. This theory is based on the following five postulates described\nhere. (Note: The term \u201cmolecule\u201d will be used to refer to the individual chemical species that compose the gas,\nalthough some gases are composed of atomic species, for example, the noble gases.)\n"]], ["block_6", ["The test of the KMT and its postulates is its ability to explain and describe the behavior of a gas. The various\ngas laws can be derived from the assumptions of the KMT, which have led chemists to believe that the\nassumptions of the theory accurately represent the properties of gas molecules. We will first look at the\nindividual gas laws (Boyle\u2019s, Charles\u2019s, Amontons\u2019s, Avogadro\u2019s, and Dalton\u2019s laws) conceptually to see how the\nKMT explains them. Then, we will more carefully consider the relationships between molecular masses,\nspeeds, and kinetic energies with temperature, and explain Graham\u2019s law.\n"]], ["block_7", [" The Kinetic-Molecular Theory Explains the Behavior of Gases, Part I \n"]], ["block_8", ["Recalling that gas pressure is exerted by rapidly moving gas molecules and depends directly on the number of\nmolecules hitting a unit area of the wall per unit of time, we see that the KMT conceptually explains the\nbehavior of a gas as follows:\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["1.\nGases are composed of molecules that are in continuous motion, travelling in straight lines and changing\ndirection only when they collide with other molecules or with the walls of a container.\n"]], ["block_11", ["2.\nThe molecules composing the gas are negligibly small compared to the distances between them.\n"]], ["block_12", ["3.\nThe pressure exerted by a gas in a container results from collisions between the gas molecules and the\ncontainer walls.\n"]], ["block_13", ["4.\nGas molecules exert no attractive or repulsive forces on each other or the container walls; therefore, their\ncollisions are elastic (do not involve a loss of energy).\n"]], ["block_14", ["5.\nThe average kinetic energy of the gas molecules is proportional to the kelvin temperature of the gas.\n"]], ["block_15", ["\u2022\nAmontons\u2019s law. If the temperature is increased, the average speed and kinetic energy of the gas\nmolecules increase. If the volume is held constant, the increased speed of the gas molecules results in\nmore frequent and more forceful collisions with the walls of the container, therefore increasing the\npressure (Figure 9.31).\n"]], ["block_16", ["\u2022\nCharles\u2019s law. If the temperature of a gas is increased, a constant pressure may be maintained only if the\nvolume occupied by the gas increases. This will result in greater average distances traveled by the\nmolecules to reach the container walls, as well as increased wall surface area. These conditions will\ndecrease the both the frequency of molecule-wall collisions and the number of collisions per unit area, the\ncombined effects of which balance the effect of increased collision forces due to the greater kinetic energy\nat the higher temperature.\n"]], ["block_17", ["\u2022\nBoyle\u2019s law. If the gas volume volume of a given amount of gas at a given temperature is decreased (that is,\nif the gas is compressed), the molecules will be exposed to a decreased container wall area. Collisions with\n"]], ["block_18", ["\u2022\nState the postulates of the kinetic-molecular theory\n"]], ["block_19", ["\u2022\nUse this theory\u2019s postulates to explain the gas laws\n"]]], "page_468": [["block_0", [{"image_0": "468_0.png", "coords": [72, 177, 540, 407]}]], ["block_1", [" FIGURE 9.31 \n(a) When gas temperature increases, gas pressure increases due to increased force and frequency of\n"]], ["block_2", ["molecular collisions. (b) When volume decreases, gas pressure increases due to increased frequency of molecular\ncollisions. (c) When the amount of gas increases at a constant pressure, volume increases to yield a constant\nnumber of collisions per unit wall area per unit time.\n"]], ["block_3", [" molecular speeds and Kinetic Energy \n"]], ["block_4", ["The previous discussion showed that the KMT qualitatively explains the behaviors described by the various gas\nlaws. The postulates of this theory may be applied in a more quantitative fashion to derive these individual\nlaws. To do this, we must first look at speeds and kinetic energies of gas molecules, and the temperature of a\ngas sample.\n"]], ["block_5", ["In a gas sample, individual molecules have widely varying speeds; however, because of the vast number of\nmolecules and collisions involved, the molecular speed distribution and average speed are constant. This\nmolecular speed distribution is known as a Maxwell-Boltzmann distribution, and it depicts the relative\nnumbers of molecules in a bulk sample of gas that possesses a given speed (Figure 9.32).\n"]], ["block_6", ["\u2022\nAvogadro\u2019s law. At constant pressure and temperature, the frequency and force of molecule-wall collisions\nare constant. Under such conditions, increasing the number of gaseous molecules will require a\nproportional increase in the container volume in order to yield a decrease in the number of collisions per\nunit area to compensate for the increased frequency of collisions (Figure 9.31).\n"]], ["block_7", ["\u2022\nDalton\u2019s Law. Because of the large distances between them, the molecules of one gas in a mixture bombard\nthe container walls with the same frequency whether other gases are present or not, and the total pressure\nof a gas mixture equals the sum of the (partial) pressures of the individual gases.\n"]], ["block_8", ["the container wall will therefore occur more frequently and the pressure exerted by the gas will increase\n(Figure 9.31).\n"]], ["block_9", [" 9.5 \u2022 The Kinetic-Molecular Theory \n 455 \n"]]], "page_469": [["block_0", [" 456 \n 9 \u2022 Gases \n"]], ["block_1", [" FIGURE 9.32 \nThe molecular speed distribution for oxygen gas at 300 K is shown here. Very few molecules move at\n"]], ["block_2", ["either very low or very high speeds. The number of molecules with intermediate speeds increases rapidly up to a\nmaximum, which is the most probable speed, then drops off rapidly. Note that the most probable speed, \u03bdp, is a little\nless than 400 m/s, while the root mean square speed, urms, is closer to 500 m/s.\n"]], ["block_3", ["The kinetic energy (KE) of a particle of mass (m) and speed (u) is given by:\n"]], ["block_4", ["Expressing mass in kilograms and speed in meters per second will yield energy values in units of joules (J = kg\nms). To deal with a large number of gas molecules, we use averages for both speed and kinetic energy. In\nthe KMT, the root mean square speed of a particle, u rms , is defined as the square root of the average of the\nsquares of the speeds with n = the number of particles:\n"]], ["block_5", ["The average kinetic energy for a mole of particles, KEavg, is then equal to:\n"]], ["block_6", ["where M is the molar mass expressed in units of kg/mol. The KEavg of a mole of gas molecules is also directly\nproportional to the temperature of the gas and may be described by the equation:\n"]], ["block_7", ["where R is the gas constant and T is the kelvin temperature. When used in this equation, the appropriate form\nof the gas constant is 8.314 J/mol\u22c5K (8.314 kg msmolK). These two separate equations for KEavg may be\ncombined and rearranged to yield a relation between molecular speed and temperature:\n"]], ["block_8", [" Calculation of u rms \nCalculate the root-mean-square speed for a nitrogen molecule at 30 \u00b0C.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["EXAMPLE 9.23\n"]], ["block_11", [{"image_0": "469_0.png", "coords": [189, 57, 423, 241]}]]], "page_470": [["block_0", [" Solution \n"]], ["block_1", ["Convert the temperature into Kelvin:\n"]], ["block_2", ["Determine the molar mass of nitrogen in kilograms:\n"]], ["block_3", ["Replace the variables and constants in the root-mean-square speed equation, replacing Joules with the\nequivalent kg ms:\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["Calculate the root-mean-square speed for a mole of oxygen molecules at \u201323 \u00b0C.\n"]], ["block_6", [" Answer: \n441 m/s\n"]], ["block_7", ["If the temperature of a gas increases, its KEavg increases, more molecules have higher speeds and fewer\nmolecules have lower speeds, and the distribution shifts toward higher speeds overall, that is, to the right. If\ntemperature decreases, KEavg decreases, more molecules have lower speeds and fewer molecules have higher\nspeeds, and the distribution shifts toward lower speeds overall, that is, to the left. This behavior is illustrated\nfor nitrogen gas in Figure 9.33.\n"]], ["block_8", [" FIGURE 9.33 \nThe molecular speed distribution for nitrogen gas (N2) shifts to the right and flattens as the\n"]], ["block_9", ["temperature increases; it shifts to the left and heightens as the temperature decreases.\n"]], ["block_10", ["At a given temperature, all gases have the same KEavg for their molecules. Gases composed of lighter molecules\nhave more high-speed particles and a higher urms, with a speed distribution that peaks at relatively higher\nspeeds. Gases consisting of heavier molecules have more low-speed particles, a lower urms, and a speed\ndistribution that peaks at relatively lower speeds. This trend is demonstrated by the data for a series of noble\ngases shown in Figure 9.34.\n"]], ["block_11", [{"image_0": "470_0.png", "coords": [189, 414, 423, 598]}]], ["block_12", [" 9.5 \u2022 The Kinetic-Molecular Theory \n 457 \n"]]], "page_471": [["block_0", [" 458 \n 9 \u2022 Gases \n"]], ["block_1", [" FIGURE 9.34 \nmolecular speed is directly related to molecular mass. At a given temperature, lighter molecules\n"]], ["block_2", ["move faster on average than heavier molecules.\n"]], ["block_3", ["The gas simulator (http://openstax.org/l/16MolecVelocity) may be used to examine the effect of temperature on\nmolecular speeds. Examine the simulator\u2019s \u201cenergy histograms\u201d (molecular speed distributions) and \u201cspecies\ninformation\u201d (which gives average speed values) for molecules of different masses at various temperatures.\n"]], ["block_4", [" The Kinetic-Molecular Theory Explains the Behavior of Gases, Part II \n"]], ["block_5", ["According to Graham\u2019s law, the molecules of a gas are in rapid motion and the molecules themselves are small.\nThe average distance between the molecules of a gas is large compared to the size of the molecules. As a\nconsequence, gas molecules can move past each other easily and diffuse at relatively fast rates.\n"]], ["block_6", ["The rate of effusion of a gas depends directly on the (average) speed of its molecules:\n"]], ["block_7", ["Using this relation, and the equation relating molecular speed to mass, Graham\u2019s law may be easily derived as\nshown here:\n"]], ["block_8", ["The ratio of the rates of effusion is thus derived to be inversely proportional to the ratio of the square roots of\ntheir masses. This is the same relation observed experimentally and expressed as Graham\u2019s law.\n"]], ["block_9", [" 9.6 Non-Ideal Gas Behavior \n"]], ["block_10", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_11", ["Thus far, the ideal gas law, PV = nRT, has been applied to a variety of different types of problems, ranging from\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["\u2022\nDescribe the physical factors that lead to deviations from ideal gas behavior\n"]], ["block_14", ["\u2022\nExplain how these factors are represented in the van der Waals equation\n"]], ["block_15", ["\u2022\nDefine compressibility (Z) and describe how its variation with pressure reflects non-ideal behavior\n"]], ["block_16", ["\u2022\nQuantify non-ideal behavior by comparing computations of gas properties using the ideal gas law and the van\nder Waals equation\n"]], ["block_17", ["LINK TO LEARNING\n"]], ["block_18", [{"image_0": "471_0.png", "coords": [189, 57, 423, 196]}]]], "page_472": [["block_0", ["reaction stoichiometry and empirical and molecular formula problems to determining the density and molar\nmass of a gas. As mentioned in the previous modules of this chapter, however, the behavior of a gas is often\nnon-ideal, meaning that the observed relationships between its pressure, volume, and temperature are not\naccurately described by the gas laws. In this section, the reasons for these deviations from ideal gas behavior\nare considered.\n"]], ["block_1", ["One way in which the accuracy of PV = nRT can be judged is by comparing the actual volume of 1 mole of gas\n(its molar volume, Vm) to the molar volume of an ideal gas at the same temperature and pressure. This ratio is\ncalled the compressibility factor (Z) with:\n"]], ["block_2", ["Ideal gas behavior is therefore indicated when this ratio is equal to 1, and any deviation from 1 is an indication\nof non-ideal behavior. Figure 9.35 shows plots of Z over a large pressure range for several common gases.\n"]], ["block_3", [" FIGURE 9.35 \nA graph of the compressibility factor (Z) vs. pressure shows that gases can exhibit significant\n"]], ["block_4", ["deviations from the behavior predicted by the ideal gas law.\n"]], ["block_5", ["As is apparent from Figure 9.35, the ideal gas law does not describe gas behavior well at relatively high\npressures. To determine why this is, consider the differences between real gas properties and what is expected\nof a hypothetical ideal gas.\n"]], ["block_6", ["Particles of a hypothetical ideal gas have no significant volume and do not attract or repel each other. In\ngeneral, real gases approximate this behavior at relatively low pressures and high temperatures. However, at\nhigh pressures, the molecules of a gas are crowded closer together, and the amount of empty space between\nthe molecules is reduced. At these higher pressures, the volume of the gas molecules themselves becomes\nappreciable relative to the total volume occupied by the gas. The gas therefore becomes less compressible at\nthese high pressures, and although its volume continues to decrease with increasing pressure, this decrease is\nnot proportional as predicted by Boyle\u2019s law.\n"]], ["block_7", ["At relatively low pressures, gas molecules have practically no attraction for one another because they are (on\naverage) so far apart, and they behave almost like particles of an ideal gas. At higher pressures, however, the\nforce of attraction is also no longer insignificant. This force pulls the molecules a little closer together, slightly\ndecreasing the pressure (if the volume is constant) or decreasing the volume (at constant pressure) (Figure\n9.36). This change is more pronounced at low temperatures because the molecules have lower KE relative to\nthe attractive forces, and so they are less effective in overcoming these attractions after colliding with one\nanother.\n"]], ["block_8", [{"image_0": "472_0.png", "coords": [130, 236, 481, 469]}]], ["block_9", [" 9.6 \u2022 Non-Ideal Gas Behavior \n 459 \n"]]], "page_473": [["block_0", [" 460 \n 9 \u2022 Gases \n"]], ["block_1", [" FIGURE 9.36 \n(a) Attractions between gas molecules serve to decrease the gas volume at constant pressure\n"]], ["block_2", ["compared to an ideal gas whose molecules experience no attractive forces. (b) These attractive forces will decrease\nthe force of collisions between the molecules and container walls, therefore reducing the pressure exerted at\nconstant volume compared to an ideal gas.\n"]], ["block_3", ["There are several different equations that better approximate gas behavior than does the ideal gas law. The\nfirst, and simplest, of these was developed by the Dutch scientist Johannes van der Waals in 1879. The van der \n Waals equation improves upon the ideal gas law by adding two terms: one to account for the volume of the gas\nmolecules and another for the attractive forces between them.\n"]], ["block_4", [{"image_0": "473_0.png", "coords": [72, 322, 423, 392]}]], ["block_5", ["The constant a corresponds to the strength of the attraction between molecules of a particular gas, and the\nconstant b corresponds to the size of the molecules of a particular gas. The \u201ccorrection\u201d to the pressure term in\n"]], ["block_6", ["the ideal gas law is\nand the \u201ccorrection\u201d to the volume is nb. Note that when V is relatively large and n is\n"]], ["block_7", ["relatively small, both of these correction terms become negligible, and the van der Waals equation reduces to\nthe ideal gas law, PV = nRT. Such a condition corresponds to a gas in which a relatively low number of\nmolecules is occupying a relatively large volume, that is, a gas at a relatively low pressure. Experimental values\nfor the van der Waals constants of some common gases are given in Table 9.3.\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", [{"image_1": "473_1.png", "coords": [81, 57, 531, 206]}]], ["block_10", [" TABLE 9.3 \n"]], ["block_11", ["Values of van der Waals Constants for Some Common Gases\n"]], ["block_12", [" Gas \n a (L 2 atm/mol 2 ) \n b (L/mol) \n"]], ["block_13", ["N2\n1.39\n0.0391\n"]], ["block_14", ["O2\n1.36\n0.0318\n"]], ["block_15", ["CO2\n3.59\n0.0427\n"]], ["block_16", ["H2O\n5.46\n0.0305\n"]], ["block_17", ["He\n0.0342\n0.0237\n"]], ["block_18", ["CCl4\n20.4\n0.1383\n"]]], "page_474": [["block_0", ["At low pressures, the correction for intermolecular attraction, a, is more important than the one for molecular\nvolume, b. At high pressures and small volumes, the correction for the volume of the molecules becomes\nimportant because the molecules themselves are incompressible and constitute an appreciable fraction of the\ntotal volume. At some intermediate pressure, the two corrections have opposing influences and the gas\nappears to follow the relationship given by PV = nRT over a small range of pressures. This behavior is reflected\nby the \u201cdips\u201d in several of the compressibility curves shown in Figure 9.35. The attractive force between\nmolecules initially makes the gas more compressible than an ideal gas, as pressure is raised (Z decreases with\nincreasing P). At very high pressures, the gas becomes less compressible (Z increases with P), as the gas\nmolecules begin to occupy an increasingly significant fraction of the total gas volume.\n"]], ["block_1", ["Strictly speaking, the ideal gas equation functions well when intermolecular attractions between gas\nmolecules are negligible and the gas molecules themselves do not occupy an appreciable part of the whole\nvolume. These criteria are satisfied under conditions of low pressure and high temperature. Under such\nconditions, the gas is said to behave ideally, and deviations from the gas laws are small enough that they may\nbe disregarded\u2014this is, however, very often not the case.\n"]], ["block_2", [" Comparison of Ideal Gas Law and van der Waals Equation \n"]], ["block_3", ["A 4.25-L flask contains 3.46 mol CO2 at 229 \u00b0C. Calculate the pressure of this sample of CO2:\n"]], ["block_4", ["(a) from the ideal gas law\n"]], ["block_5", ["(b) from the van der Waals equation\n"]], ["block_6", ["(c) Explain the reason(s) for the difference.\n"]], ["block_7", [" Solution \n"]], ["block_8", ["(a) From the ideal gas law:\n"]], ["block_9", ["(b) From the van der Waals equation:\n"]], ["block_10", ["This finally yields P = 32.4 atm.\n"]], ["block_11", ["(c) This is not very different from the value from the ideal gas law because the pressure is not very high and the\ntemperature is not very low. The value is somewhat different because CO2 molecules do have some volume and\nattractions between molecules, and the ideal gas law assumes they do not have volume or attractions.\n"]], ["block_12", [" Check your Learning \n"]], ["block_13", ["A 560-mL flask contains 21.3 g N2 at 145 \u00b0C. Calculate the pressure of N2:\n"]], ["block_14", ["(a) from the ideal gas law\n"]], ["block_15", ["(b) from the van der Waals equation\n"]], ["block_16", ["(c) Explain the reason(s) for the difference.\n"]], ["block_17", [" Answer: \n(a) 46.562 atm; (b) 46.594 atm; (c) The van der Waals equation takes into account the volume of the gas\nmolecules themselves as well as intermolecular attractions.\n"]], ["block_18", ["EXAMPLE 9.24\n"]], ["block_19", [" 9.6 \u2022 Non-Ideal Gas Behavior \n 461 \n"]]], "page_475": [["block_0", [" 462 \n 9 \u2022 Key Terms \n"]], ["block_1", [" Key Terms \n"]], ["block_2", [" absolute zero \ntemperature at which the volume of\n"]], ["block_3", [" Amontons\u2019s law \n(also, Gay-Lussac\u2019s law) pressure\n"]], ["block_4", [" atmosphere (atm) \nunit of pressure; 1 atm =\n"]], ["block_5", [" Avogadro\u2019s law \nvolume of a gas at constant\n"]], ["block_6", [" bar \n( bar or b) unit of pressure; 1 bar = 100,000 Pa\n"]], ["block_7", [" barometer \ndevice used to measure atmospheric\n"]], ["block_8", [" Boyle\u2019s law \nvolume of a given number of moles of\n"]], ["block_9", [" Charles\u2019s law \nvolume of a given number of moles\n"]], ["block_10", [" compressibility factor (Z) \nratio of the\n"]], ["block_11", [" Dalton\u2019s law of partial pressures \ntotal pressure of\n"]], ["block_12", [" diffusion \nmovement of an atom or molecule from a\n"]], ["block_13", [" effusion \ntransfer of gaseous atoms or molecules\n"]], ["block_14", [" Graham\u2019s law of effusion \nrates of diffusion and\n"]], ["block_15", [" hydrostatic pressure \npressure exerted by a fluid\n"]], ["block_16", [" ideal gas \nhypothetical gas whose physical\n"]], ["block_17", [" Key Equations \n"]], ["block_18", [" Access for free at openstax.org \n"]], ["block_19", ["p = h\u03c1g\n"]], ["block_20", ["PV = nRT\n"]], ["block_21", ["PTotal = PA + PB + PC + \u2026 = \u01a9iPi\nPA = XA PTotal\n"]], ["block_22", ["a gas would be zero according to Charles\u2019s law.\n"]], ["block_23", ["of a given number of moles of gas is directly\nproportional to its kelvin temperature when the\nvolume is held constant\n"]], ["block_24", ["101,325 Pa\n"]], ["block_25", ["temperature and pressure is proportional to the\nnumber of gas molecules\n"]], ["block_26", [" pressure \n"]], ["block_27", ["gas held at constant temperature is inversely\nproportional to the pressure under which it is\nmeasured\n"]], ["block_28", ["of gas is directly proportional to its kelvin\ntemperature when the pressure is held constant\n"]], ["block_29", ["experimentally measured molar volume for a gas\nto its molar volume as computed from the ideal\ngas equation\n"]], ["block_30", ["a mixture of ideal gases is equal to the sum of the\npartial pressures of the component gases\n"]], ["block_31", ["region of relatively high concentration to one of\nrelatively low concentration (discussed in this\nchapter with regard to gaseous species, but\napplicable to species in any phase)\n"]], ["block_32", ["from a container to a vacuum through very small\nopenings\n"]], ["block_33", ["effusion of gases are inversely proportional to the\nsquare roots of their molecular masses\n"]], ["block_34", ["due to gravity\n"]], ["block_35", ["properties are perfectly described by the gas laws\n"]], ["block_36", [" ideal gas constant (R) \nconstant derived from the\n"]], ["block_37", [" ideal gas law \nrelation between the pressure,\n"]], ["block_38", [" kinetic molecular theory \ntheory based on simple\n"]], ["block_39", [" manometer \ndevice used to measure the pressure\n"]], ["block_40", [" mean free path \naverage distance a molecule\n"]], ["block_41", [" mole fraction (X) \nconcentration unit defined as the\n"]], ["block_42", [" partial pressure \npressure exerted by an individual\n"]], ["block_43", [" pascal (Pa) \nSI unit of pressure; 1 Pa = 1 N/m\n"]], ["block_44", [" pounds per square inch (psi) \nunit of pressure\n"]], ["block_45", [" pressure \nforce exerted per unit area\n"]], ["block_46", [" rate of diffusion \namount of gas diffusing through a\n"]], ["block_47", [" root mean square speed (u rms ) measure of average\n"]], ["block_48", [" standard conditions of temperature and pressure \n"]], ["block_49", [" standard molar volume \nvolume of 1 mole of gas at\n"]], ["block_50", [" torr \nunit of pressure;\n"]], ["block_51", [" van der Waals equation \nmodified version of the\n"]], ["block_52", [" vapor pressure of water \npressure exerted by\n"]], ["block_53", ["ideal gas equation R = 0.08206 L atm molKor\n8.314 L kPa molK\n"]], ["block_54", ["volume, amount, and temperature of a gas under\nconditions derived by combination of the simple\ngas laws\n"]], ["block_55", ["principles and assumptions that effectively\nexplains ideal gas behavior\n"]], ["block_56", ["of a gas trapped in a container\n"]], ["block_57", ["travels between collisions\n"]], ["block_58", ["ratio of the molar amount of a mixture\ncomponent to the total number of moles of all\nmixture components\n"]], ["block_59", ["gas in a mixture\n"]], ["block_60", ["common in the US\n"]], ["block_61", ["given area over a given time\n"]], ["block_62", ["speed for a group of particles calculated as the\nsquare root of the average squared speed\n"]], ["block_63", [" (STP) \n273.15 K (0 \u00b0C) and 1 atm (101.325 kPa)\n"]], ["block_64", ["STP, approximately 22.4 L for gases behaving\nideally\n"]], ["block_65", ["ideal gas equation containing additional terms to\naccount for non-ideal gas behavior\n"]], ["block_66", ["water vapor in equilibrium with liquid water in a\nclosed container at a specific temperature\n"]]], "page_476": [["block_0", [" Summary \n"]], ["block_1", [" 9.1 Gas Pressure \n"]], ["block_2", ["Gases exert pressure, which is force per unit area.\nThe pressure of a gas may be expressed in the SI\nunit of pascal or kilopascal, as well as in many other\nunits including torr, atmosphere, and bar.\nAtmospheric pressure is measured using a\nbarometer; other gas pressures can be measured\nusing one of several types of manometers.\n"]], ["block_3", [" 9.2 Relating Pressure, Volume, Amount, and \n Temperature: The Ideal Gas Law \n"]], ["block_4", ["The behavior of gases can be described by several\nlaws based on experimental observations of their\nproperties. The pressure of a given amount of gas is\ndirectly proportional to its absolute temperature,\nprovided that the volume does not change\n(Amontons\u2019s law). The volume of a given gas sample\nis directly proportional to its absolute temperature\nat constant pressure (Charles\u2019s law). The volume of a\ngiven amount of gas is inversely proportional to its\npressure when temperature is held constant (Boyle\u2019s\nlaw). Under the same conditions of temperature and\npressure, equal volumes of all gases contain the\nsame number of molecules (Avogadro\u2019s law).\n"]], ["block_5", ["The equations describing these laws are special\ncases of the ideal gas law, PV = nRT, where P is the\npressure of the gas, V is its volume, n is the number\nof moles of the gas, T is its kelvin temperature, and R\nis the ideal (universal) gas constant.\n"]], ["block_6", [" 9.3 Stoichiometry of Gaseous Substances, \n Mixtures, and Reactions \n"]], ["block_7", ["The ideal gas law can be used to derive a number of\nconvenient equations relating directly measured\n"]], ["block_8", ["\u2133\n"]], ["block_9", ["\u2133\n"]], ["block_10", ["quantities to properties of interest for gaseous\nsubstances and mixtures. Appropriate\nrearrangement of the ideal gas equation may be\nmade to permit the calculation of gas densities and\nmolar masses. Dalton\u2019s law of partial pressures may\nbe used to relate measured gas pressures for\ngaseous mixtures to their compositions. Avogadro\u2019s\nlaw may be used in stoichiometric computations for\nchemical reactions involving gaseous reactants or\nproducts.\n"]], ["block_11", [" 9.4 Effusion and Diffusion of Gases \n"]], ["block_12", ["Gaseous atoms and molecules move freely and\nrandomly through space. Diffusion is the process\nwhereby gaseous atoms and molecules are\ntransferred from regions of relatively high\nconcentration to regions of relatively low\nconcentration. Effusion is a similar process in which\ngaseous species pass from a container to a vacuum\nthrough very small orifices. The rates of effusion of\ngases are inversely proportional to the square roots\nof their densities or to the square roots of their\natoms/molecules\u2019 masses (Graham\u2019s law).\n"]], ["block_13", [" 9.5 The Kinetic-Molecular Theory \n"]], ["block_14", ["The kinetic molecular theory is a simple but very\neffective model that effectively explains ideal gas\nbehavior. The theory assumes that gases consist of\nwidely separated molecules of negligible volume\nthat are in constant motion, colliding elastically with\none another and the walls of their container with\naverage speeds determined by their absolute\ntemperatures. The individual molecules of a gas\nexhibit a range of speeds, the distribution of these\nspeeds being dependent on the temperature of the\n"]], ["block_15", [" 9 \u2022 Summary \n 463 \n"]]], "page_477": [["block_0", [" 464 \n 9 \u2022 Exercises \n"]], ["block_1", ["gas and the mass of its molecules.\n"]], ["block_2", [" 9.6 Non-Ideal Gas Behavior \n"]], ["block_3", ["Gas molecules possess a finite volume and\nexperience forces of attraction for one another.\nConsequently, gas behavior is not necessarily\ndescribed well by the ideal gas law. Under conditions\nof low pressure and high temperature, these factors\nare negligible, the ideal gas equation is an accurate\n"]], ["block_4", [" Exercises \n"]], ["block_5", [" 9.1 Gas Pressure \n"]], ["block_6", [" 10 . A medical laboratory catalog describes the pressure in a cylinder of a gas as 14.82 MPa. What is the\n"]], ["block_7", [" 11 . Consider this scenario and answer the following questions: On a mid-August day in the northeastern\n"]], ["block_8", [" 12 . Why is it necessary to use a nonvolatile liquid in a barometer or manometer?\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", [" 1 . Why are sharp knives more effective than dull knives? (Hint: Think about the definition of pressure.)\n 2 . Why do some small bridges have weight limits that depend on how many wheels or axles the crossing\n"]], ["block_11", [" 3 . Why should you roll or belly-crawl rather than walk across a thinly-frozen pond?\n 4 . A typical barometric pressure in Redding, California, is about 750 mm Hg. Calculate this pressure in atm\n"]], ["block_12", [" 5 . A typical barometric pressure in Denver, Colorado, is 615 mm Hg. What is this pressure in atmospheres\n"]], ["block_13", [" 6 . A typical barometric pressure in Kansas City is 740 torr. What is this pressure in atmospheres, in\n"]], ["block_14", [" 7 . Canadian tire pressure gauges are marked in units of kilopascals. What reading on such a gauge\n"]], ["block_15", [" 8 . During the Viking landings on Mars, the atmospheric pressure was determined to be on the average about\n"]], ["block_16", [" 9 . The pressure of the atmosphere on the surface of the planet Venus is about 88.8 atm. Compare that\n"]], ["block_17", ["vehicle has?\n"]], ["block_18", ["and kPa.\n"]], ["block_19", ["and kilopascals?\n"]], ["block_20", ["millimeters of mercury, and in kilopascals?\n"]], ["block_21", ["corresponds to 32 psi?\n"]], ["block_22", ["6.50 millibars (1 bar = 0.987 atm). What is that pressure in torr and kPa?\n"]], ["block_23", ["pressure in psi to the normal pressure on earth at sea level in psi.\n"]], ["block_24", ["pressure of this gas in atmospheres and torr?\n"]], ["block_25", ["United States, the following information appeared in the local newspaper: atmospheric pressure at sea\nlevel 29.97 in. Hg, 1013.9 mbar.\n(a) What was the pressure in kPa?\n(b) The pressure near the seacoast in the northeastern United States is usually reported near 30.0 in. Hg.\nDuring a hurricane, the pressure may fall to near 28.0 in. Hg. Calculate the drop in pressure in torr.\n"]], ["block_26", ["description of gas behavior, and the gas is said to\nexhibit ideal behavior. However, at lower\ntemperatures and higher pressures, corrections for\nmolecular volume and molecular attractions are\nrequired to account for finite molecular size and\nattractive forces. The van der Waals equation is a\nmodified version of the ideal gas law that can be\nused to account for the non-ideal behavior of gases\nunder these conditions.\n"]]], "page_478": [["block_0", [" 13 . The pressure of a sample of gas is measured at sea level with a closed-end manometer. The liquid in the\n"]], ["block_1", [" 14 . The pressure of a sample of gas is measured with an open-end manometer, partially shown to the right.\n"]], ["block_2", [" 15 . The pressure of a sample of gas is measured at sea level with an open-end mercury manometer. Assuming\n"]], ["block_3", ["manometer is mercury. Determine the pressure of the gas in:\n(a) torr\n(b) Pa\n(c) bar\n"]], ["block_4", [{"image_0": "478_0.png", "coords": [91, 120, 451, 262]}]], ["block_5", ["The liquid in the manometer is mercury. Assuming atmospheric pressure is 29.92 in. Hg, determine the\npressure of the gas in:\n(a) torr\n(b) Pa\n(c) bar\n"]], ["block_6", [{"image_1": "478_1.png", "coords": [91, 340, 208, 468]}]], ["block_7", ["atmospheric pressure is 760.0 mm Hg, determine the pressure of the gas in:\n(a) mm Hg\n(b) atm\n(c) kPa\n"]], ["block_8", [{"image_2": "478_2.png", "coords": [91, 534, 208, 662]}]], ["block_9", [" 9 \u2022 Exercises \n 465 \n"]]], "page_479": [["block_0", [" 466 \n 9 \u2022 Exercises \n"]], ["block_1", [" 16 . The pressure of a sample of gas is measured at sea level with an open-end mercury manometer. Assuming\n"]], ["block_2", [" 17 . How would the use of a volatile liquid affect the measurement of a gas using open-ended manometers vs.\n"]], ["block_3", [" 9.2 Relating Pressure, Volume, Amount, and Temperature: The Ideal Gas Law \n"]], ["block_4", [" 18 . Sometimes leaving a bicycle in the sun on a hot day will cause a blowout. Why?\n 19 . Explain how the volume of the bubbles exhausted by a scuba diver (Figure 9.16) change as they rise to the\n"]], ["block_5", [" 20 . One way to state Boyle\u2019s law is \u201cAll other things being equal, the pressure of a gas is inversely proportional\n"]], ["block_6", [" 21 . An alternate way to state Avogadro\u2019s law is \u201cAll other things being equal, the number of molecules in a gas\n"]], ["block_7", [" 22 . How would the graph in Figure 9.12 change if the number of moles of gas in the sample used to determine\n"]], ["block_8", [" 23 . How would the graph in Figure 9.13 change if the number of moles of gas in the sample used to determine\n"]], ["block_9", [" 24 . In addition to the data found in Figure 9.13, what other information do we need to find the mass of the\n"]], ["block_10", [" 25 . Determine the volume of 1 mol of CH4 gas at 150 K and 1 atm, using Figure 9.12.\n 26 . Determine the pressure of the gas in the syringe shown in Figure 9.13 when its volume is 12.5 mL, using:\n"]], ["block_11", [" 27 . A spray can is used until it is empty except for the propellant gas, which has a pressure of 1344 torr at 23\n"]], ["block_12", [" 28 . What is the temperature of an 11.2-L sample of carbon monoxide, CO, at 744 torr if it occupies 13.3 L at 55\n"]], ["block_13", [" 29 . A 2.50-L volume of hydrogen measured at \u2013196 \u00b0C is warmed to 100 \u00b0C. Calculate the volume of the gas at\n"]], ["block_14", [" 30 . A balloon inflated with three breaths of air has a volume of 1.7 L. At the same temperature and pressure,\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["atmospheric pressure is 760 mm Hg, determine the pressure of the gas in:\n(a) mm Hg\n(b) atm\n(c) kPa\n"]], ["block_17", [{"image_0": "479_0.png", "coords": [91, 120, 208, 248]}]], ["block_18", ["closed-end manometers?\n"]], ["block_19", ["surface, assuming that they remain intact.\n"]], ["block_20", ["to its volume.\u201d (a) What is the meaning of the term \u201cinversely proportional?\u201d (b) What are the \u201cother\nthings\u201d that must be equal?\n"]], ["block_21", ["is directly proportional to the volume of the gas.\u201d (a) What is the meaning of the term \u201cdirectly\nproportional?\u201d (b) What are the \u201cother things\u201d that must be equal?\n"]], ["block_22", ["the curve were doubled?\n"]], ["block_23", ["the curve were doubled?\n"]], ["block_24", ["sample of air used to determine the graph?\n"]], ["block_25", ["(a) the appropriate graph\n(b) Boyle\u2019s law\n"]], ["block_26", ["\u00b0C. If the can is thrown into a fire (T = 475 \u00b0C), what will be the pressure in the hot can?\n"]], ["block_27", ["\u00b0C and 744 torr?\n"]], ["block_28", ["the higher temperature, assuming no change in pressure.\n"]], ["block_29", ["what is the volume of the balloon if five more same-sized breaths are added to the balloon?\n"]]], "page_480": [["block_0", [" 31 . A weather balloon contains 8.80 moles of helium at a pressure of 0.992 atm and a temperature of 25 \u00b0C at\n"]], ["block_1", [" 32 . The volume of an automobile air bag was 66.8 L when inflated at 25 \u00b0C with 77.8 g of nitrogen gas. What\n"]], ["block_2", [" 33 . How many moles of gaseous boron trifluoride, BF3, are contained in a 4.3410-L bulb at 788.0 K if the\n"]], ["block_3", [" 34 . Iodine, I2, is a solid at room temperature but sublimes (converts from a solid into a gas) when warmed.\n"]], ["block_4", [" 35 . How many grams of gas are present in each of the following cases?\n"]], ["block_5", [" 36 . A high altitude balloon is filled with 1.41\n10L of hydrogen at a temperature of 21 \u00b0C and a pressure of\n"]], ["block_6", [" 37 . A cylinder of medical oxygen has a volume of 35.4 L, and contains O2 at a pressure of 151 atm and a\n"]], ["block_7", [" 38 . A large scuba tank (Figure 9.16) with a volume of 18 L is rated for a pressure of 220 bar. The tank is filled\n"]], ["block_8", [" 39 . A 20.0-L cylinder containing 11.34 kg of butane, C4H10, was opened to the atmosphere. Calculate the mass\n"]], ["block_9", [" 40 . While resting, the average 70-kg human male consumes 14 L of pure O2 per hour at 25 \u00b0C and 100 kPa.\n"]], ["block_10", [" 41 . For a given amount of gas showing ideal behavior, draw labeled graphs of:\n"]], ["block_11", [" 42 . A liter of methane gas, CH4, at STP contains more atoms of hydrogen than does a liter of pure hydrogen\n"]], ["block_12", [" 43 . The effect of chlorofluorocarbons (such as CCl2F2) on the depletion of the ozone layer is well known. The\n"]], ["block_13", [" 44 . As 1 g of the radioactive element radium decays over 1 year, it produces 1.16\n10alpha particles\n"]], ["block_14", [" 45 . A balloon with a volume of 100.21 L at 21 \u00b0C and 0.981 atm is released and just barely clears the top of\n"]], ["block_15", [" 46 . If the temperature of a fixed amount of a gas is doubled at constant volume, what happens to the pressure?\n 47 . If the volume of a fixed amount of a gas is tripled at constant temperature, what happens to the pressure?\n"]], ["block_16", ["ground level. What is the volume of the balloon under these conditions?\n"]], ["block_17", [{"image_0": "480_0.png", "coords": [91, 82, 208, 170]}]], ["block_18", ["was the pressure in the bag in kPa?\n"]], ["block_19", ["pressure is 1.220 atm? How many grams of BF3?\n"]], ["block_20", ["What is the temperature in a 73.3-mL bulb that contains 0.292 g of I2 vapor at a pressure of 0.462 atm?\n"]], ["block_21", ["(a) 0.100 L of CO2 at 307 torr and 26 \u00b0C\n(b) 8.75 L of C2H4, at 378.3 kPa and 483 K\n(c) 221 mL of Ar at 0.23 torr and \u201354 \u00b0C\n"]], ["block_22", ["745 torr. What is the volume of the balloon at a height of 20 km, where the temperature is \u201348 \u00b0C and the\npressure is 63.1 torr?\n"]], ["block_23", ["temperature of 25 \u00b0C. What volume of O2 does this correspond to at normal body conditions, that is, 1 atm\nand 37 \u00b0C?\n"]], ["block_24", ["at 20 \u00b0C and contains enough air to supply 1860 L of air to a diver at a pressure of 2.37 atm (a depth of 45\nfeet). Was the tank filled to capacity at 20 \u00b0C?\n"]], ["block_25", ["of the gas remaining in the cylinder if it were opened and the gas escaped until the pressure in the\ncylinder was equal to the atmospheric pressure, 0.983 atm, and a temperature of 27 \u00b0C.\n"]], ["block_26", ["How many moles of O2 are consumed by a 70 kg man while resting for 1.0 h?\n"]], ["block_27", ["(a) the variation of P with V\n(b) the variation of V with T\n(c) the variation of P with T\n(d) the variation of\nwith V\n"]], ["block_28", ["gas, H2, at STP. Using Avogadro\u2019s law as a starting point, explain why.\n"]], ["block_29", ["use of substitutes, such as CH3CH2F(g), for the chlorofluorocarbons, has largely corrected the problem.\nCalculate the volume occupied by 10.0 g of each of these compounds at STP:\n(a) CCl2F2(g)\n(b) CH3CH2F(g)\n"]], ["block_30", ["(helium nuclei). Each alpha particle becomes an atom of helium gas. What is the pressure in pascal of the\nhelium gas produced if it occupies a volume of 125 mL at a temperature of 25 \u00b0C?\n"]], ["block_31", ["Mount Crumpit in British Columbia. If the final volume of the balloon is 144.53 L at a temperature of 5.24\n\u00b0C, what is the pressure experienced by the balloon as it clears Mount Crumpet?\n"]], ["block_32", [" 9 \u2022 Exercises \n 467 \n"]]], "page_481": [["block_0", [" 468 \n 9 \u2022 Exercises \n"]], ["block_1", [" 9.3 Stoichiometry of Gaseous Substances, Mixtures, and Reactions \n"]], ["block_2", [" 48 . What is the density of laughing gas, dinitrogen monoxide, N2O, at a temperature of 325 K and a pressure of\n"]], ["block_3", [" 49 . Calculate the density of Freon 12, CF2Cl2, at 30.0 \u00b0C and 0.954 atm.\n 50 . Which is denser at the same temperature and pressure, dry air or air saturated with water vapor? Explain.\n 51 . A cylinder of O2(g) used in breathing by patients with emphysema has a volume of 3.00 L at a pressure of\n"]], ["block_4", [" 52 . What is the molar mass of a gas if 0.0494 g of the gas occupies a volume of 0.100 L at a temperature 26 \u00b0C\n"]], ["block_5", [" 53 . What is the molar mass of a gas if 0.281 g of the gas occupies a volume of 125 mL at a temperature 126 \u00b0C\n"]], ["block_6", [" 54 . How could you show experimentally that the molecular formula of propene is C3H6, not CH2?\n 55 . The density of a certain gaseous fluoride of phosphorus is 3.93 g/L at STP. Calculate the molar mass of this\n"]], ["block_7", [" 56 . Consider this question: What is the molecular formula of a compound that contains 39% C, 45% N, and\n"]], ["block_8", [" 57 . A 36.0\u2013L cylinder of a gas used for calibration of blood gas analyzers in medical laboratories contains 350\n"]], ["block_9", [" 58 . A cylinder of a gas mixture used for calibration of blood gas analyzers in medical laboratories contains\n"]], ["block_10", [" 59 . A sample of gas isolated from unrefined petroleum contains 90.0% CH4, 8.9% C2H6, and 1.1% C3H8 at a\n"]], ["block_11", [" 60 . A mixture of 0.200 g of H2, 1.00 g of N2, and 0.820 g of Ar is stored in a closed container at STP. Find the\n"]], ["block_12", [" 61 . Most mixtures of hydrogen gas with oxygen gas are explosive. However, a mixture that contains less than\n"]], ["block_13", [" 62 . A commercial mercury vapor analyzer can detect, in air, concentrations of gaseous Hg atoms (which are\n"]], ["block_14", [" 63 . A sample of carbon monoxide was collected over water at a total pressure of 756 torr and a temperature of\n"]], ["block_15", [" 64 . In an experiment in a general chemistry laboratory, a student collected a sample of a gas over water. The\n"]], ["block_16", [" 65 . Joseph Priestley first prepared pure oxygen by heating mercuric oxide, HgO:\n"]], ["block_17", [" 66 . Cavendish prepared hydrogen in 1766 by the novel method of passing steam through a red-hot gun\n"]], ["block_18", [" Access for free at openstax.org \n"]], ["block_19", ["113.0 kPa?\n"]], ["block_20", ["10.0 atm. If the temperature of the cylinder is 28.0 \u00b0C, what mass of oxygen is in the cylinder?\n"]], ["block_21", ["and a pressure of 307 torr?\n"]], ["block_22", ["and a pressure of 777 torr?\n"]], ["block_23", ["fluoride and determine its molecular formula.\n"]], ["block_24", ["16% H if 0.157 g of the compound occupies l25 mL with a pressure of 99.5 kPa at 22 \u00b0C?\n(a) Outline the steps necessary to answer the question.\n(b) Answer the question.\n"]], ["block_25", ["g CO2, 805 g O2, and 4,880 g N2. At 25 degrees C, what is the pressure in the cylinder in atmospheres?\n"]], ["block_26", ["5.0% CO2, 12.0% O2, and the remainder N2 at a total pressure of 146 atm. What is the partial pressure of\neach component of this gas? (The percentages given indicate the percent of the total pressure that is due\nto each component.)\n"]], ["block_27", ["total pressure of 307.2 kPa. What is the partial pressure of each component of this gas? (The percentages\ngiven indicate the percent of the total pressure that is due to each component.)\n"]], ["block_28", ["volume of the container, assuming that the gases exhibit ideal behavior.\n"]], ["block_29", ["3.0 % O2 is not. If enough O2 is added to a cylinder of H2 at 33.2 atm to bring the total pressure to 34.5 atm,\nis the mixture explosive?\n"]], ["block_30", ["poisonous) as low as 2\n10mg/L of air. At this concentration, what is the partial pressure of gaseous\n"]], ["block_31", ["mercury if the atmospheric pressure is 733 torr at 26 \u00b0C?\n"]], ["block_32", ["18 \u00b0C. What is the pressure of the carbon monoxide? (See Table 9.2 for the vapor pressure of water.)\n"]], ["block_33", ["volume of the gas was 265 mL at a pressure of 753 torr and a temperature of 27 \u00b0C. The mass of the gas\nwas 0.472 g. What was the molar mass of the gas?\n"]], ["block_34", ["(a) Outline the steps necessary to answer the following question: What volume of O2 at 23 \u00b0C and 0.975\natm is produced by the decomposition of 5.36 g of HgO?\n(b) Answer the question.\n"]], ["block_35", ["barrel:\n"]], ["block_36", ["(a) Outline the steps necessary to answer the following question: What volume of H2 at a pressure of 745\ntorr and a temperature of 20 \u00b0C can be prepared from the reaction of 15.O g of H2O?\n(b) Answer the question.\n"]]], "page_482": [["block_0", [" 67 . The chlorofluorocarbon CCl2F2 can be recycled into a different compound by reaction with hydrogen to\n"]], ["block_1", [" 68 . Automobile air bags are inflated with nitrogen gas, which is formed by the decomposition of solid sodium\n"]], ["block_2", [" 69 . Lime, CaO, is produced by heating calcium carbonate, CaCO3; carbon dioxide is the other product.\n"]], ["block_3", [" 70 . Before small batteries were available, carbide lamps were used for bicycle lights. Acetylene gas, C2H2, and\n"]], ["block_4", [" 71 . Calculate the volume of oxygen required to burn 12.00 L of ethane gas, C2H6, to produce carbon dioxide\n"]], ["block_5", [" 72 . What volume of O2 at STP is required to oxidize 8.0 L of NO at STP to NO2? What volume of NO2 is\n"]], ["block_6", [" 73 . Consider the following questions:\n"]], ["block_7", [" 74 . Methanol, CH3OH, is produced industrially by the following reaction:\n"]], ["block_8", [" 75 . What volume of oxygen at 423.0 K and a pressure of 127.4 kPa is produced by the decomposition of 129.7\n"]], ["block_9", [" 76 . A 2.50-L sample of a colorless gas at STP decomposed to give 2.50 L of N2 and 1.25 L of O2 at STP. What is\n"]], ["block_10", [" 77 . Ethanol, C2H5OH, is produced industrially from ethylene, C2H4, by the following sequence of reactions:\n"]], ["block_11", [" 78 . One molecule of hemoglobin will combine with four molecules of oxygen. If 1.0 g of hemoglobin combines\n"]], ["block_12", [" 79 . A sample of a compound of xenon and fluorine was confined in a bulb with a pressure of 18 torr. Hydrogen\n"]], ["block_13", ["produce CH2F2(g), a compound useful in chemical manufacturing:\n"]], ["block_14", ["(a) Outline the steps necessary to answer the following question: What volume of hydrogen at 225 atm and\n35.5 \u00b0C would be required to react with 1 ton (1.000\n10kg) of CCl2F2?\n"]], ["block_15", ["(b) Answer the question.\n"]], ["block_16", ["azide (NaN3). The other product is sodium metal. Calculate the volume of nitrogen gas at 27 \u00b0C and 756\ntorr formed by the decomposition of 125 g of sodium azide.\n"]], ["block_17", ["(a) Outline the steps necessary to answer the following question: What volume of carbon dioxide at 875 K\nand 0.966 atm is produced by the decomposition of 1 ton (1.000\n10kg) of calcium carbonate?\n"]], ["block_18", ["(b) Answer the question.\n"]], ["block_19", ["solid calcium hydroxide were formed by the reaction of calcium carbide, CaC2, with water. The ignition of\nthe acetylene gas provided the light. Currently, the same lamps are used by some cavers, and calcium\ncarbide is used to produce acetylene for carbide cannons.\n(a) Outline the steps necessary to answer the following question: What volume of C2H2 at 1.005 atm and\n12.2 \u00b0C is formed by the reaction of 15.48 g of CaC2 with water?\n(b) Answer the question.\n"]], ["block_20", ["and water, if the volumes of C2H6 and O2 are measured under the same conditions of temperature and\npressure.\n"]], ["block_21", ["produced at STP?\n"]], ["block_22", ["(a) What is the total volume of the CO2(g) and H2O(g) at 600 \u00b0C and 0.888 atm produced by the combustion\nof 1.00 L of C2H6(g) measured at STP?\n(b) What is the partial pressure of H2O in the product gases?\n"]], ["block_23", ["Assuming that the gases behave as ideal gases, find the ratio of the total volume of the reactants to the\nfinal volume.\n"]], ["block_24", ["g of BaO2 to BaO and O2?\n"]], ["block_25", ["the colorless gas?\n"]], ["block_26", ["What volume of ethylene at STP is required to produce 1.000 metric ton (1000 kg) of ethanol if the overall\nyield of ethanol is 90.1%?\n"]], ["block_27", ["with 1.53 mL of oxygen at body temperature (37 \u00b0C) and a pressure of 743 torr, what is the molar mass of\nhemoglobin?\n"]], ["block_28", ["was added to the bulb until the pressure was 72 torr. Passage of an electric spark through the mixture\nproduced Xe and HF. After the HF was removed by reaction with solid KOH, the final pressure of xenon\nand unreacted hydrogen in the bulb was 36 torr. What is the empirical formula of the xenon fluoride in the\noriginal sample? (Note: Xenon fluorides contain only one xenon atom per molecule.)\n"]], ["block_29", [" 9 \u2022 Exercises \n 469 \n"]]], "page_483": [["block_0", [" 470 \n 9 \u2022 Exercises \n"]], ["block_1", [" 80 . One method of analyzing amino acids is the van Slyke method. The characteristic amino groups (\u2212NH2) in\n"]], ["block_2", [" 9.4 Effusion and Diffusion of Gases \n"]], ["block_3", [" 81 . A balloon filled with helium gas takes 6 hours to deflate to 50% of its original volume. How long will it take\n"]], ["block_4", [" 82 . Explain why the numbers of molecules are not identical in the left- and right-hand bulbs shown in the\n"]], ["block_5", [" 83 . Starting with the definition of rate of effusion and Graham\u2019s finding relating rate and molar mass, show\n"]], ["block_6", [" 84 . Heavy water, D2O (molar mass = 20.03 g mol), can be separated from ordinary water, H2O (molar mass =\n"]], ["block_7", [" 85 . Which of the following gases diffuse more slowly than oxygen? F2, Ne, N2O, C2H2, NO, Cl2, H2S\n 86 . During the discussion of gaseous diffusion for enriching uranium, it was claimed that UF6 diffuses\n"]], ["block_8", [" 87 . Calculate the relative rate of diffusion of H2 (molar mass 2.0 g/mol) compared with H2 (molar mass 4.0\n"]], ["block_9", [" 88 . A gas of unknown identity diffuses at a rate of 83.3 mL/s in a diffusion apparatus in which carbon dioxide\n"]], ["block_10", [" 89 . When two cotton plugs, one moistened with ammonia and the other with hydrochloric acid, are\n"]], ["block_11", [" 9.5 The Kinetic-Molecular Theory \n"]], ["block_12", [" 90 . Using the postulates of the kinetic molecular theory, explain why a gas uniformly fills a container of any\n"]], ["block_13", [" 91 . Can the speed of a given molecule in a gas double at constant temperature? Explain your answer.\n 92 . Describe what happens to the average kinetic energy of ideal gas molecules when the conditions are\n"]], ["block_14", [" 93 . The distribution of molecular speeds in a sample of helium is shown in Figure 9.34. If the sample is\n"]], ["block_15", [" 94 . What is the ratio of the average kinetic energy of a SO2 molecule to that of an O2 molecule in a mixture of\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["protein material are allowed to react with nitrous acid, HNO2, to form N2 gas. From the volume of the gas,\nthe amount of amino acid can be determined. A 0.0604-g sample of a biological sample containing\nglycine, CH2(NH2)COOH, was analyzed by the van Slyke method and yielded 3.70 mL of N2 collected over\nwater at a pressure of 735 torr and 29 \u00b0C. What was the percentage of glycine in the sample?\n"]], ["block_18", ["for an identical balloon filled with the same volume of hydrogen gas (instead of helium) to decrease its\nvolume by 50%?\n"]], ["block_19", ["center illustration of Figure 9.27.\n"]], ["block_20", ["how to derive the Graham\u2019s law equation, relating the relative rates of effusion for two gases to their\nmolecular masses.\n"]], ["block_21", ["18.01), as a result of the difference in the relative rates of diffusion of the molecules in the gas phase.\nCalculate the relative rates of diffusion of H2O and D2O.\n"]], ["block_22", ["0.4% faster than UF6. Show the calculation that supports this value. The molar mass of UF6 =\n235.043930 + 6\n18.998403 = 349.034348 g/mol, and the molar mass of UF6 = 238.050788 + 6\n"]], ["block_23", ["18.998403 = 352.041206 g/mol.\n"]], ["block_24", ["g/mol) and the relative rate of diffusion of O2 (molar mass 32 g/mol) compared with O3 (molar mass 48 g/\nmol).\n"]], ["block_25", ["diffuses at the rate of 102 mL/s. Calculate the molecular mass of the unknown gas.\n"]], ["block_26", ["simultaneously inserted into opposite ends of a glass tube that is 87.0 cm long, a white ring of NH4Cl\nforms where gaseous NH3 and gaseous HCl first come into contact.\nAt\n"]], ["block_27", ["approximately what distance from the ammonia moistened plug does this occur? (Hint: Calculate the rates\nof diffusion for both NH3 and HCl, and find out how much faster NH3 diffuses than HCl.)\n"]], ["block_28", ["shape.\n"]], ["block_29", ["changed as follows:\n(a) The pressure of the gas is increased by reducing the volume at constant temperature.\n(b) The pressure of the gas is increased by increasing the temperature at constant volume.\n(c) The average speed of the molecules is increased by a factor of 2.\n"]], ["block_30", ["cooled, will the distribution of speeds look more like that of H2 or of H2O? Explain your answer.\n"]], ["block_31", ["two gases? What is the ratio of the root mean square speeds, urms, of the two gases?\n"]]], "page_484": [["block_0", [" 95 . A 1-L sample of CO initially at STP is heated to 546 K, and its volume is increased to 2 L.\n"]], ["block_1", [" 96 . The root mean square speed of H2 molecules at 25 \u00b0C is about 1.6 km/s. What is the root mean square\n"]], ["block_2", [" 97 . Answer the following questions:\n"]], ["block_3", [" 98 . Show that the ratio of the rate of diffusion of Gas 1 to the rate of diffusion of Gas 2,\nis the same at 0 \u00b0C\n"]], ["block_4", ["(a) What effect do these changes have on the number of collisions of the molecules of the gas per unit area\nof the container wall?\n(b) What is the effect on the average kinetic energy of the molecules?\n(c) What is the effect on the root mean square speed of the molecules?\n"]], ["block_5", ["speed of a N2 molecule at 25 \u00b0C?\n"]], ["block_6", ["(a) Is the pressure of the gas in the hot-air balloon shown at the opening of this chapter greater than, less\nthan, or equal to that of the atmosphere outside the balloon?\n(b) Is the density of the gas in the hot-air balloon shown at the opening of this chapter greater than, less\nthan, or equal to that of the atmosphere outside the balloon?\n(c) At a pressure of 1 atm and a temperature of 20 \u00b0C, dry air has a density of 1.2256 g/L. What is the\n(average) molar mass of dry air?\n(d) The average temperature of the gas in a hot-air balloon is 1.30\n10\u00b0F. Calculate its density, assuming\n"]], ["block_7", ["the molar mass equals that of dry air.\n(e) The lifting capacity of a hot-air balloon is equal to the difference in the mass of the cool air displaced by\nthe balloon and the mass of the gas in the balloon. What is the difference in the mass of 1.00 L of the cool\nair in part (c) and the hot air in part (d)?\n(f) An average balloon has a diameter of 60 feet and a volume of 1.1\n10ft. What is the lifting power of\n"]], ["block_8", ["such a balloon? If the weight of the balloon and its rigging is 500 pounds, what is its capacity for carrying\npassengers and cargo?\n(g) A balloon carries 40.0 gallons of liquid propane (density 0.5005 g/L). What volume of CO2 and H2O gas\nis produced by the combustion of this propane?\n(h) A balloon flight can last about 90 minutes. If all of the fuel is burned during this time, what is the\napproximate rate of heat loss (in kJ/min) from the hot air in the bag during the flight?\n"]], ["block_9", ["and 100 \u00b0C.\n"]], ["block_10", [" 9 \u2022 Exercises \n 471 \n"]]], "page_485": [["block_0", [" 472 \n 9 \u2022 Exercises \n"]], ["block_1", [" 9.6 Non-Ideal Gas Behavior \n"]], ["block_2", [" 99 . Graphs showing the behavior of several different gases follow. Which of these gases exhibit behavior\n"]], ["block_3", [" Access for free at openstax.org \n"]], ["block_4", ["significantly different from that expected for ideal gases?\n"]], ["block_5", [{"image_0": "485_0.png", "coords": [91, 102, 524, 602]}]]], "page_486": [["block_0", [" 100 . Explain why the plot of PV for CO2 differs from that of an ideal gas.\n"]], ["block_1", [" 101 . Under which of the following sets of conditions does a real gas behave most like an ideal gas, and for\n"]], ["block_2", [" 102 . Describe the factors responsible for the deviation of the behavior of real gases from that of an\n"]], ["block_3", [" 103 . For which of the following gases should the correction for the molecular volume be largest:\n"]], ["block_4", [" 104 . A 0.245-L flask contains 0.467 mol CO2 at 159 \u00b0C. Calculate the pressure:\n"]], ["block_5", [" 105 . Answer the following questions:\n"]], ["block_6", [{"image_0": "486_0.png", "coords": [96, 70, 330, 266]}]], ["block_7", ["which conditions is a real gas expected to deviate from ideal behavior? Explain.\n(a) high pressure, small volume\n(b) high temperature, low pressure\n(c) low temperature, high pressure\n"]], ["block_8", ["ideal gas.\n"]], ["block_9", ["CO, CO2, H2, He, NH3, SF6?\n"]], ["block_10", ["(a) using the ideal gas law\n(b) using the van der Waals equation\n(c) Explain the reason for the difference.\n(d) Identify which correction (that for P or V) is dominant and why.\n"]], ["block_11", ["(a) If XX behaved as an ideal gas, what would its graph of Z vs. P look like?\n(b) For most of this chapter, we performed calculations treating gases as ideal. Was this justified?\n(c) What is the effect of the volume of gas molecules on Z? Under what conditions is this effect small?\nWhen is it large? Explain using an appropriate diagram.\n(d) What is the effect of intermolecular attractions on the value of Z? Under what conditions is this effect\nsmall? When is it large? Explain using an appropriate diagram.\n(e) In general, under what temperature conditions would you expect Z to have the largest deviations from\nthe Z for an ideal gas?\n"]], ["block_12", [" 9 \u2022 Exercises \n 473 \n"]]], "page_487": [["block_0", [" 474 \n 9 \u2022 Exercises \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_488": [["block_0", ["CHAPTER 10\nLiquids and Solids\n"]], ["block_1", [{"image_0": "488_0.png", "coords": [72, 104, 622, 326]}]], ["block_2", [" Figure 10.1 \nSolid carbon dioxide (\u201cdry ice\u201d, left) sublimes vigorously when placed in a liquid (right), cooling the\n"]], ["block_3", ["liquid and generating a dense mist of water above the cylinder. (credit: modification of work by Paul Flowers)\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 10.1 Intermolecular Forces \n 10.2 Properties of Liquids \n 10.3 Phase Transitions \n 10.4 Phase Diagrams \n 10.5 The Solid State of Matter \n 10.6 Lattice Structures in Crystalline Solids \n"]], ["block_6", [" INTRODUCTION \n"]], ["block_7", ["symptoms and complications of the illness, its social stigma led sufferers to be cast out of communities and\nisolated in colonies; in some regions this practice lasted well into the twentieth century. At that time, the best\npotential treatment for leprosy was oil from the chaulmoogra tree, but the oil was extremely thick, causing\nblisters and making usage painful and ineffective. Healthcare professionals seeking a better application\ncontacted Alice Ball, a young chemist at the University of Hawaii, who had focused her masters thesis on a\nsimilar plant. Ball initiated a sequence of procedures (repeated acidification and purification to change the\ncharacteristics of the oil and isolate the active substances (esters, discussed later in this text). The \"Ball\nMethod\" as it later came to be called, became the standard treatment for leprosy for decades. In the liquid and\nsolid states, atomic and molecular interactions are of considerable strength and play an important role in\ndetermining a number of physical properties of the substance. For example, the thickness, or viscosity, of the\nchaulmoogra oil was due to its intermolecular forces. In this chapter, the nature of these interactions and their\neffects on various physical properties of liquid and solid phases will be examined.\n"]], ["block_8", ["Leprosy has been a devastating disease throughout much of human history. Aside from the\n"]]], "page_489": [["block_0", [" 476 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [" 10.1 Intermolecular Forces \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["As was the case for gaseous substances, the kinetic molecular theory may be used to explain the behavior of\nsolids and liquids. In the following description, the term particle will be used to refer to an atom, molecule, or\nion. Note that we will use the popular phrase \u201cintermolecular attraction\u201d to refer to attractive forces between\nthe particles of a substance, regardless of whether these particles are molecules, atoms, or ions.\n"]], ["block_4", ["Consider these two aspects of the molecular-level environments in solid, liquid, and gaseous matter:\n"]], ["block_5", ["The differences in the properties of a solid, liquid, or gas reflect the strengths of the attractive forces between\nthe atoms, molecules, or ions that make up each phase. The phase in which a substance exists depends on the\nrelative extents of its intermolecular forces (IMFs) and the kinetic energies (KE) of its molecules. IMFs are the\nvarious forces of attraction that may exist between the atoms and molecules of a substance due to electrostatic\nphenomena, as will be detailed in this module. These forces serve to hold particles close together, whereas the\nparticles\u2019 KE provides the energy required to overcome the attractive forces and thus increase the distance\nbetween particles. Figure 10.2 illustrates how changes in physical state may be induced by changing the\ntemperature, hence, the average KE, of a given substance.\n"]], ["block_6", [" FIGURE 10.2 \nTransitions between solid, liquid, and gaseous states of a substance occur when conditions of\n"]], ["block_7", ["temperature or pressure favor the associated changes in intermolecular forces. (Note: The space between particles\nin the gas phase is much greater than shown.)\n"]], ["block_8", ["As an example of the processes depicted in this figure, consider a sample of water. When gaseous water is\ncooled sufficiently, the attractions between H2O molecules will be capable of holding them together when they\ncome into contact with each other; the gas condenses, forming liquid H2O. For example, liquid water forms on\nthe outside of a cold glass as the water vapor in the air is cooled by the cold glass, as seen in Figure 10.3.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["\u2022\nParticles in a solid are tightly packed together and often arranged in a regular pattern; in a liquid, they are\nclose together with no regular arrangement; in a gas, they are far apart with no regular arrangement.\n"]], ["block_11", ["\u2022\nParticles in a solid vibrate about fixed positions and do not generally move in relation to one another; in a\nliquid, they move past each other but remain in essentially constant contact; in a gas, they move\nindependently of one another except when they collide.\n"]], ["block_12", ["\u2022\nDescribe the types of intermolecular forces possible between atoms or molecules in condensed phases\n(dispersion forces, dipole-dipole attractions, and hydrogen bonding)\n"]], ["block_13", ["\u2022\nIdentify the types of intermolecular forces experienced by specific molecules based on their structures\n"]], ["block_14", ["\u2022\nExplain the relation between the intermolecular forces present within a substance and the temperatures\nassociated with changes in its physical state\n"]], ["block_15", [{"image_0": "489_0.png", "coords": [126, 430, 486, 634]}]]], "page_490": [["block_0", [" FIGURE 10.3 \nCondensation forms when water vapor in the air is cooled enough to form liquid water, such as (a) on\n"]], ["block_1", ["the outside of a cold beverage glass or (b) in the form of fog. (credit a: modification of work by Jenny Downing; credit\nb: modification of work by Cory Zanker)\n"]], ["block_2", ["We can also liquefy many gases by compressing them, if the temperature is not too high. The increased\npressure brings the molecules of a gas closer together, such that the attractions between the molecules become\nstrong relative to their KE. Consequently, they form liquids. Butane, C4H10, is the fuel used in disposable\nlighters and is a gas at standard temperature and pressure. Inside the lighter\u2019s fuel compartment, the butane is\ncompressed to a pressure that results in its condensation to the liquid state, as shown in Figure 10.4.\n"]], ["block_3", [" FIGURE 10.4 \nGaseous butane is compressed within the storage compartment of a disposable lighter, resulting in\n"]], ["block_4", ["its condensation to the liquid state. (credit: modification of work by \u201cSam-Cat\u201d/Flickr)\n"]], ["block_5", ["Finally, if the temperature of a liquid becomes sufficiently low, or the pressure on the liquid becomes\nsufficiently high, the molecules of the liquid no longer have enough KE to overcome the IMF between them,\nand a solid forms. A more thorough discussion of these and other changes of state, or phase transitions, is\nprovided in a later module of this chapter.\n"]], ["block_6", ["Access this interactive simulation (http://openstax.org/l/16phetvisual) on states of matter, phase transitions,\nand intermolecular forces. This simulation is useful for visualizing concepts introduced throughout this\nchapter.\n"]], ["block_7", ["LINK TO LEARNING\n"]], ["block_8", [{"image_0": "490_0.png", "coords": [130, 57, 481, 203]}]], ["block_9", [{"image_1": "490_1.png", "coords": [247, 320, 364, 564]}]], ["block_10", [" 10.1 \u2022 Intermolecular Forces \n 477 \n"]]], "page_491": [["block_0", [" 478 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [" Forces between Molecules \n"]], ["block_2", ["Under appropriate conditions, the attractions between all gas molecules will cause them to form liquids or\nsolids. This is due to intermolecular forces, not intramolecular forces. Intramolecular forces are those within\nthe molecule that keep the molecule together, for example, the bonds between the atoms. Intermolecular\nforces are the attractions between molecules, which determine many of the physical properties of a substance.\nFigure 10.5 illustrates these different molecular forces. The strengths of these attractive forces vary widely,\nthough usually the IMFs between small molecules are weak compared to the intramolecular forces that bond\natoms together within a molecule. For example, to overcome the IMFs in one mole of liquid HCl and convert it\ninto gaseous HCl requires only about 17 kilojoules. However, to break the covalent bonds between the\nhydrogen and chlorine atoms in one mole of HCl requires about 25 times more energy\u2014430 kilojoules.\n"]], ["block_3", [" FIGURE 10.5 \nIntramolecular forces keep a molecule intact. Intermolecular forces hold multiple molecules\n"]], ["block_4", ["together and determine many of a substance\u2019s properties.\n"]], ["block_5", ["All of the attractive forces between neutral atoms and molecules are known as van der Waals forces , although\nthey are usually referred to more informally as intermolecular attraction. We will consider the various types of\nIMFs in the next three sections of this module.\n"]], ["block_6", [" Dispersion Forces \n"]], ["block_7", ["One of the three van der Waals forces is present in all condensed phases, regardless of the nature of the atoms\nor molecules composing the substance. This attractive force is called the London dispersion force in honor of\nGerman-born American physicist Fritz London who, in 1928, first explained it. This force is often referred to as\nsimply the dispersion force . Because the electrons of an atom or molecule are in constant motion (or,\nalternatively, the electron\u2019s location is subject to quantum-mechanical variability), at any moment in time, an\natom or molecule can develop a temporary, instantaneous dipole if its electrons are distributed\nasymmetrically. The presence of this dipole can, in turn, distort the electrons of a neighboring atom or\nmolecule, producing an induced dipole . These two rapidly fluctuating, temporary dipoles thus result in a\nrelatively weak electrostatic attraction between the species\u2014a so-called dispersion force like that illustrated in\nFigure 10.6.\n"]], ["block_8", [" FIGURE 10.6 \nDispersion forces result from the formation of temporary dipoles, as illustrated here for two nonpolar\n"]], ["block_9", ["diatomic molecules.\n"]], ["block_10", ["Dispersion forces that develop between atoms in different molecules can attract the two molecules to each\nother. The forces are relatively weak, however, and become significant only when the molecules are very close.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", [{"image_0": "491_0.png", "coords": [189, 197, 423, 288]}]], ["block_13", [{"image_1": "491_1.png", "coords": [205, 519, 406, 668]}]]], "page_492": [["block_0", ["Larger and heavier atoms and molecules exhibit stronger dispersion forces than do smaller and lighter atoms\nand molecules. F2 and Cl2 are gases at room temperature (reflecting weaker attractive forces); Br2 is a liquid,\nand I2 is a solid (reflecting stronger attractive forces). Trends in observed melting and boiling points for the\nhalogens clearly demonstrate this effect, as seen in Table 10.1.\n"]], ["block_1", ["The increase in melting and boiling points with increasing atomic/molecular size may be rationalized by\nconsidering how the strength of dispersion forces is affected by the electronic structure of the atoms or\nmolecules in the substance. In a larger atom, the valence electrons are, on average, farther from the nuclei\nthan in a smaller atom. Thus, they are less tightly held and can more easily form the temporary dipoles that\nproduce the attraction. The measure of how easy or difficult it is for another electrostatic charge (for example,\na nearby ion or polar molecule) to distort a molecule\u2019s charge distribution (its electron cloud) is known as\n polarizability . A molecule that has a charge cloud that is easily distorted is said to be very polarizable and will\nhave large dispersion forces; one with a charge cloud that is difficult to distort is not very polarizable and will\nhave small dispersion forces.\n"]], ["block_2", [" London Forces and Their Effects \n"]], ["block_3", ["Order the following compounds of a group 14 element and hydrogen from lowest to highest boiling point: CH4,\nSiH4, GeH4, and SnH4. Explain your reasoning.\n"]], ["block_4", [" Solution \n"]], ["block_5", ["Applying the skills acquired in the chapter on chemical bonding and molecular geometry, all of these\ncompounds are predicted to be nonpolar, so they may experience only dispersion forces: the smaller the\nmolecule, the less polarizable and the weaker the dispersion forces; the larger the molecule, the larger the\ndispersion forces. The molar masses of CH4, SiH4, GeH4, and SnH4 are approximately 16 g/mol, 32 g/mol, 77 g/\nmol, and 123 g/mol, respectively. Therefore, CH4 is expected to have the lowest boiling point and SnH4 the\nhighest boiling point. The ordering from lowest to highest boiling point is expected to be CH4 < SiH4 < GeH4 <\nSnH4.\n"]], ["block_6", ["A graph of the actual boiling points of these compounds versus the period of the group 14 element shows this\nprediction to be correct:\n"]], ["block_7", ["EXAMPLE 10.1\n"]], ["block_8", [" TABLE 10.1 \n"]], ["block_9", ["bromine, Br2\n160 g/mol\n114 pm\n266 K\n332 K\n"]], ["block_10", ["chlorine, Cl2\n71 g/mol\n99 pm\n172 K\n238 K\n"]], ["block_11", ["astatine, At2\n420 g/mol\n150 pm\n575 K\n610 K\n"]], ["block_12", ["fluorine, F2\n38 g/mol\n72 pm\n53 K\n85 K\n"]], ["block_13", ["iodine, I2\n254 g/mol\n133 pm\n387 K\n457 K\n"]], ["block_14", [" Halogen \n Molar Mass \n Atomic Radius \n Melting Point \n Boiling Point \n"]], ["block_15", ["Melting and Boiling Points of the Halogens\n"]], ["block_16", [" 10.1 \u2022 Intermolecular Forces \n 479 \n"]]], "page_493": [["block_0", [" 480 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [{"image_0": "493_0.png", "coords": [72, 57, 432, 290]}]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["Order the following hydrocarbons from lowest to highest boiling point: C2H6, C3H8, and C4H10.\n"]], ["block_4", [" Answer: \nC2H6 < C3H8 < C4H10. All of these compounds are nonpolar and only have London dispersion forces: the larger\nthe molecule, the larger the dispersion forces and the higher the boiling point. The ordering from lowest to\nhighest boiling point is therefore C2H6 < C3H8 < C4H10.\n"]], ["block_5", ["The shapes of molecules also affect the magnitudes of the dispersion forces between them. For example,\nboiling points for the isomers n-pentane, isopentane, and neopentane (shown in Figure 10.7) are 36 \u00b0C, 27 \u00b0C,\nand 9.5 \u00b0C, respectively. Even though these compounds are composed of molecules with the same chemical\nformula, C5H12, the difference in boiling points suggests that dispersion forces in the liquid phase are\ndifferent, being greatest for n-pentane and least for neopentane. The elongated shape of n-pentane provides a\ngreater surface area available for contact between molecules, resulting in correspondingly stronger dispersion\nforces. The more compact shape of isopentane offers a smaller surface area available for intermolecular\ncontact and, therefore, weaker dispersion forces. Neopentane molecules are the most compact of the three,\noffering the least available surface area for intermolecular contact and, hence, the weakest dispersion forces.\nThis behavior is analogous to the connections that may be formed between strips of VELCRO brand fasteners:\nthe greater the area of the strip\u2019s contact, the stronger the connection.\n"]], ["block_6", [" Access for free at openstax.org \n"]]], "page_494": [["block_0", [" FIGURE 10.7 \nThe strength of the dispersion forces increases with the contact area between molecules, as\n"]], ["block_1", ["demonstrated by the boiling points of these pentane isomers.\n"]], ["block_2", ["Chemistry in Everyday Life\n"]], ["block_3", [" Geckos and Intermolecular Forces \nGeckos have an amazing ability to adhere to most surfaces. They can quickly run up smooth walls and\nacross ceilings that have no toe-holds, and they do this without having suction cups or a sticky substance\non their toes. And while a gecko can lift its feet easily as it walks along a surface, if you attempt to pick it up,\nit sticks to the surface. How are geckos (as well as spiders and some other insects) able to do this? Although\nthis phenomenon has been investigated for hundreds of years, scientists only recently uncovered the\ndetails of the process that allows geckos\u2019 feet to behave this way.\n"]], ["block_4", ["Geckos\u2019 toes are covered with hundreds of thousands of tiny hairs known as setae, with each seta, in turn,\nbranching into hundreds of tiny, flat, triangular tips called spatulae. The huge numbers of spatulae on its\nsetae provide a gecko, shown in Figure 10.8, with a large total surface area for sticking to a surface. In 2000,\nKellar Autumn, who leads a multi-institutional gecko research team, found that geckos adhered equally\nwell to both polar silicon dioxide and nonpolar gallium arsenide. This proved that geckos stick to surfaces\nbecause of dispersion forces\u2014weak intermolecular attractions arising from temporary, synchronized\ncharge distributions between adjacent molecules. Although dispersion forces are very weak, the total\nattraction over millions of spatulae is large enough to support many times the gecko\u2019s weight.\n"]], ["block_5", ["In 2014, two scientists developed a model to explain how geckos can rapidly transition from \u201csticky\u201d to\n\u201cnon-sticky.\u201d Alex Greaney and Congcong Hu at Oregon State University described how geckos can achieve\nthis by changing the angle between their spatulae and the surface. Geckos\u2019 feet, which are normally\nnonsticky, become sticky when a small shear force is applied. By curling and uncurling their toes, geckos\ncan alternate between sticking and unsticking from a surface, and thus easily move across it. Later\nresearch led by Alyssa Stark at University of Akron showed that geckos can maintain their hold on\nhydrophobic surfaces (similar to the leaves in their habitats) equally well whether the surfaces were wet or\ndry. Stark's experiment used a ribbon to gently pull the geckos until they slipped, so that the researchers\ncould determine the geckos' ability to hold various surfaces under wet and dry conditions. Further\ninvestigations may eventually lead to the development of better adhesives and other applications.\n"]], ["block_6", [{"image_0": "494_0.png", "coords": [128, 57, 483, 303]}]], ["block_7", [" 10.1 \u2022 Intermolecular Forces \n 481 \n"]]], "page_495": [["block_0", [" 482 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", ["Watch this video (http://openstax.org/l/16kellaraut) to learn more about Kellar Autumn\u2019s research that\ndetermined that van der Waals forces are responsible for a gecko\u2019s ability to cling and climb.\n"]], ["block_2", [" Dipole-Dipole Attractions \n"]], ["block_3", ["Recall from the chapter on chemical bonding and molecular geometry that polar molecules have a partial\npositive charge on one side and a partial negative charge on the other side of the molecule\u2014a separation of\ncharge called a dipole. Consider a polar molecule such as hydrogen chloride, HCl. In the HCl molecule, the\nmore electronegative Cl atom bears the partial negative charge, whereas the less electronegative H atom bears\nthe partial positive charge. An attractive force between HCl molecules results from the attraction between the\npositive end of one HCl molecule and the negative end of another. This attractive force is called a dipole-dipole \n attraction \u2014the electrostatic force between the partially positive end of one polar molecule and the partially\nnegative end of another, as illustrated in Figure 10.9.\n"]], ["block_4", [" FIGURE 10.9 \nThis image shows two arrangements of polar molecules, such as HCl, that allow an attraction\n"]], ["block_5", ["between the partial negative end of one molecule and the partial positive end of another.\n"]], ["block_6", ["The effect of a dipole-dipole attraction is apparent when we compare the properties of HCl molecules to\nnonpolar F2 molecules. Both HCl and F2 consist of the same number of atoms and have approximately the\nsame molecular mass. At a temperature of 150 K, molecules of both substances would have the same average\nKE. However, the dipole-dipole attractions between HCl molecules are sufficient to cause them to \u201cstick\ntogether\u201d to form a liquid, whereas the relatively weaker dispersion forces between nonpolar F2 molecules are\nnot, and so this substance is gaseous at this temperature. The higher normal boiling point of HCl (188 K)\ncompared to F2 (85 K) is a reflection of the greater strength of dipole-dipole attractions between HCl\nmolecules, compared to the attractions between nonpolar F2 molecules. We will often use values such as\nboiling or freezing points, or enthalpies of vaporization or fusion, as indicators of the relative strengths of IMFs\nof attraction present within different substances.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [" FIGURE 10.8 \nGeckos\u2019 toes contain large numbers of tiny hairs (setae), which branch into many triangular tips\n"]], ["block_9", ["(spatulae). Geckos adhere to surfaces because of van der Waals attractions between the surface and a gecko\u2019s\nmillions of spatulae. By changing how the spatulae contact the surface, geckos can turn their stickiness \u201con\u201d and\n\u201coff.\u201d (credit photo: modification of work by \u201cJC*+A!\u201d/Flickr)\n"]], ["block_10", ["LINK TO LEARNING\n"]], ["block_11", [{"image_0": "495_0.png", "coords": [100, 57, 511, 200]}]], ["block_12", [{"image_1": "495_1.png", "coords": [130, 473, 481, 557]}]]], "page_496": [["block_0", [" Dipole-Dipole Forces and Their Effects \n"]], ["block_1", ["Predict which will have the higher boiling point: N2 or CO. Explain your reasoning.\n"]], ["block_2", [" Solution \n"]], ["block_3", ["CO and N2 are both diatomic molecules with masses of about 28 amu, so they experience similar London\ndispersion forces. Because CO is a polar molecule, it experiences dipole-dipole attractions. Because N2 is\nnonpolar, its molecules cannot exhibit dipole-dipole attractions. The dipole-dipole attractions between CO\nmolecules are comparably stronger than the dispersion forces between nonpolar N2 molecules, so CO is\nexpected to have the higher boiling point.\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["Predict which will have the higher boiling point: ICl or Br2. Explain your reasoning.\n"]], ["block_6", [" Answer: \nICl. ICl and Br2 have similar masses (~160 amu) and therefore experience similar London dispersion forces. ICl\nis polar and thus also exhibits dipole-dipole attractions; Br2 is nonpolar and does not. The relatively stronger\ndipole-dipole attractions require more energy to overcome, so ICl will have the higher boiling point.\n"]], ["block_7", [" Hydrogen Bonding \n"]], ["block_8", ["Nitrosyl fluoride (ONF, molecular mass 49 amu) is a gas at room temperature. Water (H2O, molecular mass 18\namu) is a liquid, even though it has a lower molecular mass. We clearly cannot attribute this difference\nbetween the two compounds to dispersion forces. Both molecules have about the same shape and ONF is the\nheavier and larger molecule. It is, therefore, expected to experience more significant dispersion forces.\nAdditionally, we cannot attribute this difference in boiling points to differences in the dipole moments of the\nmolecules. Both molecules are polar and exhibit comparable dipole moments. The large difference between\nthe boiling points is due to a particularly strong dipole-dipole attraction that may occur when a molecule\ncontains a hydrogen atom bonded to a fluorine, oxygen, or nitrogen atom (the three most electronegative\nelements). The very large difference in electronegativity between the H atom (2.1) and the atom to which it is\nbonded (4.0 for an F atom, 3.5 for an O atom, or 3.0 for a N atom), combined with the very small size of a H\natom and the relatively small sizes of F, O, or N atoms, leads to highly concentrated partial charges with these\natoms. Molecules with F-H, O-H, or N-H moieties are very strongly attracted to similar moieties in nearby\nmolecules, a particularly strong type of dipole-dipole attraction called hydrogen bonding . Examples of\nhydrogen bonds include HF\u22efHF, H2O\u22efHOH, and H3N\u22efHNH2, in which the hydrogen bonds are denoted by\ndots. Figure 10.10 illustrates hydrogen bonding between water molecules.\n"]], ["block_9", [" FIGURE 10.10 \nWater molecules participate in multiple hydrogen-bonding interactions with nearby water\n"]], ["block_10", ["molecules.\n"]], ["block_11", ["EXAMPLE 10.2\n"]], ["block_12", [{"image_0": "496_0.png", "coords": [136, 532, 475, 699]}]], ["block_13", [" 10.1 \u2022 Intermolecular Forces \n 483 \n"]]], "page_497": [["block_0", [" 484 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", ["Despite use of the word \u201cbond,\u201d keep in mind that hydrogen bonds are intermolecular attractive forces, not\nintramolecular attractive forces (covalent bonds). Hydrogen bonds are much weaker than covalent bonds, only\nabout 5 to 10% as strong, but are generally much stronger than other dipole-dipole attractions and dispersion\nforces.\n"]], ["block_2", ["Hydrogen bonds have a pronounced effect on the properties of condensed phases (liquids and solids). For\nexample, consider the trends in boiling points for the binary hydrides of group 15 (NH3, PH3, AsH3, and SbH3),\ngroup 16 hydrides (H2O, H2S, H2Se, and H2Te), and group 17 hydrides (HF, HCl, HBr, and HI). The boiling\npoints of the heaviest three hydrides for each group are plotted in Figure 10.11. As we progress down any of\nthese groups, the polarities of the molecules decrease slightly, whereas the sizes of the molecules increase\nsubstantially. The effect of increasingly stronger dispersion forces dominates that of increasingly weaker\ndipole-dipole attractions, and the boiling points are observed to increase steadily.\n"]], ["block_3", [" FIGURE 10.11 \nFor the group 15, 16, and 17 hydrides, the boiling points for each class of compounds increase with\n"]], ["block_4", ["increasing molecular mass for elements in periods 3, 4, and 5.\n"]], ["block_5", ["If we use this trend to predict the boiling points for the lightest hydride for each group, we would expect NH3 to\nboil at about \u2212120 \u00b0C, H2O to boil at about \u221280 \u00b0C, and HF to boil at about \u2212110 \u00b0C. However, when we measure\nthe boiling points for these compounds, we find that they are dramatically higher than the trends would\npredict, as shown in Figure 10.12. The stark contrast between our na\u00efve predictions and reality provides\ncompelling evidence for the strength of hydrogen bonding.\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [{"image_0": "497_0.png", "coords": [130, 208, 481, 510]}]]], "page_498": [["block_0", [" FIGURE 10.12 \nIn comparison to periods 3\u22125, the binary hydrides of period 2 elements in groups 17, 16 and 15 (F,\n"]], ["block_1", ["O and N, respectively) exhibit anomalously high boiling points due to hydrogen bonding.\n"]], ["block_2", [" Effect of Hydrogen Bonding on Boiling Points \n"]], ["block_3", ["Consider the compounds dimethylether (CH3OCH3), ethanol (CH3CH2OH), and propane (CH3CH2CH3). Their\nboiling points, not necessarily in order, are \u221242.1 \u00b0C, \u221224.8 \u00b0C, and 78.4 \u00b0C. Match each compound with its\nboiling point. Explain your reasoning.\n"]], ["block_4", [" Solution \n"]], ["block_5", ["The VSEPR-predicted shapes of CH3OCH3, CH3CH2OH, and CH3CH2CH3 are similar, as are their molar masses\n(46 g/mol, 46 g/mol, and 44 g/mol, respectively), so they will exhibit similar dispersion forces. Since\nCH3CH2CH3 is nonpolar, it may exhibit only dispersion forces. Because CH3OCH3 is polar, it will also\nexperience dipole-dipole attractions. Finally, CH3CH2OH has an \u2212OH group, and so it will experience the\nuniquely strong dipole-dipole attraction known as hydrogen bonding. So the ordering in terms of strength of\nIMFs, and thus boiling points, is CH3CH2CH3 < CH3OCH3 < CH3CH2OH. The boiling point of propane is \u221242.1\n\u00b0C, the boiling point of dimethylether is \u221224.8 \u00b0C, and the boiling point of ethanol is 78.5 \u00b0C.\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["Ethane (CH3CH3) has a melting point of \u2212183 \u00b0C and a boiling point of \u221289 \u00b0C. Predict the melting and boiling\npoints for methylamine (CH3NH2). Explain your reasoning.\n"]], ["block_8", [" Answer: \nThe melting point and boiling point for methylamine are predicted to be significantly greater than those of\nethane. CH3CH3 and CH3NH2 are similar in size and mass, but methylamine possesses an \u2212NH group and\ntherefore may exhibit hydrogen bonding. This greatly increases its IMFs, and therefore its melting and boiling\npoints. It is difficult to predict values, but the known values are a melting point of \u221293 \u00b0C and a boiling point of\n\u22126 \u00b0C.\n"]], ["block_9", ["EXAMPLE 10.3\n"]], ["block_10", [{"image_0": "498_0.png", "coords": [130, 57, 481, 357]}]], ["block_11", [" 10.1 \u2022 Intermolecular Forces \n 485 \n"]]], "page_499": [["block_0", [" 486 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [" Hydrogen Bonding and DNA \nDeoxyribonucleic acid (DNA) is found in every living organism and contains the genetic information that\ndetermines the organism\u2019s characteristics, provides the blueprint for making the proteins necessary for life,\nand serves as a template to pass this information on to the organism\u2019s offspring. A DNA molecule consists of\ntwo (anti-)parallel chains of repeating nucleotides, which form its well-known double helical structure, as\nshown in Figure 10.13.\n"]], ["block_2", [" FIGURE 10.13 \nTwo separate DNA molecules form a double-stranded helix in which the molecules are held\n"]], ["block_3", ["together via hydrogen bonding. (credit: modification of work by Jerome Walker, Dennis Myts)\n"]], ["block_4", ["Each nucleotide contains a (deoxyribose) sugar bound to a phosphate group on one side, and one of four\nnitrogenous bases on the other. Two of the bases, cytosine (C) and thymine (T), are single-ringed structures\nknown as pyrimidines. The other two, adenine (A) and guanine (G), are double-ringed structures called\npurines. These bases form complementary base pairs consisting of one purine and one pyrimidine, with\nadenine pairing with thymine, and cytosine with guanine. Each base pair is held together by hydrogen\nbonding. A and T share two hydrogen bonds, C and G share three, and both pairings have a similar shape and\nstructure Figure 10.14.\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", ["HOW SCIENCES INTERCONNECT\n"]], ["block_7", [{"image_0": "499_0.png", "coords": [247, 173, 364, 354]}]]], "page_500": [["block_0", [" FIGURE 10.14 \nThe geometries of the base molecules result in maximum hydrogen bonding between adenine and\n"]], ["block_1", ["thymine (AT) and between guanine and cytosine (GC), so-called \u201ccomplementary base pairs.\u201d\n"]], ["block_2", ["The cumulative effect of millions of hydrogen bonds effectively holds the two strands of DNA together.\nImportantly, the two strands of DNA can relatively easily \u201cunzip\u201d down the middle since hydrogen bonds are\nrelatively weak compared to the covalent bonds that hold the atoms of the individual DNA molecules together.\nThis allows both strands to function as a template for replication.\n"]], ["block_3", [" 10.2 Properties of Liquids \n"]], ["block_4", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_5", ["When you pour a glass of water, or fill a car with gasoline, you observe that water and gasoline flow freely. But\nwhen you pour syrup on pancakes or add oil to a car engine, you note that syrup and motor oil do not flow as\nreadily. The viscosity of a liquid is a measure of its resistance to flow. Water, gasoline, and other liquids that\nflow freely have a low viscosity. Honey, syrup, motor oil, and other liquids that do not flow freely, like those\nshown in Figure 10.15, have higher viscosities. We can measure viscosity by measuring the rate at which a\nmetal ball falls through a liquid (the ball falls more slowly through a more viscous liquid) or by measuring the\nrate at which a liquid flows through a narrow tube (more viscous liquids flow more slowly).\n"]], ["block_6", ["\u2022\nDistinguish between adhesive and cohesive forces\n"]], ["block_7", ["\u2022\nDefine viscosity, surface tension, and capillary rise\n"]], ["block_8", ["\u2022\nDescribe the roles of intermolecular attractive forces in each of these properties/phenomena\n"]], ["block_9", [{"image_0": "500_0.png", "coords": [130, 57, 481, 296]}]], ["block_10", [" 10.2 \u2022 Properties of Liquids \n 487 \n"]]], "page_501": [["block_0", [" 488 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [" FIGURE 10.15 \n(a) Honey and (b) motor oil are examples of liquids with high viscosities; they flow slowly. (credit a:\n"]], ["block_2", ["modification of work by Scott Bauer; credit b: modification of work by David Nagy)\n"]], ["block_3", ["The IMFs between the molecules of a liquid, the size and shape of the molecules, and the temperature\ndetermine how easily a liquid flows. As Table 10.2 shows, the more structurally complex are the molecules in a\nliquid and the stronger the IMFs between them, the more difficult it is for them to move past each other and the\ngreater is the viscosity of the liquid. As the temperature increases, the molecules move more rapidly and their\nkinetic energies are better able to overcome the forces that hold them together; thus, the viscosity of the liquid\ndecreases.\n"]], ["block_4", ["The various IMFs between identical molecules of a substance are examples of cohesive forces . The molecules\nwithin a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive\nforces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half\nas many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids\ncontract to form a shape that minimizes the number of molecules on the surface\u2014that is, the shape with the\nminimum surface area. A small drop of liquid tends to assume a spherical shape, as shown in Figure 10.16,\nbecause in a sphere, the ratio of surface area to volume is at a minimum. Larger drops are more greatly\naffected by gravity, air resistance, surface interactions, and so on, and as a result, are less spherical.\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", [{"image_0": "501_0.png", "coords": [130, 57, 481, 237]}]], ["block_7", [" TABLE 10.2 \n"]], ["block_8", ["ethylene glycol\nCH2(OH)CH2(OH)\n16.1\n"]], ["block_9", [" Substance \n Formula \n Viscosity (mPa\u00b7s) \n"]], ["block_10", ["motor oil\nvariable\n~50\u2013500\n"]], ["block_11", ["mercury\nHg\n1.526\n"]], ["block_12", ["ethanol\nC2H5OH\n1.074\n"]], ["block_13", ["octane\nC8H18\n0.508\n"]], ["block_14", ["honey\nvariable\n~2,000\u201310,000\n"]], ["block_15", ["water\nH2O\n0.890\n"]], ["block_16", ["Viscosities of Common Substances at 25 \u00b0C\n"]]], "page_502": [["block_0", [" FIGURE 10.16 \nAttractive forces result in a spherical water drop that minimizes surface area; cohesive forces hold\n"]], ["block_1", ["the sphere together; adhesive forces keep the drop attached to the web. (credit photo: modification of work by\n\u201cOliBac\u201d/Flickr)\n"]], ["block_2", [" Surface tension is defined as the energy required to increase the surface area of a liquid, or the force required\nto increase the length of a liquid surface by a given amount. This property results from the cohesive forces\nbetween molecules at the surface of a liquid, and it causes the surface of a liquid to behave like a stretched\nrubber membrane. Surface tensions of several liquids are presented in Table 10.3. Among common liquids,\nwater exhibits a distinctly high surface tension due to strong hydrogen bonding between its molecules. As a\nresult of this high surface tension, the surface of water represents a relatively \u201ctough skin\u201d that can withstand\nconsiderable force without breaking. A steel needle carefully placed on water will float. Some insects, like the\none shown in Figure 10.17, even though they are denser than water, move on its surface because they are\nsupported by the surface tension.\n"]], ["block_3", ["Surface tension is affected by a variety of variables, including the introduction of additional substances on the\nsurface. In the late 1800s, Agnes Pockels, who was initially blocked from pursuing a scientific career but\n"]], ["block_4", [" FIGURE 10.17 \nSurface tension (right) prevents this insect, a \u201cwater strider,\u201d from sinking into the water.\n"]], ["block_5", [{"image_0": "502_0.png", "coords": [130, 57, 481, 221]}]], ["block_6", [{"image_1": "502_1.png", "coords": [130, 600, 481, 684]}]], ["block_7", [" TABLE 10.3 \n"]], ["block_8", ["ethylene glycol\nCH2(OH)CH2(OH)\n47.99\n"]], ["block_9", [" Substance \n Formula \n Surface Tension (mN/m) \n"]], ["block_10", ["mercury\nHg\n458.48\n"]], ["block_11", ["ethanol\nC2H5OH\n21.97\n"]], ["block_12", ["octane\nC8H18\n21.14\n"]], ["block_13", ["water\nH2O\n71.99\n"]], ["block_14", ["Surface Tensions of Common Substances at 25 \u00b0C\n"]], ["block_15", [" 10.2 \u2022 Properties of Liquids \n 489 \n"]]], "page_503": [["block_0", [" 490 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", ["studied on her own, began investigating the impact and characteristics of soapy and greasy films in water.\nUsing homemade materials, she developed an instrument known as a trough for measuring surface\ncontaminants and their effects. With the support of renowned scientist Lord Rayleigh, her 1891 paper showed\nthat surface contamination significantly reduces surface tension, and also that changing the characteristics of\nthe surface (compressing or expanding it) also affects surface tension. Decades later, Irving Langmuir and\nKatharine Blodgett built on Pockels' work in their own trough and important advances in surface chemistry.\nLangmuir pioneered methods for producing single-molecule layers of film; Blodgett applied these to the\ndevelopment of non-reflective glass (critical for film-making and other applications), and also studied methods\nrelated to cleaning surfaces, which are important in semiconductor fabrication.\n"]], ["block_2", ["The IMFs of attraction between two different molecules are called adhesive forces . Consider what happens\nwhen water comes into contact with some surface. If the adhesive forces between water molecules and the\nmolecules of the surface are weak compared to the cohesive forces between the water molecules, the water\ndoes not \u201cwet\u201d the surface. For example, water does not wet waxed surfaces or many plastics such as\npolyethylene. Water forms drops on these surfaces because the cohesive forces within the drops are greater\nthan the adhesive forces between the water and the plastic. Water spreads out on glass because the adhesive\nforce between water and glass is greater than the cohesive forces within the water. When water is confined in a\nglass tube, its meniscus (surface) has a concave shape because the water wets the glass and creeps up the side\nof the tube. On the other hand, the cohesive forces between mercury atoms are much greater than the adhesive\nforces between mercury and glass. Mercury therefore does not wet glass, and it forms a convex meniscus when\nconfined in a tube because the cohesive forces within the mercury tend to draw it into a drop (Figure 10.18).\n"]], ["block_3", [" FIGURE 10.18 \nDifferences in the relative strengths of cohesive and adhesive forces result in different meniscus\n"]], ["block_4", ["shapes for mercury (left) and water (right) in glass tubes. (credit: Mark Ott)\n"]], ["block_5", ["If you place one end of a paper towel in spilled wine, as shown in Figure 10.19, the liquid wicks up the paper\ntowel. A similar process occurs in a cloth towel when you use it to dry off after a shower. These are examples of\n capillary action \u2014when a liquid flows within a porous material due to the attraction of the liquid molecules to\nthe surface of the material and to other liquid molecules. The adhesive forces between the liquid and the\nporous material, combined with the cohesive forces within the liquid, may be strong enough to move the liquid\nupward against gravity.\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [{"image_0": "503_0.png", "coords": [189, 322, 423, 478]}]]], "page_504": [["block_0", [" FIGURE 10.19 \nWine wicks up a paper towel (left) because of the strong attractions of water (and ethanol)\n"]], ["block_1", ["molecules to the \u2212OH groups on the towel\u2019s cellulose fibers and the strong attractions of water molecules to other\nwater (and ethanol) molecules (right). (credit photo: modification of work by Mark Blaser)\n"]], ["block_2", ["Towels soak up liquids like water because the fibers of a towel are made of molecules that are attracted to\nwater molecules. Most cloth towels are made of cotton, and paper towels are generally made from paper pulp.\nBoth consist of long molecules of cellulose that contain many \u2212OH groups. Water molecules are attracted to\nthese \u2212OH groups and form hydrogen bonds with them, which draws the H2O molecules up the cellulose\nmolecules. The water molecules are also attracted to each other, so large amounts of water are drawn up the\ncellulose fibers.\n"]], ["block_3", ["Capillary action can also occur when one end of a small diameter tube is immersed in a liquid, as illustrated in\nFigure 10.20. If the liquid molecules are strongly attracted to the tube molecules, the liquid creeps up the\ninside of the tube until the weight of the liquid and the adhesive forces are in balance. The smaller the\ndiameter of the tube is, the higher the liquid climbs. It is partly by capillary action occurring in plant cells\ncalled xylem that water and dissolved nutrients are brought from the soil up through the roots and into a plant.\nCapillary action is the basis for thin layer chromatography, a laboratory technique commonly used to separate\nsmall quantities of mixtures. You depend on a constant supply of tears to keep your eyes lubricated and on\ncapillary action to pump tear fluid away.\n"]], ["block_4", [" FIGURE 10.20 \nDepending upon the relative strengths of adhesive and cohesive forces, a liquid may rise (such as\n"]], ["block_5", ["water) or fall (such as mercury) in a glass capillary tube. The extent of the rise (or fall) is directly proportional to the\nsurface tension of the liquid and inversely proportional to the density of the liquid and the radius of the tube.\n"]], ["block_6", ["The height to which a liquid will rise in a capillary tube is determined by several factors as shown in the\n"]], ["block_7", [{"image_0": "504_0.png", "coords": [93, 57, 518, 271]}]], ["block_8", [{"image_1": "504_1.png", "coords": [130, 507, 481, 670]}]], ["block_9", [" 10.2 \u2022 Properties of Liquids \n 491 \n"]]], "page_505": [["block_0", [" 492 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", ["following equation:\n"]], ["block_2", ["In this equation, h is the height of the liquid inside the capillary tube relative to the surface of the liquid outside\nthe tube, T is the surface tension of the liquid, \u03b8 is the contact angle between the liquid and the tube, r is the\nradius of the tube, \u03c1 is the density of the liquid, and g is the acceleration due to gravity, 9.8 m/s. When the tube\nis made of a material to which the liquid molecules are strongly attracted, they will spread out completely on\nthe surface, which corresponds to a contact angle of 0\u00b0. This is the situation for water rising in a glass tube.\n"]], ["block_3", [" Capillary Rise \n"]], ["block_4", ["At 25 \u00b0C, how high will water rise in a glass capillary tube with an inner diameter of 0.25 mm?\n"]], ["block_5", ["For water, T = 71.99 mN/m and \u03c1 = 1.0 g/cm.\n"]], ["block_6", [" Solution \n"]], ["block_7", ["The liquid will rise to a height h given by:\n"]], ["block_8", ["The Newton is defined as a kg m/s, and so the provided surface tension is equivalent to 0.07199 kg/s. The\nprovided density must be converted into units that will cancel appropriately: \u03c1 = 1000 kg/m. The diameter of\nthe tube in meters is 0.00025 m, so the radius is 0.000125 m. For a glass tube immersed in water, the contact\nangle is \u03b8 = 0\u00b0, so cos \u03b8 = 1. Finally, acceleration due to gravity on the earth is g = 9.8 m/s. Substituting these\nvalues into the equation, and cancelling units, we have:\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["Water rises in a glass capillary tube to a height of 8.4 cm. What is the diameter of the capillary tube?\n"]], ["block_11", [" Answer: \ndiameter = 0.36 mm\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["Chemistry in Everyday Life\n"]], ["block_14", [" Biomedical Applications of Capillary Action \nMany medical tests require drawing a small amount of blood, for example to determine the amount of\nglucose in someone with diabetes or the hematocrit level in an athlete. This procedure can be easily done\nbecause of capillary action, the ability of a liquid to flow up a small tube against gravity, as shown in Figure\n10.21. When your finger is pricked, a drop of blood forms and holds together due to surface tension\u2014the\nunbalanced intermolecular attractions at the surface of the drop. Then, when the open end of a narrow-\ndiameter glass tube touches the drop of blood, the adhesive forces between the molecules in the blood and\nthose at the glass surface draw the blood up the tube. How far the blood goes up the tube depends on the\ndiameter of the tube (and the type of fluid). A small tube has a relatively large surface area for a given\nvolume of blood, which results in larger (relative) attractive forces, allowing the blood to be drawn farther\nup the tube. The liquid itself is held together by its own cohesive forces. When the weight of the liquid in the\ntube generates a downward force equal to the upward force associated with capillary action, the liquid\nstops rising.\n"]], ["block_15", ["EXAMPLE 10.4\n"]]], "page_506": [["block_0", [" 10.3 Phase Transitions \n"]], ["block_1", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_2", ["We witness and utilize changes of physical state, or phase transitions, in a great number of ways. As one\nexample of global significance, consider the evaporation, condensation, freezing, and melting of water. These\nchanges of state are essential aspects of our earth\u2019s water cycle as well as many other natural phenomena and\ntechnological processes of central importance to our lives. In this module, the essential aspects of phase\ntransitions are explored.\n"]], ["block_3", [" Vaporization and Condensation \n"]], ["block_4", ["When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase molecules\nmove randomly about, they will occasionally collide with the surface of the condensed phase, and in some\ncases, these collisions will result in the molecules re-entering the condensed phase. The change from the gas\nphase to the liquid is called condensation . When the rate of condensation becomes equal to the rate of\n vaporization , neither the amount of the liquid nor the amount of the vapor in the container changes. The\nvapor in the container is then said to be in equilibrium with the liquid. Keep in mind that this is not a static\nsituation, as molecules are continually exchanged between the condensed and gaseous phases. Such is an\nexample of a dynamic equilibrium , the status of a system in which reciprocal processes (for example,\nvaporization and condensation) occur at equal rates. The pressure exerted by the vapor in equilibrium with a\nliquid in a closed container at a given temperature is called the liquid\u2019s vapor pressure (or equilibrium vapor\npressure). The area of the surface of the liquid in contact with a vapor and the size of the vessel have no effect\non the vapor pressure, although they do affect the time required for the equilibrium to be reached. We can\nmeasure the vapor pressure of a liquid by placing a sample in a closed container, like that illustrated in Figure\n10.22, and using a manometer to measure the increase in pressure that is due to the vapor in equilibrium with\nthe condensed phase.\n"]], ["block_5", [" FIGURE 10.22 \nIn a closed container, dynamic equilibrium is reached when (a) the rate of molecules escaping from\n"]], ["block_6", ["\u2022\nDefine phase transitions and phase transition temperatures\n"]], ["block_7", ["\u2022\nExplain the relation between phase transition temperatures and intermolecular attractive forces\n"]], ["block_8", ["\u2022\nDescribe the processes represented by typical heating and cooling curves, and compute heat flows and\nenthalpy changes accompanying these processes\n"]], ["block_9", [" FIGURE 10.21 \nBlood is collected for medical analysis by capillary action, which draws blood into a small\n"]], ["block_10", ["diameter glass tube. (credit: modification of work by Centers for Disease Control and Prevention)\n"]], ["block_11", [{"image_0": "506_0.png", "coords": [110, 592, 501, 717]}]], ["block_12", [{"image_1": "506_1.png", "coords": [247, 57, 364, 145]}]], ["block_13", [" 10.3 \u2022 Phase Transitions \n 493 \n"]]], "page_507": [["block_0", [" 494 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", ["the liquid to become the gas (b) increases and eventually (c) equals the rate of gas molecules entering the liquid.\nWhen this equilibrium is reached, the vapor pressure of the gas is constant, although the vaporization and\ncondensation processes continue.\n"]], ["block_2", ["The chemical identities of the molecules in a liquid determine the types (and strengths) of intermolecular\nattractions possible; consequently, different substances will exhibit different equilibrium vapor pressures.\nRelatively strong intermolecular attractive forces will serve to impede vaporization as well as favoring\n\u201crecapture\u201d of gas-phase molecules when they collide with the liquid surface, resulting in a relatively low vapor\npressure. Weak intermolecular attractions present less of a barrier to vaporization, and a reduced likelihood of\ngas recapture, yielding relatively high vapor pressures. The following example illustrates this dependence of\nvapor pressure on intermolecular attractive forces.\n"]], ["block_3", [" Explaining Vapor Pressure in Terms of IMFs \n"]], ["block_4", ["Given the shown structural formulas for these four compounds, explain their relative vapor pressures in terms\nof types and extents of IMFs:\n"]], ["block_5", [{"image_0": "507_0.png", "coords": [72, 276, 432, 328]}]], ["block_6", [" Solution \n"]], ["block_7", ["Diethyl ether has a very small dipole and most of its intermolecular attractions are London forces. Although\nthis molecule is the largest of the four under consideration, its IMFs are the weakest and, as a result, its\nmolecules most readily escape from the liquid. It also has the highest vapor pressure. Due to its smaller size,\nethanol exhibits weaker dispersion forces than diethyl ether. However, ethanol is capable of hydrogen bonding\nand, therefore, exhibits stronger overall IMFs, which means that fewer molecules escape from the liquid at any\ngiven temperature, and so ethanol has a lower vapor pressure than diethyl ether. Water is much smaller than\neither of the previous substances and exhibits weaker dispersion forces, but its extensive hydrogen bonding\nprovides stronger intermolecular attractions, fewer molecules escaping the liquid, and a lower vapor pressure\nthan for either diethyl ether or ethanol. Ethylene glycol has two \u2212OH groups, so, like water, it exhibits extensive\nhydrogen bonding. It is much larger than water and thus experiences larger London forces. Its overall IMFs are\nthe largest of these four substances, which means its vaporization rate will be the slowest and, consequently,\nits vapor pressure the lowest.\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["At 20 \u00b0C, the vapor pressures of several alcohols are given in this table. Explain these vapor pressures in terms\nof types and extents of IMFs for these alcohols:\n"]], ["block_10", [" Answer: \nAll these compounds exhibit hydrogen bonding; these strong IMFs are difficult for the molecules to overcome,\nso the vapor pressures are relatively low. As the size of molecule increases from methanol to butanol,\ndispersion forces increase, which means that the vapor pressures decrease as observed:\nPmethanol > Pethanol > Ppropanol > Pbutanol.\n"]], ["block_11", ["As temperature increases, the vapor pressure of a liquid also increases due to the increased average KE of its\nmolecules. Recall that at any given temperature, the molecules of a substance experience a range of kinetic\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["Compound\nmethanol CH3OH\nethanol C2H5OH\npropanol C3H7OH\nbutanol C4H9OH\n"]], ["block_14", ["Vapor Pressure at 20 \u00b0C\n11.9 kPa\n5.95 kPa\n2.67 kPa\n0.56 kPa\n"]], ["block_15", ["EXAMPLE 10.5\n"]]], "page_508": [["block_0", ["energies, with a certain fraction of molecules having a sufficient energy to overcome IMF and escape the liquid\n(vaporize). At a higher temperature, a greater fraction of molecules have enough energy to escape from the\nliquid, as shown in Figure 10.23. The escape of more molecules per unit of time and the greater average speed\nof the molecules that escape both contribute to the higher vapor pressure.\n"]], ["block_1", [" FIGURE 10.23 \nTemperature affects the distribution of kinetic energies for the molecules in a liquid. At the higher\n"]], ["block_2", ["temperature, more molecules have the necessary kinetic energy, KE, to escape from the liquid into the gas phase.\n"]], ["block_3", [" Boiling Points \n"]], ["block_4", ["When the vapor pressure increases enough to equal the external atmospheric pressure, the liquid reaches its\nboiling point. The boiling point of a liquid is the temperature at which its equilibrium vapor pressure is equal\nto the pressure exerted on the liquid by its gaseous surroundings. For liquids in open containers, this pressure\nis that due to the earth\u2019s atmosphere. The normal boiling point of a liquid is defined as its boiling point when\nsurrounding pressure is equal to 1 atm (101.3 kPa). Figure 10.24 shows the variation in vapor pressure with\ntemperature for several different substances. Considering the definition of boiling point, these curves may be\nseen as depicting the dependence of a liquid\u2019s boiling point on surrounding pressure.\n"]], ["block_5", [" FIGURE 10.24 \nThe boiling points of liquids are the temperatures at which their equilibrium vapor pressures equal\n"]], ["block_6", ["the pressure of the surrounding atmosphere. Normal boiling points are those corresponding to a pressure of 1 atm\n(101.3 kPa.)\n"]], ["block_7", [{"image_0": "508_0.png", "coords": [130, 403, 481, 648]}]], ["block_8", [{"image_1": "508_1.png", "coords": [189, 114, 423, 254]}]], ["block_9", [" 10.3 \u2022 Phase Transitions \n 495 \n"]]], "page_509": [["block_0", [" 496 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [" A Boiling Point at Reduced Pressure \n"]], ["block_2", ["A typical atmospheric pressure in Leadville, Colorado (elevation 10,200 feet) is 68 kPa. Use the graph in Figure\n10.24 to determine the boiling point of water at this elevation.\n"]], ["block_3", [" Solution \n"]], ["block_4", ["The graph of the vapor pressure of water versus temperature in Figure 10.24 indicates that the vapor pressure\nof water is 68 kPa at about 90 \u00b0C. Thus, at about 90 \u00b0C, the vapor pressure of water will equal the atmospheric\npressure in Leadville, and water will boil.\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["The boiling point of ethyl ether was measured to be 10 \u00b0C at a base camp on the slopes of Mount Everest. Use\nFigure 10.24 to determine the approximate atmospheric pressure at the camp.\n"]], ["block_7", [" Answer: \nApproximately 40 kPa (0.4 atm)\n"]], ["block_8", ["The quantitative relation between a substance\u2019s vapor pressure and its temperature is described by the\n Clausius-Clapeyron equation :\n"]], ["block_9", ["where \u0394Hvap is the enthalpy of vaporization for the liquid, R is the gas constant, and A is a constant whose\nvalue depends on the chemical identity of the substance. Temperature T must be in Kelvin in this equation.\nThis equation is often rearranged into logarithmic form to yield the linear equation:\n"]], ["block_10", ["This linear equation may be expressed in a two-point format that is convenient for use in various\ncomputations, as demonstrated in the example exercises that follow. If at temperature T1, the vapor pressure is\nP1, and at temperature T2, the vapor pressure is P2, the corresponding linear equations are:\n"]], ["block_11", ["Since the constant, A, is the same, these two equations may be rearranged to isolate ln A and then set them\nequal to one another:\n"]], ["block_12", ["which can be combined into:\n"]], ["block_13", [" Estimating Enthalpy of Vaporization \n"]], ["block_14", ["Isooctane (2,2,4-trimethylpentane) has an octane rating of 100. It is used as one of the standards for the\noctane-rating system for gasoline. At 34.0 \u00b0C, the vapor pressure of isooctane is 10.0 kPa, and at 98.8 \u00b0C, its\nvapor pressure is 100.0 kPa. Use this information to estimate the enthalpy of vaporization for isooctane.\n"]], ["block_15", [" Solution \n"]], ["block_16", ["The enthalpy of vaporization, \u0394Hvap, can be determined by using the Clausius-Clapeyron equation:\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["EXAMPLE 10.6\n"]], ["block_19", ["EXAMPLE 10.7\n"]]], "page_510": [["block_0", ["Since we have two vapor pressure-temperature values (T1 = 34.0 \u00b0C = 307.2 K, P1 = 10.0 kPa and T2 = 98.8 \u00b0C =\n372.0 K, P2 = 100 kPa), we can substitute them into this equation and solve for \u0394Hvap. Rearranging the\nClausius-Clapeyron equation and solving for \u0394Hvap yields:\n"]], ["block_1", ["Note that the pressure can be in any units, so long as they agree for both P values, but the temperature must be\nin kelvin for the Clausius-Clapeyron equation to be valid.\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["At 20.0 \u00b0C, the vapor pressure of ethanol is 5.95 kPa, and at 63.5 \u00b0C, its vapor pressure is 53.3 kPa. Use this\ninformation to estimate the enthalpy of vaporization for ethanol.\n"]], ["block_4", [" Answer: \n41,360 J/mol or 41.4 kJ/mol\n"]], ["block_5", [" Estimating Temperature (or Vapor Pressure) \n"]], ["block_6", ["For benzene (C6H6), the normal boiling point is 80.1 \u00b0C and the enthalpy of vaporization is 30.8 kJ/mol. What is\nthe boiling point of benzene in Denver, where atmospheric pressure = 83.4 kPa?\n"]], ["block_7", [" Solution \n"]], ["block_8", ["If the temperature and vapor pressure are known at one point, along with the enthalpy of vaporization, \u0394Hvap,\nthen the temperature that corresponds to a different vapor pressure (or the vapor pressure that corresponds to\na different temperature) can be determined by using the Clausius-Clapeyron equation:\n"]], ["block_9", ["Since the normal boiling point is the temperature at which the vapor pressure equals atmospheric pressure at\nsea level, we know one vapor pressure-temperature value (T1 = 80.1 \u00b0C = 353.3 K, P1 = 101.3 kPa, \u0394Hvap = 30.8\nkJ/mol) and want to find the temperature (T2) that corresponds to vapor pressure P2 = 83.4 kPa. We can\nsubstitute these values into the Clausius-Clapeyron equation and then solve for T2. Rearranging the Clausius-\nClapeyron equation and solving for T2 yields:\n"]], ["block_10", [" Check Your Learning \n"]], ["block_11", ["For acetone (CH3)2CO, the normal boiling point is 56.5 \u00b0C and the enthalpy of vaporization is 31.3 kJ/mol. What\nis the vapor pressure of acetone at 25.0 \u00b0C?\n"]], ["block_12", [" Answer: \n30.1 kPa\n"]], ["block_13", [" Enthalpy of Vaporization \n"]], ["block_14", ["Vaporization is an endothermic process. The cooling effect can be evident when you leave a swimming pool or\n"]], ["block_15", ["EXAMPLE 10.8\n"]], ["block_16", [" 10.3 \u2022 Phase Transitions \n 497 \n"]]], "page_511": [["block_0", [" 498 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", ["a shower. When the water on your skin evaporates, it removes heat from your skin and causes you to feel cold.\nThe energy change associated with the vaporization process is the enthalpy of vaporization, \u0394Hvap. For\nexample, the vaporization of water at standard temperature is represented by:\n"]], ["block_2", ["As described in the chapter on thermochemistry, the reverse of an endothermic process is exothermic. And so,\nthe condensation of a gas releases heat:\n"]], ["block_3", [" Using Enthalpy of Vaporization \n"]], ["block_4", ["One way our body is cooled is by evaporation of the water in sweat (Figure 10.25). In very hot climates, we can\nlose as much as 1.5 L of sweat per day. Although sweat is not pure water, we can get an approximate value of\nthe amount of heat removed by evaporation by assuming that it is. How much heat is required to evaporate 1.5\nL of water (1.5 kg) at T = 37 \u00b0C (normal body temperature); \u0394Hvap = 43.46 kJ/mol at 37 \u00b0C.\n"]], ["block_5", [" Solution \n"]], ["block_6", ["We start with the known volume of sweat (approximated as just water) and use the given information to\nconvert to the amount of heat needed:\n"]], ["block_7", ["Thus, 3600 kJ of heat are removed by the evaporation of 1.5 L of water.\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["How much heat is required to evaporate 100.0 g of liquid ammonia, NH3, at its boiling point if its enthalpy of\nvaporization is 4.8 kJ/mol?\n"]], ["block_10", [" Answer: \n28 kJ\n"]], ["block_11", [" Melting and Freezing \n"]], ["block_12", ["When we heat a crystalline solid, we increase the average energy of its atoms, molecules, or ions and the solid\ngets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the\nmolecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the\nliquid state, or melting . At this point, the temperature of the solid stops rising, despite the continual input of\nheat, and it remains constant until all of the solid is melted. Only after all of the solid has melted will continued\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", ["EXAMPLE 10.9\n"]], ["block_15", [" FIGURE 10.25 \nEvaporation of sweat helps cool the body. (credit: \u201cKullez\u201d/Flickr)\n"]], ["block_16", [{"image_0": "511_0.png", "coords": [189, 275, 423, 430]}]]], "page_512": [["block_0", ["heating increase the temperature of the liquid (Figure 10.26).\n"]], ["block_1", [{"image_0": "512_0.png", "coords": [72, 76, 540, 180]}]], ["block_2", [" FIGURE 10.26 \n(a) This beaker of ice has a temperature of \u221212.0 \u00b0C. (b) After 10 minutes the ice has absorbed\n"]], ["block_3", ["enough heat from the air to warm to 0 \u00b0C. A small amount has melted. (c) Thirty minutes later, the ice has absorbed\nmore heat, but its temperature is still 0 \u00b0C. The ice melts without changing its temperature. (d) Only after all the ice\nhas melted does the heat absorbed cause the temperature to increase to 22.2 \u00b0C. (credit: modification of work by\nMark Ott)\n"]], ["block_4", ["If we stop heating during melting and place the mixture of solid and liquid in a perfectly insulated container so\nno heat can enter or escape, the solid and liquid phases remain in equilibrium. This is almost the situation\nwith a mixture of ice and water in a very good thermos bottle; almost no heat gets in or out, and the mixture of\nsolid ice and liquid water remains for hours. In a mixture of solid and liquid at equilibrium, the reciprocal\nprocesses of melting and freezing occur at equal rates, and the quantities of solid and liquid therefore remain\nconstant. The temperature at which the solid and liquid phases of a given substance are in equilibrium is\ncalled the melting point of the solid or the freezing point of the liquid. Use of one term or the other is normally\ndictated by the direction of the phase transition being considered, for example, solid to liquid (melting) or\nliquid to solid (freezing).\n"]], ["block_5", ["The enthalpy of fusion and the melting point of a crystalline solid depend on the strength of the attractive\nforces between the units present in the crystal. Molecules with weak attractive forces form crystals with low\nmelting points. Crystals consisting of particles with stronger attractive forces melt at higher temperatures.\n"]], ["block_6", ["The amount of heat required to change one mole of a substance from the solid state to the liquid state is the\nenthalpy of fusion, \u0394Hfus of the substance. The enthalpy of fusion of ice is 6.0 kJ/mol at 0 \u00b0C. Fusion (melting) is\nan endothermic process:\n"]], ["block_7", ["The reciprocal process, freezing, is an exothermic process whose enthalpy change is \u22126.0 kJ/mol at 0 \u00b0C:\n"]], ["block_8", [" Sublimation and Deposition \n"]], ["block_9", ["Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as\n sublimation . At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to\ngradually disappear without ever forming any liquid. Snow and ice sublime at temperatures below the melting\npoint of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high\naltitudes. When solid iodine is warmed, the solid sublimes and a vivid purple vapor forms (Figure 10.27). The\nreverse of sublimation is called deposition , a process in which gaseous substances condense directly into the\nsolid state, bypassing the liquid state. The formation of frost is an example of deposition.\n"]], ["block_10", [" 10.3 \u2022 Phase Transitions \n 499 \n"]]], "page_513": [["block_0", [" 500 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [" FIGURE 10.27 \nSublimation of solid iodine in the bottom of the tube produces a purple gas that subsequently\n"]], ["block_2", ["deposits as solid iodine on the colder part of the tube above. (credit: modification of work by Mark Ott)\n"]], ["block_3", ["Like vaporization, the process of sublimation requires an input of energy to overcome intermolecular\nattractions. The enthalpy of sublimation, \u0394Hsub, is the energy required to convert one mole of a substance from\nthe solid to the gaseous state. For example, the sublimation of carbon dioxide is represented by:\n"]], ["block_4", ["Likewise, the enthalpy change for the reverse process of deposition is equal in magnitude but opposite in sign\nto that for sublimation:\n"]], ["block_5", ["Consider the extent to which intermolecular attractions must be overcome to achieve a given phase transition.\nConverting a solid into a liquid requires that these attractions be only partially overcome; transition to the\ngaseous state requires that they be completely overcome. As a result, the enthalpy of fusion for a substance is\nless than its enthalpy of vaporization. This same logic can be used to derive an approximate relation between\nthe enthalpies of all phase changes for a given substance. Though not an entirely accurate description,\nsublimation may be conveniently modeled as a sequential two-step process of melting followed by\nvaporization in order to apply Hess\u2019s Law. Viewed in this manner, the enthalpy of sublimation for a substance\nmay be estimated as the sum of its enthalpies of fusion and vaporization, as illustrated in Figure 10.28. For\nexample:\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [{"image_0": "513_0.png", "coords": [189, 57, 423, 447]}]]], "page_514": [["block_0", [" FIGURE 10.28 \nFor a given substance, the sum of its enthalpy of fusion and enthalpy of vaporization is\n"]], ["block_1", ["approximately equal to its enthalpy of sublimation.\n"]], ["block_2", [" Heating and Cooling Curves \n"]], ["block_3", ["In the chapter on thermochemistry, the relation between the amount of heat absorbed or released by a\nsubstance, q, and its accompanying temperature change, \u0394T, was introduced:\n"]], ["block_4", ["where m is the mass of the substance and c is its specific heat. The relation applies to matter being heated or\ncooled, but not undergoing a change in state. When a substance being heated or cooled reaches a temperature\ncorresponding to one of its phase transitions, further gain or loss of heat is a result of diminishing or\nenhancing intermolecular attractions, instead of increasing or decreasing molecular kinetic energies. While a\nsubstance is undergoing a change in state, its temperature remains constant. Figure 10.29 shows a typical\nheating curve.\n"]], ["block_5", ["Consider the example of heating a pot of water to boiling. A stove burner will supply heat at a roughly constant\nrate; initially, this heat serves to increase the water\u2019s temperature. When the water reaches its boiling point,\nthe temperature remains constant despite the continued input of heat from the stove burner. This same\ntemperature is maintained by the water as long as it is boiling. If the burner setting is increased to provide heat\nat a greater rate, the water temperature does not rise, but instead the boiling becomes more vigorous (rapid).\nThis behavior is observed for other phase transitions as well: For example, temperature remains constant\nwhile the change of state is in progress.\n"]], ["block_6", [{"image_0": "514_0.png", "coords": [189, 110, 423, 285]}]], ["block_7", [" 10.3 \u2022 Phase Transitions \n 501 \n"]]], "page_515": [["block_0", [" 502 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", ["(see previous chapter on thermochemistry). The heat needed to induce a given change in phase is given by q =\nn\n\u0394H.\n"]], ["block_2", [{"image_0": "515_0.png", "coords": [72, 57, 540, 379]}]], ["block_3", [" FIGURE 10.29 \nA typical heating curve for a substance depicts changes in temperature that result as the substance\n"]], ["block_4", ["absorbs increasing amounts of heat. Plateaus in the curve (regions of constant temperature) are exhibited when the\nsubstance undergoes phase transitions.\n"]], ["block_5", [" Total Heat Needed to Change Temperature and Phase for a Substance \n"]], ["block_6", ["How much heat is required to convert 135 g of ice at \u221215 \u00b0C into water vapor at 120 \u00b0C?\n"]], ["block_7", [" Solution \n"]], ["block_8", ["The transition described involves the following steps:\n"]], ["block_9", ["The heat needed to change the temperature of a given substance (with no change in phase) is: q = m\nc\n\u0394T\n"]], ["block_10", ["Using these equations with the appropriate values for specific heat of ice, water, and steam, and enthalpies of\nfusion and vaporization, we have:\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["1.\nHeat ice from \u221215 \u00b0C to 0 \u00b0C\n"]], ["block_13", ["2.\nMelt ice\n"]], ["block_14", ["3.\nHeat water from 0 \u00b0C to 100 \u00b0C\n"]], ["block_15", ["4.\nBoil water\n"]], ["block_16", ["5.\nHeat steam from 100 \u00b0C to 120 \u00b0C\n"]], ["block_17", ["EXAMPLE 10.10\n"]]], "page_516": [["block_0", ["Converting the quantities in J to kJ permits them to be summed, yielding the total heat required:\n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["What is the total amount of heat released when 94.0 g water at 80.0 \u00b0C cools to form ice at \u221230.0 \u00b0C?\n"]], ["block_3", [" Answer: \n68.7 kJ\n"]], ["block_4", [" 10.4 Phase Diagrams \n"]], ["block_5", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_6", ["In the previous module, the variation of a liquid\u2019s equilibrium vapor pressure with temperature was described.\nConsidering the definition of boiling point, plots of vapor pressure versus temperature represent how the\nboiling point of the liquid varies with pressure. Also described was the use of heating and cooling curves to\ndetermine a substance\u2019s melting (or freezing) point. Making such measurements over a wide range of\npressures yields data that may be presented graphically as a phase diagram. A phase diagram combines plots\nof pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a\nsubstance. These diagrams indicate the physical states that exist under specific conditions of pressure and\ntemperature, and also provide the pressure dependence of the phase-transition temperatures (melting points,\nsublimation points, boiling points). A typical phase diagram for a pure substance is shown in Figure 10.30.\n"]], ["block_7", ["\u2022\nExplain the construction and use of a typical phase diagram\n"]], ["block_8", ["\u2022\nUse phase diagrams to identify stable phases at given temperatures and pressures, and to describe phase\ntransitions resulting from changes in these properties\n"]], ["block_9", ["\u2022\nDescribe the supercritical fluid phase of matter\n"]], ["block_10", [" 10.4 \u2022 Phase Diagrams \n 503 \n"]]], "page_517": [["block_0", [" 504 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [" FIGURE 10.30 \nThe physical state of a substance and its phase-transition temperatures are represented\n"]], ["block_2", ["graphically in a phase diagram.\n"]], ["block_3", ["To illustrate the utility of these plots, consider the phase diagram for water shown in Figure 10.31.\n"]], ["block_4", [" FIGURE 10.31 \nThe pressure and temperature axes on this phase diagram of water are not drawn to constant scale\n"]], ["block_5", ["in order to illustrate several important properties.\n"]], ["block_6", ["We can use the phase diagram to identify the physical state of a sample of water under specified conditions of\npressure and temperature. For example, a pressure of 50 kPa and a temperature of \u221210 \u00b0C correspond to the\nregion of the diagram labeled \u201cice.\u201d Under these conditions, water exists only as a solid (ice). A pressure of 50\nkPa and a temperature of 50 \u00b0C correspond to the \u201cwater\u201d region\u2014here, water exists only as a liquid. At 25 kPa\nand 200 \u00b0C, water exists only in the gaseous state. Note that on the H2O phase diagram, the pressure and\ntemperature axes are not drawn to a constant scale in order to permit the illustration of several important\nfeatures as described here.\n"]], ["block_7", ["The curve BC in Figure 10.31 is the plot of vapor pressure versus temperature as described in the previous\nmodule of this chapter. This \u201cliquid-vapor\u201d curve separates the liquid and gaseous regions of the phase\ndiagram and provides the boiling point for water at any pressure. For example, at 1 atm, the boiling point is\n100 \u00b0C. Notice that the liquid-vapor curve terminates at a temperature of 374 \u00b0C and a pressure of 218 atm,\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", [{"image_0": "517_0.png", "coords": [130, 324, 481, 551]}]], ["block_10", [{"image_1": "517_1.png", "coords": [189, 57, 423, 270]}]]], "page_518": [["block_0", ["indicating that water cannot exist as a liquid above this temperature, regardless of the pressure. The physical\nproperties of water under these conditions are intermediate between those of its liquid and gaseous phases.\nThis unique state of matter is called a supercritical fluid, a topic that will be described in the next section of\nthis module.\n"]], ["block_1", ["The solid-vapor curve, labeled AB in Figure 10.31, indicates the temperatures and pressures at which ice and\nwater vapor are in equilibrium. These temperature-pressure data pairs correspond to the sublimation, or\ndeposition, points for water. If we could zoom in on the solid-gas line in Figure 10.31, we would see that ice has\na vapor pressure of about 0.20 kPa at \u221210 \u00b0C. Thus, if we place a frozen sample in a vacuum with a pressure\nless than 0.20 kPa, ice will sublime. This is the basis for the \u201cfreeze-drying\u201d process often used to preserve\nfoods, such as the ice cream shown in Figure 10.32.\n"]], ["block_2", [" FIGURE 10.32 \nFreeze-dried foods, like this ice cream, are dehydrated by sublimation at pressures below the triple\n"]], ["block_3", ["point for water. (credit: \u02balwao\u02ba/Flickr)\n"]], ["block_4", ["The solid-liquid curve labeled BD shows the temperatures and pressures at which ice and liquid water are in\nequilibrium, representing the melting/freezing points for water. Note that this curve exhibits a slight negative\nslope (greatly exaggerated for clarity), indicating that the melting point for water decreases slightly as pressure\nincreases. Water is an unusual substance in this regard, as most substances exhibit an increase in melting\npoint with increasing pressure. This behavior is partly responsible for the movement of glaciers, like the one\nshown in Figure 10.33. The bottom of a glacier experiences an immense pressure due to its weight that can\nmelt some of the ice, forming a layer of liquid water on which the glacier may more easily slide.\n"]], ["block_5", [" FIGURE 10.33 \nThe immense pressures beneath glaciers result in partial melting to produce a layer of water that\n"]], ["block_6", ["provides lubrication to assist glacial movement. This satellite photograph shows the advancing edge of the Perito\nMoreno glacier in Argentina. (credit: NASA)\n"]], ["block_7", ["The point of intersection of all three curves is labeled B in Figure 10.31. At the pressure and temperature\nrepresented by this point, all three phases of water coexist in equilibrium. This temperature-pressure data\n"]], ["block_8", [{"image_0": "518_0.png", "coords": [189, 196, 423, 371]}]], ["block_9", [{"image_1": "518_1.png", "coords": [189, 500, 423, 656]}]], ["block_10", [" 10.4 \u2022 Phase Diagrams \n 505 \n"]]], "page_519": [["block_0", [" 506 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", ["pair is called the triple point . At pressures lower than the triple point, water cannot exist as a liquid, regardless\nof the temperature.\n"]], ["block_2", [" Determining the State of Water \n"]], ["block_3", ["Using the phase diagram for water given in Figure 10.31, determine the state of water at the following\ntemperatures and pressures:\n"]], ["block_4", ["(a) \u221210 \u00b0C and 50 kPa\n"]], ["block_5", ["(b) 25 \u00b0C and 90 kPa\n"]], ["block_6", ["(c) 50 \u00b0C and 40 kPa\n"]], ["block_7", ["(d) 80 \u00b0C and 5 kPa\n"]], ["block_8", ["(e) \u221210 \u00b0C and 0.3 kPa\n"]], ["block_9", ["(f) 50 \u00b0C and 0.3 kPa\n"]], ["block_10", [" Solution \n"]], ["block_11", ["Using the phase diagram for water, we can determine that the state of water at each temperature and pressure\ngiven are as follows: (a) solid; (b) liquid; (c) liquid; (d) gas; (e) solid; (f) gas.\n"]], ["block_12", [" Check Your Learning \n"]], ["block_13", ["What phase changes can water undergo as the temperature changes if the pressure is held at 0.3 kPa? If the\npressure is held at 50 kPa?\n"]], ["block_14", [" Answer: \nAt 0.3 kPa:\nat \u221258 \u00b0C. At 50 kPa:\nat 0 \u00b0C, l \u27f6 g at 78 \u00b0C\n"]], ["block_15", ["Consider the phase diagram for carbon dioxide shown in Figure 10.34 as another example. The solid-liquid\ncurve exhibits a positive slope, indicating that the melting point for CO2 increases with pressure as it does for\nmost substances (water being a notable exception as described previously). Notice that the triple point is well\nabove 1 atm, indicating that carbon dioxide cannot exist as a liquid under ambient pressure conditions.\nInstead, cooling gaseous carbon dioxide at 1 atm results in its deposition into the solid state. Likewise, solid\ncarbon dioxide does not melt at 1 atm pressure but instead sublimes to yield gaseous CO2. Finally, notice that\nthe critical point for carbon dioxide is observed at a relatively modest temperature and pressure in\ncomparison to water.\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["EXAMPLE 10.11\n"]]], "page_520": [["block_0", [" FIGURE 10.34 \nA phase diagram for carbon dioxide is shown. The pressure axis is plotted on a logarithmic scale to\n"]], ["block_1", ["accommodate the large range of values.\n"]], ["block_2", [" Determining the State of Carbon Dioxide \n"]], ["block_3", ["Using the phase diagram for carbon dioxide shown in Figure 10.34, determine the state of CO2 at the following\ntemperatures and pressures:\n"]], ["block_4", ["(a) \u221230 \u00b0C and 2000 kPa\n"]], ["block_5", ["(b) \u221290 \u00b0C and 1000 kPa\n"]], ["block_6", ["(c) \u221260 \u00b0C and 100 kPa\n"]], ["block_7", ["(d) \u221240 \u00b0C and 1500 kPa\n"]], ["block_8", ["(e) 0 \u00b0C and 100 kPa\n"]], ["block_9", ["(f) 20 \u00b0C and 100 kPa\n"]], ["block_10", [" Solution \n"]], ["block_11", ["Using the phase diagram for carbon dioxide provided, we can determine that the state of CO2 at each\ntemperature and pressure given are as follows: (a) liquid; (b) solid; (c) gas; (d) liquid; (e) gas; (f) gas.\n"]], ["block_12", [" Check Your Learning \n"]], ["block_13", ["Identify the phase changes that carbon dioxide will undergo as its temperature is increased from \u2212100 \u00b0C\nwhile holding its pressure constant at 1500 kPa. At 50 kPa. At what approximate temperatures do these phase\nchanges occur?\n"]], ["block_14", [" Answer: \nat 1500 kPa:\nat \u221255 \u00b0C,\nat \u221210 \u00b0C;\n"]], ["block_15", ["at 50 kPa:\nat \u221260 \u00b0C\n"]], ["block_16", [" Supercritical Fluids \n"]], ["block_17", ["If we place a sample of water in a sealed container at 25 \u00b0C, remove the air, and let the vaporization-\ncondensation equilibrium establish itself, we are left with a mixture of liquid water and water vapor at a\npressure of 0.03 atm. A distinct boundary between the more dense liquid and the less dense gas is clearly\n"]], ["block_18", ["EXAMPLE 10.12\n"]], ["block_19", [{"image_0": "520_0.png", "coords": [130, 57, 481, 271]}]], ["block_20", [" 10.4 \u2022 Phase Diagrams \n 507 \n"]]], "page_521": [["block_0", [" 508 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", ["observed. As we increase the temperature, the pressure of the water vapor increases, as described by the\nliquid-gas curve in the phase diagram for water (Figure 10.31), and a two-phase equilibrium of liquid and\ngaseous phases remains. At a temperature of 374 \u00b0C, the vapor pressure has risen to 218 atm, and any further\nincrease in temperature results in the disappearance of the boundary between liquid and vapor phases. All of\nthe water in the container is now present in a single phase whose physical properties are intermediate\nbetween those of the gaseous and liquid states. This phase of matter is called a supercritical fluid , and the\ntemperature and pressure above which this phase exists is the critical point (Figure 10.35). Above its critical\ntemperature, a gas cannot be liquefied no matter how much pressure is applied. The pressure required to\nliquefy a gas at its critical temperature is called the critical pressure. The critical temperatures and critical\npressures of some common substances are given in the following table.\n"]], ["block_2", [{"image_0": "521_0.png", "coords": [72, 407, 540, 517]}]], ["block_3", [" FIGURE 10.35 \n(a) A sealed container of liquid carbon dioxide slightly below its critical point is heated, resulting in\n"]], ["block_4", ["(b) the formation of the supercritical fluid phase. Cooling the supercritical fluid lowers its temperature and pressure\nbelow the critical point, resulting in the reestablishment of separate liquid and gaseous phases (c and d). Colored\nfloats illustrate differences in density between the liquid, gaseous, and supercritical fluid states. (credit:\nmodification of work by \u201cmrmrobin\u201d/YouTube)\n"]], ["block_5", ["Observe the liquid-to-supercritical fluid transition (http://openstax.org/l/16supercrit) for carbon dioxide.\n"]], ["block_6", ["Like a gas, a supercritical fluid will expand and fill a container, but its density is much greater than typical gas\ndensities, typically being close to those for liquids. Similar to liquids, these fluids are capable of dissolving\nnonvolatile solutes. They exhibit essentially no surface tension and very low viscosities, however, so they can\nmore effectively penetrate very small openings in a solid mixture and remove soluble components. These\nproperties make supercritical fluids extremely useful solvents for a wide range of applications. For example,\nsupercritical carbon dioxide has become a very popular solvent in the food industry, being used to\ndecaffeinate coffee, remove fats from potato chips, and extract flavor and fragrance compounds from citrus\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", ["LINK TO LEARNING\n"]], ["block_9", [" Substance \n Critical Temperature (\u00b0C) \n Critical Pressure (kPa) \n"]], ["block_10", ["hydrogen\n\u2212240.0\n1300\n"]], ["block_11", ["nitrogen\n\u2212147.2\n3400\n"]], ["block_12", ["oxygen\n\u2212118.9\n5000\n"]], ["block_13", ["carbon dioxide\n31.1\n7400\n"]], ["block_14", ["ammonia\n132.4\n11,300\n"]], ["block_15", ["sulfur dioxide\n157.2\n7800\n"]], ["block_16", ["water\n374.0\n22,000\n"]]], "page_522": [["block_0", ["oils. It is nontoxic, relatively inexpensive, and not considered to be a pollutant. After use, the CO2 can be easily\nrecovered by reducing the pressure and collecting the resulting gas.\n"]], ["block_1", [" The Critical Temperature of Carbon Dioxide \n"]], ["block_2", ["If we shake a carbon dioxide fire extinguisher on a cool day (18 \u00b0C), we can hear liquid CO2 sloshing around\ninside the cylinder. However, the same cylinder appears to contain no liquid on a hot summer day (35 \u00b0C).\nExplain these observations.\n"]], ["block_3", [" Solution \n"]], ["block_4", ["On the cool day, the temperature of the CO2 is below the critical temperature of CO2, 304 K or 31 \u00b0C, so liquid\nCO2 is present in the cylinder. On the hot day, the temperature of the CO2 is greater than its critical\ntemperature of 31 \u00b0C. Above this temperature no amount of pressure can liquefy CO2 so no liquid CO2 exists in\nthe fire extinguisher.\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["Ammonia can be liquefied by compression at room temperature; oxygen cannot be liquefied under these\nconditions. Why do the two gases exhibit different behavior?\n"]], ["block_7", [" Answer: \nThe critical temperature of ammonia is 405.5 K, which is higher than room temperature. The critical\ntemperature of oxygen is below room temperature; thus oxygen cannot be liquefied at room temperature.\n"]], ["block_8", ["Chemistry in Everyday Life\n"]], ["block_9", [" Decaffeinating Coffee Using Supercritical CO 2 \nCoffee is the world\u2019s second most widely traded commodity, following only petroleum. Across the globe,\npeople love coffee\u2019s aroma and taste. Many of us also depend on one component of coffee\u2014caffeine\u2014to help\nus get going in the morning or stay alert in the afternoon. But late in the day, coffee\u2019s stimulant effect can\nkeep you from sleeping, so you may choose to drink decaffeinated coffee in the evening.\n"]], ["block_10", ["Since the early 1900s, many methods have been used to decaffeinate coffee. All have advantages and\ndisadvantages, and all depend on the physical and chemical properties of caffeine. Because caffeine is a\nsomewhat polar molecule, it dissolves well in water, a polar liquid. However, since many of the other\n400-plus compounds that contribute to coffee\u2019s taste and aroma also dissolve in H2O, hot water\ndecaffeination processes can also remove some of these compounds, adversely affecting the smell and\ntaste of the decaffeinated coffee. Dichloromethane (CH2Cl2) and ethyl acetate (CH3CO2C2H5) have similar\npolarity to caffeine, and are therefore very effective solvents for caffeine extraction, but both also remove\nsome flavor and aroma components, and their use requires long extraction and cleanup times. Because\nboth of these solvents are toxic, health concerns have been raised regarding the effect of residual solvent\nremaining in the decaffeinated coffee.\n"]], ["block_11", ["Supercritical fluid extraction using carbon dioxide is now being widely used as a more effective and\nenvironmentally friendly decaffeination method (Figure 10.36). At temperatures above 304.2 K and\npressures above 7376 kPa, CO2 is a supercritical fluid, with properties of both gas and liquid. Like a gas, it\npenetrates deep into the coffee beans; like a liquid, it effectively dissolves certain substances. Supercritical\ncarbon dioxide extraction of steamed coffee beans removes 97\u221299% of the caffeine, leaving coffee\u2019s flavor\nand aroma compounds intact. Because CO2 is a gas under standard conditions, its removal from the\nextracted coffee beans is easily accomplished, as is the recovery of the caffeine from the extract. The\ncaffeine recovered from coffee beans via this process is a valuable product that can be used subsequently\nas an additive to other foods or drugs.\n"]], ["block_12", ["EXAMPLE 10.13\n"]], ["block_13", [" 10.4 \u2022 Phase Diagrams \n 509 \n"]]], "page_523": [["block_0", [" 510 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [" 10.5 The Solid State of Matter \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["When most liquids are cooled, they eventually freeze and form crystalline solids , solids in which the atoms,\nions, or molecules are arranged in a definite repeating pattern. It is also possible for a liquid to freeze before its\nmolecules become arranged in an orderly pattern. The resulting materials are called amorphous solids or\nnoncrystalline solids (or, sometimes, glasses). The particles of such solids lack an ordered internal structure\nand are randomly arranged (Figure 10.37).\n"]], ["block_4", [" FIGURE 10.37 \nThe entities of a solid phase may be arranged in a regular, repeating pattern (crystalline solids) or\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", ["\u2022\nDefine and describe the bonding and properties of ionic, molecular, metallic, and covalent network crystalline\nsolids\n"]], ["block_7", ["\u2022\nDescribe the main types of crystalline solids: ionic solids, metallic solids, covalent network solids, and\nmolecular solids\n"]], ["block_8", ["\u2022\nExplain the ways in which crystal defects can occur in a solid\n"]], ["block_9", [" FIGURE 10.36 \n(a) Caffeine molecules have both polar and nonpolar regions, making it soluble in solvents of\n"]], ["block_10", ["varying polarities. (b) The schematic shows a typical decaffeination process involving supercritical carbon\ndioxide.\n"]], ["block_11", [{"image_0": "523_0.png", "coords": [90, 57, 522, 349]}]], ["block_12", [{"image_1": "523_1.png", "coords": [196, 607, 415, 710]}]]], "page_524": [["block_0", [" Metallic solids such as crystals of copper, aluminum, and iron are formed by metal atoms Figure 10.40. The\nstructure of metallic crystals is often described as a uniform distribution of atomic nuclei within a \u201csea\u201d of\ndelocalized electrons. The atoms within such a metallic solid are held together by a unique force known as\nmetallic bonding that gives rise to many useful and varied bulk properties. All exhibit high thermal and\nelectrical conductivity, metallic luster, and malleability. Many are very hard and quite strong. Because of their\n"]], ["block_1", ["randomly (amorphous).\n"]], ["block_2", ["Metals and ionic compounds typically form ordered, crystalline solids. Substances that consist of large\nmolecules, or a mixture of molecules whose movements are more restricted, often form amorphous solids. For\nexamples, candle waxes are amorphous solids composed of large hydrocarbon molecules. Some substances,\nsuch as silicon dioxide (shown in Figure 10.38), can form either crystalline or amorphous solids, depending on\nthe conditions under which it is produced. Also, amorphous solids may undergo a transition to the crystalline\nstate under appropriate conditions.\n"]], ["block_3", [" FIGURE 10.38 \n(a) Silicon dioxide, SiO2, is abundant in nature as one of several crystalline forms of the mineral\n"]], ["block_4", ["quartz. (b) Rapid cooling of molten SiO2 yields an amorphous solid known as \u201cfused silica\u201d.\n"]], ["block_5", ["Crystalline solids are generally classified according to the nature of the forces that hold its particles together.\nThese forces are primarily responsible for the physical properties exhibited by the bulk solids. The following\nsections provide descriptions of the major types of crystalline solids: ionic, metallic, covalent network, and\nmolecular.\n"]], ["block_6", [" Ionic Solids \n"]], ["block_7", [" Ionic solids , such as sodium chloride and nickel oxide, are composed of positive and negative ions that are\nheld together by electrostatic attractions, which can be quite strong (Figure 10.39). Many ionic crystals also\nhave high melting points. This is due to the very strong attractions between the ions\u2014in ionic compounds, the\nattractions between full charges are (much) larger than those between the partial charges in polar molecular\ncompounds. This will be looked at in more detail in a later discussion of lattice energies. Although they are\nhard, they also tend to be brittle, and they shatter rather than bend. Ionic solids do not conduct electricity;\nhowever, they do conduct when molten or dissolved because their ions are free to move. Many simple\ncompounds formed by the reaction of a metallic element with a nonmetallic element are ionic.\n"]], ["block_8", [" Metallic Solids \n"]], ["block_9", [{"image_0": "524_0.png", "coords": [75, 158, 536, 334]}]], ["block_10", [" FIGURE 10.39 \nSodium chloride is an ionic solid.\n"]], ["block_11", [{"image_1": "524_1.png", "coords": [268, 552, 343, 625]}]], ["block_12", [" 10.5 \u2022 The Solid State of Matter \n 511 \n"]]], "page_525": [["block_0", [" 512 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", ["malleability (the ability to deform under pressure or hammering), they do not shatter and, therefore, make\nuseful construction materials. The melting points of the metals vary widely. Mercury is a liquid at room\ntemperature, and the alkali metals melt below 200 \u00b0C. Several post-transition metals also have low melting\npoints, whereas the transition metals melt at temperatures above 1000 \u00b0C. These differences reflect\ndifferences in strengths of metallic bonding among the metals.\n"]], ["block_2", [" Covalent Network Solid \n"]], ["block_3", [" Covalent network solids include crystals of diamond, silicon, some other nonmetals, and some covalent\ncompounds such as silicon dioxide (sand) and silicon carbide (carborundum, the abrasive on sandpaper).\nMany minerals have networks of covalent bonds. The atoms in these solids are held together by a network of\ncovalent bonds, as shown in Figure 10.41. To break or to melt a covalent network solid, covalent bonds must be\nbroken. Because covalent bonds are relatively strong, covalent network solids are typically characterized by\nhardness, strength, and high melting points. For example, diamond is one of the hardest substances known\nand melts above 3500 \u00b0C.\n"]], ["block_4", [{"image_0": "525_0.png", "coords": [72, 349, 540, 568]}]], ["block_5", [" FIGURE 10.41 \nA covalent crystal contains a three-dimensional network of covalent bonds, as illustrated by the\n"]], ["block_6", ["structures of diamond, silicon dioxide, silicon carbide, and graphite. Graphite is an exceptional example, composed\nof planar sheets of covalent crystals that are held together in layers by noncovalent forces. Unlike typical covalent\nsolids, graphite is very soft and electrically conductive.\n"]], ["block_7", [" Molecular Solid \n"]], ["block_8", [" Molecular solids , such as ice, sucrose (table sugar), and iodine, as shown in Figure 10.42, are composed of\nneutral molecules. The strengths of the attractive forces between the units present in different crystals vary\nwidely, as indicated by the melting points of the crystals. Small symmetrical molecules (nonpolar molecules),\nsuch as H2, N2, O2, and F2, have weak attractive forces and form molecular solids with very low melting points\n(below \u2212200 \u00b0C). Substances consisting of larger, nonpolar molecules have larger attractive forces and melt at\nhigher temperatures. Molecular solids composed of molecules with permanent dipole moments (polar\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", [" FIGURE 10.40 \nCopper is a metallic solid.\n"]], ["block_11", [{"image_1": "525_1.png", "coords": [262, 126, 349, 213]}]]], "page_526": [["block_0", ["molecules) melt at still higher temperatures. Examples include ice (melting point, 0 \u00b0C) and table sugar\n(melting point, 185 \u00b0C).\n"]], ["block_1", [" FIGURE 10.42 \nCarbon dioxide (CO2) consists of small, nonpolar molecules and forms a molecular solid with a\n"]], ["block_2", ["melting point of \u221278 \u00b0C. Iodine (I2) consists of larger, nonpolar molecules and forms a molecular solid that melts at\n114 \u00b0C.\n"]], ["block_3", [" Properties of Solids \n"]], ["block_4", ["A crystalline solid, like those listed in Table 10.4, has a precise melting temperature because each atom or\nmolecule of the same type is held in place with the same forces or energy. Thus, the attractions between the\nunits that make up the crystal all have the same strength and all require the same amount of energy to be\nbroken. The gradual softening of an amorphous material differs dramatically from the distinct melting of a\ncrystalline solid. This results from the structural nonequivalence of the molecules in the amorphous solid.\nSome forces are weaker than others, and when an amorphous material is heated, the weakest intermolecular\nattractions break first. As the temperature is increased further, the stronger attractions are broken. Thus\namorphous materials soften over a range of temperatures.\n"]], ["block_5", [" TABLE 10.4 \n"]], ["block_6", [" Type of \n Solid \n"]], ["block_7", ["ionic\nions\nionic\nbonds\n"]], ["block_8", ["metallic\n"]], ["block_9", ["covalent\nnetwork\n"]], ["block_10", ["molecular\nmolecules (or\natoms)\nIMFs\nvariable hardness, variable brittleness, not\nconductive, low melting points\n"]], ["block_11", [" Type of \n Particles \n"]], ["block_12", ["atoms of\nelectropositive\nelements\n"]], ["block_13", ["atoms of\nelectronegative\nelements\n"]], ["block_14", [{"image_0": "526_0.png", "coords": [189, 89, 423, 208]}]], ["block_15", ["Types of Crystalline Solids and Their Properties\n"]], ["block_16", [" Type of \n Attractions \n Properties \n Examples \n"]], ["block_17", ["metallic\nbonds\n"]], ["block_18", ["covalent\nbonds\n"]], ["block_19", ["hard, brittle, conducts electricity as a liquid but\nnot as a solid, high to very high melting points\n"]], ["block_20", ["shiny, malleable, ductile, conducts heat and\nelectricity well, variable hardness and melting\ntemperature\n"]], ["block_21", ["very hard, not conductive, very high melting\npoints\n"]], ["block_22", [" 10.5 \u2022 The Solid State of Matter \n 513 \n"]], ["block_23", ["NaCl,\nAl2O3\n"]], ["block_24", ["Cu, Fe, Ti,\nPb, U\n"]], ["block_25", ["C\n(diamond),\nSiO2, SiC\n"]], ["block_26", ["H2O, CO2,\nI2,\nC12H22O11\n"]]], "page_527": [["block_0", [" 514 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [" Graphene: Material of the Future \nCarbon is an essential element in our world. The unique properties of carbon atoms allow the existence of\ncarbon-based life forms such as ourselves. Carbon forms a huge variety of substances that we use on a daily\nbasis, including those shown in Figure 10.43. You may be familiar with diamond and graphite, the two most\ncommon allotropes of carbon. (Allotropes are different structural forms of the same element.) Diamond is one\nof the hardest-known substances, whereas graphite is soft enough to be used as pencil lead. These very\ndifferent properties stem from the different arrangements of the carbon atoms in the different allotropes.\n"]], ["block_2", [" FIGURE 10.43 \nDiamond is extremely hard because of the strong bonding between carbon atoms in all directions.\n"]], ["block_3", ["Graphite (in pencil lead) rubs off onto paper due to the weak attractions between the carbon layers. An image of a\ngraphite surface shows the distance between the centers of adjacent carbon atoms. (credit left photo: modification\nof work by Steve Jurvetson; credit middle photo: modification of work by United States Geological Survey)\n"]], ["block_4", ["You may be less familiar with a recently discovered form of carbon: graphene. Graphene was first isolated in\n2004 by using tape to peel off thinner and thinner layers from graphite. It is essentially a single sheet (one\natom thick) of graphite. Graphene, illustrated in Figure 10.44, is not only strong and lightweight, but it is also\nan excellent conductor of electricity and heat. These properties may prove very useful in a wide range of\napplications, such as vastly improved computer chips and circuits, better batteries and solar cells, and\nstronger and lighter structural materials. The 2010 Nobel Prize in Physics was awarded to Andre Geim and\nKonstantin Novoselov for their pioneering work with graphene.\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", [{"image_0": "527_0.png", "coords": [90, 186, 522, 430]}]], ["block_7", ["HOW SCIENCES INTERCONNECT\n"]]], "page_528": [["block_0", [" Crystal Defects \n"]], ["block_1", ["In a crystalline solid, the atoms, ions, or molecules are arranged in a definite repeating pattern, but occasional\ndefects may occur in the pattern. Several types of defects are known, as illustrated in Figure 10.45. Vacancies \nare defects that occur when positions that should contain atoms or ions are vacant. Less commonly, some\natoms or ions in a crystal may occupy positions, called interstitial sites , located between the regular positions\nfor atoms. Other distortions are found in impure crystals, as, for example, when the cations, anions, or\nmolecules of the impurity are too large to fit into the regular positions without distorting the structure. Trace\namounts of impurities are sometimes added to a crystal (a process known as doping) in order to create defects\nin the structure that yield desirable changes in its properties. For example, silicon crystals are doped with\nvarying amounts of different elements to yield suitable electrical properties for their use in the manufacture of\nsemiconductors and computer chips.\n"]], ["block_2", [{"image_0": "528_0.png", "coords": [104, 57, 507, 361]}]], ["block_3", [" FIGURE 10.44 \nGraphene sheets can be formed into buckyballs, nanotubes, and stacked layers.\n"]], ["block_4", [" 10.5 \u2022 The Solid State of Matter \n 515 \n"]]], "page_529": [["block_0", [" 516 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [" 10.6 Lattice Structures in Crystalline Solids \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["Over 90% of naturally occurring and man-made solids are crystalline. Most solids form with a regular\narrangement of their particles because the overall attractive interactions between particles are maximized,\nand the total intermolecular energy is minimized, when the particles pack in the most efficient manner. The\nregular arrangement at an atomic level is often reflected at a macroscopic level. In this module, we will explore\nsome of the details about the structures of metallic and ionic crystalline solids, and learn how these structures\nare determined experimentally.\n"]], ["block_4", [" The Structures of Metals \n"]], ["block_5", ["We will begin our discussion of crystalline solids by considering elemental metals, which are relatively simple\nbecause each contains only one type of atom. A pure metal is a crystalline solid with metal atoms packed\nclosely together in a repeating pattern. Some of the properties of metals in general, such as their malleability\nand ductility, are largely due to having identical atoms arranged in a regular pattern. The different properties\nof one metal compared to another partially depend on the sizes of their atoms and the specifics of their spatial\narrangements. We will explore the similarities and differences of four of the most common metal crystal\ngeometries in the sections that follow.\n"]], ["block_6", [" Unit Cells of Metals \n"]], ["block_7", ["The structure of a crystalline solid, whether a metal or not, is best described by considering its simplest\nrepeating unit, which is referred to as its unit cell . The unit cell consists of lattice points that represent the\nlocations of atoms or ions. The entire structure then consists of this unit cell repeating in three dimensions, as\nillustrated in Figure 10.46.\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["\u2022\nDescribe the arrangement of atoms and ions in crystalline structures\n"]], ["block_10", ["\u2022\nCompute ionic radii using unit cell dimensions\n"]], ["block_11", ["\u2022\nExplain the use of X-ray diffraction measurements in determining crystalline structures\n"]], ["block_12", [" FIGURE 10.45 \nTypes of crystal defects include vacancies, interstitial atoms, and substitutions impurities.\n"]], ["block_13", [{"image_0": "529_0.png", "coords": [189, 57, 423, 229]}]]], "page_530": [["block_0", ["Let us begin our investigation of crystal lattice structure and unit cells with the most straightforward structure\nand the most basic unit cell. To visualize this, imagine taking a large number of identical spheres, such as\ntennis balls, and arranging them uniformly in a container. The simplest way to do this would be to make layers\nin which the spheres in one layer are directly above those in the layer below, as illustrated in Figure 10.47. This\narrangement is called simple cubic structure , and the unit cell is called the simple cubic unit cell or\nprimitive cubic unit cell.\n"]], ["block_1", [{"image_0": "530_0.png", "coords": [72, 274, 540, 388]}]], ["block_2", [" FIGURE 10.47 \nWhen metal atoms are arranged with spheres in one layer directly above or below spheres in\n"]], ["block_3", ["another layer, the lattice structure is called simple cubic. Note that the spheres are in contact.\n"]], ["block_4", ["In a simple cubic structure, the spheres are not packed as closely as they could be, and they only \u201cfill\u201d about\n52% of the volume of the container. This is a relatively inefficient arrangement, and only one metal (polonium,\nPo) crystallizes in a simple cubic structure. As shown in Figure 10.48, a solid with this type of arrangement\nconsists of planes (or layers) in which each atom contacts only the four nearest neighbors in its layer; one atom\ndirectly above it in the layer above; and one atom directly below it in the layer below. The number of other\nparticles that each particle in a crystalline solid contacts is known as its coordination number . For a\npolonium atom in a simple cubic array, the coordination number is, therefore, six.\n"]], ["block_5", [" FIGURE 10.48 \nAn atom in a simple cubic lattice structure contacts six other atoms, so it has a coordination\n"]], ["block_6", ["number of six.\n"]], ["block_7", ["In a simple cubic lattice, the unit cell that repeats in all directions is a cube defined by the centers of eight\natoms, as shown in Figure 10.49. Atoms at adjacent corners of this unit cell contact each other, so the edge\nlength of this cell is equal to two atomic radii, or one atomic diameter. A cubic unit cell contains only the parts\nof these atoms that are within it. Since an atom at a corner of a simple cubic unit cell is contained by a total of\neight unit cells, only one-eighth of that atom is within a specific unit cell. And since each simple cubic unit cell\nhas one atom at each of its eight \u201ccorners,\u201d there is\natom within one simple cubic unit cell.\n"]], ["block_8", [" FIGURE 10.46 \nA unit cell shows the locations of lattice points repeating in all directions.\n"]], ["block_9", [{"image_1": "530_1.png", "coords": [189, 57, 423, 170]}]], ["block_10", [{"image_2": "530_2.png", "coords": [189, 517, 423, 618]}]], ["block_11", [" 10.6 \u2022 Lattice Structures in Crystalline Solids \n 517 \n"]]], "page_531": [["block_0", [" 518 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [" FIGURE 10.49 \nA simple cubic lattice unit cell contains one-eighth of an atom at each of its eight corners, so it\n"]], ["block_2", ["contains one atom total.\n"]], ["block_3", [" Calculation of Atomic Radius and Density for Metals, Part 1 \n"]], ["block_4", ["The edge length of the unit cell of alpha polonium is 336 pm.\n"]], ["block_5", ["(a) Determine the radius of a polonium atom.\n"]], ["block_6", ["(b) Determine the density of alpha polonium.\n"]], ["block_7", [" Solution \n"]], ["block_8", ["Alpha polonium crystallizes in a simple cubic unit cell:\n"]], ["block_9", [{"image_0": "531_0.png", "coords": [72, 360, 189, 482]}]], ["block_10", ["(a) Two adjacent Po atoms contact each other, so the edge length of this cell is equal to two Po atomic radii: l =\n"]], ["block_11", ["2r. Therefore, the radius of Po is\n"]], ["block_12", ["(b) Density is given by\nThe density of polonium can be found by determining the density of\n"]], ["block_13", ["its unit cell (the mass contained within a unit cell divided by the volume of the unit cell). Since a Po unit cell\ncontains one-eighth of a Po atom at each of its eight corners, a unit cell contains one Po atom.\n"]], ["block_14", ["The mass of a Po unit cell can be found by:\n"]], ["block_15", ["The volume of a Po unit cell can be found by:\n"]], ["block_16", ["(Note that the edge length was converted from pm to cm to get the usual volume units for density.)\n"]], ["block_17", ["Therefore, the density of\n"]], ["block_18", [" Access for free at openstax.org \n"]], ["block_19", ["EXAMPLE 10.14\n"]], ["block_20", [{"image_1": "531_1.png", "coords": [189, 57, 423, 186]}]]], "page_532": [["block_0", [" Check Your Learning \n"]], ["block_1", ["The edge length of the unit cell for nickel is 0.3524 nm. The density of Ni is 8.90 g/cm. Does nickel crystallize\nin a simple cubic structure? Explain.\n"]], ["block_2", [" Answer: \nNo. If Ni was simple cubic, its density would be given by:\n"]], ["block_3", ["Then the density of Ni would be\n"]], ["block_4", ["Since the actual density of Ni is not close to this, Ni does not form a simple cubic structure.\n"]], ["block_5", ["Most metal crystals are one of the four major types of unit cells. For now, we will focus on the three cubic unit\ncells: simple cubic (which we have already seen), body-centered cubic unit cell , and face-centered cubic unit \n cell \u2014all of which are illustrated in Figure 10.50. (Note that there are actually seven different lattice systems,\nsome of which have more than one type of lattice, for a total of 14 different types of unit cells. We leave the\nmore complicated geometries for later in this module.)\n"]], ["block_6", [{"image_0": "532_0.png", "coords": [72, 293, 540, 584]}]], ["block_7", [" FIGURE 10.50 \nCubic unit cells of metals show (in the upper figures) the locations of lattice points and (in the lower\n"]], ["block_8", ["figures) metal atoms located in the unit cell.\n"]], ["block_9", ["Some metals crystallize in an arrangement that has a cubic unit cell with atoms at all of the corners and an\natom in the center, as shown in Figure 10.51. This is called a body-centered cubic (BCC) solid . Atoms in the\ncorners of a BCC unit cell do not contact each other but contact the atom in the center. A BCC unit cell contains\ntwo atoms: one-eighth of an atom at each of the eight corners\natom from the corners) plus one\n"]], ["block_10", ["atom from the center. Any atom in this structure touches four atoms in the layer above it and four atoms in the\nlayer below it. Thus, an atom in a BCC structure has a coordination number of eight.\n"]], ["block_11", [" 10.6 \u2022 Lattice Structures in Crystalline Solids \n 519 \n"]]], "page_533": [["block_0", [" 520 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [" FIGURE 10.51 \nIn a body-centered cubic structure, atoms in a specific layer do not touch each other. Each atom\n"]], ["block_2", ["touches four atoms in the layer above it and four atoms in the layer below it.\n"]], ["block_3", ["Atoms in BCC arrangements are much more efficiently packed than in a simple cubic structure, occupying\nabout 68% of the total volume. Isomorphous metals with a BCC structure include K, Ba, Cr, Mo, W, and Fe at\nroom temperature. (Elements or compounds that crystallize with the same structure are said to be\n isomorphous .)\n"]], ["block_4", ["Many other metals, such as aluminum, copper, and lead, crystallize in an arrangement that has a cubic unit\ncell with atoms at all of the corners and at the centers of each face, as illustrated in Figure 10.52. This\narrangement is called a face-centered cubic (FCC) solid . A FCC unit cell contains four atoms: one-eighth of an\natom at each of the eight corners\natom from the corners) and one-half of an atom on each of the\n"]], ["block_5", ["six faces\natoms from the faces). The atoms at the corners touch the atoms in the centers of the\n"]], ["block_6", ["adjacent faces along the face diagonals of the cube. Because the atoms are on identical lattice points, they have\nidentical environments.\n"]], ["block_7", [" FIGURE 10.52 \nA face-centered cubic solid has atoms at the corners and, as the name implies, at the centers of the\n"]], ["block_8", ["faces of its unit cells.\n"]], ["block_9", ["Atoms in an FCC arrangement are packed as closely together as possible, with atoms occupying 74% of the\nvolume. This structure is also called cubic closest packing (CCP) . In CCP, there are three repeating layers of\nhexagonally arranged atoms. Each atom contacts six atoms in its own layer, three in the layer above, and three\nin the layer below. In this arrangement, each atom touches 12 near neighbors, and therefore has a\ncoordination number of 12. The fact that FCC and CCP arrangements are equivalent may not be immediately\nobvious, but why they are actually the same structure is illustrated in Figure 10.53.\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [{"image_0": "533_0.png", "coords": [130, 57, 481, 185]}]], ["block_12", [{"image_1": "533_1.png", "coords": [130, 376, 481, 504]}]]], "page_534": [["block_0", [" FIGURE 10.53 \nA CCP arrangement consists of three repeating layers (ABCABC\u2026) of hexagonally arranged atoms.\n"]], ["block_1", ["Atoms in a CCP structure have a coordination number of 12 because they contact six atoms in their layer, plus three\natoms in the layer above and three atoms in the layer below. By rotating our perspective, we can see that a CCP\nstructure has a unit cell with a face containing an atom from layer A at one corner, atoms from layer B across a\ndiagonal (at two corners and in the middle of the face), and an atom from layer C at the remaining corner. This is the\nsame as a face-centered cubic arrangement.\n"]], ["block_2", ["Because closer packing maximizes the overall attractions between atoms and minimizes the total\nintermolecular energy, the atoms in most metals pack in this manner. We find two types of closest packing in\nsimple metallic crystalline structures: CCP, which we have already encountered, and hexagonal closest \n packing (HCP) shown in Figure 10.54. Both consist of repeating layers of hexagonally arranged atoms. In both\ntypes, a second layer (B) is placed on the first layer (A) so that each atom in the second layer is in contact with\nthree atoms in the first layer. The third layer is positioned in one of two ways. In HCP, atoms in the third layer\nare directly above atoms in the first layer (i.e., the third layer is also type A), and the stacking consists of\nalternating type A and type B close-packed layers (i.e., ABABAB\u22ef). In CCP, atoms in the third layer are not\nabove atoms in either of the first two layers (i.e., the third layer is type C), and the stacking consists of\nalternating type A, type B, and type C close-packed layers (i.e., ABCABCABC\u22ef). About two\u2013thirds of all metals\ncrystallize in closest-packed arrays with coordination numbers of 12. Metals that crystallize in an HCP\nstructure include Cd, Co, Li, Mg, Na, and Zn, and metals that crystallize in a CCP structure include Ag, Al, Ca,\nCu, Ni, Pb, and Pt.\n"]], ["block_3", [" FIGURE 10.54 \nIn both types of closest packing, atoms are packed as compactly as possible. Hexagonal closest\n"]], ["block_4", ["packing consists of two alternating layers (ABABAB\u2026). Cubic closest packing consists of three alternating layers\n(ABCABCABC\u2026).\n"]], ["block_5", [{"image_0": "534_0.png", "coords": [124, 57, 487, 213]}]], ["block_6", [{"image_1": "534_1.png", "coords": [145, 468, 466, 640]}]], ["block_7", [" 10.6 \u2022 Lattice Structures in Crystalline Solids \n 521 \n"]]], "page_535": [["block_0", [" 522 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [" Calculation of Atomic Radius and Density for Metals, Part 2 \n"]], ["block_2", ["Calcium crystallizes in a face-centered cubic structure. The edge length of its unit cell is 558.8 pm.\n"]], ["block_3", ["(a) What is the atomic radius of Ca in this structure?\n"]], ["block_4", ["(b) Calculate the density of Ca.\n"]], ["block_5", [" Solution \n"]], ["block_6", [{"image_0": "535_0.png", "coords": [72, 182, 189, 299]}]], ["block_7", ["(a) In an FCC structure, Ca atoms contact each other across the diagonal of the face, so the length of the\ndiagonal is equal to four Ca atomic radii (d = 4r). Two adjacent edges and the diagonal of the face form a right\ntriangle, with the length of each side equal to 558.8 pm and the length of the hypotenuse equal to four Ca\natomic radii:\n"]], ["block_8", ["Solving this gives\n"]], ["block_9", ["(b) Density is given by\nThe density of calcium can be found by determining the density of its\n"]], ["block_10", ["unit cell: for example, the mass contained within a unit cell divided by the volume of the unit cell. A face-\ncentered Ca unit cell has one-eighth of an atom at each of the eight corners\natom) and one-half of\n"]], ["block_11", ["an atom on each of the six faces\natoms), for a total of four atoms in the unit cell.\n"]], ["block_12", ["The mass of the unit cell can be found by:\n"]], ["block_13", ["The volume of a Ca unit cell can be found by:\n"]], ["block_14", ["(Note that the edge length was converted from pm to cm to get the usual volume units for density.)\n"]], ["block_15", ["Then, the density of\n"]], ["block_16", [" Check Your Learning \n"]], ["block_17", ["Silver crystallizes in an FCC structure. The edge length of its unit cell is 409 pm.\n"]], ["block_18", ["(a) What is the atomic radius of Ag in this structure?\n"]], ["block_19", ["(b) Calculate the density of Ag.\n"]], ["block_20", [" Answer: \n(a) 144 pm; (b) 10.5 g/cm\n"]], ["block_21", [" Access for free at openstax.org \n"]], ["block_22", ["EXAMPLE 10.15\n"]]], "page_536": [["block_0", ["In general, a unit cell is defined by the lengths of three axes (a, b, and c) and the angles (\u03b1, \u03b2, and \u03b3) between\nthem, as illustrated in Figure 10.55. The axes are defined as being the lengths between points in the space\nlattice. Consequently, unit cell axes join points with identical environments.\n"]], ["block_1", [" FIGURE 10.55 \nA unit cell is defined by the lengths of its three axes (a, b, and c) and the angles (\u03b1, \u03b2, and \u03b3)\n"]], ["block_2", ["between the axes.\n"]], ["block_3", ["There are seven different lattice systems, some of which have more than one type of lattice, for a total of\nfourteen different unit cells, which have the shapes shown in Figure 10.56.\n"]], ["block_4", [{"image_0": "536_0.png", "coords": [247, 101, 364, 207]}]], ["block_5", [" 10.6 \u2022 Lattice Structures in Crystalline Solids \n 523 \n"]]], "page_537": [["block_0", [" 524 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [" The Structures of Ionic Crystals \n"]], ["block_2", ["Ionic crystals consist of two or more different kinds of ions that usually have different sizes. The packing of\nthese ions into a crystal structure is more complex than the packing of metal atoms that are the same size.\n"]], ["block_3", ["Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same\nin every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", [{"image_0": "537_0.png", "coords": [72, 57, 539, 633]}]], ["block_6", [" FIGURE 10.56 \nThere are seven different lattice systems and 14 different unit cells.\n"]]], "page_538": [["block_0", ["surrounded by as many ions as possible of the opposite charge and (2) when the cations and anions are in\ncontact with each other. Structures are determined by two principal factors: the relative sizes of the ions and\nthe ratio of the numbers of positive and negative ions in the compound.\n"]], ["block_1", ["In simple ionic structures, we usually find the anions, which are normally larger than the cations, arranged in a\nclosest-packed array. (As seen previously, additional electrons attracted to the same nucleus make anions\nlarger and fewer electrons attracted to the same nucleus make cations smaller when compared to the atoms\nfrom which they are formed.) The smaller cations commonly occupy one of two types of holes (or interstices)\nremaining between the anions. The smaller of the holes is found between three anions in one plane and one\nanion in an adjacent plane. The four anions surrounding this hole are arranged at the corners of a tetrahedron,\nso the hole is called a tetrahedral hole . The larger type of hole is found at the center of six anions (three in one\nlayer and three in an adjacent layer) located at the corners of an octahedron; this is called an octahedral hole .\nFigure 10.57 illustrates both of these types of holes.\n"]], ["block_2", ["Depending on the relative sizes of the cations and anions, the cations of an ionic compound may occupy\ntetrahedral or octahedral holes, as illustrated in Figure 10.58. Relatively small cations occupy tetrahedral\nholes, and larger cations occupy octahedral holes. If the cations are too large to fit into the octahedral holes, the\nanions may adopt a more open structure, such as a simple cubic array. The larger cations can then occupy the\nlarger cubic holes made possible by the more open spacing.\n"]], ["block_3", [{"image_0": "538_0.png", "coords": [72, 509, 540, 669]}]], ["block_4", ["There are two tetrahedral holes for each anion in either an HCP or CCP array of anions. A compound that\ncrystallizes in a closest-packed array of anions with cations in the tetrahedral holes can have a maximum\ncation:anion ratio of 2:1; all of the tetrahedral holes are filled at this ratio. Examples include Li2O, Na2O, Li2S,\n"]], ["block_5", [" FIGURE 10.57 \nCations may occupy two types of holes between anions: octahedral holes or tetrahedral holes.\n"]], ["block_6", [" FIGURE 10.58 \nA cation\u2019s size and the shape of the hole occupied by the compound are directly related.\n"]], ["block_7", [{"image_1": "538_1.png", "coords": [189, 221, 423, 418]}]], ["block_8", [" 10.6 \u2022 Lattice Structures in Crystalline Solids \n 525 \n"]]], "page_539": [["block_0", [" 526 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", ["and Na2S. Compounds with a ratio of less than 2:1 may also crystallize in a closest-packed array of anions with\ncations in the tetrahedral holes, if the ionic sizes fit. In these compounds, however, some of the tetrahedral\nholes remain vacant.\n"]], ["block_2", [" Occupancy of Tetrahedral Holes \n"]], ["block_3", ["Zinc sulfide is an important industrial source of zinc and is also used as a white pigment in paint. Zinc sulfide\ncrystallizes with zinc ions occupying one-half of the tetrahedral holes in a closest-packed array of sulfide ions.\nWhat is the formula of zinc sulfide?\n"]], ["block_4", [" Solution \n"]], ["block_5", ["Because there are two tetrahedral holes per anion (sulfide ion) and one-half of these holes are occupied by zinc\nions, there must be\nor 1, zinc ion per sulfide ion. Thus, the formula is ZnS.\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["Lithium selenide can be described as a closest-packed array of selenide ions with lithium ions in all of the\ntetrahedral holes. What it the formula of lithium selenide?\n"]], ["block_8", [" Answer: \nLi2Se\n"]], ["block_9", ["The ratio of octahedral holes to anions in either an HCP or CCP structure is 1:1. Thus, compounds with cations\nin octahedral holes in a closest-packed array of anions can have a maximum cation:anion ratio of 1:1. In NiO,\nMnS, NaCl, and KH, for example, all of the octahedral holes are filled. Ratios of less than 1:1 are observed when\nsome of the octahedral holes remain empty.\n"]], ["block_10", [" Stoichiometry of Ionic Compounds \n"]], ["block_11", ["Sapphire is aluminum oxide. Aluminum oxide crystallizes with aluminum ions in two-thirds of the octahedral\nholes in a closest-packed array of oxide ions. What is the formula of aluminum oxide?\n"]], ["block_12", [" Solution \n"]], ["block_13", ["Because there is one octahedral hole per anion (oxide ion) and only two-thirds of these holes are occupied, the\nratio of aluminum to oxygen must be\n:1, which would give\nThe simplest whole number ratio is 2:3, so\n"]], ["block_14", ["the formula is Al2O3.\n"]], ["block_15", [" Check Your Learning \n"]], ["block_16", ["The white pigment titanium oxide crystallizes with titanium ions in one-half of the octahedral holes in a\nclosest-packed array of oxide ions. What is the formula of titanium oxide?\n"]], ["block_17", [" Answer: \nTiO2\n"]], ["block_18", ["In a simple cubic array of anions, there is one cubic hole that can be occupied by a cation for each anion in the\narray. In CsCl, and in other compounds with the same structure, all of the cubic holes are occupied. Half of the\ncubic holes are occupied in SrH2, UO2, SrCl2, and CaF2.\n"]], ["block_19", ["Different types of ionic compounds often crystallize in the same structure when the relative sizes of their ions\nand their stoichiometries (the two principal features that determine structure) are similar.\n"]], ["block_20", [" Access for free at openstax.org \n"]], ["block_21", ["EXAMPLE 10.16\n"]], ["block_22", ["EXAMPLE 10.17\n"]]], "page_540": [["block_0", [" Unit Cells of Ionic Compounds \n"]], ["block_1", ["Many ionic compounds crystallize with cubic unit cells, and we will use these compounds to describe the\ngeneral features of ionic structures.\n"]], ["block_2", ["When an ionic compound is composed of cations and anions of similar size in a 1:1 ratio, it typically forms a\nsimple cubic structure. Cesium chloride, CsCl, (illustrated in Figure 10.59) is an example of this, with Csand\nClhaving radii of 174 pm and 181 pm, respectively. We can think of this as chloride ions forming a simple\ncubic unit cell, with a cesium ion in the center; or as cesium ions forming a unit cell with a chloride ion in the\ncenter; or as simple cubic unit cells formed by Csions overlapping unit cells formed by Clions. Cesium ions\nand chloride ions touch along the body diagonals of the unit cells. One cesium ion and one chloride ion are\npresent per unit cell, giving the l:l stoichiometry required by the formula for cesium chloride. Note that there is\nno lattice point in the center of the cell, and CsCl is not a BCC structure because a cesium ion is not identical to\na chloride ion.\n"]], ["block_3", [" FIGURE 10.59 \nIonic compounds with similar-sized cations and anions, such as CsCl, usually form a simple cubic\n"]], ["block_4", ["structure. They can be described by unit cells with either cations at the corners or anions at the corners.\n"]], ["block_5", ["We have said that the location of lattice points is arbitrary. This is illustrated by an alternate description of the\nCsCl structure in which the lattice points are located in the centers of the cesium ions. In this description, the\ncesium ions are located on the lattice points at the corners of the cell, and the chloride ion is located at the\ncenter of the cell. The two unit cells are different, but they describe identical structures.\n"]], ["block_6", ["When an ionic compound is composed of a 1:1 ratio of cations and anions that differ significantly in size, it\ntypically crystallizes with an FCC unit cell, like that shown in Figure 10.60. Sodium chloride, NaCl, is an\nexample of this, with Naand Clhaving radii of 102 pm and 181 pm, respectively. We can think of this as\nchloride ions forming an FCC cell, with sodium ions located in the octahedral holes in the middle of the cell\nedges and in the center of the cell. The sodium and chloride ions touch each other along the cell edges. The\nunit cell contains four sodium ions and four chloride ions, giving the 1:1 stoichiometry required by the\nformula, NaCl.\n"]], ["block_7", [{"image_0": "540_0.png", "coords": [130, 228, 481, 374]}]], ["block_8", [" 10.6 \u2022 Lattice Structures in Crystalline Solids \n 527 \n"]]], "page_541": [["block_0", [" 528 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [{"image_0": "541_0.png", "coords": [72, 57, 540, 218]}]], ["block_2", [" FIGURE 10.60 \nIonic compounds with anions that are much larger than cations, such as NaCl, usually form an FCC\n"]], ["block_3", ["structure. They can be described by FCC unit cells with cations in the octahedral holes.\n"]], ["block_4", ["The cubic form of zinc sulfide, zinc blende, also crystallizes in an FCC unit cell, as illustrated in Figure 10.61.\nThis structure contains sulfide ions on the lattice points of an FCC lattice. (The arrangement of sulfide ions is\nidentical to the arrangement of chloride ions in sodium chloride.) The radius of a zinc ion is only about 40% of\nthe radius of a sulfide ion, so these small Znions are located in alternating tetrahedral holes, that is, in one\nhalf of the tetrahedral holes. There are four zinc ions and four sulfide ions in the unit cell, giving the empirical\nformula ZnS.\n"]], ["block_5", [" FIGURE 10.61 \nZnS, zinc sulfide (or zinc blende) forms an FCC unit cell with sulfide ions at the lattice points and\n"]], ["block_6", ["much smaller zinc ions occupying half of the tetrahedral holes in the structure.\n"]], ["block_7", ["A calcium fluoride unit cell, like that shown in Figure 10.62, is also an FCC unit cell, but in this case, the cations\nare located on the lattice points; equivalent calcium ions are located on the lattice points of an FCC lattice. All\nof the tetrahedral sites in the FCC array of calcium ions are occupied by fluoride ions. There are four calcium\nions and eight fluoride ions in a unit cell, giving a calcium:fluorine ratio of 1:2, as required by the chemical\nformula, CaF2. Close examination of Figure 10.62 will reveal a simple cubic array of fluoride ions with calcium\nions in one half of the cubic holes. The structure cannot be described in terms of a space lattice of points on\nthe fluoride ions because the fluoride ions do not all have identical environments. The orientation of the four\ncalcium ions about the fluoride ions differs.\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", [{"image_1": "541_1.png", "coords": [189, 334, 423, 460]}]]], "page_542": [["block_0", [" FIGURE 10.62 \nCalcium fluoride, CaF2, forms an FCC unit cell with calcium ions (green) at the lattice points and\n"]], ["block_1", ["fluoride ions (red) occupying all of the tetrahedral sites between them.\n"]], ["block_2", [" Calculation of Ionic Radii \n"]], ["block_3", ["If we know the edge length of a unit cell of an ionic compound and the position of the ions in the cell, we can\ncalculate ionic radii for the ions in the compound if we make assumptions about individual ionic shapes and\ncontacts.\n"]], ["block_4", [" Calculation of Ionic Radii \n"]], ["block_5", ["The edge length of the unit cell of LiCl (NaCl-like structure, FCC) is 0.514 nm or 5.14 \u00c5. Assuming that the\nlithium ion is small enough so that the chloride ions are in contact, as in Figure 10.60, calculate the ionic\nradius for the chloride ion.\n"]], ["block_6", ["Note: The length unit angstrom, \u00c5, is often used to represent atomic-scale dimensions and is equivalent to\n10m.\n"]], ["block_7", [" Solution \n"]], ["block_8", ["On the face of a LiCl unit cell, chloride ions contact each other across the diagonal of the face:\n"]], ["block_9", [{"image_0": "542_0.png", "coords": [72, 439, 398, 560]}]], ["block_10", ["Drawing a right triangle on the face of the unit cell, we see that the length of the diagonal is equal to four\nchloride radii (one radius from each corner chloride and one diameter\u2014which equals two radii\u2014from the\nchloride ion in the center of the face), so d = 4r. From the Pythagorean theorem, we have:\n"]], ["block_11", ["which yields:\n"]], ["block_12", ["Solving this gives:\n"]], ["block_13", ["EXAMPLE 10.18\n"]], ["block_14", [{"image_1": "542_1.png", "coords": [189, 57, 423, 183]}]], ["block_15", [" 10.6 \u2022 Lattice Structures in Crystalline Solids \n 529 \n"]]], "page_543": [["block_0", [" 530 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", ["When a beam of monochromatic X-rays strikes a crystal, its rays are scattered in all directions by the atoms\nwithin the crystal. When scattered waves traveling in the same direction encounter one another, they undergo\ninterference, a process by which the waves combine to yield either an increase or a decrease in amplitude\n(intensity) depending upon the extent to which the combining waves\u2019 maxima are separated (see Figure\n10.63).\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["The edge length of the unit cell of KCl (NaCl-like structure, FCC) is 6.28 \u00c5. Assuming anion-cation contact along\nthe cell edge, calculate the radius of the potassium ion. The radius of the chloride ion is 1.82 \u00c5.\n"]], ["block_4", [" Answer: \nThe radius of the potassium ion is 1.33 \u00c5.\n"]], ["block_5", ["It is important to realize that values for ionic radii calculated from the edge lengths of unit cells depend on\nnumerous assumptions, such as a perfect spherical shape for ions, which are approximations at best. Hence,\nsuch calculated values are themselves approximate and comparisons cannot be pushed too far. Nevertheless,\nthis method has proved useful for calculating ionic radii from experimental measurements such as X-ray\ncrystallographic determinations.\n"]], ["block_6", [" X-Ray Crystallography \n"]], ["block_7", ["The size of the unit cell and the arrangement of atoms in a crystal may be determined from measurements of\nthe diffraction of X-rays by the crystal, termed X-ray crystallography . Diffraction is the change in the\ndirection of travel experienced by an electromagnetic wave when it encounters a physical barrier whose\ndimensions are comparable to those of the wavelength of the light. X-rays are electromagnetic radiation with\nwavelengths about as long as the distance between neighboring atoms in crystals (on the order of a few \u00c5).\n"]], ["block_8", [" FIGURE 10.63 \nLight waves occupying the same space experience interference, combining to yield waves of greater\n"]], ["block_9", ["(a) or lesser (b) intensity, depending upon the separation of their maxima and minima.\n"]], ["block_10", ["When X-rays of a certain wavelength, \u03bb, are scattered by atoms in adjacent crystal planes separated by a\ndistance, d, they may undergo constructive interference when the difference between the distances traveled by\nthe two waves prior to their combination is an integer factor, n, of the wavelength. This condition is satisfied\nwhen the angle of the diffracted beam, \u03b8, is related to the wavelength and interatomic distance by the equation:\n"]], ["block_11", ["This relation is known as the Bragg equation in honor of W. H. Bragg, the English physicist who first explained\nthis phenomenon. Figure 10.64 illustrates two examples of diffracted waves from the same two crystal planes.\nThe figure on the left depicts waves diffracted at the Bragg angle, resulting in constructive interference, while\nthat on the right shows diffraction and a different angle that does not satisfy the Bragg condition, resulting in\ndestructive interference.\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", [{"image_0": "543_0.png", "coords": [130, 380, 481, 479]}]]], "page_544": [["block_0", [" FIGURE 10.64 \nThe diffraction of X-rays scattered by the atoms within a crystal permits the determination of the\n"]], ["block_1", ["distance between the atoms. The top image depicts constructive interference between two scattered waves and a\nresultant diffracted wave of high intensity. The bottom image depicts destructive interference and a low intensity\ndiffracted wave.\n"]], ["block_2", ["Visit this site (http://openstax.org/l/16bragg) for more details on the Bragg equation and a simulator that allows\nyou to explore the effect of each variable on the intensity of the diffracted wave.\n"]], ["block_3", ["An X-ray diffractometer, such as the one illustrated in Figure 10.65, may be used to measure the angles at\nwhich X-rays are diffracted when interacting with a crystal as described earlier. From such measurements, the\nBragg equation may be used to compute distances between atoms as demonstrated in the following example\nexercise.\n"]], ["block_4", ["LINK TO LEARNING\n"]], ["block_5", [{"image_0": "544_0.png", "coords": [143, 57, 468, 421]}]], ["block_6", [" 10.6 \u2022 Lattice Structures in Crystalline Solids \n 531 \n"]]], "page_545": [["block_0", [" 532 \n 10 \u2022 Liquids and Solids \n"]], ["block_1", [" FIGURE 10.65 \n(a) In a diffractometer, a beam of X-rays strikes a crystalline material, producing (b) an X-ray\n"]], ["block_2", ["diffraction pattern that can be analyzed to determine the crystal structure.\n"]], ["block_3", [" Using the Bragg Equation \n"]], ["block_4", ["In a diffractometer, X-rays with a wavelength of 0.1315 nm were used to produce a diffraction pattern for\ncopper. The first order diffraction (n = 1) occurred at an angle \u03b8 = 25.25\u00b0. Determine the spacing between the\ndiffracting planes in copper.\n"]], ["block_5", [" Solution \n"]], ["block_6", ["The distance between the planes is found by solving the Bragg equation, n\u03bb = 2d sin \u03b8, for d.\n"]], ["block_7", ["This gives:\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["A crystal with spacing between planes equal to 0.394 nm diffracts X-rays with a wavelength of 0.147 nm. What\nis the angle for the first order diffraction?\n"]], ["block_10", [" Answer: \n10.8\u00b0\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["Portrait of a Chemist\n"]], ["block_13", [" X-ray Crystallographer Rosalind Franklin \nThe discovery of the structure of DNA in 1953 by Francis Crick and James Watson is one of the great\nachievements in the history of science. They were awarded the 1962 Nobel Prize in Physiology or Medicine,\nalong with Maurice Wilkins, who provided experimental proof of DNA\u2019s structure. British chemist Rosalind\nFranklin made invaluable contributions to this monumental achievement through her work in measuring\nX-ray diffraction images of DNA. Early in her career, Franklin\u2019s research on the structure of coals proved\nhelpful to the British war effort. After shifting her focus to biological systems in the early 1950s, Franklin\nand doctoral student Raymond Gosling discovered that DNA consists of two forms: a long, thin fiber formed\nwhen wet (type \u201cB\u201d) and a short, wide fiber formed when dried (type \u201cA\u201d). Her X-ray diffraction images of\nDNA (Figure 10.66) provided the crucial information that allowed Watson and Crick to confirm that DNA\nforms a double helix, and to determine details of its size and structure. Franklin also conducted pioneering\nresearch on viruses and the RNA that contains their genetic information, uncovering new information that\nradically changed the body of knowledge in the field. After developing ovarian cancer, Franklin continued\n"]], ["block_14", ["EXAMPLE 10.19\n"]], ["block_15", [{"image_0": "545_0.png", "coords": [130, 57, 481, 235]}]]], "page_546": [["block_0", ["to work until her death in 1958 at age 37. Among many posthumous recognitions of her work, the Chicago\nMedical School of Finch University of Health Sciences changed its name to the Rosalind Franklin\nUniversity of Medicine and Science in 2004, and adopted an image of her famous X-ray diffraction image of\nDNA as its official university logo.\n"]], ["block_1", [" FIGURE 10.66 \nThis illustration shows an X-ray diffraction image similar to the one Franklin found in her\n"]], ["block_2", ["research. (credit: National Institutes of Health)\n"]], ["block_3", [{"image_0": "546_0.png", "coords": [247, 114, 364, 251]}]], ["block_4", [" 10.6 \u2022 Lattice Structures in Crystalline Solids \n 533 \n"]]], "page_547": [["block_0", [" 534 \n 10 \u2022 Key Terms \n"]], ["block_1", [" Key Terms \n"]], ["block_2", [" adhesive force \nforce of attraction between\n"]], ["block_3", [" amorphous solid \n(also, noncrystalline solid) solid\n"]], ["block_4", [" body-centered cubic (BCC) solid \ncrystalline\n"]], ["block_5", [" body-centered cubic unit cell \nsimplest repeating\n"]], ["block_6", [" boiling point \ntemperature at which the vapor\n"]], ["block_7", [" Bragg equation \nequation that relates the angles at\n"]], ["block_8", [" capillary action \nflow of liquid within a porous\n"]], ["block_9", [" Clausius-Clapeyron equation \nmathematical\n"]], ["block_10", [" cohesive force \nforce of attraction between\n"]], ["block_11", [" condensation \nchange from a gaseous to a liquid\n"]], ["block_12", [" coordination number \nnumber of atoms closest to\n"]], ["block_13", [" covalent network solid \nsolid whose particles are\n"]], ["block_14", [" critical point \ntemperature and pressure above\n"]], ["block_15", [" crystalline solid \nsolid in which the particles are\n"]], ["block_16", [" cubic closest packing (CCP) \ncrystalline structure\n"]], ["block_17", [" deposition \nchange from a gaseous state directly to\n"]], ["block_18", [" diffraction \nredirection of electromagnetic\n"]], ["block_19", [" dipole-dipole attraction \nintermolecular attraction\n"]], ["block_20", [" dispersion force \n(also, London dispersion force )\n"]], ["block_21", [" Access for free at openstax.org \n"]], ["block_22", ["molecules of different chemical identities\n"]], ["block_23", ["in which the particles lack an ordered internal\nstructure\n"]], ["block_24", ["structure that has a cubic unit cell with lattice\npoints at the corners and in the center of the cell\n"]], ["block_25", ["unit of a body-centered cubic crystal; it is a cube\ncontaining lattice points at each corner and in the\ncenter of the cube\n"]], ["block_26", ["pressure of a liquid equals the pressure of the gas\nabove it\n"]], ["block_27", ["which X-rays are diffracted by the atoms within a\ncrystal\n"]], ["block_28", ["material due to the attraction of the liquid\nmolecules to the surface of the material and to\nother liquid molecules\n"]], ["block_29", ["relationship between the temperature, vapor\npressure, and enthalpy of vaporization for a\nsubstance\n"]], ["block_30", ["identical molecules\n"]], ["block_31", ["state\n"]], ["block_32", ["any given atom in a crystal or to the central metal\natom in a complex\n"]], ["block_33", ["held together by covalent bonds\n"]], ["block_34", ["which a gas cannot be condensed into a liquid\n"]], ["block_35", ["arranged in a definite repeating pattern\n"]], ["block_36", ["in which planes of closely packed atoms or ions\nare stacked as a series of three alternating layers\nof different relative orientations (ABC)\n"]], ["block_37", ["a solid state\n"]], ["block_38", ["radiation that occurs when it encounters a\nphysical barrier of appropriate dimensions\n"]], ["block_39", ["between two permanent dipoles\n"]], ["block_40", ["attraction between two rapidly fluctuating,\n"]], ["block_41", [" dynamic equilibrium \nstate of a system in which\n"]], ["block_42", [" face-centered cubic (FCC) solid \ncrystalline\n"]], ["block_43", [" face-centered cubic unit cell \nsimplest repeating\n"]], ["block_44", [" freezing \nchange from a liquid state to a solid state\n"]], ["block_45", [" freezing point \ntemperature at which the solid and\n"]], ["block_46", [" hexagonal closest packing (HCP) \ncrystalline\n"]], ["block_47", [" hole \n(also, interstice) space between atoms within\n"]], ["block_48", [" hydrogen bonding \noccurs when exceptionally\n"]], ["block_49", [" induced dipole \ntemporary dipole formed when the\n"]], ["block_50", [" instantaneous dipole \ntemporary dipole that\n"]], ["block_51", [" intermolecular force \nnoncovalent attractive force\n"]], ["block_52", [" interstitial sites \nspaces between the regular\n"]], ["block_53", [" ionic solid \nsolid composed of positive and negative\n"]], ["block_54", [" isomorphous \npossessing the same crystalline\n"]], ["block_55", [" melting \nchange from a solid state to a liquid state\n"]], ["block_56", [" melting point \ntemperature at which the solid and\n"]], ["block_57", [" metallic solid \nsolid composed of metal atoms\n"]], ["block_58", [" molecular solid \nsolid composed of neutral\n"]], ["block_59", [" normal boiling point \ntemperature at which a\n"]], ["block_60", ["temporary dipoles; significant only when\nparticles are very close together\n"]], ["block_61", ["reciprocal processes are occurring at equal rates\n"]], ["block_62", ["structure consisting of a cubic unit cell with\nlattice points on the corners and in the center of\neach face\n"]], ["block_63", ["unit of a face-centered cubic crystal; it is a cube\ncontaining lattice points at each corner and in the\ncenter of each face\n"]], ["block_64", ["liquid phases of a substance are in equilibrium;\nsee also melting point\n"]], ["block_65", ["structure in which close packed layers of atoms\nor ions are stacked as a series of two alternating\nlayers of different relative orientations (AB)\n"]], ["block_66", ["a crystal\n"]], ["block_67", ["strong dipoles attract; bonding that exists when\nhydrogen is bonded to one of the three most\nelectronegative elements: F, O, or N\n"]], ["block_68", ["electrons of an atom or molecule are distorted by\nthe instantaneous dipole of a neighboring atom or\nmolecule\n"]], ["block_69", ["occurs for a brief moment in time when the\nelectrons of an atom or molecule are distributed\nasymmetrically\n"]], ["block_70", ["between atoms, molecules, and/or ions\n"]], ["block_71", ["particle positions in any array of atoms or ions\n"]], ["block_72", ["ions held together by strong electrostatic\nattractions\n"]], ["block_73", ["structure\n"]], ["block_74", ["liquid phases of a substance are in equilibrium;\nsee also freezing point\n"]], ["block_75", ["molecules held together by intermolecular forces\nof attraction\n"]]], "page_548": [["block_0", [" octahedral hole \nopen space in a crystal at the\n"]], ["block_1", [" phase diagram \npressure-temperature graph\n"]], ["block_2", [" polarizability \nmeasure of the ability of a charge to\n"]], ["block_3", [" simple cubic structure \ncrystalline structure with a\n"]], ["block_4", [" simple cubic unit cell \n(also, primitive cubic unit\n"]], ["block_5", [" space lattice \nall points within a crystal that have\n"]], ["block_6", [" sublimation \nchange from solid state directly to\n"]], ["block_7", [" supercritical fluid \nsubstance at a temperature and\n"]], ["block_8", [" surface tension \nenergy required to increase the\n"]], ["block_9", [" Key Equations \n"]], ["block_10", [" Summary \n"]], ["block_11", [" 10.1 Intermolecular Forces \n"]], ["block_12", ["The physical properties of condensed matter\n(liquids and solids) can be explained in terms of the\nkinetic molecular theory. In a liquid, intermolecular\nattractive forces hold the molecules in contact,\nalthough they still have sufficient KE to move past\neach other.\n"]], ["block_13", ["Intermolecular attractive forces, collectively referred\nto as van der Waals forces, are responsible for the\nbehavior of liquids and solids and are electrostatic in\nnature. Dipole-dipole attractions result from the\nelectrostatic attraction of the partial negative end of\none polar molecule for the partial positive end of\nanother. The temporary dipole that results from the\n"]], ["block_14", ["liquid\u2019s vapor pressure equals 1 atm (760 torr)\n"]], ["block_15", ["center of six particles located at the corners of an\noctahedron\n"]], ["block_16", ["summarizing conditions under which the phases\nof a substance can exist\n"]], ["block_17", ["distort a molecule\u2019s charge distribution (electron\ncloud)\n"]], ["block_18", ["cubic unit cell with lattice points only at the\ncorners\n"]], ["block_19", ["cell) unit cell in the simple cubic structure\n"]], ["block_20", ["identical environments\n"]], ["block_21", ["gaseous state\n"]], ["block_22", ["pressure higher than its critical point; exhibits\nproperties intermediate between those of gaseous\nand liquid states\n"]], ["block_23", ["area, or length, of a liquid surface by a given\namount\n"]], ["block_24", [" tetrahedral hole \ntetrahedral space formed by four\n"]], ["block_25", [" triple point \ntemperature and pressure at which the\n"]], ["block_26", [" unit cell \nsmallest portion of a space lattice that is\n"]], ["block_27", [" vacancy \ndefect that occurs when a position that\n"]], ["block_28", [" van der Waals force \nattractive or repulsive force\n"]], ["block_29", [" vapor pressure \n(also, equilibrium vapor pressure )\n"]], ["block_30", [" vaporization \nchange from liquid state to gaseous\n"]], ["block_31", [" viscosity \nmeasure of a liquid\u2019s resistance to flow\n"]], ["block_32", [" X-ray crystallography \nexperimental technique for\n"]], ["block_33", ["motion of the electrons in an atom can induce a\ndipole in an adjacent atom and give rise to the\nLondon dispersion force. London forces increase\nwith increasing molecular size. Hydrogen bonds are\na special type of dipole-dipole attraction that results\nwhen hydrogen is bonded to one of the three most\nelectronegative elements: F, O, or N.\n"]], ["block_34", [" 10.2 Properties of Liquids \n"]], ["block_35", ["The intermolecular forces between molecules in the\nliquid state vary depending upon their chemical\nidentities and result in corresponding variations in\nvarious physical properties. Cohesive forces\nbetween like molecules are responsible for a liquid\u2019s\nviscosity (resistance to flow) and surface tension\n"]], ["block_36", ["atoms or ions in a crystal\n"]], ["block_37", ["vapor, liquid, and solid phases of a substance are\nin equilibrium\n"]], ["block_38", ["repeated in three dimensions to form the entire\nlattice\n"]], ["block_39", ["should contain an atom or ion is vacant\n"]], ["block_40", ["between molecules, including dipole-dipole,\ndipole-induced dipole, and London dispersion\nforces; does not include forces due to covalent or\nionic bonding, or the attraction between ions and\nmolecules\n"]], ["block_41", ["pressure exerted by a vapor in equilibrium with a\nsolid or a liquid at a given temperature\n"]], ["block_42", ["state\n"]], ["block_43", ["determining distances between atoms in a crystal\nby measuring the angles at which X-rays are\ndiffracted when passing through the crystal\n"]], ["block_44", [" 10 \u2022 Key Equations \n 535 \n"]]], "page_549": [["block_0", [" 536 \n 10 \u2022 Exercises \n"]], ["block_1", ["(elasticity of a liquid surface). Adhesive forces\nbetween the molecules of a liquid and different\nmolecules composing a surface in contact with the\nliquid are responsible for phenomena such as\nsurface wetting and capillary rise.\n"]], ["block_2", [" 10.3 Phase Transitions \n"]], ["block_3", ["Phase transitions are processes that convert matter\nfrom one physical state into another. There are six\nphase transitions between the three phases of\nmatter. Melting, vaporization, and sublimation are\nall endothermic processes, requiring an input of\nheat to overcome intermolecular attractions. The\nreciprocal transitions of freezing, condensation, and\ndeposition are all exothermic processes, involving\nheat as intermolecular attractive forces are\nestablished or strengthened. The temperatures at\nwhich phase transitions occur are determined by the\nrelative strengths of intermolecular attractions and\nare, therefore, dependent on the chemical identity of\nthe substance.\n"]], ["block_4", [" 10.4 Phase Diagrams \n"]], ["block_5", ["The temperature and pressure conditions at which a\nsubstance exists in solid, liquid, and gaseous states\nare summarized in a phase diagram for that\nsubstance. Phase diagrams are combined plots of\nthree pressure-temperature equilibrium curves:\nsolid-liquid, liquid-gas, and solid-gas. These curves\nrepresent the relationships between phase-\ntransition temperatures and pressures. The point of\nintersection of all three curves represents the\nsubstance\u2019s triple point\u2014the temperature and\npressure at which all three phases are in\nequilibrium. At pressures below the triple point, a\nsubstance cannot exist in the liquid state, regardless\nof its temperature. The terminus of the liquid-gas\ncurve represents the substance\u2019s critical point, the\npressure and temperature above which a liquid\nphase cannot exist.\n"]], ["block_6", [" 10.5 The Solid State of Matter \n"]], ["block_7", ["Some substances form crystalline solids consisting\n"]], ["block_8", [" Exercises \n"]], ["block_9", [" 10.1 Intermolecular Forces \n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [" 1 . In terms of their bulk properties, how do liquids and solids differ? How are they similar?\n 2 . In terms of the kinetic molecular theory, in what ways are liquids similar to solids? In what ways are\n"]], ["block_12", [" 3 . In terms of the kinetic molecular theory, in what ways are liquids similar to gases? In what ways are liquids\n"]], ["block_13", ["liquids different from solids?\n"]], ["block_14", ["different from gases?\n"]], ["block_15", ["of particles in a very organized structure; others\nform amorphous (noncrystalline) solids with an\ninternal structure that is not ordered. The main\ntypes of crystalline solids are ionic solids, metallic\nsolids, covalent network solids, and molecular\nsolids. The properties of the different kinds of\ncrystalline solids are due to the types of particles of\nwhich they consist, the arrangements of the\nparticles, and the strengths of the attractions\nbetween them. Because their particles experience\nidentical attractions, crystalline solids have distinct\nmelting temperatures; the particles in amorphous\nsolids experience a range of interactions, so they\nsoften gradually and melt over a range of\ntemperatures. Some crystalline solids have defects\nin the definite repeating pattern of their particles.\nThese defects (which include vacancies, atoms or\nions not in the regular positions, and impurities)\nchange physical properties such as electrical\nconductivity, which is exploited in the silicon\ncrystals used to manufacture computer chips.\n"]], ["block_16", [" 10.6 Lattice Structures in Crystalline Solids \n"]], ["block_17", ["The structures of crystalline metals and simple ionic\ncompounds can be described in terms of packing of\nspheres. Metal atoms can pack in hexagonal closest-\npacked structures, cubic closest-packed structures,\nbody-centered structures, and simple cubic\nstructures. The anions in simple ionic structures\ncommonly adopt one of these structures, and the\ncations occupy the spaces remaining between the\nanions. Small cations usually occupy tetrahedral\nholes in a closest-packed array of anions. Larger\ncations usually occupy octahedral holes. Still larger\ncations can occupy cubic holes in a simple cubic\narray of anions. The structure of a solid can be\ndescribed by indicating the size and shape of a unit\ncell and the contents of the cell. The type of\nstructure and dimensions of the unit cell can be\ndetermined by X-ray diffraction measurements.\n"]]], "page_550": [["block_0", [" 9 . Why do the boiling points of the noble gases increase in the order He < Ne < Ar < Kr < Xe?\n 10 . Neon and HF have approximately the same molecular masses.\n"]], ["block_1", [" 11 . Arrange each of the following sets of compounds in order of increasing boiling point temperature:\n"]], ["block_2", [" 12 . The molecular mass of butanol, C4H9OH, is 74.14; that of ethylene glycol, CH2(OH)CH2OH, is 62.08, yet\n"]], ["block_3", [" 13 . On the basis of intermolecular attractions, explain the differences in the boiling points of n\u2013butane (\u22121 \u00b0C)\n"]], ["block_4", [" 14 . On the basis of dipole moments and/or hydrogen bonding, explain in a qualitative way the differences in\n"]], ["block_5", [" 15 . The melting point of H2O(s) is 0 \u00b0C. Would you expect the melting point of H2S(s) to be \u221285 \u00b0C, 0 \u00b0C, or 185\n"]], ["block_6", [" 16 . Silane (SiH4), phosphine (PH3), and hydrogen sulfide (H2S) melt at \u2212185 \u00b0C, \u2212133 \u00b0C, and \u221285 \u00b0C,\n"]], ["block_7", [" 17 . Explain why a hydrogen bond between two water molecules is weaker than a hydrogen bond between two\n"]], ["block_8", [" 4 . Explain why liquids assume the shape of any container into which they are poured, whereas solids are\n"]], ["block_9", [" 5 . What is the evidence that all neutral atoms and molecules exert attractive forces on each other?\n 6 . Open the PhET States of Matter Simulation (http://openstax.org/l/16phetvisual) to answer the following\n"]], ["block_10", [" 7 . Define the following and give an example of each:\n"]], ["block_11", [" 8 . The types of intermolecular forces in a substance are identical whether it is a solid, a liquid, or a gas. Why\n"]], ["block_12", ["rigid and retain their shape.\n"]], ["block_13", ["questions:\n(a) Select the Solid, Liquid, Gas tab. Explore by selecting different substances, heating and cooling the\nsystems, and changing the state. What similarities do you notice between the four substances for each\nphase (solid, liquid, gas)? What differences do you notice?\n(b) For each substance, select each of the states and record the given temperatures. How do the given\ntemperatures for each state correlate with the strengths of their intermolecular attractions? Explain.\n(c) Select the Interaction Potential tab, and use the default neon atoms. Move the Ne atom on the right and\nobserve how the potential energy changes. Select the Total Force button, and move the Ne atom as before.\nWhen is the total force on each atom attractive and large enough to matter? Then select the Component\nForces button, and move the Ne atom. When do the attractive (van der Waals) and repulsive (electron\noverlap) forces balance? How does this relate to the potential energy versus the distance between atoms\ngraph? Explain.\n"]], ["block_14", ["(a) dispersion force\n(b) dipole-dipole attraction\n(c) hydrogen bond\n"]], ["block_15", ["then does a substance change phase from a gas to a liquid or to a solid?\n"]], ["block_16", ["(a) Explain why the boiling points of Neon and HF differ.\n(b) Compare the change in the boiling points of Ne, Ar, Kr, and Xe with the change of the boiling points of\nHF, HCl, HBr, and HI, and explain the difference between the changes with increasing atomic or molecular\nmass.\n"]], ["block_17", ["(a) HCl, H2O, SiH4\n(b) F2, Cl2, Br2\n(c) CH4, C2H6, C3H8\n(d) O2, NO, N2\n"]], ["block_18", ["their boiling points are 117.2 \u00b0C and 174 \u00b0C, respectively. Explain the reason for the difference.\n"]], ["block_19", ["and chloroethane (12 \u00b0C), which have similar molar masses.\n"]], ["block_20", ["the boiling points of acetone (56.2 \u00b0C) and 1-propanol (97.4 \u00b0C), which have similar molar masses.\n"]], ["block_21", ["\u00b0C? Explain your answer.\n"]], ["block_22", ["respectively. What does this suggest about the polar character and intermolecular attractions of the three\ncompounds?\n"]], ["block_23", ["hydrogen fluoride molecules.\n"]], ["block_24", [" 10 \u2022 Exercises \n 537 \n"]]], "page_551": [["block_0", [" 538 \n 10 \u2022 Exercises \n"]], ["block_1", [" 18 . Under certain conditions, molecules of acetic acid, CH3COOH, form \u201cdimers,\u201d pairs of acetic acid\n"]], ["block_2", [" 19 . Proteins are chains of amino acids that can form in a variety of arrangements, one of which is a helix.\n"]], ["block_3", [" 20 . The density of liquid NH3 is 0.64 g/mL; the density of gaseous NH3 at STP is 0.0007 g/mL. Explain the\n"]], ["block_4", [" 21 . Identify the intermolecular forces present in the following solids:\n"]], ["block_5", [" 10.2 Properties of Liquids \n"]], ["block_6", [" 22 . The test tubes shown here contain equal amounts of the specified motor oils. Identical metal spheres were\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", ["molecules held together by strong intermolecular attractions:\n"]], ["block_9", [{"image_0": "551_0.png", "coords": [91, 82, 170, 133]}]], ["block_10", ["Draw a dimer of acetic acid, showing how two CH3COOH molecules are held together, and stating the type\nof IMF that is responsible.\n"]], ["block_11", ["What kind of IMF is responsible for holding the protein strand in this shape? On the protein image, show\nthe locations of the IMFs that hold the protein together:\n"]], ["block_12", [{"image_1": "551_1.png", "coords": [91, 199, 206, 248]}]], ["block_13", ["difference between the densities of these two phases.\n"]], ["block_14", ["(a) CH3CH2OH\n(b) CH3CH2CH3\n(c) CH3CH2Cl\n"]], ["block_15", ["dropped at the same time into each of the tubes, and a brief moment later, the spheres had fallen to the\nheights indicated in the illustration.\nRank the motor oils in order of increasing viscosity, and explain your reasoning:\n"]], ["block_16", [{"image_2": "551_2.png", "coords": [91, 410, 442, 594]}]]], "page_552": [["block_0", [" 23 . Although steel is denser than water, a steel needle or paper clip placed carefully lengthwise on the surface\n"]], ["block_1", [" 24 . The surface tension and viscosity values for diethyl ether, acetone, ethanol, and ethylene glycol are shown\n"]], ["block_2", [" 25 . You may have heard someone use the figure of speech \u201cslower than molasses in winter\u201d to describe a\n"]], ["block_3", [" 26 . It is often recommended that you let your car engine run idle to warm up before driving, especially on cold\n"]], ["block_4", ["of still water can be made to float. Explain at a molecular level how this is possible.\n"]], ["block_5", ["here.\n"]], ["block_6", [{"image_0": "552_0.png", "coords": [91, 303, 559, 501]}]], ["block_7", ["(a) Explain their differences in viscosity in terms of the size and shape of their molecules and their IMFs.\n(b) Explain their differences in surface tension in terms of the size and shape of their molecules and their\nIMFs:\n"]], ["block_8", ["process that occurs slowly. Explain why this is an apt idiom, using concepts of molecular size and shape,\nmolecular interactions, and the effect of changing temperature.\n"]], ["block_9", ["winter days. While the benefit of prolonged idling is dubious, it is certainly true that a warm engine is\nmore fuel efficient than a cold one. Explain the reason for this.\n"]], ["block_10", [{"image_1": "552_1.png", "coords": [198, 82, 432, 255]}]], ["block_11", [" FIGURE 10.67 \n(credit: Cory Zanker)\n"]], ["block_12", [" 10 \u2022 Exercises \n 539 \n"]]], "page_553": [["block_0", [" 540 \n 10 \u2022 Exercises \n"]], ["block_1", [" 27 . The surface tension and viscosity of water at several different temperatures are given in this table.\n"]], ["block_2", [" 28 . At 25 \u00b0C, how high will water rise in a glass capillary tube with an inner diameter of 0.63 mm? Refer to\n"]], ["block_3", [" 29 . Water rises in a glass capillary tube to a height of 17 cm. What is the diameter of the capillary tube?\n"]], ["block_4", [" 10.3 Phase Transitions \n"]], ["block_5", [" 30 . Heat is added to boiling water. Explain why the temperature of the boiling water does not change. What\n"]], ["block_6", [" 31 . Heat is added to ice at 0 \u00b0C. Explain why the temperature of the ice does not change. What does change?\n 32 . What feature characterizes the dynamic equilibrium between a liquid and its vapor in a closed container?\n 33 . Identify two common observations indicating some liquids have sufficient vapor pressures to noticeably\n"]], ["block_7", [" 34 . Identify two common observations indicating some solids, such as dry ice and mothballs, have vapor\n"]], ["block_8", [" 35 . What is the relationship between the intermolecular forces in a liquid and its vapor pressure?\n 36 . What is the relationship between the intermolecular forces in a solid and its melting temperature?\n 37 . Why does spilled gasoline evaporate more rapidly on a hot day than on a cold day?\n 38 . Carbon tetrachloride, CCl4, was once used as a dry cleaning solvent, but is no longer used because it is\n"]], ["block_9", [" 39 . When is the boiling point of a liquid equal to its normal boiling point?\n 40 . How does the boiling of a liquid differ from its evaporation?\n 41 . Use the information in Figure 10.24 to estimate the boiling point of water in Denver when the atmospheric\n"]], ["block_10", [" 42 . A syringe at a temperature of 20 \u00b0C is filled with liquid ether in such a way that there is no space for any\n"]], ["block_11", [" 43 . Explain the following observations:\n"]], ["block_12", [" 44 . The enthalpy of vaporization of water is larger than its enthalpy of fusion. Explain why.\n 45 . Explain why the molar enthalpies of vaporization of the following substances increase in the order CH4 <\n"]], ["block_13", [" 46 . Explain why the enthalpies of vaporization of the following substances increase in the order CH4 < NH3 <\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["(a) As temperature increases, what happens to the surface tension of water? Explain why this occurs, in terms\nof molecular interactions and the effect of changing temperature.\n(b) As temperature increases, what happens to the viscosity of water? Explain why this occurs, in terms of\nmolecular interactions and the effect of changing temperature.\n"]], ["block_16", ["Example 10.4 for the required information.\n"]], ["block_17", ["does change?\n"]], ["block_18", ["evaporate?\n"]], ["block_19", ["pressures sufficient to sublime?\n"]], ["block_20", ["carcinogenic. At 57.8 \u00b0C, the vapor pressure of CCl4 is 54.0 kPa, and its enthalpy of vaporization is 33.05\nkJ/mol. Use this information to estimate the normal boiling point for CCl4.\n"]], ["block_21", ["pressure is 83.3 kPa.\n"]], ["block_22", ["vapor. If the temperature is kept constant and the plunger is withdrawn to create a volume that can be\noccupied by vapor, what would be the approximate pressure of the vapor produced?\n"]], ["block_23", ["(a) It takes longer to cook an egg in Ft. Davis, Texas (altitude, 5000 feet above sea level) than it does in\nBoston (at sea level).\n(b) Perspiring is a mechanism for cooling the body.\n"]], ["block_24", ["C2H6 < C3H8, even though the type of IMF (dispersion) is the same.\n"]], ["block_25", ["H2O, even though all three substances have approximately the same molar mass.\n"]], ["block_26", ["100 \u00b0C\n58.9\n0.28\n"]], ["block_27", [" Water \n Surface Tension (mN/m) \n Viscosity (mPa s) \n"]], ["block_28", ["20 \u00b0C\n72.8\n1.00\n"]], ["block_29", ["60 \u00b0C\n66.2\n0.47\n"]], ["block_30", ["0 \u00b0C\n75.6\n1.79\n"]]], "page_554": [["block_0", [" 47 . The enthalpy of vaporization of CO2(l) is 9.8 kJ/mol. Would you expect the enthalpy of vaporization of\n"]], ["block_1", [" 48 . The hydrogen fluoride molecule, HF, is more polar than a water molecule, H2O (for example, has a greater\n"]], ["block_2", [" 49 . Ethyl chloride (boiling point, 13 \u00b0C) is used as a local anesthetic. When the liquid is sprayed on the skin, it\n"]], ["block_3", [" 50 . Which contains the compounds listed correctly in order of increasing boiling points?\n"]], ["block_4", [" 51 . How much heat is required to convert 422 g of liquid H2O at 23.5 \u00b0C into steam at 150 \u00b0C?\n 52 . Evaporation of sweat requires energy and thus take excess heat away from the body. Some of the water\n"]], ["block_5", [" 53 . Titanium tetrachloride, TiCl4, has a melting point of \u221223.2 \u00b0C and has a \u0394H fusion = 9.37 kJ/mol.\n"]], ["block_6", [" 10.4 Phase Diagrams \n"]], ["block_7", [" 54 . From the phase diagram for water (Figure 10.31), determine the state of water at:\n"]], ["block_8", [" 55 . What phase changes will take place when water is subjected to varying pressure at a constant temperature\n"]], ["block_9", [" 56 . Pressure cookers allow food to cook faster because the higher pressure inside the pressure cooker\n"]], ["block_10", [" 57 . From the phase diagram for carbon dioxide in Figure 10.34, determine the state of CO2 at:\n"]], ["block_11", [" 58 . Determine the phase changes that carbon dioxide undergoes as pressure is increased at a constant\n"]], ["block_12", [" 59 . Consider a cylinder containing a mixture of liquid carbon dioxide in equilibrium with gaseous carbon\n"]], ["block_13", ["CS2(l) to be 28 kJ/mol, 9.8 kJ/mol, or \u22128.4 kJ/mol? Discuss the plausibility of each of these answers.\n"]], ["block_14", ["dipole moment), yet the molar enthalpy of vaporization for liquid hydrogen fluoride is lesser than that for\nwater. Explain.\n"]], ["block_15", ["cools the skin enough to freeze and numb it. Explain the cooling effect of liquid ethyl chloride.\n"]], ["block_16", ["(a) N2 < CS2 < H2O < KCl\n(b) H2O < N2 < CS2 < KCl\n(c) N2 < KCl < CS2 < H2O\n(d) CS2 < N2 < KCl < H2O\n(e) KCl < H2O < CS2 < N2\n"]], ["block_17", ["that you drink may eventually be converted into sweat and evaporate. If you drink a 20-ounce bottle of\nwater that had been in the refrigerator at 3.8 \u00b0C, how much heat is needed to convert all of that water into\nsweat and then to vapor? (Note: Your body temperature is 36.6 \u00b0C. For the purpose of solving this problem,\nassume that the thermal properties of sweat are the same as for water.)\n"]], ["block_18", ["(a) How much energy is required to melt 263.1 g TiCl4?\n(b) For TiCl4, which will likely have the larger magnitude: \u0394H fusion or \u0394H vaporization? Explain your\nreasoning.\n"]], ["block_19", ["(a) 35 \u00b0C and 85 kPa\n(b) \u221215 \u00b0C and 40 kPa\n(c) \u221215 \u00b0C and 0.1 kPa\n(d) 75 \u00b0C and 3 kPa\n(e) 40 \u00b0C and 0.1 kPa\n(f) 60 \u00b0C and 50 kPa\n"]], ["block_20", ["of 0.005 \u00b0C? At 40 \u00b0C? At \u221240 \u00b0C?\n"]], ["block_21", ["increases the boiling temperature of water. A particular pressure cooker has a safety valve that is set to\nvent steam if the pressure exceeds 3.4 atm. What is the approximate maximum temperature that can be\nreached inside this pressure cooker? Explain your reasoning.\n"]], ["block_22", ["(a) 20 \u00b0C and 1000 kPa\n(b) 10 \u00b0C and 2000 kPa\n(c) 10 \u00b0C and 100 kPa\n(d) \u221240 \u00b0C and 500 kPa\n(e) \u221280 \u00b0C and 1500 kPa\n(f) \u221280 \u00b0C and 10 kPa\n"]], ["block_23", ["temperature of (a) \u221250 \u00b0C and (b) 50 \u00b0C. If the temperature is held at \u221240 \u00b0C? At 20 \u00b0C? (See the phase\ndiagram in Figure 10.34.)\n"]], ["block_24", ["dioxide at an initial pressure of 65 atm and a temperature of 20 \u00b0C. Sketch a plot depicting the change in\nthe cylinder pressure with time as gaseous carbon dioxide is released at constant temperature.\n"]], ["block_25", [" 10 \u2022 Exercises \n 541 \n"]]], "page_555": [["block_0", [" 542 \n 10 \u2022 Exercises \n"]], ["block_1", [" 60 . Dry ice, CO2(s), does not melt at atmospheric pressure. It sublimes at a temperature of \u221278 \u00b0C. What is the\n"]], ["block_2", [" 61 . If a severe storm results in the loss of electricity, it may be necessary to use a clothesline to dry laundry. In\n"]], ["block_3", [" 62 . Is it possible to liquefy nitrogen at room temperature (about 25 \u00b0C)? Is it possible to liquefy sulfur dioxide\n"]], ["block_4", [" 63 . Elemental carbon has one gas phase, one liquid phase, and two different solid phases, as shown in the\n"]], ["block_5", [" 10.5 The Solid State of Matter \n"]], ["block_6", [" 64 . What types of liquids typically form amorphous solids?\n 65 . At very low temperatures oxygen, O2, freezes and forms a crystalline solid. Which best describes these\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", ["lowest pressure at which CO2(s) will melt to give CO2(l)? At approximately what temperature will this\noccur? (See Figure 10.34 for the phase diagram.)\n"]], ["block_9", ["many parts of the country in the dead of winter, the clothes will quickly freeze when they are hung on the\nline. If it does not snow, will they dry anyway? Explain your answer.\n"]], ["block_10", ["at room temperature? Explain your answers.\n"]], ["block_11", ["phase diagram:\n"]], ["block_12", [{"image_0": "555_0.png", "coords": [91, 183, 325, 447]}]], ["block_13", ["(a) On the phase diagram, label the gas and liquid regions.\n(b) Graphite is the most stable phase of carbon at normal conditions. On the phase diagram, label the\ngraphite phase.\n(c) If graphite at normal conditions is heated to 2500 K while the pressure is increased to 10Pa, it is\nconverted into diamond. Label the diamond phase.\n(d) Circle each triple point on the phase diagram.\n(e) In what phase does carbon exist at 5000 K and 10Pa?\n(f) If the temperature of a sample of carbon increases from 3000 K to 5000 K at a constant pressure of 10\n"]], ["block_14", ["Pa, which phase transition occurs, if any?\n"]], ["block_15", ["crystals?\n(a) ionic\n(b) covalent network\n(c) metallic\n(d) amorphous\n(e) molecular crystals\n"]]], "page_556": [["block_0", [" 66 . As it cools, olive oil slowly solidifies and forms a solid over a range of temperatures. Which best describes\n"]], ["block_1", [" 67 . Explain why ice, which is a crystalline solid, has a melting temperature of 0 \u00b0C, whereas butter, which is an\n"]], ["block_2", [" 68 . Identify the type of crystalline solid (metallic, network covalent, ionic, or molecular) formed by each of the\n"]], ["block_3", [" 69 . Identify the type of crystalline solid (metallic, network covalent, ionic, or molecular) formed by each of the\n"]], ["block_4", [" 70 . Classify each substance in the table as either a metallic, ionic, molecular, or covalent network solid:\n"]], ["block_5", ["the solid?\n(a) ionic\n(b) covalent network\n(c) metallic\n(d) amorphous\n(e) molecular crystals\n"]], ["block_6", ["amorphous solid, softens over a range of temperatures.\n"]], ["block_7", ["following substances:\n(a) SiO2\n(b) KCl\n(c) Cu\n(d) CO2\n(e) C (diamond)\n(f) BaSO4\n(g) NH3\n(h) NH4F\n(i) C2H5OH\n"]], ["block_8", ["following substances:\n(a) CaCl2\n(b) SiC\n(c) N2\n(d) Fe\n(e) C (graphite)\n(f) CH3CH2CH2CH3\n(g) HCl\n(h) NH4NO3\n(i) K3PO4\n"]], ["block_9", [" Substance \n Appearance \n Melting Point \n Electrical \n Conductivity \n Solubility in Water \n"]], ["block_10", ["X\nlustrous, malleable\n1500 \u00b0C\nhigh\ninsoluble\n"]], ["block_11", ["Z\nhard, white\n800 \u00b0C\nonly if melted/\n"]], ["block_12", ["Y\nsoft, yellow\n113 \u00b0C\nnone\ninsoluble\n"]], ["block_13", ["dissolved\nsoluble\n"]], ["block_14", [" 10 \u2022 Exercises \n 543 \n"]]], "page_557": [["block_0", [" 544 \n 10 \u2022 Exercises \n"]], ["block_1", [" 71 . Classify each substance in the table as either a metallic, ionic, molecular, or covalent network solid:\n"]], ["block_2", [" 72 . Identify the following substances as ionic, metallic, covalent network, or molecular solids:\n"]], ["block_3", [" 73 . Substance A is shiny, conducts electricity well, and melts at 975 \u00b0C. Substance A is likely a(n):\n"]], ["block_4", [" 74 . Substance B is hard, does not conduct electricity, and melts at 1200 \u00b0C. Substance B is likely a(n):\n"]], ["block_5", [" 10.6 Lattice Structures in Crystalline Solids \n"]], ["block_6", [" 75 . Describe the crystal structure of iron, which crystallizes with two equivalent metal atoms in a cubic unit\n"]], ["block_7", [" 76 . Describe the crystal structure of Pt, which crystallizes with four equivalent metal atoms in a cubic unit\n"]], ["block_8", [" 77 . What is the coordination number of a chromium atom in the body-centered cubic structure of chromium?\n 78 . What is the coordination number of an aluminum atom in the face-centered cubic structure of aluminum?\n 79 . Cobalt metal crystallizes in a hexagonal closest packed structure. What is the coordination number of a\n"]], ["block_9", [" 80 . Nickel metal crystallizes in a cubic closest packed structure. What is the coordination number of a nickel\n"]], ["block_10", [" 81 . Tungsten crystallizes in a body-centered cubic unit cell with an edge length of 3.165 \u00c5.\n"]], ["block_11", [" 82 . Platinum (atomic radius = 1.38 \u00c5) crystallizes in a cubic closely packed structure. Calculate the edge\n"]], ["block_12", [" 83 . Barium crystallizes in a body-centered cubic unit cell with an edge length of 5.025 \u00c5\n"]], ["block_13", [" 84 . Aluminum (atomic radius = 1.43 \u00c5) crystallizes in a cubic closely packed structure. Calculate the edge\n"]], ["block_14", [" 85 . The density of aluminum is 2.7 g/cm; that of silicon is 2.3 g/cm. Explain why Si has the lower density\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["Substance A is malleable, ductile, conducts electricity well, and has a melting point of 1135 \u00b0C. Substance\nB is brittle, does not conduct electricity as a solid but does when molten, and has a melting point of 2072\n\u00b0C. Substance C is very hard, does not conduct electricity, and has a melting point of 3440 \u00b0C. Substance D\nis soft, does not conduct electricity, and has a melting point of 185 \u00b0C.\n"]], ["block_17", ["(a) ionic solid\n(b) metallic solid\n(c) molecular solid\n(d) covalent network solid\n"]], ["block_18", ["(a) ionic solid\n(b) metallic solid\n(c) molecular solid\n(d) covalent network solid\n"]], ["block_19", ["cell.\n"]], ["block_20", ["cell.\n"]], ["block_21", ["cobalt atom?\n"]], ["block_22", ["atom?\n"]], ["block_23", ["(a) What is the atomic radius of tungsten in this structure?\n(b) Calculate the density of tungsten.\n"]], ["block_24", ["length of the face-centered cubic unit cell and the density of platinum.\n"]], ["block_25", ["(a) What is the atomic radius of barium in this structure?\n(b) Calculate the density of barium.\n"]], ["block_26", ["length of the face-centered cubic unit cell and the density of aluminum.\n"]], ["block_27", ["even though it has heavier atoms.\n"]], ["block_28", [" Substance \n Appearance \n Melting Point \n Electrical \n Conductivity \n Solubility in Water \n"]], ["block_29", ["X\nbrittle, white\n800 \u00b0C\nonly if melted/\n"]], ["block_30", ["Z\nhard, colorless\n3550 \u00b0C\nnone\ninsoluble\n"]], ["block_31", ["Y\nshiny, malleable\n1100 \u00b0C\nhigh\ninsoluble\n"]], ["block_32", ["dissolved\nsoluble\n"]]], "page_558": [["block_0", [" 86 . The free space in a metal may be found by subtracting the volume of the atoms in a unit cell from the\n"]], ["block_1", [" 87 . Cadmium sulfide, sometimes used as a yellow pigment by artists, crystallizes with cadmium, occupying\n"]], ["block_2", [" 88 . A compound of cadmium, tin, and phosphorus is used in the fabrication of some semiconductors. It\n"]], ["block_3", [" 89 . What is the formula of the magnetic oxide of cobalt, used in recording tapes, that crystallizes with cobalt\n"]], ["block_4", [" 90 . A compound containing zinc, aluminum, and sulfur crystallizes with a closest-packed array of sulfide\n"]], ["block_5", [" 91 . A compound of thallium and iodine crystallizes in a simple cubic array of iodide ions with thallium ions in\n"]], ["block_6", [" 92 . Which of the following elements reacts with sulfur to form a solid in which the sulfur atoms form a closest-\n"]], ["block_7", [" 93 . What is the percent by mass of titanium in rutile, a mineral that contains titanium and oxygen, if structure\n"]], ["block_8", [" 94 . Explain why the chemically similar alkali metal chlorides NaCl and CsCl have different structures,\n"]], ["block_9", [" 95 . As minerals were formed from the molten magma, different ions occupied the same cites in the crystals.\n"]], ["block_10", [" 96 . Rubidium iodide crystallizes with a cubic unit cell that contains iodide ions at the corners and a rubidium\n"]], ["block_11", [" 97 . One of the various manganese oxides crystallizes with a cubic unit cell that contains manganese ions at\n"]], ["block_12", [" 98 . NaH crystallizes with the same crystal structure as NaCl. The edge length of the cubic unit cell of NaH is\n"]], ["block_13", [" 99 . Thallium(I) iodide crystallizes with the same structure as CsCl. The edge length of the unit cell of TlI is\n"]], ["block_14", [" 100 . A cubic unit cell contains manganese ions at the corners and fluoride ions at the center of each edge.\n"]], ["block_15", [" 101 . What is the spacing between crystal planes that diffract X-rays with a wavelength of 1.541 nm at an angle\n"]], ["block_16", [" 102 . A diffractometer using X-rays with a wavelength of 0.2287 nm produced first order diffraction peak for a\n"]], ["block_17", [" 103 . A metal with spacing between planes equal to 0.4164 nm diffracts X-rays with a wavelength of 0.2879\n"]], ["block_18", ["volume of the cell. Calculate the percentage of free space in each of the three cubic lattices if all atoms in\neach are of equal size and touch their nearest neighbors. Which of these structures represents the most\nefficient packing? That is, which packs with the least amount of unused space?\n"]], ["block_19", ["one-half of the tetrahedral holes in a closest packed array of sulfide ions. What is the formula of cadmium\nsulfide? Explain your answer.\n"]], ["block_20", ["crystallizes with cadmium occupying one-fourth of the tetrahedral holes and tin occupying one-fourth of\nthe tetrahedral holes in a closest packed array of phosphide ions. What is the formula of the compound?\nExplain your answer.\n"]], ["block_21", ["atoms occupying one-eighth of the tetrahedral holes and one-half of the octahedral holes in a closely\npacked array of oxide ions?\n"]], ["block_22", ["ions. Zinc ions are found in one-eighth of the tetrahedral holes and aluminum ions in one-half of the\noctahedral holes. What is the empirical formula of the compound?\n"]], ["block_23", ["all of the cubic holes. What is the formula of this iodide? Explain your answer.\n"]], ["block_24", ["packed array with all of the octahedral holes occupied: Li, Na, Be, Ca, or Al?\n"]], ["block_25", ["can be described as a closest packed array of oxide ions with titanium ions in one-half of the octahedral\nholes? What is the oxidation number of titanium?\n"]], ["block_26", ["whereas the chemically different NaCl and MnS have the same structure.\n"]], ["block_27", ["Lithium often occurs along with magnesium in minerals despite the difference in the charge on their ions.\nSuggest an explanation.\n"]], ["block_28", ["ion in the center. What is the formula of the compound?\n"]], ["block_29", ["the corners and in the center. Oxide ions are located at the center of each edge of the unit cell. What is the\nformula of the compound?\n"]], ["block_30", ["4.880 \u00c5.\n(a) Calculate the ionic radius of H. (The ionic radius of Liis 0.0.95 \u00c5.)\n(b) Calculate the density of NaH.\n"]], ["block_31", ["4.20 \u00c5. Calculate the ionic radius of TI. (The ionic radius of Iis 2.16 \u00c5.)\n"]], ["block_32", ["\u03b8 of 15.55\u00b0 (first order reflection)?\n"]], ["block_33", ["(a) What is the empirical formula of this compound? Explain your answer.\n(b) What is the coordination number of the Mnion?\n(c) Calculate the edge length of the unit cell if the radius of a Mnion is 0.65 A.\n(d) Calculate the density of the compound.\n"]], ["block_34", ["crystal angle \u03b8 = 16.21\u00b0. Determine the spacing between the diffracting planes in this crystal.\n"]], ["block_35", ["nm. What is the diffraction angle for the first order diffraction peak?\n"]], ["block_36", [" 10 \u2022 Exercises \n 545 \n"]]], "page_559": [["block_0", [" 546 \n 10 \u2022 Exercises \n"]], ["block_1", [" 104 . Gold crystallizes in a face-centered cubic unit cell. The second-order reflection (n = 2) of X-rays for the\n"]], ["block_2", [" 105 . When an electron in an excited molybdenum atom falls from the L to the K shell, an X-ray is emitted.\n"]], ["block_3", [" Access for free at openstax.org \n"]], ["block_4", ["planes that make up the tops and bottoms of the unit cells is at \u03b8 = 22.20\u00b0. The wavelength of the X-rays\nis 1.54 \u00c5. What is the density of metallic gold?\n"]], ["block_5", ["These X-rays are diffracted at an angle of 7.75\u00b0 by planes with a separation of 2.64 \u00c5. What is the\ndifference in energy between the K shell and the L shell in molybdenum assuming a first order\ndiffraction?\n"]]], "page_560": [["block_0", ["CHAPTER 11\nSolutions and Colloids\n"]], ["block_1", [{"image_0": "560_0.png", "coords": [72, 104, 622, 346]}]], ["block_2", [" Figure 11.1 \nCoral reefs, such as this one at the Palmyra Atoll National Wildlife Refuge, are vital to the ecosystem of\n"]], ["block_3", ["earth\u2019s oceans. The health of coral reefs and all marine life depends on the specific chemical composition of the\ncomplex mixture known as seawater. (credit: modification of work by \u201cUSFWS \u2013 Pacific Region\u201d/Wikimedia\nCommons)\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 11.1 The Dissolution Process \n 11.2 Electrolytes \n 11.3 Solubility \n 11.4 Colligative Properties \n 11.5 Colloids \n"]], ["block_6", [" INTRODUCTION \n"]], ["block_7", ["climate change, oceanic acidification, and water pollution, all of which change the composition of the solution\nknown as seawater. Dissolved oxygen in seawater is critical for sea creatures, but as the oceans warm, oxygen\nbecomes less soluble. As the concentration of carbon dioxide in the atmosphere increases, the concentration of\ncarbon dioxide in the oceans increases, contributing to oceanic acidification. Coral reefs are particularly\nsensitive to the acidification of the ocean, since the exoskeletons of the coral polyps are soluble in acidic\nsolutions. Humans contribute to the changing of seawater composition by allowing agricultural runoff and\nother forms of pollution to affect our oceans.\n"]], ["block_8", ["Solutions are crucial to the processes that sustain life and to many other processes involving chemical\nreactions. This chapter considers the nature of solutions and examines factors that determine whether a\nsolution will form and what properties it may have. The properties of colloids\u2014mixtures containing dispersed\nparticles larger than the molecules and ions of typical solutions\u2014are also discussed.\n"]], ["block_9", ["Coral reefs are home to about 25% of all marine species. They are being threatened by\n"]]], "page_561": [["block_0", [" 548 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", ["The subscript \u201caq\u201d in the equation signifies that the sucrose molecules are solutes and are therefore\nindividually dispersed throughout the aqueous solution (water is the solvent). Although sucrose molecules are\nheavier than water molecules, they remain dispersed throughout the solution; gravity does not cause them to\n\u201csettle out\u201d over time.\n"]], ["block_2", [" 11.1 The Dissolution Process \n"]], ["block_3", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_4", ["An earlier chapter of this text introduced solutions, defined as homogeneous mixtures of two or more\nsubstances. Often, one component of a solution is present at a significantly greater concentration, in which\ncase it is called the solvent. The other components of the solution present in relatively lesser concentrations\nare called solutes. Sugar is a covalent solid composed of sucrose molecules, C12H22O11. When this compound\ndissolves in water, its molecules become uniformly distributed among the molecules of water:\n"]], ["block_5", ["Potassium dichromate, K2Cr2O7, is an ionic compound composed of colorless potassium ions, K, and orange\ndichromate ions,\nWhen a small amount of solid potassium dichromate is added to water, the\n"]], ["block_6", ["compound dissolves and dissociates to yield potassium ions and dichromate ions uniformly distributed\nthroughout the mixture (Figure 11.2), as indicated in this equation:\n"]], ["block_7", ["As with the mixture of sugar and water, this mixture is also an aqueous solution. Its solutes, potassium and\ndichromate ions, remain individually dispersed among the solvent (water) molecules.\n"]], ["block_8", [" FIGURE 11.2 \nWhen potassium dichromate (K2Cr2O7) is mixed with water, it forms a homogeneous orange solution.\n"]], ["block_9", ["(credit: modification of work by Mark Ott)\n"]], ["block_10", ["Visit this virtual lab (http://openstax.org/l/16Phetsugar) to view simulations of the dissolution of common\ncovalent and ionic substances (sugar and salt) in water.\n"]], ["block_11", ["Water is used so often as a solvent that the word solution has come to imply an aqueous solution to many\npeople. However, almost any gas, liquid, or solid can act as a solvent. Many alloys are solid solutions of one\nmetal dissolved in another; for example, US five-cent coins contain nickel dissolved in copper. Air is a gaseous\nsolution, a homogeneous mixture of nitrogen, oxygen, and several other gases. Oxygen (a gas), alcohol (a\nliquid), and sugar (a solid) all dissolve in water (a liquid) to form liquid solutions. Table 11.1 gives examples of\nseveral different solutions and the phases of the solutes and solvents.\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["\u2022\nDescribe the basic properties of solutions and how they form\n"]], ["block_14", ["\u2022\nPredict whether a given mixture will yield a solution based on molecular properties of its components\n"]], ["block_15", ["\u2022\nExplain why some solutions either produce or absorb heat when they form\n"]], ["block_16", ["LINK TO LEARNING\n"]], ["block_17", [{"image_0": "561_0.png", "coords": [130, 401, 481, 470]}]]], "page_562": [["block_0", ["Solutions exhibit these defining traits:\n"]], ["block_1", [" The Formation of Solutions \n"]], ["block_2", ["The formation of a solution is an example of a spontaneous process , a process that occurs under specified\nconditions without the requirement of energy from some external source. Sometimes a mixture is stirred to\nspeed up the dissolution process, but this is not necessary; a homogeneous solution will form eventually. The\ntopic of spontaneity is critically important to the study of chemical thermodynamics and is treated more\nthoroughly in a later chapter of this text. For purposes of this chapter\u2019s discussion, it will suffice to consider\ntwo criteria that favor, but do not guarantee, the spontaneous formation of a solution:\n"]], ["block_3", ["In the process of dissolution, an internal energy change often, but not always, occurs as heat is absorbed or\nevolved. An increase in matter dispersal always results when a solution forms from the uniform distribution of\nsolute molecules throughout a solvent.\n"]], ["block_4", ["When the strengths of the intermolecular forces of attraction between solute and solvent species in a solution\nare no different than those present in the separated components, the solution is formed with no accompanying\nenergy change. Such a solution is called an ideal solution . A mixture of ideal gases (or gases such as helium\nand argon, which closely approach ideal behavior) is an example of an ideal solution, since the entities\ncomprising these gases experience no significant intermolecular attractions.\n"]], ["block_5", ["1 If bubbles of gas are observed within the liquid, the mixture is not homogeneous and, thus, not a solution.\n"]], ["block_6", ["1.\na decrease in the internal energy of the system (an exothermic change, as discussed in the previous\nchapter on thermochemistry)\n"]], ["block_7", ["2.\nan increased dispersal of matter in the system (which indicates an increase in the entropy of the system,\nas you will learn about in the later chapter on thermodynamics)\n"]], ["block_8", ["\u2022\nThey are homogeneous; after a solution is mixed, it has the same composition at all points throughout (its\ncomposition is uniform).\n"]], ["block_9", ["\u2022\nThe physical state of a solution\u2014solid, liquid, or gas\u2014is typically the same as that of the solvent, as\ndemonstrated by the examples in Table 11.1.\n"]], ["block_10", ["\u2022\nThe components of a solution are dispersed on a molecular scale; they consist of a mixture of separated\nsolute particles (molecules, atoms, and/or ions) each closely surrounded by solvent species.\n"]], ["block_11", ["\u2022\nThe dissolved solute in a solution will not settle out or separate from the solvent.\n"]], ["block_12", ["\u2022\nThe composition of a solution, or the concentrations of its components, can be varied continuously (within\nlimits determined by the solubility of the components, discussed in detail later in this chapter).\n"]], ["block_13", [" TABLE 11.1 \n"]], ["block_14", [" Solution \n Solute \n Solvent \n"]], ["block_15", ["air\nO2(g)\nN2(g)\n"]], ["block_16", ["soft drinks\nCO2(g)\nH2O(l)\n"]], ["block_17", ["hydrogen in palladium\nH2(g)\nPd(s)\n"]], ["block_18", ["rubbing alcohol\nH2O(l)\nC3H8O(l) (2-propanol)\n"]], ["block_19", ["saltwater\nNaCl(s)\nH2O(l)\n"]], ["block_20", ["brass\nZn(s)\nCu(s)\n"]], ["block_21", ["Different Types of Solutions\n"]], ["block_22", [" 11.1 \u2022 The Dissolution Process \n 549 \n"]]], "page_563": [["block_0", [" 550 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", ["When containers of helium and argon are connected, the gases spontaneously mix due to diffusion and form a\nsolution (Figure 11.3). The formation of this solution clearly involves an increase in matter dispersal, since the\nhelium and argon atoms occupy a volume twice as large as that which each occupied before mixing.\n"]], ["block_2", [{"image_0": "563_0.png", "coords": [72, 101, 540, 221]}]], ["block_3", ["Ideal solutions may also form when structurally similar liquids are mixed. For example, mixtures of the\nalcohols methanol (CH3OH) and ethanol (C2H5OH) form ideal solutions, as do mixtures of the hydrocarbons\npentane, C5H12, and hexane, C6H14. Placing methanol and ethanol, or pentane and hexane, in the bulbs shown\nin Figure 11.3 will result in the same diffusion and subsequent mixing of these liquids as is observed for the\nHe and Ar gases (although at a much slower rate), yielding solutions with no significant change in energy.\nUnlike a mixture of gases, however, the components of these liquid-liquid solutions do, indeed, experience\nintermolecular attractive forces. But since the molecules of the two substances being mixed are structurally\nvery similar, the intermolecular attractive forces between like and unlike molecules are essentially the same,\nand the dissolution process, therefore, does not entail any appreciable increase or decrease in energy. These\nexamples illustrate how increased matter dispersal alone can provide the driving force required to cause the\nspontaneous formation of a solution. In some cases, however, the relative magnitudes of intermolecular forces\nof attraction between solute and solvent species may prevent dissolution.\n"]], ["block_4", ["Three types of intermolecular attractive forces are relevant to the dissolution process: solute-solute, solvent-\nsolvent, and solute-solvent. As illustrated in Figure 11.4, the formation of a solution may be viewed as a\nstepwise process in which energy is consumed to overcome solute-solute and solvent-solvent attractions\n(endothermic processes) and released when solute-solvent attractions are established (an exothermic process\nreferred to as solvation ). The relative magnitudes of the energy changes associated with these stepwise\nprocesses determine whether the dissolution process overall will release or absorb energy. In some cases,\nsolutions do not form because the energy required to separate solute and solvent species is so much greater\nthan the energy released by solvation.\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", [" FIGURE 11.3 \nSamples of helium and argon spontaneously mix to give a solution.\n"]]], "page_564": [["block_0", [{"image_0": "564_0.png", "coords": [72, 57, 540, 358]}]], ["block_1", [" FIGURE 11.4 \nThis schematic representation of dissolution shows a stepwise process involving the endothermic\n"]], ["block_2", ["separation of solute and solvent species (Steps 1 and 2) and exothermic solvation (Step 3).\n"]], ["block_3", ["Consider the example of an ionic compound dissolving in water. Formation of the solution requires the\nelectrostatic forces between the cations and anions of the compound (solute\u2013solute) be overcome completely\nas attractive forces are established between these ions and water molecules (solute\u2013solvent). Hydrogen\nbonding between a relatively small fraction of the water molecules must also be overcome to accommodate\nany dissolved solute. If the solute\u2019s electrostatic forces are significantly greater than the solvation forces, the\ndissolution process is significantly endothermic and the compound may not dissolve to an appreciable extent.\nCalcium carbonate, the major component of coral reefs, is one example of such an \u201cinsoluble\u201d ionic compound\n(see Figure 11.1). On the other hand, if the solvation forces are much stronger than the compound\u2019s\nelectrostatic forces, the dissolution is significantly exothermic and the compound may be highly soluble. A\ncommon example of this type of ionic compound is sodium chloride, commonly known as table salt.\n"]], ["block_4", ["As noted at the beginning of this module, spontaneous solution formation is favored, but not guaranteed, by\nexothermic dissolution processes. While many soluble compounds do, indeed, dissolve with the release of\nheat, some dissolve endothermically. Ammonium nitrate (NH4NO3) is one such example and is used to make\ninstant cold packs, like the one pictured in Figure 11.5, which are used for treating injuries. A thin-walled\nplastic bag of water is sealed inside a larger bag with solid NH4NO3. When the smaller bag is broken, a solution\nof NH4NO3 forms, absorbing heat from the surroundings (the injured area to which the pack is applied) and\nproviding a cold compress that decreases swelling. Endothermic dissolutions such as this one require a\ngreater energy input to separate the solute species than is recovered when the solutes are solvated, but they\nare spontaneous nonetheless due to the increase in disorder that accompanies formation of the solution.\n"]], ["block_5", [" 11.1 \u2022 The Dissolution Process \n 551 \n"]]], "page_565": [["block_0", [" 552 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", [" FIGURE 11.5 \nAn instant cold pack gets cold when certain salts, such as ammonium nitrate, dissolve in water\u2014an\n"]], ["block_2", ["endothermic process.\n"]], ["block_3", ["Watch this brief video (http://openstax.org/l/16endoexo) illustrating endothermic and exothermic dissolution\nprocesses.\n"]], ["block_4", [" 11.2 Electrolytes \n"]], ["block_5", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_6", ["When some substances are dissolved in water, they undergo either a physical or a chemical change that yields\nions in solution. These substances constitute an important class of compounds called electrolytes . Substances\nthat do not yield ions when dissolved are called nonelectrolytes . If the physical or chemical process that\ngenerates the ions is essentially 100% efficient (all of the dissolved compound yields ions), then the substance\nis known as a strong electrolyte . If only a relatively small fraction of the dissolved substance undergoes the\nion-producing process, it is called a weak electrolyte .\n"]], ["block_7", ["Substances may be identified as strong, weak, or nonelectrolytes by measuring the electrical conductance of\nan aqueous solution containing the substance. To conduct electricity, a substance must contain freely mobile,\ncharged species. Most familiar is the conduction of electricity through metallic wires, in which case the mobile,\ncharged entities are electrons. Solutions may also conduct electricity if they contain dissolved ions, with\nconductivity increasing as ion concentration increases. Applying a voltage to electrodes immersed in a\nsolution permits assessment of the relative concentration of dissolved ions, either quantitatively, by measuring\nthe electrical current flow, or qualitatively, by observing the brightness of a light bulb included in the circuit\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["\u2022\nDefine and give examples of electrolytes\n"]], ["block_10", ["\u2022\nDistinguish between the physical and chemical changes that accompany dissolution of ionic and covalent\nelectrolytes\n"]], ["block_11", ["\u2022\nRelate electrolyte strength to solute-solvent attractive forces\n"]], ["block_12", ["LINK TO LEARNING\n"]], ["block_13", [{"image_0": "565_0.png", "coords": [130, 57, 481, 345]}]]], "page_566": [["block_0", ["(Figure 11.6).\n"]], ["block_1", [{"image_0": "566_0.png", "coords": [72, 76, 540, 309]}]], ["block_2", [" FIGURE 11.6 \nSolutions of nonelectrolytes such as ethanol do not contain dissolved ions and cannot conduct\n"]], ["block_3", ["electricity. Solutions of electrolytes contain ions that permit the passage of electricity. The conductivity of an\nelectrolyte solution is related to the strength of the electrolyte.\n"]], ["block_4", [" Ionic Electrolytes \n"]], ["block_5", ["Water and other polar molecules are attracted to ions, as shown in Figure 11.7. The electrostatic attraction\nbetween an ion and a molecule with a dipole is called an ion-dipole attraction . These attractions play an\nimportant role in the dissolution of ionic compounds in water.\n"]], ["block_6", [" 11.2 \u2022 Electrolytes \n 553 \n"]]], "page_567": [["block_0", [" 554 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", [" FIGURE 11.7 \nAs potassium chloride (KCl) dissolves in water, the ions are hydrated. The polar water molecules are\n"]], ["block_2", ["attracted by the charges on the Kand Clions. Water molecules in front of and behind the ions are not shown.\n"]], ["block_3", ["When ionic compounds dissolve in water, the ions in the solid separate and disperse uniformly throughout the\nsolution because water molecules surround and solvate the ions, reducing the strong electrostatic forces\nbetween them. This process represents a physical change known as dissociation . Under most conditions, ionic\ncompounds will dissociate nearly completely when dissolved, and so they are classified as strong electrolytes.\nEven sparingly, soluble ionic compounds are strong electrolytes, since the small amount that does dissolve will\ndissociate completely.\n"]], ["block_4", ["Consider what happens at the microscopic level when solid KCl is added to water. Ion-dipole forces attract the\npositive (hydrogen) end of the polar water molecules to the negative chloride ions at the surface of the solid,\nand they attract the negative (oxygen) ends to the positive potassium ions. The water molecules surround\nindividual Kand Clions, reducing the strong interionic forces that bind the ions together and letting them\nmove off into solution as solvated ions, as Figure 11.7 shows. Overcoming the electrostatic attraction permits\nthe independent motion of each hydrated ion in a dilute solution as the ions transition from fixed positions in\nthe undissolved compound to widely dispersed, solvated ions in solution.\n"]], ["block_5", [" Covalent Electrolytes \n"]], ["block_6", ["Pure water is an extremely poor conductor of electricity because it is only very slightly ionized\u2014only about two\nout of every 1 billion molecules ionize at 25 \u00b0C. Water ionizes when one molecule of water gives up a proton (H\n"]], ["block_7", ["ion) to another molecule of water, yielding hydronium and hydroxide ions.\n"]], ["block_8", ["In some cases, solutions prepared from covalent compounds conduct electricity because the solute molecules\nreact chemically with the solvent to produce ions. For example, pure hydrogen chloride is a gas consisting of\ncovalent HCl molecules. This gas contains no ions. However, an aqueous solution of HCl is a very good\nconductor, indicating that an appreciable concentration of ions exists within the solution.\n"]], ["block_9", ["Because HCl is an acid, its molecules react with water, transferring Hions to form hydronium ions (H3O) and\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [{"image_0": "567_0.png", "coords": [130, 57, 481, 363]}]]], "page_568": [["block_0", ["chloride ions (Cl):\n"]], ["block_1", [{"image_0": "568_0.png", "coords": [72, 76, 423, 124]}]], ["block_2", ["This reaction is essentially 100% complete for HCl (i.e., it is a strong acid and, consequently, a strong\nelectrolyte). Likewise, weak acids and bases that only react partially generate relatively low concentrations of\nions when dissolved in water and are classified as weak electrolytes. The reader may wish to review the\ndiscussion of strong and weak acids provided in the earlier chapter of this text on reaction classes and\nstoichiometry.\n"]], ["block_3", [" 11.3 Solubility \n"]], ["block_4", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_5", ["Imagine adding a small amount of sugar to a glass of water, stirring until all the sugar has dissolved, and then\nadding a bit more. You can repeat this process until the sugar concentration of the solution reaches its natural\nlimit, a limit determined primarily by the relative strengths of the solute-solute, solute-solvent, and solvent-\nsolvent attractive forces discussed in the previous two modules of this chapter. You can be certain that you\nhave reached this limit because, no matter how long you stir the solution, undissolved sugar remains. The\nconcentration of sugar in the solution at this point is known as its solubility.\n"]], ["block_6", ["The solubility of a solute in a particular solvent is the maximum concentration that may be achieved under\ngiven conditions when the dissolution process is at equilibrium.\n"]], ["block_7", ["When a solute\u2019s concentration is equal to its solubility, the solution is said to be saturated with that solute. If\nthe solute\u2019s concentration is less than its solubility, the solution is said to be unsaturated . A solution that\ncontains a relatively low concentration of solute is called dilute, and one with a relatively high concentration is\ncalled concentrated.\n"]], ["block_8", ["Use this interactive simulation (http://openstax.org/l/16Phetsoluble) to prepare various saturated solutions.\n"]], ["block_9", ["Solutions may be prepared in which a solute concentration exceeds its solubility. Such solutions are said to be\n supersaturated , and they are interesting examples of nonequilibrium states (a detailed treatment of this\nimportant concept is provided in the text chapters on equilibrium). For example, the carbonated beverage in\nan open container that has not yet \u201cgone flat\u201d is supersaturated with carbon dioxide gas; given time, the CO2\nconcentration will decrease until it reaches its solubility.\n"]], ["block_10", ["Watch this impressive video (http://openstax.org/l/16NaAcetate) showing the precipitation of sodium acetate\nfrom a supersaturated solution.\n"]], ["block_11", [" Solutions of Gases in Liquids \n"]], ["block_12", ["As for any solution, the solubility of a gas in a liquid is affected by the intermolecular attractive forces between\nsolute and solvent species. Unlike solid and liquid solutes, however, there is no solute-solute intermolecular\nattraction to overcome when a gaseous solute dissolves in a liquid solvent (see Figure 11.4) since the atoms or\nmolecules comprising a gas are far separated and experience negligible interactions. Consequently, solute-\nsolvent interactions are the sole energetic factor affecting solubility. For example, the water solubility of\n"]], ["block_13", ["\u2022\nDescribe the effects of temperature and pressure on solubility\n"]], ["block_14", ["\u2022\nState Henry\u2019s law and use it in calculations involving the solubility of a gas in a liquid\n"]], ["block_15", ["\u2022\nExplain the degrees of solubility possible for liquid-liquid solutions\n"]], ["block_16", ["LINK TO LEARNING\n"]], ["block_17", ["LINK TO LEARNING\n"]], ["block_18", [" 11.3 \u2022 Solubility \n 555 \n"]]], "page_569": [["block_0", [" 556 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", ["oxygen is approximately three times greater than that of helium (there are greater dispersion forces between\nwater and the larger oxygen molecules) but 100 times less than the solubility of chloromethane, CHCl3 (polar\nchloromethane molecules experience dipole\u2013dipole attraction to polar water molecules). Likewise note the\nsolubility of oxygen in hexane, C6H14, is approximately 20 times greater than it is in water because greater\ndispersion forces exist between oxygen and the larger hexane molecules.\n"]], ["block_2", ["Temperature is another factor affecting solubility, with gas solubility typically decreasing as temperature\nincreases (Figure 11.8). This inverse relation between temperature and dissolved gas concentration is\nresponsible for one of the major impacts of thermal pollution in natural waters.\n"]], ["block_3", [" FIGURE 11.8 \nThe solubilities of these gases in water decrease as the temperature increases. All solubilities were\n"]], ["block_4", ["measured with a constant pressure of 101.3 kPa (1 atm) of gas above the solutions.\n"]], ["block_5", ["When the temperature of a river, lake, or stream is raised, the solubility of oxygen in the water is decreased.\nDecreased levels of dissolved oxygen may have serious consequences for the health of the water\u2019s ecosystems\nand, in severe cases, can result in large-scale fish kills (Figure 11.9).\n"]], ["block_6", [{"image_0": "569_0.png", "coords": [72, 493, 540, 656]}]], ["block_7", [" FIGURE 11.9 \n(a) The small bubbles of air in this glass of chilled water formed when the water warmed to room\n"]], ["block_8", ["temperature and the solubility of its dissolved air decreased. (b) The decreased solubility of oxygen in natural\nwaters subjected to thermal pollution can result in large-scale fish kills. (credit a: modification of work by Liz West;\ncredit b: modification of work by U.S. Fish and Wildlife Service)\n"]], ["block_9", ["The solubility of a gaseous solute is also affected by the partial pressure of solute in the gas to which the\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [{"image_1": "569_1.png", "coords": [189, 171, 423, 414]}]]], "page_570": [["block_0", ["where k is a proportionality constant that depends on the identities of the gaseous solute and solvent, and on\nthe solution temperature. This is a mathematical statement of Henry\u2019s law : The quantity of an ideal gas that\ndissolves in a definite volume of liquid is directly proportional to the pressure of the gas.\n"]], ["block_1", ["solution is exposed. Gas solubility increases as the pressure of the gas increases. Carbonated beverages\nprovide a nice illustration of this relationship. The carbonation process involves exposing the beverage to a\nrelatively high pressure of carbon dioxide gas and then sealing the beverage container, thus saturating the\nbeverage with CO2 at this pressure. When the beverage container is opened, a familiar hiss is heard as the\ncarbon dioxide gas pressure is released, and some of the dissolved carbon dioxide is typically seen leaving\nsolution in the form of small bubbles (Figure 11.10). At this point, the beverage is supersaturated with carbon\ndioxide and, with time, the dissolved carbon dioxide concentration will decrease to its equilibrium value and\nthe beverage will become \u201cflat.\u201d\n"]], ["block_2", [" FIGURE 11.10 \nOpening the bottle of carbonated beverage reduces the pressure of the gaseous carbon dioxide\n"]], ["block_3", ["above the beverage. The solubility of CO2 is thus lowered, and some dissolved carbon dioxide may be seen leaving\nthe solution as small gas bubbles. (credit: modification of work by Derrick Coetzee)\n"]], ["block_4", ["For many gaseous solutes, the relation between solubility, Cg, and partial pressure, Pg, is a proportional one:\n"]], ["block_5", [" Application of Henry\u2019s Law \n"]], ["block_6", ["At 20 \u00b0C, the concentration of dissolved oxygen in water exposed to gaseous oxygen at a partial pressure of\n101.3 kPa is 1.38\n10mol L. Use Henry\u2019s law to determine the solubility of oxygen when its partial\n"]], ["block_7", ["pressure is 20.7 kPa, the approximate pressure of oxygen in earth\u2019s atmosphere.\n"]], ["block_8", [" Solution \n"]], ["block_9", ["According to Henry\u2019s law, for an ideal solution the solubility, Cg, of a gas (1.38\n10mol L, in this case) is\n"]], ["block_10", ["directly proportional to the pressure, Pg, of the undissolved gas above the solution (101.3 kPa in this case).\nBecause both Cg and Pg are known, this relation can be rearragned and used to solve for k.\n"]], ["block_11", ["EXAMPLE 11.1\n"]], ["block_12", [{"image_0": "570_0.png", "coords": [130, 164, 481, 405]}]], ["block_13", [" 11.3 \u2022 Solubility \n 557 \n"]]], "page_571": [["block_0", [" 558 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", ["Now, use k to find the solubility at the lower pressure.\n"]], ["block_2", ["Note that various units may be used to express the quantities involved in these sorts of computations. Any\ncombination of units that yield to the constraints of dimensional analysis are acceptable.\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["Exposing a 100.0 mL sample of water at 0 \u00b0C to an atmosphere containing a gaseous solute at 152 torr resulted\nin the dissolution of 1.45\n10g of the solute. Use Henry\u2019s law to determine the solubility of this gaseous\n"]], ["block_5", ["solute when its pressure is 760 torr.\n"]], ["block_6", [" Answer: \n7.25\n10in 100.0 mL or 0.0725 g/L\n"]], ["block_7", [" Thermal Pollution and Oxygen Solubility \n"]], ["block_8", ["A certain species of freshwater trout requires a dissolved oxygen concentration of 7.5 mg/L. Could these fish\nthrive in a thermally polluted mountain stream (water temperature is 30.0 \u00b0C, partial pressure of atmospheric\noxygen is 0.17 atm)? Use the data in Figure 11.8 to estimate a value for the Henry's law constant at this\ntemperature.\n"]], ["block_9", [" Solution \n"]], ["block_10", ["First, estimate the Henry\u2019s law constant for oxygen in water at the specified temperature of 30.0 \u00b0C (Figure\n11.8 indicates the solubility at this temperature is approximately ~1.2 mol/L).\n"]], ["block_11", ["Then, use this k value to compute the oxygen solubility at the specified oxygen partial pressure, 0.17 atm.\n"]], ["block_12", ["Finally, convert this dissolved oxygen concentration from mol/L to mg/L.\n"]], ["block_13", ["This concentration is lesser than the required minimum value of 7.5 mg/L, and so these trout would likely not\nthrive in the polluted stream.\n"]], ["block_14", [" Check Your Learning \n"]], ["block_15", ["What dissolved oxygen concentration is expected for the stream above when it returns to a normal summer\ntime temperature of 15 \u00b0C?\n"]], ["block_16", [" Answer: \n8.2 mg/L\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["EXAMPLE 11.2\n"]]], "page_572": [["block_0", ["Deviations from Henry\u2019s law are observed when a chemical reaction takes place between the gaseous solute\nand the solvent. Thus, for example, the solubility of ammonia in water increases more rapidly with increasing\npressure than predicted by the law because ammonia, being a base, reacts to some extent with water to form\nammonium ions and hydroxide ions.\n"]], ["block_1", [{"image_0": "572_0.png", "coords": [72, 600, 423, 668]}]], ["block_2", ["Gases can form supersaturated solutions. If a solution of a gas in a liquid is prepared either at low temperature\nor under pressure (or both), then as the solution warms or as the gas pressure is reduced, the solution may\nbecome supersaturated. In 1986, more than 1700 people in Cameroon were killed when a cloud of gas, almost\ncertainly carbon dioxide, bubbled from Lake Nyos (Figure 11.12), a deep lake in a volcanic crater. The water at\nthe bottom of Lake Nyos is saturated with carbon dioxide by volcanic activity beneath the lake. It is believed\n"]], ["block_3", ["Chemistry in Everyday Life\n"]], ["block_4", [" Decompression Sickness or \u201cThe Bends\u201d \nDecompression sickness (DCS), or \u201cthe bends,\u201d is an effect of the increased pressure of the air inhaled by\nscuba divers when swimming underwater at considerable depths. In addition to the pressure exerted by\nthe atmosphere, divers are subjected to additional pressure due to the water above them, experiencing an\nincrease of approximately 1 atm for each 10 m of depth. Therefore, the air inhaled by a diver while\nsubmerged contains gases at the corresponding higher ambient pressure, and the concentrations of the\ngases dissolved in the diver\u2019s blood are proportionally higher per Henry\u2019s law.\n"]], ["block_5", ["As the diver ascends to the surface of the water, the ambient pressure decreases and the dissolved gases\nbecomes less soluble. If the ascent is too rapid, the gases escaping from the diver\u2019s blood may form bubbles\nthat can cause a variety of symptoms ranging from rashes and joint pain to paralysis and death. To avoid\nDCS, divers must ascend from depths at relatively slow speeds (10 or 20 m/min) or otherwise make several\ndecompression stops, pausing for several minutes at given depths during the ascent. When these\npreventive measures are unsuccessful, divers with DCS are often provided hyperbaric oxygen therapy in\npressurized vessels called decompression (or recompression) chambers (Figure 11.11). Researchers are\nalso investigating related body reactions and defenses in order to develop better testing and treatment for\ndecompression sicknetss. For example, Ingrid Eftedal, a barophysiologist specializing in bodily reactions\nto diving, has shown that white blood cells undergo chemical and genetic changes as a result of the\ncondition; these can potentially be used to create biomarker tests and other methods to manage\ndecompression sickness.\n"]], ["block_6", [" FIGURE 11.11 \n(a) US Navy divers undergo training in a recompression chamber. (b) Divers receive hyperbaric\n"]], ["block_7", ["oxygen therapy.\n"]], ["block_8", [{"image_1": "572_1.png", "coords": [130, 338, 481, 488]}]], ["block_9", [" 11.3 \u2022 Solubility \n 559 \n"]]], "page_573": [["block_0", [" 560 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", ["that the lake underwent a turnover due to gradual heating from below the lake, and the warmer, less-dense\nwater saturated with carbon dioxide reached the surface. Consequently, tremendous quantities of dissolved\nCO2 were released, and the colorless gas, which is denser than air, flowed down the valley below the lake and\nsuffocated humans and animals living in the valley.\n"]], ["block_2", [{"image_0": "573_0.png", "coords": [72, 114, 540, 287]}]], ["block_3", [" FIGURE 11.12 \n(a) It is believed that the 1986 disaster that killed more than 1700 people near Lake Nyos in\n"]], ["block_4", ["Cameroon resulted when a large volume of carbon dioxide gas was released from the lake. (b) A CO2 vent has since\nbeen installed to help outgas the lake in a slow, controlled fashion and prevent a similar catastrophe from\nhappening in the future. (credit a: modification of work by Jack Lockwood; credit b: modification of work by Bill\nEvans)\n"]], ["block_5", [" Solutions of Liquids in Liquids \n"]], ["block_6", ["Some liquids may be mixed in any proportions to yield solutions; in other words, they have infinite mutual\nsolubility and are said to be miscible . Ethanol, sulfuric acid, and ethylene glycol (popular for use as antifreeze,\npictured in Figure 11.13) are examples of liquids that are completely miscible with water. Two-cycle motor oil\nis miscible with gasoline, mixtures of which are used as lubricating fuels for various types of outdoor power\nequipment (chainsaws, leaf blowers, and so on).\n"]], ["block_7", [" Access for free at openstax.org \n"]]], "page_574": [["block_0", [" FIGURE 11.13 \nWater and antifreeze are miscible; mixtures of the two are homogeneous in all proportions. (credit:\n"]], ["block_1", ["\u201cdno1967\u201d/Wikimedia commons)\n"]], ["block_2", ["Miscible liquids are typically those with very similar polarities. Consider, for example, liquids that are polar or\ncapable of hydrogen bonding. For such liquids, the dipole-dipole attractions (or hydrogen bonding) of the\nsolute molecules with the solvent molecules are at least as strong as those between molecules in the pure\nsolute or in the pure solvent. Hence, the two kinds of molecules mix easily. Likewise, nonpolar liquids are\nmiscible with each other because there is no appreciable difference in the strengths of solute-solute, solvent-\nsolvent, and solute-solvent intermolecular attractions. The solubility of polar molecules in polar solvents and\nof nonpolar molecules in nonpolar solvents is, again, an illustration of the chemical axiom \u201clike dissolves like.\u201d\n"]], ["block_3", ["Two liquids that do not mix to an appreciable extent are called immiscible . Separate layers are formed when\nimmiscible liquids are poured into the same container. Gasoline, oil (Figure 11.14), benzene, carbon\ntetrachloride, some paints, and many other nonpolar liquids are immiscible with water. Relatively weak\nattractive forces between the polar water molecules and the nonpolar liquid molecules are not adequate to\novercome much stronger hydrogen bonding between water molecules. The distinction between immiscibility\nand miscibility is really one of extent, so that miscible liquids are of infinite mutual solubility, while liquids\nsaid to be immiscible are of very low (though not zero) mutual solubility.\n"]], ["block_4", [{"image_0": "574_0.png", "coords": [195, 57, 416, 333]}]], ["block_5", [" 11.3 \u2022 Solubility \n 561 \n"]]], "page_575": [["block_0", [" 562 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", [" FIGURE 11.14 \nWater and oil are immiscible. Mixtures of these two substances will form two separate layers with\n"]], ["block_2", ["the less dense oil floating on top of the water. (credit: \u201cYortw\u201d/Flickr)\n"]], ["block_3", ["Two liquids, such as bromine and water, that are of moderate mutual solubility are said to be partially \n miscible . Two partially miscible liquids usually form two layers when mixed. In the case of the bromine and\nwater mixture, the upper layer is water, saturated with bromine, and the lower layer is bromine saturated with\nwater. Since bromine is nonpolar, and, thus, not very soluble in water, the water layer is only slightly discolored\nby the bright orange bromine dissolved in it. Since the solubility of water in bromine is very low, there is no\nnoticeable effect on the dark color of the bromine layer (Figure 11.15).\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", [{"image_0": "575_0.png", "coords": [189, 57, 423, 395]}]]], "page_576": [["block_0", [" FIGURE 11.15 \nBromine (the deep orange liquid on the left) and water (the clear liquid in the middle) are partially\n"]], ["block_1", ["miscible. The top layer in the mixture on the right is a saturated solution of bromine in water; the bottom layer is a\nsaturated solution of water in bromine. (credit: Paul Flowers)\n"]], ["block_2", [" Solutions of Solids in Liquids \n"]], ["block_3", ["The dependence of solubility on temperature for a number of solids in water is shown by the solubility curves\nin Figure 11.16. Reviewing these data indicates a general trend of increasing solubility with temperature,\nalthough there are exceptions, as illustrated by the ionic compound cerium sulfate.\n"]], ["block_4", [" FIGURE 11.16 \nThis graph shows how the solubility of several solids changes with temperature.\n"]], ["block_5", [{"image_0": "576_0.png", "coords": [189, 57, 423, 307]}]], ["block_6", [{"image_1": "576_1.png", "coords": [189, 418, 423, 713]}]], ["block_7", [" 11.3 \u2022 Solubility \n 563 \n"]]], "page_577": [["block_0", [" 564 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", ["The properties of a solution are different from those of either the pure solute(s) or solvent. Many solution\nproperties are dependent upon the chemical identity of the solute. Compared to pure water, a solution of\nhydrogen chloride is more acidic, a solution of ammonia is more basic, a solution of sodium chloride is more\ndense, and a solution of sucrose is more viscous. There are a few solution properties, however, that depend\nonly upon the total concentration of solute species, regardless of their identities. These colligative properties \ninclude vapor pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure.\nThis small set of properties is of central importance to many natural phenomena and technological\napplications, as will be described in this module.\n"]], ["block_2", ["The temperature dependence of solubility can be exploited to prepare supersaturated solutions of certain\ncompounds. A solution may be saturated with the compound at an elevated temperature (where the solute is\nmore soluble) and subsequently cooled to a lower temperature without precipitating the solute. The resultant\nsolution contains solute at a concentration greater than its equilibrium solubility at the lower temperature (i.e.,\nit is supersaturated) and is relatively stable. Precipitation of the excess solute can be initiated by adding a seed\ncrystal (see the video in the Link to Learning earlier in this module) or by mechanically agitating the solution.\nSome hand warmers, such as the one pictured in Figure 11.17, take advantage of this behavior.\n"]], ["block_3", [" FIGURE 11.17 \nThis hand warmer produces heat when the sodium acetate in a supersaturated solution\n"]], ["block_4", ["precipitates. Precipitation of the solute is initiated by a mechanical shockwave generated when the flexible metal\ndisk within the solution is \u201cclicked.\u201d (credit: modification of work by \u201cVelela\u201d/Wikimedia Commons)\n"]], ["block_5", ["This video (http://openstax.org/l/16handwarmer) shows the crystallization process occurring in a hand\nwarmer.\n"]], ["block_6", [" 11.4 Colligative Properties \n"]], ["block_7", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_8", [" Mole Fraction and Molality \n"]], ["block_9", ["Several units commonly used to express the concentrations of solution components were introduced in an\nearlier chapter of this text, each providing certain benefits for use in different applications. For example,\nmolarity (M) is a convenient unit for use in stoichiometric calculations, since it is defined in terms of the molar\namounts of solute species:\n"]], ["block_10", ["Because solution volumes vary with temperature, molar concentrations will likewise vary. When expressed as\nmolarity, the concentration of a solution with identical numbers of solute and solvent species will be different\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["\u2022\nExpress concentrations of solution components using mole fraction and molality\n"]], ["block_13", ["\u2022\nDescribe the effect of solute concentration on various solution properties (vapor pressure, boiling point,\nfreezing point, and osmotic pressure)\n"]], ["block_14", ["\u2022\nPerform calculations using the mathematical equations that describe these various colligative effects\n"]], ["block_15", ["\u2022\nDescribe the process of distillation and its practical applications\n"]], ["block_16", ["\u2022\nExplain the process of osmosis and describe how it is applied industrially and in nature\n"]], ["block_17", [{"image_0": "577_0.png", "coords": [90, 152, 522, 241]}]], ["block_18", ["LINK TO LEARNING\n"]]], "page_578": [["block_0", ["at different temperatures, due to the contraction/expansion of the solution. More appropriate for calculations\ninvolving many colligative properties are mole-based concentration units whose values are not dependent on\ntemperature. Two such units are mole fraction (introduced in the previous chapter on gases) and molality.\n"]], ["block_1", ["The mole fraction, X, of a component is the ratio of its molar amount to the total number of moles of all\nsolution components:\n"]], ["block_2", ["By this definition, the sum of mole fractions for all solution components (the solvent and all solutes) is equal to\none.\n"]], ["block_3", [" Molality is a concentration unit defined as the ratio of the numbers of moles of solute to the mass of the solvent\nin kilograms:\n"]], ["block_4", ["Since these units are computed using only masses and molar amounts, they do not vary with temperature and,\nthus, are better suited for applications requiring temperature-independent concentrations, including several\ncolligative properties, as will be described in this chapter module.\n"]], ["block_5", [" Calculating Mole Fraction and Molality \n"]], ["block_6", ["The antifreeze in most automobile radiators is a mixture of equal volumes of ethylene glycol and water, with\nminor amounts of other additives that prevent corrosion. What are the (a) mole fraction and (b) molality of\nethylene glycol, C2H4(OH)2, in a solution prepared from 2.22\n10g of ethylene glycol and 2.00\n10g of water\n"]], ["block_7", ["(approximately 2 L of glycol and 2 L of water)?\n"]], ["block_8", [" Solution \n"]], ["block_9", ["(a) The mole fraction of ethylene glycol may be computed by first deriving molar amounts of both solution\ncomponents and then substituting these amounts into the definition of mole fraction.\n"]], ["block_10", ["Notice that mole fraction is a dimensionless property, being the ratio of properties with identical units (moles).\n"]], ["block_11", ["(b) Derive moles of solute and mass of solvent (in kg).\n"]], ["block_12", ["First, use the given mass of ethylene glycol and its molar mass to find the moles of solute:\n"]], ["block_13", ["Then, convert the mass of the water from grams to kilograms:\n"]], ["block_14", ["Finally, calculate molality per its definition:\n"]], ["block_15", ["EXAMPLE 11.3\n"]], ["block_16", [" 11.4 \u2022 Colligative Properties \n 565 \n"]]], "page_579": [["block_0", [" 566 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["What are the mole fraction and molality of a solution that contains 0.850 g of ammonia, NH3, dissolved in 125\ng of water?\n"]], ["block_3", [" Answer: \n7.14\n10; 0.399 m\n"]], ["block_4", [" Converting Mole Fraction and Molal Concentrations \n"]], ["block_5", ["Calculate the mole fraction of solute and solvent in a 3.0 m solution of sodium chloride.\n"]], ["block_6", [" Solution \n"]], ["block_7", ["Converting from one concentration unit to another is accomplished by first comparing the two unit definitions.\nIn this case, both units have the same numerator (moles of solute) but different denominators. The provided\nmolal concentration may be written as:\n"]], ["block_8", ["The numerator for this solution\u2019s mole fraction is, therefore, 3.0 mol NaCl. The denominator may be computed\nby deriving the molar amount of water corresponding to 1.0 kg\n"]], ["block_9", ["and then substituting these molar amounts into the definition for mole fraction.\n"]], ["block_10", [" Check Your Learning \n"]], ["block_11", ["The mole fraction of iodine, I2, dissolved in dichloromethane, CH2Cl2, is 0.115. What is the molal\nconcentration, m, of iodine in this solution?\n"]], ["block_12", [" Answer: \n1.50 m\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", ["EXAMPLE 11.4\n"]]], "page_580": [["block_0", [" Molality and Molarity Conversions \n"]], ["block_1", ["Intravenous infusion of a 0.556 M aqueous solution of glucose (density of 1.04 g/mL) is part of some post-\noperative recovery therapies. What is the molal concentration of glucose in this solution?\n"]], ["block_2", [" Solution \n"]], ["block_3", ["The provided molal concentration may be explicitly written as:\n"]], ["block_4", ["Consider the definition of molality:\n"]], ["block_5", ["The amount of glucose in 1-L of this solution is 0.556 mol, so the mass of water in this volume of solution is\nneeded.\n"]], ["block_6", ["First, compute the mass of 1.00 L of the solution:\n"]], ["block_7", ["This is the mass of both the water and its solute, glucose, and so the mass of glucose must be subtracted.\nCompute the mass of glucose from its molar amount:\n"]], ["block_8", ["Subtracting the mass of glucose yields the mass of water in the solution:\n"]], ["block_9", ["Finally, the molality of glucose in this solution is computed as:\n"]], ["block_10", [" Check Your Learning \n"]], ["block_11", ["Nitric acid, HNO3(aq), is commercially available as a 33.7 m aqueous solution (density = 1.35 g/mL). What is\nthe molarity of this solution?\n"]], ["block_12", [" Answer: \n14.6 M\n"]], ["block_13", [" Vapor Pressure Lowering \n"]], ["block_14", ["As described in the chapter on liquids and solids, the equilibrium vapor pressure of a liquid is the pressure\nexerted by its gaseous phase when vaporization and condensation are occurring at equal rates:\n"]], ["block_15", ["Dissolving a nonvolatile substance in a volatile liquid results in a lowering of the liquid\u2019s vapor pressure. This\nphenomenon can be rationalized by considering the effect of added solute molecules on the liquid's\nvaporization and condensation processes. To vaporize, solvent molecules must be present at the surface of the\nsolution. The presence of solute decreases the surface area available to solvent molecules and thereby reduces\nthe rate of solvent vaporization. Since the rate of condensation is unaffected by the presence of solute, the net\nresult is that the vaporization-condensation equilibrium is achieved with fewer solvent molecules in the vapor\nphase (i.e., at a lower vapor pressure) (Figure 11.18). While this interpretation is useful, it does not account for\nseveral important aspects of the colligative nature of vapor pressure lowering. A more rigorous explanation\ninvolves the property of entropy, a topic of discussion in a later text chapter on thermodynamics. For purposes\nof understanding the lowering of a liquid's vapor pressure, it is adequate to note that the more dispersed\nnature of matter in a solution, compared to separate solvent and solute phases, serves to effectively stabilize\nthe solvent molecules and hinder their vaporization. A lower vapor pressure results, and a correspondingly\n"]], ["block_16", ["EXAMPLE 11.5\n"]], ["block_17", [" 11.4 \u2022 Colligative Properties \n 567 \n"]]], "page_581": [["block_0", [" 568 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", ["The relationship between the vapor pressures of solution components and the concentrations of those\ncomponents is described by Raoult\u2019s law : The partial pressure exerted by any component of an ideal solution\nis equal to the vapor pressure of the pure component multiplied by its mole fraction in the solution.\n"]], ["block_2", ["higher boiling point as described in the next section of this module.\n"]], ["block_3", [{"image_0": "581_0.png", "coords": [72, 76, 540, 397]}]], ["block_4", [" FIGURE 11.18 \nThe presence of nonvolatile solutes lowers the vapor pressure of a solution by impeding the\n"]], ["block_5", ["evaporation of solvent molecules.\n"]], ["block_6", ["where PA is the partial pressure exerted by component A in the solution,\nis the vapor pressure of pure A,\n"]], ["block_7", ["and XA is the mole fraction of A in the solution.\n"]], ["block_8", ["Recalling that the total pressure of a gaseous mixture is equal to the sum of partial pressures for all its\ncomponents (Dalton\u2019s law of partial pressures), the total vapor pressure exerted by a solution containing i\ncomponents is\n"]], ["block_9", ["A nonvolatile substance is one whose vapor pressure is negligible (P* \u2248 0), and so the vapor pressure above a\nsolution containing only nonvolatile solutes is due only to the solvent:\n"]], ["block_10", [" Calculation of a Vapor Pressure \n"]], ["block_11", ["Compute the vapor pressure of an ideal solution containing 92.1 g of glycerin, C3H5(OH)3, and 184.4 g of\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["EXAMPLE 11.6\n"]]], "page_582": [["block_0", ["ethanol, C2H5OH, at 40 \u00b0C. The vapor pressure of pure ethanol is 0.178 atm at 40 \u00b0C. Glycerin is essentially\nnonvolatile at this temperature.\n"]], ["block_1", [" Solution \n"]], ["block_2", ["Since the solvent is the only volatile component of this solution, its vapor pressure may be computed per\nRaoult\u2019s law as:\n"]], ["block_3", ["First, calculate the molar amounts of each solution component using the provided mass data.\n"]], ["block_4", ["Next, calculate the mole fraction of the solvent (ethanol) and use Raoult\u2019s law to compute the solution\u2019s vapor\npressure.\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["A solution contains 5.00 g of urea, CO(NH2)2 (a nonvolatile solute) and 0.100 kg of water. If the vapor pressure\nof pure water at 25 \u00b0C is 23.7 torr, what is the vapor pressure of the solution assuming ideal behavior?\n"]], ["block_7", [" Answer: \n23.4 torr\n"]], ["block_8", [" Distillation of Solutions \n"]], ["block_9", ["Solutions whose components have significantly different vapor pressures may be separated by a selective\nvaporization process known as distillation. Consider the simple case of a mixture of two volatile liquids, A and\nB, with A being the more volatile liquid. Raoult\u2019s law can be used to show that the vapor above the solution is\nenriched in component A, that is, the mole fraction of A in the vapor is greater than the mole fraction of A in\nthe liquid (see end-of-chapter Exercise 65). By appropriately heating the mixture, component A may be\nvaporized, condensed, and collected\u2014effectively separating it from component B.\n"]], ["block_10", ["Distillation is widely applied in both laboratory and industrial settings, being used to refine petroleum, to\nisolate fermentation products, and to purify water. A typical apparatus for laboratory-scale distillations is\nshown in Figure 11.19.\n"]], ["block_11", [" 11.4 \u2022 Colligative Properties \n 569 \n"]]], "page_583": [["block_0", [" 570 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", [{"image_0": "583_0.png", "coords": [72, 57, 540, 371]}]], ["block_2", [" FIGURE 11.19 \nA typical laboratory distillation unit is shown in (a) a photograph and (b) a schematic diagram of the\n"]], ["block_3", ["components. (credit a: modification of work by \u201cRifleman82\u201d/Wikimedia commons; credit b: modification of work by\n\u201cSlashme\u201d/Wikimedia Commons)\n"]], ["block_4", ["Oil refineries use large-scale fractional distillation to separate the components of crude oil. The crude oil is\nheated to high temperatures at the base of a tall fractionating column, vaporizing many of the components that\nrise within the column. As vaporized components reach adequately cool zones during their ascent, they\ncondense and are collected. The collected liquids are simpler mixtures of hydrocarbons and other petroleum\ncompounds that are of appropriate composition for various applications (e.g., diesel fuel, kerosene, gasoline),\nas depicted in Figure 11.20.\n"]], ["block_5", [" Access for free at openstax.org \n"]]], "page_584": [["block_0", [{"image_0": "584_0.png", "coords": [72, 57, 540, 383]}]], ["block_1", [" FIGURE 11.20 \nCrude oil is a complex mixture that is separated by large-scale fractional distillation to isolate\n"]], ["block_2", ["various simpler mixtures.\n"]], ["block_3", [" Boiling Point Elevation \n"]], ["block_4", ["As described in the chapter on liquids and solids, the boiling point of a liquid is the temperature at which its\nvapor pressure is equal to ambient atmospheric pressure. Since the vapor pressure of a solution is lowered due\nto the presence of nonvolatile solutes, it stands to reason that the solution\u2019s boiling point will subsequently be\nincreased. Vapor pressure increases with temperature, and so a solution will require a higher temperature\nthan will pure solvent to achieve any given vapor pressure, including one equivalent to that of the surrounding\natmosphere. The increase in boiling point observed when nonvolatile solute is dissolved in a solvent, \u0394Tb, is\ncalled boiling point elevation and is directly proportional to the molal concentration of solute species:\n"]], ["block_5", ["where Kb is the boiling point elevation constant , or the ebullioscopic constant and m is the molal\nconcentration (molality) of all solute species.\n"]], ["block_6", ["Boiling point elevation constants are characteristic properties that depend on the identity of the solvent.\nValues of Kb for several solvents are listed in Table 11.2.\n"]], ["block_7", [" TABLE 11.2 \n"]], ["block_8", [" Solvent \n Boiling Point (\u00b0C at 1 atm) \n K b (\u00baCm \u22121 ) \n Freezing Point (\u00b0C at 1 atm) \n K f (\u00baCm \u22121 ) \n"]], ["block_9", ["water\n100.0\n0.512\n0.0\n1.86\n"]], ["block_10", ["Boiling Point Elevation and Freezing Point Depression Constants for Several Solvents\n"]], ["block_11", [" 11.4 \u2022 Colligative Properties \n 571 \n"]]], "page_585": [["block_0", [" 572 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", ["The extent to which the vapor pressure of a solvent is lowered and the boiling point is elevated depends on the\ntotal number of solute particles present in a given amount of solvent, not on the mass or size or chemical\nidentities of the particles. A 1 m aqueous solution of sucrose (342 g/mol) and a 1 m aqueous solution of\nethylene glycol (62 g/mol) will exhibit the same boiling point because each solution has one mole of solute\nparticles (molecules) per kilogram of solvent.\n"]], ["block_2", [" Calculating the Boiling Point of a Solution \n"]], ["block_3", ["Assuming ideal solution behavior, what is the boiling point of a 0.33 m solution of a nonvolatile solute in\nbenzene?\n"]], ["block_4", [" Solution \n"]], ["block_5", ["Use the equation relating boiling point elevation to solute molality to solve this problem in two steps.\n"]], ["block_6", [{"image_0": "585_0.png", "coords": [72, 402, 423, 465]}]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["Assuming ideal solution behavior, what is the boiling point of the antifreeze described in Example 11.3?\n"]], ["block_9", [" Answer: \n109.2 \u00b0C\n"]], ["block_10", [" The Boiling Point of an Iodine Solution \n"]], ["block_11", ["Find the boiling point of a solution of 92.1 g of iodine, I2, in 800.0 g of chloroform, CHCl3, assuming that the\niodine is nonvolatile and that the solution is ideal.\n"]], ["block_12", [" Solution \n"]], ["block_13", ["A four-step approach to solving this problem is outlined below.\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", [" TABLE 11.2 \n"]], ["block_16", [" Solvent \n Boiling Point (\u00b0C at 1 atm) \n K b (\u00baCm \u22121 ) \n Freezing Point (\u00b0C at 1 atm) \n K f (\u00baCm \u22121 ) \n"]], ["block_17", ["hydrogen acetate\n118.1\n3.07\n16.6\n3.9\n"]], ["block_18", ["benzene\n80.1\n2.53\n5.5\n5.12\n"]], ["block_19", ["chloroform\n61.26\n3.63\n\u221263.5\n4.68\n"]], ["block_20", ["nitrobenzene\n210.9\n5.24\n5.67\n8.1\n"]], ["block_21", ["Step 1. Calculate the change in boiling point.\n"]], ["block_22", ["Step 2. Add the boiling point elevation to the pure solvent\u2019s boiling point.\n"]], ["block_23", ["EXAMPLE 11.7\n"]], ["block_24", ["EXAMPLE 11.8\n"]]], "page_586": [["block_0", ["where m is the molal concentration of the solute and Kf is called the freezing point depression constant (or\ncryoscopic constant). Just as for boiling point elevation constants, these are characteristic properties whose\n"]], ["block_1", [{"image_0": "586_0.png", "coords": [72, 57, 432, 121]}]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["What is the boiling point of a solution of 1.0 g of glycerin, C3H5(OH)3, in 47.8 g of water? Assume an ideal\nsolution.\n"]], ["block_4", [" Answer: \n100.12 \u00b0C\n"]], ["block_5", [" Freezing Point Depression \n"]], ["block_6", ["Solutions freeze at lower temperatures than pure liquids. This phenomenon is exploited in \u201cde-icing\u201d schemes\nthat use salt (Figure 11.21), calcium chloride, or urea to melt ice on roads and sidewalks, and in the use of\nethylene glycol as an \u201cantifreeze\u201d in automobile radiators. Seawater freezes at a lower temperature than fresh\nwater, and so the Arctic and Antarctic oceans remain unfrozen even at temperatures below 0 \u00b0C (as do the body\nfluids of fish and other cold-blooded sea animals that live in these oceans).\n"]], ["block_7", [" FIGURE 11.21 \nRock salt (NaCl), calcium chloride (CaCl2), or a mixture of the two are used to melt ice. (credit:\n"]], ["block_8", ["modification of work by Eddie Welker)\n"]], ["block_9", ["The decrease in freezing point of a dilute solution compared to that of the pure solvent, \u0394Tf, is called the\n freezing point depression and is directly proportional to the molal concentration of the solute\n"]], ["block_10", ["Step 1. Convert from grams to moles of I2 using the molar mass of I2 in the unit conversion factor.\nResult: 0.363 mol\nStep 2. Determine the molality of the solution from the number of moles of solute and the mass of solvent,\nin kilograms.\nResult: 0.454 m\nStep 3. Use the direct proportionality between the change in boiling point and molal concentration to\ndetermine how much the boiling point changes.\nResult: 1.65 \u00b0C\nStep 4. Determine the new boiling point from the boiling point of the pure solvent and the change.\nResult: 62.91 \u00b0C\nCheck each result as a self-assessment.\n"]], ["block_11", [{"image_1": "586_1.png", "coords": [130, 453, 481, 624]}]], ["block_12", [" 11.4 \u2022 Colligative Properties \n 573 \n"]]], "page_587": [["block_0", [" 574 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", ["values depend on the chemical identity of the solvent. Values of Kf for several solvents are listed in Table 11.2.\n"]], ["block_2", [" Calculation of the Freezing Point of a Solution \n"]], ["block_3", ["Assuming ideal solution behavior, what is the freezing point of the 0.33 m solution of a nonvolatile\nnonelectrolyte solute in benzene described in Example 11.4?\n"]], ["block_4", [" Solution \n"]], ["block_5", ["Use the equation relating freezing point depression to solute molality to solve this problem in two steps.\n"]], ["block_6", [{"image_0": "587_0.png", "coords": [72, 190, 423, 253]}]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["Assuming ideal solution behavior, what is the freezing point of a 1.85 m solution of a nonvolatile nonelectrolyte\nsolute in nitrobenzene?\n"]], ["block_9", [" Answer: \n\u22129.3 \u00b0C\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["Chemistry in Everyday Life\n"]], ["block_12", [" Colligative Properties and De-Icing \nSodium chloride and its group 2 analogs calcium and magnesium chloride are often used to de-ice\nroadways and sidewalks, due to the fact that a solution of any one of these salts will have a freezing point\nlower than 0 \u00b0C, the freezing point of pure water. The group 2 metal salts are frequently mixed with the\ncheaper and more readily available sodium chloride (\u201crock salt\u201d) for use on roads, since they tend to be\nsomewhat less corrosive than the NaCl, and they provide a larger depression of the freezing point, since\nthey dissociate to yield three particles per formula unit, rather than two particles like the sodium chloride.\n"]], ["block_13", ["Because these ionic compounds tend to hasten the corrosion of metal, they would not be a wise choice to\nuse in antifreeze for the radiator in your car or to de-ice a plane prior to takeoff. For these applications,\ncovalent compounds, such as ethylene or propylene glycol, are often used. The glycols used in radiator\nfluid not only lower the freezing point of the liquid, but they elevate the boiling point, making the fluid\nuseful in both winter and summer. Heated glycols are often sprayed onto the surface of airplanes prior to\ntakeoff in inclement weather in the winter to remove ice that has already formed and prevent the formation\nof more ice, which would be particularly dangerous if formed on the control surfaces of the aircraft (Figure\n11.22).\n"]], ["block_14", ["Step 1. Calculate the change in freezing point.\n"]], ["block_15", ["Step 2. Subtract the freezing point change observed from the pure solvent\u2019s freezing point.\n"]], ["block_16", ["EXAMPLE 11.9\n"]]], "page_588": [["block_0", [" Phase Diagram for a Solution \n"]], ["block_1", ["The colligative effects on vapor pressure, boiling point, and freezing point described in the previous section\nare conveniently summarized by comparing the phase diagrams for a pure liquid and a solution derived from\nthat liquid (Figure 11.23).\n"]], ["block_2", [{"image_0": "588_0.png", "coords": [72, 307, 540, 590]}]], ["block_3", [" FIGURE 11.23 \nPhase diagrams for a pure solvent (solid curves) and a solution formed by dissolving nonvolatile\n"]], ["block_4", ["solute in the solvent (dashed curves).\n"]], ["block_5", ["The liquid-vapor curve for the solution is located beneath the corresponding curve for the solvent, depicting\nthe vapor pressure lowering, \u0394P, that results from the dissolution of nonvolatile solute. Consequently, at any\ngiven pressure, the solution\u2019s boiling point is observed at a higher temperature than that for the pure solvent,\nreflecting the boiling point elevation, \u0394Tb, associated with the presence of nonvolatile solute. The solid-liquid\ncurve for the solution is displaced left of that for the pure solvent, representing the freezing point depression,\n\u0394Tf, that accompanies solution formation. Finally, notice that the solid-gas curves for the solvent and its\nsolution are identical. This is the case for many solutions comprising liquid solvents and nonvolatile solutes.\nJust as for vaporization, when a solution of this sort is frozen, it is actually just the solvent molecules that\n"]], ["block_6", [" FIGURE 11.22 \nFreezing point depression is exploited to remove ice from (a) roadways and (b) the control\n"]], ["block_7", ["surfaces of aircraft.\n"]], ["block_8", [{"image_1": "588_1.png", "coords": [130, 57, 481, 189]}]], ["block_9", [" 11.4 \u2022 Colligative Properties \n 575 \n"]]], "page_589": [["block_0", [" 576 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", ["undergo the liquid-to-solid transition, forming pure solid solvent that excludes solute species. The solid and\ngaseous phases, therefore, are composed of solvent only, and so transitions between these phases are not\nsubject to colligative effects.\n"]], ["block_2", [" Osmosis and Osmotic Pressure of Solutions \n"]], ["block_3", ["A number of natural and synthetic materials exhibit selective permeation, meaning that only molecules or ions\nof a certain size, shape, polarity, charge, and so forth, are capable of passing through (permeating) the\nmaterial. Biological cell membranes provide elegant examples of selective permeation in nature, while dialysis\ntubing used to remove metabolic wastes from blood is a more simplistic technological example. Regardless of\nhow they may be fabricated, these materials are generally referred to as semipermeable membranes .\n"]], ["block_4", ["Consider the apparatus illustrated in Figure 11.24, in which samples of pure solvent and a solution are\nseparated by a membrane that only solvent molecules may permeate. Solvent molecules will diffuse across the\nmembrane in both directions. Since the concentration of solvent is greater in the pure solvent than the\nsolution, these molecules will diffuse from the solvent side of the membrane to the solution side at a faster rate\nthan they will in the reverse direction. The result is a net transfer of solvent molecules from the pure solvent to\nthe solution. Diffusion-driven transfer of solvent molecules through a semipermeable membrane is a process\nknown as osmosis .\n"]], ["block_5", [{"image_0": "589_0.png", "coords": [72, 285, 540, 575]}]], ["block_6", [" FIGURE 11.24 \n(a) A solution and pure solvent are initially separated by an osmotic membrane. (b) Net transfer of\n"]], ["block_7", ["solvent molecules to the solution occurs until its osmotic pressure yields equal rates of transfer in both directions.\n"]], ["block_8", ["When osmosis is carried out in an apparatus like that shown in Figure 11.24, the volume of the solution\nincreases as it becomes diluted by accumulation of solvent. This causes the level of the solution to rise,\nincreasing its hydrostatic pressure (due to the weight of the column of solution in the tube) and resulting in a\nfaster transfer of solvent molecules back to the pure solvent side. When the pressure reaches a value that\nyields a reverse solvent transfer rate equal to the osmosis rate, bulk transfer of solvent ceases. This pressure is\ncalled the osmotic pressure ( \u03a0 ) of the solution. The osmotic pressure of a dilute solution is related to its\nsolute molarity, M, and absolute temperature, T, according to the equation\n"]], ["block_9", ["where R is the universal gas constant.\n"]], ["block_10", [" Access for free at openstax.org \n"]]], "page_590": [["block_0", [" Calculation of Osmotic Pressure \n"]], ["block_1", ["Assuming ideal solution behavior, what is the osmotic pressure (atm) of a 0.30 M solution of glucose in water\nthat is used for intravenous infusion at body temperature, 37 \u00b0C?\n"]], ["block_2", [" Solution \n"]], ["block_3", ["Find the osmotic pressure, \u03a0, using the formula \u03a0 = MRT, where T is on the Kelvin scale (310 K) and the value\nof R is expressed in appropriate units (0.08206 L atm/mol K).\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["Assuming ideal solution behavior, what is the osmotic pressure (atm) a solution with a volume of 0.750 L that\ncontains 5.0 g of methanol, CH3OH, in water at 37 \u00b0C?\n"]], ["block_6", [" Answer: \n5.3 atm\n"]], ["block_7", ["If a solution is placed in an apparatus like the one shown in Figure 11.25, applying pressure greater than the\nosmotic pressure of the solution reverses the osmosis and pushes solvent molecules from the solution into the\npure solvent. This technique of reverse osmosis is used for large-scale desalination of seawater and on smaller\nscales to produce high-purity tap water for drinking.\n"]], ["block_8", [" FIGURE 11.25 \nApplying a pressure greater than the osmotic pressure of a solution will reverse osmosis. Solvent\n"]], ["block_9", ["molecules from the solution are pushed into the pure solvent.\n"]], ["block_10", ["EXAMPLE 11.10\n"]], ["block_11", [{"image_0": "590_0.png", "coords": [189, 398, 423, 704]}]], ["block_12", [" 11.4 \u2022 Colligative Properties \n 577 \n"]]], "page_591": [["block_0", [" 578 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", ["Examples of osmosis are evident in many biological systems because cells are surrounded by semipermeable\nmembranes. Carrots and celery that have become limp because they have lost water can be made crisp again\nby placing them in water. Water moves into the carrot or celery cells by osmosis. A cucumber placed in a\nconcentrated salt solution loses water by osmosis and absorbs some salt to become a pickle. Osmosis can also\naffect animal cells. Solute concentrations are particularly important when solutions are injected into the body.\nSolutes in body cell fluids and blood serum give these solutions an osmotic pressure of approximately 7.7 atm.\nSolutions injected into the body must have the same osmotic pressure as blood serum; that is, they should be\n isotonic with blood serum. If a less concentrated solution, a hypotonic solution, is injected in sufficient\nquantity to dilute the blood serum, water from the diluted serum passes into the blood cells by osmosis,\ncausing the cells to expand and rupture. This process is called hemolysis . When a more concentrated solution,\na hypertonic solution, is injected, the cells lose water to the more concentrated solution, shrivel, and possibly\ndie in a process called crenation . These effects are illustrated in Figure 11.27.\n"]], ["block_2", [" Access for free at openstax.org \n"]], ["block_3", ["Chemistry in Everyday Life\n"]], ["block_4", [" Reverse Osmosis Water Purification \nIn the process of osmosis, diffusion serves to move water through a semipermeable membrane from a less\nconcentrated solution to a more concentrated solution. Osmotic pressure is the amount of pressure that\nmust be applied to the more concentrated solution to cause osmosis to stop. If greater pressure is applied,\nthe water will go from the more concentrated solution to a less concentrated (more pure) solution. This is\ncalled reverse osmosis. Reverse osmosis (RO) is used to purify water in many applications, from\ndesalination plants in coastal cities, to water-purifying machines in grocery stores (Figure 11.26), and\nsmaller reverse-osmosis household units. With a hand-operated pump, small RO units can be used in\nthird-world countries, disaster areas, and in lifeboats. Our military forces have a variety of generator-\noperated RO units that can be transported in vehicles to remote locations.\n"]], ["block_5", [" FIGURE 11.26 \nReverse osmosis systems for purifying drinking water are shown here on (a) small and (b) large\n"]], ["block_6", ["scales. (credit a: modification of work by Jerry Kirkhart; credit b: modification of work by Willard J. Lathrop)\n"]], ["block_7", [{"image_0": "591_0.png", "coords": [90, 218, 522, 369]}]]], "page_592": [["block_0", [{"image_0": "592_0.png", "coords": [72, 57, 540, 287]}]], ["block_1", [" FIGURE 11.27 \nRed blood cell membranes are water permeable and will (a) swell and possibly rupture in a\n"]], ["block_2", ["hypotonic solution; (b) maintain normal volume and shape in an isotonic solution; and (c) shrivel and possibly die in\na hypertonic solution. (credit a/b/c: modifications of work by \u201cLadyofHats\u201d/Wikimedia commons)\n"]], ["block_3", [" Determination of Molar Masses \n"]], ["block_4", ["Osmotic pressure and changes in freezing point, boiling point, and vapor pressure are directly proportional to\nthe number of solute species present in a given amount of solution. Consequently, measuring one of these\nproperties for a solution prepared using a known mass of solute permits determination of the solute\u2019s molar\nmass.\n"]], ["block_5", [" Determination of a Molar Mass from a Freezing Point Depression \n"]], ["block_6", ["A solution of 4.00 g of a nonelectrolyte dissolved in 55.0 g of benzene is found to freeze at 2.32 \u00b0C. Assuming\nideal solution behavior, what is the molar mass of this compound?\n"]], ["block_7", [" Solution \n"]], ["block_8", ["Solve this problem using the following steps.\n"]], ["block_9", [{"image_1": "592_1.png", "coords": [72, 525, 432, 671]}]], ["block_10", ["Step 1. Determine the change in freezing point from the observed freezing point and the freezing point of\npure benzene (Table 11.2).\n"]], ["block_11", ["EXAMPLE 11.11\n"]], ["block_12", [" 11.4 \u2022 Colligative Properties \n 579 \n"]]], "page_593": [["block_0", [" 580 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["A solution of 35.7 g of a nonelectrolyte in 220.0 g of chloroform has a boiling point of 64.5 \u00b0C. Assuming ideal\nsolution behavior, what is the molar mass of this compound?\n"]], ["block_3", [" Answer: \n1.8\n10g/mol\n"]], ["block_4", [" Determination of a Molar Mass from Osmotic Pressure \n"]], ["block_5", ["A 0.500 L sample of an aqueous solution containing 10.0 g of hemoglobin has an osmotic pressure of 5.9 torr at\n22 \u00b0C. Assuming ideal solution behavior, what is the molar mass of hemoglobin?\n"]], ["block_6", [" Solution \n"]], ["block_7", ["Here is one set of steps that can be used to solve the problem:\n"]], ["block_8", [{"image_0": "593_0.png", "coords": [72, 446, 432, 510]}]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["Step 3. Determine the number of moles of compound in the solution from the molal concentration and the\nmass of solvent used to make the solution.\n"]], ["block_11", ["Step 1. Convert the osmotic pressure to atmospheres, then determine the molar concentration from the\nosmotic pressure.\n"]], ["block_12", ["Step 2. Determine the number of moles of hemoglobin in the solution from the concentration and the\nvolume of the solution.\n"]], ["block_13", ["Step 2. Determine the molal concentration from Kf, the freezing point depression constant for benzene\n(Table 11.2), and \u0394Tf.\n"]], ["block_14", ["Step 4. Determine the molar mass from the mass of the solute and the number of moles in that mass.\n"]], ["block_15", ["Step 3. Determine the molar mass from the mass of hemoglobin and the number of moles in that mass.\n"]], ["block_16", ["EXAMPLE 11.12\n"]]], "page_594": [["block_0", ["As noted previously in this module, the colligative properties of a solution depend only on the number, not on\nthe identity, of solute species dissolved. The concentration terms in the equations for various colligative\nproperties (freezing point depression, boiling point elevation, osmotic pressure) pertain to all solute species\npresent in the solution. For the solutions considered thus far in this chapter, the solutes have been\nnonelectrolytes that dissolve physically without dissociation or any other accompanying process. Each\nmolecule that dissolves yields one dissolved solute molecule. The dissolution of an electroyte, however, is not\nthis simple, as illustrated by the two common examples below:\n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["Assuming ideal solution behavior, what is the molar mass of a protein if a solution of 0.02 g of the protein in\n25.0 mL of solution has an osmotic pressure of 0.56 torr at 25 \u00b0C?\n"]], ["block_3", [" Answer: \n3\n10g/mol\n"]], ["block_4", [" Colligative Properties of Electrolytes \n"]], ["block_5", ["Considering the first of these examples, and assuming complete dissociation, a 1.0 m aqueous solution of NaCl\ncontains 2.0 mole of ions (1.0 mol Naand 1.0 mol Cl) per each kilogram of water, and its freezing point\ndepression is expected to be\n"]], ["block_6", ["When this solution is actually prepared and its freezing point depression measured, however, a value of 3.4 \u00b0C\nis obtained. Similar discrepancies are observed for other ionic compounds, and the differences between the\nmeasured and expected colligative property values typically become more significant as solute concentrations\nincrease. These observations suggest that the ions of sodium chloride (and other strong electrolytes) are not\ncompletely dissociated in solution.\n"]], ["block_7", ["To account for this and avoid the errors accompanying the assumption of total dissociation, an experimentally\nmeasured parameter named in honor of Nobel Prize-winning German chemist Jacobus Henricus van\u2019t Hoff is\nused. The van\u2019t Hoff factor (i) is defined as the ratio of solute particles in solution to the number of formula\nunits dissolved:\n"]], ["block_8", ["Values for measured van\u2019t Hoff factors for several solutes, along with predicted values assuming complete\ndissociation, are shown in Table 11.3.\n"]], ["block_9", [" TABLE 11.3 \n"]], ["block_10", ["C12H22O11 (glucose)\nNonelectrolyte\nC12H22O11\n1\n1.0\n"]], ["block_11", [" Formula unit \n Classification \n Dissolution products \n i (predicted) \n i (measured) \n"]], ["block_12", ["MgSO4\nStrong electrolyte\nMg, SO4,\n2\n1.3\n"]], ["block_13", ["NaCl\nStrong electrolyte\nNa, Cl\n2\n1.9\n"]], ["block_14", ["HCl\nStrong electrolyte (acid)\nH3O, Cl\n2\n1.9\n"]], ["block_15", ["Predicated and Measured van\u2019t Hoff Factors for Several 0.050 m Aqueous Solutions\n"]], ["block_16", [" 11.4 \u2022 Colligative Properties \n 581 \n"]]], "page_595": [["block_0", [" 582 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", ["In 1923, the chemists Peter Debye and Erich H\u00fcckel proposed a theory to explain the apparent incomplete\nionization of strong electrolytes. They suggested that although interionic attraction in an aqueous solution is\nvery greatly reduced by solvation of the ions and the insulating action of the polar solvent, it is not completely\nnullified. The residual attractions prevent the ions from behaving as totally independent particles (Figure\n11.28). In some cases, a positive and negative ion may actually touch, giving a solvated unit called an ion pair.\nThus, the activity , or the effective concentration, of any particular kind of ion is less than that indicated by the\nactual concentration. Ions become more and more widely separated the more dilute the solution, and the\nresidual interionic attractions become less and less. Thus, in extremely dilute solutions, the effective\nconcentrations of the ions (their activities) are essentially equal to the actual concentrations. Note that the\nvan\u2019t Hoff factors for the electrolytes in Table 11.3 are for 0.05 m solutions, at which concentration the value of\ni for NaCl is 1.9, as opposed to an ideal value of 2.\n"]], ["block_2", [" The Freezing Point of a Solution of an Electrolyte \n"]], ["block_3", ["The concentration of ions in seawater is approximately the same as that in a solution containing 4.2 g of NaCl\ndissolved in 125 g of water. Use this information and a predicted value for the van\u2019t Hoff factor (Table 11.3) to\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", [" FIGURE 11.28 \nDissociation of ionic compounds in water is not always complete due to the formation of ion pairs.\n"]], ["block_6", [" TABLE 11.3 \n"]], ["block_7", ["EXAMPLE 11.13\n"]], ["block_8", [" Formula unit \n Classification \n Dissolution products \n i (predicted) \n i (measured) \n"]], ["block_9", ["MgCl2\nStrong electrolyte\nMg, 2Cl\n3\n2.7\n"]], ["block_10", ["FeCl3\nStrong electrolyte\nFe, 3Cl\n4\n3.4\n"]], ["block_11", [{"image_0": "595_0.png", "coords": [130, 313, 481, 623]}]]], "page_596": [["block_0", ["determine the freezing temperature the solution (assume ideal solution behavior).\n"]], ["block_1", [" Solution \n"]], ["block_2", ["Solve this problem using the following series of steps.\n"]], ["block_3", [{"image_0": "596_0.png", "coords": [72, 110, 432, 243]}]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["Assuming complete dissociation and ideal solution behavior, calculate the freezing point of a solution of 0.724\ng of CaCl2 in 175 g of water.\n"]], ["block_6", [" Answer: \n\u22120.208 \u00b0C\n"]], ["block_7", [" 11.5 Colloids \n"]], ["block_8", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_9", ["As a child, you may have made suspensions such as mixtures of mud and water, flour and water, or a\nsuspension of solid pigments in water, known as tempera paint. These suspensions are heterogeneous\nmixtures composed of relatively large particles that are visible (or that can be seen with a magnifying glass).\nThey are cloudy, and the suspended particles settle out after mixing. On the other hand, a solution is a\nhomogeneous mixture in which no settling occurs and in which the dissolved species are molecules or ions.\nSolutions exhibit completely different behavior from suspensions. A solution may be colored, but it is\ntransparent, the molecules or ions are invisible, and they do not settle out on standing. Another class of\nmixtures called colloids (or colloidal dispersions ) exhibit properties intermediate between those of\nsuspensions and solutions (Figure 11.29). The particles in a colloid are larger than most simple molecules;\n"]], ["block_10", ["\u2022\nDescribe the composition and properties of colloidal dispersions\n"]], ["block_11", ["\u2022\nList and explain several technological applications of colloids\n"]], ["block_12", ["Step 1. Convert from grams to moles of NaCl using the molar mass of NaCl in the unit conversion factor.\nResult: 0.072 mol NaCl\nStep 2. Determine the number of moles of ions present in the solution using the number of moles of ions\nin 1 mole of NaCl as the conversion factor (2 mol ions/1 mol NaCl).\nResult: 0.14 mol ions\nStep 3. Determine the molality of the ions in the solution from the number of moles of ions and the mass of\nsolvent, in kilograms.\nResult: 1.2 m\nStep 4. Use the direct proportionality between the change in freezing point and molal concentration to\ndetermine how much the freezing point changes.\nResult: 2.1 \u00b0C\nStep 5. Determine the new freezing point from the freezing point of the pure solvent and the change.\nResult: \u22122.1 \u00b0C\nCheck each result as a self-assessment, taking care to avoid rounding errors by retaining guard digits in\neach step\u2019s result for computing the next step\u2019s result.\n"]], ["block_13", [" 11.5 \u2022 Colloids \n 583 \n"]]], "page_597": [["block_0", [" 584 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", ["however, colloidal particles are small enough that they do not settle out upon standing.\n"]], ["block_2", [{"image_0": "597_0.png", "coords": [72, 76, 540, 364]}]], ["block_3", [" FIGURE 11.29 \n(a) A solution is a homogeneous mixture that appears clear, such as the saltwater in this aquarium.\n"]], ["block_4", ["(b) In a colloid, such as milk, the particles are much larger but remain dispersed and do not settle. (c) A suspension,\nsuch as mud, is a heterogeneous mixture of suspended particles that appears cloudy and in which the particles can\nsettle. (credit a photo: modification of work by Adam Wimsatt; credit b photo: modification of work by Melissa\nWiese; credit c photo: modification of work by Peter Burgess)\n"]], ["block_5", ["The particles in a colloid are large enough to scatter light, a phenomenon called the Tyndall effect . This can\nmake colloidal mixtures appear cloudy or opaque, such as the searchlight beams shown in Figure 11.30.\nClouds are colloidal mixtures. They are composed of water droplets that are much larger than molecules, but\nthat are small enough that they do not settle out.\n"]], ["block_6", [" Access for free at openstax.org \n"]]], "page_598": [["block_0", [" FIGURE 11.30 \nThe paths of searchlight beams are made visible when light is scattered by colloidal-size particles\n"]], ["block_1", ["in the air (fog, smoke, etc.). (credit: \u201cBahman\u201d/Wikimedia Commons)\n"]], ["block_2", ["The term \u201ccolloid\u201d\u2014from the Greek words kolla, meaning \u201cglue,\u201d and eidos, meaning \u201clike\u201d\u2014was first used in\n1861 by Thomas Graham to classify mixtures such as starch in water and gelatin. Many colloidal particles are\naggregates of hundreds or thousands of molecules, but others (such as proteins and polymer molecules)\nconsist of a single extremely large molecule. The protein and synthetic polymer molecules that form colloids\nmay have molecular masses ranging from a few thousand to many million atomic mass units.\n"]], ["block_3", ["Analogous to the identification of solution components as \u201csolute\u201d and \u201csolvent,\u201d the components of a colloid\nare likewise classified according to their relative amounts. The particulate component typically present in a\nrelatively minor amount is called the dispersed phase and the substance or solution throughout which the\nparticulate is dispersed is called the dispersion medium . Colloids may involve virtually any combination of\nphysical states (gas in liquid, liquid in solid, solid in gas, etc.), as illustrated by the examples of colloidal\nsystems given in Table 11.4.\n"]], ["block_4", [" TABLE 11.4 \n"]], ["block_5", [" Dispersed Phase \n Dispersion Medium \n Common Examples \n Name \n"]], ["block_6", ["solid\ngas\nsmoke, dust\n\u2014\n"]], ["block_7", ["solid\nliquid\nstarch in water, some inks, paints, milk of magnesia\nsol\n"]], ["block_8", ["solid\nsolid\nsome colored gems, some alloys\n\u2014\n"]], ["block_9", ["liquid\ngas\nclouds, fogs, mists, sprays\naerosol\n"]], ["block_10", ["liquid\nliquid\nmilk, mayonnaise, butter\nemulsion\n"]], ["block_11", ["liquid\nsolid\njellies, gels, pearl, opal (H2O in SiO2)\ngel\n"]], ["block_12", [{"image_0": "598_0.png", "coords": [130, 57, 481, 323]}]], ["block_13", ["Examples of Colloidal Systems\n"]], ["block_14", [" 11.5 \u2022 Colloids \n 585 \n"]]], "page_599": [["block_0", [" 586 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", [" Preparation of Colloidal Systems \n"]], ["block_2", ["Colloids are prepared by producing particles of colloidal dimensions and distributing these particles\nthroughout a dispersion medium. Particles of colloidal size are formed by two methods:\n"]], ["block_3", ["A few solid substances, when brought into contact with water, disperse spontaneously and form colloidal\nsystems. Gelatin, glue, starch, and dehydrated milk powder behave in this manner. The particles are already of\ncolloidal size; the water simply disperses them. Powdered milk particles of colloidal size are produced by\ndehydrating milk spray. Some atomizers produce colloidal dispersions of a liquid in air.\n"]], ["block_4", ["An emulsion may be prepared by shaking together or blending two immiscible liquids. This breaks one liquid\ninto droplets of colloidal size, which then disperse throughout the other liquid. Oil spills in the ocean may be\ndifficult to clean up, partly because wave action can cause the oil and water to form an emulsion. In many\nemulsions, however, the dispersed phase tends to coalesce, form large drops, and separate. Therefore,\nemulsions are usually stabilized by an emulsifying agent , a substance that inhibits the coalescence of the\ndispersed liquid. For example, a little soap will stabilize an emulsion of kerosene in water. Milk is an emulsion\nof butterfat in water, with the protein casein serving as the emulsifying agent. Mayonnaise is an emulsion of oil\nin vinegar, with egg yolk components as the emulsifying agents.\n"]], ["block_5", ["Condensation methods form colloidal particles by aggregation of molecules or ions. If the particles grow\nbeyond the colloidal size range, drops or precipitates form, and no colloidal system results. Clouds form when\nwater molecules aggregate and form colloid-sized particles. If these water particles coalesce to form\nadequately large water drops of liquid water or crystals of solid water, they settle from the sky as rain, sleet, or\nsnow. Many condensation methods involve chemical reactions. A red colloidal suspension of iron(III)\nhydroxide may be prepared by mixing a concentrated solution of iron(III) chloride with hot water:\n"]], ["block_6", ["A colloidal gold sol results from the reduction of a very dilute solution of gold(III) chloride by a reducing agent\nsuch as formaldehyde, tin(II) chloride, or iron(II) sulfate:\n"]], ["block_7", ["Some gold sols prepared in 1857 are still intact (the particles have not coalesced and settled), illustrating the\nlong-term stability of many colloids.\n"]], ["block_8", [" Soaps and Detergents \n"]], ["block_9", ["Pioneers made soap by boiling fats with a strongly basic solution made by leaching potassium carbonate,\nK2CO3, from wood ashes with hot water. Animal fats contain polyesters of fatty acids (long-chain carboxylic\nacids). When animal fats are treated with a base like potassium carbonate or sodium hydroxide, glycerol and\nsalts of fatty acids such as palmitic, oleic, and stearic acid are formed. The salts of fatty acids are called soaps.\nThe sodium salt of stearic acid, sodium stearate, has the formula C17H35CO2Na and contains an uncharged\nnonpolar hydrocarbon chain, the C17H35\u2014 unit, and an ionic carboxylate group, the \u2014\nunit (Figure\n"]], ["block_10", ["11.31).\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["1.\nDispersion methods: breaking down larger particles. For example, paint pigments are produced by\ndispersing large particles by grinding in special mills.\n"]], ["block_13", ["2.\nCondensation methods: growth from smaller units, such as molecules or ions. For example, clouds form\nwhen water molecules condense and form very small droplets.\n"]], ["block_14", [" TABLE 11.4 \n"]], ["block_15", [" Dispersed Phase \n Dispersion Medium \n Common Examples \n Name \n"]], ["block_16", ["gas\nliquid\nfoams, whipped cream, beaten egg whites\nfoam\n"]], ["block_17", ["gas\nsolid\npumice, floating soaps\n\u2014\n"]]], "page_600": [["block_0", ["Detergents (soap substitutes) also contain nonpolar hydrocarbon chains, such as C12H25\u2014, and an ionic group,\nsuch as a sulfate\u2014\nor a sulfonate\u2014\n(Figure 11.32). Soaps form insoluble calcium and magnesium\n"]], ["block_1", [{"image_0": "600_0.png", "coords": [72, 57, 540, 114]}]], ["block_2", [" FIGURE 11.31 \nSoaps contain a nonpolar hydrocarbon end (blue) and an ionic end (red). The ionic end is a\n"]], ["block_3", ["carboxylate group. The length of the hydrocarbon end can vary from soap to soap.\n"]], ["block_4", ["compounds in hard water; detergents form water-soluble products\u2014a definite advantage for detergents.\n"]], ["block_5", [{"image_1": "600_1.png", "coords": [72, 192, 540, 236]}]], ["block_6", [" FIGURE 11.32 \nDetergents contain a nonpolar hydrocarbon end (blue) and an ionic end (red). The ionic end can be\n"]], ["block_7", ["either a sulfate or a sulfonate. The length of the hydrocarbon end can vary from detergent to detergent.\n"]], ["block_8", ["The cleaning action of soaps and detergents can be explained in terms of the structures of the molecules\ninvolved. The hydrocarbon (nonpolar) end of a soap or detergent molecule dissolves in, or is attracted to,\nnonpolar substances such as oil, grease, or dirt particles. The ionic end is attracted by water (polar), illustrated\nin Figure 11.33. As a result, the soap or detergent molecules become oriented at the interface between the dirt\nparticles and the water so they act as a kind of bridge between two different kinds of matter, nonpolar and\npolar. Molecules such as this are termed amphiphilic since they have both a hydrophobic (\u201cwater-fearing\u201d)\npart and a hydrophilic (\u201cwater-loving\u201d) part. As a consequence, dirt particles become suspended as colloidal\nparticles and are readily washed away.\n"]], ["block_9", [" FIGURE 11.33 \nThis diagrammatic cross section of an emulsified drop of oil in water shows how soap or detergent\n"]], ["block_10", ["acts as an emulsifier.\n"]], ["block_11", ["Chemistry in Everyday Life\n"]], ["block_12", [" Deepwater Horizon Oil Spill \nThe blowout of the Deepwater Horizon oil drilling rig on April 20, 2010, in the Gulf of Mexico near\nMississippi began the largest marine oil spill in the history of the petroleum industry. In the 87 days\nfollowing the blowout, an estimated 4.9 million barrels (210 million gallons) of oil flowed from the ruptured\nwell 5000 feet below the water\u2019s surface. The well was finally declared sealed on September 19, 2010.\n"]], ["block_13", ["Crude oil is immiscible with and less dense than water, so the spilled oil rose to the surface of the water.\n"]], ["block_14", [{"image_2": "600_2.png", "coords": [189, 377, 423, 573]}]], ["block_15", [" 11.5 \u2022 Colloids \n 587 \n"]]], "page_601": [["block_0", [" 588 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", [" Electrical Properties of Colloidal Particles \n"]], ["block_2", ["Dispersed colloidal particles are often electrically charged. A colloidal particle of iron(III) hydroxide, for\nexample, does not contain enough hydroxide ions to compensate exactly for the positive charges on the\niron(III) ions. Thus, each individual colloidal particle bears a positive charge, and the colloidal dispersion\nconsists of charged colloidal particles and some free hydroxide ions, which keep the dispersion electrically\nneutral. Most metal hydroxide colloids have positive charges, whereas most metals and metal sulfides form\nnegatively charged dispersions. All colloidal particles in any one system have charges of the same sign. This\nhelps keep them dispersed because particles containing like charges repel each other.\n"]], ["block_3", ["The charged nature of some colloidal particles may be exploited to remove them from a variety of mixtures.\nFor example, the particles comprising smoke are often colloidally dispersed and electrically charged.\nFrederick Cottrell, an American chemist, developed a process to remove these particles. The charged particles\nare attracted to highly charged electrodes, where they are neutralized and deposited as dust (Figure 11.36).\nThis is one of the important methods used to clean up the smoke from a variety of industrial processes. The\nprocess is also important in the recovery of valuable products from the smoke and flue dust of smelters,\nfurnaces, and kilns. There are also similar electrostatic air filters designed for home use to improve indoor air\nquality.\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", ["Floating booms, skimmer ships, and controlled burns were used to remove oil from the water\u2019s surface in\nan attempt to protect beaches and wetlands along the Gulf coast. In addition to removal of the oil, attempts\nwere also made to lessen its environmental impact by rendering it \u201csoluble\u201d (in the loose sense of the term)\nand thus allowing it to be diluted to hopefully less harmful levels by the vast volume of ocean water. This\napproach used 1.84 million gallons of the oil dispersant Corexit 9527, most of which was injected\nunderwater at the site of the leak, with small amounts being sprayed on top of the spill. Corexit 9527\ncontains 2-butoxyethanol (C6H14O2), an amphiphilic molecule whose polar and nonpolar ends are useful\nfor emulsifying oil into small droplets, increasing the surface area of the oil and making it more available to\nmarine bacteria for digestion (Figure 11.34). While this approach avoids many of the immediate hazards\nthat bulk oil poses to marine and coastal ecosystems, it introduces the possibility of long-term effects\nresulting from the introduction of the complex and potential toxic components of petroleum into the\nocean\u2019s food chain. A number of organizations are involved in monitoring the extended impact of this oil\nspill, including the National Oceanic and Atmospheric Administration (visit this website\n(http://openstax.org/l/16gulfspill) for additional details).\n"]], ["block_6", [" FIGURE 11.34 \n(a) This NASA satellite image shows the oil slick from the Deepwater Horizon spill. (b) A US Air\n"]], ["block_7", ["Force plane sprays Corexit, a dispersant. (c) The molecular structure of 2-butoxyethanol is shown. (credit a:\nmodification of work by \u201cNASA, FT2, demis.nl\u201d/Wikimedia Commons; credit b: modification of work by \u201cNASA/\nMODIS Rapid Response Team\u201d/Wikimedia Commons)\n"]], ["block_8", [{"image_0": "601_0.png", "coords": [90, 240, 522, 357]}]]], "page_602": [["block_0", ["Portrait of a Chemist\n"]], ["block_1", [" Frederick Gardner Cottrell \n"]], ["block_2", [" FIGURE 11.35 \n(a) Frederick Cottrell developed (b) the electrostatic precipitator, a device designed to curb air\n"]], ["block_3", ["pollution by removing colloidal particles from air. (credit b: modification of work by \u201cSpLot\u201d/Wikimedia\nCommons)\n"]], ["block_4", ["Born in Oakland, CA, in 1877, Frederick Cottrell devoured textbooks as if they were novels and graduated\nfrom high school at the age of 16. He then entered the University of California (UC), Berkeley, completing a\nBachelor\u2019s degree in three years. He saved money from his $1200 annual salary as a chemistry teacher at\nOakland High School to fund his studies in chemistry in Berlin with Nobel prize winner Jacobus Henricus\nvan\u2019t Hoff, and in Leipzig with Wilhelm Ostwald, another Nobel awardee. After earning his PhD in physical\nchemistry, he returned to the United States to teach at UC Berkeley. He also consulted for the DuPont\nCompany, where he developed the electrostatic precipitator, a device designed to curb air pollution by\nremoving colloidal particles from air. Cottrell used the proceeds from his invention to fund a nonprofit\nresearch corporation to finance scientific research.\n"]], ["block_5", [{"image_0": "602_0.png", "coords": [196, 105, 415, 256]}]], ["block_6", [" 11.5 \u2022 Colloids \n 589 \n"]]], "page_603": [["block_0", [" 590 \n 11 \u2022 Solutions and Colloids \n"]], ["block_1", [" FIGURE 11.36 \nIn a Cottrell precipitator, positively and negatively charged particles are attracted to highly charged\n"]], ["block_2", ["electrodes, where they are neutralized and deposited as dust.\n"]], ["block_3", [" Gels \n"]], ["block_4", ["Gelatin desserts, such as Jell-O, are a type of colloid (Figure 11.37). Gelatin sets on cooling because the hot\naqueous mixture of gelatin coagulates as it cools, yielding an extremely viscous body known as a gel . A gel is a\ncolloidal dispersion of a liquid phase throughout a solid phase. It appears that the fibers of the dispersing\nmedium form a complex three-dimensional network, the interstices being filled with the liquid medium or a\ndilute solution of the dispersing medium.\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", [{"image_0": "603_0.png", "coords": [189, 57, 423, 361]}]]], "page_604": [["block_0", [{"image_0": "604_0.png", "coords": [72, 57, 540, 327]}]], ["block_1", [" FIGURE 11.37 \nGelatin desserts are colloids in which an aqueous solution of sweeteners and flavors is dispersed\n"]], ["block_2", ["throughout a medium of solid proteins. (credit photo: modification of work by Steven Depolo)\n"]], ["block_3", ["Pectin, a carbohydrate from fruit juices, is a gel-forming substance important in jelly making. Silica gel, a\ncolloidal dispersion of hydrated silicon dioxide, is formed when dilute hydrochloric acid is added to a dilute\nsolution of sodium silicate. Canned Heat is a flammable gel made by mixing alcohol and a saturated aqueous\nsolution of calcium acetate.\n"]], ["block_4", [" 11.5 \u2022 Colloids \n 591 \n"]]], "page_605": [["block_0", [" 592 \n 11 \u2022 Key Terms \n"]], ["block_1", [" Key Terms \n"]], ["block_2", [" alloy \nsolid mixture of a metallic element and one\n"]], ["block_3", [" amphiphilic \nmolecules possessing both\n"]], ["block_4", [" boiling point elevation \nelevation of the boiling\n"]], ["block_5", [" boiling point elevation constant \nthe\n"]], ["block_6", [" colligative property \nproperty of a solution that\n"]], ["block_7", [" colloid \n(also, colloid al dispersion) mixture in which\n"]], ["block_8", [" crenation \nprocess whereby biological cells become\n"]], ["block_9", [" dispersed phase \nsubstance present as relatively\n"]], ["block_10", [" dispersion medium \nsolid, liquid, or gas in which\n"]], ["block_11", [" dissociation \nphysical process accompanying the\n"]], ["block_12", [" electrolyte \nsubstance that produces ions when\n"]], ["block_13", [" emulsifying agent \namphiphilic substance used to\n"]], ["block_14", [" emulsion \ncolloid formed from immiscible liquids\n"]], ["block_15", [" freezing point depression \nlowering of the freezing\n"]], ["block_16", [" freezing point depression constant \n(also,\n"]], ["block_17", [" gel \ncolloidal dispersion of a liquid in a solid\n"]], ["block_18", [" hemolysis \nrupture of red blood cells due to the\n"]], ["block_19", [" Henry\u2019s law \nthe proportional relationship between\n"]], ["block_20", [" hypertonic \nof greater osmotic pressure\n"]], ["block_21", [" hypotonic \nof less osmotic pressure\n"]], ["block_22", [" ideal solution \nsolution that forms with no\n"]], ["block_23", [" immiscible \nof negligible mutual solubility;\n"]], ["block_24", [" Access for free at openstax.org \n"]], ["block_25", ["or more additional elements\n"]], ["block_26", ["hydrophobic (nonpolar) and a hydrophilic (polar)\nparts\n"]], ["block_27", ["point of a liquid by addition of a solute\n"]], ["block_28", ["proportionality constant in the equation relating\nboiling point elevation to solute molality; also\nknown as the ebullioscopic constant\n"]], ["block_29", ["depends only on the concentration of a solute\nspecies\n"]], ["block_30", ["relatively large solid or liquid particles are\ndispersed uniformly throughout a gas, liquid, or\nsolid\n"]], ["block_31", ["shriveled due to loss of water by osmosis\n"]], ["block_32", ["large solid or liquid particles in a colloid\n"]], ["block_33", ["colloidal particles are dispersed\n"]], ["block_34", ["dissolution of an ionic compound in which the\ncompound\u2019s constituent ions are solvated and\ndispersed throughout the solution\n"]], ["block_35", ["dissolved in water\n"]], ["block_36", ["stabilize the particles of some emulsions\n"]], ["block_37", ["point of a liquid by addition of a solute\n"]], ["block_38", ["cryoscopic constant) proportionality constant in\nthe equation relating freezing point depression to\nsolute molality\n"]], ["block_39", ["accumulation of excess water by osmosis\n"]], ["block_40", ["the concentration of dissolved gas in a solution\nand the partial pressure of the gas in contact with\nthe solution\n"]], ["block_41", ["accompanying energy change\n"]], ["block_42", ["typically refers to liquid substances\n"]], ["block_43", [" ion pair \nsolvated anion/cat ion pair held together\n"]], ["block_44", [" ion-dipole attraction \nelectrostatic attraction\n"]], ["block_45", [" isotonic \nof equal osmotic pressure\n"]], ["block_46", [" miscible \nmutually soluble in all proportions;\n"]], ["block_47", [" molality (m) \na concentration unit defined as the\n"]], ["block_48", [" nonelectrolyte \nsubstance that does not produce\n"]], ["block_49", [" osmosis \ndiffusion of solvent molecules through a\n"]], ["block_50", [" osmotic pressure ( \u03a0 ) \nopposing pressure required\n"]], ["block_51", [" partially miscible \nof moderate mutual solubility;\n"]], ["block_52", [" Raoult\u2019s law \nthe relationship between a solution\u2019s\n"]], ["block_53", [" saturated \nof concentration equal to solubility;\n"]], ["block_54", [" semipermeable membrane \na membrane that\n"]], ["block_55", [" solubility \nextent to which a solute may be\n"]], ["block_56", [" solvation \nexothermic process in which\n"]], ["block_57", [" spontaneous process \nphysical or chemical change\n"]], ["block_58", [" strong electrolyte \nsubstance that dissociates or\n"]], ["block_59", [" supersaturated \nof concentration that exceeds\n"]], ["block_60", [" suspension \nheterogeneous mixture in which\n"]], ["block_61", [" Tyndall effect \nscattering of visible light by a\n"]], ["block_62", [" unsaturated \nof concentration less than solubility\n"]], ["block_63", [" van\u2019t Hoff factor (i) \nthe ratio of the number of\n"]], ["block_64", [" weak electrolyte \nsubstance that ionizes only\n"]], ["block_65", ["by moderate electrostatic attraction\n"]], ["block_66", ["between an ion and a polar molecule\n"]], ["block_67", ["typically refers to liquid substances\n"]], ["block_68", ["ratio of the numbers of moles of solute to the\nmass of the solvent in kilograms\n"]], ["block_69", ["ions when dissolved in water\n"]], ["block_70", [" semipermeable membrane \n"]], ["block_71", ["to prevent bulk transfer of solvent molecules\nthrough a semipermeable membrane\n"]], ["block_72", ["typically refers to liquid substances\n"]], ["block_73", ["vapor pressure and the vapor pressures and\nconcentrations of its components\n"]], ["block_74", ["containing the maximum concentration of solute\npossible for a given temperature and pressure\n"]], ["block_75", ["selectively permits passage of certain ions or\nmolecules\n"]], ["block_76", ["dissolved in water, or any solvent\n"]], ["block_77", ["intermolecular attractive forces between the\nsolute and solvent in a solution are established\n"]], ["block_78", ["that occurs without the addition of energy from\nan external source\n"]], ["block_79", ["ionizes completely when dissolved in water\n"]], ["block_80", ["solubility; a nonequilibrium state\n"]], ["block_81", ["relatively large component particles are\ntemporarily dispersed but settle out over time\n"]], ["block_82", ["colloidal dispersion\n"]], ["block_83", ["moles of particles in a solution to the number of\nmoles of formula units dissolved in the solution\n"]], ["block_84", ["partially when dissolved in water\n"]]], "page_606": [["block_0", [" Key Equations \n"]], ["block_1", [" Summary \n"]], ["block_2", [" 11.1 The Dissolution Process \n"]], ["block_3", ["A solution forms when two or more substances\ncombine physically to yield a mixture that is\nhomogeneous at the molecular level. The solvent is\nthe most concentrated component and determines\nthe physical state of the solution. The solutes are the\nother components typically present at\nconcentrations less than that of the solvent.\nSolutions may form endothermically or\nexothermically, depending upon the relative\nmagnitudes of solute and solvent intermolecular\nattractive forces. Ideal solutions form with no\nappreciable change in energy.\n"]], ["block_4", [" 11.2 Electrolytes \n"]], ["block_5", ["Substances that dissolve in water to yield ions are\ncalled electrolytes. Electrolytes may be covalent\ncompounds that chemically react with water to\nproduce ions (for example, acids and bases), or they\nmay be ionic compounds that dissociate to yield\ntheir constituent cations and anions, when\ndissolved. Dissolution of an ionic compound is\nfacilitated by ion-dipole attractions between the ions\nof the compound and the polar water molecules.\nSoluble ionic substances and strong acids ionize\ncompletely and are strong electrolytes, while weak\nacids and bases ionize to only a small extent and are\nweak electrolytes. Nonelectrolytes are substances\nthat do not produce ions when dissolved in water.\n"]], ["block_6", [" 11.3 Solubility \n"]], ["block_7", ["The extent to which one substance will dissolve in\nanother is determined by several factors, including\nthe types and relative strengths of intermolecular\nattractive forces that may exist between the\nsubstances\u2019 atoms, ions, or molecules. This\ntendency to dissolve is quantified as a substance\u2019s\nsolubility, its maximum concentration in a solution\nat equilibrium under specified conditions. A\n"]], ["block_8", ["\u03a0 = MRT\n"]], ["block_9", ["\u0394Tb = Kbm\n"]], ["block_10", ["\u0394Tf = Kfm\n"]], ["block_11", ["saturated solution contains solute at a concentration\nequal to its solubility. A supersaturated solution is\none in which a solute\u2019s concentration exceeds its\nsolubility\u2014a nonequilibrium (unstable) condition\nthat will result in solute precipitation when the\nsolution is appropriately perturbed. Miscible liquids\nare soluble in all proportions, and immiscible\nliquids exhibit very low mutual solubility.\nSolubilities for gaseous solutes decrease with\nincreasing temperature, while those for most, but\nnot all, solid solutes increase with temperature. The\nconcentration of a gaseous solute in a solution is\nproportional to the partial pressure of the gas to\nwhich the solution is exposed, a relation known as\nHenry\u2019s law.\n"]], ["block_12", [" 11.4 Colligative Properties \n"]], ["block_13", ["Properties of a solution that depend only on the\nconcentration of solute particles are called\ncolligative properties. They include changes in the\nvapor pressure, boiling point, and freezing point of\nthe solvent in the solution. The magnitudes of these\nproperties depend only on the total concentration of\nsolute particles in solution, not on the type of\nparticles. The total concentration of solute particles\nin a solution also determines its osmotic pressure.\nThis is the pressure that must be applied to the\nsolution to prevent diffusion of molecules of pure\nsolvent through a semipermeable membrane into\nthe solution. Ionic compounds may not completely\ndissociate in solution due to activity effects, in which\ncase observed colligative effects may be less than\npredicted.\n"]], ["block_14", [" 11.5 Colloids \n"]], ["block_15", ["Colloids are mixtures in which one or more\nsubstances are dispersed as relatively large solid\nparticles or liquid droplets throughout a solid,\nliquid, or gaseous medium. The particles of a colloid\nremain dispersed and do not settle due to gravity,\n"]], ["block_16", [" 11 \u2022 Key Equations \n 593 \n"]]], "page_607": [["block_0", [" 594 \n 11 \u2022 Exercises \n"]], ["block_1", ["and they are often electrically charged. Colloids are\nwidespread in nature and are involved in many\n"]], ["block_2", [" Exercises \n"]], ["block_3", [" 11.1 The Dissolution Process \n"]], ["block_4", [" 11.2 Electrolytes \n"]], ["block_5", [" 10 . Explain why solutions of HBr in benzene (a nonpolar solvent) are nonconductive, while solutions in water\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [" 1 . How do solutions differ from compounds? From other mixtures?\n 2 . Which of the principal characteristics of solutions are evident in the solutions of K2Cr2O7 shown in Figure\n"]], ["block_8", [" 3 . When KNO3 is dissolved in water, the resulting solution is significantly colder than the water was\n"]], ["block_9", [" 4 . Give an example of each of the following types of solutions:\n"]], ["block_10", [" 5 . Indicate the most important types of intermolecular attractions in each of the following solutions:\n"]], ["block_11", [" 6 . Predict whether each of the following substances would be more soluble in water (polar solvent) or in a\n"]], ["block_12", [" 7 . Heat is released when some solutions form; heat is absorbed when other solutions form. Provide a\n"]], ["block_13", [" 8 . Solutions of hydrogen in palladium may be formed by exposing Pd metal to H2 gas. The concentration of\n"]], ["block_14", [" 9 . Explain why the ions Naand Clare strongly solvated in water but not in hexane, a solvent composed of\n"]], ["block_15", ["11.2?\n"]], ["block_16", ["originally.\n(a) Is the dissolution of KNO3 an endothermic or an exothermic process?\n(b) What conclusions can you draw about the intermolecular attractions involved in the process?\n(c) Is the resulting solution an ideal solution?\n"]], ["block_17", ["(a) a gas in a liquid\n(b) a gas in a gas\n(c) a solid in a solid\n"]], ["block_18", ["(a) The solution in Figure 11.2.\n(b) NO(l) in CO(l)\n(c) Cl2(g) in Br2(l)\n(d) HCl(g) in benzene C6H6(l)\n(e) Methanol CH3OH(l) in H2O(l)\n"]], ["block_19", ["hydrocarbon such as heptane (C7H16, nonpolar solvent):\n(a) vegetable oil (nonpolar)\n(b) isopropyl alcohol (polar)\n(c) potassium bromide (ionic)\n"]], ["block_20", ["molecular explanation for the difference between these two types of spontaneous processes.\n"]], ["block_21", ["hydrogen in the palladium depends on the pressure of H2 gas applied, but in a more complex fashion than\ncan be described by Henry\u2019s law. Under certain conditions, 0.94 g of hydrogen gas is dissolved in 215 g of\npalladium metal (solution density = 10.8 g cm).\n(a) Determine the molarity of this solution.\n(b) Determine the molality of this solution.\n(c) Determine the percent by mass of hydrogen atoms in this solution.\n"]], ["block_22", ["nonpolar molecules.\n"]], ["block_23", ["(a polar solvent) are conductive.\n"]], ["block_24", ["technological applications.\n"]]], "page_608": [["block_0", [" 11 . Consider the solutions presented:\n"]], ["block_1", [" 12 . Compare the processes that occur when methanol (CH3OH), hydrogen chloride (HCl), and sodium\n"]], ["block_2", [" 13 . What is the expected electrical conductivity of the following solutions?\n"]], ["block_3", [" 14 . Why are most solid ionic compounds electrically nonconductive, whereas aqueous solutions of ionic\n"]], ["block_4", [" 15 . Indicate the most important type of intermolecular attraction responsible for solvation in each of the\n"]], ["block_5", [" 11.3 Solubility \n"]], ["block_6", [" 16 . Suppose you are presented with a clear solution of sodium thiosulfate, Na2S2O3. How could you determine\n"]], ["block_7", [" 17 . Supersaturated solutions of most solids in water are prepared by cooling saturated solutions.\n"]], ["block_8", [" 18 . Suggest an explanation for the observations that ethanol, C2H5OH, is completely miscible with water and\n"]], ["block_9", [" 19 . Calculate the percent by mass of KBr in a saturated solution of KBr in water at 10 \u00b0C. See Figure 11.16 for\n"]], ["block_10", [" 20 . Which of the following gases is expected to be most soluble in water? Explain your reasoning.\n"]], ["block_11", [" 21 . At 0 \u00b0C and 1.00 atm, as much as 0.70 g of O2 can dissolve in 1 L of water. At 0 \u00b0C and 4.00 atm, how many\n"]], ["block_12", ["(a) Which of the following sketches best represents the ions in a solution of Fe(NO3)3(aq)?\n"]], ["block_13", [{"image_0": "608_0.png", "coords": [91, 82, 559, 239]}]], ["block_14", ["(b) Write a balanced chemical equation showing the products of the dissolution of Fe(NO3)3.\n"]], ["block_15", ["hydroxide (NaOH) dissolve in water. Write equations and prepare sketches showing the form in which\neach of these compounds is present in its respective solution.\n"]], ["block_16", ["(a) NaOH(aq)\n(b) HCl(aq)\n(c) C6H12O6(aq) (glucose)\n(d) NH3(aq)\n"]], ["block_17", ["compounds are good conductors? Would you expect a liquid (molten) ionic compound to be electrically\nconductive or nonconductive? Explain.\n"]], ["block_18", ["following solutions:\n(a) the solutions in Figure 11.7\n(b) methanol, CH3OH, dissolved in ethanol, C2H5OH\n(c) methane, CH4, dissolved in benzene, C6H6\n(d) the polar halocarbon CF2Cl2 dissolved in the polar halocarbon CF2ClCFCl2\n(e) O2(l) in N2(l)\n"]], ["block_19", ["whether the solution is unsaturated, saturated, or supersaturated?\n"]], ["block_20", ["Supersaturated solutions of most gases in water are prepared by heating saturated solutions. Explain the\nreasons for the difference in the two procedures.\n"]], ["block_21", ["that ethanethiol, C2H5SH, is soluble only to the extent of 1.5 g per 100 mL of water.\n"]], ["block_22", ["useful data, and report the computed percentage to one significant digit.\n"]], ["block_23", ["(a) CH4\n(b) CCl4\n(c) CHCl3\n"]], ["block_24", ["grams of O2 dissolve in 1 L of water?\n"]], ["block_25", [" 11 \u2022 Exercises \n 595 \n"]]], "page_609": [["block_0", [" 596 \n 11 \u2022 Exercises \n"]], ["block_1", [" 22 . Refer to Figure 11.10.\n"]], ["block_2", [" 23 . The Henry\u2019s law constant for CO2 is 3.4\n10M/atm at 25 \u00b0C. Assuming ideal solution behavior, what\n"]], ["block_3", [" 24 . The Henry\u2019s law constant for O2 is 1.3\n10M/atm at 25 \u00b0C. Assuming ideal solution behavior, what mass\n"]], ["block_4", [" 25 . Assuming ideal solution behavior, how many liters of HCl gas, measured at 30.0 \u00b0C and 745 torr, are\n"]], ["block_5", [" 11.4 Colligative Properties \n"]], ["block_6", [" 26 . Which is/are part of the macroscopic domain of solutions and which is/are part of the microscopic\n"]], ["block_7", [" 27 . What is the microscopic explanation for the macroscopic behavior illustrated in Figure 11.14?\n 28 . Sketch a qualitative graph of the pressure versus time for water vapor above a sample of pure water and a\n"]], ["block_8", [" 29 . A solution of potassium nitrate, an electrolyte, and a solution of glycerin (C3H5(OH)3), a nonelectrolyte,\n"]], ["block_9", [" 30 . What are the mole fractions of H3PO4 and water in a solution of 14.5 g of H3PO4 in 125 g of water?\n"]], ["block_10", [" 31 . What are the mole fractions of HNO3 and water in a concentrated solution of nitric acid (68.0% HNO3 by\n"]], ["block_11", [" 32 . Calculate the mole fraction of each solute and solvent:\n"]], ["block_12", [" 33 . Calculate the mole fraction of each solute and solvent:\n"]], ["block_13", [" 34 . Calculate the mole fractions of methanol, CH3OH; ethanol, C2H5OH; and water in a solution that is 40%\n"]], ["block_14", [" 35 . What is the difference between a 1 M solution and a 1 m solution?\n 36 . What is the molality of phosphoric acid, H3PO4, in a solution of 14.5 g of H3PO4 in 125 g of water?\n"]], ["block_15", [" 37 . What is the molality of nitric acid in a concentrated solution of nitric acid (68.0% HNO3 by mass)?\n"]], ["block_16", [" 38 . Calculate the molality of each of the following solutions:\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["(a) How did the concentration of dissolved CO2 in the beverage change when the bottle was opened?\n(b) What caused this change?\n(c) Is the beverage unsaturated, saturated, or supersaturated with CO2?\n"]], ["block_19", ["pressure of carbon dioxide is needed to maintain a CO2 concentration of 0.10 M in a can of lemon-lime\nsoda?\n"]], ["block_20", ["of oxygen would be dissolved in a 40-L aquarium at 25 \u00b0C, assuming an atmospheric pressure of 1.00 atm,\nand that the partial pressure of O2 is 0.21 atm?\n"]], ["block_21", ["required to prepare 1.25 L of a 3.20-M solution of hydrochloric acid?\n"]], ["block_22", ["domain: boiling point elevation, Henry\u2019s law, hydrogen bond, ion-dipole attraction, molarity,\nnonelectrolyte, nonstoichiometric compound, osmosis, solvated ion?\n"]], ["block_23", ["sugar solution, as the liquids evaporate to half their original volume.\n"]], ["block_24", ["both boil at 100.3 \u00b0C. What other physical properties of the two solutions are identical?\n"]], ["block_25", ["(a) Outline the steps necessary to answer the question.\n(b) Answer the question.\n"]], ["block_26", ["mass)?\n(a) Outline the steps necessary to answer the question.\n(b) Answer the question.\n"]], ["block_27", ["(a) 583 g of H2SO4 in 1.50 kg of water\u2014the acid solution used in an automobile battery\n(b) 0.86 g of NaCl in 1.00\n10g of water\u2014a solution of sodium chloride for intravenous injection\n"]], ["block_28", ["(c) 46.85 g of codeine, C18H21NO3, in 125.5 g of ethanol, C2H5OH\n(d) 25 g of I2 in 125 g of ethanol, C2H5OH\n"]], ["block_29", ["(a) 0.710 kg of sodium carbonate (washing soda), Na2CO3, in 10.0 kg of water\u2014a saturated solution at 0 \u00b0C\n(b) 125 g of NH4NO3 in 275 g of water\u2014a mixture used to make an instant ice pack\n(c) 25 g of Cl2 in 125 g of dichloromethane, CH2Cl2\n(d) 0.372 g of tetrahydropyridine, C5H9N, in 125 g of chloroform, CHCl3\n"]], ["block_30", ["methanol, 40% ethanol, and 20% water by mass. (Assume the data are good to two significant figures.)\n"]], ["block_31", ["(a) Outline the steps necessary to answer the question.\n(b) Answer the question.\n"]], ["block_32", ["(a) Outline the steps necessary to answer the question.\n(b) Answer the question.\n"]], ["block_33", ["(a) 583 g of H2SO4 in 1.50 kg of water\u2014the acid solution used in an automobile battery\n(b) 0.86 g of NaCl in 1.00\n10g of water\u2014a solution of sodium chloride for intravenous injection\n"]], ["block_34", ["(c) 46.85 g of codeine, C18H21NO3, in 125.5 g of ethanol, C2H5OH\n(d) 25 g of I2 in 125 g of ethanol, C2H5OH\n"]]], "page_610": [["block_0", [" 39 . Calculate the molality of each of the following solutions:\n"]], ["block_1", [" 40 . The concentration of glucose, C6H12O6, in normal spinal fluid is\nWhat is the molality of the\n"]], ["block_2", [" 41 . A 13.0% solution of K2CO3 by mass has a density of 1.09 g/cm. Calculate the molality of the solution.\n 42 . Why does 1 mol of sodium chloride depress the freezing point of 1 kg of water almost twice as much as 1\n"]], ["block_3", [" 43 . Assuming ideal solution behavior, what is the boiling point of a solution of 115.0 g of nonvolatile sucrose,\n"]], ["block_4", [" 44 . Assuming ideal solution behavior, what is the boiling point of a solution of 9.04 g of I2 in 75.5 g of benzene,\n"]], ["block_5", [" 45 . Assuming ideal solution behavior, what is the freezing temperature of a solution of 115.0 g of sucrose,\n"]], ["block_6", [" 46 . Assuming ideal solution behavior, what is the freezing point of a solution of 9.04 g of I2 in 75.5 g of\n"]], ["block_7", [" 47 . Assuming ideal solution behavior, what is the osmotic pressure of an aqueous solution of 1.64 g of\n"]], ["block_8", [" 48 . Assuming ideal solution behavior, what is osmotic pressure of a solution of bovine insulin (molar mass,\n"]], ["block_9", [" 49 . Assuming ideal solution behavior, what is the molar mass of a solution of 5.00 g of a compound in 25.00 g\n"]], ["block_10", [" 50 . A sample of an organic compound (a nonelectrolyte) weighing 1.35 g lowered the freezing point of 10.0 g\n"]], ["block_11", [" 51 . A 1.0 m solution of HCl in benzene has a freezing point of 0.4 \u00b0C. Is HCl an electrolyte in benzene? Explain.\n 52 . A solution contains 5.00 g of urea, CO(NH2)2, a nonvolatile compound, dissolved in 0.100 kg of water. If the\n"]], ["block_12", [" 53 . A 12.0-g sample of a nonelectrolyte is dissolved in 80.0 g of water. The solution freezes at \u22121.94 \u00b0C.\n"]], ["block_13", [" 54 . Arrange the following solutions in order by their decreasing freezing points: 0.1 m Na3PO4, 0.1 m C2H5OH,\n"]], ["block_14", [" 55 . Calculate the boiling point elevation of 0.100 kg of water containing 0.010 mol of NaCl, 0.020 mol of\n"]], ["block_15", [" 56 . How could you prepare a 3.08 m aqueous solution of glycerin, C3H8O3? Assuming ideal solution behavior,\n"]], ["block_16", ["(a) 0.710 kg of sodium carbonate (washing soda), Na2CO3, in 10.0 kg of water\u2014a saturated solution at 0\u00b0C\n(b) 125 g of NH4NO3 in 275 g of water\u2014a mixture used to make an instant ice pack\n(c) 25 g of Cl2 in 125 g of dichloromethane, CH2Cl2\n(d) 0.372 g of tetrahydropyridine, C5H9N, in 125 g of chloroform, CHCl3\n"]], ["block_17", ["solution?\n"]], ["block_18", ["mol of glycerin?\n"]], ["block_19", ["C12H22O11, in 350.0 g of water?\n(a) Outline the steps necessary to answer the question\n(b) Answer the question\n"]], ["block_20", ["assuming the I2 is nonvolatile?\n(a) Outline the steps necessary to answer the question.\n(b) Answer the question.\n"]], ["block_21", ["C12H22O11, in 350.0 g of water?\n(a) Outline the steps necessary to answer the question.\n(b) Answer the question.\n"]], ["block_22", ["benzene?\n(a) Outline the steps necessary to answer the following question.\n(b) Answer the question.\n"]], ["block_23", ["Ca(NO3)2 in water at 25 \u00b0C? The volume of the solution is 275 mL.\n(a) Outline the steps necessary to answer the question.\n(b) Answer the question.\n"]], ["block_24", ["5700 g mol) at 18 \u00b0C if 100.0 mL of the solution contains 0.103 g of the insulin?\n(a) Outline the steps necessary to answer the question.\n(b) Answer the question.\n"]], ["block_25", ["of carbon tetrachloride (bp 76.8 \u00b0C; Kb = 5.02 \u00b0C/m) that boils at 81.5 \u00b0C at 1 atm?\n(a) Outline the steps necessary to answer the question.\n(b) Solve the problem.\n"]], ["block_26", ["of benzene by 3.66 \u00b0C. Assuming ideal solution behavior, calculate the molar mass of the compound.\n"]], ["block_27", ["vapor pressure of pure water at 25 \u00b0C is 23.7 torr, what is the vapor pressure of the solution (assuming\nideal solution behavior)?\n"]], ["block_28", ["Assuming ideal solution behavior, calculate the molar mass of the substance.\n"]], ["block_29", ["0.01 m CO2, 0.15 m NaCl, and 0.2 m CaCl2.\n"]], ["block_30", ["Na2SO4, and 0.030 mol of MgCl2, assuming complete dissociation of these electrolytes and ideal solution\nbehavior.\n"]], ["block_31", ["what is the freezing point of this solution?\n"]], ["block_32", [" 11 \u2022 Exercises \n 597 \n"]]], "page_611": [["block_0", [" 598 \n 11 \u2022 Exercises \n"]], ["block_1", [" 57 . A sample of sulfur weighing 0.210 g was dissolved in 17.8 g of carbon disulfide, CS2 (Kb = 2.34 \u00b0C/m). If the\n"]], ["block_2", [" 58 . In a significant experiment performed many years ago, 5.6977 g of cadmium iodide in 44.69 g of water\n"]], ["block_3", [" 59 . Lysozyme is an enzyme that cleaves cell walls. A 0.100-L sample of a solution of lysozyme that contains\n"]], ["block_4", [" 60 . The osmotic pressure of a solution containing 7.0 g of insulin per liter is 23 torr at 25 \u00b0C. Assuming ideal\n"]], ["block_5", [" 61 . The osmotic pressure of human blood is 7.6 atm at 37 \u00b0C. What mass of glucose, C6H12O6, is required to\n"]], ["block_6", [" 62 . Assuming ideal solution behavior, what is the freezing point of a solution of dibromobenzene, C6H4Br2, in\n"]], ["block_7", [" 63 . Assuming ideal solution behavior, what is the boiling point of a solution of NaCl in water if the solution\n"]], ["block_8", [" 64 . The sugar fructose contains 40.0% C, 6.7% H, and 53.3% O by mass. A solution of 11.7 g of fructose in 325\n"]], ["block_9", [" 65 . The vapor pressure of methanol, CH3OH, is 94 torr at 20 \u00b0C. The vapor pressure of ethanol, C2H5OH, is 44\n"]], ["block_10", [" 66 . The triple point of air-free water is defined as 273.16 K. Why is it important that the water be free of air?\n 67 . Meat can be classified as fresh (not frozen) even though it is stored at \u22121 \u00b0C. Why wouldn\u2019t meat freeze at\n"]], ["block_11", [" 68 . An organic compound has a composition of 93.46% C and 6.54% H by mass. A solution of 0.090 g of this\n"]], ["block_12", [" 69 . A sample of HgCl2 weighing 9.41 g is dissolved in 32.75 g of ethanol, C2H5OH (Kb = 1.20 \u00b0C/m). The boiling\n"]], ["block_13", [" 70 . A salt is known to be an alkali metal fluoride. A quick approximate determination of freezing point\n"]], ["block_14", [" 11.5 Colloids \n"]], ["block_15", [" 71 . Identify the dispersed phase and the dispersion medium in each of the following colloidal systems: starch\n"]], ["block_16", [" 72 . Distinguish between dispersion methods and condensation methods for preparing colloidal systems.\n 73 . How do colloids differ from solutions with regard to dispersed particle size and homogeneity?\n 74 . Explain the cleansing action of soap.\n 75 . How can it be demonstrated that colloidal particles are electrically charged?\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["boiling point elevation was 0.107 \u00b0C, what is the formula of a sulfur molecule in carbon disulfide\n(assuming ideal solution behavior)?\n"]], ["block_19", ["raised the boiling point 0.181 \u00b0C. What does this suggest about the nature of a solution of CdI2?\n"]], ["block_20", ["0.0750 g of the enzyme exhibits an osmotic pressure of 1.32\n10atm at 25 \u00b0C. Assuming ideal solution\n"]], ["block_21", ["behavior, what is the molar mass of lysozyme?\n"]], ["block_22", ["solution behavior, what is the molar mass of insulin?\n"]], ["block_23", ["make 1.00 L of aqueous solution for intravenous feeding if the solution must have the same osmotic\npressure as blood at body temperature, 37 \u00b0C (assuming ideal solution behavior)?\n"]], ["block_24", ["0.250 kg of benzene, if the solution boils at 83.5 \u00b0C?\n"]], ["block_25", ["freezes at \u22120.93 \u00b0C?\n"]], ["block_26", ["g of ethanol has a boiling point of 78.59 \u00b0C. The boiling point of ethanol is 78.35 \u00b0C, and Kb for ethanol is\n1.20 \u00b0C/m. Assuming ideal solution behavior, what is the molecular formula of fructose?\n"]], ["block_27", ["torr at the same temperature.\n(a) Calculate the mole fraction of methanol and of ethanol in a solution of 50.0 g of methanol and 50.0 g of\nethanol.\n(b) Ethanol and methanol form a solution that behaves like an ideal solution. Calculate the vapor pressure\nof methanol and of ethanol above the solution at 20 \u00b0C.\n(c) Calculate the mole fraction of methanol and of ethanol in the vapor above the solution.\n"]], ["block_28", ["this temperature?\n"]], ["block_29", ["compound in 1.10 g of camphor melts at 158.4 \u00b0C. The melting point of pure camphor is 178.4 \u00b0C. Kf for\ncamphor is 37.7 \u00b0C/m. Assuming ideal solution behavior, what is the molecular formula of the solute?\nShow your calculations.\n"]], ["block_30", ["point elevation of the solution is 1.27 \u00b0C. Is HgCl2 an electrolyte in ethanol? Show your calculations.\n"]], ["block_31", ["indicates that 4 g of the salt dissolved in 100 g of water produces a solution that freezes at about \u22121.4 \u00b0C.\nAssuming ideal solution behavior, what is the formula of the salt? Show your calculations.\n"]], ["block_32", ["dispersion, smoke, fog, pearl, whipped cream, floating soap, jelly, milk, and ruby.\n"]]], "page_612": [["block_0", ["CHAPTER 12\nKinetics\n"]], ["block_1", [{"image_0": "612_0.png", "coords": [72, 104, 622, 358]}]], ["block_2", [" Figure 12.1 \nAn agama lizard basks in the sun. As its body warms, the chemical reactions of its metabolism speed\n"]], ["block_3", ["up.\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 12.1 Chemical Reaction Rates \n 12.2 Factors Affecting Reaction Rates \n 12.3 Rate Laws \n 12.4 Integrated Rate Laws \n 12.5 Collision Theory \n 12.6 Reaction Mechanisms \n 12.7 Catalysis \n"]], ["block_6", [" INTRODUCTION \n"]], ["block_7", ["heat from the sun\u2019s rays is critical to the lizard\u2019s survival. A warm lizard can move faster than a cold one\nbecause the chemical reactions that allow its muscles to move occur more rapidly at higher temperatures. A\ncold lizard is a slower lizard and an easier meal for predators.\n"]], ["block_8", ["From baking a cake to determining the useful lifespan of a bridge, rates of chemical reactions play important\nroles in our understanding of processes that involve chemical changes. Two questions are typically posed\nwhen planning to carry out a chemical reaction. The first is: \u201cWill the reaction produce the desired products in\nuseful quantities?\u201d The second question is: \u201cHow rapidly will the reaction occur?\u201d A third question is often\nasked when investigating reactions in greater detail: \u201cWhat specific molecular-level processes take place as\nthe reaction occurs?\u201d Knowing the answer to this question is of practical importance when the yield or rate of a\nreaction needs to be controlled.\n"]], ["block_9", ["The study of chemical kinetics concerns the second and third questions\u2014that is, the rate at which a reaction\nyields products and the molecular-scale means by which a reaction occurs. This chapter examines the factors\n"]], ["block_10", ["The lizard in the photograph is not simply enjoying the sunshine or working on its tan. The\n"]]], "page_613": [["block_0", [" 600 \n 12 \u2022 Kinetics \n"]], ["block_1", ["that influence the rates of chemical reactions, the mechanisms by which reactions proceed, and the\nquantitative techniques used to describe the rates at which reactions occur.\n"]], ["block_2", [" 12.1 Chemical Reaction Rates \n"]], ["block_3", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_4", ["A rate is a measure of how some property varies with time. Speed is a familiar rate that expresses the distance\ntraveled by an object in a given amount of time. Wage is a rate that represents the amount of money earned by\na person working for a given amount of time. Likewise, the rate of a chemical reaction is a measure of how\nmuch reactant is consumed, or how much product is produced, by the reaction in a given amount of time.\n"]], ["block_5", ["The rate of reaction is the change in the amount of a reactant or product per unit time. Reaction rates are\ntherefore determined by measuring the time dependence of some property that can be related to reactant or\nproduct amounts. Rates of reactions that consume or produce gaseous substances, for example, are\nconveniently determined by measuring changes in volume or pressure. For reactions involving one or more\ncolored substances, rates may be monitored via measurements of light absorption. For reactions involving\naqueous electrolytes, rates may be measured via changes in a solution\u2019s conductivity.\n"]], ["block_6", ["For reactants and products in solution, their relative amounts (concentrations) are conveniently used for\npurposes of expressing reaction rates. For example, the concentration of hydrogen peroxide, H2O2, in an\naqueous solution changes slowly over time as it decomposes according to the equation:\n"]], ["block_7", ["The rate at which the hydrogen peroxide decomposes can be expressed in terms of the rate of change of its\nconcentration, as shown here:\n"]], ["block_8", ["This mathematical representation of the change in species concentration over time is the rate expression for\nthe reaction. The brackets indicate molar concentrations, and the symbol delta (\u0394) indicates \u201cchange in.\u201d Thus,\n"]], ["block_9", ["represents the molar concentration of hydrogen peroxide at a later time t2; and \u0394[H2O2] represents the change\nin molar concentration of hydrogen peroxide during the time interval \u0394t (that is, t2 \u2212 t1). Since the reactant\nconcentration decreases as the reaction proceeds, \u0394[H2O2] is a negative quantity. Reaction rates are, by\nconvention, positive quantities, and so this negative change in concentration is multiplied by \u22121. Figure 12.2\nprovides an example of data collected during the decomposition of H2O2.\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["\u2022\nDefine chemical reaction rate\n"]], ["block_12", ["\u2022\nDerive rate expressions from the balanced equation for a given chemical reaction\n"]], ["block_13", ["\u2022\nCalculate reaction rates from experimental data\n"]], ["block_14", ["represents the molar concentration of hydrogen peroxide at some time t1; likewise,\n"]]], "page_614": [["block_0", ["This behavior indicates the reaction continually slows with time. Using the concentrations at the beginning\nand end of a time period over which the reaction rate is changing results in the calculation of an average rate \nfor the reaction over this time interval. At any specific time, the rate at which a reaction is proceeding is known\nas its instantaneous rate . The instantaneous rate of a reaction at \u201ctime zero,\u201d when the reaction commences,\nis its initial rate . Consider the analogy of a car slowing down as it approaches a stop sign. The vehicle\u2019s initial\nrate\u2014analogous to the beginning of a chemical reaction\u2014would be the speedometer reading at the moment the\ndriver begins pressing the brakes (t0). A few moments later, the instantaneous rate at a specific moment\u2014call it\nt1\u2014would be somewhat slower, as indicated by the speedometer reading at that point in time. As time passes,\nthe instantaneous rate will continue to fall until it reaches zero, when the car (or reaction) stops. Unlike\ninstantaneous speed, the car\u2019s average speed is not indicated by the speedometer; but it can be calculated as\nthe ratio of the distance traveled to the time required to bring the vehicle to a complete stop (\u0394t). Like the\ndecelerating car, the average rate of a chemical reaction will fall somewhere between its initial and final rates.\n"]], ["block_1", [" FIGURE 12.2 \nThe rate of decomposition of H2O2 in an aqueous solution decreases as the concentration of H2O2\n"]], ["block_2", ["decreases.\n"]], ["block_3", ["To obtain the tabulated results for this decomposition, the concentration of hydrogen peroxide was measured\nevery 6 hours over the course of a day at a constant temperature of 40 \u00b0C. Reaction rates were computed for\neach time interval by dividing the change in concentration by the corresponding time increment, as shown\nhere for the first 6-hour period:\n"]], ["block_4", ["Notice that the reaction rates vary with time, decreasing as the reaction proceeds. Results for the last 6-hour\nperiod yield a reaction rate of:\n"]], ["block_5", ["The instantaneous rate of a reaction may be determined one of two ways. If experimental conditions permit\nthe measurement of concentration changes over very short time intervals, then average rates computed as\ndescribed earlier provide reasonably good approximations of instantaneous rates. Alternatively, a graphical\nprocedure may be used that, in effect, yields the results that would be obtained if short time interval\nmeasurements were possible. In a plot of the concentration of hydrogen peroxide against time, the\ninstantaneous rate of decomposition of H2O2 at any time t is given by the slope of a straight line that is tangent\nto the curve at that time (Figure 12.3). These tangent line slopes may be evaluated using calculus, but the\nprocedure for doing so is beyond the scope of this chapter.\n"]], ["block_6", [{"image_0": "614_0.png", "coords": [77, 57, 534, 204]}]], ["block_7", [" 12.1 \u2022 Chemical Reaction Rates \n 601 \n"]]], "page_615": [["block_0", [" 602 \n 12 \u2022 Kinetics \n"]], ["block_1", [" FIGURE 12.3 \nThis graph shows a plot of concentration versus time for a 1.000 M solution of H2O2. The rate at any\n"]], ["block_2", ["time is equal to the negative of the slope of a line tangent to the curve at that time. Tangents are shown at t = 0 h\n(\u201cinitial rate\u201d) and at t = 12 h (\u201cinstantaneous rate\u201d at 12 h).\n"]], ["block_3", [" Access for free at openstax.org \n"]], ["block_4", ["Chemistry in Everyday Life\n"]], ["block_5", [" Reaction Rates in Analysis: Test Strips for Urinalysis \nPhysicians often use disposable test strips to measure the amounts of various substances in a patient\u2019s\nurine (Figure 12.4). These test strips contain various chemical reagents, embedded in small pads at various\nlocations along the strip, which undergo changes in color upon exposure to sufficient concentrations of\nspecific substances. The usage instructions for test strips often stress that proper read time is critical for\noptimal results. This emphasis on read time suggests that kinetic aspects of the chemical reactions\noccurring on the test strip are important considerations.\n"]], ["block_6", ["The test for urinary glucose relies on a two-step process represented by the chemical equations shown\nhere:\n"]], ["block_7", ["The first equation depicts the oxidation of glucose in the urine to yield glucolactone and hydrogen\nperoxide. The hydrogen peroxide produced subsequently oxidizes colorless iodide ion to yield brown\niodine, which may be visually detected. Some strips include an additional substance that reacts with iodine\nto produce a more distinct color change.\n"]], ["block_8", ["The two test reactions shown above are inherently very slow, but their rates are increased by special\nenzymes embedded in the test strip pad. This is an example of catalysis, a topic discussed later in this\nchapter. A typical glucose test strip for use with urine requires approximately 30 seconds for completion of\nthe color-forming reactions. Reading the result too soon might lead one to conclude that the glucose\nconcentration of the urine sample is lower than it actually is (a false-negative result). Waiting too long to\nassess the color change can lead to a false positive due to the slower (not catalyzed) oxidation of iodide ion\nby other substances found in urine.\n"]], ["block_9", [{"image_0": "615_0.png", "coords": [189, 57, 423, 221]}]]], "page_616": [["block_0", [" Relative Rates of Reaction \n"]], ["block_1", ["The rate of a reaction may be expressed as the change in concentration of any reactant or product. For any\ngiven reaction, these rate expressions are all related simply to one another according to the reaction\nstoichiometry. The rate of the general reaction\n"]], ["block_2", ["can be expressed in terms of the decrease in the concentration of A or the increase in the concentration of B.\nThese two rate expressions are related by the stoichiometry of the reaction:\n"]], ["block_3", ["Consider the reaction represented by the following equation:\n"]], ["block_4", ["The relation between the reaction rates expressed in terms of nitrogen production and ammonia\nconsumption, for example, is:\n"]], ["block_5", ["This may be represented in an abbreviated format by omitting the units of the stoichiometric factor:\n"]], ["block_6", ["Note that a negative sign has been included as a factor to account for the opposite signs of the two amount\nchanges (the reactant amount is decreasing while the product amount is increasing). For homogeneous\nreactions, both the reactants and products are present in the same solution and thus occupy the same volume,\nso the molar amounts may be replaced with molar concentrations:\n"]], ["block_7", ["Similarly, the rate of formation of H2 is three times the rate of formation of N2 because three moles of H2 are\nproduced for each mole of N2 produced.\n"]], ["block_8", ["Figure 12.5 illustrates the change in concentrations over time for the decomposition of ammonia into nitrogen\n"]], ["block_9", [" FIGURE 12.4 \nTest strips are commonly used to detect the presence of specific substances in a person\u2019s urine.\n"]], ["block_10", ["Many test strips have several pads containing various reagents to permit the detection of multiple substances on\na single strip. (credit: Iqbal Osman)\n"]], ["block_11", [{"image_0": "616_0.png", "coords": [189, 57, 423, 214]}]], ["block_12", [" 12.1 \u2022 Chemical Reaction Rates \n 603 \n"]]], "page_617": [["block_0", [" 604 \n 12 \u2022 Kinetics \n"]], ["block_1", ["and hydrogen at 1100 \u00b0C. Slopes of the tangent lines at t = 500 s show that the instantaneous rates derived\nfrom all three species involved in the reaction are related by their stoichiometric factors. The rate of hydrogen\nproduction, for example, is observed to be three times greater than that for nitrogen production:\n"]], ["block_2", [" FIGURE 12.5 \nChanges in concentrations of the reactant and products for the reaction\nThe\n"]], ["block_3", ["rates of change of the three concentrations are related by the reaction stoichiometry, as shown by the different\nslopes of the tangents at t = 500 s.\n"]], ["block_4", [" Expressions for Relative Reaction Rates \n"]], ["block_5", ["The first step in the production of nitric acid is the combustion of ammonia:\n"]], ["block_6", ["Write the equations that relate the rates of consumption of the reactants and the rates of formation of the\nproducts.\n"]], ["block_7", [" Solution \n"]], ["block_8", ["Considering the stoichiometry of this homogeneous reaction, the rates for the consumption of reactants and\nformation of products are:\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["The rate of formation of Br2 is 6.0\n10mol/L/s in a reaction described by the following net ionic equation:\n"]], ["block_11", ["Write the equations that relate the rates of consumption of the reactants and the rates of formation of the\nproducts.\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["EXAMPLE 12.1\n"]], ["block_14", [{"image_0": "617_0.png", "coords": [130, 134, 481, 395]}]]], "page_618": [["block_0", [" Answer: \n"]], ["block_1", [" Reaction Rate Expressions for Decomposition of H 2 O 2 \nThe graph in Figure 12.3 shows the rate of the decomposition of H2O2 over time:\n"]], ["block_2", ["Based on these data, the instantaneous rate of decomposition of H2O2 at t = 11.1 h is determined to be\n3.20\n10mol/L/h, that is:\n"]], ["block_3", ["What is the instantaneous rate of production of H2O and O2?\n"]], ["block_4", [" Solution \n"]], ["block_5", ["The reaction stoichiometry shows that\n"]], ["block_6", ["Therefore:\n"]], ["block_7", ["and\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["If the rate of decomposition of ammonia, NH3, at 1150 K is 2.10\n10mol/L/s, what is the rate of production\n"]], ["block_10", ["of nitrogen and hydrogen?\n"]], ["block_11", [" Answer: \n1.05\n10mol/L/s, N2 and 3.15\n10mol/L/s, H2.\n"]], ["block_12", [" 12.2 Factors Affecting Reaction Rates \n"]], ["block_13", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_14", ["The rates at which reactants are consumed and products are formed during chemical reactions vary greatly.\nFive factors typically affecting the rates of chemical reactions will be explored in this section: the chemical\nnature of the reacting substances, the state of subdivision (one large lump versus many small particles) of the\nreactants, the temperature of the reactants, the concentration of the reactants, and the presence of a catalyst.\n"]], ["block_15", [" The Chemical Nature of the Reacting Substances \n"]], ["block_16", ["The rate of a reaction depends on the nature of the participating substances. Reactions that appear similar\nmay have different rates under the same conditions, depending on the identity of the reactants. For example,\nwhen small pieces of the metals iron and sodium are exposed to air, the sodium reacts completely with air\n"]], ["block_17", ["\u2022\nDescribe the effects of chemical nature, physical state, temperature, concentration, and catalysis on reaction\nrates\n"]], ["block_18", ["EXAMPLE 12.2\n"]], ["block_19", [" 12.2 \u2022 Factors Affecting Reaction Rates \n 605 \n"]]], "page_619": [["block_0", [" 606 \n 12 \u2022 Kinetics \n"]], ["block_1", ["overnight, whereas the iron is barely affected. The active metals calcium and sodium both react with water to\nform hydrogen gas and a base. Yet calcium reacts at a moderate rate, whereas sodium reacts so rapidly that the\nreaction is almost explosive.\n"]], ["block_2", [" The Physical States of the Reactants \n"]], ["block_3", ["A chemical reaction between two or more substances requires intimate contact between the reactants. When\nreactants are in different physical states, or phases (solid, liquid, gaseous, dissolved), the reaction takes place\nonly at the interface between the phases. Consider the heterogeneous reaction between a solid phase and\neither a liquid or gaseous phase. Compared with the reaction rate for large solid particles, the rate for smaller\nparticles will be greater because the surface area in contact with the other reactant phase is greater. For\nexample, large pieces of iron react more slowly with acids than they do with finely divided iron powder (Figure\n12.6). Large pieces of wood smolder, smaller pieces burn rapidly, and saw dust burns explosively.\n"]], ["block_4", [" FIGURE 12.6 \n(a) Iron powder reacts rapidly with dilute hydrochloric acid and produces bubbles of hydrogen gas:\n"]], ["block_5", ["2Fe(s) + 6HCl(aq)\n2FeCl3(aq) + 3H2(g). (b) An iron nail reacts more slowly because the surface area exposed to\n"]], ["block_6", ["the acid is much less.\n"]], ["block_7", ["Watch this video (http://openstax.org/l/16cesium) to see the reaction of cesium with water in slow motion and a\ndiscussion of how the state of reactants and particle size affect reaction rates.\n"]], ["block_8", [" Temperature of the Reactants \n"]], ["block_9", ["Chemical reactions typically occur faster at higher temperatures. Food can spoil quickly when left on the\nkitchen counter. However, the lower temperature inside of a refrigerator slows that process so that the same\nfood remains fresh for days. Gas burners, hot plates, and ovens are often used in the laboratory to increase the\nspeed of reactions that proceed slowly at ordinary temperatures. For many chemical processes, reaction rates\nare approximately doubled when the temperature is raised by 10 \u00b0C.\n"]], ["block_10", [" Concentrations of the Reactants \n"]], ["block_11", ["The rates of many reactions depend on the concentrations of the reactants. Rates usually increase when the\nconcentration of one or more of the reactants increases. For example, calcium carbonate (CaCO3) deteriorates\nas a result of its reaction with the pollutant sulfur dioxide. The rate of this reaction depends on the amount of\nsulfur dioxide in the air (Figure 12.7). An acidic oxide, sulfur dioxide combines with water vapor in the air to\nproduce sulfurous acid in the following reaction:\n"]], ["block_12", ["Calcium carbonate reacts with sulfurous acid as follows:\n"]], ["block_13", ["In a polluted atmosphere where the concentration of sulfur dioxide is high, calcium carbonate deteriorates\nmore rapidly than in less polluted air. Similarly, phosphorus burns much more rapidly in an atmosphere of\npure oxygen than in air, which is only about 20% oxygen.\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["LINK TO LEARNING\n"]], ["block_16", [{"image_0": "619_0.png", "coords": [130, 216, 481, 341]}]]], "page_620": [["block_0", [" FIGURE 12.7 \nStatues made from carbonate compounds such as limestone and marble typically weather slowly\n"]], ["block_1", ["over time due to the actions of water, and thermal expansion and contraction. However, pollutants like sulfur dioxide\ncan accelerate weathering. As the concentration of air pollutants increases, deterioration of limestone occurs more\nrapidly. (credit: James P Fisher III)\n"]], ["block_2", ["Phosphorus burns rapidly in air, but it will burn even more rapidly if the concentration of oxygen is higher.\nWatch this video (http://openstax.org/l/16phosphor) to see an example.\n"]], ["block_3", [" The Presence of a Catalyst \n"]], ["block_4", ["Relatively dilute aqueous solutions of hydrogen peroxide, H2O2, are commonly used as topical antiseptics.\nHydrogen peroxide decomposes to yield water and oxygen gas according to the equation:\n"]], ["block_5", ["Under typical conditions, this decomposition occurs very slowly. When dilute H2O2(aq) is poured onto an open\nwound, however, the reaction occurs rapidly and the solution foams because of the vigorous production of\noxygen gas. This dramatic difference is caused by the presence of substances within the wound\u2019s exposed\ntissues that accelerate the decomposition process. Substances that function to increase the rate of a reaction\nare called catalysts , a topic treated in greater detail later in this chapter.\n"]], ["block_6", ["Chemical reactions occur when molecules collide with each other and undergo a chemical transformation.\nBefore physically performing a reaction in a laboratory, scientists can use molecular modeling simulations to\npredict how the parameters discussed earlier will influence the rate of a reaction. Use the PhET Reactions &\nRates interactive (http://openstax.org/l/16PHETreaction) to explore how temperature, concentration, and the\nnature of the reactants affect reaction rates.\n"]], ["block_7", [" 12.3 Rate Laws \n"]], ["block_8", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_9", ["As described in the previous module, the rate of a reaction is often affected by the concentrations of reactants.\n Rate laws (sometimes called differential rate laws) or rate equations are mathematical expressions that\ndescribe the relationship between the rate of a chemical reaction and the concentration of its reactants. As an\nexample, consider the reaction described by the chemical equation\n"]], ["block_10", ["\u2022\nExplain the form and function of a rate law\n"]], ["block_11", ["\u2022\nUse rate laws to calculate reaction rates\n"]], ["block_12", ["\u2022\nUse rate and concentration data to identify reaction orders and derive rate laws\n"]], ["block_13", ["LINK TO LEARNING\n"]], ["block_14", ["LINK TO LEARNING\n"]], ["block_15", [{"image_0": "620_0.png", "coords": [189, 57, 423, 213]}]], ["block_16", [" 12.3 \u2022 Rate Laws \n 607 \n"]]], "page_621": [["block_0", [" 608 \n 12 \u2022 Kinetics \n"]], ["block_1", ["where a and b are stoichiometric coefficients. The rate law for this reaction is written as:\n"]], ["block_2", ["in which [A] and [B] represent the molar concentrations of reactants, and k is the rate constant , which is\nspecific for a particular reaction at a particular temperature. The exponents m and n are the reaction orders \nand are typically positive integers, though they can be fractions, negative, or zero. The rate constant k and the\nreaction orders m and n must be determined experimentally by observing how the rate of a reaction changes\nas the concentrations of the reactants are changed. The rate constant k is independent of the reactant\nconcentrations, but it does vary with temperature.\n"]], ["block_3", ["The reaction orders in a rate law describe the mathematical dependence of the rate on reactant\nconcentrations. Referring to the generic rate law above, the reaction is m order with respect to A and n order\nwith respect to B. For example, if m = 1 and n = 2, the reaction is first order in A and second order in B. The\n overall reaction order is simply the sum of orders for each reactant. For the example rate law here, the\nreaction is third order overall (1 + 2 = 3). A few specific examples are shown below to further illustrate this\nconcept.\n"]], ["block_4", ["The rate law:\n"]], ["block_5", ["describes a reaction that is first order in hydrogen peroxide and first order overall. The rate law:\n"]], ["block_6", ["describes a reaction that is second order in C4H6 and second order overall. The rate law:\n"]], ["block_7", ["describes a reaction that is first order in H, first order in OH, and second order overall.\n"]], ["block_8", [" Writing Rate Laws from Reaction Orders \n"]], ["block_9", ["An experiment shows that the reaction of nitrogen dioxide with carbon monoxide:\n"]], ["block_10", ["is second order in NO2 and zero order in CO at 100 \u00b0C. What is the rate law for the reaction?\n"]], ["block_11", [" Solution \n"]], ["block_12", ["The reaction will have the form:\n"]], ["block_13", ["The reaction is second order in NO2; thus m = 2. The reaction is zero order in CO; thus n = 0. The rate law is:\n"]], ["block_14", ["Remember that a number raised to the zero power is equal to 1, thus [CO]= 1, which is why the CO\nconcentration term may be omitted from the rate law: the rate of reaction is solely dependent on the\nconcentration of NO2. A later chapter section on reaction mechanisms will explain how a reactant\u2019s\nconcentration can have no effect on a reaction rate despite being involved in the reaction.\n"]], ["block_15", [" Check Your Learning \n"]], ["block_16", ["The rate law for the reaction:\n"]], ["block_17", ["has been determined to be rate = k[NO][H2]. What are the orders with respect to each reactant, and what is the\n"]], ["block_18", [" Access for free at openstax.org \n"]], ["block_19", ["EXAMPLE 12.3\n"]]], "page_622": [["block_0", ["overall order of the reaction?\n"]], ["block_1", [" Answer: \norder in NO = 2; order in H2 = 1; overall order = 3\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["In a transesterification reaction, a triglyceride reacts with an alcohol to form an ester and glycerol. Many\nstudents learn about the reaction between methanol (CH3OH) and ethyl acetate (CH3CH2OCOCH3) as a sample\nreaction before studying the chemical reactions that produce biodiesel:\n"]], ["block_4", ["The rate law for the reaction between methanol and ethyl acetate is, under certain conditions, determined to\nbe:\n"]], ["block_5", ["What is the order of reaction with respect to methanol and ethyl acetate, and what is the overall order of\nreaction?\n"]], ["block_6", [" Answer: \norder in CH3OH = 1; order in CH3CH2OCOCH3 = 0; overall order = 1\n"]], ["block_7", ["A common experimental approach to the determination of rate laws is the method of initial rates . This\nmethod involves measuring reaction rates for multiple experimental trials carried out using different initial\nreactant concentrations. Comparing the measured rates for these trials permits determination of the reaction\norders and, subsequently, the rate constant, which together are used to formulate a rate law. This approach is\nillustrated in the next two example exercises.\n"]], ["block_8", [" Determining a Rate Law from Initial Rates \n"]], ["block_9", ["Ozone in the upper atmosphere is depleted when it reacts with nitrogen oxides. The rates of the reactions of\nnitrogen oxides with ozone are important factors in deciding how significant these reactions are in the\nformation of the ozone hole over Antarctica (Figure 12.8). One such reaction is the combination of nitric oxide,\nNO, with ozone, O3:\n"]], ["block_10", ["EXAMPLE 12.4\n"]], ["block_11", [" 12.3 \u2022 Rate Laws \n 609 \n"]]], "page_623": [["block_0", [" 610 \n 12 \u2022 Kinetics \n"]], ["block_1", [" FIGURE 12.8 \nA contour map showing stratospheric ozone concentration and the \u201cozone hole\u201d that occurs over\n"]], ["block_2", ["Antarctica during its spring months. (credit: modification of work by NASA)\n"]], ["block_3", ["This reaction has been studied in the laboratory, and the following rate data were determined at 25 \u00b0C.\n"]], ["block_4", ["Determine the rate law and the rate constant for the reaction at 25 \u00b0C.\n"]], ["block_5", [" Solution \n"]], ["block_6", ["The rate law will have the form:\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [{"image_0": "623_0.png", "coords": [130, 57, 481, 416]}]], ["block_9", [" Trial \n [NO] (mol/L) \n [O 3 ] (mol/L) \n"]], ["block_10", ["1\n1.00\n10\n3.00\n10\n6.60\n10\n"]], ["block_11", ["2\n1.00\n10\n6.00\n10\n1.32\n10\n"]], ["block_12", ["3\n1.00\n10\n9.00\n10\n1.98\n10\n"]], ["block_13", ["4\n2.00\n10\n9.00\n10\n3.96\n10\n"]], ["block_14", ["5\n3.00\n10\n9.00\n10\n5.94\n10\n"]]], "page_624": [["block_0", ["Determine the values of m, n, and k from the experimental data using the following three-part process:\n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["Acetaldehyde decomposes when heated to yield methane and carbon monoxide according to the equation:\n"]], ["block_3", ["Determine the rate law and the rate constant for the reaction from the following experimental data:\n"]], ["block_4", [" Answer: \n"]], ["block_5", [" Determining Rate Laws from Initial Rates \n"]], ["block_6", ["Using the initial rates method and the experimental data, determine the rate law and the value of the rate\nconstant for this reaction:\n"]], ["block_7", ["Step 1.\nDetermine the value of m from the data in which [NO] varies and [O3] is constant. In the last three\nexperiments, [NO] varies while [O3] remains constant. When [NO] doubles from trial 3 to 4, the rate\ndoubles, and when [NO] triples from trial 3 to 5, the rate also triples. Thus, the rate is also directly\nproportional to [NO], and m in the rate law is equal to 1.\n"]], ["block_8", ["Step 2.\nDetermine the value of n from data in which [O3] varies and [NO] is constant. In the first three experiments,\n[NO] is constant and [O3] varies. The reaction rate changes in direct proportion to the change in [O3]. When\n[O3] doubles from trial 1 to 2, the rate doubles; when [O3] triples from trial 1 to 3, the rate increases also\ntriples. Thus, the rate is directly proportional to [O3], and n is equal to 1.The rate law is thus:\n"]], ["block_9", ["Step 3.\nDetermine the value of k from one set of concentrations and the corresponding rate. The data from trial 1\nare used below:\n"]], ["block_10", ["EXAMPLE 12.5\n"]], ["block_11", ["with k = 6.73\n10L/mol/s\n"]], ["block_12", [" Trial \n [CH 3 CHO] (mol/L) \n"]], ["block_13", ["1\n1.75\n10\n2.06\n10\n"]], ["block_14", ["2\n3.50\n10\n8.24\n10\n"]], ["block_15", ["3\n7.00\n10\n3.30\n10\n"]], ["block_16", [" 12.3 \u2022 Rate Laws \n 611 \n"]]], "page_625": [["block_0", [" 612 \n 12 \u2022 Kinetics \n"]], ["block_1", [" Solution \n"]], ["block_2", ["The rate law for this reaction will have the form:\n"]], ["block_3", ["As in Example 12.4, approach this problem in a stepwise fashion, determining the values of m and n from the\nexperimental data and then using these values to determine the value of k. In this example, however, an\nexplicit algebraic approach (vs. the implicit approach of the previous example) will be used to determine the\nvalues of m and n:\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", ["Step 1.\nDetermine the value of m from the data in which [NO] varies and [Cl2] is constant. Write the ratios with the\nsubscripts x and y to indicate data from two different trials:\n"]], ["block_6", ["Step 2.\nDetermine the value of n from data in which [Cl2] varies and [NO] is constant.\n"]], ["block_7", ["Using the third trial and the first trial, in which [Cl2] does not vary, gives:\n"]], ["block_8", ["Canceling equivalent terms in the numerator and denominator leaves:\n"]], ["block_9", ["which simplifies to:\n"]], ["block_10", ["Use logarithms to determine the value of the exponent m:\n"]], ["block_11", ["Confirm the result\n"]], ["block_12", ["Cancelation gives:\n"]], ["block_13", [" Trial \n [NO] (mol/L) \n [Cl 2 ] (mol/L) \n"]], ["block_14", ["1\n0.10\n0.10\n0.00300\n"]], ["block_15", ["2\n0.10\n0.15\n0.00450\n"]], ["block_16", ["3\n0.15\n0.10\n0.00675\n"]]], "page_626": [["block_0", ["y = 1\n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["Use the provided initial rate data to derive the rate law for the reaction whose equation is:\n"]], ["block_3", ["Determine the rate law expression and the value of the rate constant k with appropriate units for this reaction.\n"]], ["block_4", [" Answer: \n"]], ["block_5", ["2.00 = 2.00\n"]], ["block_6", ["Substituting the concentration data from trial 1 and solving for k yields:\n"]], ["block_7", [" Reaction Order and Rate Constant Units \n"]], ["block_8", ["In some of our examples, the reaction orders in the rate law happen to be the same as the coefficients in the\n"]], ["block_9", ["Step 3.\nDetermine the numerical value of the rate constant k with appropriate units. The units for the rate of a\nreaction are mol/L/s. The units for k are whatever is needed so that substituting into the rate law\nexpression affords the appropriate units for the rate. In this example, the concentration units are mol/L.\nThe units for k should be molL/s so that the rate is in terms of mol/L/s.\n"]], ["block_10", ["which simplifies to:\n"]], ["block_11", ["Thus n must be 1, and the form of the rate law is:\n"]], ["block_12", ["To determine the value of k once the rate law expression has been solved, simply plug in values from the\nfirst experimental trial and solve for k:\n"]], ["block_13", [" Trial \n [OCl \u2212 ] (mol/L) \n [I \u2212 ] (mol/L) \n Initial Rate (mol/L/s) \n"]], ["block_14", ["1\n0.0040\n0.0020\n0.00184\n"]], ["block_15", ["2\n0.0020\n0.0040\n0.00092\n"]], ["block_16", ["3\n0.0020\n0.0020\n0.00046\n"]], ["block_17", [" 12.3 \u2022 Rate Laws \n 613 \n"]]], "page_627": [["block_0", [" 614 \n 12 \u2022 Kinetics \n"]], ["block_1", ["It is important to note that rate laws are determined by experiment only and are not reliably predicted by\nreaction stoichiometry.\n"]], ["block_2", ["chemical equation for the reaction. This is merely a coincidence and very often not the case.\n"]], ["block_3", ["Rate laws may exhibit fractional orders for some reactants, and negative reaction orders are sometimes\nobserved when an increase in the concentration of one reactant causes a decrease in reaction rate. A few\nexamples illustrating these points are provided:\n"]], ["block_4", ["The units for a rate constant will vary as appropriate to accommodate the overall order of the reaction. The\nunit of the rate constant for the second-order reaction described in Example 12.4 was determined to be\n"]], ["block_5", ["Note that the units in this table were derived using specific units for concentration (mol/L) and time (s), though\nany valid units for these two properties may be used.\n"]], ["block_6", [" 12.4 Integrated Rate Laws \n"]], ["block_7", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_8", ["The rate laws discussed thus far relate the rate and the concentrations of reactants. We can also determine a\nsecond form of each rate law that relates the concentrations of reactants and time. These are called integrated \n rate laws . We can use an integrated rate law to determine the amount of reactant or product present after a\nperiod of time or to estimate the time required for a reaction to proceed to a certain extent. For example, an\nintegrated rate law is used to determine the length of time a radioactive material must be stored for its\nradioactivity to decay to a safe level.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["\u2022\nExplain the form and function of an integrated rate law\n"]], ["block_11", ["\u2022\nPerform integrated rate law calculations for zero-, first-, and second-order reactions\n"]], ["block_12", ["\u2022\nDefine half-life and carry out related calculations\n"]], ["block_13", ["\u2022\nIdentify the order of a reaction from concentration/time data\n"]], ["block_14", ["For the third-order reaction described in Example 12.5, the unit for k was derived to be\n"]], ["block_15", ["Dimensional analysis requires the rate constant unit for a reaction whose overall order is x to be\n"]], ["block_16", ["Table 12.1 summarizes the rate constant units for common reaction orders.\n"]], ["block_17", [" TABLE 12.1 \n"]], ["block_18", [" Overall Reaction Order (x) \n Rate Constant Unit (L x\u22121 mol 1\u2212x s \u22121 ) \n"]], ["block_19", ["0 (zero)\nmol Ls\n"]], ["block_20", ["1 (first)\ns\n"]], ["block_21", ["2 (second)\nL mols\n"]], ["block_22", ["3 (third)\nLmols\n"]], ["block_23", ["Rate Constant Units for Common Reaction Orders\n"]]], "page_628": [["block_0", ["Using calculus, the differential rate law for a chemical reaction can be integrated with respect to time to give\nan equation that relates the amount of reactant or product present in a reaction mixture to the elapsed time of\nthe reaction. This process can either be very straightforward or very complex, depending on the complexity of\nthe differential rate law. For purposes of discussion, we will focus on the resulting integrated rate laws for first-\n, second-, and zero-order reactions.\n"]], ["block_1", [" First-Order Reactions \n"]], ["block_2", ["Integration of the rate law for a simple first-order reaction (rate = k[A]) results in an equation describing how\nthe reactant concentration varies with time:\n"]], ["block_3", ["where [A]t is the concentration of A at any time t, [A]0 is the initial concentration of A, and k is the first-order\nrate constant.\n"]], ["block_4", ["For mathematical convenience, this equation may be rearranged to other formats, including direct and\nindirect proportionalities:\n"]], ["block_5", ["and a format showing a linear dependence of concentration in time:\n"]], ["block_6", [" The Integrated Rate Law for a First-Order Reaction \n"]], ["block_7", ["The rate constant for the first-order decomposition of cyclobutane, C4H8 at 500 \u00b0C is 9.2\n10s:\n"]], ["block_8", ["How long will it take for 80.0% of a sample of C4H8 to decompose?\n"]], ["block_9", [" Solution \n"]], ["block_10", ["Since the relative change in reactant concentration is provided, a convenient format for the integrated rate law\nis:\n"]], ["block_11", ["The initial concentration of C4H8, [A]0, is not provided, but the provision that 80.0% of the sample has\ndecomposed is enough information to solve this problem. Let x be the initial concentration, in which case the\nconcentration after 80.0% decomposition is 20.0% of x or 0.200x. Rearranging the rate law to isolate t and\nsubstituting the provided quantities yields:\n"]], ["block_12", [" Check Your Learning \n"]], ["block_13", ["Iodine-131 is a radioactive isotope that is used to diagnose and treat some forms of thyroid cancer. Iodine-131\ndecays to xenon-131 according to the equation:\n"]], ["block_14", ["EXAMPLE 12.6\n"]], ["block_15", [" 12.4 \u2022 Integrated Rate Laws \n 615 \n"]]], "page_629": [["block_0", [" 616 \n 12 \u2022 Kinetics \n"]], ["block_1", ["A plot of ln[A]t versus t for a first-order reaction is a straight line with a slope of \u2212k and a y-intercept of ln[A]0. If\na set of rate data are plotted in this fashion but do not result in a straight line, the reaction is not first order in\nA.\n"]], ["block_2", ["The decay is first-order with a rate constant of 0.138 d. How many days will it take for 90% of the iodine\u2212131\nin a 0.500 M solution of this substance to decay to Xe-131?\n"]], ["block_3", [" Answer: \n16.7 days\n"]], ["block_4", ["In the next example exercise, a linear format for the integrated rate law will be convenient:\n"]], ["block_5", [" Graphical Determination of Reaction Order and Rate Constant \n"]], ["block_6", ["Show that the data in Figure 12.2 can be represented by a first-order rate law by graphing ln[H2O2] versus time.\nDetermine the rate constant for the decomposition of H2O2 from these data.\n"]], ["block_7", [" Solution \n"]], ["block_8", ["The data from Figure 12.2 are tabulated below, and a plot of ln[H2O2] is shown in Figure 12.9.\n"]], ["block_9", [" FIGURE 12.9 \nA linear relationship between ln[H2O2] and time suggests the decomposition of hydrogen peroxide is\n"]], ["block_10", ["a first-order reaction.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["EXAMPLE 12.7\n"]], ["block_13", [{"image_0": "629_0.png", "coords": [189, 514, 423, 681]}]], ["block_14", [" Trial \n Time (h) \n [H 2 O 2 ] (M) \n ln[H 2 O 2 ] \n"]], ["block_15", ["1\n0.00\n1.000\n0.000\n"]], ["block_16", ["2\n6.00\n0.500\n\u22120.693\n"]], ["block_17", ["3\n12.00\n0.250\n\u22121.386\n"]], ["block_18", ["4\n18.00\n0.125\n\u22122.079\n"]], ["block_19", ["5\n24.00\n0.0625\n\u22122.772\n"]]], "page_630": [["block_0", ["The plot of ln[H2O2] versus time is linear, indicating that the reaction may be described by a first-order rate\nlaw.\n"]], ["block_1", ["According to the linear format of the first-order integrated rate law, the rate constant is given by the negative of\nthis plot\u2019s slope.\n"]], ["block_2", ["The slope of this line may be derived from two values of ln[H2O2] at different values of t (one near each end of\nthe line is preferable). For example, the value of ln[H2O2] when t is 0.00 h is 0.000; the value when t = 24.00 h is\n\u22122.772\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["Graph the following data to determine whether the reaction\nis first order.\n"]], ["block_5", [" Answer: \nThe plot of ln[A]t vs. t is not linear, indicating the reaction is not first order:\n"]], ["block_6", [{"image_0": "630_0.png", "coords": [72, 505, 306, 641]}]], ["block_7", [" Second-Order Reactions \n"]], ["block_8", ["The equations that relate the concentrations of reactants and the rate constant of second-order reactions can\nbe fairly complicated. To illustrate the point with minimal complexity, only the simplest second-order\nreactions will be described here, namely, those whose rates depend on the concentration of just one reactant.\nFor these types of reactions, the differential rate law is written as:\n"]], ["block_9", [" Trial \n Time (s) \n [A] \n"]], ["block_10", ["1\n4.0\n0.220\n"]], ["block_11", ["2\n8.0\n0.144\n"]], ["block_12", ["3\n12.0\n0.110\n"]], ["block_13", ["4\n16.0\n0.088\n"]], ["block_14", ["5\n20.0\n0.074\n"]], ["block_15", [" 12.4 \u2022 Integrated Rate Laws \n 617 \n"]]], "page_631": [["block_0", [" 618 \n 12 \u2022 Kinetics \n"]], ["block_1", ["For these second-order reactions, the integrated rate law is:\n"]], ["block_2", ["where the terms in the equation have their usual meanings as defined earlier.\n"]], ["block_3", [" The Integrated Rate Law for a Second-Order Reaction \n"]], ["block_4", ["The reaction of butadiene gas (C4H6) to yield C8H12 gas is described by the equation:\n"]], ["block_5", ["This \u201cdimerization\u201d reaction is second order with a rate constant equal to 5.76\n10L molminunder\n"]], ["block_6", ["certain conditions. If the initial concentration of butadiene is 0.200 M, what is the concentration after 10.0\nmin?\n"]], ["block_7", [" Solution \n"]], ["block_8", ["For a second-order reaction, the integrated rate law is written\n"]], ["block_9", ["We know three variables in this equation: [A]0 = 0.200 mol/L, k = 5.76\n10L/mol/min, and t = 10.0 min.\n"]], ["block_10", ["Therefore, we can solve for [A], the fourth variable:\n"]], ["block_11", ["Therefore 0.179 mol/L of butadiene remain at the end of 10.0 min, compared to the 0.200 mol/L that was\noriginally present.\n"]], ["block_12", [" Check Your Learning \n"]], ["block_13", ["If the initial concentration of butadiene is 0.0200 M, what is the concentration remaining after 20.0 min?\n"]], ["block_14", [" Answer: \n0.0195 mol/L\n"]], ["block_15", ["The integrated rate law for second-order reactions has the form of the equation of a straight line:\n"]], ["block_16", ["A plot of\nversus t for a second-order reaction is a straight line with a slope of k and a y-intercept of\nIf\n"]], ["block_17", ["the plot is not a straight line, then the reaction is not second order.\n"]], ["block_18", [" Access for free at openstax.org \n"]], ["block_19", ["EXAMPLE 12.8\n"]]], "page_632": [["block_0", [" Graphical Determination of Reaction Order and Rate Constant \n"]], ["block_1", ["The data below are for the same reaction described in Example 12.8. Prepare and compare two appropriate\ndata plots to identify the reaction as being either first or second order. After identifying the reaction order,\nestimate a value for the rate constant.\n"]], ["block_2", [" Solution \n"]], ["block_3", ["In order to distinguish a first-order reaction from a second-order reaction, prepare a plot of ln[C4H6]t versus t\nand compare it to a plot of\nversus t. The values needed for these plots follow.\n"]], ["block_4", ["The plots are shown in Figure 12.10, which clearly shows the plot of ln[C4H6]t versus t is not linear, therefore\nthe reaction is not first order. The plot of\nversus t is linear, indicating that the reaction is second order.\n"]], ["block_5", ["EXAMPLE 12.9\n"]], ["block_6", [" Time (s) \n ln[C 4 H 6 ] \n"]], ["block_7", ["0\n100\n\u22124.605\n"]], ["block_8", ["1600\n198\n\u22125.289\n"]], ["block_9", ["3200\n296\n\u22125.692\n"]], ["block_10", ["4800\n395\n\u22125.978\n"]], ["block_11", ["6200\n481\n\u22126.175\n"]], ["block_12", [" Trial \n Time (s) \n [C 4 H 6 ] (M) \n"]], ["block_13", ["1\n0\n1.00\n10\n"]], ["block_14", ["2\n1600\n5.04\n10\n"]], ["block_15", ["3\n3200\n3.37\n10\n"]], ["block_16", ["4\n4800\n2.53\n10\n"]], ["block_17", ["5\n6200\n2.08\n10\n"]], ["block_18", [" 12.4 \u2022 Integrated Rate Laws \n 619 \n"]]], "page_633": [["block_0", [" 620 \n 12 \u2022 Kinetics \n"]], ["block_1", [" FIGURE 12.10 \nThese two graphs show first- and second-order plots for the dimerization of C4H6. The linear trend\n"]], ["block_2", ["in the second-order plot (right) indicates that the reaction follows second-order kinetics.\n"]], ["block_3", ["According to the second-order integrated rate law, the rate constant is equal to the slope of the\nversus t\n"]], ["block_4", ["plot. Using the data for t = 0 s and t = 6200 s, the rate constant is estimated as follows:\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["Do the following data fit a second-order rate law?\n"]], ["block_7", [" Answer: \n"]], ["block_8", ["Yes. The plot of\nvs. t is linear:\n"]], ["block_9", [{"image_0": "633_0.png", "coords": [72, 561, 306, 718]}]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [{"image_1": "633_1.png", "coords": [130, 57, 481, 185]}]], ["block_12", [" Trial \n Time (s) \n [A] (M) \n"]], ["block_13", ["1\n5\n0.952\n"]], ["block_14", ["2\n10\n0.625\n"]], ["block_15", ["3\n15\n0.465\n"]], ["block_16", ["4\n20\n0.370\n"]], ["block_17", ["5\n25\n0.308\n"]], ["block_18", ["6\n35\n0.230\n"]]], "page_634": [["block_0", ["A zero-order reaction thus exhibits a constant reaction rate, regardless of the concentration of its reactant(s).\nThis may seem counterintuitive, since the reaction rate certainly can\u2019t be finite when the reactant\nconcentration is zero. For purposes of this introductory text, it will suffice to note that zero-order kinetics are\nobserved for some reactions only under certain specific conditions. These same reactions exhibit different\nkinetic behaviors when the specific conditions aren\u2019t met, and for this reason the more prudent term pseudo-\nzero-order is sometimes used.\n"]], ["block_1", [" Zero-Order Reactions \n"]], ["block_2", ["For zero-order reactions, the differential rate law is:\n"]], ["block_3", ["The integrated rate law for a zero-order reaction is a linear function:\n"]], ["block_4", ["A plot of [A] versus t for a zero-order reaction is a straight line with a slope of \u2212k and a y-intercept of [A]0.\nFigure 12.11 shows a plot of [NH3] versus t for the thermal decomposition of ammonia at the surface of two\ndifferent heated solids. The decomposition reaction exhibits first-order behavior at a quartz (SiO2) surface, as\nsuggested by the exponentially decaying plot of concentration versus time. On a tungsten surface, however, the\nplot is linear, indicating zero-order kinetics.\n"]], ["block_5", [" Graphical Determination of Zero-Order Rate Constant \n"]], ["block_6", ["Use the data plot in Figure 12.11 to graphically estimate the zero-order rate constant for ammonia\ndecomposition at a tungsten surface.\n"]], ["block_7", [" Solution \n"]], ["block_8", ["The integrated rate law for zero-order kinetics describes a linear plot of reactant concentration, [A]t, versus\ntime, t, with a slope equal to the negative of the rate constant, \u2212k. Following the mathematical approach of\nprevious examples, the slope of the linear data plot (for decomposition on W) is estimated from the graph.\nUsing the ammonia concentrations at t = 0 and t = 1000 s:\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["The zero-order plot in Figure 12.11 shows an initial ammonia concentration of 0.0028 mol Ldecreasing\nlinearly with time for 1000 s. Assuming no change in this zero-order behavior, at what time (min) will the\nconcentration reach 0.0001 mol L?\n"]], ["block_11", [" Answer: \n35 min\n"]], ["block_12", ["EXAMPLE 12.10\n"]], ["block_13", [" 12.4 \u2022 Integrated Rate Laws \n 621 \n"]]], "page_635": [["block_0", [" 622 \n 12 \u2022 Kinetics \n"]], ["block_1", [" FIGURE 12.11 \nThe decomposition of NH3 on a tungsten (W) surface is a zero-order reaction, whereas on a quartz\n"]], ["block_2", ["(SiO2) surface, the reaction is first order.\n"]], ["block_3", [" The Half-Life of a Reaction \n"]], ["block_4", ["The half-life of a reaction (t 1/2 ) is the time required for one-half of a given amount of reactant to be consumed.\nIn each succeeding half-life, half of the remaining concentration of the reactant is consumed. Using the\ndecomposition of hydrogen peroxide (Figure 12.2) as an example, we find that during the first half-life (from\n0.00 hours to 6.00 hours), the concentration of H2O2 decreases from 1.000 M to 0.500 M. During the second\nhalf-life (from 6.00 hours to 12.00 hours), it decreases from 0.500 M to 0.250 M; during the third half-life, it\ndecreases from 0.250 M to 0.125 M. The concentration of H2O2 decreases by half during each successive\nperiod of 6.00 hours. The decomposition of hydrogen peroxide is a first-order reaction, and, as can be shown,\nthe half-life of a first-order reaction is independent of the concentration of the reactant. However, half-lives of\nreactions with other orders depend on the concentrations of the reactants.\n"]], ["block_5", [" First-Order Reactions \nAn equation relating the half-life of a first-order reaction to its rate constant may be derived from the\nintegrated rate law as follows:\n"]], ["block_6", ["Invoking the definition of half-life, symbolized\nrequires that the concentration of A at this point is one-half\n"]], ["block_7", ["its initial concentration:\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", [{"image_0": "635_0.png", "coords": [130, 57, 481, 412]}]]], "page_636": [["block_0", ["This equation describes an expected inverse relation between the half-life of the reaction and its rate constant,\nk. Faster reactions exhibit larger rate constants and correspondingly shorter half-lives. Slower reactions\nexhibit smaller rate constants and longer half-lives.\n"]], ["block_1", ["Substituting these terms into the rearranged integrated rate law and simplifying yields the equation for half-\nlife:\n"]], ["block_2", [" Calculation of a First-order Rate Constant using Half-Life \n"]], ["block_3", ["Calculate the rate constant for the first-order decomposition of hydrogen peroxide in water at 40 \u00b0C, using the\ndata given in Figure 12.12.\n"]], ["block_4", [" FIGURE 12.12 \nThe decomposition of H2O2\nat 40 \u00b0C is illustrated. The intensity of the\n"]], ["block_5", ["color symbolizes the concentration of H2O2 at the indicated times; H2O2 is actually colorless.\n"]], ["block_6", [" Solution \n"]], ["block_7", ["Inspecting the concentration/time data in Figure 12.12 shows the half-life for the decomposition of H2O2 is\n2.16\n10s:\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["The first-order radioactive decay of iodine-131 exhibits a rate constant of 0.138 d. What is the half-life for\nthis decay?\n"]], ["block_10", [" Answer: \n5.02 d.\n"]], ["block_11", [" Second-Order Reactions \nFollowing the same approach as used for first-order reactions, an equation relating the half-life of a second-\norder reaction to its rate constant and initial concentration may be derived from its integrated rate law:\n"]], ["block_12", ["or\n"]], ["block_13", ["EXAMPLE 12.11\n"]], ["block_14", [{"image_0": "636_0.png", "coords": [126, 283, 486, 396]}]], ["block_15", [" 12.4 \u2022 Integrated Rate Laws \n 623 \n"]]], "page_637": [["block_0", [" 624 \n 12 \u2022 Kinetics \n"]], ["block_1", ["Restrict t to t1/2\n"]], ["block_2", ["define [A]t as one-half [A]0\n"]], ["block_3", ["and then substitute into the integrated rate law and simplify:\n"]], ["block_4", ["For a second-order reaction,\nis inversely proportional to the concentration of the reactant, and the half-life\n"]], ["block_5", ["increases as the reaction proceeds because the concentration of reactant decreases. Unlike with first-order\nreactions, the rate constant of a second-order reaction cannot be calculated directly from the half-life unless\nthe initial concentration is known.\n"]], ["block_6", [" Zero-Order Reactions \nAs for other reaction orders, an equation for zero-order half-life may be derived from the integrated rate law:\n"]], ["block_7", ["Restricting the time and concentrations to those defined by half-life:\nand\nSubstituting\n"]], ["block_8", ["these terms into the zero-order integrated rate law yields:\n"]], ["block_9", ["As for all reaction orders, the half-life for a zero-order reaction is inversely proportional to its rate constant.\nHowever, the half-life of a zero-order reaction increases as the initial concentration increases.\n"]], ["block_10", ["Equations for both differential and integrated rate laws and the corresponding half-lives for zero-, first-, and\nsecond-order reactions are summarized in Table 12.2.\n"]], ["block_11", [" TABLE 12.2 \n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["rate law\nrate = k\nrate = k[A]\nrate = k[A]\n"]], ["block_14", ["units of rate constant\nM s\ns\nM\u22121 s\n"]], ["block_15", ["integrated rate law\n"]], ["block_16", ["Summary of Rate Laws for Zero-, First-, and Second-Order Reactions\n"]], ["block_17", [" Zero-Order \n First-Order \n Second-Order \n"]]], "page_638": [["block_0", [" TABLE 12.2 \n"]], ["block_1", [" Half-Life for Zero-Order and Second-Order Reactions \n"]], ["block_2", ["What is the half-life for the butadiene dimerization reaction described in Example 12.8?\n"]], ["block_3", [" Solution \n"]], ["block_4", ["The reaction in question is second order, is initiated with a 0.200 mol Lreactant solution, and exhibits a rate\nconstant of 0.0576 L molmin. Substituting these quantities into the second-order half-life equation:\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["What is the half-life (min) for the thermal decomposition of ammonia on tungsten (see Figure 12.11)?\n"]], ["block_7", [" Answer: \n87 min\n"]], ["block_8", [" 12.5 Collision Theory \n"]], ["block_9", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_10", ["We should not be surprised that atoms, molecules, or ions must collide before they can react with each other.\nAtoms must be close together to form chemical bonds. This simple premise is the basis for a very powerful\ntheory that explains many observations regarding chemical kinetics, including factors affecting reaction rates.\n"]], ["block_11", [" Collision theory is based on the following postulates:\n"]], ["block_12", ["We can see the importance of the two physical factors noted in postulates 2 and 3, the orientation and energy\n"]], ["block_13", ["1.\nThe rate of a reaction is proportional to the rate of reactant collisions:\n"]], ["block_14", ["2.\nThe reacting species must collide in an orientation that allows contact between the atoms that will become\nbonded together in the product.\n"]], ["block_15", ["3.\nThe collision must occur with adequate energy to permit mutual penetration of the reacting species\u2019\nvalence shells so that the electrons can rearrange and form new bonds (and new chemical species).\n"]], ["block_16", ["plot needed for linear fit of rate data\n[A] vs. t\nln[A] vs. t\nvs. t\n"]], ["block_17", ["relationship between slope of linear\nplot and rate constant\nk = \u2212slope\nk = \u2212slope\nk = slope\n"]], ["block_18", ["half-life\n"]], ["block_19", ["\u2022\nUse the postulates of collision theory to explain the effects of physical state, temperature, and concentration on\nreaction rates\n"]], ["block_20", ["\u2022\nDefine the concepts of activation energy and transition state\n"]], ["block_21", ["\u2022\nUse the Arrhenius equation in calculations relating rate constants to temperature\n"]], ["block_22", ["EXAMPLE 12.12\n"]], ["block_23", [" Zero-Order \n First-Order \n Second-Order \n"]], ["block_24", [" 12.5 \u2022 Collision Theory \n 625 \n"]]], "page_639": [["block_0", [" 626 \n 12 \u2022 Kinetics \n"]], ["block_1", ["of collisions, when we consider the reaction of carbon monoxide with oxygen:\n"]], ["block_2", ["Carbon monoxide is a pollutant produced by the combustion of hydrocarbon fuels. To reduce this pollutant,\nautomobiles have catalytic converters that use a catalyst to carry out this reaction. It is also a side reaction of\nthe combustion of gunpowder that results in muzzle flash for many firearms. If carbon monoxide and oxygen\nare present in sufficient amounts, the reaction will occur at high temperature and pressure.\n"]], ["block_3", ["The first step in the gas-phase reaction between carbon monoxide and oxygen is a collision between the two\nmolecules:\n"]], ["block_4", ["Although there are many different possible orientations the two molecules can have relative to each other,\nconsider the two presented in Figure 12.13. In the first case, the oxygen side of the carbon monoxide molecule\ncollides with the oxygen molecule. In the second case, the carbon side of the carbon monoxide molecule\ncollides with the oxygen molecule. The second case is clearly more likely to result in the formation of carbon\ndioxide, which has a central carbon atom bonded to two oxygen atoms\nThis is a rather simple\n"]], ["block_5", ["example of how important the orientation of the collision is in terms of creating the desired product of the\nreaction.\n"]], ["block_6", [" FIGURE 12.13 \nIllustrated are two collisions that might take place between carbon monoxide and oxygen\n"]], ["block_7", ["molecules. The orientation of the colliding molecules partially determines whether a reaction between the two\nmolecules will occur.\n"]], ["block_8", ["If the collision does take place with the correct orientation, there is still no guarantee that the reaction will\nproceed to form carbon dioxide. In addition to a proper orientation, the collision must also occur with\nsufficient energy to result in product formation. When reactant species collide with both proper orientation\nand adequate energy, they combine to form an unstable species called an activated complex or a transition \n state . These species are very short lived and usually undetectable by most analytical instruments. In some\ncases, sophisticated spectral measurements have been used to observe transition states.\n"]], ["block_9", ["Collision theory explains why most reaction rates increase as concentrations increase. With an increase in the\nconcentration of any reacting substance, the chances for collisions between molecules are increased because\nthere are more molecules per unit of volume. More collisions mean a faster reaction rate, assuming the energy\nof the collisions is adequate.\n"]], ["block_10", [" Activation Energy and the Arrhenius Equation \n"]], ["block_11", ["The minimum energy necessary to form a product during a collision between reactants is called the activation \n energy (E a ) . How this energy compares to the kinetic energy provided by colliding reactant molecules is a\nprimary factor affecting the rate of a chemical reaction. If the activation energy is much larger than the\naverage kinetic energy of the molecules, the reaction will occur slowly since only a few fast-moving molecules\nwill have enough energy to react. If the activation energy is much smaller than the average kinetic energy of\nthe molecules, a large fraction of molecules will be adequately energetic and the reaction will proceed rapidly.\n"]], ["block_12", ["Figure 12.14 shows how the energy of a chemical system changes as it undergoes a reaction converting\nreactants to products according to the equation\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", [{"image_0": "639_0.png", "coords": [189, 292, 422, 403]}]]], "page_640": [["block_0", ["These reaction diagrams are widely used in chemical kinetics to illustrate various properties of the reaction\nof interest. Viewing the diagram from left to right, the system initially comprises reactants only, A + B. Reactant\nmolecules with sufficient energy can collide to form a high-energy activated complex or transition state. The\nunstable transition state can then subsequently decay to yield stable products, C + D. The diagram depicts the\nreaction's activation energy, Ea, as the energy difference between the reactants and the transition state. Using a\nspecific energy, the enthalpy (see chapter on thermochemistry), the enthalpy change of the reaction, \u0394H, is\nestimated as the energy difference between the reactants and products. In this case, the reaction is exothermic\n(\u0394H < 0) since it yields a decrease in system enthalpy.\n"]], ["block_1", ["The Arrhenius equation relates the activation energy and the rate constant, k, for many chemical reactions:\n"]], ["block_2", ["In this equation, R is the ideal gas constant, which has a value 8.314 J/mol/K, T is temperature on the Kelvin\nscale, Ea is the activation energy in joules per mole, e is the constant 2.7183, and A is a constant called the\n frequency factor , which is related to the frequency of collisions and the orientation of the reacting molecules.\n"]], ["block_3", ["Postulates of collision theory are nicely accommodated by the Arrhenius equation. The frequency factor, A,\nreflects how well the reaction conditions favor properly oriented collisions between reactant molecules. An\nincreased probability of effectively oriented collisions results in larger values for A and faster reaction rates.\n"]], ["block_4", ["The exponential term, e, describes the effect of activation energy on reaction rate. According to kinetic\nmolecular theory (see chapter on gases), the temperature of matter is a measure of the average kinetic energy\nof its constituent atoms or molecules. The distribution of energies among the molecules composing a sample\nof matter at any given temperature is described by the plot shown in Figure 12.15( a ). Two shaded areas under\nthe curve represent the numbers of molecules possessing adequate energy (RT) to overcome the activation\nbarriers (Ea). A lower activation energy results in a greater fraction of adequately energized molecules and a\nfaster reaction.\n"]], ["block_5", ["The exponential term also describes the effect of temperature on reaction rate. A higher temperature\nrepresents a correspondingly greater fraction of molecules possessing sufficient energy (RT) to overcome the\nactivation barrier (Ea), as shown in Figure 12.15( b ). This yields a greater value for the rate constant and a\ncorrespondingly faster reaction rate.\n"]], ["block_6", [" FIGURE 12.14 \nReaction diagram for the exothermic reaction\n"]], ["block_7", [{"image_0": "640_0.png", "coords": [189, 164, 423, 349]}]], ["block_8", [" 12.5 \u2022 Collision Theory \n 627 \n"]]], "page_641": [["block_0", [" 628 \n 12 \u2022 Kinetics \n"]], ["block_1", [" FIGURE 12.15 \nMolecular energy distributions showing numbers of molecules with energies exceeding (a) two\n"]], ["block_2", ["different activation energies at a given temperature, and (b) a given activation energy at two different temperatures.\n"]], ["block_3", ["A convenient approach for determining Ea for a reaction involves the measurement of k at two or more\ndifferent temperatures and using an alternate version of the Arrhenius equation that takes the form of a linear\nequation\n"]], ["block_4", ["A plot of ln k versus\nis linear with a slope equal to\nand a y-intercept equal to ln A.\n"]], ["block_5", [" Determination of E a \nThe variation of the rate constant with temperature for the decomposition of HI(g) to H2(g) and I2(g) is given\nhere. What is the activation energy for the reaction?\n"]], ["block_6", [" Solution \n"]], ["block_7", ["Use the provided data to derive values of\nand ln k:\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["EXAMPLE 12.13\n"]], ["block_10", [{"image_0": "641_0.png", "coords": [130, 57, 481, 192]}]], ["block_11", ["1.80\n10\n\u221214.860\n"]], ["block_12", ["1.74\n10\n\u221213.617\n"]], ["block_13", [" T (K) \n k (L/mol/s) \n"]], ["block_14", ["555\n3.52\n10\n"]], ["block_15", ["575\n1.22\n10\n"]], ["block_16", ["645\n8.59\n10\n"]], ["block_17", ["700\n1.16\n10\n"]], ["block_18", ["781\n3.95\n10\n"]], ["block_19", [" ln k \n"]]], "page_642": [["block_0", ["Figure 12.16 is a graph of ln k versus\nIn practice, the equation of the line (slope and y-intercept) that best\n"]], ["block_1", ["fits these plotted data points would be derived using a statistical process called regression. This is helpful for\nmost experimental data because a perfect fit of each data point with the line is rarely encountered. For the data\nhere, the fit is nearly perfect and the slope may be estimated using any two of the provided data pairs. Using\nthe first and last data points permits estimation of the slope.\n"]], ["block_2", [" FIGURE 12.16 \nThis graph shows the linear relationship between ln k and\nfor the reaction\n"]], ["block_3", ["according to the Arrhenius equation.\n"]], ["block_4", ["Alternative approach: A more expedient approach involves deriving activation energy from measurements of\nthe rate constant at just two temperatures. In this approach, the Arrhenius equation is rearranged to a\nconvenient two-point form:\n"]], ["block_5", [{"image_0": "642_0.png", "coords": [189, 248, 423, 469]}]], ["block_6", ["1.55\n10\n\u22129.362\n"]], ["block_7", ["1.43\n10\n\u22126.759\n"]], ["block_8", ["1.28\n10\n\u22123.231\n"]], ["block_9", [" ln k \n"]], ["block_10", [" 12.5 \u2022 Collision Theory \n 629 \n"]]], "page_643": [["block_0", [" 630 \n 12 \u2022 Kinetics \n"]], ["block_1", ["Rearranging this equation to isolate activation energy yields:\n"]], ["block_2", ["Any two data pairs may be substituted into this equation\u2014for example, the first and last entries from the above\ndata table:\n"]], ["block_3", ["and the result is Ea = 1.8\n10J molor 180 kJ mol\n"]], ["block_4", ["This approach yields the same result as the more rigorous graphical approach used above, as expected. In\npractice, the graphical approach typically provides more reliable results when working with actual\nexperimental data.\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["The rate constant for the rate of decomposition of N2O5 to NO and O2 in the gas phase is 1.66 L/mol/s at 650 K\nand 7.39 L/mol/s at 700 K:\n"]], ["block_7", ["Assuming the kinetics of this reaction are consistent with the Arrhenius equation, calculate the activation\nenergy for this decomposition.\n"]], ["block_8", [" Answer: \n1.1\n10J molor 110 kJ mol\n"]], ["block_9", [" 12.6 Reaction Mechanisms \n"]], ["block_10", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_11", ["Chemical reactions very often occur in a step-wise fashion, involving two or more distinct reactions taking\nplace in sequence. A balanced equation indicates what is reacting and what is produced, but it reveals no\ndetails about how the reaction actually takes place. The reaction mechanism (or reaction path) provides\ndetails regarding the precise, step-by-step process by which a reaction occurs.\n"]], ["block_12", ["The decomposition of ozone, for example, appears to follow a mechanism with two steps:\n"]], ["block_13", ["Each of the steps in a reaction mechanism is an elementary reaction . These elementary reactions occur\nprecisely as represented in the step equations, and they must sum to yield the balanced chemical equation\nrepresenting the overall reaction:\n"]], ["block_14", ["Notice that the oxygen atom produced in the first step of this mechanism is consumed in the second step and\ntherefore does not appear as a product in the overall reaction. Species that are produced in one step and\nconsumed in a subsequent step are called intermediates .\n"]], ["block_15", ["While the overall reaction equation for the decomposition of ozone indicates that two molecules of ozone react\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["\u2022\nDistinguish net reactions from elementary reactions (steps)\n"]], ["block_18", ["\u2022\nIdentify the molecularity of elementary reactions\n"]], ["block_19", ["\u2022\nWrite a balanced chemical equation for a process given its reaction mechanism\n"]], ["block_20", ["\u2022\nDerive the rate law consistent with a given reaction mechanism\n"]]], "page_644": [["block_0", ["to give three molecules of oxygen, the mechanism of the reaction does not involve the direct collision and\nreaction of two ozone molecules. Instead, one O3 decomposes to yield O2 and an oxygen atom, and a second O3\nmolecule subsequently reacts with the oxygen atom to yield two additional O2 molecules.\n"]], ["block_1", ["Unlike balanced equations representing an overall reaction, the equations for elementary reactions are\nexplicit representations of the chemical change taking place. The reactant(s) in an elementary reaction\u2019s\nequation undergo only the bond-breaking and/or making events depicted to yield the product(s). For this\nreason, the rate law for an elementary reaction may be derived directly from the balanced chemical equation\ndescribing the reaction. This is not the case for typical chemical reactions, for which rate laws may be reliably\ndetermined only via experimentation.\n"]], ["block_2", [" Unimolecular Elementary Reactions \n"]], ["block_3", ["The molecularity of an elementary reaction is the number of reactant species (atoms, molecules, or ions). For\nexample, a unimolecular reaction involves the reaction of a single reactant species to produce one or more\nmolecules of product:\n"]], ["block_4", ["The rate law for a unimolecular reaction is first order:\n"]], ["block_5", ["A unimolecular reaction may be one of several elementary reactions in a complex mechanism. For example,\nthe reaction:\n"]], ["block_6", ["illustrates a unimolecular elementary reaction that occurs as one part of a two-step reaction mechanism as\ndescribed above. However, some unimolecular reactions may be the only step of a single-step reaction\nmechanism. (In other words, an \u201coverall\u201d reaction may also be an elementary reaction in some cases.) For\nexample, the gas-phase decomposition of cyclobutane, C4H8, to ethylene, C2H4, is represented by the following\nchemical equation:\n"]], ["block_7", [{"image_0": "644_0.png", "coords": [72, 416, 306, 489]}]], ["block_8", ["This equation represents the overall reaction observed, and it might also represent a legitimate unimolecular\nelementary reaction. The rate law predicted from this equation, assuming it is an elementary reaction, turns\nout to be the same as the rate law derived experimentally for the overall reaction, namely, one showing first-\norder behavior:\n"]], ["block_9", ["This agreement between observed and predicted rate laws is interpreted to mean that the proposed\nunimolecular, single-step process is a reasonable mechanism for the butadiene reaction.\n"]], ["block_10", [" Bimolecular Elementary Reactions \n"]], ["block_11", ["A bimolecular reaction involves two reactant species, for example:\n"]], ["block_12", ["For the first type, in which the two reactant molecules are different, the rate law is first-order in A and first\norder in B (second-order overall):\n"]], ["block_13", [" 12.6 \u2022 Reaction Mechanisms \n 631 \n"]]], "page_645": [["block_0", [" 632 \n 12 \u2022 Kinetics \n"]], ["block_1", ["For the second type, in which two identical molecules collide and react, the rate law is second order in A:\n"]], ["block_2", ["Some chemical reactions occur by mechanisms that consist of a single bimolecular elementary reaction. One\nexample is the reaction of nitrogen dioxide with carbon monoxide:\n"]], ["block_3", ["(see Figure 12.17)\n"]], ["block_4", ["Bimolecular elementary reactions may also be involved as steps in a multistep reaction mechanism. The\nreaction of atomic oxygen with ozone is the second step of the two-step ozone decomposition mechanism\ndiscussed earlier in this section:\n"]], ["block_5", [" Termolecular Elementary Reactions \n"]], ["block_6", ["An elementary termolecular reaction involves the simultaneous collision of three atoms, molecules, or ions.\nTermolecular elementary reactions are uncommon because the probability of three particles colliding\nsimultaneously is less than one one-thousandth of the probability of two particles colliding. There are,\nhowever, a few established termolecular elementary reactions. The reaction of nitric oxide with oxygen\nappears to involve termolecular steps:\n"]], ["block_7", ["Likewise, the reaction of nitric oxide with chlorine appears to involve termolecular steps:\n"]], ["block_8", [" Relating Reaction Mechanisms to Rate Laws \n"]], ["block_9", ["It\u2019s often the case that one step in a multistep reaction mechanism is significantly slower than the others.\nBecause a reaction cannot proceed faster than its slowest step, this step will limit the rate at which the overall\nreaction occurs. The slowest step is therefore called the rate-limiting step (or rate-determining step) of the\nreaction Figure 12.18.\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [{"image_0": "645_0.png", "coords": [72, 178, 539, 240]}]], ["block_12", [" FIGURE 12.17 \nThe probable mechanism for the reaction between NO2 and CO to yield NO and CO2.\n"]]], "page_646": [["block_0", [" FIGURE 12.18 \nA cattle chute is a nonchemical example of a rate-determining step. Cattle can only be moved from\n"]], ["block_1", ["one holding pen to another as quickly as one animal can make its way through the chute. (credit: Loren Kerns)\n"]], ["block_2", ["As described earlier, rate laws may be derived directly from the chemical equations for elementary reactions.\nThis is not the case, however, for ordinary chemical reactions. The balanced equations most often encountered\nrepresent the overall change for some chemical system, and very often this is the result of some multistep\nreaction mechanisms. In every case, the rate law must be determined from experimental data and the reaction\nmechanism subsequently deduced from the rate law (and sometimes from other data). The reaction of NO2\nand CO provides an illustrative example:\n"]], ["block_3", ["For temperatures above 225 \u00b0C, the rate law has been found to be:\n"]], ["block_4", ["The reaction is first order with respect to NO2 and first-order with respect to CO. This is consistent with a\nsingle-step bimolecular mechanism and it is possible that this is the mechanism for this reaction at high\ntemperatures.\n"]], ["block_5", ["At temperatures below 225 \u00b0C, the reaction is described by a rate law that is second order with respect to NO2:\n"]], ["block_6", ["This rate law is not consistent with the single-step mechanism, but is consistent with the following two-step\nmechanism:\n"]], ["block_7", ["The rate-determining (slower) step gives a rate law showing second-order dependence on the NO2\nconcentration, and the sum of the two equations gives the net overall reaction.\n"]], ["block_8", ["In general, when the rate-determining (slower) step is the first step in a mechanism, the rate law for the overall\nreaction is the same as the rate law for this step. However, when the rate-determining step is preceded by a\nstep involving a rapidly reversible reaction the rate law for the overall reaction may be more difficult to derive.\n"]], ["block_9", ["As discussed in several chapters of this text, a reversible reaction is at equilibrium when the rates of the\nforward and reverse processes are equal. Consider the reversible elementary reaction in which NO dimerizes\nto yield an intermediate species N2O2. When this reaction is at equilibrium:\n"]], ["block_10", ["This expression may be rearranged to express the concentration of the intermediate in terms of the reactant\nNO:\n"]], ["block_11", [{"image_0": "646_0.png", "coords": [189, 57, 423, 214]}]], ["block_12", [" 12.6 \u2022 Reaction Mechanisms \n 633 \n"]]], "page_647": [["block_0", [" 634 \n 12 \u2022 Kinetics \n"]], ["block_1", ["Since intermediate species concentrations are not used in formulating rate laws for overall reactions, this\napproach is sometimes necessary, as illustrated in the following example exercise.\n"]], ["block_2", [" Deriving a Rate Law from a Reaction Mechanism \n"]], ["block_3", ["The two-step mechanism below has been proposed for a reaction between nitrogen monoxide and molecular\nchlorine:\n"]], ["block_4", ["Use this mechanism to derive the equation and predicted rate law for the overall reaction.\n"]], ["block_5", [" Solution \n"]], ["block_6", ["The equation for the overall reaction is obtained by adding the two elementary reactions:\n"]], ["block_7", ["To derive a rate law from this mechanism, first write rates laws for each of the two steps.\n"]], ["block_8", ["Step 2 is the rate-determining step, and so the rate law for the overall reaction should be the same as for this\nstep. However, the step 2 rate law, as written, contains an intermediate species concentration, [NOCl2]. To\nremedy this, use the first step\u2019s rate laws to derive an expression for the intermediate concentration in terms of\nthe reactant concentrations.\n"]], ["block_9", ["Assuming step 1 is at equilibrium:\n"]], ["block_10", ["Substituting this expression into the rate law for step 2 yields:\n"]], ["block_11", [" Check Your Learning \n"]], ["block_12", ["The first step of a proposed multistep mechanism is:\n"]], ["block_13", ["Derive the equation relating atomic fluorine concentration to molecular fluorine concentration.\n"]], ["block_14", [" Answer: \n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["EXAMPLE 12.14\n"]]], "page_648": [["block_0", ["Among the factors affecting chemical reaction rates discussed earlier in this chapter was the presence of a\ncatalyst, a substance that can increase the reaction rate without being consumed in the reaction. The concepts\nintroduced in the previous section on reaction mechanisms provide the basis for understanding how catalysts\nare able to accomplish this very important function.\n"]], ["block_1", [" 12.7 Catalysis \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["Figure 12.19 shows reaction diagrams for a chemical process in the absence and presence of a catalyst.\nInspection of the diagrams reveals several traits of these reactions. Consistent with the fact that the two\ndiagrams represent the same overall reaction, both curves begin and end at the same energies (in this case,\nbecause products are more energetic than reactants, the reaction is endothermic). The reaction mechanisms,\nhowever, are clearly different. The uncatalyzed reaction proceeds via a one-step mechanism (one transition\nstate observed), whereas the catalyzed reaction follows a two-step mechanism (two transition states observed)\nwith a notably lesser activation energy. This difference illustrates the means by which a catalyst functions to\naccelerate reactions, namely, by providing an alternative reaction mechanism with a lower activation energy.\nAlthough the catalyzed reaction mechanism for a reaction needn\u2019t necessarily involve a different number of\nsteps than the uncatalyzed mechanism, it must provide a reaction path whose rate determining step is faster\n(lower Ea).\n"]], ["block_4", [" FIGURE 12.19 \nReaction diagrams for an endothermic process in the absence (red curve) and presence (blue\n"]], ["block_5", ["curve) of a catalyst. The catalyzed pathway involves a two-step mechanism (note the presence of two transition\nstates) and an intermediate species (represented by the valley between the two transitions states).\n"]], ["block_6", [" Reaction Diagrams for Catalyzed Reactions \n"]], ["block_7", ["The two reaction diagrams here represent the same reaction: one without a catalyst and one with a catalyst.\nEstimate the activation energy for each process, and identify which one involves a catalyst.\n"]], ["block_8", ["\u2022\nExplain the function of a catalyst in terms of reaction mechanisms and potential energy diagrams\n"]], ["block_9", ["\u2022\nList examples of catalysis in natural and industrial processes\n"]], ["block_10", ["EXAMPLE 12.15\n"]], ["block_11", [{"image_0": "648_0.png", "coords": [189, 339, 423, 543]}]], ["block_12", [" 12.7 \u2022 Catalysis \n 635 \n"]]], "page_649": [["block_0", [" 636 \n 12 \u2022 Kinetics \n"]], ["block_1", [{"image_0": "649_0.png", "coords": [72, 57, 495, 211]}]], ["block_2", [" Solution \n"]], ["block_3", ["Activation energies are calculated by subtracting the reactant energy from the transition state energy.\n"]], ["block_4", ["The catalyzed reaction is the one with lesser activation energy, in this case represented by diagram b.\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["Reaction diagrams for a chemical process with and without a catalyst are shown below. Both reactions involve\na two-step mechanism with a rate-determining first step. Compute activation energies for the first step of each\nmechanism, and identify which corresponds to the catalyzed reaction. How do the second steps of these two\nmechanisms compare?\n"]], ["block_7", [{"image_1": "649_1.png", "coords": [72, 373, 495, 527]}]], ["block_8", [" Answer: \nFor the first step, Ea = 80 kJ for (a) and 70 kJ for (b), so diagram (b) depicts the catalyzed reaction. Activation\nenergies for the second steps of both mechanisms are the same, 20 kJ.\n"]], ["block_9", [" Homogeneous Catalysts \n"]], ["block_10", ["A homogeneous catalyst is present in the same phase as the reactants. It interacts with a reactant to form an\nintermediate substance, which then decomposes or reacts with another reactant in one or more steps to\nregenerate the original catalyst and form product.\n"]], ["block_11", ["As an important illustration of homogeneous catalysis, consider the earth\u2019s ozone layer. Ozone in the upper\natmosphere, which protects the earth from ultraviolet radiation, is formed when oxygen molecules absorb\nultraviolet light and undergo the reaction:\n"]], ["block_12", ["Ozone is a relatively unstable molecule that decomposes to yield diatomic oxygen by the reverse of this\n"]], ["block_13", [" Access for free at openstax.org \n"]]], "page_650": [["block_0", ["equation. This decomposition reaction is consistent with the following two-step mechanism:\n"]], ["block_1", ["A number of substances can catalyze the decomposition of ozone. For example, the nitric oxide\u2013catalyzed\ndecomposition of ozone is believed to occur via the following three-step mechanism:\n"]], ["block_2", ["As required, the overall reaction is the same for both the two-step uncatalyzed mechanism and the three-step\nNO-catalyzed mechanism:\n"]], ["block_3", ["Notice that NO is a reactant in the first step of the mechanism and a product in the last step. This is another\ncharacteristic trait of a catalyst: Though it participates in the chemical reaction, it is not consumed by the\nreaction.\n"]], ["block_4", ["1 \u201cThe Nobel Prize in Chemistry 1995,\u201d Nobel Prize.org, accessed February 18, 2015, http://www.nobelprize.org/nobel_prizes/\nchemistry/laureates/1995/.\n"]], ["block_5", ["Portrait of a Chemist\n"]], ["block_6", [" Mario J. Molina \nThe 1995 Nobel Prize in Chemistry was shared by Paul J. Crutzen, Mario J. Molina (Figure 12.20), and F.\nSherwood Rowland \u201cfor their work in atmospheric chemistry, particularly concerning the formation and\ndecomposition of ozone.\u201dMolina, a Mexican citizen, carried out the majority of his work at the\nMassachusetts Institute of Technology (MIT).\n"]], ["block_7", [" FIGURE 12.20 \n(a) Mexican chemist Mario Molina (1943 \u2013) shared the Nobel Prize in Chemistry in 1995 for his\n"]], ["block_8", ["research on (b) the Antarctic ozone hole. (credit a: courtesy of Mario Molina; credit b: modification of work by\nNASA)\n"]], ["block_9", ["In 1974, Molina and Rowland published a paper in the journal Nature detailing the threat of\nchlorofluorocarbon gases to the stability of the ozone layer in earth\u2019s upper atmosphere. The ozone layer\nprotects earth from solar radiation by absorbing ultraviolet light. As chemical reactions deplete the amount\nof ozone in the upper atmosphere, a measurable \u201chole\u201d forms above Antarctica, and an increase in the\n"]], ["block_10", [{"image_0": "650_0.png", "coords": [90, 408, 522, 592]}]], ["block_11", [" 12.7 \u2022 Catalysis \n 637 \n"]]], "page_651": [["block_0", [" 638 \n 12 \u2022 Kinetics \n"]], ["block_1", [" Glucose-6-Phosphate Dehydrogenase Deficiency \nEnzymes in the human body act as catalysts for important chemical reactions in cellular metabolism. As such,\na deficiency of a particular enzyme can translate to a life-threatening disease. G6PD (glucose-6-phosphate\ndehydrogenase) deficiency, a genetic condition that results in a shortage of the enzyme glucose-6-phosphate\ndehydrogenase, is the most common enzyme deficiency in humans. This enzyme, shown in Figure 12.21, is the\nrate-limiting enzyme for the metabolic pathway that supplies NADPH to cells (Figure 12.22).\n"]], ["block_2", [" FIGURE 12.21 \nGlucose-6-phosphate dehydrogenase is a rate-limiting enzyme for the metabolic pathway that\n"]], ["block_3", ["supplies NADPH to cells.\n"]], ["block_4", ["A disruption in this pathway can lead to reduced glutathione in red blood cells; once all glutathione is\nconsumed, enzymes and other proteins such as hemoglobin are susceptible to damage. For example,\nhemoglobin can be metabolized to bilirubin, which leads to jaundice, a condition that can become severe.\nPeople who suffer from G6PD deficiency must avoid certain foods and medicines containing chemicals that\ncan trigger damage their glutathione-deficient red blood cells.\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", ["amount of solar ultraviolet radiation\u2014 strongly linked to the prevalence of skin cancers\u2014reaches earth\u2019s\nsurface. The work of Molina and Rowland was instrumental in the adoption of the Montreal Protocol, an\ninternational treaty signed in 1987 that successfully began phasing out production of chemicals linked to\nozone destruction.\n"]], ["block_7", ["Molina and Rowland demonstrated that chlorine atoms from human-made chemicals can catalyze ozone\ndestruction in a process similar to that by which NO accelerates the depletion of ozone. Chlorine atoms are\ngenerated when chlorocarbons or chlorofluorocarbons\u2014once widely used as refrigerants and\npropellants\u2014are photochemically decomposed by ultraviolet light or react with hydroxyl radicals. A sample\nmechanism is shown here using methyl chloride:\n"]], ["block_8", ["Chlorine radicals break down ozone and are regenerated by the following catalytic cycle:\n"]], ["block_9", ["A single monatomic chlorine can break down thousands of ozone molecules. Luckily, the majority of\natmospheric chlorine exists as the catalytically inactive forms Cl2 and ClONO2.\n"]], ["block_10", ["Since receiving his portion of the Nobel Prize, Molina has continued his work in atmospheric chemistry at\nMIT.\n"]], ["block_11", ["HOW SCIENCES INTERCONNECT\n"]], ["block_12", [{"image_0": "651_0.png", "coords": [242, 481, 369, 579]}]]], "page_652": [["block_0", [" FIGURE 12.22 \nIn the mechanism for the pentose phosphate pathway, G6PD catalyzes the reaction that regulates\n"]], ["block_1", ["NADPH, a co-enzyme that regulates glutathione, an antioxidant that protects red blood cells and other cells from\noxidative damage.\n"]], ["block_2", [" Heterogeneous Catalysts \n"]], ["block_3", ["A heterogeneous catalyst is a catalyst that is present in a different phase (usually a solid) than the reactants.\nSuch catalysts generally function by furnishing an active surface upon which a reaction can occur. Gas and\nliquid phase reactions catalyzed by heterogeneous catalysts occur on the surface of the catalyst rather than\nwithin the gas or liquid phase.\n"]], ["block_4", ["Heterogeneous catalysis typically involves the following processes:\n"]], ["block_5", ["Figure 12.23 illustrates the steps of a mechanism for the reaction of compounds containing a carbon\u2013carbon\ndouble bond with hydrogen on a nickel catalyst. Nickel is the catalyst used in the hydrogenation of\npolyunsaturated fats and oils (which contain several carbon\u2013carbon double bonds) to produce saturated fats\nand oils (which contain only carbon\u2013carbon single bonds).\n"]], ["block_6", [" FIGURE 12.23 \nMechanism for the Ni-catalyzed reaction\n(a) Hydrogen is adsorbed on the\n"]], ["block_7", ["surface, breaking the H\u2013H bonds and forming Ni\u2013H bonds. (b) Ethylene is adsorbed on the surface, breaking the C\u2013C\n\u03c0-bond and forming Ni\u2013C bonds. (c) Atoms diffuse across the surface and form new C\u2013H bonds when they collide.\n(d) C2H6 molecules desorb from the Ni surface.\n"]], ["block_8", ["Many important chemical products are prepared via industrial processes that use heterogeneous catalysts,\nincluding ammonia, nitric acid, sulfuric acid, and methanol. Heterogeneous catalysts are also used in the\ncatalytic converters found on most gasoline-powered automobiles (Figure 12.24).\n"]], ["block_9", ["1.\nAdsorption of the reactant(s) onto the surface of the catalyst\n"]], ["block_10", ["2.\nActivation of the adsorbed reactant(s)\n"]], ["block_11", ["3.\nReaction of the adsorbed reactant(s)\n"]], ["block_12", ["4.\nDesorption of product(s) from the surface of the catalyst\n"]], ["block_13", [{"image_0": "652_0.png", "coords": [90, 57, 522, 211]}]], ["block_14", [{"image_1": "652_1.png", "coords": [130, 481, 481, 626]}]], ["block_15", [" 12.7 \u2022 Catalysis \n 639 \n"]]], "page_653": [["block_0", [" 640 \n 12 \u2022 Kinetics \n"]], ["block_1", ["The University of California at Davis\u2019 \u201cChemWiki\u201d provides a thorough explanation (http://openstax.org/l/\n16catconvert) of how catalytic converters work.\n"]], ["block_2", [" Enzyme Structure and Function \nThe study of enzymes is an important interconnection between biology and chemistry. Enzymes are usually\nproteins (polypeptides) that help to control the rate of chemical reactions between biologically important\n"]], ["block_3", [" Access for free at openstax.org \n"]], ["block_4", ["Chemistry in Everyday Life\n"]], ["block_5", [" Automobile Catalytic Converters \nScientists developed catalytic converters to reduce the amount of toxic emissions produced by burning\ngasoline in internal combustion engines. By utilizing a carefully selected blend of catalytically active\nmetals, it is possible to effect complete combustion of all carbon-containing compounds to carbon dioxide\nwhile also reducing the output of nitrogen oxides. This is particularly impressive when we consider that\none step involves adding more oxygen to the molecule and the other involves removing the oxygen (Figure\n12.24).\n"]], ["block_6", [" FIGURE 12.24 \nA catalytic converter allows for the combustion of all carbon-containing compounds to carbon\n"]], ["block_7", ["dioxide, while at the same time reducing the output of nitrogen oxide and other pollutants in emissions from\ngasoline-burning engines.\n"]], ["block_8", ["Most modern, three-way catalytic converters possess a surface impregnated with a platinum-rhodium\ncatalyst, which catalyzes the conversion of nitric oxide into dinitrogen and oxygen as well as the conversion\nof carbon monoxide and hydrocarbons such as octane into carbon dioxide and water vapor:\n"]], ["block_9", ["In order to be as efficient as possible, most catalytic converters are preheated by an electric heater. This\nensures that the metals in the catalyst are fully active even before the automobile exhaust is hot enough to\nmaintain appropriate reaction temperatures.\n"]], ["block_10", ["LINK TO LEARNING\n"]], ["block_11", ["HOW SCIENCES INTERCONNECT\n"]], ["block_12", [{"image_0": "653_0.png", "coords": [148, 180, 463, 372]}]]], "page_654": [["block_0", ["compounds, particularly those that are involved in cellular metabolism. Different classes of enzymes perform\na variety of functions, as shown in Table 12.3.\n"]], ["block_1", ["Enzyme molecules possess an active site, a part of the molecule with a shape that allows it to bond to a specific\nsubstrate (a reactant molecule), forming an enzyme-substrate complex as a reaction intermediate. There are\ntwo models that attempt to explain how this active site works. The most simplistic model is referred to as the\nlock-and-key hypothesis, which suggests that the molecular shapes of the active site and substrate are\ncomplementary, fitting together like a key in a lock. The induced fit hypothesis, on the other hand, suggests\nthat the enzyme molecule is flexible and changes shape to accommodate a bond with the substrate. This is not\nto suggest that an enzyme\u2019s active site is completely malleable, however. Both the lock-and-key model and the\ninduced fit model account for the fact that enzymes can only bind with specific substrates, since in general a\nparticular enzyme only catalyzes a particular reaction (Figure 12.25).\n"]], ["block_2", [" FIGURE 12.25 \n(a) According to the lock-and-key model, the shape of an enzyme\u2019s active site is a perfect fit for the\n"]], ["block_3", ["substrate. (b) According to the induced fit model, the active site is somewhat flexible, and can change shape in order\nto bond with the substrate.\n"]], ["block_4", ["The Royal Society of Chemistry (http://openstax.org/l/16enzymes) provides an excellent introduction to\nenzymes for students and teachers.\n"]], ["block_5", ["LINK TO LEARNING\n"]], ["block_6", [{"image_0": "654_0.png", "coords": [130, 446, 481, 600]}]], ["block_7", [" TABLE 12.3 \n"]], ["block_8", [" Class \n Function \n"]], ["block_9", ["oxidoreductases\nredox reactions\n"]], ["block_10", ["transferases\ntransfer of functional groups\n"]], ["block_11", ["hydrolases\nhydrolysis reactions\n"]], ["block_12", ["lyases\ngroup elimination to form double bonds\n"]], ["block_13", ["isomerases\nisomerization\n"]], ["block_14", ["ligases\nbond formation with ATP hydrolysis\n"]], ["block_15", ["Classes of Enzymes and Their Functions\n"]], ["block_16", [" 12.7 \u2022 Catalysis \n 641 \n"]]], "page_655": [["block_0", [" 642 \n 12 \u2022 Key Terms \n"]], ["block_1", [" Key Terms \n"]], ["block_2", [" activated complex \n(also, transition state) unstable\n"]], ["block_3", [" activation energy (E a ) \nminimum energy necessary\n"]], ["block_4", [" Arrhenius equation \nmathematical relationship\n"]], ["block_5", [" average rate \nrate of a chemical reaction computed\n"]], ["block_6", [" bimolecular reaction \nelementary reaction\n"]], ["block_7", [" catalyst \nsubstance that increases the rate of a\n"]], ["block_8", [" collision theory \nmodel that emphasizes the energy\n"]], ["block_9", ["elementary reaction\nreaction that takes place in a\n"]], ["block_10", [" frequency factor (A) \nproportionality constant in\n"]], ["block_11", [" half-life of a reaction (t l/2 ) \ntime required for half of\n"]], ["block_12", [" heterogeneous catalyst \ncatalyst present in a\n"]], ["block_13", [" homogeneous catalyst \ncatalyst present in the\n"]], ["block_14", [" initial rate \ninstantaneous rate of a chemical\n"]], ["block_15", [" instantaneous rate \nrate of a chemical reaction at\n"]], ["block_16", [" integrated rate law \nequation that relates the\n"]], ["block_17", [" Key Equations \n"]], ["block_18", [" Access for free at openstax.org \n"]], ["block_19", ["integrated rate law for zero-order reactions:\n"]], ["block_20", ["half-life for a zero-order reaction\n"]], ["block_21", ["integrated rate law for first-order reactions:\n"]], ["block_22", ["half-life for a first-order reaction\n"]], ["block_23", ["combination of reactant species formed during a\nchemical reaction\n"]], ["block_24", ["in order for a reaction to take place\n"]], ["block_25", ["between a reaction\u2019s rate constant, activation\nenergy, and temperature\n"]], ["block_26", ["as the ratio of a measured change in amount or\nconcentration of substance to the time interval\nover which the change occurred\n"]], ["block_27", ["involving two reactant species\n"]], ["block_28", ["reaction without itself being consumed by the\nreaction\n"]], ["block_29", ["and orientation of molecular collisions to explain\nand predict reaction kinetics\n"]], ["block_30", ["single step, precisely as depicted in its chemical\nequation\n"]], ["block_31", ["the Arrhenius equation, related to the relative\nnumber of collisions having an orientation\ncapable of leading to product formation\n"]], ["block_32", ["a given amount of reactant to be consumed\n"]], ["block_33", ["different phase from the reactants, furnishing a\nsurface at which a reaction can occur\n"]], ["block_34", ["same phase as the reactants\n"]], ["block_35", ["reaction at t = 0 s (immediately after the reaction\nhas begun)\n"]], ["block_36", ["any instant in time, determined by the slope of\nthe line tangential to a graph of concentration as a\nfunction of time\n"]], ["block_37", [" intermediate \nspecies produced in one step of a\n"]], ["block_38", [" method of initial rates \ncommon experimental\n"]], ["block_39", [" molecularity \nnumber of reactant species involved\n"]], ["block_40", [" overall reaction order \nsum of the reaction orders\n"]], ["block_41", [" rate constant (k) \nproportionality constant in a rate\n"]], ["block_42", [" rate expression \nmathematical representation\n"]], ["block_43", [" rate law \n(also, rate equation) (also, differential rate\n"]], ["block_44", [" rate of reaction \nmeasure of the speed at which a\n"]], ["block_45", [" rate-determining step \n(also, rate-limiting step)\n"]], ["block_46", [" reaction diagram \nused in chemical kinetics to\n"]], ["block_47", [" reaction mechanism \nstepwise sequence of\n"]], ["block_48", [" reaction order \nvalue of an exponent in a rate law\n"]], ["block_49", [" termolecular reaction \nelementary reaction\n"]], ["block_50", [" unimolecular reaction \nelementary reaction\n"]], ["block_51", ["concentration of a reactant to elapsed time of\nreaction\n"]], ["block_52", ["reaction mechanism and consumed in a\nsubsequent step\n"]], ["block_53", ["approach to determining rate laws that involves\nmeasuring reaction rates at varying initial\nreactant concentrations\n"]], ["block_54", ["in an elementary reaction\n"]], ["block_55", ["for each substance represented in the rate law\n"]], ["block_56", ["law\n"]], ["block_57", ["defining reaction rate as change in amount,\nconcentration, or pressure of reactant or product\nspecies per unit time\n"]], ["block_58", ["laws) mathematical equation showing the\ndependence of reaction rate on the rate constant\nand the concentration of one or more reactants\n"]], ["block_59", ["chemical reaction takes place\n"]], ["block_60", ["slowest elementary reaction in a reaction\nmechanism; determines the rate of the overall\nreaction\n"]], ["block_61", ["illustrate various properties of a reaction\n"]], ["block_62", ["elementary reactions by which a chemical change\ntakes place\n"]], ["block_63", ["(for example, zero order for 0, first order for 1,\nsecond order for 2, and so on)\n"]], ["block_64", ["involving three reactant species\n"]], ["block_65", ["involving a single reactant species\n"]]], "page_656": [["block_0", [" Summary \n"]], ["block_1", [" 12.1 Chemical Reaction Rates \n"]], ["block_2", ["The rate of a reaction can be expressed either in\nterms of the decrease in the amount of a reactant or\nthe increase in the amount of a product per unit\ntime. Relations between different rate expressions\nfor a given reaction are derived directly from the\nstoichiometric coefficients of the equation\nrepresenting the reaction.\n"]], ["block_3", [" 12.2 Factors Affecting Reaction Rates \n"]], ["block_4", ["The rate of a chemical reaction is affected by several\nparameters. Reactions involving two phases proceed\nmore rapidly when there is greater surface area\ncontact. If temperature or reactant concentration is\nincreased, the rate of a given reaction generally\nincreases as well. A catalyst can increase the rate of\na reaction by providing an alternative pathway with\na lower activation energy.\n"]], ["block_5", [" 12.3 Rate Laws \n"]], ["block_6", ["Rate laws (differential rate laws) provide a\nmathematical description of how changes in the\nconcentration of a substance affect the rate of a\nchemical reaction. Rate laws are determined\nexperimentally and cannot be predicted by reaction\nstoichiometry. The order of reaction describes how\nmuch a change in the concentration of each\nsubstance affects the overall rate, and the overall\norder of a reaction is the sum of the orders for each\nsubstance present in the reaction. Reaction orders\nare typically first order, second order, or zero order,\nbut fractional and even negative orders are possible.\n"]], ["block_7", [" 12.4 Integrated Rate Laws \n"]], ["block_8", ["Integrated rate laws are mathematically derived\nfrom differential rate laws, and they describe the\ntime dependence of reactant and product\nconcentrations.\n"]], ["block_9", ["The half-life of a reaction is the time required to\ndecrease the amount of a given reactant by one-half.\nA reaction\u2019s half-life varies with rate constant and,\n"]], ["block_10", ["integrated rate law for second-order reactions:\n"]], ["block_11", ["half-life for a second-order reaction\n"]], ["block_12", ["for some reaction orders, reactant concentration.\nThe half-life of a zero-order reaction decreases as\nthe initial concentration of the reactant in the\nreaction decreases. The half-life of a first-order\nreaction is independent of concentration, and the\nhalf-life of a second-order reaction decreases as the\nconcentration increases.\n"]], ["block_13", [" 12.5 Collision Theory \n"]], ["block_14", ["Chemical reactions typically require collisions\nbetween reactant species. These reactant collisions\nmust be of proper orientation and sufficient energy\nin order to result in product formation. Collision\ntheory provides a simple but effective explanation\nfor the effect of many experimental parameters on\nreaction rates. The Arrhenius equation describes the\nrelation between a reaction\u2019s rate constant,\nactivation energy, temperature, and dependence on\ncollision orientation.\n"]], ["block_15", [" 12.6 Reaction Mechanisms \n"]], ["block_16", ["The sequence of individual steps, or elementary\nreactions, by which reactants are converted into\nproducts during the course of a reaction is called the\nreaction mechanism. The molecularity of an\nelementary reaction is the number of reactant\nspecies involved, typically one (unimolecular), two\n(bimolecular), or, less commonly, three\n(termolecular). The overall rate of a reaction is\ndetermined by the rate of the slowest in its\nmechanism, called the rate-determining step.\nUnimolecular elementary reactions have first-order\nrate laws, while bimolecular elementary reactions\nhave second-order rate laws. By comparing the rate\nlaws derived from a reaction mechanism to that\ndetermined experimentally, the mechanism may be\ndeemed either incorrect or plausible.\n"]], ["block_17", [" 12.7 Catalysis \n"]], ["block_18", ["Catalysts affect the rate of a chemical reaction by\naltering its mechanism to provide a lower activation\nenergy. Catalysts can be homogenous (in the same\n"]], ["block_19", [" 12 \u2022 Summary \n 643 \n"]]], "page_657": [["block_0", [" 644 \n 12 \u2022 Exercises \n"]], ["block_1", ["phase as the reactants) or heterogeneous (a different\nphase than the reactants).\n"]], ["block_2", [" Exercises \n"]], ["block_3", [" 12.1 Chemical Reaction Rates \n"]], ["block_4", [" 4 . A study of the rate of dimerization of C4H6 gave the data shown in the table:\n"]], ["block_5", [" 5 . A study of the rate of the reaction represented as\ngave the following data:\n"]], ["block_6", [" 12.2 Factors Affecting Reaction Rates \n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [" 1 . What is the difference between average rate, initial rate, and instantaneous rate?\n 2 . Ozone decomposes to oxygen according to the equation\nWrite the equation that\n"]], ["block_9", [" 3 . In the nuclear industry, chlorine trifluoride is used to prepare uranium hexafluoride, a volatile compound\n"]], ["block_10", [" 6 . Consider the following reaction in aqueous solution:\n"]], ["block_11", [" 7 . Describe the effect of each of the following on the rate of the reaction of magnesium metal with a solution\n"]], ["block_12", [" 8 . Explain why an egg cooks more slowly in boiling water in Denver than in New York City. (Hint: Consider the\n"]], ["block_13", ["(a) Determine the average rate of dimerization between 0 s and 1600 s, and between 1600 s and 3200 s.\n(b) Estimate the instantaneous rate of dimerization at 3200 s from a graph of time versus [C4H6]. What are the\nunits of this rate?\n(c) Determine the average rate of formation of C8H12 at 1600 s and the instantaneous rate of formation at 3200\ns from the rates found in parts (a) and (b).\n"]], ["block_14", ["(a) Determine the average rate of disappearance of A between 0.0 s and 10.0 s, and between 10.0 s and 20.0 s.\n(b) Estimate the instantaneous rate of disappearance of A at 15.0 s from a graph of time versus [A]. What are\nthe units of this rate?\n(c) Use the rates found in parts (a) and (b) to determine the average rate of formation of B between 0.00 s and\n10.0 s, and the instantaneous rate of formation of B at 15.0 s.\n"]], ["block_15", ["relates the rate expressions for this reaction in terms of the disappearance of O3 and the formation of\noxygen.\n"]], ["block_16", ["of uranium used in the separation of uranium isotopes. Chlorine trifluoride is prepared by the reaction\n"]], ["block_17", ["terms of the disappearance of Cl2 and F2 and the formation of ClF3.\n"]], ["block_18", ["If the rate of disappearance of Br(aq) at a particular moment during the reaction is 3.5\n10mol Ls,\n"]], ["block_19", ["what is the rate of appearance of Br2(aq) at that moment?\n"]], ["block_20", ["of hydrochloric acid: the molarity of the hydrochloric acid, the temperature of the solution, and the size of\nthe pieces of magnesium.\n"]], ["block_21", ["effect of temperature on reaction rate and the effect of pressure on boiling point.)\n"]], ["block_22", ["Time (s)\n0.0\n5.0\n10.0\n15.0\n20.0\n25.0\n35.0\n"]], ["block_23", ["[A] (M)\n1.00\n0.775\n0.625\n0.465\n0.360\n0.285\n0.230\n"]], ["block_24", ["[C4H6] (M)\n1.00\n10\n5.04\n10\n3.37\n10\n2.53\n10\n2.08\n10\n"]], ["block_25", ["Time (s)\n0\n1600\n3200\n4800\n6200\n"]], ["block_26", ["Write the equation that relates the rate expressions for this reaction in\n"]]], "page_658": [["block_0", [" 10 . In the PhET Reactions & Rates (http://openstax.org/l/16PHETreaction) interactive, use the \u201cMany\n"]], ["block_1", [" 11 . In the PhET Reactions & Rates (http://openstax.org/l/16PHETreaction) interactive, on the Many Collisions\n"]], ["block_2", [" 12.3 Rate Laws \n"]], ["block_3", [" 12 . How do the rate of a reaction and its rate constant differ?\n 13 . Doubling the concentration of a reactant increases the rate of a reaction four times. With this knowledge,\n"]], ["block_4", [" 14 . Tripling the concentration of a reactant increases the rate of a reaction nine-fold. With this knowledge,\n"]], ["block_5", [" 15 . How will the rate of reaction change for the process:\nif the rate law\n"]], ["block_6", [" 16 . How will each of the following affect the rate of the reaction:\nif the\n"]], ["block_7", [" 17 . Regular flights of supersonic aircraft in the stratosphere are of concern because such aircraft produce\n"]], ["block_8", [" 9 . Go to the PhET Reactions & Rates (http://openstax.org/l/16PHETreaction) interactive. Use the Single\n"]], ["block_9", ["Collision tab to represent how the collision between monatomic oxygen (O) and carbon monoxide (CO)\nresults in the breaking of one bond and the formation of another. Pull back on the red plunger to release\nthe atom and observe the results. Then, click on \u201cReload Launcher\u201d and change to \u201cAngled shot\u201d to see the\ndifference.\n(a) What happens when the angle of the collision is changed?\n(b) Explain how this is relevant to rate of reaction.\n"]], ["block_10", ["Collisions\u201d tab to observe how multiple atoms and molecules interact under varying conditions. Select a\nmolecule to pump into the chamber. Set the initial temperature and select the current amounts of each\nreactant. Select \u201cShow bonds\u201d under Options. How is the rate of the reaction affected by concentration and\ntemperature?\n"]], ["block_11", ["tab, set up a simulation with 15 molecules of A and 10 molecules of BC. Select \u201cShow Bonds\u201d under\nOptions.\n(a) Leave the Initial Temperature at the default setting. Observe the reaction. Is the rate of reaction fast or\nslow?\n(b) Click \u201cPause\u201d and then \u201cReset All,\u201d and then enter 15 molecules of A and 10 molecules of BC once\nagain. Select \u201cShow Bonds\u201d under Options. This time, increase the initial temperature until, on the graph,\nthe total average energy line is completely above the potential energy curve. Describe what happens to the\nreaction.\n"]], ["block_12", ["answer the following questions:\n(a) What is the order of the reaction with respect to that reactant?\n(b) Tripling the concentration of a different reactant increases the rate of a reaction three times. What is\nthe order of the reaction with respect to that reactant?\n"]], ["block_13", ["answer the following questions:\n(a) What is the order of the reaction with respect to that reactant?\n(b) Increasing the concentration of a reactant by a factor of four increases the rate of a reaction four-fold.\nWhat is the order of the reaction with respect to that reactant?\n"]], ["block_14", ["for the reaction is\n(a) Decreasing the pressure of NO2 from 0.50 atm to 0.250 atm.\n(b) Increasing the concentration of CO from 0.01 M to 0.03 M.\n"]], ["block_15", ["rate law for the reaction is\n?\n"]], ["block_16", ["(a) Increasing the pressure of NO2 from 0.1 atm to 0.3 atm\n(b) Increasing the concentration of CO from 0.02 M to 0.06 M.\n"]], ["block_17", ["nitric oxide, NO, as a byproduct in the exhaust of their engines. Nitric oxide reacts with ozone, and it has\nbeen suggested that this could contribute to depletion of the ozone layer. The reaction\n"]], ["block_18", ["L/mol/s. What is the instantaneous rate of disappearance of NO when [NO] = 3.3\n10M and [O3] = 5.9\n"]], ["block_19", ["10M?\n"]], ["block_20", ["is first order with respect to both NO and O3 with a rate constant of 2.20\n10\n"]], ["block_21", [" 12 \u2022 Exercises \n 645 \n"]]], "page_659": [["block_0", [" 646 \n 12 \u2022 Exercises \n"]], ["block_1", [" 18 . Radioactive phosphorus is used in the study of biochemical reaction mechanisms because phosphorus\n"]], ["block_2", [" 19 . The rate constant for the radioactive decay of C is 1.21\n10year. The products of the decay are\n"]], ["block_3", [" 20 . The decomposition of acetaldehyde is a second order reaction with a rate constant of 4.71\n10L mol\n"]], ["block_4", [" 21 . Alcohol is removed from the bloodstream by a series of metabolic reactions. The first reaction produces\n"]], ["block_5", [" 22 . Under certain conditions the decomposition of ammonia on a metal surface gives the following data:\n"]], ["block_6", [" 23 . Nitrosyl chloride, NOCl, decomposes to NO and Cl2.\n"]], ["block_7", [" 24 . From the following data, determine the rate law, the rate constant, and the order with respect to A for the\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["atoms are components of many biochemical molecules. The location of the phosphorus (and the location\nof the molecule it is bound in) can be detected from the electrons (beta particles) it produces:\n"]], ["block_10", ["rate = 4.85\n10\n"]], ["block_11", ["What is the instantaneous rate of production of electrons in a sample with a phosphorus concentration of\n0.0033 M?\n"]], ["block_12", ["nitrogen atoms and electrons (beta particles):\n"]], ["block_13", ["What is the instantaneous rate of production of N atoms in a sample with a carbon-14 content of 6.5\n10M?\n"]], ["block_14", ["s. What is the instantaneous rate of decomposition of acetaldehyde in a solution with a concentration of\n5.55\n10M?\n"]], ["block_15", ["acetaldehyde; then other products are formed. The following data have been determined for the rate at which\nalcohol is removed from the blood of an average male, although individual rates can vary by 25\u201330%. Women\nmetabolize alcohol a little more slowly than men:\n"]], ["block_16", ["Determine the rate law, the rate constant, and the overall order for this reaction.\n"]], ["block_17", ["Determine the rate law, the rate constant, and the overall order for this reaction.\n"]], ["block_18", ["Determine the rate law, the rate constant, and the overall order for this reaction from the following data:\n"]], ["block_19", ["reaction\n"]], ["block_20", ["Rate (mol Lh)\n2.0\n10\n2.0\n10\n2.0\n10\n"]], ["block_21", ["Rate (mol Lh)\n1.5\n10\n1.5\n10\n1.5\n10\n"]], ["block_22", ["Rate (mol Lh)\n8.0\n10\n3.2\n10\n7.2\n10\n"]], ["block_23", ["Rate (mol Lh)\n3.80\n10\n1.52\n10\n3.42\n10\n"]], ["block_24", ["[C2H5OH] (M)\n4.4\n10\n3.3\n10\n2.2\n10\n"]], ["block_25", ["[NOCl] (M)\n0.10\n0.20\n0.30\n"]], ["block_26", ["[NH3] (M)\n1.0\n10\n2.0\n10\n3.0\n10\n"]], ["block_27", ["[A] (M)\n1.33\n10\n2.66\n10\n3.99\n10\n"]]], "page_660": [["block_0", [" 25 . Nitrogen monoxide reacts with chlorine according to the equation:\n"]], ["block_1", [" 26 . Hydrogen reacts with nitrogen monoxide to form dinitrogen monoxide (laughing gas) according to the\n"]], ["block_2", [" 27 . For the reaction\nthe following data were obtained at 30 \u00b0C:\n"]], ["block_3", [" 28 . For the reaction\nthe following data were obtained at 30 \u00b0C:\n"]], ["block_4", [" 29 . The rate constant for the first-order decomposition at 45 \u00b0C of dinitrogen pentoxide, N2O5, dissolved in\n"]], ["block_5", ["The following initial rates of reaction have been observed for certain reactant concentrations:\n"]], ["block_6", ["What is the rate law that describes the rate\u2019s dependence on the concentrations of NO and Cl2? What is the rate\nconstant? What are the orders with respect to each reactant?\n"]], ["block_7", ["equation:\nDetermine the rate law, the rate constant, and the orders with respect to each reactant from the following data:\n"]], ["block_8", ["(a) What is the order of the reaction with respect to [A], and what is the rate law?\n(b) What is the rate constant?\n"]], ["block_9", ["(a) What is the order of the reaction with respect to [Q], and what is the rate law?\n(b) What is the rate constant?\n"]], ["block_10", ["chloroform, CHCl3, is 6.2\n10min.\n"]], ["block_11", ["What is the rate of the reaction when [N2O5] = 0.40 M?\n"]], ["block_12", [" [NO] (mol/L) \n [Cl 2 ] (mol/L) \n Rate (mol L \u22121 h \u22121 ) \n"]], ["block_13", ["Rate (mol Ls)\n2.835\n10\n1.134\n10\n2.268\n10\n"]], ["block_14", ["Rate (mol Ls)\n4.17\n10\n9.99\n10\n2.44\n10\n"]], ["block_15", ["Rate (mol Ls)\n6.68\n10\n1.04\n10\n2.94\n10\n"]], ["block_16", ["[Q]initial (M)\n0.170\n0.212\n0.357\n"]], ["block_17", ["[NO] (M)\n0.30\n0.60\n0.60\n"]], ["block_18", ["[H2] (M)\n0.35\n0.35\n0.70\n"]], ["block_19", ["[A] (M)\n0.230\n0.356\n0.557\n"]], ["block_20", ["0.50\n0.50\n1.14\n"]], ["block_21", ["1.00\n0.50\n4.56\n"]], ["block_22", ["1.00\n1.00\n9.12\n"]], ["block_23", [" 12 \u2022 Exercises \n 647 \n"]]], "page_661": [["block_0", [" 648 \n 12 \u2022 Exercises \n"]], ["block_1", [" 30 . The annual production of HNO3 in 2013 was 60 million metric tons Most of that was prepared by the\n"]], ["block_2", [" 31 . The following data have been determined for the reaction:\n"]], ["block_3", [" 12.4 Integrated Rate Laws \n"]], ["block_4", [" 32 . Describe how graphical methods can be used to determine the order of a reaction and its rate constant\n"]], ["block_5", [" 33 . Use the data provided to graphically determine the order and rate constant of the following reaction:\n"]], ["block_6", [" 34 . Pure ozone decomposes slowly to oxygen,\nUse the data provided in a graphical method\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", ["following sequence of reactions, each run in a separate reaction vessel.\n(a)\n(b)\n(c)\nThe first reaction is run by burning ammonia in air over a platinum catalyst. This reaction is fast. The\nreaction in equation (c) is also fast. The second reaction limits the rate at which nitric acid can be\nprepared from ammonia. If equation (b) is second order in NO and first order in O2, what is the rate of\nformation of NO2 when the oxygen concentration is 0.50 M and the nitric oxide concentration is 0.75 M?\nThe rate constant for the reaction is 5.8\n10Lmols.\n"]], ["block_9", ["Determine the rate law and the rate constant for this reaction.\n"]], ["block_10", ["from a series of data that includes the concentration of A at varying times.\n"]], ["block_11", ["and determine the order and rate constant of the reaction.\n"]], ["block_12", ["Rate (mol Ls)\n3.05\n10\n6.20\n10\n1.83\n10\n"]], ["block_13", ["[SO2Cl2] (M)\n0.100\n0.0896\n0.0802\n0.0719\n"]], ["block_14", ["[SO2Cl2] (M)\n0.0577\n0.0517\n0.0415\n"]], ["block_15", ["Time (h)\n0\n2.0\n10\n7.6\n10\n1.00\n10\n"]], ["block_16", ["Time (h)\n1.23\n10\n1.43\n10\n1.70\n10\n"]], ["block_17", ["Time (s)\n0\n5.00\n10\n1.00\n10\n1.50\n10\n"]], ["block_18", ["Time (s)\n2.50\n10\n3.00\n10\n4.00\n10\n"]], ["block_19", ["[O3] (M)\n1.00\n10\n4.98\n10\n2.07\n10\n1.66\n10\n"]], ["block_20", ["[O3] (M)\n1.39\n10\n1.22\n10\n1.05\n10\n"]], ["block_21", ["(M)\n0.10\n0.20\n0.30\n"]], ["block_22", ["(M)\n0.050\n0.050\n0.010\n"]], ["block_23", [" 1 \n 2 \n 3 \n"]]], "page_662": [["block_0", [" 35 . From the given data, use a graphical method to determine the order and rate constant of the following\n"]], ["block_1", [" 36 . What is the half-life for the first-order decay of phosphorus-32?\nThe rate constant\n"]], ["block_2", [" 37 . What is the half-life for the first-order decay of carbon-14?\nThe rate constant for the\n"]], ["block_3", [" 38 . What is the half-life for the decomposition of NOCl when the concentration of NOCl is 0.15 M? The rate\n"]], ["block_4", [" 39 . What is the half-life for the decomposition of O3 when the concentration of O3 is 2.35\n10M? The rate\n"]], ["block_5", [" 40 . The reaction of compound A to give compounds C and D was found to be second-order in A. The rate\n"]], ["block_6", [" 41 . The half-life of a reaction of compound A to give compounds D and E is 8.50 min when the initial\n"]], ["block_7", [" 42 . Some bacteria are resistant to the antibiotic penicillin because they produce penicillinase, an enzyme with a\n"]], ["block_8", [" 43 . Both technetium-99 and thallium-201 are used to image heart muscle in patients with suspected heart\n"]], ["block_9", [" 44 . There are two molecules with the formula C3H6. Propene,\nis the monomer of the polymer\n"]], ["block_10", ["reaction:\n"]], ["block_11", ["for the decay is 4.85\n10day.\n"]], ["block_12", ["decay is 1.21\n10year.\n"]], ["block_13", ["constant for this second-order reaction is 8.0\n10L mols.\n"]], ["block_14", ["constant for this second-order reaction is 50.4 L molh.\n"]], ["block_15", ["constant for the reaction was determined to be 2.42 L mols. If the initial concentration is 0.500 mol/L,\nwhat is the value of t1/2?\n"]], ["block_16", ["concentration of A is 0.150 M. How long will it take for the concentration to drop to 0.0300 M if the\nreaction is (a) first order with respect to A or (b) second order with respect to A?\n"]], ["block_17", ["molecular weight of 3\n10g/mol that converts penicillin into inactive molecules. Although the kinetics of\n"]], ["block_18", ["enzyme-catalyzed reactions can be complex, at low concentrations this reaction can be described by a rate law\nthat is first order in the catalyst (penicillinase) and that also involves the concentration of penicillin. From the\nfollowing data: 1.0 L of a solution containing 0.15 \u00b5g (0.15\n10g) of penicillinase, determine the order of the\n"]], ["block_19", ["reaction with respect to penicillin and the value of the rate constant.\n"]], ["block_20", ["problems. The half-lives are 6 h and 73 h, respectively. What percent of the radioactivity would remain for\neach of the isotopes after 2 days (48 h)?\n"]], ["block_21", ["polypropylene, which is used for indoor-outdoor carpets. Cyclopropane is used as an anesthetic:\n"]], ["block_22", [{"image_0": "662_0.png", "coords": [91, 593, 189, 658]}]], ["block_23", ["When heated to 499 \u00b0C, cyclopropane rearranges (isomerizes) and forms propene with a rate constant of\n5.95\n10s. What is the half-life of this reaction? What fraction of the cyclopropane remains after 0.75\n"]], ["block_24", ["h at 499 \u00b0C?\n"]], ["block_25", [" [Penicillin] (M) \n Rate (mol L \u22121 min \u22121 ) \n"]], ["block_26", ["Time (s)\n5.0\n10.0\n15.0\n20.0\n25.0\n30.0\n35.0\n40.0\n"]], ["block_27", ["[X] (M)\n0.0990\n0.0497\n0.0332\n0.0249\n0.0200\n0.0166\n0.0143\n0.0125\n"]], ["block_28", ["2.0\n10\n1.0\n10\n"]], ["block_29", ["3.0\n10\n1.5\n10\n"]], ["block_30", ["4.0\n10\n2.0\n10\n"]], ["block_31", [" 12 \u2022 Exercises \n 649 \n"]]], "page_663": [["block_0", [" 650 \n 12 \u2022 Exercises \n"]], ["block_1", [" 45 . Fluorine-18 is a radioactive isotope that decays by positron emission to form oxygen-18 with a half-life of\n"]], ["block_2", [" 46 . Suppose that the half-life of steroids taken by an athlete is 42 days. Assuming that the steroids biodegrade\n"]], ["block_3", [" 47 . Recently, the skeleton of King Richard III was found under a parking lot in England. If tissue samples from\n"]], ["block_4", [" 48 . Nitroglycerine is an extremely sensitive explosive. In a series of carefully controlled experiments, samples of\n"]], ["block_5", [" 49 . For the past 10 years, the unsaturated hydrocarbon 1,3-butadiene\nhas ranked\n"]], ["block_6", [" 12.5 Collision Theory \n"]], ["block_7", [" 50 . Chemical reactions occur when reactants collide. What are two factors that may prevent a collision from\n"]], ["block_8", [" 51 . When every collision between reactants leads to a reaction, what determines the rate at which the\n"]], ["block_9", [" 52 . What is the activation energy of a reaction, and how is this energy related to the activated complex of the\n"]], ["block_10", [" 53 . Account for the relationship between the rate of a reaction and its activation energy.\n 54 . Describe how graphical methods can be used to determine the activation energy of a reaction from a\n"]], ["block_11", [" 55 . How does an increase in temperature affect rate of reaction? Explain this effect in terms of the collision\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["109.7 min. (A positron is a particle with the mass of an electron and a single unit of positive charge; the\nequation is\nPhysicians use F to study the brain by injecting a quantity of fluoro-\n"]], ["block_14", ["substituted glucose into the blood of a patient. The glucose accumulates in the regions where the brain is\nactive and needs nourishment.\n(a) What is the rate constant for the decomposition of fluorine-18?\n(b) If a sample of glucose containing radioactive fluorine-18 is injected into the blood, what percent of the\nradioactivity will remain after 5.59 h?\n(c) How long does it take for 99.99% of the F to decay?\n"]], ["block_15", ["by a first-order process, how long would it take for\nof the initial dose to remain in the athlete\u2019s body?\n"]], ["block_16", ["the skeleton contain about 93.79% of the carbon-14 expected in living tissue, what year did King Richard\nIII die? The half-life for carbon-14 is 5730 years.\n"]], ["block_17", ["the explosive were heated to 160 \u00b0C and their first-order decomposition studied. Determine the average rate\nconstants for each experiment using the following data:\n"]], ["block_18", ["38th among the top 50 industrial chemicals. It is used primarily for the manufacture of synthetic rubber.\nAn isomer exists also as cyclobutene:\n"]], ["block_19", [{"image_0": "663_0.png", "coords": [91, 441, 170, 497]}]], ["block_20", ["The isomerization of cyclobutene to butadiene is first-order and the rate constant has been measured as\n2.0\n10sat 150 \u00b0C in a 0.53-L flask. Determine the partial pressure of cyclobutene and its\n"]], ["block_21", ["concentration after 30.0 minutes if an isomerization reaction is carried out at 150 \u00b0C with an initial\npressure of 55 torr.\n"]], ["block_22", ["producing a chemical reaction?\n"]], ["block_23", ["reaction occurs?\n"]], ["block_24", ["reaction?\n"]], ["block_25", ["series of data that includes the rate of reaction at varying temperatures.\n"]], ["block_26", ["theory of the reaction rate.\n"]], ["block_27", ["[C3H5N3O9]\n"]], ["block_28", ["Decomposed\n52.0\n52.9\n53.2\n53.9\n34.6\n35.9\n36.0\n35.4\n"]], ["block_29", ["Initial\n"]], ["block_30", ["t (s)\n300\n300\n300\n300\n180\n180\n180\n180\n"]], ["block_31", ["(M)\n"]], ["block_32", ["%\n"]], ["block_33", ["4.88\n3.52\n2.29\n1.81\n5.33\n4.05\n2.95\n1.72\n"]]], "page_664": [["block_0", [" 56 . The rate of a certain reaction doubles for every 10 \u00b0C rise in temperature.\n"]], ["block_1", [" 57 . In an experiment, a sample of NaClO3 was 90% decomposed in 48 min. Approximately how long would\n"]], ["block_2", [" 58 . The rate constant at 325 \u00b0C for the decomposition reaction\nis 6.1\n10s, and the\n"]], ["block_3", [" 59 . The rate constant for the decomposition of acetaldehyde, CH3CHO, to methane, CH4, and carbon\n"]], ["block_4", [" 60 . An elevated level of the enzyme alkaline phosphatase (ALP) in human serum is an indication of possible\n"]], ["block_5", [" 61 . In terms of collision theory, to which of the following is the rate of a chemical reaction proportional?\n"]], ["block_6", [" 62 . Hydrogen iodide, HI, decomposes in the gas phase to produce hydrogen, H2, and iodine, I2. The value of the\n"]], ["block_7", [" 63 . The element Co exists in two oxidation states, Co(II) and Co(III), and the ions form many complexes. The rate at\n"]], ["block_8", ["(a) How much faster does the reaction proceed at 45 \u00b0C than at 25 \u00b0C?\n(b) How much faster does the reaction proceed at 95 \u00b0C than at 25 \u00b0C?\n"]], ["block_9", ["this decomposition have taken if the sample had been heated 20 \u00b0C higher? (Hint: Assume the rate\ndoubles for each 10 \u00b0C rise in temperature.)\n"]], ["block_10", ["activation energy is 261 kJ per mole of C4H8. Determine the frequency factor for the reaction.\n"]], ["block_11", ["monoxide, CO, in the gas phase is 1.1\n10L molsat 703 K and 4.95 L molsat 865 K. Determine\n"]], ["block_12", ["the activation energy for this decomposition.\n"]], ["block_13", ["liver or bone disorder. The level of serum ALP is so low that it is very difficult to measure directly.\nHowever, ALP catalyzes a number of reactions, and its relative concentration can be determined by\nmeasuring the rate of one of these reactions under controlled conditions. One such reaction is the\nconversion of p-nitrophenyl phosphate (PNPP) to p-nitrophenoxide ion (PNP) and phosphate ion. Control\nof temperature during the test is very important; the rate of the reaction increases 1.47 times if the\ntemperature changes from 30 \u00b0C to 37 \u00b0C. What is the activation energy for the ALP\u2013catalyzed conversion\nof PNPP to PNP and phosphate?\n"]], ["block_14", ["(a) the change in free energy per second\n(b) the change in temperature per second\n(c) the number of collisions per second\n(d) the number of product molecules\n"]], ["block_15", ["rate constant, k, for the reaction was measured at several different temperatures and the data are shown here:\n"]], ["block_16", ["What is the value of the activation energy (in kJ/mol) for this reaction?\n"]], ["block_17", ["which one of the complexes of Co(III) was reduced by Fe(II) in water was measured. Determine the activation\nenergy of the reaction from the following data:\n"]], ["block_18", [" T (K) \n k (s \u22121 ) \n"]], ["block_19", [" Temperature (K) \n k (L mol \u22121 s \u22121 ) \n"]], ["block_20", ["555\n6.23\n10\n"]], ["block_21", ["575\n2.42\n10\n"]], ["block_22", ["645\n1.44\n10\n"]], ["block_23", ["700\n2.01\n10\n"]], ["block_24", ["293\n0.054\n"]], ["block_25", ["298\n0.100\n"]], ["block_26", [" 12 \u2022 Exercises \n 651 \n"]]], "page_665": [["block_0", [" 652 \n 12 \u2022 Exercises \n"]], ["block_1", [" 64 . The hydrolysis of the sugar sucrose to the sugars glucose and fructose,\n"]], ["block_2", [" 65 . Use the PhET Reactions & Rates interactive simulation (http://openstax.org/l/16PHETreaction) to simulate\n"]], ["block_3", [" 66 . Use the PhET Reactions & Rates interactive simulation (http://openstax.org/l/16PHETreaction) to simulate\n"]], ["block_4", [" 12.6 Reaction Mechanisms \n"]], ["block_5", [" 67 . Why are elementary reactions involving three or more reactants very uncommon?\n 68 . In general, can we predict the effect of doubling the concentration of A on the rate of the overall reaction\n"]], ["block_6", [" 69 . Define these terms:\n"]], ["block_7", [" 70 . What is the rate law for the elementary termolecular reaction\nFor\n"]], ["block_8", [" 71 . Given the following reactions and the corresponding rate laws, in which of the reactions might the\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["follows a first-order rate law for the disappearance of sucrose: rate = k[C12H22O11] (The products of the\nreaction, glucose and fructose, have the same molecular formulas but differ in the arrangement of the\natoms in their molecules.)\n(a) In neutral solution, k = 2.1\n10sat 27 \u00b0C and 8.5\n10sat 37 \u00b0C. Determine the activation\n"]], ["block_11", ["energy, the frequency factor, and the rate constant for this equation at 47 \u00b0C (assuming the kinetics\nremain consistent with the Arrhenius equation at this temperature).\n(b) When a solution of sucrose with an initial concentration of 0.150 M reaches equilibrium, the\nconcentration of sucrose is 1.65\n10M. How long will it take the solution to reach equilibrium at 27 \u00b0C\n"]], ["block_12", ["in the absence of a catalyst? Because the concentration of sucrose at equilibrium is so low, assume that the\nreaction is irreversible.\n(c) Why does assuming that the reaction is irreversible simplify the calculation in part (b)?\n"]], ["block_13", ["a system. On the \u201cSingle collision\u201d tab of the simulation applet, enable the \u201cEnergy view\u201d by clicking the\n\u201c+\u201d icon. Select the first\nreaction (A is yellow, B is purple, and C is navy blue). Using\n"]], ["block_14", ["the \u201cstraight shot\u201d default option, try launching the A atom with varying amounts of energy. What changes\nwhen the Total Energy line at launch is below the transition state of the Potential Energy line? Why? What\nhappens when it is above the transition state? Why?\n"]], ["block_15", ["a system. On the \u201cSingle collision\u201d tab of the simulation applet, enable the \u201cEnergy view\u201d by clicking the\n\u201c+\u201d icon. Select the first\nreaction (A is yellow, B is purple, and C is navy blue). Using\n"]], ["block_16", ["the \u201cangled shot\u201d option, try launching the A atom with varying angles, but with more Total energy than\nthe transition state. What happens when the A atom hits the BC molecule from different directions? Why?\n"]], ["block_17", ["(a) unimolecular reaction\n(b) bimolecular reaction\n(c) elementary reaction\n(d) overall reaction\n"]], ["block_18", ["elementary reaction and the overall reaction be the same?\n"]], ["block_19", ["? Can we predict the effect if the reaction is known to be an elementary reaction?\n"]]], "page_666": [["block_0", [" 72 . Write the rate law for each of the following elementary reactions:\n"]], ["block_1", [" 73 . Nitrogen monoxide, NO, reacts with hydrogen, H2, according to the following equation:\n"]], ["block_2", [" 74 . Experiments were conducted to study the rate of the reaction represented by this equation.\n"]], ["block_3", [" 75 . The reaction of CO with Cl2 gives phosgene (COCl2), a nerve gas that was used in World War I. Use the\n"]], ["block_4", [" 12.7 Catalysis \n"]], ["block_5", [" 76 . Account for the increase in reaction rate brought about by a catalyst.\n"]], ["block_6", ["2 This question is taken from the Chemistry Advanced Placement Examination and is used with the permission of the Educational\nTesting Service.\n"]], ["block_7", ["(a)\n(b)\n(c)\n(d)\n(e)\n"]], ["block_8", ["What would the rate law be if the mechanism for this reaction were:\n"]], ["block_9", ["Initial concentrations and rates of reaction are given here.\n"]], ["block_10", ["Consider the following questions:\n(a) Determine the order for each of the reactants, NO and H2, from the data given and show your reasoning.\n(b) Write the overall rate law for the reaction.\n(c) Calculate the value of the rate constant, k, for the reaction. Include units.\n(d) For experiment 2, calculate the concentration of NO remaining when exactly one-half of the original\namount of H2 had been consumed.\n(e) The following sequence of elementary steps is a proposed mechanism for the reaction.\nStep 1:\nStep 2:\nStep 3:\nBased on the data presented, which of these is the rate determining step? Show that the mechanism is\nconsistent with the observed rate law for the reaction and the overall stoichiometry of the reaction.\n"]], ["block_11", ["mechanism shown here to complete the following exercises:\n"]], ["block_12", ["(a) Write the overall reaction.\n(b) Identify all intermediates.\n(c) Write the rate law for each elementary reaction.\n(d) Write the overall rate law expression.\n"]], ["block_13", [" Experiment \n Initial Concentration \n [NO] (mol L \u22121 ) \n"]], ["block_14", ["1\n0.0060\n0.0010\n1.8\n10\n"]], ["block_15", ["2\n0.0060\n0.0020\n3.6\n10\n"]], ["block_16", ["3\n0.0010\n0.0060\n0.30\n10\n"]], ["block_17", ["4\n0.0020\n0.0060\n1.2\n10\n"]], ["block_18", ["(fast, k1 represents the forward rate constant, k\u22121 the reverse rate constant)\n"]], ["block_19", ["(slow, k2 the rate constant)\n"]], ["block_20", ["(fast, k3 the rate constant)\n"]], ["block_21", [" Initial Concentration, \n [H 2 ] (mol L \u22121 min \u22121 ) \n"]], ["block_22", [" Initial Rate of Formation \n of N 2 (mol L \u22121 min \u22121 ) \n"]], ["block_23", [" 12 \u2022 Exercises \n 653 \n"]]], "page_667": [["block_0", [" 654 \n 12 \u2022 Exercises \n"]], ["block_1", [" 77 . Compare the functions of homogeneous and heterogeneous catalysts.\n 78 . Consider this scenario and answer the following questions: Chlorine atoms resulting from decomposition\n"]], ["block_2", [" 79 . For each of the following pairs of reaction diagrams, identify which of the pair is catalyzed:\n"]], ["block_3", [" Access for free at openstax.org \n"]], ["block_4", ["of chlorofluoromethanes, such as CCl2F2, catalyze the decomposition of ozone in the atmosphere. One\nsimplified mechanism for the decomposition is:\n"]], ["block_5", ["(a) Explain why chlorine atoms are catalysts in the gas-phase transformation:\n"]], ["block_6", ["(b) Nitric oxide is also involved in the decomposition of ozone by the mechanism:\n"]], ["block_7", ["Is NO a catalyst for the decomposition? Explain your answer.\n"]], ["block_8", ["(a)\n"]], ["block_9", [{"image_0": "667_0.png", "coords": [91, 324, 523, 468]}]], ["block_10", ["(b)\n"]], ["block_11", [{"image_1": "667_1.png", "coords": [91, 483, 523, 637]}]]], "page_668": [["block_0", [" 80 . For each of the following pairs of reaction diagrams, identify which of the pairs is catalyzed:\n"]], ["block_1", [" 81 . For each of the following reaction diagrams, estimate the activation energy (Ea) of the reaction:\n"]], ["block_2", ["(a)\n"]], ["block_3", [{"image_0": "668_0.png", "coords": [91, 82, 523, 236]}]], ["block_4", ["(b)\n"]], ["block_5", [{"image_1": "668_1.png", "coords": [91, 252, 523, 406]}]], ["block_6", ["(a)\n"]], ["block_7", [{"image_2": "668_2.png", "coords": [91, 434, 325, 554]}]], ["block_8", ["(b)\n"]], ["block_9", [{"image_3": "668_3.png", "coords": [91, 569, 325, 689]}]], ["block_10", [" 12 \u2022 Exercises \n 655 \n"]]], "page_669": [["block_0", [" 656 \n 12 \u2022 Exercises \n"]], ["block_1", [" 82 . For each of the following reaction diagrams, estimate the activation energy (Ea) of the reaction:\n"]], ["block_2", [" 83 . Assuming the diagrams in Exercise 12.81 represent different mechanisms for the same reaction, which of\n"]], ["block_3", [" 84 . Consider the similarities and differences in the two reaction diagrams shown in Exercise 12.82. Do these\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", ["(a)\n"]], ["block_6", [{"image_0": "669_0.png", "coords": [91, 82, 325, 222]}]], ["block_7", ["(b)\n"]], ["block_8", [{"image_1": "669_1.png", "coords": [91, 238, 325, 378]}]], ["block_9", ["the reactions has the faster rate?\n"]], ["block_10", ["diagrams represent two different overall reactions, or do they represent the same overall reaction taking\nplace by two different mechanisms? Explain your answer.\n"]]], "page_670": [["block_0", ["CHAPTER 13\nFundamental Equilibrium Concepts\n"]], ["block_1", [{"image_0": "670_0.png", "coords": [72, 104, 622, 358]}]], ["block_2", [" Figure 13.1 \nTransport of carbon dioxide in the body involves several reversible chemical reactions, including\n"]], ["block_3", ["hydrolysis and acid ionization (among others).\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 13.1 Chemical Equilibria \n 13.2 Equilibrium Constants \n 13.3 Shifting Equilibria: Le Ch\u00e2telier\u2019s Principle \n 13.4 Equilibrium Calculations \n"]], ["block_6", [" INTRODUCTION \n"]], ["block_7", ["too hot, they enter the surf to swim and cool off. As the swimmers tire, they return to the beach to rest. If the\nrate at which sunbathers enter the surf were to equal the rate at which swimmers return to the sand, then the\nnumbers (though not the identities) of sunbathers and swimmers would remain constant. This scenario\nillustrates a dynamic phenomenon known as equilibrium, in which opposing processes occur at equal rates.\nChemical and physical processes are subject to this phenomenon; these processes are at equilibrium when the\nforward and reverse reaction rates are equal. Equilibrium systems are pervasive in nature; the various\nreactions involving carbon dioxide dissolved in blood are examples (see Figure 13.1). This chapter provides a\nthorough introduction to the essential aspects of chemical equilibria.\n"]], ["block_8", [" 13.1 Chemical Equilibria \n"]], ["block_9", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_10", ["The convention for writing chemical equations involves placing reactant formulas on the left side of a reaction\n"]], ["block_11", ["\u2022\nDescribe the nature of equilibrium systems\n"]], ["block_12", ["\u2022\nExplain the dynamic nature of a chemical equilibrium\n"]], ["block_13", ["Imagine a beach populated with sunbathers and swimmers. As those basking in the sun get\n"]]], "page_671": [["block_0", [" 658 \n 13 \u2022 Fundamental Equilibrium Concepts \n"]], ["block_1", ["arrow and product formulas on the right side. By this convention, and the definitions of \u201creactant\u201d and\n\u201cproduct,\u201d a chemical equation represents the reaction in question as proceeding from left to right. Reversible \n reactions , however, may proceed in both forward (left to right) and reverse (right to left) directions. When the\nrates of the forward and reverse reactions are equal, the concentrations of the reactant and product species\nremain constant over time and the system is at equilibrium . The relative concentrations of reactants and\nproducts in equilibrium systems vary greatly; some systems contain mostly products at equilibrium, some\ncontain mostly reactants, and some contain appreciable amounts of both.\n"]], ["block_2", ["Figure 13.2 illustrates fundamental equilibrium concepts using the reversible decomposition of colorless\ndinitrogen tetroxide to yield brown nitrogen dioxide, an elementary reaction described by the equation:\n"]], ["block_3", ["Note that a special double arrow is used to emphasize the reversible nature of the reaction.\n"]], ["block_4", [" FIGURE 13.2 \n(a) A sealed tube containing colorless N2O4 darkens as it decomposes to yield brown NO2. (b)\n"]], ["block_5", ["Changes in concentration over time as the decomposition reaction achieves equilibrium. (c) At equilibrium, the\nforward and reverse reaction rates are equal.\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [{"image_0": "671_0.png", "coords": [189, 218, 423, 681]}]]], "page_672": [["block_0", ["As the reaction begins (t = 0), the concentration of the N2O4 reactant is finite and that of the NO2 product is\nzero, so the forward reaction proceeds at a finite rate while the reverse reaction rate is zero. As time passes,\nN2O4 is consumed and its concentration falls, while NO2 is produced and its concentration increases (Figure\n13.2 b ). The decreasing concentration of the reactant slows the forward reaction rate, and the increasing\nproduct concentration speeds the reverse reaction rate (Figure 13.2 c ). This process continues until the\nforward and reverse reaction rates become equal, at which time the reaction has reached equilibrium, as\ncharacterized by constant concentrations of its reactants and products (shaded areas of Figure 13.2 b and\nFigure 13.2 c ). It\u2019s important to emphasize that chemical equilibria are dynamic; a reaction at equilibrium has\nnot \u201cstopped,\u201d but is proceeding in the forward and reverse directions at the same rate. This dynamic nature is\nessential to understanding equilibrium behavior as discussed in this and subsequent chapters of the text.\n"]], ["block_1", ["For this elementary process, rate laws for the forward and reverse reactions may be derived directly from the\nreaction stoichiometry:\n"]], ["block_2", [" FIGURE 13.3 \nA two-person juggling act illustrates the dynamic aspect of chemical equilibria. Each person is\n"]], ["block_3", ["throwing and catching clubs at the same rate, and each holds a (approximately) constant number of clubs.\n"]], ["block_4", ["Physical changes, such as phase transitions, are also reversible and may establish equilibria. This concept was\nintroduced in another chapter of this text through discussion of the vapor pressure of a condensed phase\n(liquid or solid). As one example, consider the vaporization of bromine:\n"]], ["block_5", ["When liquid bromine is added to an otherwise empty container and the container is sealed, the forward\nprocess depicted above (vaporization) will commence and continue at a roughly constant rate as long as the\nexposed surface area of the liquid and its temperature remain constant. As increasing amounts of gaseous\nbromine are produced, the rate of the reverse process (condensation) will increase until it equals the rate of\nvaporization and equilibrium is established. A photograph showing this phase transition equilibrium is\nprovided in Figure 13.4.\n"]], ["block_6", [{"image_0": "672_0.png", "coords": [189, 258, 423, 432]}]], ["block_7", [" 13.1 \u2022 Chemical Equilibria \n 659 \n"]]], "page_673": [["block_0", [" 660 \n 13 \u2022 Fundamental Equilibrium Concepts \n"]], ["block_1", ["Note that the reaction quotient equations above are a simplification of more rigorous expressions that use\nrelative values for concentrations and pressures rather than absolute values. These relative concentration and\npressure values are dimensionless (they have no units); consequently, so are the reaction quotients. For\npurposes of this introductory text, it will suffice to use the simplified equations and to disregard units when\ncomputing Q. In most cases, this will introduce only modest errors in calculations involving reaction quotients.\n"]], ["block_2", [" FIGURE 13.4 \nA sealed tube containing an equilibrium mixture of liquid and gaseous bromine. (credit:\n"]], ["block_3", ["http://images-of-elements.com/bromine.php)\n"]], ["block_4", [" 13.2 Equilibrium Constants \n"]], ["block_5", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_6", ["The status of a reversible reaction is conveniently assessed by evaluating its reaction quotient (Q) . For a\nreversible reaction described by\n"]], ["block_7", ["the reaction quotient is derived directly from the stoichiometry of the balanced equation as\n"]], ["block_8", ["where the subscript c denotes the use of molar concentrations in the expression. If the reactants and products\nare gaseous, a reaction quotient may be similarly derived using partial pressures:\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["\u2022\nDerive reaction quotients from chemical equations representing homogeneous and heterogeneous reactions\n"]], ["block_11", ["\u2022\nCalculate values of reaction quotients and equilibrium constants, using concentrations and pressures\n"]], ["block_12", ["\u2022\nRelate the magnitude of an equilibrium constant to properties of the chemical system\n"]], ["block_13", [{"image_0": "673_0.png", "coords": [189, 57, 423, 333]}]]], "page_674": [["block_0", [" Writing Reaction Quotient Expressions \n"]], ["block_1", ["Write the concentration-based reaction quotient expression for each of the following reactions:\n"]], ["block_2", ["(a)\n"]], ["block_3", ["(b)\n"]], ["block_4", ["(c)\n"]], ["block_5", [" Solution \n"]], ["block_6", ["(a)\n"]], ["block_7", ["(b)\n"]], ["block_8", ["(c)\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["Write the concentration-based reaction quotient expression for each of the following reactions:\n"]], ["block_11", ["(a)\n"]], ["block_12", ["(b)\n"]], ["block_13", ["(c)\n"]], ["block_14", [" Answer: \n"]], ["block_15", ["(a)\n(b)\n(c)\n"]], ["block_16", ["EXAMPLE 13.1\n"]], ["block_17", [" 13.2 \u2022 Equilibrium Constants \n 661 \n"]]], "page_675": [["block_0", [" 662 \n 13 \u2022 Fundamental Equilibrium Concepts \n"]], ["block_1", [{"image_0": "675_0.png", "coords": [72, 57, 540, 459]}]], ["block_2", [" FIGURE 13.5 \nChanges in concentrations and Qc for a chemical equilibrium achieved beginning with (a) a mixture of\n"]], ["block_3", ["reactants only and (b) products only.\n"]], ["block_4", ["The numerical value of Q varies as a reaction proceeds towards equilibrium; therefore, it can serve as a useful\nindicator of the reaction\u2019s status. To illustrate this point, consider the oxidation of sulfur dioxide:\n"]], ["block_5", ["Two different experimental scenarios are depicted in Figure 13.5, one in which this reaction is initiated with a\nmixture of reactants only, SO2 and O2, and another that begins with only product, SO3. For the reaction that\nbegins with a mixture of reactants only, Q is initially equal to zero:\n"]], ["block_6", ["As the reaction proceeds toward equilibrium in the forward direction, reactant concentrations decrease (as\ndoes the denominator of Qc), product concentration increases (as does the numerator of Qc), and the reaction\nquotient consequently increases. When equilibrium is achieved, the concentrations of reactants and product\nremain constant, as does the value of Qc.\n"]], ["block_7", ["If the reaction begins with only product present, the value of Qc is initially undefined (immeasurably large, or\ninfinite):\n"]], ["block_8", [" Access for free at openstax.org \n"]]], "page_676": [["block_0", ["M, and [SO3] = 1.1 M. What is the value of the equilibrium constant, Kc?\n"]], ["block_1", [" Answer: \nKc = 4.3\n"]], ["block_2", ["In this case, the reaction proceeds toward equilibrium in the reverse direction. The product concentration and\nthe numerator of Qc decrease with time, the reactant concentrations and the denominator of Qc increase, and\nthe reaction quotient consequently decreases until it becomes constant at equilibrium.\n"]], ["block_3", ["The constant value of Q exhibited by a system at equilibrium is called the equilibrium constant, K :\n"]], ["block_4", ["Comparison of the data plots in Figure 13.5 shows that both experimental scenarios resulted in the same value\nfor the equilibrium constant. This is a general observation for all equilibrium systems, known as the law of \n mass action : At a given temperature, the reaction quotient for a system at equilibrium is constant.\n"]], ["block_5", [" Evaluating a Reaction Quotient \n"]], ["block_6", ["Gaseous nitrogen dioxide forms dinitrogen tetroxide according to this equation:\n"]], ["block_7", ["When 0.10 mol NO2 is added to a 1.0-L flask at 25 \u00b0C, the concentration changes so that at equilibrium, [NO2] =\n0.016 M and [N2O4] = 0.042 M.\n"]], ["block_8", ["(a) What is the value of the reaction quotient before any reaction occurs?\n"]], ["block_9", ["(b) What is the value of the equilibrium constant for the reaction?\n"]], ["block_10", [" Solution \n"]], ["block_11", ["As for all equilibrium calculations in this text, use the simplified equations for Q and K and disregard any\nconcentration or pressure units, as noted previously in this section.\n"]], ["block_12", ["(a) Before any product is formed,\nand [N2O4] = 0 M. Thus,\n"]], ["block_13", ["(b) At equilibrium,\nThe equilibrium constant is 1.6\n10.\n"]], ["block_14", [" Check Your Learning \n"]], ["block_15", ["For the reaction\nthe concentrations at equilibrium are [SO2] = 0.90 M, [O2] = 0.35\n"]], ["block_16", ["By its definition, the magnitude of an equilibrium constant explicitly reflects the composition of a reaction\nmixture at equilibrium, and it may be interpreted with regard to the extent of the forward reaction. A reaction\nexhibiting a large K will reach equilibrium when most of the reactant has been converted to product, whereas a\nsmall K indicates the reaction achieves equilibrium after very little reactant has been converted. It\u2019s important\nto keep in mind that the magnitude of K does not indicate how rapidly or slowly equilibrium will be reached.\nSome equilibria are established so quickly as to be nearly instantaneous, and others so slowly that no\nperceptible change is observed over the course of days, years, or longer.\n"]], ["block_17", ["The equilibrium constant for a reaction can be used to predict the behavior of mixtures containing its\nreactants and/or products. As demonstrated by the sulfur dioxide oxidation process described above, a\nchemical reaction will proceed in whatever direction is necessary to achieve equilibrium. Comparing Q to K for\n"]], ["block_18", ["EXAMPLE 13.2\n"]], ["block_19", [" 13.2 \u2022 Equilibrium Constants \n 663 \n"]]], "page_677": [["block_0", [" 664 \n 13 \u2022 Fundamental Equilibrium Concepts \n"]], ["block_1", ["an equilibrium system of interest allows prediction of what reaction (forward or reverse), if any, will occur.\n"]], ["block_2", ["To further illustrate this important point, consider the reversible reaction shown below:\n"]], ["block_3", ["The bar charts in Figure 13.6 represent changes in reactant and product concentrations for three different\nreaction mixtures. The reaction quotients for mixtures 1 and 3 are initially lesser than the reaction\u2019s\nequilibrium constant, so each of these mixtures will experience a net forward reaction to achieve equilibrium.\nThe reaction quotient for mixture 2 is initially greater than the equilibrium constant, so this mixture will\nproceed in the reverse direction until equilibrium is established.\n"]], ["block_4", [{"image_0": "677_0.png", "coords": [72, 181, 540, 403]}]], ["block_5", [" FIGURE 13.6 \nCompositions of three mixtures before (Qc \u2260 Kc) and after (Qc = Kc) equilibrium is established for the\n"]], ["block_6", ["reaction\n"]], ["block_7", [" Predicting the Direction of Reaction \n"]], ["block_8", ["Given here are the starting concentrations of reactants and products for three experiments involving this\nreaction:\n"]], ["block_9", ["Determine in which direction the reaction proceeds as it goes to equilibrium in each of the three experiments\nshown.\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["EXAMPLE 13.3\n"]], ["block_12", [" Reactants/Products \n Experiment 1 \n Experiment 2 \n Experiment 3 \n"]], ["block_13", ["[CO]i\n0.020 M\n0.011 M\n0.0094 M\n"]], ["block_14", ["[H2O]i\n0.020 M\n0.0011 M\n0.0025 M\n"]], ["block_15", ["[CO2]i\n0.0040 M\n0.037 M\n0.0015 M\n"]], ["block_16", ["[H2]i\n0.0040 M\n0.046 M\n0.0076 M\n"]]], "page_678": [["block_0", ["Qc < Kc (0.040 < 0.64)\n"]], ["block_1", ["Qc > Kc (140 > 0.64)\n"]], ["block_2", ["Qc < Kc (0.48 < 0.64)\n"]], ["block_3", [" Solution \n"]], ["block_4", ["Experiment 1:\n"]], ["block_5", ["The reaction will proceed in the forward direction.\n"]], ["block_6", ["Experiment 2:\n"]], ["block_7", ["The reaction will proceed in the reverse direction.\n"]], ["block_8", ["Experiment 3:\n"]], ["block_9", ["The reaction will proceed in the forward direction.\n"]], ["block_10", [" Check Your Learning \n"]], ["block_11", ["Calculate the reaction quotient and determine the direction in which each of the following reactions will\nproceed to reach equilibrium.\n"]], ["block_12", ["(a) A 1.00-L flask containing 0.0500 mol of NO(g), 0.0155 mol of Cl2(g), and 0.500 mol of NOCl:\n"]], ["block_13", ["(b) A 5.0-L flask containing 17 g of NH3, 14 g of N2, and 12 g of H2:\n"]], ["block_14", ["(c) A 2.00-L flask containing 230 g of SO3(g):\n"]], ["block_15", [" Answer: \n(a) Qc = 6.45\n10, forward. (b) Qc = 0.23, reverse. (c) Qc = 0, forward.\n"]], ["block_16", [" Homogeneous Equilibria \n"]], ["block_17", ["A homogeneous equilibrium is one in which all reactants and products (and any catalysts, if applicable) are\npresent in the same phase. By this definition, homogeneous equilibria take place in solutions. These solutions\nare most commonly either liquid or gaseous phases, as shown by the examples below:\n"]], ["block_18", ["These examples all involve aqueous solutions, those in which water functions as the solvent. In the last two\n"]], ["block_19", [" 13.2 \u2022 Equilibrium Constants \n 665 \n"]]], "page_679": [["block_0", [" 666 \n 13 \u2022 Fundamental Equilibrium Concepts \n"]], ["block_1", ["examples, water also functions as a reactant, but its concentration is not included in the reaction quotient. The\nreason for this omission is related to the more rigorous form of the Q (or K) expression mentioned previously\nin this chapter, in which relative concentrations for liquids and solids are equal to 1 and needn\u2019t be included.\nConsequently, reaction quotients include concentration or pressure terms only for gaseous and solute species.\n"]], ["block_2", ["The equilibria below all involve gas-phase solutions:\n"]], ["block_3", ["For gas-phase solutions, the equilibrium constant may be expressed in terms of either the molar\nconcentrations (Kc) or partial pressures (Kp) of the reactants and products. A relation between these two K\nvalues may be simply derived from the ideal gas equation and the definition of molarity:\n"]], ["block_4", ["where P is partial pressure, V is volume, n is molar amount, R is the gas constant, T is temperature, and M is\nmolar concentration.\n"]], ["block_5", ["For the gas-phase reaction\n"]], ["block_6", ["And so, the relationship between Kc and KP is\n"]], ["block_7", ["where \u0394n is the difference in the molar amounts of product and reactant gases, in this case:\n"]], ["block_8", [" Calculation of K P \nWrite the equations relating Kc to KP for each of the following reactions:\n"]], ["block_9", ["(a)\n"]], ["block_10", ["(b)\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["EXAMPLE 13.4\n"]]], "page_680": [["block_0", ["(a) \u0394n = (2) \u2212 (1) = 1\nKP = Kc (RT)= Kc (RT)= Kc (RT)\n"]], ["block_1", ["(b) \u0394n = (2) \u2212 (2) = 0\nKP = Kc (RT)= Kc (RT)= Kc\n"]], ["block_2", ["KP = Kc (RT)= Kc (RT)=\n"]], ["block_3", ["(c)\n"]], ["block_4", ["(d) Kc is equal to 0.28 for the following reaction at 900 \u00b0C:\n"]], ["block_5", ["What is KP at this temperature?\n"]], ["block_6", [" Solution \n"]], ["block_7", ["(c) \u0394n = (2) \u2212 (1 + 3) = \u22122\n"]], ["block_8", ["(d) KP = Kc (RT)= (0.28)[(0.0821)(1173)]= 3.0\n10\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["Write the equations relating Kc to KP for each of the following reactions:\n"]], ["block_11", ["(a)\n"]], ["block_12", ["(b)\n"]], ["block_13", ["(c)\n"]], ["block_14", ["(d) At 227 \u00b0C, the following reaction has Kc = 0.0952:\n"]], ["block_15", ["What would be the value of KP at this temperature?\n"]], ["block_16", [" Answer: \n(a) KP = Kc (RT); (b) KP = Kc (RT); (c) KP = Kc (RT); (d) 160 or 1.6\n10\n"]], ["block_17", [" Heterogeneous Equilibria \n"]], ["block_18", ["A heterogeneous equilibrium involves reactants and products in two or more different phases, as illustrated\nby the following examples:\n"]], ["block_19", ["Again, note that concentration terms are only included for gaseous and solute species, as discussed previously.\n"]], ["block_20", ["Two of the above examples include terms for gaseous species only in their equilibrium constants, and so Kp\nexpressions may also be written:\n"]], ["block_21", [" 13.2 \u2022 Equilibrium Constants \n 667 \n"]]], "page_681": [["block_0", [" 668 \n 13 \u2022 Fundamental Equilibrium Concepts \n"]], ["block_1", [" Coupled Equilibria \n"]], ["block_2", ["The equilibrium systems discussed so far have all been relatively simple, involving just single reversible\nreactions. Many systems, however, involve two or more coupled equilibrium reactions, those which have in\ncommon one or more reactant or product species. Since the law of mass action allows for a straightforward\nderivation of equilibrium constant expressions from balanced chemical equations, the K value for a system\ninvolving coupled equilibria can be related to the K values of the individual reactions. Three basic\nmanipulations are involved in this approach, as described below.\n"]], ["block_3", ["1. Changing the direction of a chemical equation essentially swaps the identities of \u201creactants\u201d and \u201cproducts,\u201d\nand so the equilibrium constant for the reversed equation is simply the reciprocal of that for the forward\nequation.\n"]], ["block_4", ["2. Changing the stoichiometric coefficients in an equation by some factor x results in an exponential change in\nthe equilibrium constant by that same factor:\n"]], ["block_5", ["3. Adding two or more equilibrium equations together yields an overall equation whose equilibrium constant is\nthe mathematical product of the individual reaction\u2019s K values:\n"]], ["block_6", ["The net reaction for these coupled equilibria is obtained by summing the two equilibrium equations and\ncanceling any redundancies:\n"]], ["block_7", ["Comparing the equilibrium constant for the net reaction to those for the two coupled equilibrium reactions\nreveals the following relationship:\n"]], ["block_8", [" Access for free at openstax.org \n"]]], "page_682": [["block_0", ["A system at equilibrium is in a state of dynamic balance, with forward and reverse reactions taking place at\nequal rates. If an equilibrium system is subjected to a change in conditions that affects these reaction rates\ndifferently (a stress), then the rates are no longer equal and the system is not at equilibrium. The system will\nsubsequently experience a net reaction in the direction of greater rate (a shift) that will re-establish the\nequilibrium. This phenomenon is summarized by Le Ch\u00e2telier\u2019s principle : if an equilibrium system is\nstressed, the system will experience a shift in response to the stress that re-establishes equilibrium.\n"]], ["block_1", ["Example 13.5 demonstrates the use of this strategy in describing coupled equilibrium processes.\n"]], ["block_2", [" Equilibrium Constants for Coupled Reactions \n"]], ["block_3", ["A mixture containing nitrogen, hydrogen, and iodine established the following equilibrium at 400 \u00b0C:\n"]], ["block_4", ["Use the information below to calculate Kc for this reaction.\n"]], ["block_5", [" Solution \n"]], ["block_6", ["The equilibrium equation of interest and its K value may be derived from the equations for the two coupled\nreactions as follows.\n"]], ["block_7", ["Reverse the first coupled reaction equation:\n"]], ["block_8", ["Multiply the second coupled reaction by 3:\n"]], ["block_9", ["Finally, add the two revised equations:\n"]], ["block_10", [" Check Your Learning \n"]], ["block_11", ["Use the provided information to calculate Kc for the following reaction at 550 \u00b0C:\n"]], ["block_12", [" Answer: \nKc = 0.14\n"]], ["block_13", [" 13.3 Shifting Equilibria: Le Ch\u00e2telier\u2019s Principle \n"]], ["block_14", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_15", ["\u2022\nDescribe the ways in which an equilibrium system can be stressed\n"]], ["block_16", ["\u2022\nPredict the response of a stressed equilibrium using Le Ch\u00e2telier\u2019s principle\n"]], ["block_17", ["EXAMPLE 13.5\n"]], ["block_18", ["\u2009\n"]], ["block_19", [" 13.3 \u2022 Shifting Equilibria: Le Ch\u00e2telier\u2019s Principle \n 669 \n"]]], "page_683": [["block_0", [" 670 \n 13 \u2022 Fundamental Equilibrium Concepts \n"]], ["block_1", ["The system will experience a temporary net reaction in the forward direction to re-establish equilibrium (the\nequilibrium will shift right). This same shift will result if some product HI is removed from the system, which\ndecreases the rate of the reverse reaction, again resulting in the same imbalance in rates.\n"]], ["block_2", ["If reactant is added (increasing the denominator of the reaction quotient) or product is removed (decreasing\nthe numerator), then Qc < Kc and the equilibrium will shift right. Note that the three different ways of inducing\nthis stress result in three different changes in the composition of the equilibrium mixture. If H2 is added, the\nright shift will consume I2 and produce HI as equilibrium is re-established, yielding a mixture with a greater\nconcentrations of H2 and HI and a lesser concentration of I2 than was present before. If I2 is added, the new\nequilibrium mixture will have greater concentrations of I2 and HI and a lesser concentration of H2. Finally, if HI\nis removed, the concentrations of all three species will be lower when equilibrium is reestablished. Despite\nthese differences in composition, the value of the equilibrium constant will be the same after the stress as it\nwas before (per the law of mass action). The same logic may be applied for stresses involving removing\nreactants or adding product, in which case Qc > Kc and the equilibrium will shift left.\n"]], ["block_3", ["Reaction rates are affected primarily by concentrations, as described by the reaction\u2019s rate law, and\ntemperature, as described by the Arrhenius equation. Consequently, changes in concentration and\ntemperature are the two stresses that can shift an equilibrium.\n"]], ["block_4", [" Effect of a Change in Concentration \n"]], ["block_5", ["If an equilibrium system is subjected to a change in the concentration of a reactant or product species, the rate\nof either the forward or the reverse reaction will change. As an example, consider the equilibrium reaction\n"]], ["block_6", ["The rate laws for the forward and reverse reactions are\n"]], ["block_7", ["When this system is at equilibrium, the forward and reverse reaction rates are equal.\n"]], ["block_8", ["If the system is stressed by adding reactant, either H2 or I2, the resulting increase in concentration causes the\nrate of the forward reaction to increase, exceeding that of the reverse reaction:\n"]], ["block_9", ["The same logic can be used to explain the left shift that results from either removing reactant or adding\nproduct to an equilibrium system. These stresses both result in an increased rate for the reverse reaction\n"]], ["block_10", ["and a temporary net reaction in the reverse direction to re-establish equilibrium.\n"]], ["block_11", ["As an alternative to this kinetic interpretation, the effect of changes in concentration on equilibria can be\nrationalized in terms of reaction quotients. When the system is at equilibrium,\n"]], ["block_12", ["For gas-phase equilibria such as this one, some additional perspectives on changing the concentrations of\nreactants and products are worthy of mention. The partial pressure P of an ideal gas is proportional to its\nmolar concentration M,\n"]], ["block_13", ["and so changes in the partial pressures of any reactant or product are essentially changes in concentrations\nand thus yield the same effects on equilibria. Aside from adding or removing reactant or product, the\n"]], ["block_14", [" Access for free at openstax.org \n"]]], "page_684": [["block_0", ["pressures (concentrations) of species in a gas-phase equilibrium can also be changed by changing the volume\noccupied by the system. Since all species of a gas-phase equilibrium occupy the same volume, a given change\nin volume will cause the same change in concentration for both reactants and products. In order to discern\nwhat shift, if any, this type of stress will induce the stoichiometry of the reaction must be considered.\n"]], ["block_1", ["At equilibrium, the reaction H2(g) + I2(g) \u21cc 2HI(g) is described by the reaction quotient\n"]], ["block_2", ["If the volume occupied by an equilibrium mixture of these species is decreased by a factor of 3, the partial\npressures of all three species will be increased by a factor of 3:\n"]], ["block_3", ["And so, changing the volume of this gas-phase equilibrium mixture does not result in a shift of the\nequilibrium.\n"]], ["block_4", ["A similar treatment of a different system, 2NO2(g) \u21cc 2 NO(g) + O2(g), however, yields a different result:\n"]], ["block_5", ["In this case, the change in volume results in a reaction quotient greater than the equilibrium constant, and so\nthe equilibrium will shift left.\n"]], ["block_6", ["These results illustrate the relationship between the stoichiometry of a gas-phase equilibrium and the effect of\na volume-induced pressure (concentration) change. If the total molar amounts of reactants and products are\nequal, as in the first example, a change in volume does not shift the equilibrium. If the molar amounts of\nreactants and products are different, a change in volume will shift the equilibrium in a direction that better\n\u201caccommodates\u201d the volume change. In the second example, two moles of reactant (NO2) yield three moles of\nproduct (2NO + O2), and so decreasing the system volume causes the equilibrium to shift left since the reverse\nreaction produces less gas (2 mol) than the forward reaction (3 mol). Conversely, increasing the volume of this\nequilibrium system would result in a shift towards products.\n"]], ["block_7", ["Check out this link (http://openstax.org/l/16equichange) to see a dramatic visual demonstration of how\nequilibrium changes with pressure changes.\n"]], ["block_8", ["Chemistry in Everyday Life\n"]], ["block_9", [" Equilibrium and Soft Drinks \nThe connection between chemistry and carbonated soft drinks goes back to 1767, when Joseph Priestley\n(1733\u20131804) developed a method of infusing water with carbon dioxide to make carbonated water.\nPriestley\u2019s approach involved production of carbon dioxide by reacting oil of vitriol (sulfuric acid) with\n"]], ["block_10", ["LINK TO LEARNING\n"]], ["block_11", [" 13.3 \u2022 Shifting Equilibria: Le Ch\u00e2telier\u2019s Principle \n 671 \n"]]], "page_685": [["block_0", [" 672 \n 13 \u2022 Fundamental Equilibrium Concepts \n"]], ["block_1", [" Effect of a Change in Temperature \n"]], ["block_2", ["Consistent with the law of mass action, an equilibrium stressed by a change in concentration will shift to re-\nestablish equilibrium without any change in the value of the equilibrium constant, K. When an equilibrium\nshifts in response to a temperature change, however, it is re-established with a different relative composition\n"]], ["block_3", [" Access for free at openstax.org \n"]], ["block_4", ["chalk (calcium carbonate).\n"]], ["block_5", ["The carbon dioxide was then dissolved in water, reacting to produce hydrogen carbonate, a weak acid that\nsubsequently ionized to yield bicarbonate and hydrogen ions:\n"]], ["block_6", ["These same equilibrium reactions are the basis of today\u2019s soft-drink carbonation process. Beverages are\nexposed to a high pressure of gaseous carbon dioxide during the process to shift the first equilibrium above\nto the right, resulting in desirably high concentrations of dissolved carbon dioxide and, per similar shifts in\nthe other two equilibria, its hydrolysis and ionization products. A bottle or can is then nearly filled with the\ncarbonated beverage, leaving a relatively small volume of air in the container above the beverage surface\n(the headspace) before it is sealed. The pressure of carbon dioxide in the container headspace is very low\nimmediately after sealing, but it rises as the dissolution equilibrium is re-established by shifting to the left.\nSince the volume of the beverage is significantly greater than the volume of the headspace, only a relatively\nsmall amount of dissolved carbon dioxide is lost to the headspace.\n"]], ["block_7", ["When a carbonated beverage container is opened, a hissing sound is heard as pressurized CO2 escapes\nfrom the headspace. This causes the dissolution equilibrium to shift left, resulting in a decrease in the\nconcentration of dissolved CO2 and subsequent left-shifts of the hydrolysis and ionization equilibria.\nFortunately for the consumer, the dissolution equilibrium is usually re-established slowly, and so the\nbeverage may be enjoyed while its dissolved carbon dioxide concentration remains palatably high. Once\nthe equilibria are re-established, the CO2(aq) concentration will be significantly lowered, and the beverage\nacquires a characteristic taste referred to as \u201cflat.\u201d\n"]], ["block_8", [" FIGURE 13.7 \nOpening a soft-drink bottle lowers the CO2 pressure above the beverage, shifting the dissolution\n"]], ["block_9", ["equilibrium and releasing dissolved CO2 from the beverage. (credit: modification of work by \u201cD Coetzee\u201d/Flickr)\n"]], ["block_10", [{"image_0": "685_0.png", "coords": [130, 370, 481, 611]}]]], "page_686": [["block_0", ["To discern the effect of catalysis on an equilibrium system, consider the reaction diagram for a simple one-\nstep (elementary) reaction shown in Figure 13.8. The lowered transition state energy of the catalyzed reaction\nresults in lowered activation energies for both the forward and the reverse reactions. Consequently, both\nforward and reverse reactions are accelerated, and equilibrium is achieved more quickly but without a change\nin the equilibrium constant.\n"]], ["block_1", ["that exhibits a different value for the equilibrium constant.\n"]], ["block_2", ["To understand this phenomenon, consider the elementary reaction\n"]], ["block_3", ["Since this is an elementary reaction, the rates laws for the forward and reverse may be derived directly from\nthe balanced equation\u2019s stoichiometry:\n"]], ["block_4", ["When the system is at equilibrium,\n"]], ["block_5", ["Substituting the rate laws into this equality and rearranging gives\n"]], ["block_6", ["The equilibrium constant is seen to be a mathematical function of the rate constants for the forward and\nreverse reactions. Since the rate constants vary with temperature as described by the Arrhenius equation, is\nstands to reason that the equilibrium constant will likewise vary with temperature (assuming the rate\nconstants are affected to different extents by the temperature change). For more complex reactions involving\nmultistep reaction mechanisms, a similar but more complex mathematical relation exists between the\nequilibrium constant and the rate constants of the steps in the mechanism. Regardless of how complex the\nreaction may be, the temperature-dependence of its equilibrium constant persists.\n"]], ["block_7", ["Predicting the shift an equilibrium will experience in response to a change in temperature is most\nconveniently accomplished by considering the enthalpy change of the reaction. For example, the\ndecomposition of dinitrogen tetroxide is an endothermic (heat-consuming) process:\n"]], ["block_8", ["For purposes of applying Le Chatelier\u2019s principle, heat (q) may be viewed as a reactant:\n"]], ["block_9", ["Raising the temperature of the system is akin to increasing the amount of a reactant, and so the equilibrium\nwill shift to the right. Lowering the system temperature will likewise cause the equilibrium to shift left. For\nexothermic processes, heat is viewed as a product of the reaction and so the opposite temperature dependence\nis observed.\n"]], ["block_10", [" Effect of a Catalyst \n"]], ["block_11", ["The kinetics chapter of this text identifies a catalyst as a substance that enables a reaction to proceed via a\ndifferent mechanism with an accelerated rate. The catalyzed reaction mechanism involves a lower energy\ntransition state than the uncatalyzed reaction, resulting in a lower activation energy, Ea, and a correspondingly\ngreater rate constant.\n"]], ["block_12", [" 13.3 \u2022 Shifting Equilibria: Le Ch\u00e2telier\u2019s Principle \n 673 \n"]]], "page_687": [["block_0", [" 674 \n 13 \u2022 Fundamental Equilibrium Concepts \n"]], ["block_1", [" FIGURE 13.8 \nReaction diagrams for an elementary process in the absence (red) and presence (blue) of a catalyst.\n"]], ["block_2", ["The presence of catalyst lowers the activation energies of both the forward and reverse reactions but does not affect\nthe value of the equilibrium constant.\n"]], ["block_3", ["An interesting case study highlighting these equilibrium concepts is the industrial production of ammonia,\nNH3. This substance is among the \u201ctop 10\u201d industrial chemicals with regard to production, with roughly two\nbillion pounds produced annually in the US. Ammonia is used as a chemical feedstock to synthesize a wide\nrange of commercially useful compounds, including fertilizers, plastics, dyes, and explosives.\n"]], ["block_4", ["Most industrial production of ammonia uses the Haber-Bosch process based on the following equilibrium\nreaction:\n"]], ["block_5", ["The traits of this reaction present challenges to its use in an efficient industrial process. The equilibrium\nconstant is relatively small (Kp on the order of 10at 25 \u00b0C), meaning very little ammonia is present in an\nequilibrium mixture. Also, the rate of this reaction is relatively slow at low temperatures. To raise the yield of\nammonia, the industrial process is designed to operate under conditions favoring product formation:\n"]], ["block_6", ["A diagram illustrating a typical industrial setup for production of ammonia via the Haber-Bosch process is\nshown in Figure 13.9.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", ["\u2022\nHigh pressures (concentrations) of reactants are used, ~150\u2212250 atm, to shift the equilibrium right,\nfavoring product formation.\n"]], ["block_9", ["\u2022\nAmmonia is continually removed (collected) from the equilibrium mixture during the process, lowering its\nconcentration and also shifting the equilibrium right.\n"]], ["block_10", ["\u2022\nAlthough low temperatures favor product formation for this exothermic process, the reaction rate at low\ntemperatures is inefficiently slow. A catalyst is used to accelerate the reaction to reasonable rates at\nrelatively moderate temperatures (400\u2212500 \u00b0C).\n"]], ["block_11", [{"image_0": "687_0.png", "coords": [189, 57, 423, 280]}]]], "page_688": [["block_0", [{"image_0": "688_0.png", "coords": [72, 57, 540, 361]}]], ["block_1", [" FIGURE 13.9 \nThe figure shows a typical industrial setup for the commercial production of ammonia by the Haber-\n"]], ["block_2", ["Bosch process. The process operates under conditions that stress the chemical equilibrium to favor product\nformation.\n"]], ["block_3", [" 13.4 Equilibrium Calculations \n"]], ["block_4", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_5", ["Having covered the essential concepts of chemical equilibria in the preceding sections of this chapter, this final\nsection will demonstrate the more practical aspect of using these concepts and appropriate mathematical\nstrategies to perform various equilibrium calculations. These types of computations are essential to many\nareas of science and technology\u2014for example, in the formulation and dosing of pharmaceutical products. After\na drug is ingested or injected, it is typically involved in several chemical equilibria that affect its ultimate\nconcentration in the body system of interest. Knowledge of the quantitative aspects of these equilibria is\nrequired to compute a dosage amount that will solicit the desired therapeutic effect.\n"]], ["block_6", ["Many of the useful equilibrium calculations that will be demonstrated here require terms representing\nchanges in reactant and product concentrations. These terms are derived from the stoichiometry of the\nreaction, as illustrated by decomposition of ammonia:\n"]], ["block_7", ["As shown earlier in this chapter, this equilibrium may be established within a sealed container that initially\ncontains either NH3 only, or a mixture of any two of the three chemical species involved in the equilibrium.\nRegardless of its initial composition, a reaction mixture will show the same relationships between changes in\nthe concentrations of the three species involved, as dictated by the reaction stoichiometry (see also the related\ncontent on expressing reaction rates in the chapter on kinetics). For example, if the nitrogen concentration\nincreases by an amount x:\n"]], ["block_8", ["\u2022\nIdentify the changes in concentration or pressure that occur for chemical species in equilibrium systems\n"]], ["block_9", ["\u2022\nCalculate equilibrium concentrations or pressures and equilibrium constants, using various algebraic\napproaches\n"]], ["block_10", [" 13.4 \u2022 Equilibrium Calculations \n 675 \n"]]], "page_689": [["block_0", [" 676 \n 13 \u2022 Fundamental Equilibrium Concepts \n"]], ["block_1", ["the corresponding changes in the other species concentrations are\n"]], ["block_2", ["where the negative sign indicates a decrease in concentration.\n"]], ["block_3", [" Determining Relative Changes in Concentration \n"]], ["block_4", ["Derive the missing terms representing concentration changes for each of the following reactions.\n"]], ["block_5", ["(a)\n"]], ["block_6", ["(b)\n"]], ["block_7", ["(c)\n"]], ["block_8", [" Solution \n"]], ["block_9", ["(a)\n"]], ["block_10", ["(b)\n"]], ["block_11", ["(c)\n"]], ["block_12", [" Check Your Learning \n"]], ["block_13", ["Complete the changes in concentrations for each of the following reactions:\n"]], ["block_14", ["(a)\n"]], ["block_15", ["(b)\n"]], ["block_16", ["(c)\n"]], ["block_17", [" Answer: \n(a) 2x, x, \u22122x; (b) x, \u22122x; (c) 4x, 7x, \u22124x, \u22126x or \u22124x, \u22127x, 4x, 6x\n"]], ["block_18", [" Calculation of an Equilibrium Constant \n"]], ["block_19", ["The equilibrium constant for a reaction is calculated from the equilibrium concentrations (or pressures) of its\nreactants and products. If these concentrations are known, the calculation simply involves their substitution\ninto the K expression, as was illustrated by Example 13.2. A slightly more challenging example is provided\nnext, in which the reaction stoichiometry is used to derive equilibrium concentrations from the information\n"]], ["block_20", [" Access for free at openstax.org \n"]], ["block_21", ["EXAMPLE 13.6\n"]], ["block_22", ["\u2009\n"]]], "page_690": [["block_0", ["provided. The basic strategy of this computation is helpful for many types of equilibrium computations and\nrelies on the use of terms for the reactant and product concentrations initially present, for how they change as\nthe reaction proceeds, and for what they are when the system reaches equilibrium. The acronym ICE is\ncommonly used to refer to this mathematical approach, and the concentrations terms are usually gathered in a\ntabular format called an ICE table.\n"]], ["block_1", [" Calculation of an Equilibrium Constant \n"]], ["block_2", ["Iodine molecules react reversibly with iodide ions to produce triiodide ions.\n"]], ["block_3", ["If a solution with the concentrations of I2 and Iboth equal to 1.000\n10M before reaction gives an\n"]], ["block_4", ["equilibrium concentration of I2 of 6.61\n10M, what is the equilibrium constant for the reaction?\n"]], ["block_5", [" Solution \n"]], ["block_6", ["To calculate the equilibrium constants, equilibrium concentrations are needed for all the reactants and\nproducts:\n"]], ["block_7", ["Provided are the initial concentrations of the reactants and the equilibrium concentration of the product. Use\nthis information to derive terms for the equilibrium concentrations of the reactants, presenting all the\ninformation in an ICE table.\n"]], ["block_8", [{"image_0": "690_0.png", "coords": [72, 366, 423, 481]}]], ["block_9", ["At equilibrium the concentration of I2 is 6.61\n10M so that\n"]], ["block_10", ["The ICE table may now be updated with numerical values for all its concentrations:\n"]], ["block_11", [{"image_1": "690_1.png", "coords": [72, 576, 423, 671]}]], ["block_12", ["Finally, substitute the equilibrium concentrations into the K expression and solve:\n"]], ["block_13", ["EXAMPLE 13.7\n"]], ["block_14", [" 13.4 \u2022 Equilibrium Calculations \n 677 \n"]]], "page_691": [["block_0", [" 678 \n 13 \u2022 Fundamental Equilibrium Concepts \n"]], ["block_1", [" Answer: \nKc = 4\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["Ethanol and acetic acid react and form water and ethyl acetate, the solvent responsible for the odor of some\nnail polish removers.\n"]], ["block_4", ["When 1 mol each of C2H5OH and CH3CO2H are allowed to react in 1 L of the solvent dioxane, equilibrium is\nestablished when\nmol of each of the reactants remains. Calculate the equilibrium constant for the reaction.\n"]], ["block_5", ["(Note: Water is a solute in this reaction.)\n"]], ["block_6", [" Calculation of a Missing Equilibrium Concentration \n"]], ["block_7", ["When the equilibrium constant and all but one equilibrium concentration are provided, the other equilibrium\nconcentration(s) may be calculated. A computation of this sort is illustrated in the next example exercise.\n"]], ["block_8", [" Calculation of a Missing Equilibrium Concentration \n"]], ["block_9", ["Nitrogen oxides are air pollutants produced by the reaction of nitrogen and oxygen at high temperatures. At\n2000 \u00b0C, the value of the Kc for the reaction,\nis 4.1\n10. Calculate the equilibrium\n"]], ["block_10", ["concentration of NO(g) in air at 1 atm pressure and 2000 \u00b0C. The equilibrium concentrations of N2 and O2 at\nthis pressure and temperature are 0.036 M and 0.0089 M, respectively.\n"]], ["block_11", [" Solution \n"]], ["block_12", ["Substitute the provided quantities into the equilibrium constant expression and solve for [NO]:\n"]], ["block_13", ["Thus [NO] is 3.6\n10mol/L at equilibrium under these conditions.\n"]], ["block_14", ["To confirm this result, it may be used along with the provided equilibrium concentrations to calculate a value\nfor K:\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["EXAMPLE 13.8\n"]]], "page_692": [["block_0", ["This result is consistent with the provided value for K within nominal uncertainty, differing by just 1 in the\nleast significant digit\u2019s place.\n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["The equilibrium constant Kc for the reaction of nitrogen and hydrogen to produce ammonia at a certain\ntemperature is 6.00\n10. Calculate the equilibrium concentration of ammonia if the equilibrium\n"]], ["block_3", ["concentrations of nitrogen and hydrogen are 4.26 M and 2.09 M, respectively.\n"]], ["block_4", [" Answer: \n1.53 mol/L\n"]], ["block_5", [" Calculation of Equilibrium Concentrations from Initial Concentrations \n"]], ["block_6", ["Perhaps the most challenging type of equilibrium calculation can be one in which equilibrium concentrations\nare derived from initial concentrations and an equilibrium constant. For these calculations, a four-step\napproach is typically useful:\n"]], ["block_7", ["The last two example exercises of this chapter demonstrate the application of this strategy.\n"]], ["block_8", [" Calculation of Equilibrium Concentrations \n"]], ["block_9", ["Under certain conditions, the equilibrium constant Kc for the decomposition of PCl5(g) into PCl3(g) and Cl2(g) is\n0.0211. What are the equilibrium concentrations of PCl5, PCl3, and Cl2 in a mixture that initially contained only\nPCl5 at a concentration of 1.00 M?\n"]], ["block_10", [" Solution \n"]], ["block_11", ["Use the stepwise process described earlier.\n"]], ["block_12", ["1.\nIdentify the direction in which the reaction will proceed to reach equilibrium.\n"]], ["block_13", ["2.\nDevelop an ICE table.\n"]], ["block_14", ["3.\nCalculate the concentration changes and, subsequently, the equilibrium concentrations.\n"]], ["block_15", ["4.\nConfirm the calculated equilibrium concentrations.\n"]], ["block_16", ["Step 1.\nDetermine the direction the reaction proceeds.\n"]], ["block_17", ["Step 2.\nDevelop an ICE table.\n"]], ["block_18", ["Step 3.\nSolve for the change and the equilibrium concentrations.\n"]], ["block_19", ["The balanced equation for the decomposition of PCl5 is\n"]], ["block_20", ["Because only the reactant is present initially Qc = 0 and the reaction will proceed to the right.\n"]], ["block_21", [{"image_0": "692_0.png", "coords": [90, 581, 441, 676]}]], ["block_22", ["Substituting the equilibrium concentrations into the equilibrium constant equation gives\n"]], ["block_23", ["EXAMPLE 13.9\n"]], ["block_24", [" 13.4 \u2022 Equilibrium Calculations \n 679 \n"]]], "page_693": [["block_0", [" 680 \n 13 \u2022 Fundamental Equilibrium Concepts \n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["Acetic acid, CH3CO2H, reacts with ethanol, C2H5OH, to form water and ethyl acetate, CH3CO2C2H5.\n"]], ["block_3", [" Access for free at openstax.org \n"]], ["block_4", ["Step 4.\nConfirm the calculated equilibrium concentrations.\n"]], ["block_5", ["Appendix B shows an equation of the form ax+ bx + c = 0 can be rearranged to solve for x:\n"]], ["block_6", ["In this case, a = 1, b = 0.0211, and c = \u22120.0211. Substituting the appropriate values for a, b, and c yields:\n"]], ["block_7", ["The two roots of the quadratic are, therefore,\n"]], ["block_8", ["and\n"]], ["block_9", ["For this scenario, only the positive root is physically meaningful (concentrations are either zero or\npositive), and so x = 0.135 M.\n"]], ["block_10", ["The equilibrium concentrations are\n"]], ["block_11", ["Substitution into the expression for Kc (to check the calculation) gives\n"]], ["block_12", ["The equilibrium constant calculated from the equilibrium concentrations is equal to the value of Kc given\nin the problem (when rounded to the proper number of significant figures).\n"]]], "page_694": [["block_0", ["The equilibrium constant for this reaction with dioxane as a solvent is 4.0. What are the equilibrium\nconcentrations for a mixture that is initially 0.15 M in CH3CO2H, 0.15 M in C2H5OH, 0.40 M in CH3CO2C2H5,\nand 0.40 M in H2O?\n"]], ["block_1", [" Answer: \n[CH3CO2H] = 0.18 M, [C2H5OH] = 0.18 M, [CH3CO2C2H5] = 0.37 M, [H2O] = 0.37 M\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["A 1.00-L flask is filled with 1.00 mole of H2 and 2.00 moles of I2. The value of the equilibrium constant for the\nreaction of hydrogen and iodine reacting to form hydrogen iodide is 50.5 under the given conditions. What are\nthe equilibrium concentrations of H2, I2, and HI in moles/L?\n"]], ["block_4", [" Answer: \n[H2] = 0.06 M, [I2] = 1.06 M, [HI] = 1.88 M\n"]], ["block_5", [" Calculation of Equilibrium Concentrations Using an Algebra-Simplifying Assumption \n"]], ["block_6", ["What are the concentrations at equilibrium of a 0.15 M solution of HCN?\n"]], ["block_7", [" Solution \n"]], ["block_8", ["Using \u201cx\u201d to represent the concentration of each product at equilibrium gives this ICE table.\n"]], ["block_9", [{"image_0": "694_0.png", "coords": [72, 380, 423, 475]}]], ["block_10", ["Substitute the equilibrium concentration terms into the Kc expression\n"]], ["block_11", ["rearrange to the quadratic form and solve for x\n"]], ["block_12", ["Thus [H] = [CN] = x = 8.6\n10M and [HCN] = 0.15 \u2013 x = 0.15 M.\n"]], ["block_13", ["Note in this case that the change in concentration is significantly less than the initial concentration (a\nconsequence of the small K), and so the initial concentration experiences a negligible change:\n"]], ["block_14", ["This approximation allows for a more expedient mathematical approach to the calculation that avoids the need\nto solve for the roots of a quadratic equation:\n"]], ["block_15", ["EXAMPLE 13.10\n"]], ["block_16", [" 13.4 \u2022 Equilibrium Calculations \n 681 \n"]]], "page_695": [["block_0", [" 682 \n 13 \u2022 Fundamental Equilibrium Concepts \n"]], ["block_1", ["The value of x calculated is, indeed, much less than the initial concentration\n"]], ["block_2", ["and so the approximation was justified. If this simplified approach were to yield a value for x that did not\njustify the approximation, the calculation would need to be repeated without making the approximation.\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["What are the equilibrium concentrations in a 0.25 M NH3 solution?\n"]], ["block_5", [" Answer: \n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", ["[NH3] = 0.25 M\n"]]], "page_696": [["block_0", [" Key Terms \n"]], ["block_1", [" equilibrium \nstate of a reversible reaction in which\n"]], ["block_2", [" equilibrium constant (K) \nvalue of the reaction\n"]], ["block_3", [" heterogeneous equilibria \nequilibria in which\n"]], ["block_4", [" homogeneous equilibria \nequilibria in which all\n"]], ["block_5", [" law of mass action \nwhen a reversible reaction has\n"]], ["block_6", [" Key Equations \n"]], ["block_7", [" Summary \n"]], ["block_8", [" 13.1 Chemical Equilibria \n"]], ["block_9", ["A reversible reaction is at equilibrium when the\nforward and reverse processes occur at equal rates.\nChemical equilibria are dynamic processes\ncharacterized by constant amounts of reactant and\nproduct species.\n"]], ["block_10", [" 13.2 Equilibrium Constants \n"]], ["block_11", ["The composition of a reaction mixture may be\nrepresented by a mathematical function known as\nthe reaction quotient, Q. For a reaction at\nequilibrium, the composition is constant, and Q is\ncalled the equilibrium constant, K.\n"]], ["block_12", ["A homogeneous equilibrium is an equilibrium in\nwhich all components are in the same phase. A\nheterogeneous equilibrium is an equilibrium in\nwhich components are in two or more phases.\n"]], ["block_13", [" 13.3 Shifting Equilibria: Le Ch\u00e2telier\u2019s \n Principle \n"]], ["block_14", ["Systems at equilibrium can be disturbed by changes\n"]], ["block_15", ["P = MRT\n"]], ["block_16", ["Kc = Qc at equilibrium\n"]], ["block_17", ["Kp = Qp at equilibrium\n"]], ["block_18", ["KP = Kc (RT)\n"]], ["block_19", ["the forward and reverse processes occur at equal\nrates\n"]], ["block_20", ["quotient for a system at equilibrium; may be\nexpressed using concentrations (Kc) or partial\npressures (Kp)\n"]], ["block_21", ["reactants and products occupy two or more\ndifferent phases\n"]], ["block_22", ["reactants and products occupy the same phase\n"]], ["block_23", [" Le Ch\u00e2telier\u2019s principle \nan equilibrium subjected\n"]], ["block_24", [" reaction quotient (Q) \nmathematical function\n"]], ["block_25", [" reversible reaction \nchemical reaction that can\n"]], ["block_26", ["to temperature, concentration, and, in some cases,\nvolume and pressure. The system\u2019s response to\nthese disturbances is described by Le Ch\u00e2telier\u2019s\nprinciple: An equilibrium system subjected to a\ndisturbance will shift in a way that counters the\ndisturbance and re-establishes equilibrium. A\ncatalyst will increase the rate of both the forward\nand reverse reactions of a reversible process,\nincreasing the rate at which equilibrium is reached\nbut not altering the equilibrium mixture\u2019s\ncomposition (K does not change).\n"]], ["block_27", [" 13.4 Equilibrium Calculations \n"]], ["block_28", ["Calculating values for equilibrium constants and/or\nequilibrium concentrations is of practical benefit to\nmany applications. A mathematical strategy that\nuses initial concentrations, changes in\nconcentrations, and equilibrium concentrations\n(and goes by the acronym ICE) is useful for several\ntypes of equilibrium calculations.\n"]], ["block_29", ["attained equilibrium at a given temperature, the\nreaction quotient remains constant\n"]], ["block_30", ["to stress will shift in a way to counter the stress\nand re-establish equilibrium\n"]], ["block_31", ["describing the relative amounts of reactants and\nproducts in a reaction mixture; may be expressed\nin terms of concentrations (Qc) or pressures (Qp)\n"]], ["block_32", ["proceed in both the forward and reverse\ndirections under given conditions\n"]], ["block_33", [" 13 \u2022 Key Terms \n 683 \n"]]], "page_697": [["block_0", [" 684 \n 13 \u2022 Exercises \n"]], ["block_1", [" Exercises \n"]], ["block_2", [" 13.1 Chemical Equilibria \n"]], ["block_3", [" 13.2 Equilibrium Constants \n"]], ["block_4", [" 10 . Among the solubility rules previously discussed is the statement: Carbonates, phosphates, borates, and\n"]], ["block_5", [" 11 . Benzene is one of the compounds used as octane enhancers in unleaded gasoline. It is manufactured by\n"]], ["block_6", [" 12 . Show that the complete chemical equation, the total ionic equation, and the net ionic equation for the\n"]], ["block_7", [" 13 . For a titration to be effective, the reaction must be rapid and the yield of the reaction must essentially be\n"]], ["block_8", [" 14 . For a precipitation reaction to be useful in a gravimetric analysis, the product of the reaction must be\n"]], ["block_9", [" 15 . Write the mathematical expression for the reaction quotient, Qc, for each of the following reactions:\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [" 1 . What does it mean to describe a reaction as \u201creversible\u201d?\n 2 . When writing an equation, how is a reversible reaction distinguished from a nonreversible reaction?\n 3 . If a reaction is reversible, when can it be said to have reached equilibrium?\n 4 . Is a system at equilibrium if the rate constants of the forward and reverse reactions are equal?\n 5 . If the concentrations of products and reactants are equal, is the system at equilibrium?\n"]], ["block_12", [" 6 . Explain why there may be an infinite number of values for the reaction quotient of a reaction at a given\n"]], ["block_13", [" 7 . Explain why an equilibrium between Br2(l) and Br2(g) would not be established if the container were not a\n"]], ["block_14", [" 8 . If you observe the following reaction at equilibrium, is it possible to tell whether the reaction started with\n"]], ["block_15", [" 9 . Among the solubility rules previously discussed is the statement: All chlorides are soluble except Hg2Cl2,\n"]], ["block_16", ["temperature but there can be only one value for the equilibrium constant at that temperature.\n"]], ["block_17", ["closed vessel shown in Figure 13.4.\n"]], ["block_18", ["pure NO2 or with pure N2O4?\n"]], ["block_19", ["AgCl, PbCl2, and CuCl.\n(a) Write the expression for the equilibrium constant for the reaction represented by the equation\n"]], ["block_20", ["(b) Write the expression for the equilibrium constant for the reaction represented by the equation\n"]], ["block_21", ["arsenates\u2014except those of the ammonium ion and the alkali metals\u2014are insoluble.\n(a) Write the expression for the equilibrium constant for the reaction represented by the equation\n"]], ["block_22", ["(b) Write the expression for the equilibrium constant for the reaction represented by the equation\n"]], ["block_23", ["the catalytic conversion of acetylene to benzene:\nWhich value of Kc would make\n"]], ["block_24", ["this reaction most useful commercially? Kc \u2248 0.01, Kc \u2248 1, or Kc \u2248 10. Explain your answer.\n"]], ["block_25", ["reaction represented by the equation\ngive the same expression for the\n"]], ["block_26", ["reaction quotient. KI3 is composed of the ions Kand\n"]], ["block_27", ["100%. Is Kc > 1, < 1, or \u2248 1 for a titration reaction?\n"]], ["block_28", ["insoluble. Is Kc > 1, < 1, or \u2248 1 for a useful precipitation reaction?\n"]], ["block_29", ["(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n(g)\n(h)\n"]], ["block_30", ["Is Kc > 1, < 1, or \u2248 1? Explain your answer.\n"]], ["block_31", ["Is Kc > 1, < 1, or \u2248 1? Explain your answer.\n"]], ["block_32", ["Is Kc > 1, < 1, or \u2248 1? Explain your answer.\n"]], ["block_33", ["Is Kc > 1, < 1, or \u2248 1? Explain your answer.\n"]]], "page_698": [["block_0", [" 16 . Write the mathematical expression for the reaction quotient, Qc, for each of the following reactions:\n"]], ["block_1", [" 17 . The initial concentrations or pressures of reactants and products are given for each of the following\n"]], ["block_2", [" 18 . The initial concentrations or pressures of reactants and products are given for each of the following\n"]], ["block_3", [" 19 . The following reaction has KP = 4.50\n10at 720 K.\n"]], ["block_4", [" 20 . Determine if the following system is at equilibrium. If not, in which direction will the system need to shift\n"]], ["block_5", [" 21 . Which of the systems described in Exercise 13.15 are homogeneous equilibria? Which are heterogeneous\n"]], ["block_6", [" 22 . Which of the systems described in Exercise 13.16 are homogeneous equilibria? Which are heterogeneous\n"]], ["block_7", [" 23 . For which of the reactions in Exercise 13.15 does Kc (calculated using concentrations) equal KP (calculated\n"]], ["block_8", [" 24 . For which of the reactions in Exercise 13.16 does Kc (calculated using concentrations) equal KP (calculated\n"]], ["block_9", [" 25 . Convert the values of Kc to values of KP or the values of KP to values of Kc.\n"]], ["block_10", ["(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n(g)\n(h)\n"]], ["block_11", ["systems. Calculate the reaction quotient and determine the direction in which each system will proceed to\nreach equilibrium.\n(a)\n[NH3] = 0.20 M, [N2] = 1.00 M, [H2] = 1.00 M\n"]], ["block_12", ["(b)\nNH3 = 3.0 atm, N2 = 2.0 atm, H2 = 1.0 atm\n"]], ["block_13", ["(c)\n[SO3] = 0.00 M, [SO2] = 1.00 M, [O2] = 1.00 M\n"]], ["block_14", ["(d)\nSO3 = 1.00 atm, SO2 = 1.00 atm, O2 = 1.00 atm\n"]], ["block_15", ["(e)\n[NO] = 1.00 M, [Cl2] = 1.00 M, [NOCl] = 0 M\n"]], ["block_16", ["(f)\nNO = 10.0 atm, N2 = O2 = 5 atm\n"]], ["block_17", ["systems. Calculate the reaction quotient and determine the direction in which each system will proceed to\nreach equilibrium.\n(a)\n[NH3] = 0.50 M, [N2] = 0.15 M, [H2] = 0.12 M\n"]], ["block_18", ["(b)\nNH3 = 2.00 atm, N2 = 10.00 atm, H2 = 10.00\n"]], ["block_19", ["atm\n(c)\n[SO3] = 2.00 M, [SO2] = 2.00 M, [O2] = 2.00 M\n"]], ["block_20", ["(d)\nSO2 = 1.00 atm, O2 = 1.130 atm, SO3 = 0 atm\n"]], ["block_21", ["(e)\nNO = 1.00 atm, Cl2 = 1.00 atm, NOCl = 0\n"]], ["block_22", ["atm\n(f)\n[N2] = 0.100 M, [O2] = 0.200 M, [NO] = 1.00 M\n"]], ["block_23", ["If a reaction vessel is filled with each gas to the partial pressures listed, in which direction will it shift to\nreach equilibrium? P(NH3) = 93 atm, P(N2) = 48 atm, and P(H2) = 52 atm\n"]], ["block_24", ["to reach equilibrium?\n"]], ["block_25", ["[SO2Cl2] = 0.12 M, [Cl2] = 0.16 M and [SO2] = 0.050 M. Kc for the reaction is 0.078.\n"]], ["block_26", ["equilibria?\n"]], ["block_27", ["equilibria?\n"]], ["block_28", ["using pressures)?\n"]], ["block_29", ["using pressures)?\n"]], ["block_30", ["(a)\n(b)\n(c)\n(d)\n"]], ["block_31", [" 13 \u2022 Exercises \n 685 \n"]]], "page_699": [["block_0", [" 686 \n 13 \u2022 Exercises \n"]], ["block_1", [" 26 . Convert the values of Kc to values of KP or the values of KP to values of Kc.\n"]], ["block_2", [" 27 . What is the value of the equilibrium constant expression for the change\nat 30 \u00b0C? (See\n"]], ["block_3", [" 28 . Write the expression of the reaction quotient for the ionization of HOCN in water.\n 29 . Write the reaction quotient expression for the ionization of NH3 in water.\n 30 . What is the approximate value of the equilibrium constant KP for the change\n"]], ["block_4", [" 13.3 Shifting Equilibria: Le Ch\u00e2telier\u2019s Principle \n"]], ["block_5", [" 31 . The following equation represents a reversible decomposition:\n"]], ["block_6", [" 32 . Explain how to recognize the conditions under which changes in volume will affect gas-phase systems at\n"]], ["block_7", [" 33 . What property of a reaction can we use to predict the effect of a change in temperature on the value of an\n"]], ["block_8", [" 34 . The following reaction occurs when a burner on a gas stove is lit:\n"]], ["block_9", [" 35 . A necessary step in the manufacture of sulfuric acid is the formation of sulfur trioxide, SO3, from sulfur\n"]], ["block_10", [" 36 . Suggest four ways in which the concentration of hydrazine, N2H4, could be increased in an equilibrium\n"]], ["block_11", [" 37 . Suggest four ways in which the concentration of PH3 could be increased in an equilibrium described by\n"]], ["block_12", [" 38 . How will an increase in temperature affect each of the following equilibria? How will a decrease in the\n"]], ["block_13", [" 39 . How will an increase in temperature affect each of the following equilibria? How will a decrease in the\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["(a)\n(b)\n(c)\n(d)\n"]], ["block_16", ["Appendix E.)\n"]], ["block_17", ["torr at 25 \u00b0C.)\n"]], ["block_18", ["Under what conditions will decomposition in a closed container proceed to completion so that no CaCO3\nremains?\n"]], ["block_19", ["equilibrium.\n"]], ["block_20", ["equilibrium constant?\n"]], ["block_21", ["Is an equilibrium among CH4, O2, CO2, and H2O established under these conditions? Explain your answer.\n"]], ["block_22", ["dioxide, SO2, and oxygen, O2, shown here. At high temperatures, the rate of formation of SO3 is higher, but\nthe equilibrium amount (concentration or partial pressure) of SO3 is lower than it would be at lower\ntemperatures.\n"]], ["block_23", ["(a) Does the equilibrium constant for the reaction increase, decrease, or remain about the same as the\ntemperature increases?\n(b) Is the reaction endothermic or exothermic?\n"]], ["block_24", ["described by the following equation:\n"]], ["block_25", ["the following equation:\n"]], ["block_26", ["volume of the reaction vessel affect each?\n(a)\n(b)\n(c)\n(d)\n"]], ["block_27", ["volume of the reaction vessel affect each?\n(a)\n(b)\n(c)\n(d)\n"]], ["block_28", ["at 25 \u00b0C. (The equilibrium vapor pressure for this substance is 570\n"]]], "page_700": [["block_0", [" 40 . Methanol can be prepared from carbon monoxide and hydrogen at high temperature and pressure in the\n"]], ["block_1", [" 41 . Nitrogen and oxygen react at high temperatures.\n"]], ["block_2", [" 42 . Water gas, a mixture of H2 and CO, is an important industrial fuel produced by the reaction of steam with\n"]], ["block_3", [" 43 . Pure iron metal can be produced by the reduction of iron(III) oxide with hydrogen gas.\n"]], ["block_4", [" 44 . Ammonia is a weak base that reacts with water according to this equation:\n"]], ["block_5", [" 45 . Acetic acid is a weak acid that reacts with water according to this equation:\n"]], ["block_6", ["presence of a suitable catalyst.\n(a) Write the expression for the equilibrium constant (Kc) for the reversible reaction\n"]], ["block_7", ["(b) What will happen to the concentrations of H2, CO, and CH3OH at equilibrium if more H2 is added?\n(c) What will happen to the concentrations of H2, CO, and CH3OH at equilibrium if CO is removed?\n(d) What will happen to the concentrations of H2, CO, and CH3OH at equilibrium if CH3OH is added?\n(e) What will happen to the concentrations of H2, CO, and CH3OH at equilibrium if the temperature of the\nsystem is increased?\n(f) What will happen to the concentrations of H2, CO, and CH3OH at equilibrium if more catalyst is added?\n"]], ["block_8", ["(a) Write the expression for the equilibrium constant (Kc) for the reversible reaction\n"]], ["block_9", ["(b) What will happen to the concentrations of N2, O2, and NO at equilibrium if more O2 is added?\n(c) What will happen to the concentrations of N2, O2, and NO at equilibrium if N2 is removed?\n(d) What will happen to the concentrations of N2, O2, and NO at equilibrium if NO is added?\n(e) What will happen to the concentrations of N2, O2, and NO at equilibrium if the volume of the reaction\nvessel is decreased?\n(f) What will happen to the concentrations of N2, O2, and NO at equilibrium if the temperature of the\nsystem is increased?\n(g) What will happen to the concentrations of N2, O2, and NO at equilibrium if a catalyst is added?\n"]], ["block_10", ["red hot coke, essentially pure carbon.\n(a) Write the expression for the equilibrium constant for the reversible reaction\n"]], ["block_11", ["(b) What will happen to the concentration of each reactant and product at equilibrium if more C is added?\n(c) What will happen to the concentration of each reactant and product at equilibrium if H2O is removed?\n(d) What will happen to the concentration of each reactant and product at equilibrium if CO is added?\n(e) What will happen to the concentration of each reactant and product at equilibrium if the temperature\nof the system is increased?\n"]], ["block_12", ["(a) Write the expression for the equilibrium constant (Kc) for the reversible reaction\n"]], ["block_13", ["(b) What will happen to the concentration of each reactant and product at equilibrium if more Fe is added?\n(c) What will happen to the concentration of each reactant and product at equilibrium if H2O is removed?\n(d) What will happen to the concentration of each reactant and product at equilibrium if H2 is added?\n(e) What will happen to the concentration of each reactant and product at equilibrium if the volume of the\nreaction vessel is decreased?\n(f) What will happen to the concentration of each reactant and product at equilibrium if the temperature\nof the system is increased?\n"]], ["block_14", ["Will any of the following increase the percent of ammonia that is converted to the ammonium ion in\nwater?\n(a) Addition of NaOH\n(b) Addition of HCl\n(c) Addition of NH4Cl\n"]], ["block_15", ["Will any of the following increase the percent of acetic acid that reacts and produces\nion?\n"]], ["block_16", ["(a) Addition of HCl\n(b) Addition of NaOH\n(c) Addition of NaCH3CO2\n"]], ["block_17", [" 13 \u2022 Exercises \n 687 \n"]]], "page_701": [["block_0", [" 688 \n 13 \u2022 Exercises \n"]], ["block_1", [" 46 . Suggest two ways in which the equilibrium concentration of Agcan be reduced in a solution of Na, Cl,\n"]], ["block_2", [" 47 . How can the pressure of water vapor be increased in the following equilibrium?\n"]], ["block_3", [" 48 . A solution is saturated with silver sulfate and contains excess solid silver sulfate:\n"]], ["block_4", [" 49 . When equal molar amounts of HCl and HOCl are dissolved separately in equal amounts of water, the\n"]], ["block_5", [" 13.4 Equilibrium Calculations \n"]], ["block_6", [" 50 . A reaction is represented by this equation:\n"]], ["block_7", [" 51 . A reaction is represented by this equation:\n"]], ["block_8", [" 52 . What is the value of the equilibrium constant at 500 \u00b0C for the formation of NH3 according to the following\n"]], ["block_9", [" 53 . Hydrogen is prepared commercially by the reaction of methane and water vapor at elevated temperatures.\n"]], ["block_10", [" 54 . A 0.72-mol sample of PCl5 is put into a 1.00-L vessel and heated. At equilibrium, the vessel contains 0.40\n"]], ["block_11", [" 55 . At 1 atm and 25 \u00b0C, NO2 with an initial concentration of 1.00 M is 0.0033% decomposed into NO and O2.\n"]], ["block_12", [" 56 . Calculate the value of the equilibrium constant KP for the reaction\nfrom\n"]], ["block_13", [" 57 . When heated, iodine vapor dissociates according to this equation:\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["Ag, and\nin contact with solid AgCl.\n"]], ["block_16", ["A small amount of solid silver sulfate containing a radioactive isotope of silver is added to this solution.\nWithin a few minutes, a portion of the solution phase is sampled and tests positive for radioactive Ag\n"]], ["block_17", ["ions. Explain this observation.\n"]], ["block_18", ["solution of HCl freezes at a lower temperature. Which compound has the larger equilibrium constant for\nacid ionization?\n(a) HCl\n(b) H+ Cl\n"]], ["block_19", ["(c) HOCl\n(d) H+ OCl\n"]], ["block_20", ["(a) Write the mathematical expression for the equilibrium constant.\n(b) Using concentrations \u22641 M, identify two sets of concentrations that describe a mixture of A, B, and C at\nequilibrium.\n"]], ["block_21", ["(a) Write the mathematical expression for the equilibrium constant.\n(b) Using concentrations of \u22641 M, identify two sets of concentrations that describe a mixture of W, X, and Y\nat equilibrium.\n"]], ["block_22", ["equation?\n"]], ["block_23", ["An equilibrium mixture of NH3(g), H2(g), and N2(g) at 500 \u00b0C was found to contain 1.35 M H2, 1.15 M N2,\nand 4.12\n10M NH3.\n"]], ["block_24", ["What is the equilibrium constant for the reaction if a mixture at equilibrium contains gases with the\nfollowing concentrations: CH4, 0.126 M; H2O, 0.242 M; CO, 0.126 M; H2 1.15 M, at a temperature of 760 \u00b0C?\n"]], ["block_25", ["mol of PCl3(g) and 0.40 mol of Cl2(g). Calculate the value of the equilibrium constant for the decomposition\nof PCl5 to PCl3 and Cl2 at this temperature.\n"]], ["block_26", ["Calculate the value of the equilibrium constant for the reaction.\n"]], ["block_27", ["these equilibrium pressures: NO, 0.050 atm; Cl2, 0.30 atm; NOCl, 1.2 atm.\n"]], ["block_28", ["At 1274 K, a sample exhibits a partial pressure of I2 of 0.1122 atm and a partial pressure due to I atoms of\n0.1378 atm. Determine the value of the equilibrium constant, KP, for the decomposition at 1274 K.\n"]]], "page_702": [["block_0", [" 58 . A sample of ammonium chloride was heated in a closed container.\n"]], ["block_1", [" 59 . At a temperature of 60 \u00b0C, the vapor pressure of water is 0.196 atm. What is the value of the equilibrium\n"]], ["block_2", [" 60 . Complete the following partial ICE tables.\n"]], ["block_3", [" 61 . Complete the following partial ICE tables.\n"]], ["block_4", [" 62 . Why are there no changes specified for Ni in Exercise 13.60, part (f)? What property of Ni does change?\n 63 . Why are there no changes specified for NH4HS in Exercise 13.61, part (e)? What property of NH4HS does\n"]], ["block_5", ["At equilibrium, the pressure of NH3(g) was found to be 1.75 atm. What is the value of the equilibrium\nconstant KP for the decomposition at this temperature?\n"]], ["block_6", ["constant KP for the vaporization equilibrium at 60 \u00b0C?\n"]], ["block_7", ["(a)\n"]], ["block_8", ["(b)\n"]], ["block_9", ["(c)\n"]], ["block_10", ["(d)\n"]], ["block_11", ["(e)\n"]], ["block_12", ["(f)\n"]], ["block_13", ["(a)\n"]], ["block_14", ["(b)\n"]], ["block_15", ["(c)\n"]], ["block_16", ["(d)\n"]], ["block_17", ["(e)\n"]], ["block_18", ["(f)\n"]], ["block_19", ["change?\n"]], ["block_20", [" 13 \u2022 Exercises \n 689 \n"]]], "page_703": [["block_0", [" 690 \n 13 \u2022 Exercises \n"]], ["block_1", [" 64 . Analysis of the gases in a sealed reaction vessel containing NH3, N2, and H2 at equilibrium at 400 \u00b0C\n"]], ["block_2", [" 65 . Calculate the number of moles of HI that are at equilibrium with 1.25 mol of H2 and 1.25 mol of I2 in a\n"]], ["block_3", [" 66 . What is the pressure of BrCl in an equilibrium mixture of Cl2, Br2, and BrCl if the pressure of Cl2 in the\n"]], ["block_4", [" 67 . What is the pressure of CO2 in a mixture at equilibrium that contains 0.50 atm H2, 2.0 atm of H2O, and 1.0\n"]], ["block_5", [" 68 . Cobalt metal can be prepared by reducing cobalt(II) oxide with carbon monoxide.\n"]], ["block_6", [" 69 . Carbon reacts with water vapor at elevated temperatures.\n"]], ["block_7", [" 70 . Sodium sulfate 10\u2212hydrate, Na2SO4\u00b710H2O, dehydrates according to the equation\n"]], ["block_8", [" 71 . Calcium chloride 6\u2212hydrate, CaCl2\u00b76H2O, dehydrates according to the equation\n"]], ["block_9", [" 72 . A student solved the following problem and found the equilibrium concentrations to be [SO2] = 0.590 M,\n"]], ["block_10", [" 73 . A student solved the following problem and found [N2O4] = 0.16 M at equilibrium. How could this student\n"]], ["block_11", [" 74 . Assume that the change in concentration of N2O4 is small enough to be neglected in the following\n"]], ["block_12", [" 75 . Assume that the change in concentration of COCl2 is small enough to be neglected in the following\n"]], ["block_13", [" 76 . Assume that the change in pressure of H2S is small enough to be neglected in the following problem.\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["recognize that the answer was wrong without reworking the problem? The problem was: What is the\nequilibrium concentration of N2O4 in a mixture formed from a sample of NO2 with a concentration of 0.10\nM?\n"]], ["block_16", ["established the concentration of N2 to be 1.2 M and the concentration of H2 to be 0.24 M.\n"]], ["block_17", ["Calculate the equilibrium molar concentration of NH3.\n"]], ["block_18", ["5.00\u2212L flask at 448 \u00b0C.\n"]], ["block_19", ["mixture is 0.115 atm and the pressure of Br2 in the mixture is 0.450 atm?\n"]], ["block_20", ["atm of CO at 990 \u00b0C?\n"]], ["block_21", ["What concentration of CO remains in an equilibrium mixture with [CO2] = 0.100 M?\n"]], ["block_22", ["Assuming a reaction mixture initially contains only reactants, what is the concentration of CO in an\nequilibrium mixture with [H2O] = 0.500 M at 1000 \u00b0C?\n"]], ["block_23", ["What is the pressure of water vapor at equilibrium with a mixture of Na2SO4\u00b710H2O and NaSO4?\n"]], ["block_24", ["What is the pressure of water vapor at equilibrium with a mixture of CaCl2\u00b76H2O and CaCl2 at 25 \u00b0C?\n"]], ["block_25", ["[O2] = 0.0450 M, and [SO3] = 0.260 M. How could this student check the work without reworking the\nproblem? The problem was: For the following reaction at 600 \u00b0C:\n"]], ["block_26", ["problem.\n(a) Calculate the equilibrium concentration of both species in 1.00 L of a solution prepared from 0.129 mol\nof N2O4 with chloroform as the solvent.\n"]], ["block_27", ["(b) Confirm that the change is small enough to be neglected.\n"]], ["block_28", ["problem.\n(a) Calculate the equilibrium concentration of all species in an equilibrium mixture that results from the\ndecomposition of COCl2 with an initial concentration of 0.3166 M.\n"]], ["block_29", ["(b) Confirm that the change is small enough to be neglected.\n"]], ["block_30", ["(a) Calculate the equilibrium pressures of all species in an equilibrium mixture that results from the\ndecomposition of H2S with an initial pressure of 0.824 atm.\n"]], ["block_31", ["(b) Confirm that the change is small enough to be neglected.\n"]], ["block_32", ["in chloroform\n"]]], "page_704": [["block_0", [" 77 . What are all concentrations after a mixture that contains [H2O] = 1.00 M and [Cl2O] = 1.00 M comes to\n"]], ["block_1", [" 78 . What are the concentrations of PCl5, PCl3, and Cl2 in an equilibrium mixture produced by the\n"]], ["block_2", [" 79 . Calculate the number of grams of HI that are at equilibrium with 1.25 mol of H2 and 63.5 g of iodine at 448\n"]], ["block_3", [" 80 . Butane exists as two isomers, n\u2212butane and isobutane.\n"]], ["block_4", [" 81 . What is the minimum mass of CaCO3 required to establish equilibrium at a certain temperature in a\n"]], ["block_5", [" 82 . The equilibrium constant (Kc) for this reaction is 1.60 at 990 \u00b0C:\n"]], ["block_6", [" 83 . In a 3.0-L vessel, the following equilibrium partial pressures are measured: N2, 190 torr; H2, 317 torr;\n"]], ["block_7", [" 84 . The equilibrium constant (Kc) for this reaction is 5.0 at a given temperature.\n"]], ["block_8", [" 85 . Antimony pentachloride decomposes according to this equation:\n"]], ["block_9", ["KP = 2.5 at 25 \u00b0C\nWhat is the pressure of isobutane in a container of the two isomers at equilibrium with a total pressure of\n1.22 atm?\n"]], ["block_10", ["equilibrium at 25 \u00b0C?\n"]], ["block_11", ["decomposition of a sample of pure PCl5 with [PCl5] = 2.00 M?\n"]], ["block_12", ["\u00b0C.\n"]], ["block_13", [{"image_0": "704_0.png", "coords": [91, 183, 325, 244]}]], ["block_14", ["6.50-L container if the equilibrium constant (Kc) is 0.50 for the decomposition reaction of CaCO3 at that\ntemperature?\n"]], ["block_15", ["Calculate the number of moles of each component in the final equilibrium mixture obtained from adding\n1.00 mol of H2, 2.00 mol of CO2, 0.750 mol of H2O, and 1.00 mol of CO to a 5.00-L container at 990 \u00b0C.\n"]], ["block_16", ["NH3, 1.00\n10torr.\n"]], ["block_17", ["(a) How will the partial pressures of H2, N2, and NH3 change if H2 is removed from the system? Will they\nincrease, decrease, or remain the same?\n(b) Hydrogen is removed from the vessel until the partial pressure of nitrogen, at equilibrium, is 250 torr.\nCalculate the partial pressures of the other substances under the new conditions.\n"]], ["block_18", ["(a) On analysis, an equilibrium mixture of the substances present at the given temperature was found to\ncontain 0.20 mol of CO, 0.30 mol of water vapor, and 0.90 mol of H2 in a liter. How many moles of CO2 were\nthere in the equilibrium mixture?\n(b) Maintaining the same temperature, additional H2 was added to the system, and some water vapor was\nremoved by drying. A new equilibrium mixture was thereby established containing 0.40 mol of CO, 0.30\nmol of water vapor, and 1.2 mol of H2 in a liter. How many moles of CO2 were in the new equilibrium\nmixture? Compare this with the quantity in part (a), and discuss whether the second value is reasonable.\nExplain how it is possible for the water vapor concentration to be the same in the two equilibrium\nsolutions even though some vapor was removed before the second equilibrium was established.\n"]], ["block_19", ["An equilibrium mixture in a 5.00-L flask at 448 \u00b0C contains 3.85 g of SbCl5, 9.14 g of SbCl3, and 2.84 g of\nCl2. How many grams of each will be found if the mixture is transferred into a 2.00-L flask at the same\ntemperature?\n"]], ["block_20", [" 13 \u2022 Exercises \n 691 \n"]]], "page_705": [["block_0", [" 692 \n 13 \u2022 Exercises \n"]], ["block_1", [" 86 . Consider the equilibrium\n"]], ["block_2", [" 87 . The binding of oxygen by hemoglobin (Hb), giving oxyhemoglobin (HbO2), is partially regulated by the\n"]], ["block_3", [" 88 . Liquid N2O3 is dark blue at low temperatures, but the color fades and becomes greenish at higher\n"]], ["block_4", [" 89 . A 1.00-L vessel at 400 \u00b0C contains the following equilibrium concentrations: N2, 1.00 M; H2, 0.50 M; and\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", ["(a) What is the expression for the equilibrium constant (Kc) of the reaction?\n(b) How must the concentration of NH3 change to reach equilibrium if the reaction quotient is less than\nthe equilibrium constant?\n(c) If the reaction were at equilibrium, how would an increase in the volume of the reaction vessel affect\nthe pressure of NO2?\n(d) If the change in the pressure of NO2 is 28 torr as a mixture of the four gases reaches equilibrium, how\nmuch will the pressure of O2 change?\n"]], ["block_7", ["concentration of H3Oand dissolved CO2 in the blood. Although the equilibrium is complicated, it can be\nsummarized as\n"]], ["block_8", ["(a) Write the equilibrium constant expression for this reaction.\n(b) Explain why the production of lactic acid and CO2 in a muscle during exertion stimulates release of O2\nfrom the oxyhemoglobin in the blood passing through the muscle.\n"]], ["block_9", ["temperatures as the compound decomposes to NO and NO2. At 25 \u00b0C, a value of KP = 1.91 has been\nestablished for this decomposition. If 0.236 moles of N2O3 are placed in a 1.52-L vessel at 25 \u00b0C, calculate\nthe equilibrium partial pressures of N2O3(g), NO2(g), and NO(g).\n"]], ["block_10", ["NH3, 0.25 M. How many moles of hydrogen must be removed from the vessel to increase the\nconcentration of nitrogen to 1.1 M? The equilibrium reaction is\n"]]], "page_706": [["block_0", ["CHAPTER 14\nAcid-Base Equilibria\n"]], ["block_1", [{"image_0": "706_0.png", "coords": [72, 104, 622, 332]}]], ["block_2", [" Figure 14.1 \nSinkholes such as this are the result of reactions between acidic groundwaters and basic rock\n"]], ["block_3", ["formations, like limestone. (credit: modification of work by Emil Kehnel)\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 14.1 Br\u00f8nsted-Lowry Acids and Bases \n 14.2 pH and pOH \n 14.3 Relative Strengths of Acids and Bases \n 14.4 Hydrolysis of Salts \n 14.5 Polyprotic Acids \n 14.6 Buffers \n 14.7 Acid-Base Titrations \n"]], ["block_6", [" INTRODUCTION \n"]], ["block_7", ["ions of water, Hand OH, is widely encountered in nature and society. As introduced in another chapter of this\ntext, acid-base chemistry involves the transfer of hydrogen ions from donors (acids) to acceptors (bases).\nThese H+ transfer reactions are reversible, and the equilibria established by acid-base systems are essential\naspects of phenomena ranging from sinkhole formation (Figure 14.1) to oxygen transport in the human body.\nThis chapter will further explore acid-base chemistry with an emphasis on the equilibrium aspects of this\nimportant reaction class.\n"]], ["block_8", [" 14.1 Br\u00f8nsted-Lowry Acids and Bases \n"]], ["block_9", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_10", ["\u2022\nIdentify acids, bases, and conjugate acid-base pairs according to the Br\u00f8nsted-Lowry definition\n"]], ["block_11", ["\u2022\nWrite equations for acid and base ionization reactions\n"]], ["block_12", ["\u2022\nUse the ion-product constant for water to calculate hydronium and hydroxide ion concentrations\n"]], ["block_13", ["\u2022\nDescribe the acid-base behavior of amphiprotic substances\n"]], ["block_14", ["Liquid water is essential to life on our planet, and chemistry involving the characteristic\n"]]], "page_707": [["block_0", [" 694 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", ["The acid-base reaction class has been studied for quite some time. In 1680, Robert Boyle reported traits of acid\nsolutions that included their ability to dissolve many substances, to change the colors of certain natural dyes,\nand to lose these traits after coming in contact with alkali (base) solutions. In the eighteenth century, it was\nrecognized that acids have a sour taste, react with limestone to liberate a gaseous substance (now known to be\nCO2), and interact with alkalis to form neutral substances. In 1815, Humphry Davy contributed greatly to the\ndevelopment of the modern acid-base concept by demonstrating that hydrogen is the essential constituent of\nacids. Around that same time, Joseph Louis Gay-Lussac concluded that acids are substances that can\nneutralize bases and that these two classes of substances can be defined only in terms of each other. The\nsignificance of hydrogen was reemphasized in 1884 when Svante Arrhenius defined an acid as a compound\nthat dissolves in water to yield hydrogen cations (now recognized to be hydronium ions) and a base as a\ncompound that dissolves in water to yield hydroxide anions.\n"]], ["block_2", ["Johannes Br\u00f8nsted and Thomas Lowry proposed a more general description in 1923 in which acids and bases\nwere defined in terms of the transfer of hydrogen ions, H. (Note that these hydrogen ions are often referred to\nsimply as protons, since that subatomic particle is the only component of cations derived from the most\nabundant hydrogen isotope, H.) A compound that donates a proton to another compound is called a\n Br\u00f8nsted-Lowry acid , and a compound that accepts a proton is called a Br\u00f8nsted-Lowry base . An acid-base\nreaction is, thus, the transfer of a proton from a donor (acid) to an acceptor (base).\n"]], ["block_3", ["The concept of conjugate pairs is useful in describing Br\u00f8nsted-Lowry acid-base reactions (and other\nreversible reactions, as well). When an acid donates H, the species that remains is called the conjugate base \nof the acid because it reacts as a proton acceptor in the reverse reaction. Likewise, when a base accepts H, it is\nconverted to its conjugate acid . The reaction between water and ammonia illustrates this idea. In the forward\ndirection, water acts as an acid by donating a proton to ammonia and subsequently becoming a hydroxide ion,\nOH, the conjugate base of water. The ammonia acts as a base in accepting this proton, becoming an\nammonium ion,\nthe conjugate acid of ammonia. In the reverse direction, a hydroxide ion acts as a base\n"]], ["block_4", ["in accepting a proton from ammonium ion, which acts as an acid.\n"]], ["block_5", [{"image_0": "707_0.png", "coords": [72, 391, 423, 542]}]], ["block_6", ["The reaction between a Br\u00f8nsted-Lowry acid and water is called acid ionization . For example, when hydrogen\nfluoride dissolves in water and ionizes, protons are transferred from hydrogen fluoride molecules to water\nmolecules, yielding hydronium ions and fluoride ions:\n"]], ["block_7", [{"image_1": "707_1.png", "coords": [72, 589, 353, 679]}]], ["block_8", [" Base ionization of a species occurs when it accepts protons from water molecules. In the example below,\npyridine molecules, C5NH5, undergo base ionization when dissolved in water, yielding hydroxide and\npyridinium ions:\n"]], ["block_9", [" Access for free at openstax.org \n"]]], "page_708": [["block_0", [{"image_0": "708_0.png", "coords": [72, 57, 442, 185]}]], ["block_1", ["The preceding ionization reactions suggest that water may function as both a base (as in its reaction with\nhydrogen fluoride) and an acid (as in its reaction with ammonia). Species capable of either donating or\naccepting protons are called amphiprotic , or more generally, amphoteric , a term that may be used for acids\nand bases per definitions other than the Br\u00f8nsted-Lowry one. The equations below show the two possible acid-\nbase reactions for two amphiprotic species, bicarbonate ion and water:\n"]], ["block_2", ["The first equation represents the reaction of bicarbonate as an acid with water as a base, whereas the second\nrepresents reaction of bicarbonate as a base with water as an acid. When bicarbonate is added to water, both\nthese equilibria are established simultaneously and the composition of the resulting solution may be\ndetermined through appropriate equilibrium calculations, as described later in this chapter.\n"]], ["block_3", ["In the liquid state, molecules of an amphiprotic substance can react with one another as illustrated for water in\nthe equations below:\n"]], ["block_4", [{"image_1": "708_1.png", "coords": [72, 383, 423, 474]}]], ["block_5", ["The process in which like molecules react to yield ions is called autoionization . Liquid water undergoes\nautoionization to a very slight extent; at 25 \u00b0C, approximately two out of every billion water molecules are\nionized. The extent of the water autoionization process is reflected in the value of its equilibrium constant, the\n ion-product constant for water, K w :\n"]], ["block_6", ["The slight ionization of pure water is reflected in the small value of the equilibrium constant; at 25 \u00b0C, Kw has a\nvalue of 1.0\n10. The process is endothermic, and so the extent of ionization and the resulting\n"]], ["block_7", ["concentrations of hydronium ion and hydroxide ion increase with temperature. For example, at 100 \u00b0C, the\nvalue for Kw is about 5.6\n10, roughly 50 times larger than the value at 25 \u00b0C.\n"]], ["block_8", [" Ion Concentrations in Pure Water \n"]], ["block_9", ["What are the hydronium ion concentration and the hydroxide ion concentration in pure water at 25 \u00b0C?\n"]], ["block_10", [" Solution \n"]], ["block_11", ["The autoionization of water yields the same number of hydronium and hydroxide ions. Therefore, in pure\nwater, [H3O] = [OH] = x. At 25 \u00b0C:\n"]], ["block_12", ["EXAMPLE 14.1\n"]], ["block_13", [" 14.1 \u2022 Br\u00f8nsted-Lowry Acids and Bases \n 695 \n"]]], "page_709": [["block_0", [" 696 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", ["What is the hydronium ion concentration in an aqueous solution with a hydroxide ion concentration of 0.001\nM at 25 \u00b0C?\n"]], ["block_2", ["So:\n"]], ["block_3", ["The hydronium ion concentration and the hydroxide ion concentration are the same, 1.0\n10M.\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["The ion product of water at 80 \u00b0C is 2.4\n10. What are the concentrations of hydronium and hydroxide ions\n"]], ["block_6", ["in pure water at 80 \u00b0C?\n"]], ["block_7", [" Answer: \n[H3O] = [OH] = 4.9\n10M\n"]], ["block_8", [" The Inverse Relation between [H 3 O + ] and [OH \u2212 ] \n"]], ["block_9", ["A solution of an acid in water has a hydronium ion concentration of 2.0\n10M. What is the concentration of\n"]], ["block_10", ["hydroxide ion at 25 \u00b0C?\n"]], ["block_11", [" Solution \n"]], ["block_12", ["Use the value of the ion-product constant for water at 25 \u00b0C\n"]], ["block_13", ["to calculate the missing equilibrium concentration.\n"]], ["block_14", ["Rearrangement of the Kw expression shows that [OH] is inversely proportional to [H3O]:\n"]], ["block_15", ["Compared with pure water, a solution of acid exhibits a higher concentration of hydronium ions (due to\nionization of the acid) and a proportionally lower concentration of hydroxide ions. This may be explained via\nLe Ch\u00e2telier\u2019s principle as a left shift in the water autoionization equilibrium resulting from the stress of\nincreased hydronium ion concentration.\n"]], ["block_16", ["Substituting the ion concentrations into the Kw expression confirms this calculation, resulting in the expected\nvalue:\n"]], ["block_17", [" Check Your Learning \n"]], ["block_18", [" Answer: \n[H3O] = 1\n10M\n"]], ["block_19", [" Representing the Acid-Base Behavior of an Amphoteric Substance \n"]], ["block_20", ["Write separate equations representing the reaction of\n"]], ["block_21", ["(a) as an acid with OH\n"]], ["block_22", [" Access for free at openstax.org \n"]], ["block_23", ["EXAMPLE 14.2\n"]], ["block_24", ["EXAMPLE 14.3\n"]]], "page_710": [["block_0", ["Finally, the relation between these two ion concentration expressed as p-functions is easily derived from the\nKw expression:\n"]], ["block_1", ["(b) as a base with HI\n"]], ["block_2", [" Solution \n"]], ["block_3", ["(a)\n"]], ["block_4", ["(b)\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["Write separate equations representing the reaction of\n"]], ["block_7", ["(a) as a base with HBr\n"]], ["block_8", ["(b) as an acid with OH\n"]], ["block_9", [" Answer: \n(a)\n(b)\n"]], ["block_10", [" 14.2 pH and pOH \n"]], ["block_11", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_12", ["As discussed earlier, hydronium and hydroxide ions are present both in pure water and in all aqueous\nsolutions, and their concentrations are inversely proportional as determined by the ion product of water (Kw).\nThe concentrations of these ions in a solution are often critical determinants of the solution\u2019s properties and\nthe chemical behaviors of its other solutes, and specific vocabulary has been developed to describe these\nconcentrations in relative terms. A solution is neutral if it contains equal concentrations of hydronium and\nhydroxide ions; acidic if it contains a greater concentration of hydronium ions than hydroxide ions; and basic \nif it contains a lesser concentration of hydronium ions than hydroxide ions.\n"]], ["block_13", ["A common means of expressing quantities that may span many orders of magnitude is to use a logarithmic\nscale. One such scale that is very popular for chemical concentrations and equilibrium constants is based on\nthe p-function, defined as shown where \u201cX\u201d is the quantity of interest and \u201clog\u201d is the base-10 logarithm:\n"]], ["block_14", ["The pH of a solution is therefore defined as shown here, where [H3O] is the molar concentration of hydronium\nion in the solution:\n"]], ["block_15", ["Rearranging this equation to isolate the hydronium ion molarity yields the equivalent expression:\n"]], ["block_16", ["Likewise, the hydroxide ion molarity may be expressed as a p-function, or pOH :\n"]], ["block_17", ["or\n"]], ["block_18", ["\u2022\nExplain the characterization of aqueous solutions as acidic, basic, or neutral\n"]], ["block_19", ["\u2022\nExpress hydronium and hydroxide ion concentrations on the pH and pOH scales\n"]], ["block_20", ["\u2022\nPerform calculations relating pH and pOH\n"]], ["block_21", [" 14.2 \u2022 pH and pOH \n 697 \n"]]], "page_711": [["block_0", [" 698 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", ["At 25 \u00b0C, the value of Kw is 1.0\n10, and so:\n"]], ["block_2", ["As was shown in Example 14.1, the hydronium ion molarity in pure water (or any neutral solution) is 1.0\n10M at 25 \u00b0C. The pH and pOH of a neutral solution at this temperature are therefore:\n"]], ["block_3", ["And so, at this temperature, acidic solutions are those with hydronium ion molarities greater than 1.0\n10M\n"]], ["block_4", ["and hydroxide ion molarities less than 1.0\n10M (corresponding to pH values less than 7.00 and pOH values\n"]], ["block_5", ["greater than 7.00). Basic solutions are those with hydronium ion molarities less than 1.0\n10M and\n"]], ["block_6", ["hydroxide ion molarities greater than 1.0\n10M (corresponding to pH values greater than 7.00 and pOH\n"]], ["block_7", ["values less than 7.00).\n"]], ["block_8", ["Since the autoionization constant Kw is temperature dependent, these correlations between pH values and the\nacidic/neutral/basic adjectives will be different at temperatures other than 25 \u00b0C. For example, the \u201cCheck\nYour Learning\u201d exercise accompanying Example 14.1 showed the hydronium molarity of pure water at 80 \u00b0C is\n4.9\n10M, which corresponds to pH and pOH values of:\n"]], ["block_9", ["At this temperature, then, neutral solutions exhibit pH = pOH = 6.31, acidic solutions exhibit pH less than 6.31\nand pOH greater than 6.31, whereas basic solutions exhibit pH greater than 6.31 and pOH less than 6.31. This\ndistinction can be important when studying certain processes that occur at other temperatures, such as\nenzyme reactions in warm-blooded organisms at a temperature around 36\u201340 \u00b0C. Unless otherwise noted,\nreferences to pH values are presumed to be those at 25 \u00b0C (Table 14.1).\n"]], ["block_10", ["Figure 14.2 shows the relationships between [H3O], [OH], pH, and pOH for solutions classified as acidic,\nbasic, and neutral.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", [" TABLE 14.1 \n"]], ["block_13", ["Summary of Relations for Acidic, Basic and Neutral Solutions\n"]], ["block_14", [" Classification \n Relative Ion Concentrations \n pH at 25 \u00b0C \n"]], ["block_15", ["neutral\n[H3O] = [OH]\npH = 7\n"]], ["block_16", ["acidic\n[H3O] > [OH]\npH < 7\n"]], ["block_17", ["basic\n[H3O] < [OH]\npH > 7\n"]]], "page_712": [["block_0", [{"image_0": "712_0.png", "coords": [72, 57, 540, 467]}]], ["block_1", [" FIGURE 14.2 \nThe pH and pOH scales represent concentrations of H3Oand OH, respectively. The pH and pOH\n"]], ["block_2", ["values of some common substances at 25 \u00b0C are shown in this chart.\n"]], ["block_3", [" Calculation of pH from [H 3 O + ] \n"]], ["block_4", ["What is the pH of stomach acid, a solution of HCl with a hydronium ion concentration of 1.2\n10M?\n"]], ["block_5", [" Solution \n"]], ["block_6", ["(The use of logarithms is explained in Appendix B. When taking the log of a value, keep as many decimal places\nin the result as there are significant figures in the value.)\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["Water exposed to air contains carbonic acid, H2CO3, due to the reaction between carbon dioxide and water:\n"]], ["block_9", ["EXAMPLE 14.4\n"]], ["block_10", [" 14.2 \u2022 pH and pOH \n 699 \n"]]], "page_713": [["block_0", [" 700 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", ["Air-saturated water has a hydronium ion concentration caused by the dissolved CO2 of 2.0\n10M, about\n"]], ["block_2", ["20-times larger than that of pure water. Calculate the pH of the solution at 25 \u00b0C.\n"]], ["block_3", [" Answer: \n5.70\n"]], ["block_4", [" Calculation of Hydronium Ion Concentration from pH \n"]], ["block_5", ["Calculate the hydronium ion concentration of blood, the pH of which is 7.3.\n"]], ["block_6", [" Solution \n"]], ["block_7", ["(On a calculator take the antilog, or the \u201cinverse\u201d log, of \u22127.3, or calculate 10.)\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["Calculate the hydronium ion concentration of a solution with a pH of \u22121.07.\n"]], ["block_10", [" Answer: \n12 M\n"]], ["block_11", [" Environmental Science \nNormal rainwater has a pH between 5 and 6 due to the presence of dissolved CO2 which forms carbonic acid:\n"]], ["block_12", ["Acid rain is rainwater that has a pH of less than 5, due to a variety of nonmetal oxides, including CO2, SO2, SO3,\nNO, and NO2 being dissolved in the water and reacting with it to form not only carbonic acid, but sulfuric acid\nand nitric acid. The formation and subsequent ionization of sulfuric acid are shown here:\n"]], ["block_13", ["Carbon dioxide is naturally present in the atmosphere because most organisms produce it as a waste product\nof metabolism. Carbon dioxide is also formed when fires release carbon stored in vegetation or fossil fuels.\nSulfur trioxide in the atmosphere is naturally produced by volcanic activity, but it also originates from burning\nfossil fuels, which have traces of sulfur, and from the process of \u201croasting\u201d ores of metal sulfides in metal-\nrefining processes. Oxides of nitrogen are formed in internal combustion engines where the high\ntemperatures make it possible for the nitrogen and oxygen in air to chemically combine.\n"]], ["block_14", ["Acid rain is a particular problem in industrial areas where the products of combustion and smelting are\nreleased into the air without being stripped of sulfur and nitrogen oxides. In North America and Europe until\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["EXAMPLE 14.5\n"]], ["block_17", ["HOW SCIENCES INTERCONNECT\n"]]], "page_714": [["block_0", ["the 1980s, it was responsible for the destruction of forests and freshwater lakes, when the acidity of the rain\nactually killed trees, damaged soil, and made lakes uninhabitable for all but the most acid-tolerant species.\nAcid rain also corrodes statuary and building facades that are made of marble and limestone (Figure 14.3).\nRegulations limiting the amount of sulfur and nitrogen oxides that can be released into the atmosphere by\nindustry and automobiles have reduced the severity of acid damage to both natural and manmade\nenvironments in North America and Europe. It is now a growing problem in industrial areas of China and\nIndia.\n"]], ["block_1", ["For further information on acid rain, visit this website (http://openstax.org/l/16EPA) hosted by the US\nEnvironmental Protection Agency.\n"]], ["block_2", [" FIGURE 14.3 \n(a) Acid rain makes trees more susceptible to drought and insect infestation, and depletes nutrients\n"]], ["block_3", ["in the soil. (b) It also is corrodes statues that are carved from marble or limestone. (credit a: modification of work by\nChris M Morris; credit b: modification of work by \u201cEden, Janine and Jim\u201d/Flickr)\n"]], ["block_4", [" Calculation of pOH \n"]], ["block_5", ["What are the pOH and the pH of a 0.0125-M solution of potassium hydroxide, KOH?\n"]], ["block_6", [" Solution \n"]], ["block_7", ["Potassium hydroxide is a highly soluble ionic compound and completely dissociates when dissolved in dilute\nsolution, yielding [OH] = 0.0125 M:\n"]], ["block_8", ["The pH can be found from the pOH:\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["The hydronium ion concentration of vinegar is approximately 4\n10M. What are the corresponding values\n"]], ["block_11", ["of pOH and pH?\n"]], ["block_12", [" Answer: \npOH = 11.6, pH = 2.4\n"]], ["block_13", ["The acidity of a solution is typically assessed experimentally by measurement of its pH. The pOH of a solution\nis not usually measured, as it is easily calculated from an experimentally determined pH value. The pH of a\nsolution can be directly measured using a pH meter (Figure 14.4).\n"]], ["block_14", ["EXAMPLE 14.6\n"]], ["block_15", [{"image_0": "714_0.png", "coords": [130, 183, 481, 326]}]], ["block_16", [" 14.2 \u2022 pH and pOH \n 701 \n"]]], "page_715": [["block_0", [" 702 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", [{"image_0": "715_0.png", "coords": [72, 57, 540, 325]}]], ["block_2", [" FIGURE 14.4 \n(a) A research-grade pH meter used in a laboratory can have a resolution of 0.001 pH units, an\n"]], ["block_3", ["accuracy of \u00b1 0.002 pH units, and may cost in excess of $1000. (b) A portable pH meter has lower resolution (0.01\npH units), lower accuracy (\u00b1 0.2 pH units), and a far lower price tag. (credit b: modification of work by Jacopo\nWerther)\n"]], ["block_4", ["The pH of a solution may also be visually estimated using colored indicators (Figure 14.5). The acid-base\nequilibria that enable use of these indicator dyes for pH measurements are described in a later section of this\nchapter.\n"]], ["block_5", [{"image_1": "715_1.png", "coords": [72, 429, 540, 583]}]], ["block_6", [" FIGURE 14.5 \n(a) A solution containing a dye mixture, called universal indicator, takes on different colors\n"]], ["block_7", ["depending upon its pH. (b) Convenient test strips, called pH paper, contain embedded indicator dyes that yield pH-\ndependent color changes on contact with aqueous solutions.(credit: modification of work by Sahar Atwa)\n"]], ["block_8", [" 14.3 Relative Strengths of Acids and Bases \n"]], ["block_9", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["\u2022\nAssess the relative strengths of acids and bases according to their ionization constants\n"]], ["block_12", ["\u2022\nRationalize trends in acid\u2013base strength in relation to molecular structure\n"]], ["block_13", ["\u2022\nCarry out equilibrium calculations for weak acid\u2013base systems\n"]]], "page_716": [["block_0", [" Acid and Base Ionization Constants \n"]], ["block_1", ["The relative strength of an acid or base is the extent to which it ionizes when dissolved in water. If the\nionization reaction is essentially complete, the acid or base is termed strong; if relatively little ionization\noccurs, the acid or base is weak. As will be evident throughout the remainder of this chapter, there are many\nmore weak acids and bases than strong ones. The most common strong acids and bases are listed in Figure\n14.6.\n"]], ["block_2", ["The relative strengths of acids may be quantified by measuring their equilibrium constants in aqueous\nsolutions. In solutions of the same concentration, stronger acids ionize to a greater extent, and so yield higher\nconcentrations of hydronium ions than do weaker acids. The equilibrium constant for an acid is called the\n acid-ionization constant, K a . For the reaction of an acid HA:\n"]], ["block_3", ["the acid ionization constant is written\n"]], ["block_4", ["where the concentrations are those at equilibrium. Although water is a reactant in the reaction, it is the solvent\nas well, so we do not include [H2O] in the equation. The larger the Ka of an acid, the larger the concentration of\n"]], ["block_5", ["stronger the acid. An acid is classified as \u201cstrong\u201d when it undergoes complete ionization, in which case the\nconcentration of HA is zero and the acid ionization constant is immeasurably large (Ka \u2248 \u221e). Acids that are\npartially ionized are called \u201cweak,\u201d and their acid ionization constants may be experimentally measured. A\ntable of ionization constants for weak acids is provided in Appendix H.\n"]], ["block_6", ["To illustrate this idea, three acid ionization equations and Ka values are shown below. The ionization constants\nincrease from first to last of the listed equations, indicating the relative acid strength increases in the order\nCH3CO2H < HNO2 <\n"]], ["block_7", ["Another measure of the strength of an acid is its percent ionization. The percent ionization of a weak acid is\ndefined in terms of the composition of an equilibrium mixture:\n"]], ["block_8", ["where the numerator is equivalent to the concentration of the acid's conjugate base (per stoichiometry, [A] =\n"]], ["block_9", ["and Arelative to the concentration of the nonionized acid, HA, in an equilibrium mixture, and the\n"]], ["block_10", [{"image_0": "716_0.png", "coords": [130, 146, 481, 309]}]], ["block_11", [" FIGURE 14.6 \nSome of the common strong acids and bases are listed here.\n"]], ["block_12", [" 14.3 \u2022 Relative Strengths of Acids and Bases \n 703 \n"]]], "page_717": [["block_0", [" 704 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", ["[H3O]). Unlike the Ka value, the percent ionization of a weak acid varies with the initial concentration of acid,\ntypically decreasing as concentration increases. Equilibrium calculations of the sort described later in this\nchapter can be used to confirm this behavior.\n"]], ["block_2", [" Calculation of Percent Ionization from pH \n"]], ["block_3", ["Calculate the percent ionization of a 0.125-M solution of nitrous acid (a weak acid), with a pH of 2.09.\n"]], ["block_4", [" Solution \n"]], ["block_5", ["The percent ionization for an acid is:\n"]], ["block_6", ["Converting the provided pH to hydronium ion molarity yields\n"]], ["block_7", ["Substituting this value and the provided initial acid concentration into the percent ionization equation gives\n"]], ["block_8", ["(Recall the provided pH value of 2.09 is logarithmic, and so it contains just two significant digits, limiting the\ncertainty of the computed percent ionization.)\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["Calculate the percent ionization of a 0.10-M solution of acetic acid with a pH of 2.89.\n"]], ["block_11", [" Answer: \n1.3% ionized\n"]], ["block_12", ["View the simulation (http://openstax.org/l/16AcidBase) of strong and weak acids and bases at the molecular\nlevel.\n"]], ["block_13", ["Just as for acids, the relative strength of a base is reflected in the magnitude of its base-ionization constant \n (K b ) in aqueous solutions. In solutions of the same concentration, stronger bases ionize to a greater extent, and\nso yield higher hydroxide ion concentrations than do weaker bases. A stronger base has a larger ionization\nconstant than does a weaker base. For the reaction of a base, B:\n"]], ["block_14", ["the ionization constant is written as\n"]], ["block_15", ["Inspection of the data for three weak bases presented below shows the base strength increases in the order\n"]], ["block_16", ["A table of ionization constants for weak bases appears in Appendix I. As for acids, the relative strength of a\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["LINK TO LEARNING\n"]], ["block_19", ["EXAMPLE 14.7\n"]]], "page_718": [["block_0", ["The inverse proportional relation between Ka and Kb means the stronger the acid or base, the weaker its\nconjugate partner. Figure 14.7 illustrates this relation for several conjugate acid-base pairs.\n"]], ["block_1", ["base is also reflected in its percent ionization, computed as\n"]], ["block_2", ["but will vary depending on the base ionization constant and the initial concentration of the solution.\n"]], ["block_3", [" Relative Strengths of Conjugate Acid-Base Pairs \n"]], ["block_4", ["Br\u00f8nsted-Lowry acid-base chemistry is the transfer of protons; thus, logic suggests a relation between the\nrelative strengths of conjugate acid-base pairs. The strength of an acid or base is quantified in its ionization\nconstant, Ka or Kb, which represents the extent of the acid or base ionization reaction. For the conjugate acid-\nbase pair HA / A, ionization equilibrium equations and ionization constant expressions are\n"]], ["block_5", ["Adding these two chemical equations yields the equation for the autoionization for water:\n"]], ["block_6", ["As discussed in another chapter on equilibrium, the equilibrium constant for a summed reaction is equal to\nthe mathematical product of the equilibrium constants for the added reactions, and so\n"]], ["block_7", ["This equation states the relation between ionization constants for any conjugate acid-base pair, namely, their\nmathematical product is equal to the ion product of water, Kw. By rearranging this equation, a reciprocal\nrelation between the strengths of a conjugate acid-base pair becomes evident:\n"]], ["block_8", [{"image_0": "718_0.png", "coords": [72, 475, 540, 637]}]], ["block_9", [" FIGURE 14.7 \nRelative strengths of several conjugate acid-base pairs are shown.\n"]], ["block_10", [" 14.3 \u2022 Relative Strengths of Acids and Bases \n 705 \n"]]], "page_719": [["block_0", [" 706 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", [{"image_0": "719_0.png", "coords": [72, 57, 540, 477]}]], ["block_2", [" FIGURE 14.8 \nThis figure shows strengths of conjugate acid-base pairs relative to the strength of water as the\n"]], ["block_3", ["reference substance.\n"]], ["block_4", ["The listing of conjugate acid\u2013base pairs shown in Figure 14.8 is arranged to show the relative strength of each\nspecies as compared with water, whose entries are highlighted in each of the table\u2019s columns. In the acid\ncolumn, those species listed below water are weaker acids than water. These species do not undergo acid\nionization in water; they are not Bronsted-Lowry acids. All the species listed above water are stronger acids,\ntransferring protons to water to some extent when dissolved in an aqueous solution to generate hydronium\nions. Species above water but below hydronium ion are weak acids, undergoing partial acid ionization, wheres\nthose above hydronium ion are strong acids that are completely ionized in aqueous solution.\n"]], ["block_5", ["If all these strong acids are completely ionized in water, why does the column indicate they vary in strength,\nwith nitric acid being the weakest and perchloric acid the strongest? Notice that the sole acid species present\nin an aqueous solution of any strong acid is H3O(aq), meaning that hydronium ion is the strongest acid that\nmay exist in water; any stronger acid will react completely with water to generate hydronium ions. This limit\non the acid strength of solutes in a solution is called a leveling effect . To measure the differences in acid\nstrength for \u201cstrong\u201d acids, the acids must be dissolved in a solvent that is less basic than water. In such\nsolvents, the acids will be \u201cweak,\u201d and so any differences in the extent of their ionization can be determined.\nFor example, the binary hydrogen halides HCl, HBr, and HI are strong acids in water but weak acids in ethanol\n(strength increasing HCl < HBr < HI).\n"]], ["block_6", [" Access for free at openstax.org \n"]]], "page_720": [["block_0", ["Kb for\nis given in this section as 2.17\n10. The conjugate acid of\nis HNO2; Ka for HNO2 can be\n"]], ["block_1", ["The right column of Figure 14.8 lists a number of substances in order of increasing base strength from top to\nbottom. Following the same logic as for the left column, species listed above water are weaker bases and so\nthey don\u2019t undergo base ionization when dissolved in water. Species listed between water and its conjugate\nbase, hydroxide ion, are weak bases that partially ionize. Species listed below hydroxide ion are strong bases\nthat completely ionize in water to yield hydroxide ions (i.e., they are leveled to hydroxide). A comparison of the\nacid and base columns in this table supports the reciprocal relation between the strengths of conjugate acid-\nbase pairs. For example, the conjugate bases of the strong acids (top of table) are all of negligible strength. A\nstrong acid exhibits an immeasurably large Ka, and so its conjugate base will exhibit a Kb that is essentially\nzero:\n"]], ["block_2", ["A similar approach can be used to support the observation that conjugate acids of strong bases (Kb \u2248 \u221e) are of\nnegligible strength (Ka \u2248 0).\n"]], ["block_3", [" Calculating Ionization Constants for Conjugate Acid-Base Pairs \n"]], ["block_4", ["Use the Kb for the nitrite ion,\nto calculate the Ka for its conjugate acid.\n"]], ["block_5", [" Solution \n"]], ["block_6", ["calculated using the relationship:\n"]], ["block_7", ["Solving for Ka yields\n"]], ["block_8", ["This answer can be verified by finding the Ka for HNO2 in Appendix H.\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["Determine the relative acid strengths of\nand HCN by comparing their ionization constants. The\n"]], ["block_11", ["ionization constant of HCN is given in Appendix H as 4.9\n10. The ionization constant of\nis not\n"]], ["block_12", ["listed, but the ionization constant of its conjugate base, NH3, is listed as 1.8\n10.\n"]], ["block_13", [" Answer: \n"]], ["block_14", [" Acid-Base Equilibrium Calculations \n"]], ["block_15", ["The chapter on chemical equilibria introduced several types of equilibrium calculations and the various\nmathematical strategies that are helpful in performing them. These strategies are generally useful for\nequilibrium systems regardless of chemical reaction class, and so they may be effectively applied to acid-base\nequilibrium problems. This section presents several example exercises involving equilibrium calculations for\nacid-base systems.\n"]], ["block_16", ["EXAMPLE 14.8\n"]], ["block_17", ["is the slightly stronger acid (Ka for\n= 5.6\n10).\n"]], ["block_18", ["\u221e\n"]], ["block_19", ["\u221e\n"]], ["block_20", [" 14.3 \u2022 Relative Strengths of Acids and Bases \n 707 \n"]]], "page_721": [["block_0", [" 708 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", [{"image_0": "721_0.png", "coords": [72, 57, 423, 324]}]], ["block_2", [{"image_1": "721_1.png", "coords": [72, 327, 306, 461]}]], ["block_3", [" Determination of K a from Equilibrium Concentrations \n"]], ["block_4", ["Acetic acid is the principal ingredient in vinegar (Figure 14.9) that provides its sour taste. At equilibrium, a\nsolution contains [CH3CO2H] = 0.0787 M and\nWhat is the value of Ka for\n"]], ["block_5", ["acetic acid?\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", ["EXAMPLE 14.9\n"]]], "page_722": [["block_0", [" Answer: \nKa for\n= 1.2\n10\n"]], ["block_1", [" Solution \n"]], ["block_2", ["The relevant equilibrium equation and its equilibrium constant expression are shown below. Substitution of\nthe provided equilibrium concentrations permits a straightforward calculation of the Ka for acetic acid.\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["The\nion, weak acid used in some household cleansers:\n"]], ["block_5", ["What is the acid ionization constant for this weak acid if an equilibrium mixture has the following\ncomposition:\n= 0.027 M;\nand\n"]], ["block_6", [" Determination of K b from Equilibrium Concentrations \n"]], ["block_7", ["Caffeine, C8H10N4O2 is a weak base. What is the value of Kb for caffeine if a solution at equilibrium has\n[C8H10N4O2] = 0.050 M,\n= 5.0\n10M, and [OH] = 2.5\n10M?\n"]], ["block_8", [" Solution \n"]], ["block_9", ["The relevant equilibrium equation and its equilibrium constant expression are shown below. Substitution of\nthe provided equilibrium concentrations permits a straightforward calculation of the Kb for caffeine.\n"]], ["block_10", [" FIGURE 14.9 \nVinegar contains acetic acid, a weak acid. (credit: modification of work by \u201cHomeSpot HQ\u201d/Flickr)\n"]], ["block_11", ["EXAMPLE 14.10\n"]], ["block_12", [{"image_0": "722_0.png", "coords": [189, 57, 423, 280]}]], ["block_13", [" 14.3 \u2022 Relative Strengths of Acids and Bases \n 709 \n"]]], "page_723": [["block_0", [" 710 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", ["Kb for\n"]], ["block_2", ["The nitrous acid concentration provided is a formal concentration, one that does not account for any chemical\nequilibria that may be established in solution. Such concentrations are treated as \u201cinitial\u201d values for\nequilibrium calculations using the ICE table approach. Notice the initial value of hydronium ion is listed as\napproximately zero because a small concentration of H3Ois present (1 \u00d7 10M) due to the autoprotolysis of\nwater. In many cases, such as all the ones presented in this chapter, this concentration is much less than that\ngenerated by ionization of the acid (or base) in question and may be neglected.\n"]], ["block_3", [" Answer: \nKb = 1.8\n10\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["What is the equilibrium constant for the ionization of the\nion, a weak base\n"]], ["block_6", ["if the composition of an equilibrium mixture is as follows: [OH] = 1.3\n10M;\nand\n"]], ["block_7", [" Answer: \n"]], ["block_8", [" Determination of K a or K b from pH \n"]], ["block_9", ["The pH of a 0.0516-M solution of nitrous acid, HNO2, is 2.34. What is its Ka?\n"]], ["block_10", [" Solution \n"]], ["block_11", ["The pH provided is a logarithmic measure of the hydronium ion concentration resulting from the acid\nionization of the nitrous acid, and so it represents an \u201cequilibrium\u201d value for the ICE table:\n"]], ["block_12", ["The ICE table for this system is then\n"]], ["block_13", [{"image_0": "723_0.png", "coords": [72, 445, 432, 539]}]], ["block_14", ["Finally, calculate the value of the equilibrium constant using the data in the table:\n"]], ["block_15", [" Check Your Learning. \n"]], ["block_16", ["The pH of a solution of household ammonia, a 0.950-M solution of NH3, is 11.612. What is Kb for NH3.\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["EXAMPLE 14.11\n"]]], "page_724": [["block_0", [" Calculating Equilibrium Concentrations in a Weak Acid Solution \n"]], ["block_1", ["Formic acid, HCO2H, is one irritant that causes the body\u2019s reaction to some ant bites and stings (Figure 14.10).\n"]], ["block_2", ["What is the concentration of hydronium ion and the pH of a 0.534-M solution of formic acid?\n"]], ["block_3", [" Solution \n"]], ["block_4", ["The ICE table for this system is\n"]], ["block_5", [{"image_0": "724_0.png", "coords": [72, 355, 493, 451]}]], ["block_6", ["Substituting the equilibrium concentration terms into the Ka expression gives\n"]], ["block_7", ["The relatively large initial concentration and small equilibrium constant permits the simplifying assumption\nthat x will be much lesser than 0.534, and so the equation becomes\n"]], ["block_8", ["Solving the equation for x yields\n"]], ["block_9", ["EXAMPLE 14.12\n"]], ["block_10", [" FIGURE 14.10 \nThe pain of some ant bites and stings is caused by formic acid. (credit: John Tann)\n"]], ["block_11", [{"image_1": "724_1.png", "coords": [189, 125, 423, 256]}]], ["block_12", [" 14.3 \u2022 Relative Strengths of Acids and Bases \n 711 \n"]]], "page_725": [["block_0", [" 712 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", ["To check the assumption that x is small compared to 0.534, its relative magnitude can be estimated:\n"]], ["block_2", ["Because x is less than 5% of the initial concentration, the assumption is valid.\n"]], ["block_3", ["As defined in the ICE table, x is equal to the equilibrium concentration of hydronium ion:\n"]], ["block_4", ["Finally, the pH is calculated to be\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["Only a small fraction of a weak acid ionizes in aqueous solution. What is the percent ionization of a 0.100-M\nsolution of acetic acid, CH3CO2H?\n"]], ["block_7", [" Answer: \npercent ionization = 1.3%\n"]], ["block_8", [" Calculating Equilibrium Concentrations in a Weak Base Solution \n"]], ["block_9", ["Find the concentration of hydroxide ion, the pOH, and the pH of a 0.25-M solution of trimethylamine, a weak\nbase:\n"]], ["block_10", [" Solution \n"]], ["block_11", ["The ICE table for this system is\n"]], ["block_12", [{"image_0": "725_0.png", "coords": [72, 487, 432, 581]}]], ["block_13", ["Substituting the equilibrium concentration terms into the Kb expression gives\n"]], ["block_14", ["Assuming x << 0.25 and solving for x yields\n"]], ["block_15", ["This value is less than 5% of the initial concentration (0.25), so the assumption is justified.\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["EXAMPLE 14.13\n"]]], "page_726": [["block_0", ["As defined in the ICE table, x is equal to the equilibrium concentration of hydroxide ion:\n"]], ["block_1", ["The pOH is calculated to be\n"]], ["block_2", ["Using the relation introduced in the previous section of this chapter:\n"]], ["block_3", ["permits the computation of pH:\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["Calculate the hydroxide ion concentration and the percent ionization of a 0.0325-M solution of ammonia, a\nweak base with a Kb of 1.76\n10.\n"]], ["block_6", [" Answer: \n7.56\n10M, 2.33%\n"]], ["block_7", ["In some cases, the strength of the weak acid or base and its formal (initial) concentration result in an\nappreciable ionization. Though the ICE strategy remains effective for these systems, the algebra is a bit more\ninvolved because the simplifying assumption that x is negligible cannot be made. Calculations of this sort are\ndemonstrated in Example 14.14 below.\n"]], ["block_8", [" Calculating Equilibrium Concentrations without Simplifying Assumptions \n"]], ["block_9", ["Sodium bisulfate, NaHSO4, is used in some household cleansers as a source of the\nion, a weak acid.\n"]], ["block_10", ["What is the pH of a 0.50-M solution of\n"]], ["block_11", [" Solution \n"]], ["block_12", ["The ICE table for this system is\n"]], ["block_13", [{"image_0": "726_0.png", "coords": [72, 570, 433, 687]}]], ["block_14", ["Substituting the equilibrium concentration terms into the Ka expression gives\n"]], ["block_15", ["EXAMPLE 14.14\n"]], ["block_16", [" 14.3 \u2022 Relative Strengths of Acids and Bases \n 713 \n"]]], "page_727": [["block_0", [" 714 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", ["If the assumption that x << 0.5 is made, simplifying and solving the above equation yields\n"]], ["block_2", ["This value of x is clearly not significantly less than 0.50 M; rather, it is approximately 15% of the initial\nconcentration:\nWhen we check the assumption, we calculate:\n"]], ["block_3", ["Because the simplifying assumption is not valid for this system, the equilibrium constant expression is solved\nas follows:\n"]], ["block_4", ["Rearranging this equation yields\n"]], ["block_5", ["Writing the equation in quadratic form gives\n"]], ["block_6", ["Solving for the two roots of this quadratic equation results in a negative value that may be discarded as\nphysically irrelevant and a positive value equal to x. As defined in the ICE table, x is equal to the hydronium\nconcentration.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["Calculate the pH in a 0.010-M solution of caffeine, a weak base:\n"]], ["block_9", [" Answer: \npH 11.16\n"]], ["block_10", [" Effect of Molecular Structure on Acid-Base Strength \n"]], ["block_11", [" Binary Acids and Bases \nIn the absence of any leveling effect, the acid strength of binary compounds of hydrogen with nonmetals (A)\nincreases as the H-A bond strength decreases down a group in the periodic table. For group 17, the order of\nincreasing acidity is HF < HCl < HBr < HI. Likewise, for group 16, the order of increasing acid strength is H2O <\nH2S < H2Se < H2Te.\n"]], ["block_12", [" Access for free at openstax.org \n"]]], "page_728": [["block_0", ["Across a row in the periodic table, the acid strength of binary hydrogen compounds increases with increasing\nelectronegativity of the nonmetal atom because the polarity of the H-A bond increases. Thus, the order of\nincreasing acidity (for removal of one proton) across the second row is CH4 < NH3 < H2O < HF; across the third\nrow, it is SiH4 < PH3 < H2S < HCl (see Figure 14.11).\n"]], ["block_1", [" Ternary Acids and Bases \n"]], ["block_2", ["Ternary compounds composed of hydrogen, oxygen, and some third element (\u201cE\u201d) may be structured as\ndepicted in the image below. In these compounds, the central E atom is bonded to one or more O atoms, and at\nleast one of the O atoms is also bonded to an H atom, corresponding to the general molecular formula\nOmE(OH)n. These compounds may be acidic, basic, or amphoteric depending on the properties of the central E\natom. Examples of such compounds include sulfuric acid, O2S(OH)2, sulfurous acid, OS(OH)2, nitric acid,\nO2NOH, perchloric acid, O3ClOH, aluminum hydroxide, Al(OH)3, calcium hydroxide, Ca(OH)2, and potassium\nhydroxide, KOH:\n"]], ["block_3", [{"image_0": "728_0.png", "coords": [72, 472, 189, 521]}]], ["block_4", ["If the central atom, E, has a low electronegativity, its attraction for electrons is low. Little tendency exists for the\ncentral atom to form a strong covalent bond with the oxygen atom, and bond a between the element and\noxygen is more readily broken than bond b between oxygen and hydrogen. Hence bond a is ionic, hydroxide\nions are released to the solution, and the material behaves as a base\u2014this is the case with Ca(OH)2 and KOH.\nLower electronegativity is characteristic of the more metallic elements; hence, the metallic elements form\nionic hydroxides that are by definition basic compounds.\n"]], ["block_5", ["If, on the other hand, the atom E has a relatively high electronegativity, it strongly attracts the electrons it\nshares with the oxygen atom, making bond a relatively strongly covalent. The oxygen-hydrogen bond, bond b,\nis thereby weakened because electrons are displaced toward E. Bond b is polar and readily releases hydrogen\nions to the solution, so the material behaves as an acid. High electronegativities are characteristic of the more\nnonmetallic elements. Thus, nonmetallic elements form covalent compounds containing acidic \u2212OH groups\nthat are called oxyacids .\n"]], ["block_6", ["Increasing the oxidation number of the central atom E also increases the acidity of an oxyacid because this\nincreases the attraction of E for the electrons it shares with oxygen and thereby weakens the O-H bond.\nSulfuric acid, H2SO4, or O2S(OH)2 (with a sulfur oxidation number of +6), is more acidic than sulfurous acid,\n"]], ["block_7", [{"image_1": "728_1.png", "coords": [130, 114, 481, 336]}]], ["block_8", [" FIGURE 14.11 \nThe figure shows trends in the strengths of binary acids and bases.\n"]], ["block_9", [" 14.3 \u2022 Relative Strengths of Acids and Bases \n 715 \n"]]], "page_729": [["block_0", [" 716 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", ["H2SO3, or OS(OH)2 (with a sulfur oxidation number of +4). Likewise nitric acid, HNO3, or O2NOH (N oxidation\nnumber = +5), is more acidic than nitrous acid, HNO2, or ONOH (N oxidation number = +3). In each of these\npairs, the oxidation number of the central atom is larger for the stronger acid (Figure 14.12).\n"]], ["block_2", ["Hydroxy compounds of elements with intermediate electronegativities and relatively high oxidation numbers\n(for example, elements near the diagonal line separating the metals from the nonmetals in the periodic table)\nare usually amphoteric. This means that the hydroxy compounds act as acids when they react with strong\nbases and as bases when they react with strong acids. The amphoterism of aluminum hydroxide, which\ncommonly exists as the hydrate Al(H2O)3(OH)3, is reflected in its solubility in both strong acids and strong\nbases. In strong bases, the relatively insoluble hydrated aluminum hydroxide, Al(H2O)3(OH)3, is converted into\nthe soluble ion,\nby reaction with hydroxide ion:\n"]], ["block_3", ["In this reaction, a proton is transferred from one of the aluminum-bound H2O molecules to a hydroxide ion in\nsolution. The Al(H2O)3(OH)3 compound thus acts as an acid under these conditions. On the other hand, when\ndissolved in strong acids, it is converted to the soluble ion\nby reaction with hydronium ion:\n"]], ["block_4", ["In this case, protons are transferred from hydronium ions in solution to Al(H2O)3(OH)3, and the compound\nfunctions as a base.\n"]], ["block_5", [" 14.4 Hydrolysis of Salts \n"]], ["block_6", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_7", [" Salts with Acidic Ions \n"]], ["block_8", ["Salts are ionic compounds composed of cations and anions, either of which may be capable of undergoing an\nacid or base ionization reaction with water. Aqueous salt solutions, therefore, may be acidic, basic, or neutral,\ndepending on the relative acid-base strengths of the salt's constituent ions. For example, dissolving\nammonium chloride in water results in its dissociation, as described by the equation\n"]], ["block_9", ["The ammonium ion is the conjugate acid of the base ammonia, NH3; its acid ionization (or acid hydrolysis)\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["\u2022\nPredict whether a salt solution will be acidic, basic, or neutral\n"]], ["block_12", ["\u2022\nCalculate the concentrations of the various species in a salt solution\n"]], ["block_13", ["\u2022\nDescribe the acid ionization of hydrated metal ions\n"]], ["block_14", [" FIGURE 14.12 \nAs the oxidation number of the central atom E increases, the acidity also increases.\n"]], ["block_15", [{"image_0": "729_0.png", "coords": [130, 101, 481, 301]}]]], "page_730": [["block_0", ["reaction is represented by\n"]], ["block_1", ["Since ammonia is a weak base, Kb is measurable and Ka > 0 (ammonium ion is a weak acid).\n"]], ["block_2", ["The chloride ion is the conjugate base of hydrochloric acid, and so its base ionization (or base hydrolysis)\nreaction is represented by\n"]], ["block_3", ["Since HCl is a strong acid, Ka is immeasurably large and Kb \u2248 0 (chloride ions don\u2019t undergo appreciable\nhydrolysis).\n"]], ["block_4", ["Thus, dissolving ammonium chloride in water yields a solution of weak acid cations (\n) and inert anions\n"]], ["block_5", ["(Cl), resulting in an acidic solution.\n"]], ["block_6", [" Calculating the pH of an Acidic Salt Solution \n"]], ["block_7", ["Aniline is an amine that is used to manufacture dyes. It is isolated as anilinium chloride,\na salt\n"]], ["block_8", ["prepared by the reaction of the weak base aniline and hydrochloric acid. What is the pH of a 0.233 M solution\nof anilinium chloride\n"]], ["block_9", [" Solution \n"]], ["block_10", ["The Ka for anilinium ion is derived from the Kb for its conjugate base, aniline (see Appendix H):\n"]], ["block_11", ["Using the provided information, an ICE table for this system is prepared:\n"]], ["block_12", [{"image_0": "730_0.png", "coords": [72, 424, 493, 520]}]], ["block_13", ["Substituting these equilibrium concentration terms into the Ka expression gives\n"]], ["block_14", ["Assuming x << 0.233, the equation is simplified and solved for x:\n"]], ["block_15", ["The ICE table defines x as the hydronium ion molarity, and so the pH is computed as\n"]], ["block_16", [" Check Your Learning \n"]], ["block_17", ["What is the hydronium ion concentration in a 0.100-M solution of ammonium nitrate, NH4NO3, a salt\n"]], ["block_18", ["EXAMPLE 14.15\n"]], ["block_19", [" 14.4 \u2022 Hydrolysis of Salts \n 717 \n"]]], "page_731": [["block_0", [" 718 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", ["hydrolysis) reaction is represented by\n"]], ["block_2", ["composed of the ions\nand\nWhich is the stronger acid\nor\n"]], ["block_3", [" Answer: \n[H3O] = 7.5\n10M;\nis the stronger acid.\n"]], ["block_4", [" Salts with Basic Ions \n"]], ["block_5", ["As another example, consider dissolving sodium acetate in water:\n"]], ["block_6", ["The sodium ion does not undergo appreciable acid or base ionization and has no effect on the solution pH.\nThis may seem obvious from the ion's formula, which indicates no hydrogen or oxygen atoms, but some\ndissolved metal ions function as weak acids, as addressed later in this section.\n"]], ["block_7", ["The acetate ion,\nis the conjugate base of acetic acid, CH3CO2H, and so its base ionization (or base\n"]], ["block_8", ["Because acetic acid is a weak acid, its Ka is measurable and Kb > 0 (acetate ion is a weak base).\n"]], ["block_9", ["Dissolving sodium acetate in water yields a solution of inert cations (Na) and weak base anions\nresulting in a basic solution.\n"]], ["block_10", [" Equilibrium in a Solution of a Salt of a Weak Acid and a Strong Base \n"]], ["block_11", ["Determine the acetic acid concentration in a solution with\nand [OH] = 2.5\n10M at\n"]], ["block_12", ["equilibrium. The reaction is:\n"]], ["block_13", [" Solution \n"]], ["block_14", ["The provided equilibrium concentrations and a value for the equilibrium constant will permit calculation of\nthe missing equilibrium concentration. The process in question is the base ionization of acetate ion, for which\n"]], ["block_15", ["Substituting the available values into the Kb expression gives\n"]], ["block_16", ["Solving the above equation for the acetic acid molarity yields [CH3CO2H] = 1.1\n10M.\n"]], ["block_17", [" Check Your Learning \n"]], ["block_18", ["What is the pH of a 0.083-M solution of NaCN?\n"]], ["block_19", [" Answer: \n11.11\n"]], ["block_20", [" Salts with Acidic and Basic Ions \n"]], ["block_21", ["Some salts are composed of both acidic and basic ions, and so the pH of their solutions will depend on the\n"]], ["block_22", [" Access for free at openstax.org \n"]], ["block_23", ["EXAMPLE 14.16\n"]]], "page_732": [["block_0", ["relative strengths of these two species. Likewise, some salts contain a single ion that is amphiprotic, and so the\nrelative strengths of this ion\u2019s acid and base character will determine its effect on solution pH. For both types\nof salts, a comparison of the Ka and Kb values allows prediction of the solution\u2019s acid-base status, as illustrated\nin the following example exercise.\n"]], ["block_1", [" Determining the Acidic or Basic Nature of Salts \n"]], ["block_2", ["Determine whether aqueous solutions of the following salts are acidic, basic, or neutral:\n"]], ["block_3", ["(a) KBr\n"]], ["block_4", ["(b) NaHCO3\n"]], ["block_5", ["(c) Na2HPO4\n"]], ["block_6", ["(d) NH4F\n"]], ["block_7", [" Solution \n"]], ["block_8", ["Consider each of the ions separately in terms of its effect on the pH of the solution, as shown here:\n"]], ["block_9", ["(a) The Kcation is inert and will not affect pH. The bromide ion is the conjugate base of a strong acid, and so it\nis of negligible base strength (no appreciable base ionization). The solution is neutral.\n"]], ["block_10", ["(b) The Nacation is inert and will not affect the pH of the solution; while the\nanion is amphiprotic.\n"]], ["block_11", ["The Ka of\nis 4.7\n10,and its Kb is\n"]], ["block_12", ["Since Kb >> Ka, the solution is basic.\n"]], ["block_13", ["(c) The Nacation is inert and will not affect the pH of the solution, while the\nanion is amphiprotic.\n"]], ["block_14", ["The Ka of\nis 4.2\n10,\n"]], ["block_15", ["and its Kb is\nBecause Kb >> Ka, the solution is basic.\n"]], ["block_16", ["(d) The\nion is acidic (see above discussion) and the Fion is basic (conjugate base of the weak acid HF).\n"]], ["block_17", ["Comparing the two ionization constants: Ka of\nis 5.6\n10and the Kb of Fis 1.6\n10, so the\n"]], ["block_18", ["solution is acidic, since Ka > Kb.\n"]], ["block_19", [" Check Your Learning \n"]], ["block_20", ["Determine whether aqueous solutions of the following salts are acidic, basic, or neutral:\n"]], ["block_21", ["(a) K2CO3\n"]], ["block_22", ["(b) CaCl2\n"]], ["block_23", ["(c) KH2PO4\n"]], ["block_24", ["(d) (NH4)2CO3\n"]], ["block_25", [" Answer: \n(a) basic; (b) neutral; (c) acidic; (d) basic\n"]], ["block_26", [" The Ionization of Hydrated Metal Ions \n"]], ["block_27", ["Unlike the group 1 and 2 metal ions of the preceding examples (Na, Ca, etc.), some metal ions function as\nacids in aqueous solutions. These ions are not just loosely solvated by water molecules when dissolved, instead\nthey are covalently bonded to a fixed number of water molecules to yield a complex ion (see chapter on\ncoordination chemistry). As an example, the dissolution of aluminum nitrate in water is typically represented\nas\n"]], ["block_28", ["EXAMPLE 14.17\n"]], ["block_29", [" 14.4 \u2022 Hydrolysis of Salts \n 719 \n"]]], "page_733": [["block_0", [" 720 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", ["However, the aluminum(III) ion actually reacts with six water molecules to form a stable complex ion, and so\nthe more explicit representation of the dissolution process is\n"]], ["block_2", ["As shown in Figure 14.13, the\nions involve bonds between a central Al atom and the O atoms of\n"]], ["block_3", ["the six water molecules. Consequently, the bonded water molecules' O\u2013H bonds are more polar than in\nnonbonded water molecules, making the bonded molecules more prone to donation of a hydrogen ion:\n"]], ["block_4", ["The conjugate base produced by this process contains five other bonded water molecules capable of acting as\nacids, and so the sequential or step-wise transfer of protons is possible as depicted in few equations below:\n"]], ["block_5", ["This is an example of a polyprotic acid, the topic of discussion in a later section of this chapter.\n"]], ["block_6", ["Aside from the alkali metals (group 1) and some alkaline earth metals (group 2), most other metal ions will\nundergo acid ionization to some extent when dissolved in water. The acid strength of these complex ions\ntypically increases with increasing charge and decreasing size of the metal ions. The first-step acid ionization\nequations for a few other acidic metal ions are shown below:\n"]], ["block_7", [" Hydrolysis of [Al(H 2 O) 6 ] 3+ \n"]], ["block_8", ["Calculate the pH of a 0.10-M solution of aluminum chloride, which dissolves completely to give the hydrated\naluminum ion\nin solution.\n"]], ["block_9", [" Solution \n"]], ["block_10", ["The equation for the reaction and Ka are:\n"]], ["block_11", ["An ICE table with the provided information is\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", [" FIGURE 14.13 \nWhen an aluminum ion reacts with water, the hydrated aluminum ion becomes a weak acid.\n"]], ["block_14", ["EXAMPLE 14.18\n"]], ["block_15", [{"image_0": "733_0.png", "coords": [130, 302, 481, 421]}]]], "page_734": [["block_0", [{"image_0": "734_0.png", "coords": [72, 57, 423, 152]}]], ["block_1", ["Substituting the expressions for the equilibrium concentrations into the equation for the ionization constant\nyields:\n"]], ["block_2", ["Assuming x << 0.10 and solving the simplified equation gives:\n"]], ["block_3", ["The ICE table defined x as equal to the hydronium ion concentration, and so the pH is calculated to be\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["What is\nin a 0.15-M solution of Al(NO3)3 that contains enough of the strong acid HNO3 to\n"]], ["block_6", ["bring [H3O] to 0.10 M?\n"]], ["block_7", [" Answer: \n2.1\n10M\n"]], ["block_8", [" 14.5 Polyprotic Acids \n"]], ["block_9", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_10", ["Acids are classified by the number of protons per molecule that they can give up in a reaction. Acids such as\nHCl, HNO3, and HCN that contain one ionizable hydrogen atom in each molecule are called monoprotic acids .\nTheir reactions with water are:\n"]], ["block_11", ["Even though it contains four hydrogen atoms, acetic acid, CH3CO2H, is also monoprotic because only the\nhydrogen atom from the carboxyl group (COOH) reacts with bases:\n"]], ["block_12", ["\u2022\nExtend previously introduced equilibrium concepts to acids and bases that may donate or accept more than one\nproton\n"]], ["block_13", [" 14.5 \u2022 Polyprotic Acids \n 721 \n"]]], "page_735": [["block_0", [" 722 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", [{"image_0": "735_0.png", "coords": [72, 57, 540, 140]}]], ["block_2", ["Similarly, monoprotic bases are bases that will accept a single proton.\n"]], ["block_3", [" Diprotic acids contain two ionizable hydrogen atoms per molecule; ionization of such acids occurs in two\nsteps. The first ionization always takes place to a greater extent than the second ionization. For example,\nsulfuric acid, a strong acid, ionizes as follows:\n"]], ["block_4", ["This stepwise ionization process occurs for all polyprotic acids. Carbonic acid, H2CO3, is an example of a weak\ndiprotic acid. The first ionization of carbonic acid yields hydronium ions and bicarbonate ions in small\namounts.\n"]], ["block_5", ["The bicarbonate ion can also act as an acid. It ionizes and forms hydronium ions and carbonate ions in even\nsmaller quantities.\n"]], ["block_6", ["solution. This means that little of the\nformed by the ionization of H2CO3 ionizes to give hydronium\n"]], ["block_7", ["ions (and carbonate ions), and the concentrations of H3Oand\nare practically equal in a pure aqueous\n"]], ["block_8", ["solution of H2CO3.\n"]], ["block_9", ["If the first ionization constant of a weak diprotic acid is larger than the second by a factor of at least 20, it is\nappropriate to treat the first ionization separately and calculate concentrations resulting from it before\ncalculating concentrations of species resulting from subsequent ionization. This approach is demonstrated in\nthe following example exercise.\n"]], ["block_10", [" Ionization of a Diprotic Acid \n"]], ["block_11", ["\u201cCarbonated water\u201d contains a palatable amount of dissolved carbon dioxide. The solution is acidic because\nCO2 reacts with water to form carbonic acid, H2CO3. What are\nand\nin a saturated\n"]], ["block_12", ["solution of CO2 with an initial [H2CO3] = 0.033 M?\n"]], ["block_13", [" Solution \n"]], ["block_14", ["As indicated by the ionization constants, H2CO3 is a much stronger acid than\nso the stepwise\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["EXAMPLE 14.19\n"]], ["block_17", ["is larger than\nby a factor of 10, so H2CO3 is the dominant producer of hydronium ion in the\n"]]], "page_736": [["block_0", ["ionization reactions may be treated separately.\n"]], ["block_1", ["The first ionization reaction is\n"]], ["block_2", ["Using provided information, an ICE table for this first step is prepared:\n"]], ["block_3", [{"image_0": "736_0.png", "coords": [72, 146, 503, 242]}]], ["block_4", ["Substituting the equilibrium concentrations into the equilibrium equation gives\n"]], ["block_5", ["Assuming x << 0.033 and solving the simplified equation yields\n"]], ["block_6", ["The ICE table defined x as equal to the bicarbonate ion molarity and the hydronium ion molarity:\n"]], ["block_7", ["Using the bicarbonate ion concentration computed above, the second ionization is subjected to a similar\nequilibrium calculation:\n"]], ["block_8", ["To summarize: at equilibrium [H2CO3] = 0.033 M;\n= 1.2\n10;\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["The concentration of H2S in a saturated aqueous solution at room temperature is approximately 0.1 M.\nCalculate\n[HS], and [S] in the solution:\n"]], ["block_11", [" Answer: \n[H2S] = 0.1 M;\n= [HS] = 0.000094 M; [S] = 1\n10M\n"]], ["block_12", [" 14.5 \u2022 Polyprotic Acids \n 723 \n"]]], "page_737": [["block_0", [" 724 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", ["A triprotic acid is an acid that has three ionizable H atoms. Phosphoric acid is one example:\n"]], ["block_2", ["As for the diprotic acid examples, each successive ionization reaction is less extensive than the former,\nreflected in decreasing values for the stepwise acid ionization constants. This is a general characteristic of\npolyprotic acids and successive ionization constants often differ by a factor of about 10to 10.\n"]], ["block_3", ["This set of three dissociation reactions may appear to make calculations of equilibrium concentrations in a\nsolution of H3PO4 complicated. However, because the successive ionization constants differ by a factor of 10\n"]], ["block_4", ["to 10, large differences exist in the small changes in concentration accompanying the ionization reactions.\nThis allows the use of math-simplifying assumptions and processes, as demonstrated in the examples above.\n"]], ["block_5", ["Polyprotic bases are capable of accepting more than one hydrogen ion. The carbonate ion is an example of a\n diprotic base , because it can accept two protons, as shown below. Similar to the case for polyprotic acids, note\nthe ionization constants decrease with ionization step. Likewise, equilibrium calculations involving polyprotic\nbases follow the same approaches as those for polyprotic acids.\n"]], ["block_6", [" 14.6 Buffers \n"]], ["block_7", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_8", ["A solution containing appreciable amounts of a weak conjugate acid-base pair is called a buffer solution, or a\n buffer . Buffer solutions resist a change in pH when small amounts of a strong acid or a strong base are added\n(Figure 14.14). A solution of acetic acid and sodium acetate (CH3COOH + CH3COONa) is an example of a buffer\nthat consists of a weak acid and its salt. An example of a buffer that consists of a weak base and its salt is a\nsolution of ammonia and ammonium chloride (NH3(aq) + NH4Cl(aq)).\n"]], ["block_9", [" FIGURE 14.14 \n(a) The unbuffered solution on the left and the buffered solution on the right have the same pH (pH\n"]], ["block_10", ["8); they are basic, showing the yellow color of the indicator methyl orange at this pH. (b) After the addition of 1 mL of\na 0.01-M HCl solution, the buffered solution has not detectably changed its pH but the unbuffered solution has\nbecome acidic, as indicated by the change in color of the methyl orange, which turns red at a pH of about 4. (credit:\nmodification of work by Mark Ott)\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["\u2022\nDescribe the composition and function of acid\u2013base buffers\n"]], ["block_13", ["\u2022\nCalculate the pH of a buffer before and after the addition of added acid or base\n"]], ["block_14", [{"image_0": "737_0.png", "coords": [130, 514, 481, 639]}]]], "page_738": [["block_0", [" How Buffers Work \n"]], ["block_1", ["To illustrate the function of a buffer solution, consider a mixture of roughly equal amounts of acetic acid and\nsodium acetate. The presence of a weak conjugate acid-base pair in the solution imparts the ability to\nneutralize modest amounts of added strong acid or base. For example, strong base added to this solution will\nneutralize hydronium ion, causing the acetic acid ionization equilibrium to shift to the right and generate\nadditional amounts of the weak conjugate base (acetate ion):\n"]], ["block_2", ["Likewise, strong acid added to this buffer solution will shift the above ionization equilibrium left, producing\nadditional amounts of the weak conjugate acid (acetic acid). Figure 14.15 provides a graphical illustration of\nthe changes in conjugate-partner concentration that occur in this buffer solution when strong acid and base\nare added. The buffering action of the solution is essentially a result of the added strong acid and base being\nconverted to the weak acid and base that make up the buffer's conjugate pair. The weaker acid and base\nundergo only slight ionization, as compared with the complete ionization of the strong acid and base, and the\nsolution pH, therefore, changes much less drastically than it would in an unbuffered solution.\n"]], ["block_3", [{"image_0": "738_0.png", "coords": [72, 259, 540, 455]}]], ["block_4", [" pH Changes in Buffered and Unbuffered Solutions \n"]], ["block_5", ["Acetate buffers are used in biochemical studies of enzymes and other chemical components of cells to prevent\npH changes that might affect the biochemical activity of these compounds.\n"]], ["block_6", ["(a) Calculate the pH of an acetate buffer that is a mixture with 0.10 M acetic acid and 0.10 M sodium acetate.\n"]], ["block_7", ["(b) Calculate the pH after 1.0 mL of 0.10 NaOH is added to 100 mL of this buffer.\n"]], ["block_8", ["(c) For comparison, calculate the pH after 1.0 mL of 0.10 M NaOH is added to 100 mL of a solution of an\nunbuffered solution with a pH of 4.74.\n"]], ["block_9", [" Solution \n"]], ["block_10", ["(a) Following the ICE approach to this equilibrium calculation yields the following:\n"]], ["block_11", ["EXAMPLE 14.20\n"]], ["block_12", [" FIGURE 14.15 \nBuffering action in a mixture of acetic acid and acetate salt.\n"]], ["block_13", [" 14.6 \u2022 Buffers \n 725 \n"]]], "page_739": [["block_0", [" 726 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", [{"image_0": "739_0.png", "coords": [72, 57, 503, 153]}]], ["block_2", ["Substituting the equilibrium concentration terms into the Ka expression, assuming x << 0.10, and solving the\nsimplified equation for x yields\n"]], ["block_3", ["(b) Calculate the pH after 1.0 mL of 0.10 M NaOH is added to 100 mL of this buffer.\n"]], ["block_4", ["Adding strong base will neutralize some of the acetic acid, yielding the conjugate base acetate ion. Compute\nthe new concentrations of these two buffer components, then repeat the equilibrium calculation of part (a)\nusing these new concentrations.\n"]], ["block_5", ["The initial molar amount of acetic acid is\n"]], ["block_6", ["The amount of acetic acid remaining after some is neutralized by the added base is\n"]], ["block_7", ["The newly formed acetate ion, along with the initially present acetate, gives a final acetate concentration of\n"]], ["block_8", ["Compute molar concentrations for the two buffer components:\n"]], ["block_9", ["Using these concentrations, the pH of the solution may be computed as in part (a) above, yielding pH = 4.75\n(only slightly different from that prior to adding the strong base).\n"]], ["block_10", ["(c) For comparison, calculate the pH after 1.0 mL of 0.10 M NaOH is added to 100 mL of a solution of an\nunbuffered solution with a pH of 4.74.\n"]], ["block_11", ["The amount of hydronium ion initially present in the solution is\n"]], ["block_12", ["The amount of hydroxide ion added to the solution is\n"]], ["block_13", [" Access for free at openstax.org \n"]]], "page_740": [["block_0", ["The added hydroxide will neutralize hydronium ion via the reaction\n"]], ["block_1", ["The 1:1 stoichiometry of this reaction shows that an excess of hydroxide has been added (greater molar\namount than the initially present hydronium ion).\n"]], ["block_2", ["The amount of hydroxide ion remaining is\n"]], ["block_3", ["corresponding to a hydroxide molarity of\n"]], ["block_4", ["The pH of the solution is then calculated to be\n"]], ["block_5", ["In this unbuffered solution, addition of the base results in a significant rise in pH (from 4.74 to 10.99)\ncompared with the very slight increase observed for the buffer solution in part (b) (from 4.74 to 4.75).\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["Show that adding 1.0 mL of 0.10 M HCl changes the pH of 100 mL of a 1.8\n10M HCl solution from 4.74 to\n"]], ["block_8", ["3.00.\n"]], ["block_9", [" Answer: \nInitial pH of 1.8\n10M HCl; pH = \u2212log[H3O] = \u2212log[1.8\n10] = 4.74\n"]], ["block_10", ["Moles of H3Oin 100 mL 1.8\n10M HCl; 1.8\n10moles/L\n0.100 L = 1.8\n10\n"]], ["block_11", ["Moles of H3Oadded by addition of 1.0 mL of 0.10 M HCl: 0.10 moles/L\n0.0010 L = 1.0\n10moles; final pH\n"]], ["block_12", ["after addition of 1.0 mL of 0.10 M HCl:\n"]], ["block_13", [" Buffer Capacity \n"]], ["block_14", ["Buffer solutions do not have an unlimited capacity to keep the pH relatively constant (Figure 14.16). Instead,\nthe ability of a buffer solution to resist changes in pH relies on the presence of appreciable amounts of its\nconjugate weak acid-base pair. When enough strong acid or base is added to substantially lower the\nconcentration of either member of the buffer pair, the buffering action within the solution is compromised.\n"]], ["block_15", [{"image_0": "740_0.png", "coords": [72, 518, 540, 649]}]], ["block_16", [" FIGURE 14.16 \nThe indicator color (methyl orange) shows that a small amount of acid added to a buffered solution\n"]], ["block_17", ["of pH 8 (beaker on the left) has little affect on the buffered system (middle beaker). However, a large amount of acid\nexhausts the buffering capacity of the solution and the pH changes dramatically (beaker on the right). (credit:\nmodification of work by Mark Ott)\n"]], ["block_18", ["The buffer capacity is the amount of acid or base that can be added to a given volume of a buffer solution\nbefore the pH changes significantly, usually by one unit. Buffer capacity depends on the amounts of the weak\n"]], ["block_19", [" 14.6 \u2022 Buffers \n 727 \n"]]], "page_741": [["block_0", [" 728 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", ["acid and its conjugate base that are in a buffer mixture. For example, 1 L of a solution that is 1.0 M in acetic\nacid and 1.0 M in sodium acetate has a greater buffer capacity than 1 L of a solution that is 0.10 M in acetic acid\nand 0.10 M in sodium acetate even though both solutions have the same pH. The first solution has more buffer\ncapacity because it contains more acetic acid and acetate ion.\n"]], ["block_2", [" Selection of Suitable Buffer Mixtures \n"]], ["block_3", ["There are two useful rules of thumb for selecting buffer mixtures:\n"]], ["block_4", ["Blood is an important example of a buffered solution, with the principal acid and ion responsible for the\nbuffering action being carbonic acid, H2CO3, and the bicarbonate ion,\nWhen a hydronium ion is\n"]], ["block_5", ["introduced to the blood stream, it is removed primarily by the reaction:\n"]], ["block_6", ["An added hydroxide ion is removed by the reaction:\n"]], ["block_7", ["The added strong acid or base is thus effectively converted to the much weaker acid or base of the buffer pair\n(H3Ois converted to H2CO3 and OHis converted to HCO3). The pH of human blood thus remains very near\nthe value determined by the buffer pairs pKa, in this case, 7.35. Normal variations in blood pH are usually less\nthan 0.1, and pH changes of 0.4 or greater are likely to be fatal.\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["1.\nA good buffer mixture should have about equal concentrations of both of its components. A buffer solution\nhas generally lost its usefulness when one component of the buffer pair is less than about 10% of the other.\nFigure 14.17 shows how pH changes for an acetic acid-acetate ion buffer as base is added. The initial pH is\n4.74. A change of 1 pH unit occurs when the acetic acid concentration is reduced to 11% of the acetate ion\nconcentration.\n"]], ["block_10", ["2.\nWeak acids and their salts are better as buffers for pHs less than 7; weak bases and their salts are better as\nbuffers for pHs greater than 7.\n"]], ["block_11", [" FIGURE 14.17 \nChange in pH as an increasing amount of a 0.10-M NaOH solution is added to 100 mL of a\n"]], ["block_12", ["buffer solution in which, initially, [CH3CO2H] = 0.10 M and\nNote the greatly diminished\n"]], ["block_13", ["buffering action occurring after the buffer capacity has been reached, resulting in drastic rises in pH on adding\nmore strong base.\n"]], ["block_14", [{"image_0": "741_0.png", "coords": [135, 216, 495, 473]}]]], "page_742": [["block_0", [" The Henderson-Hasselbalch Equation \n"]], ["block_1", ["The ionization-constant expression for a solution of a weak acid can be written as:\n"]], ["block_2", ["Rearranging to solve for [H3O] yields:\n"]], ["block_3", ["Taking the negative logarithm of both sides of this equation gives\n"]], ["block_4", ["which can be written as\n"]], ["block_5", ["where pKa is the negative of the logarithm of the ionization constant of the weak acid (pKa = \u2212log Ka). This\nequation relates the pH, the ionization constant of a weak acid, and the concentrations of the weak conjugate\nacid-base pair in a buffered solution. Scientists often use this expression, called the Henderson-Hasselbalch \n equation , to calculate the pH of buffer solutions. It is important to note that the \u201cx is small\u201d assumption must\nbe valid to use this equation.\n"]], ["block_6", [" Medicine: The Buffer System in Blood \nThe normal pH of human blood is about 7.4. The carbonate buffer system in the blood uses the following\nequilibrium reaction:\n"]], ["block_7", ["Portrait of a Chemist\n"]], ["block_8", [" Lawrence Joseph Henderson and Karl Albert Hasselbalch \nLawrence Joseph Henderson (1878\u20131942) was an American physician, biochemist and physiologist, to\nname only a few of his many pursuits. He obtained a medical degree from Harvard and then spent 2 years\nstudying in Strasbourg, then a part of Germany, before returning to take a lecturer position at Harvard. He\neventually became a professor at Harvard and worked there his entire life. He discovered that the acid-base\nbalance in human blood is regulated by a buffer system formed by the dissolved carbon dioxide in blood.\nHe wrote an equation in 1908 to describe the carbonic acid-carbonate buffer system in blood. Henderson\nwas broadly knowledgeable; in addition to his important research on the physiology of blood, he also wrote\non the adaptations of organisms and their fit with their environments, on sociology and on university\neducation. He also founded the Fatigue Laboratory, at the Harvard Business School, which examined\nhuman physiology with specific focus on work in industry, exercise, and nutrition.\n"]], ["block_9", ["In 1916, Karl Albert Hasselbalch (1874\u20131962), a Danish physician and chemist, shared authorship in a\npaper with Christian Bohr in 1904 that described the Bohr effect, which showed that the ability of\nhemoglobin in the blood to bind with oxygen was inversely related to the acidity of the blood and the\nconcentration of carbon dioxide. The pH scale was introduced in 1909 by another Dane, S\u00f8rensen, and in\n1912, Hasselbalch published measurements of the pH of blood. In 1916, Hasselbalch expressed\nHenderson\u2019s equation in logarithmic terms, consistent with the logarithmic scale of pH, and thus the\nHenderson-Hasselbalch equation was born.\n"]], ["block_10", ["HOW SCIENCES INTERCONNECT\n"]], ["block_11", [" 14.6 \u2022 Buffers \n 729 \n"]]], "page_743": [["block_0", [" 730 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", ["The concentration of carbonic acid, H2CO3 is approximately 0.0012 M, and the concentration of the hydrogen\ncarbonate ion,\nis around 0.024 M. Using the Henderson-Hasselbalch equation and the pKa of carbonic\n"]], ["block_2", ["acid at body temperature, we can calculate the pH of blood:\n"]], ["block_3", ["The fact that the H2CO3 concentration is significantly lower than that of the\nion may seem unusual, but\n"]], ["block_4", ["this imbalance is due to the fact that most of the by-products of our metabolism that enter our bloodstream are\nacidic. Therefore, there must be a larger proportion of base than acid, so that the capacity of the buffer will not\nbe exceeded.\n"]], ["block_5", ["Lactic acid is produced in our muscles when we exercise. As the lactic acid enters the bloodstream, it is\nneutralized by the\nion, producing H2CO3. An enzyme then accelerates the breakdown of the excess\n"]], ["block_6", ["carbonic acid to carbon dioxide and water, which can be eliminated by breathing. In fact, in addition to the\nregulating effects of the carbonate buffering system on the pH of blood, the body uses breathing to regulate\nblood pH. If the pH of the blood decreases too far, an increase in breathing removes CO2 from the blood\nthrough the lungs driving the equilibrium reaction such that [H3O] is lowered. If the blood is too alkaline, a\nlower breath rate increases CO2 concentration in the blood, driving the equilibrium reaction the other way,\nincreasing [H] and restoring an appropriate pH.\n"]], ["block_7", ["View information (http://openstax.org/l/16BufferSystem) on the buffer system encountered in natural waters.\n"]], ["block_8", [" 14.7 Acid-Base Titrations \n"]], ["block_9", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_10", ["As seen in the chapter on the stoichiometry of chemical reactions, titrations can be used to quantitatively\nanalyze solutions for their acid or base concentrations. In this section, we will explore the underlying chemical\nequilibria that make acid-base titrimetry a useful analytical technique.\n"]], ["block_11", [" Titration Curves \n"]], ["block_12", ["A titration curve is a plot of some solution property versus the amount of added titrant. For acid-base\ntitrations, solution pH is a useful property to monitor because it varies predictably with the solution\ncomposition and, therefore, may be used to monitor the titration\u2019s progress and detect its end point. The\nfollowing example exercise demonstrates the computation of pH for a titration solution after additions of\nseveral specified titrant volumes. The first example involves a strong acid titration that requires only\nstoichiometric calculations to derive the solution pH. The second example addresses a weak acid titration\nrequiring equilibrium calculations.\n"]], ["block_13", [" Calculating pH for Titration Solutions: Strong Acid/Strong Base \n"]], ["block_14", ["A titration is carried out for 25.00 mL of 0.100 M HCl (strong acid) with 0.100 M of a strong base NaOH (the\ntitration curve is shown in Figure 14.18). Calculate the pH at these volumes of added base solution:\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["\u2022\nInterpret titration curves for strong and weak acid-base systems\n"]], ["block_17", ["\u2022\nCompute sample pH at important stages of a titration\n"]], ["block_18", ["\u2022\nExplain the function of acid-base indicators\n"]], ["block_19", ["LINK TO LEARNING\n"]], ["block_20", ["EXAMPLE 14.21\n"]]], "page_744": [["block_0", ["(c) Titrant volume = 25.00 mL. This titrant addition involves a stoichiometric amount of base (the equivalence\npoint), and so only products of the neutralization reaction are in solution (water and NaCl). Neither the cation\nnor the anion of this salt undergo acid-base ionization; the only process generating hydronium ions is the\nautoprotolysis of water. The solution is neutral, having a pH = 7.00.\n"]], ["block_1", ["(a) 0.00 mL\n"]], ["block_2", ["(b) 12.50 mL\n"]], ["block_3", ["(c) 25.00 mL\n"]], ["block_4", ["(d) 37.50 mL\n"]], ["block_5", [" Solution \n"]], ["block_6", ["(a) Titrant volume = 0 mL. The solution pH is due to the acid ionization of HCl. Because this is a strong acid, the\nionization is complete and the hydronium ion molarity is 0.100 M. The pH of the solution is then\n"]], ["block_7", ["(b) Titrant volume = 12.50 mL. Since the acid sample and the base titrant are both monoprotic and equally\nconcentrated, this titrant addition involves less than a stoichiometric amount of base, and so it is completely\nconsumed by reaction with the excess acid in the sample. The concentration of acid remaining is computed by\nsubtracting the consumed amount from the intial amount and then dividing by the solution volume:\n"]], ["block_8", ["(d) Titrant volume = 37.50 mL. This involves the addition of titrant in excess of the equivalence point. The\nsolution pH is then calculated using the concentration of hydroxide ion:\n"]], ["block_9", ["pH = 14 \u2212 pOH = 14 + log([OH]) = 14 + log(0.0200) = 12.30\n"]], ["block_10", [" Check Your Learning \n"]], ["block_11", ["Calculate the pH for the strong acid/strong base titration between 50.0 mL of 0.100 M HNO3(aq) and 0.200 M\nNaOH (titrant) at the listed volumes of added base: 0.00 mL, 15.0 mL, 25.0 mL, and 40.0 mL.\n"]], ["block_12", [" Answer: \n0.00: 1.000; 15.0: 1.5111; 25.0: 7; 40.0: 12.523\n"]], ["block_13", [" Titration of a Weak Acid with a Strong Base \n"]], ["block_14", ["Consider the titration of 25.00 mL of 0.100 M CH3CO2H with 0.100 M NaOH. The reaction can be represented\nas:\n"]], ["block_15", ["Calculate the pH of the titration solution after the addition of the following volumes of NaOH titrant:\n"]], ["block_16", ["(a) 0.00 mL\n"]], ["block_17", ["(b) 25.00 mL\n"]], ["block_18", ["(c) 12.50 mL\n"]], ["block_19", ["EXAMPLE 14.22\n"]], ["block_20", [" 14.7 \u2022 Acid-Base Titrations \n 731 \n"]]], "page_745": [["block_0", [" 732 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", ["(d) 37.50 mL\n"]], ["block_2", [" Solution \n"]], ["block_3", ["(a) The initial pH is computed for the acetic acid solution in the usual ICE approach:\n"]], ["block_4", ["(b) The acid and titrant are both monoprotic and the sample and titrant solutions are equally concentrated;\nthus, this volume of titrant represents the equivalence point. Unlike the strong-acid example above, however,\nthe reaction mixture in this case contains a weak conjugate base (acetate ion). The solution pH is computed\nconsidering the base ionization of acetate, which is present at a concentration of\n"]], ["block_5", ["Base ionization of acetate is represented by the equation\n"]], ["block_6", ["Assuming x << 0.0500, the pH may be calculated via the usual ICE approach:\n"]], ["block_7", ["Note that the pH at the equivalence point of this titration is significantly greater than 7, as expected when\ntitrating a weak acid with a strong base.\n"]], ["block_8", ["(c) Titrant volume = 12.50 mL. This volume represents one-half of the stoichiometric amount of titrant, and so\none-half of the acetic acid has been neutralized to yield an equivalent amount of acetate ion. The\nconcentrations of these conjugate acid-base partners, therefore, are equal. A convenient approach to\ncomputing the pH is use of the Henderson-Hasselbalch equation:\n"]], ["block_9", ["(pH = pKa at the half-equivalence point in a titration of a weak acid)\n"]], ["block_10", ["(d) Titrant volume = 37.50 mL. This volume represents a stoichiometric excess of titrant, and a reaction\nsolution containing both the titration product, acetate ion, and the excess strong titrant. In such solutions, the\nsolution pH is determined primarily by the amount of excess strong base:\n"]], ["block_11", [" Check Your Learning \n"]], ["block_12", ["Calculate the pH for the weak acid/strong base titration between 50.0 mL of 0.100 M HCOOH(aq) (formic acid)\nand 0.200 M NaOH (titrant) at the listed volumes of added base: 0.00 mL, 15.0 mL, 25.0 mL, and 30.0 mL.\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", ["and\n"]]], "page_746": [["block_0", [" Answer: \n0.00 mL: 2.37; 15.0 mL: 3.92; 25.00 mL: 8.29; 30.0 mL: 12.097\n"]], ["block_1", ["Performing additional calculations similar to those in the preceding example permits a more full assessment\nof titration curves. A summary of pH/volume data pairs for the strong and weak acid titrations is provided in\nTable 14.2 and plotted as titration curves in Figure 14.18. A comparison of these two curves illustrates several\nimportant concepts that are best addressed by identifying the four stages of a titration:\n"]], ["block_2", ["initial state (added titrant volume = 0 mL): pH is determined by the acid being titrated; because the two acid\nsamples are equally concentrated, the weak acid will exhibit a greater initial pH\n"]], ["block_3", ["pre-equivalence point (0 mL < V < 25 mL): solution pH increases gradually and the acid is consumed by\nreaction with added titrant; composition includes unreacted acid and the reaction product, its conjugate base\n"]], ["block_4", ["equivalence point (V = 25 mL): a drastic rise in pH is observed as the solution composition transitions from\nacidic to either neutral (for the strong acid sample) or basic (for the weak acid sample), with pH determined by\nionization of the conjugate base of the acid\n"]], ["block_5", ["postequivalence point (V > 25 mL): pH is determined by the amount of excess strong base titrant added; since\nboth samples are titrated with the same titrant, both titration curves appear similar at this stage.\n"]], ["block_6", ["1 Titration of 25.00 mL of 0.100 M HCl (0.00250 mol of HCI) with 0.100 M NaOH.\n2 Titration of 25.00 mL of 0.100 M CH3CO2H (0.00250 mol of CH3CO2H) with 0.100 M NaOH.\n"]], ["block_7", [" Volume of 0.100 M NaOH \n Added (mL) \n"]], ["block_8", ["0.0\n0.0\n1.00\n2.87\n"]], ["block_9", ["5.0\n0.00050\n1.18\n4.14\n"]], ["block_10", ["10.0\n0.00100\n1.37\n4.57\n"]], ["block_11", ["15.0\n0.00150\n1.60\n4.92\n"]], ["block_12", ["20.0\n0.00200\n1.95\n5.35\n"]], ["block_13", ["22.0\n0.00220\n2.20\n5.61\n"]], ["block_14", ["24.0\n0.00240\n2.69\n6.13\n"]], ["block_15", ["24.5\n0.00245\n3.00\n6.44\n"]], ["block_16", ["24.9\n0.00249\n3.70\n7.14\n"]], ["block_17", ["25.0\n0.00250\n7.00\n8.72\n"]], ["block_18", ["25.1\n0.00251\n10.30\n10.30\n"]], ["block_19", ["25.5\n0.00255\n11.00\n11.00\n"]], ["block_20", ["26.0\n0.00260\n11.29\n11.29\n"]], ["block_21", ["pH Values in the Titrations of a Strong Acid and of a Weak Acid\n"]], ["block_22", [" Moles of NaOH \n Added \n"]], ["block_23", [" pH Values 0.100 M \n HCl 1 \n"]], ["block_24", [" pH Values 0.100 M \n CH 3 CO 2 H 2 \n"]], ["block_25", [" 14.7 \u2022 Acid-Base Titrations \n 733 \n"]]], "page_747": [["block_0", [" 734 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", [" TABLE 14.2 \n"]], ["block_2", [{"image_0": "747_0.png", "coords": [72, 282, 540, 545]}]], ["block_3", [" FIGURE 14.18 \n(a) The titration curve for the titration of 25.00 mL of 0.100 M HCl (strong acid) with 0.100 M NaOH\n"]], ["block_4", ["(strong base) has an equivalence point of 7.00 pH. (b) The titration curve for the titration of 25.00 mL of 0.100 M\nacetic acid (weak acid) with 0.100 M NaOH (strong base) has an equivalence point of 8.72 pH.\n"]], ["block_5", [" Acid-Base Indicators \n"]], ["block_6", ["Certain organic substances change color in dilute solution when the hydronium ion concentration reaches a\nparticular value. For example, phenolphthalein is a colorless substance in any aqueous solution with a\nhydronium ion concentration greater than 5.0\n10M (pH < 8.3). In more basic solutions where the\n"]], ["block_7", ["hydronium ion concentration is less than 5.0\n10M (pH > 8.3), it is red or pink. Substances such as\n"]], ["block_8", ["phenolphthalein, which can be used to determine the pH of a solution, are called acid-base indicators . Acid-\nbase indicators are either weak organic acids or weak organic bases.\n"]], ["block_9", ["The equilibrium in a solution of the acid-base indicator methyl orange, a weak acid, can be represented by an\nequation in which we use HIn as a simple representation for the complex methyl orange molecule:\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [" Volume of 0.100 M NaOH \n Added (mL) \n"]], ["block_12", ["28.0\n0.00280\n11.75\n11.75\n"]], ["block_13", ["30.0\n0.00300\n11.96\n11.96\n"]], ["block_14", ["35.0\n0.00350\n12.22\n12.22\n"]], ["block_15", ["40.0\n0.00400\n12.36\n12.36\n"]], ["block_16", ["45.0\n0.00450\n12.46\n12.46\n"]], ["block_17", ["50.0\n0.00500\n12.52\n12.52\n"]], ["block_18", [" Moles of NaOH \n Added \n"]], ["block_19", [" pH Values 0.100 M \n HCl 1 \n"]], ["block_20", [" pH Values 0.100 M \n CH 3 CO 2 H 2 \n"]]], "page_748": [["block_0", ["The anion of methyl orange, In, is yellow, and the nonionized form, HIn, is red. When we add acid to a solution\nof methyl orange, the increased hydronium ion concentration shifts the equilibrium toward the nonionized red\nform, in accordance with Le Ch\u00e2telier\u2019s principle. If we add base, we shift the equilibrium towards the yellow\nform. This behavior is completely analogous to the action of buffers.\n"]], ["block_1", ["The perceived color of an indicator solution is determined by the ratio of the concentrations of the two species\nInand HIn. If most of the indicator (typically about 60\u221290% or more) is present as In, the perceived color of\nthe solution is yellow. If most is present as HIn, then the solution color appears red. The Henderson-\nHasselbalch equation is useful for understanding the relationship between the pH of an indicator solution and\nits composition (thus, perceived color):\n"]], ["block_2", ["In solutions where pH > pKa, the logarithmic term must be positive, indicating an excess of the conjugate base\nform of the indicator (yellow solution). When pH < pKa, the log term must be negative, indicating an excess of\nthe conjugate acid (red solution). When the solution pH is close to the indicator pKa, appreciable amounts of\nboth conjugate partners are present, and the solution color is that of an additive combination of each (yellow\nand red, yielding orange). The color change interval (or pH interval) for an acid-base indicator is defined as\nthe range of pH values over which a change in color is observed, and for most indicators this range is\napproximately pKa \u00b1 1.\n"]], ["block_3", ["There are many different acid-base indicators that cover a wide range of pH values and can be used to\ndetermine the approximate pH of an unknown solution by a process of elimination. Universal indicators and\npH paper contain a mixture of indicators and exhibit different colors at different pHs. Figure 14.19 presents\nseveral indicators, their colors, and their color-change intervals.\n"]], ["block_4", [" 14.7 \u2022 Acid-Base Titrations \n 735 \n"]]], "page_749": [["block_0", [" 736 \n 14 \u2022 Acid-Base Equilibria \n"]], ["block_1", [{"image_0": "749_0.png", "coords": [72, 57, 540, 466]}]], ["block_2", [" Access for free at openstax.org \n"]], ["block_3", [" FIGURE 14.19 \nThis chart illustrates the color change intervals for several acid-base indicators.\n"]]], "page_750": [["block_0", [{"image_0": "750_0.png", "coords": [72, 57, 540, 371]}]], ["block_1", [" FIGURE 14.20 \nTitration curves for strong and weak acids illustrating the proper choice of acid-base indicator. Any\n"]], ["block_2", ["of the three indicators will exhibit a reasonably sharp color change at the equivalence point of the strong acid\ntitration, but only phenolphthalein is suitable for use in the weak acid titration.\n"]], ["block_3", ["The titration curves shown in Figure 14.20 illustrate the choice of a suitable indicator for specific titrations. In\nthe strong acid titration, use of any of the three indicators should yield reasonably sharp color changes and\naccurate end point determinations. For this titration, the solution pH reaches the lower limit of the methyl\norange color change interval after addition of ~24 mL of titrant, at which point the initially red solution would\nbegin to appear orange. When 25 mL of titrant has been added (the equivalence point), the pH is well above the\nupper limit and the solution will appear yellow. The titration's end point may then be estimated as the volume\nof titrant that yields a distinct orange-to-yellow color change. This color change would be challenging for most\nhuman eyes to precisely discern. More-accurate estimates of the titration end point are possible using either\nlitmus or phenolphthalein, both of which exhibit color change intervals that are encompassed by the steep rise\nin pH that occurs around the 25.00 mL equivalence point.\n"]], ["block_4", ["The weak acid titration curve in Figure 14.20 shows that only one of the three indicators is suitable for end\npoint detection. If methyl orange is used in this titration, the solution will undergo a gradual red-to-orange-to-\nyellow color change over a relatively large volume interval (0\u20136 mL), completing the color change well before\nthe equivalence point (25 mL) has been reached. Use of litmus would show a color change that begins after\nadding 7\u20138 mL of titrant and ends just before the equivalence point. Phenolphthalein, on the other hand,\nexhibits a color change interval that nicely brackets the abrupt change in pH occurring at the titration's\nequivalence point. A sharp color change from colorless to pink will be observed within a very small volume\ninterval around the equivalence point.\n"]], ["block_5", [" 14.7 \u2022 Acid-Base Titrations \n 737 \n"]]], "page_751": [["block_0", [" 738 \n 14 \u2022 Key Terms \n"]], ["block_1", [" Key Terms \n"]], ["block_2", [" acid ionization \nreaction involving the transfer of a\n"]], ["block_3", [" acid ionization constant (K a ) \nequilibrium constant\n"]], ["block_4", [" acid-base indicator \nweak acid or base whose\n"]], ["block_5", [" acidic \na solution in which [H3O] > [OH]\n"]], ["block_6", [" amphiprotic \nspecies that may either donate or\n"]], ["block_7", [" amphoteric \nspecies that can act as either an acid\n"]], ["block_8", [" autoionization \nreaction between identical species\n"]], ["block_9", [" base ionization \nreaction involving the transfer of a\n"]], ["block_10", [" base ionization constant (K b ) \nequilibrium\n"]], ["block_11", [" basic \na solution in which [H3O] < [OH]\n"]], ["block_12", [" Br\u00f8nsted-Lowry acid \nproton donor\n"]], ["block_13", [" Br\u00f8nsted-Lowry base \nproton acceptor\n"]], ["block_14", [" buffer \nmixture of appreciable amounts of a weak\n"]], ["block_15", [" buffer capacity \namount of an acid or base that can\n"]], ["block_16", [" color-change interval \nrange in pH over which the\n"]], ["block_17", [" conjugate acid \nsubstance formed when a base\n"]], ["block_18", [" conjugate base \nsubstance formed when an acid\n"]], ["block_19", [" Key Equations \n"]], ["block_20", [" Access for free at openstax.org \n"]], ["block_21", ["Kw = [H3O][OH] = 1.0\n10(at 25 \u00b0C)\n"]], ["block_22", ["pOH = \u2212log[OH]\n"]], ["block_23", ["[H3O] = 10\n"]], ["block_24", ["[OH] = 10\n"]], ["block_25", ["pH + pOH = pKw = 14.00 at 25 \u00b0C\n"]], ["block_26", ["proton from an acid to water, yielding hydronium\nions and the conjugate base of the acid\n"]], ["block_27", ["for an acid ionization reaction\n"]], ["block_28", ["conjugate partner imparts a different solution\ncolor; used in visual assessments of solution pH\n"]], ["block_29", ["accept a proton in a Bronsted-Lowry acid-base\nreaction\n"]], ["block_30", ["or a base\n"]], ["block_31", ["yielding ionic products; for water, this reaction\ninvolves transfer of protons to yield hydronium\nand hydroxide ions\n"]], ["block_32", ["proton from water to a base, yielding hydroxide\nions and the conjugate acid of the base\n"]], ["block_33", ["constant for a base ionization reaction\n"]], ["block_34", ["acid-base pair the pH of a buffer resists change\nwhen small amounts of acid or base are added\n"]], ["block_35", ["be added to a volume of a buffer solution before\nits pH changes significantly (usually by one pH\nunit)\n"]], ["block_36", ["color change of an indicator is observed\n"]], ["block_37", ["gains a proton\n"]], ["block_38", [" diprotic acid \nacid containing two ionizable\n"]], ["block_39", [" diprotic base \nbase capable of accepting two\n"]], ["block_40", [" Henderson-Hasselbalch equation \nlogarithmic\n"]], ["block_41", [" ion-product constant for water (K w ) \nequilibrium\n"]], ["block_42", [" leveling effect \nobservation that acid-base strength\n"]], ["block_43", [" monoprotic acid \nacid containing one ionizable\n"]], ["block_44", [" neutral \ndescribes a solution in which [H3O] =\n"]], ["block_45", [" oxyacid \nternary compound with acidic properties,\n"]], ["block_46", [" percent ionization \nratio of the concentration of\n"]], ["block_47", [" pH \nlogarithmic measure of the concentration of\n"]], ["block_48", [" pOH \nlogarithmic measure of the concentration of\n"]], ["block_49", [" stepwise ionization \nprocess in which a polyprotic\n"]], ["block_50", [" titration curve \nplot of some sample property (such\n"]], ["block_51", [" triprotic acid \nacid that contains three ionizable\n"]], ["block_52", ["loses a proton\n"]], ["block_53", ["hydrogen atoms per molecule\n"]], ["block_54", ["protons\n"]], ["block_55", ["version of the acid ionization constant\nexpression, conveniently formatted for\ncalculating the pH of buffer solutions\n"]], ["block_56", ["constant for the autoionization of water\n"]], ["block_57", ["of solutes in a given solvent is limited to that of\nthe solvent\u2019s characteristic acid and base species\n(in water, hydronium and hydroxide ions,\nrespectively)\n"]], ["block_58", ["hydrogen atom per molecule\n"]], ["block_59", ["[OH]\n"]], ["block_60", ["molecules of which contain a central nonmetallic\natom bonded to one or more O atoms, at least one\nof which is bonded to an ionizable H atom\n"]], ["block_61", ["ionized acid to initial acid concentration\nexpressed as a percentage\n"]], ["block_62", ["hydronium ions in a solution\n"]], ["block_63", ["hydroxide ions in a solution\n"]], ["block_64", ["acid is ionized by losing protons sequentially\n"]], ["block_65", ["as pH) versus volume of added titrant\n"]], ["block_66", ["hydrogen atoms per molecule\n"]]], "page_752": [["block_0", [" Summary \n"]], ["block_1", [" 14.1 Br\u00f8nsted-Lowry Acids and Bases \n"]], ["block_2", ["A compound that can donate a proton (a hydrogen\nion) to another compound is called a Br\u00f8nsted-\nLowry acid. The compound that accepts the proton\nis called a Br\u00f8nsted-Lowry base. The species\nremaining after a Br\u00f8nsted-Lowry acid has lost a\nproton is the conjugate base of the acid. The species\nformed when a Br\u00f8nsted-Lowry base gains a proton\nis the conjugate acid of the base. Thus, an acid-base\nreaction occurs when a proton is transferred from\nan acid to a base, with formation of the conjugate\nbase of the reactant acid and formation of the\nconjugate acid of the reactant base. Amphiprotic\nspecies can act as both proton donors and proton\nacceptors. Water is the most important amphiprotic\nspecies. It can form both the hydronium ion, H3O,\nand the hydroxide ion, OHwhen it undergoes\nautoionization:\n"]], ["block_3", ["The ion product of water, Kw is the equilibrium\nconstant for the autoionization reaction:\n"]], ["block_4", [" 14.2 pH and pOH \n"]], ["block_5", ["Concentrations of hydronium and hydroxide ions in\naqueous media are often represented as logarithmic\npH and pOH values, respectively. At 25 \u00b0C, the\nautoprotolysis equilibrium for water requires the\nsum of pH and pOH to equal 14 for any aqueous\nsolution. The relative concentrations of hydronium\nand hydroxide ion in a solution define its status as\nacidic ([H3O] > [OH]), basic ([H3O] < [OH]), or\nneutral ([H3O] = [OH]). At 25 \u00b0C, a pH < 7 indicates\nan acidic solution, a pH > 7 a basic solution, and a\npH = 7 a neutral solution.\n"]], ["block_6", [" 14.3 Relative Strengths of Acids and Bases \n"]], ["block_7", ["The relative strengths of acids and bases are\nreflected in the magnitudes of their ionization\nconstants; the stronger the acid or base, the larger\nits ionization constant. A reciprocal relation exists\n"]], ["block_8", ["Ka\nKb = 1.0\n10= Kw\n"]], ["block_9", ["pKa = \u2212log Ka\npKb = \u2212log Kb\n"]], ["block_10", ["between the strengths of a conjugate acid-base pair:\nthe stronger the acid, the weaker its conjugate base.\nWater exerts a leveling effect on dissolved acids or\nbases, reacting completely to generate its\ncharacteristic hydronium and hydroxide ions (the\nstrongest acid and base that may exist in water). The\nstrengths of the binary acids increase from left to\nright across a period of the periodic table (CH4 < NH3\n< H2O < HF), and they increase down a group (HF <\nHCl < HBr < HI). The strengths of oxyacids that\ncontain the same central element increase as the\noxidation number of the element increases (H2SO3 <\nH2SO4). The strengths of oxyacids also increase as\nthe electronegativity of the central element\nincreases [H2SeO4 < H2SO4].\n"]], ["block_11", [" 14.4 Hydrolysis of Salts \n"]], ["block_12", ["The ions composing salts may possess acidic or\nbasic character, ionizing when dissolved in water to\nyield acidic or basic solutions. Acidic cations are\ntypically the conjugate partners of weak bases, and\nbasic anions are the conjugate partners of weak\nacids. Many metal ions bond to water molecules\nwhen dissolved to yield complex ions that may\nfunction as acids.\n"]], ["block_13", [" 14.5 Polyprotic Acids \n"]], ["block_14", ["An acid that contains more than one ionizable\nproton is a polyprotic acid. These acids undergo\nstepwise ionization reactions involving the transfer\nof single protons. The ionization constants for\npolyprotic acids decrease with each subsequent\nstep; these decreases typically are large enough to\npermit simple equilibrium calculations that treat\neach step separately.\n"]], ["block_15", [" 14.6 Buffers \n"]], ["block_16", ["Solutions that contain appreciable amounts of a\nweak conjugate acid-base pair are called buffers. A\nbuffered solution will experience only slight changes\nin pH when small amounts of acid or base are added.\nAddition of large amounts of acid or base can exceed\nthe buffer capacity, consuming most of one\n"]], ["block_17", [" 14 \u2022 Summary \n 739 \n"]]], "page_753": [["block_0", [" 740 \n 14 \u2022 Exercises \n"]], ["block_1", ["conjugate partner and preventing further buffering\naction.\n"]], ["block_2", [" 14.7 Acid-Base Titrations \n"]], ["block_3", ["The titration curve for an acid-base titration is\n"]], ["block_4", [" Exercises \n"]], ["block_5", [" 14.1 Br\u00f8nsted-Lowry Acids and Bases \n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [" 1 . Write equations that show NH3 as both a conjugate acid and a conjugate base.\n 2 . Write equations that show\nacting both as an acid and as a base.\n"]], ["block_8", [" 3 . Show by suitable net ionic equations that each of the following species can act as a Br\u00f8nsted-Lowry acid:\n"]], ["block_9", [" 4 . Show by suitable net ionic equations that each of the following species can act as a Br\u00f8nsted-Lowry acid:\n"]], ["block_10", [" 5 . Show by suitable net ionic equations that each of the following species can act as a Br\u00f8nsted-Lowry base:\n"]], ["block_11", [" 6 . Show by suitable net ionic equations that each of the following species can act as a Br\u00f8nsted-Lowry base:\n"]], ["block_12", [" 7 . What is the conjugate acid of each of the following? What is the conjugate base of each?\n"]], ["block_13", ["(a)\n(b) HCl\n(c) NH3\n(d) CH3CO2H\n(e)\n(f)\n"]], ["block_14", ["(a) HNO3\n(b)\n(c) H2S\n(d) CH3CH2COOH\n(e)\n(f) HS\n"]], ["block_15", ["(a) H2O\n(b) OH\n"]], ["block_16", ["(c) NH3\n(d) CN\n"]], ["block_17", ["(e) S\n"]], ["block_18", ["(f)\n"]], ["block_19", ["(a) HS\n"]], ["block_20", ["(b)\n(c)\n(d) C2H5OH\n(e) O\n"]], ["block_21", ["(f)\n"]], ["block_22", ["(a) OH\n"]], ["block_23", ["(b) H2O\n(c)\n(d) NH3\n(e)\n(f) H2O2\n(g) HS\n"]], ["block_24", ["(h)\n"]], ["block_25", ["typically a plot of pH versus volume of added titrant.\nThese curves are useful in selecting appropriate\nacid-base indicators that will permit accurate\ndeterminations of titration end points.\n"]]], "page_754": [["block_0", [" 10 . Identify and label the Br\u00f8nsted-Lowry acid, its conjugate base, the Br\u00f8nsted-Lowry base, and its conjugate\n"]], ["block_1", [" 11 . What are amphiprotic species? Illustrate with suitable equations.\n 12 . State which of the following species are amphiprotic and write chemical equations illustrating the\n"]], ["block_2", [" 13 . State which of the following species are amphiprotic and write chemical equations illustrating the\n"]], ["block_3", [" 14 . Is the self-ionization of water endothermic or exothermic? The ionization constant for water (Kw) is 2.9\n"]], ["block_4", [" 14.2 pH and pOH \n"]], ["block_5", [" 15 . Explain why a sample of pure water at 40 \u00b0C is neutral even though [H3O] = 1.7\n10M. Kw is 2.9\n10\n"]], ["block_6", [" 16 . The ionization constant for water (Kw) is 2.9\n10at 40 \u00b0C. Calculate [H3O], [OH], pH, and pOH for pure\n"]], ["block_7", [" 17 . The ionization constant for water (Kw) is 9.311\n10at 60 \u00b0C. Calculate [H3O], [OH], pH, and pOH for\n"]], ["block_8", [" 8 . What is the conjugate acid of each of the following? What is the conjugate base of each?\n"]], ["block_9", [" 9 . Identify and label the Br\u00f8nsted-Lowry acid, its conjugate base, the Br\u00f8nsted-Lowry base, and its conjugate\n"]], ["block_10", ["(a) H2S\n(b)\n(c) PH3\n(d) HS\n"]], ["block_11", ["(e)\n(f)\n(g) H4N2\n(h) CH3OH\n"]], ["block_12", ["acid in each of the following equations:\n(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n(g)\n"]], ["block_13", ["acid in each of the following equations:\n(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n(g)\n"]], ["block_14", ["amphiprotic character of these species:\n(a) H2O\n(b)\n(c) S\n"]], ["block_15", ["(d)\n(e)\n"]], ["block_16", ["amphiprotic character of these species.\n(a) NH3\n(b)\n(c) Br\n"]], ["block_17", ["(d)\n(e)\n"]], ["block_18", ["10at 40 \u00b0C and 9.3\n10at 60 \u00b0C.\n"]], ["block_19", ["at 40 \u00b0C.\n"]], ["block_20", ["water at 40 \u00b0C.\n"]], ["block_21", ["pure water at 60 \u00b0C.\n"]], ["block_22", [" 14 \u2022 Exercises \n 741 \n"]]], "page_755": [["block_0", [" 742 \n 14 \u2022 Exercises \n"]], ["block_1", [" 18 . Calculate the pH and the pOH of each of the following solutions at 25 \u00b0C for which the substances ionize\n"]], ["block_2", [" 19 . Calculate the pH and the pOH of each of the following solutions at 25 \u00b0C for which the substances ionize\n"]], ["block_3", [" 20 . What are the pH and pOH of a solution of 2.0 M HCl, which ionizes completely?\n 21 . What are the hydronium and hydroxide ion concentrations in a solution whose pH is 6.52?\n 22 . Calculate the hydrogen ion concentration and the hydroxide ion concentration in wine from its pH. See\n"]], ["block_4", [" 23 . Calculate the hydronium ion concentration and the hydroxide ion concentration in lime juice from its pH.\n"]], ["block_5", [" 24 . The hydronium ion concentration in a sample of rainwater is found to be 1.7\n10M at 25 \u00b0C. What is the\n"]], ["block_6", [" 25 . The hydroxide ion concentration in household ammonia is 3.2\n10M at 25 \u00b0C. What is the\n"]], ["block_7", [" 14.3 Relative Strengths of Acids and Bases \n"]], ["block_8", [" 26 . Explain why the neutralization reaction of a strong acid and a weak base gives a weakly acidic solution.\n 27 . Explain why the neutralization reaction of a weak acid and a strong base gives a weakly basic solution.\n 28 . Use this list of important industrial compounds (and Figure 14.8) to answer the following questions\n"]], ["block_9", [" 29 . The odor of vinegar is due to the presence of acetic acid, CH3CO2H, a weak acid. List, in order of\n"]], ["block_10", [" 30 . Household ammonia is a solution of the weak base NH3 in water. List, in order of descending\n"]], ["block_11", [" 31 . Explain why the ionization constant, Ka, for H2SO4 is larger than the ionization constant for H2SO3.\n 32 . Explain why the ionization constant, Ka, for HI is larger than the ionization constant for HF.\n 33 . Gastric juice, the digestive fluid produced in the stomach, contains hydrochloric acid, HCl. Milk of\n"]], ["block_12", [" 34 . Nitric acid reacts with insoluble copper(II) oxide to form soluble copper(II) nitrate, Cu(NO3)2, a compound\n"]], ["block_13", [" 35 . What is the ionization constant at 25 \u00b0C for the weak acid\nthe conjugate acid of the weak base\n"]], ["block_14", [" 36 . What is the ionization constant at 25 \u00b0C for the weak acid\nthe conjugate acid of the weak\n"]], ["block_15", [" 37 . Which base, CH3NH2 or (CH3)2NH, is the stronger base? Which conjugate acid,\nor\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["completely:\n(a) 0.200 M HCl\n(b) 0.0143 M NaOH\n(c) 3.0 M HNO3\n(d) 0.0031 M Ca(OH)2\n"]], ["block_18", ["completely:\n(a) 0.000259 M HClO4\n(b) 0.21 M NaOH\n(c) 0.000071 M Ba(OH)2\n(d) 2.5 M KOH\n"]], ["block_19", ["Figure 14.2 for useful information.\n"]], ["block_20", ["See Figure 14.2 for useful information.\n"]], ["block_21", ["concentration of hydroxide ions in the rainwater?\n"]], ["block_22", ["concentration of hydronium ions in the solution?\n"]], ["block_23", ["regarding: Ca(OH)2, CH3CO2H, HCl, H2CO3, HF, HNO2, HNO3, H3PO4, H2SO4, NH3, NaOH, Na2CO3.\n(a) Identify the strong Br\u00f8nsted-Lowry acids and strong Br\u00f8nsted-Lowry bases.\n(b) Identify the compounds that can behave as Br\u00f8nsted-Lowry acids with strengths lying between those\nof H3Oand H2O.\n(c) Identify the compounds that can behave as Br\u00f8nsted-Lowry bases with strengths lying between those\nof H2O and OH.\n"]], ["block_24", ["descending concentration, all of the ionic and molecular species present in a 1-M aqueous solution of this\nacid.\n"]], ["block_25", ["concentration, all of the ionic and molecular species present in a 1-M aqueous solution of this base.\n"]], ["block_26", ["Magnesia, a suspension of solid Mg(OH)2 in an aqueous medium, is sometimes used to neutralize excess\nstomach acid. Write a complete balanced equation for the neutralization reaction, and identify the\nconjugate acid-base pairs.\n"]], ["block_27", ["that has been used to prevent the growth of algae in swimming pools. Write the balanced chemical\nequation for the reaction of an aqueous solution of HNO3 with CuO.\n"]], ["block_28", ["CH3NH2, Kb = 4.4\n10.\n"]], ["block_29", ["base (CH3)2NH, Kb = 5.9\n10?\n"]], ["block_30", [", is the stronger acid?\n"]]], "page_756": [["block_0", [" 38 . Which is the stronger acid,\nor HBrO?\n"]], ["block_1", [" 39 . Which is the stronger base, (CH3)3N or\n 40 . Predict which acid in each of the following pairs is the stronger and explain your reasoning for each.\n"]], ["block_2", [" 41 . Predict which compound in each of the following pairs of compounds is more acidic and explain your\n"]], ["block_3", [" 42 . Rank the compounds in each of the following groups in order of increasing acidity or basicity, as\n"]], ["block_4", [" 43 . Rank the compounds in each of the following groups in order of increasing acidity or basicity, as\n"]], ["block_5", [" 44 . Both HF and HCN ionize in water to a limited extent. Which of the conjugate bases, For CN, is the\n"]], ["block_6", [" 45 . The active ingredient formed by aspirin in the body is salicylic acid, C6H4OH(CO2H). The carboxyl group\n"]], ["block_7", [" 46 . Are the concentrations of hydronium ion and hydroxide ion in a solution of an acid or a base in water\n"]], ["block_8", [" 47 . What two common assumptions can simplify calculation of equilibrium concentrations in a solution of a\n"]], ["block_9", [" 48 . Which of the following will increase the percent of NH3 that is converted to the ammonium ion in water?\n"]], ["block_10", [" 49 . Which of the following will increase the percentage of HF that is converted to the fluoride ion in water?\n"]], ["block_11", ["(a) H2O or HF\n(b) B(OH)3 or Al(OH)3\n(c)\nor\n"]], ["block_12", ["(d) NH3 or H2S\n(e) H2O or H2Te\n"]], ["block_13", ["reasoning for each.\n(a)\nor\n"]], ["block_14", ["(b) NH3 or H2O\n(c) PH3 or HI\n(d) NH3 or PH3\n(e) H2S or HBr\n"]], ["block_15", ["indicated, and explain the order you assign.\n(a) acidity: HCl, HBr, HI\n(b) basicity: H2O, OH, H, Cl\n"]], ["block_16", ["(c) basicity: Mg(OH)2, Si(OH)4, ClO3(OH) (Hint: Formula could also be written as HClO4.)\n(d) acidity: HF, H2O, NH3, CH4\n"]], ["block_17", ["indicated, and explain the order you assign.\n(a) acidity: NaHSO3, NaHSeO3, NaHSO4\n(b) basicity:\n(c) acidity: HOCl, HOBr, HOI\n(d) acidity: HOCl, HOClO, HOClO2, HOClO3\n(e) basicity:\nHS, HTe,\n"]], ["block_18", ["(f) basicity: BrO,\n"]], ["block_19", ["stronger base?\n"]], ["block_20", ["(\u2212CO2H) acts as a weak acid. The phenol group (an OH group bonded to an aromatic ring) also acts as an\nacid but a much weaker acid. List, in order of descending concentration, all of the ionic and molecular\nspecies present in a 0.001-M aqueous solution of C6H4OH(CO2H).\n"]], ["block_21", ["directly proportional or inversely proportional? Explain your answer.\n"]], ["block_22", ["weak acid or base?\n"]], ["block_23", ["(a) addition of NaOH\n(b) addition of HCl\n(c) addition of NH4Cl\n"]], ["block_24", ["(a) addition of NaOH\n(b) addition of HCl\n(c) addition of NaF\n"]], ["block_25", [" 14 \u2022 Exercises \n 743 \n"]]], "page_757": [["block_0", [" 744 \n 14 \u2022 Exercises \n"]], ["block_1", [" 50 . What is the effect on the concentrations of\nHNO2, and OHwhen the following are added to a\n"]], ["block_2", [" 51 . What is the effect on the concentration of hydrofluoric acid, hydronium ion, and fluoride ion when the\n"]], ["block_3", [" 52 . Why is the hydronium ion concentration in a solution that is 0.10 M in HCl and 0.10 M in HCOOH\n"]], ["block_4", [" 53 . From the equilibrium concentrations given, calculate Ka for each of the weak acids and Kb for each of the\n"]], ["block_5", [" 54 . From the equilibrium concentrations given, calculate Ka for each of the weak acids and Kb for each of the\n"]], ["block_6", [" 55 . Determine Kb for the nitrite ion,\nIn a 0.10-M solution this base is 0.0015% ionized.\n"]], ["block_7", [" 56 . Determine Ka for hydrogen sulfate ion,\nIn a 0.10-M solution the acid is 29% ionized.\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["solution of KNO2 in water:\n(a) HCl\n(b) HNO2\n(c) NaOH\n(d) NaCl\n(e) KNO\n"]], ["block_10", ["following are added to separate solutions of hydrofluoric acid?\n(a) HCl\n(b) KF\n(c) NaCl\n(d) KOH\n(e) HF\n"]], ["block_11", ["determined by the concentration of HCl?\n"]], ["block_12", ["weak bases.\n(a) CH3CO2H:\n= 1.34\n10M;\n"]], ["block_13", ["[CH3CO2H] = 9.866\n10M;\n"]], ["block_14", ["(b) ClO: [OH] = 4.0\n10M;\n"]], ["block_15", ["[HClO] = 2.38\n10M;\n"]], ["block_16", ["[ClO] = 0.273 M;\n(c) HCO2H: [HCO2H] = 0.524 M;\n"]], ["block_17", ["(d)\n= 0.233 M;\n"]], ["block_18", ["[C6H5NH2] = 2.3\n10M;\n"]], ["block_19", ["weak bases.\n(a) NH3: [OH] = 3.1\n10M;\n"]], ["block_20", ["[NH3] = 0.533 M;\n(b) HNO2:\n= 0.011 M;\n"]], ["block_21", ["[HNO2] = 1.07 M;\n(c) (CH3)3N: [(CH3)3N] = 0.25 M;\n[(CH3)3NH] = 4.3\n10M;\n"]], ["block_22", ["[OH] = 3.7\n10M;\n"]], ["block_23", ["(d)\n= 0.100 M;\n"]], ["block_24", ["[NH3] = 7.5\n10M;\n"]], ["block_25", ["[H3O] = 7.5\n10M\n"]], ["block_26", ["= 9.8\n10M;\n"]], ["block_27", ["= 2.3\n10M\n"]], ["block_28", ["= 3.1\n10M;\n"]], ["block_29", ["= 0.0438 M;\n"]], ["block_30", ["= 9.8\n10M;\n"]], ["block_31", ["= 1.34\n10M;\n"]]], "page_758": [["block_0", [" 57 . Calculate the ionization constant for each of the following acids or bases from the ionization constant of its\n"]], ["block_1", [" 58 . Calculate the ionization constant for each of the following acids or bases from the ionization constant of its\n"]], ["block_2", [" 59 . Using the Ka value of 1.4\n10, place\nin the correct location in Figure 14.7.\n"]], ["block_3", [" 60 . Calculate the concentration of all solute species in each of the following solutions of acids or bases.\n"]], ["block_4", [" 61 . Propionic acid, C2H5CO2H (Ka = 1.34\n10), is used in the manufacture of calcium propionate, a food\n"]], ["block_5", [" 62 . White vinegar is a 5.0% by mass solution of acetic acid in water. If the density of white vinegar is 1.007 g/\n"]], ["block_6", [" 63 . The ionization constant of lactic acid, CH3CH(OH)CO2H, an acid found in the blood after strenuous\n"]], ["block_7", [" 64 . Nicotine, C10H14N2, is a base that will accept two protons (Kb1 = 7\n10, Kb2 = 1.4\n10). What is the\n"]], ["block_8", [" 65 . The pH of a 0.23-M solution of HF is 1.92. Determine Ka for HF from these data.\n 66 . The pH of a 0.15-M solution of\nis 1.43. Determine Ka for\nfrom these data.\n"]], ["block_9", [" 67 . The pH of a 0.10-M solution of caffeine is 11.70. Determine Kb for caffeine from these data:\n"]], ["block_10", [" 68 . The pH of a solution of household ammonia, a 0.950 M solution of NH3, is 11.612. Determine Kb for NH3\n"]], ["block_11", [" 14.4 Hydrolysis of Salts \n"]], ["block_12", [" 69 . Determine whether aqueous solutions of the following salts are acidic, basic, or neutral:\n"]], ["block_13", [" 70 . Determine whether aqueous solutions of the following salts are acidic, basic, or neutral:\n"]], ["block_14", ["conjugate base or conjugate acid:\n(a) F\n"]], ["block_15", ["(b)\n(c)\n(d)\n(e)\n(f)\n(as a base)\n"]], ["block_16", ["conjugate base or conjugate acid:\n(a) HTe(as a base)\n(b)\n"]], ["block_17", ["(c)\n(as a base)\n"]], ["block_18", ["(d)\n(as a base)\n"]], ["block_19", ["(e)\n(f)\n(as a base)\n"]], ["block_20", ["Assume that the ionization of water can be neglected, and show that the change in the initial\nconcentrations can be neglected.\n(a) 0.0092 M HClO, a weak acid\n(b) 0.0784 M C6H5NH2, a weak base\n(c) 0.0810 M HCN, a weak acid\n(d) 0.11 M (CH3)3N, a weak base\n(e) 0.120 M\na weak acid, Ka = 1.6\n10\n"]], ["block_21", ["preservative. What is the pH of a 0.698-M solution of C2H5CO2H?\n"]], ["block_22", ["cm, what is the pH?\n"]], ["block_23", ["exercise, is 1.36\n10. If 20.0 g of lactic acid is used to make a solution with a volume of 1.00 L, what is\n"]], ["block_24", ["the concentration of hydronium ion in the solution?\n"]], ["block_25", ["concentration of each species present in a 0.050-M solution of nicotine?\n"]], ["block_26", ["from these data.\n"]], ["block_27", ["(a) Al(NO3)3\n(b) RbI\n(c) KHCO2\n(d) CH3NH3Br\n"]], ["block_28", ["(a) FeCl3\n(b) K2CO3\n(c) NH4Br\n(d) KClO4\n"]], ["block_29", [" 14 \u2022 Exercises \n 745 \n"]]], "page_759": [["block_0", [" 746 \n 14 \u2022 Exercises \n"]], ["block_1", [" 71 . Novocaine, C13H21O2N2Cl, is the salt of the base procaine and hydrochloric acid. The ionization constant\n"]], ["block_2", [" 14.5 Polyprotic Acids \n"]], ["block_3", [" 72 . Which of the following concentrations would be practically equal in a calculation of the equilibrium\n"]], ["block_4", [" 73 . Calculate the concentration of each species present in a 0.050-M solution of H2S.\n 74 . Calculate the concentration of each species present in a 0.010-M solution of phthalic acid, C6H4(CO2H)2.\n"]], ["block_5", [" 75 . Salicylic acid, HOC6H4CO2H, and its derivatives have been used as pain relievers for a long time. Salicylic\n"]], ["block_6", [" 76 . The ion HTeis an amphiprotic species; it can act as either an acid or a base.\n"]], ["block_7", [" 14.6 Buffers \n"]], ["block_8", [" 77 . Explain why a buffer can be prepared from a mixture of NH4Cl and NaOH but not from NH3 and NaOH.\n 78 . Explain why the pH does not change significantly when a small amount of an acid or a base is added to a\n"]], ["block_9", [" 79 . Explain why the pH does not change significantly when a small amount of an acid or a base is added to a\n"]], ["block_10", [" 80 . What is [H3O] in a solution of 0.25 M CH3CO2H and 0.030 M NaCH3CO2?\n"]], ["block_11", [" 81 . What is [H3O] in a solution of 0.075 M HNO2 and 0.030 M NaNO2?\n"]], ["block_12", [" 82 . What is [OH] in a solution of 0.125 M CH3NH2 and 0.130 M CH3NH3Cl?\n"]], ["block_13", [" 83 . What is [OH] in a solution of 1.25 M NH3 and 0.78 M NH4NO3?\n"]], ["block_14", [" 84 . What is the effect on the concentration of acetic acid, hydronium ion, and acetate ion when the following\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["for procaine is 7\n10. Is a solution of novocaine acidic or basic? What are [H3O], [OH], and pH of a\n"]], ["block_17", ["2.0% solution by mass of novocaine, assuming that the density of the solution is 1.0 g/mL.\n"]], ["block_18", ["concentrations in a 0.134-M solution of H2CO3, a diprotic acid:\n[OH], [H2CO3],\n"]], ["block_19", ["acid occurs in small amounts in the leaves, bark, and roots of some vegetation (most notably historically\nin the bark of the willow tree). Extracts of these plants have been used as medications for centuries. The\nacid was first isolated in the laboratory in 1838.\n(a) Both functional groups of salicylic acid ionize in water, with Ka = 1.0\n10for the\u2014CO2H group and\n"]], ["block_20", ["4.2\n10for the \u2212OH group. What is the pH of a saturated solution of the acid (solubility = 1.8 g/L).\n"]], ["block_21", ["(b) Aspirin was discovered as a result of efforts to produce a derivative of salicylic acid that would not be\nirritating to the stomach lining. Aspirin is acetylsalicylic acid, CH3CO2C6H4CO2H. The \u2212CO2H functional\ngroup is still present, but its acidity is reduced, Ka = 3.0\n10. What is the pH of a solution of aspirin\n"]], ["block_22", ["with the same concentration as a saturated solution of salicylic acid (See Part a).\n"]], ["block_23", ["(a) What is Ka for the acid reaction of HTewith H2O?\n(b) What is Kb for the reaction in which HTefunctions as a base in water?\n(c) Demonstrate whether or not the second ionization of H2Te can be neglected in the calculation of [HTe]\nin a 0.10 M solution of H2Te.\n"]], ["block_24", ["solution that contains equal amounts of the acid H3PO4 and a salt of its conjugate base NaH2PO4.\n"]], ["block_25", ["solution that contains equal amounts of the base NH3 and a salt of its conjugate acid NH4Cl.\n"]], ["block_26", ["are added to an acidic buffer solution of equal concentrations of acetic acid and sodium acetate:\n(a) HCl\n(b) KCH3CO2\n(c) NaCl\n(d) KOH\n(e) CH3CO2H\n"]], ["block_27", ["No calculations are needed to answer this question.\n"]]], "page_760": [["block_0", [" 85 . What is the effect on the concentration of ammonia, hydroxide ion, and ammonium ion when the\n"]], ["block_1", [" 86 . What will be the pH of a buffer solution prepared from 0.20 mol NH3, 0.40 mol NH4NO3, and just enough\n"]], ["block_2", [" 87 . Calculate the pH of a buffer solution prepared from 0.155 mol of phosphoric acid, 0.250 mole of KH2PO4,\n"]], ["block_3", [" 88 . How much solid NaCH3CO2\u20223H2O must be added to 0.300 L of a 0.50-M acetic acid solution to give a buffer\n"]], ["block_4", [" 89 . What mass of NH4Cl must be added to 0.750 L of a 0.100-M solution of NH3 to give a buffer solution with a\n"]], ["block_5", [" 90 . A buffer solution is prepared from equal volumes of 0.200 M acetic acid and 0.600 M sodium acetate. Use\n"]], ["block_6", [" 91 . A 5.36\u2013g sample of NH4Cl was added to 25.0 mL of 1.00 M NaOH and the resulting solution\n"]], ["block_7", [" 14.7 Acid-Base Titrations \n"]], ["block_8", [" 92 . Explain how to choose the appropriate acid-base indicator for the titration of a weak base with a strong\n"]], ["block_9", [" 93 . Explain why an acid-base indicator changes color over a range of pH values rather than at a specific pH.\n 94 . Calculate the pH at the following points in a titration of 40 mL (0.040 L) of 0.100 M barbituric acid (Ka = 9.8\n"]], ["block_10", [" 95 . The indicator dinitrophenol is an acid with a Ka of 1.1\n10. In a 1.0\n10-M solution, it is colorless in\n"]], ["block_11", ["following are added to a basic buffer solution of equal concentrations of ammonia and ammonium nitrate:\n(a) KI\n(b) NH3\n(c) HI\n(d) NaOH\n(e) NH4Cl\n"]], ["block_12", ["water to give 1.00 L of solution?\n"]], ["block_13", ["and enough water to make 0.500 L of solution.\n"]], ["block_14", ["with a pH of 5.00? (Hint: Assume a negligible change in volume as the solid is added.)\n"]], ["block_15", ["pH of 9.26? (Hint: Assume a negligible change in volume as the solid is added.)\n"]], ["block_16", ["1.80\n10as Ka for acetic acid.\n"]], ["block_17", ["(a) What is the pH of the solution?\n(b) Is the solution acidic or basic?\n(c) What is the pH of a solution that results when 3.00 mL of 0.034 M HCl is added to 0.200 L of the original\nbuffer?\n"]], ["block_18", ["diluted to 0.100 L.\n(a) What is the pH of this buffer solution?\n(b) Is the solution acidic or basic?\n(c) What is the pH of a solution that results when 3.00 mL of 0.034 M HCl is added to the solution?\n"]], ["block_19", ["acid.\n"]], ["block_20", ["(a) no KOH added\n(b) 20 mL of KOH solution added\n(c) 39 mL of KOH solution added\n(d) 40 mL of KOH solution added\n(e) 41 mL of KOH solution added\n"]], ["block_21", ["acid and yellow in base. Calculate the pH range over which it goes from 10% ionized (colorless) to 90%\nionized (yellow).\n"]], ["block_22", ["10) with 0.100 M KOH.\n"]], ["block_23", [" 14 \u2022 Exercises \n 747 \n"]]], "page_761": [["block_0", [" 748 \n 14 \u2022 Exercises \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_762": [["block_0", ["CHAPTER 15\nEquilibria of Other Reaction Classes\n"]], ["block_1", [{"image_0": "762_0.png", "coords": [72, 104, 622, 358]}]], ["block_2", [" Figure 15.1 \nThe mineral fluorite (CaF2) is formed when dissolved calcium and fluoride ions precipitate from\n"]], ["block_3", ["groundwater within the Earth\u2019s crust. Note that pure fluorite is colorless, and that the color in this sample is due to\nthe presence of other metal ions in the crystal.\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 15.1 Precipitation and Dissolution \n 15.2 Lewis Acids and Bases \n 15.3 Coupled Equilibria \n"]], ["block_6", [" INTRODUCTION \n"]], ["block_7", ["types of jewelry because of its striking appearance. Deposits of fluorite are formed through a process called\nhydrothermal precipitation in which calcium and fluoride ions dissolved in groundwater combine to produce\ninsoluble CaF2 in response to some change in solution conditions. For example, a decrease in temperature\nmay trigger fluorite precipitation if its solubility is exceeded at the lower temperature. Because fluoride ion is a\nweak base, its solubility is also affected by solution pH, and so geologic or other processes that change\ngroundwater pH will also affect the precipitation of fluorite. This chapter extends the equilibrium discussion of\nother chapters by addressing some additional reaction classes (including precipitation) and systems involving\ncoupled equilibrium reactions.\n"]], ["block_8", [" 15.1 Precipitation and Dissolution \n"]], ["block_9", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_10", ["Solubility equilibria are established when the dissolution and precipitation of a solute species occur at equal\n"]], ["block_11", ["\u2022\nWrite chemical equations and equilibrium expressions representing solubility equilibria\n"]], ["block_12", ["\u2022\nCarry out equilibrium computations involving solubility, equilibrium expressions, and solute concentrations\n"]], ["block_13", ["The mineral fluorite, CaF2 Figure 15.1, is commonly used as a semiprecious stone in many\n"]]], "page_763": [["block_0", [" 750 \n 15 \u2022 Equilibria of Other Reaction Classes \n"]], ["block_1", ["The equilibrium constant for solubility equilibria such as this one is called the solubility product constant, \n K sp , in this case\n"]], ["block_2", ["rates. These equilibria underlie many natural and technological processes, ranging from tooth decay to water\npurification. An understanding of the factors affecting compound solubility is, therefore, essential to the\neffective management of these processes. This section applies previously introduced equilibrium concepts\nand tools to systems involving dissolution and precipitation.\n"]], ["block_3", [" The Solubility Product \n"]], ["block_4", ["Recall from the chapter on solutions that the solubility of a substance can vary from essentially zero (insoluble\nor sparingly soluble) to infinity (miscible). A solute with finite solubility can yield a saturated solution when it\nis added to a solvent in an amount exceeding its solubility, resulting in a heterogeneous mixture of the\nsaturated solution and the excess, undissolved solute. For example, a saturated solution of silver chloride is\none in which the equilibrium shown below has been established.\n"]], ["block_5", ["In this solution, an excess of solid AgCl dissolves and dissociates to produce aqueous Agand Clions at the\nsame rate that these aqueous ions combine and precipitate to form solid AgCl (Figure 15.2). Because silver\nchloride is a sparingly soluble salt, the equilibrium concentration of its dissolved ions in the solution is\nrelatively low.\n"]], ["block_6", [" FIGURE 15.2 \nSilver chloride is a sparingly soluble ionic solid. When it is added to water, it dissolves slightly and\n"]], ["block_7", ["produces a mixture consisting of a very dilute solution of Agand Clions in equilibrium with undissolved silver\nchloride.\n"]], ["block_8", ["Recall that only gases and solutes are represented in equilibrium constant expressions, so the Ksp does not\ninclude a term for the undissolved AgCl. A listing of solubility product constants for several sparingly soluble\ncompounds is provided in Appendix J.\n"]], ["block_9", [" Writing Equations and Solubility Products \n"]], ["block_10", ["Write the dissolution equation and the solubility product expression for each of the following slightly soluble\nionic compounds:\n"]], ["block_11", ["(a) AgI, silver iodide, a solid with antiseptic properties\n"]], ["block_12", ["(b) CaCO3, calcium carbonate, the active ingredient in many over-the-counter chewable antacids\n"]], ["block_13", ["(c) Mg(OH)2, magnesium hydroxide, the active ingredient in Milk of Magnesia\n"]], ["block_14", ["(d) Mg(NH4)PO4, magnesium ammonium phosphate, an essentially insoluble substance used in tests for\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["EXAMPLE 15.1\n"]], ["block_17", [{"image_0": "763_0.png", "coords": [130, 292, 481, 433]}]]], "page_764": [["block_0", [" K sp and Solubility \n"]], ["block_1", ["magnesium\n"]], ["block_2", ["(e) Ca5(PO4)3OH, the mineral apatite, a source of phosphate for fertilizers\n"]], ["block_3", [" Solution \n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["Write the dissolution equation and the solubility product for each of the following slightly soluble compounds:\n"]], ["block_6", ["(a) BaSO4\n"]], ["block_7", ["(b) Ag2SO4\n"]], ["block_8", ["(c) Al(OH)3\n"]], ["block_9", ["(d) Pb(OH)Cl\n"]], ["block_10", [" Answer: \n"]], ["block_11", ["The Ksp of a slightly soluble ionic compound may be simply related to its measured solubility provided the\ndissolution process involves only dissociation and solvation, for example:\n"]], ["block_12", ["For cases such as these, one may derive Ksp values from provided solubilities, or vice-versa. Calculations of\nthis sort are most conveniently performed using a compound\u2019s molar solubility, measured as moles of\ndissolved solute per liter of saturated solution.\n"]], ["block_13", [" Calculation of K sp from Equilibrium Concentrations \n"]], ["block_14", ["Fluorite, CaF2, is a slightly soluble solid that dissolves according to the equation:\n"]], ["block_15", ["The concentration of Cain a saturated solution of CaF2 is 2.15\n10M. What is the solubility product of\n"]], ["block_16", ["fluorite?\n"]], ["block_17", [" Solution \n"]], ["block_18", ["According to the stoichiometry of the dissolution equation, the fluoride ion molarity of a CaF2 solution is equal\nto twice its calcium ion molarity:\n"]], ["block_19", ["EXAMPLE 15.2\n"]], ["block_20", [" 15.1 \u2022 Precipitation and Dissolution \n 751 \n"]]], "page_765": [["block_0", [" 752 \n 15 \u2022 Equilibria of Other Reaction Classes \n"]], ["block_1", ["Substituting the ion concentrations into the Ksp expression gives\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["In a saturated solution of Mg(OH)2, the concentration of Mgis 1.31\n10M. What is the solubility product\n"]], ["block_4", ["for Mg(OH)2?\n"]], ["block_5", [" Answer: \n8.99\n10\n"]], ["block_6", [" Determination of Molar Solubility from K sp \nThe Ksp of copper(I) bromide, CuBr, is 6.3\n10. Calculate the molar solubility of copper bromide.\n"]], ["block_7", [" Solution \n"]], ["block_8", ["The dissolution equation and solubility product expression are\n"]], ["block_9", ["Following the ICE approach to this calculation yields the table\n"]], ["block_10", [{"image_0": "765_0.png", "coords": [72, 374, 423, 469]}]], ["block_11", ["Substituting the equilibrium concentration terms into the solubility product expression and solving for x\nyields\n"]], ["block_12", ["Since the dissolution stoichiometry shows one mole of copper(I) ion and one mole of bromide ion are produced\nfor each moles of Br dissolved, the molar solubility of CuBr is 7.9\n10M.\n"]], ["block_13", [" Check Your Learning \n"]], ["block_14", ["The Ksp of AgI is 1.5\n10. Calculate the molar solubility of silver iodide.\n"]], ["block_15", [" Answer: \n1.2\n10M\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["EXAMPLE 15.3\n"]]], "page_766": [["block_0", [" Determination of Molar Solubility from K sp \nThe Ksp of calcium hydroxide, Ca(OH)2, is 1.3\n10. Calculate the molar solubility of calcium hydroxide.\n"]], ["block_1", [" Solution \n"]], ["block_2", ["The dissolution equation and solubility product expression are\n"]], ["block_3", ["The ICE table for this system is\n"]], ["block_4", [{"image_0": "766_0.png", "coords": [72, 220, 423, 315]}]], ["block_5", ["Substituting terms for the equilibrium concentrations into the solubility product expression and solving for x\ngives\n"]], ["block_6", ["As defined in the ICE table, x is the molarity of calcium ion in the saturated solution. The dissolution\nstoichiometry shows a 1:1 relation between moles of calcium ion in solution and moles of compound\ndissolved, and so, the molar solubility of Ca(OH)2 is 6.9\n10M.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["The Ksp of PbI2 is 1.4\n10. Calculate the molar solubility of lead(II) iodide.\n"]], ["block_9", [" Answer: \n1.5\n10M\n"]], ["block_10", [" Determination of K sp from Gram Solubility \n"]], ["block_11", ["Many of the pigments used by artists in oil-based paints (Figure 15.3) are sparingly soluble in water. For\nexample, the solubility of the artist\u2019s pigment chrome yellow, PbCrO4, is 4.6\n10g/L. Determine the\n"]], ["block_12", ["solubility product for PbCrO4.\n"]], ["block_13", ["EXAMPLE 15.4\n"]], ["block_14", ["EXAMPLE 15.5\n"]], ["block_15", [" 15.1 \u2022 Precipitation and Dissolution \n 753 \n"]]], "page_767": [["block_0", [" 754 \n 15 \u2022 Equilibria of Other Reaction Classes \n"]], ["block_1", ["Ksp = [Pb]\n= (1.4\n10)(1.4\n10) = 2.0\n10\n"]], ["block_2", [" FIGURE 15.3 \nOil paints contain pigments that are very slightly soluble in water. In addition to chrome yellow\n"]], ["block_3", ["(PbCrO4), examples include Prussian blue (Fe7(CN)18), the reddish-orange color vermilion (HgS), and green color\nveridian (Cr2O3). (credit: Sonny Abesamis)\n"]], ["block_4", [" Solution \n"]], ["block_5", ["Before calculating the solubility product, the provided solubility must be converted to molarity:\n"]], ["block_6", ["The dissolution equation for this compound is\n"]], ["block_7", ["The dissolution stoichiometry shows a 1:1 relation between the molar amounts of compound and its two ions,\nand so both [Pb] and\nare equal to the molar solubility of PbCrO4:\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["The solubility of TlCl [thallium(I) chloride], an intermediate formed when thallium is being isolated from ores,\nis 3.12 grams per liter at 20 \u00b0C. What is its solubility product?\n"]], ["block_10", [" Answer: \n1.69\n10\n"]], ["block_11", [" Calculating the Solubility of Hg 2 Cl 2 \nCalomel, Hg2Cl2, is a compound composed of the diatomic ion of mercury(I),\nand chloride ions, Cl.\n"]], ["block_12", ["Although most mercury compounds are now known to be poisonous, eighteenth-century physicians used\ncalomel as a medication. Their patients rarely suffered any mercury poisoning from the treatments because\ncalomel has a very low solubility, as suggested by its very small Ksp:\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", ["EXAMPLE 15.6\n"]], ["block_15", [{"image_0": "767_0.png", "coords": [189, 57, 423, 213]}]]], "page_768": [["block_0", ["Calculate the molar solubility of Hg2Cl2.\n"]], ["block_1", [" Solution \n"]], ["block_2", ["The dissolution stoichiometry shows a 1:1 relation between the amount of compound dissolved and the\namount of mercury(I) ions, and so the molar solubility of Hg2Cl2 is equal to the concentration of\nions\n"]], ["block_3", ["Following the ICE approach results in\n"]], ["block_4", [{"image_0": "768_0.png", "coords": [72, 143, 423, 238]}]], ["block_5", ["Substituting the equilibrium concentration terms into the solubility product expression and solving for x gives\n"]], ["block_6", ["The dissolution stoichiometry shows the molar solubility of Hg2Cl2 is equal to\nor 6.5\n10M.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["Determine the molar solubility of MgF2 from its solubility product: Ksp = 6.4\n10.\n"]], ["block_9", [" Answer: \n1.2\n10M\n"]], ["block_10", [" Using Barium Sulfate for Medical Imaging \nVarious types of medical imaging techniques are used to aid diagnoses of illnesses in a noninvasive manner.\nOne such technique utilizes the ingestion of a barium compound before taking an X-ray image. A suspension of\nbarium sulfate, a chalky powder, is ingested by the patient. Since the Ksp of barium sulfate is 2.3\n10, very\n"]], ["block_11", ["little of it dissolves as it coats the lining of the patient\u2019s intestinal tract. Barium-coated areas of the digestive\ntract then appear on an X-ray as white, allowing for greater visual detail than a traditional X-ray (Figure 15.4).\n"]], ["block_12", ["HOW SCIENCES INTERCONNECT\n"]], ["block_13", [" 15.1 \u2022 Precipitation and Dissolution \n 755 \n"]]], "page_769": [["block_0", [" 756 \n 15 \u2022 Equilibria of Other Reaction Classes \n"]], ["block_1", ["Qsp < Ksp: the reaction proceeds in the forward direction (solution is not saturated; no precipitation observed)\n"]], ["block_2", ["Qsp > Ksp: the reaction proceeds in the reverse direction (solution is supersaturated; precipitation will occur)\n"]], ["block_3", [" FIGURE 15.4 \nA suspension of barium sulfate coats the intestinal tract, permitting greater visual detail than a\n"]], ["block_4", ["traditional X-ray. (credit modification of work by \u201cglitzy queen00\u201d/Wikimedia Commons)\n"]], ["block_5", ["Medical imaging using barium sulfate can be used to diagnose acid reflux disease, Crohn\u2019s disease, and ulcers\nin addition to other conditions.\n"]], ["block_6", ["Visit this website (http://openstax.org/l/16barium) for more information on how barium is used in medical\ndiagnoses and which conditions it is used to diagnose.\n"]], ["block_7", [" Predicting Precipitation \n"]], ["block_8", ["The equation that describes the equilibrium between solid calcium carbonate and its solvated ions is:\n"]], ["block_9", ["It is important to realize that this equilibrium is established in any aqueous solution containing Caand CO3\n"]], ["block_10", ["ions, not just in a solution formed by saturating water with calcium carbonate. Consider, for example, mixing\naqueous solutions of the soluble compounds sodium carbonate and calcium nitrate. If the concentrations of\ncalcium and carbonate ions in the mixture do not yield a reaction quotient, Qsp, that exceeds the solubility\nproduct, Ksp, then no precipitation will occur. If the ion concentrations yield a reaction quotient greater than\nthe solubility product, then precipitation will occur, lowering those concentrations until equilibrium is\nestablished (Qsp = Ksp). The comparison of Qsp to Ksp to predict precipitation is an example of the general\napproach to predicting the direction of a reaction first introduced in the chapter on equilibrium. For the\nspecific case of solubility equilibria:\n"]], ["block_11", ["This predictive strategy and related calculations are demonstrated in the next few example exercises.\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", [{"image_0": "769_0.png", "coords": [189, 57, 423, 393]}]]], "page_770": [["block_0", [" Precipitation of Mg(OH) 2 \nThe first step in the preparation of magnesium metal is the precipitation of Mg(OH)2 from sea water by the\naddition of lime, Ca(OH)2, a readily available inexpensive source of OHion:\n"]], ["block_1", ["The concentration of Mg(aq) in sea water is 0.0537 M. Will Mg(OH)2 precipitate when enough Ca(OH)2 is\nadded to give a [OH] of 0.0010 M?\n"]], ["block_2", [" Solution \n"]], ["block_3", ["Calculation of the reaction quotient under these conditions is shown here:\n"]], ["block_4", ["Because Q is greater than Ksp (Q = 5.4\n10is larger than Ksp = 8.9\n10), the reverse reaction will proceed,\n"]], ["block_5", ["precipitating magnesium hydroxide until the dissolved ion concentrations have been sufficiently lowered, so\nthat Qsp = Ksp.\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["Predict whether CaHPO4 will precipitate from a solution with [Ca] = 0.0001 M and\n= 0.001 M.\n"]], ["block_8", [" Answer: \nNo precipitation of CaHPO4; Q = 1\n10, which is less than Ksp (7 \u00d7 10)\n"]], ["block_9", [" Precipitation of AgCl \n"]], ["block_10", ["Does silver chloride precipitate when equal volumes of a 2.0\n10-M solution of AgNO3 and a 2.0\n10-M\n"]], ["block_11", ["solution of NaCl are mixed?\n"]], ["block_12", [" Solution \n"]], ["block_13", ["The equation for the equilibrium between solid silver chloride, silver ion, and chloride ion is:\n"]], ["block_14", ["The solubility product is 1.6\n10(see Appendix J).\n"]], ["block_15", ["AgCl will precipitate if the reaction quotient calculated from the concentrations in the mixture of AgNO3 and\nNaCl is greater than Ksp. Because the volume doubles when equal volumes of AgNO3 and NaCl solutions are\nmixed, each concentration is reduced to half its initial value\n"]], ["block_16", ["The reaction quotient, Q, is greater than Ksp for AgCl, so a supersaturated solution is formed:\n"]], ["block_17", ["AgCl will precipitate from the mixture until the dissolution equilibrium is established, with Q equal to Ksp.\n"]], ["block_18", [" Check Your Learning \n"]], ["block_19", ["Will KClO4 precipitate when 20 mL of a 0.050-M solution of Kis added to 80 mL of a 0.50-M solution of\n"]], ["block_20", ["the mixture.)\n"]], ["block_21", ["EXAMPLE 15.7\n"]], ["block_22", ["EXAMPLE 15.8\n"]], ["block_23", ["(Hint: Use the dilution equation to calculate the concentrations of potassium and perchlorate ions in\n"]], ["block_24", [" 15.1 \u2022 Precipitation and Dissolution \n 757 \n"]]], "page_771": [["block_0", [" 758 \n 15 \u2022 Equilibria of Other Reaction Classes \n"]], ["block_1", [" Answer: \nNo, Q = 4.0\n10, which is less than Ksp = 1.05\n10\n"]], ["block_2", [" Precipitation of Calcium Oxalate \n"]], ["block_3", ["Blood will not clot if calcium ions are removed from its plasma. Some blood collection tubes contain salts of\nthe oxalate ion,\nfor this purpose (Figure 15.5). At sufficiently high concentrations, the calcium and\n"]], ["block_4", ["oxalate ions form solid, CaC2O4\u00b7H2O (calcium oxalate monohydrate). The concentration of Cain a sample of\nblood serum is 2.2\n10M. What concentration of\nion must be established before CaC2O4\u00b7H2O\n"]], ["block_5", ["begins to precipitate?\n"]], ["block_6", [" FIGURE 15.5 \nAnticoagulants can be added to blood that will combine with the Caions in blood serum and\n"]], ["block_7", ["prevent the blood from clotting. (credit: modification of work by Neeta Lind)\n"]], ["block_8", [" Solution \n"]], ["block_9", ["The equilibrium expression is:\n"]], ["block_10", ["For this reaction:\n"]], ["block_11", ["(see Appendix J)\n"]], ["block_12", ["Substitute the provided calcium ion concentration into the solubility product expression and solve for oxalate\nconcentration:\n"]], ["block_13", ["A concentration of\n= 8.9\n10M is necessary to initiate the precipitation of CaC2O4 under these\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["EXAMPLE 15.9\n"]], ["block_16", [{"image_0": "771_0.png", "coords": [189, 224, 423, 452]}]]], "page_772": [["block_0", ["conditions.\n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["If a solution contains 0.0020 mol of\nper liter, what concentration of Agion must be reached by adding\n"]], ["block_3", ["solid AgNO3 before Ag2CrO4 begins to precipitate? Neglect any increase in volume upon adding the solid silver\nnitrate.\n"]], ["block_4", [" Answer: \n6.7\n10M\n"]], ["block_5", [" Concentrations Following Precipitation \n"]], ["block_6", ["Clothing washed in water that has a manganese [Mn(aq)] concentration exceeding 0.1 mg/L (1.8\n10M)\n"]], ["block_7", ["may be stained by the manganese upon oxidation, but the amount of Mnin the water can be decreased by\nadding a base to precipitate Mn(OH)2. What pH is required to keep [Mn] equal to 1.8\n10M?\n"]], ["block_8", [" Solution \n"]], ["block_9", ["The dissolution of Mn(OH)2 is described by the equation:\n"]], ["block_10", ["At equilibrium:\n"]], ["block_11", ["or\n"]], ["block_12", ["so\n"]], ["block_13", ["Calculate the pH from the pOH:\n"]], ["block_14", ["(final result rounded to one significant digit, limited by the certainty of the Ksp)\n"]], ["block_15", [" Check Your Learning \n"]], ["block_16", ["The first step in the preparation of magnesium metal is the precipitation of Mg(OH)2 from sea water by the\naddition of Ca(OH)2. The concentration of Mg(aq) in sea water is 5.37\n10M. Calculate the pH at which\n"]], ["block_17", ["[Mg] is decreased to 1.0\n10M\n"]], ["block_18", [" Answer: \n10.97\n"]], ["block_19", ["In solutions containing two or more ions that may form insoluble compounds with the same counter ion, an\nexperimental strategy called selective precipitation may be used to remove individual ions from solution. By\nincreasing the counter ion concentration in a controlled manner, ions in solution may be precipitated\nindividually, assuming their compound solubilities are adequately different. In solutions with equal\nconcentrations of target ions, the ion forming the least soluble compound will precipitate first (at the lowest\nconcentration of counter ion), with the other ions subsequently precipitating as their compound\u2019s solubilities\nare reached. As an illustration of this technique, the next example exercise describes separation of a two halide\nions via precipitation of one as a silver salt.\n"]], ["block_20", ["EXAMPLE 15.10\n"]], ["block_21", [" 15.1 \u2022 Precipitation and Dissolution \n 759 \n"]]], "page_773": [["block_0", [" 760 \n 15 \u2022 Equilibria of Other Reaction Classes \n"]], ["block_1", [" Precipitation of Silver Halides \n"]], ["block_2", ["A solution contains 0.00010 mol of KBr and 0.10 mol of KCl per liter. AgNO3 is gradually added to this solution.\nWhich forms first, solid AgBr or solid AgCl?\n"]], ["block_3", [" Solution \n"]], ["block_4", ["The two equilibria involved are:\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", ["Chemistry in Everyday Life\n"]], ["block_7", [" The Role of Precipitation in Wastewater Treatment \nSolubility equilibria are useful tools in the treatment of wastewater carried out in facilities that may treat\nthe municipal water in your city or town (Figure 15.6). Specifically, selective precipitation is used to remove\ncontaminants from wastewater before it is released back into natural bodies of water. For example,\nphosphate ions\nare often present in the water discharged from manufacturing facilities. An\n"]], ["block_8", ["abundance of phosphate causes excess algae to grow, which impacts the amount of oxygen available for\nmarine life as well as making water unsuitable for human consumption.\n"]], ["block_9", [" FIGURE 15.6 \nWastewater treatment facilities, such as this one, remove contaminants from wastewater before\n"]], ["block_10", ["the water is released back into the natural environment. (credit: \u201ceutrophication&hypoxia\u201d/Wikimedia\nCommons)\n"]], ["block_11", ["One common way to remove phosphates from water is by the addition of calcium hydroxide, or lime,\nCa(OH)2. As the water is made more basic, the calcium ions react with phosphate ions to produce\nhydroxylapatite, Ca5(PO4)3OH, which then precipitates out of the solution:\n"]], ["block_12", ["Because the amount of calcium ion added does not result in exceeding the solubility products for other\ncalcium salts, the anions of those salts remain behind in the wastewater. The precipitate is then removed\nby filtration and the water is brought back to a neutral pH by the addition of CO2 in a recarbonation\nprocess. Other chemicals can also be used for the removal of phosphates by precipitation, including\niron(III) chloride and aluminum sulfate.\n"]], ["block_13", ["View this site (http://openstax.org/l/16Wastewater) for more information on how phosphorus is removed\nfrom wastewater.\n"]], ["block_14", ["EXAMPLE 15.11\n"]], ["block_15", [{"image_0": "773_0.png", "coords": [189, 181, 423, 339]}]]], "page_774": [["block_0", ["Compared with pure water, the solubility of an ionic compound is less in aqueous solutions containing a\ncommon ion (one also produced by dissolution of the ionic compound). This is an example of a phenomenon\nknown as the common ion effect , which is a consequence of the law of mass action that may be explained\nusing Le Ch\u00c2telier\u2019s principle. Consider the dissolution of silver iodide:\n"]], ["block_1", ["The mathematical product of silver(I) and iodide ion molarities is constant in an equilibrium mixture\nregardless of the source of the ions, and so an increase in one ion\u2019s concentration must be balanced by a\nproportional decrease in the other.\n"]], ["block_2", ["If the solution contained about equal concentrations of Cland Br, then the silver salt with the smaller Ksp\n(AgBr) would precipitate first. The concentrations are not equal, however, so the [Ag] at which AgCl begins to\nprecipitate and the [Ag] at which AgBr begins to precipitate must be calculated. The salt that forms at the\nlower [Ag] precipitates first.\n"]], ["block_3", ["AgBr precipitates when Q equals Ksp for AgBr\n"]], ["block_4", ["AgBr begins to precipitate when [Ag] is 5.0\n10M.\n"]], ["block_5", ["For AgCl: AgCl precipitates when Q equals Ksp for AgCl (1.6\n10). When [Cl] = 0.10 M:\n"]], ["block_6", ["AgCl begins to precipitate when [Ag] is 1.6\n10M.\n"]], ["block_7", ["AgCl begins to precipitate at a lower [Ag] than AgBr, so AgCl begins to precipitate first. Note the chloride ion\nconcentration of the initial mixture was significantly greater than the bromide ion concentration, and so silver\nchloride precipitated first despite having a Ksp greater than that of silver bromide.\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["If silver nitrate solution is added to a solution which is 0.050 M in both Cland Brions, at what [Ag] would\nprecipitation begin, and what would be the formula of the precipitate?\n"]], ["block_10", [" Answer: \n[Ag] = 1.0\n10M; AgBr precipitates first\n"]], ["block_11", [" Common Ion Effect \n"]], ["block_12", ["This solubility equilibrium may be shifted left by the addition of either silver(I) or iodide ions, resulting in the\nprecipitation of AgI and lowered concentrations of dissolved Agand I. In solutions that already contain either\nof these ions, less AgI may be dissolved than in solutions without these ions.\n"]], ["block_13", ["This effect may also be explained in terms of mass action as represented in the solubility product expression:\n"]], ["block_14", ["View this simulation (http://openstax.org/l/16solublesalts) to explore various aspects of the common ion effect.\n"]], ["block_15", ["LINK TO LEARNING\n"]], ["block_16", [" 15.1 \u2022 Precipitation and Dissolution \n 761 \n"]]], "page_775": [["block_0", [" 762 \n 15 \u2022 Equilibria of Other Reaction Classes \n"]], ["block_1", [" Common Ion Effect on Solubility \n"]], ["block_2", ["What is the effect on the amount of solid Mg(OH)2 and the concentrations of Mgand OHwhen each of the\nfollowing are added to a saturated solution of Mg(OH)2?\n"]], ["block_3", ["(a) MgCl2\n"]], ["block_4", ["(b) KOH\n"]], ["block_5", ["(c) NaNO3\n"]], ["block_6", ["(d) Mg(OH)2\n"]], ["block_7", [" Solution \n"]], ["block_8", ["The solubility equilibrium is\n"]], ["block_9", ["(a) Adding a common ion, Mg, will increase the concentration of this ion and shift the solubility equilibrium\nto the left, decreasing the concentration of hydroxide ion and increasing the amount of undissolved\nmagnesium hydroxide.\n"]], ["block_10", ["(b) Adding a common ion, OH, will increase the concentration of this ion and shift the solubility equilibrium to\nthe left, decreasing the concentration of magnesium ion and increasing the amount of undissolved\nmagnesium hydroxide.\n"]], ["block_11", ["(c) The added compound does not contain a common ion, and no effect on the magnesium hydroxide solubility\nequilibrium is expected.\n"]], ["block_12", ["(d) Adding more solid magnesium hydroxide will increase the amount of undissolved compound in the\nmixture. The solution is already saturated, though, so the concentrations of dissolved magnesium and\nhydroxide ions will remain the same.\n"]], ["block_13", ["Thus, changing the amount of solid magnesium hydroxide in the mixture has no effect on the value of Q, and\nno shift is required to restore Q to the value of the equilibrium constant.\n"]], ["block_14", [" Check Your Learning \n"]], ["block_15", ["What is the effect on the amount of solid NiCO3 and the concentrations of Niand\nwhen each of the\n"]], ["block_16", ["following are added to a saturated solution of NiCO3\n"]], ["block_17", ["(a) Ni(NO3)2\n"]], ["block_18", ["(b) KClO4\n"]], ["block_19", ["(c) NiCO3\n"]], ["block_20", ["(d) K2CO3\n"]], ["block_21", [" Answer: \n"]], ["block_22", ["(a) mass of NiCO3(s) increases, [Ni] increases,\ndecreases; (b) no appreciable effect; (c) no effect\n"]], ["block_23", ["except to increase the amount of solid NiCO3; (d) mass of NiCO3(s) increases, [Ni] decreases,\nincreases;\n"]], ["block_24", [" Access for free at openstax.org \n"]], ["block_25", ["EXAMPLE 15.12\n"]]], "page_776": [["block_0", [" Common Ion Effect \n"]], ["block_1", ["Calculate the molar solubility of cadmium sulfide (CdS) in a 0.010-M solution of cadmium bromide (CdBr2).\nThe Ksp of CdS is 1.0\n10.\n"]], ["block_2", [" Solution \n"]], ["block_3", ["This calculation can be performed using the ICE approach:\n"]], ["block_4", [{"image_0": "776_0.png", "coords": [72, 191, 423, 286]}]], ["block_5", ["Because Ksp is very small, assume x << 0.010 and solve the simplified equation for x:\n"]], ["block_6", ["The molar solubility of CdS in this solution is 1.0\n10M.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["Calculate the molar solubility of aluminum hydroxide, Al(OH)3, in a 0.015-M solution of aluminum nitrate,\nAl(NO3)3. The Ksp of Al(OH)3 is 2\n10.\n"]], ["block_9", [" Answer: \n4\n10M\n"]], ["block_10", [" 15.2 Lewis Acids and Bases \n"]], ["block_11", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_12", ["In 1923, G. N. Lewis proposed a generalized definition of acid-base behavior in which acids and bases are\nidentified by their ability to accept or to donate a pair of electrons and form a coordinate covalent bond.\n"]], ["block_13", ["A coordinate covalent bond (or dative bond) occurs when one of the atoms in the bond provides both bonding\nelectrons. For example, a coordinate covalent bond occurs when a water molecule combines with a hydrogen\nion to form a hydronium ion. A coordinate covalent bond also results when an ammonia molecule combines\nwith a hydrogen ion to form an ammonium ion. Both of these equations are shown here.\n"]], ["block_14", ["\u2022\nExplain the Lewis model of acid-base chemistry\n"]], ["block_15", ["\u2022\nWrite equations for the formation of adducts and complex ions\n"]], ["block_16", ["\u2022\nPerform equilibrium calculations involving formation constants\n"]], ["block_17", ["EXAMPLE 15.13\n"]], ["block_18", [" 15.2 \u2022 Lewis Acids and Bases \n 763 \n"]]], "page_777": [["block_0", [" 764 \n 15 \u2022 Equilibria of Other Reaction Classes \n"]], ["block_1", [{"image_0": "777_0.png", "coords": [72, 57, 423, 181]}]], ["block_2", ["Reactions involving the formation of coordinate covalent bonds are classified as Lewis acid-base chemistry .\nThe species donating the electron pair that compose the bond is a Lewis base , the species accepting the\nelectron pair is a Lewis acid , and the product of the reaction is a Lewis acid-base adduct . As the two examples\nabove illustrate, Br\u00f8nsted-Lowry acid-base reactions represent a subcategory of Lewis acid reactions,\nspecifically, those in which the acid species is H. A few examples involving other Lewis acids and bases are\ndescribed below.\n"]], ["block_3", ["The boron atom in boron trifluoride, BF3, has only six electrons in its valence shell. Being short of the\npreferred octet, BF3 is a very good Lewis acid and reacts with many Lewis bases; a fluoride ion is the Lewis\nbase in this reaction, donating one of its lone pairs:\n"]], ["block_4", [{"image_1": "777_1.png", "coords": [72, 310, 306, 398]}]], ["block_5", ["In the following reaction, each of two ammonia molecules, Lewis bases, donates a pair of electrons to a silver\nion, the Lewis acid:\n"]], ["block_6", [{"image_2": "777_2.png", "coords": [72, 433, 423, 522]}]], ["block_7", ["Nonmetal oxides act as Lewis acids and react with oxide ions, Lewis bases, to form oxyanions:\n"]], ["block_8", [{"image_3": "777_3.png", "coords": [72, 544, 423, 633]}]], ["block_9", ["Many Lewis acid-base reactions are displacement reactions in which one Lewis base displaces another Lewis\nbase from an acid-base adduct, or in which one Lewis acid displaces another Lewis acid:\n"]], ["block_10", [" Access for free at openstax.org \n"]]], "page_778": [["block_0", [{"image_0": "778_0.png", "coords": [72, 57, 540, 251]}]], ["block_1", ["Another type of Lewis acid-base chemistry involves the formation of a complex ion (or a coordination complex)\ncomprising a central atom, typically a transition metal cation, surrounded by ions or molecules called ligands .\nThese ligands can be neutral molecules like H2O or NH3, or ions such as CNor OH. Often, the ligands act as\nLewis bases, donating a pair of electrons to the central atom. These types of Lewis acid-base reactions are\nexamples of a broad subdiscipline called coordination chemistry\u2014the topic of another chapter in this text.\n"]], ["block_2", ["The equilibrium constant for the reaction of a metal ion with one or more ligands to form a coordination\ncomplex is called a formation constant (K f ) (sometimes called a stability constant). For example, the complex\nion\n"]], ["block_3", [{"image_1": "778_1.png", "coords": [72, 367, 189, 383]}]], ["block_4", ["is produced by the reaction\n"]], ["block_5", ["The formation constant for this reaction is\n"]], ["block_6", ["Alternatively, the reverse reaction (decomposition of the complex ion) can be considered, in which case the\nequilibrium constant is a dissociation constant (K d ) . Per the relation between equilibrium constants for\nreciprocal reactions described, the dissociation constant is the mathematical inverse of the formation\nconstant, Kd = Kf. A tabulation of formation constants is provided in Appendix K.\n"]], ["block_7", ["As an example of dissolution by complex ion formation, let us consider what happens when we add aqueous\nammonia to a mixture of silver chloride and water. Silver chloride dissolves slightly in water, giving a small\nconcentration of Ag([Ag] = 1.3\n10M):\n"]], ["block_8", ["However, if NH3 is present in the water, the complex ion,\ncan form according to the equation:\n"]], ["block_9", ["with\n"]], ["block_10", ["The large size of this formation constant indicates that most of the free silver ions produced by the dissolution\nof AgCl combine with NH 3 to form\nAs a consequence, the concentration of silver ions, [Ag ], is\n"]], ["block_11", ["reduced, and the reaction quotient for the dissolution of silver chloride, [Ag ][Cl ], falls below the solubility\n"]], ["block_12", [" 15.2 \u2022 Lewis Acids and Bases \n 765 \n"]]], "page_779": [["block_0", [" 766 \n 15 \u2022 Equilibria of Other Reaction Classes \n"]], ["block_1", ["product of AgCl:\n"]], ["block_2", ["More silver chloride then dissolves. If the concentration of ammonia is great enough, all of the silver chloride\ndissolves.\n"]], ["block_3", [" Dissociation of a Complex Ion \n"]], ["block_4", ["Calculate the concentration of the silver ion in a solution that initially is 0.10 M with respect to\n"]], ["block_5", [" Solution \n"]], ["block_6", ["Applying the standard ICE approach to this reaction yields the following:\n"]], ["block_7", [{"image_0": "779_0.png", "coords": [72, 230, 423, 325]}]], ["block_8", ["Substituting these equilibrium concentration terms into the Kf expression gives\n"]], ["block_9", ["The very large equilibrium constant means the amount of the complex ion that will dissociate, x, will be very\nsmall. Assuming x << 0.1 permits simplifying the above equation:\n"]], ["block_10", ["Because only 1.1% of the\ndissociates into Agand NH3, the assumption that x is small is justified.\n"]], ["block_11", ["Using this value of x and the relations in the above ICE table allows calculation of all species\u2019 equilibrium\nconcentrations:\n"]], ["block_12", ["The concentration of free silver ion in the solution is 0.0011 M.\n"]], ["block_13", [" Check Your Learning \n"]], ["block_14", ["Calculate the silver ion concentration, [Ag], of a solution prepared by dissolving 1.00 g of AgNO3 and 10.0 g of\nKCN in sufficient water to make 1.00 L of solution. (Hint: Because Kf is very large, assume the reaction goes to\ncompletion then calculate the [Ag] produced by dissociation of the complex.)\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["EXAMPLE 15.14\n"]]], "page_780": [["block_0", [" Answer: \n2.9\n10M\n"]], ["block_1", [" 15.3 Coupled Equilibria \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["As discussed in preceding chapters on equilibrium, coupled equilibria involve two or more separate chemical\nreactions that share one or more reactants or products. This section of this chapter will address solubility\nequilibria coupled with acid-base and complex-formation reactions.\n"]], ["block_4", ["An environmentally relevant example illustrating the coupling of solubility and acid-base equilibria is the\nimpact of ocean acidification on the health of the ocean\u2019s coral reefs. These reefs are built upon skeletons of\nsparingly soluble calcium carbonate excreted by colonies of corals (small marine invertebrates). The relevant\ndissolution equilibrium is\n"]], ["block_5", ["Rising concentrations of atmospheric carbon dioxide contribute to an increased acidity of ocean waters due to\nthe dissolution, hydrolysis, and acid ionization of carbon dioxide:\n"]], ["block_6", ["Inspection of these equilibria shows the carbonate ion is involved in the calcium carbonate dissolution and the\nacid hydrolysis of bicarbonate ion. Combining the dissolution equation with the reverse of the acid hydrolysis\nequation yields\n"]], ["block_7", ["The equilibrium constant for this net reaction is much greater than the Ksp for calcium carbonate, indicating\nits solubility is markedly increased in acidic solutions. As rising carbon dioxide levels in the atmosphere\nincrease the acidity of ocean waters, the calcium carbonate skeletons of coral reefs become more prone to\ndissolution and subsequently less healthy (Figure 15.7).\n"]], ["block_8", [" FIGURE 15.7 \nHealthy coral reefs (a) support a dense and diverse array of sea life across the ocean food chain. But\n"]], ["block_9", ["when coral are unable to adequately build and maintain their calcium carbonate skeletons because of excess ocean\nacidification, the unhealthy reef (b) is only capable of hosting a small fraction of the species as before, and the local\nfood chain starts to collapse. (credit a: modification of work by NOAA Photo Library; credit b: modification of work by\n"]], ["block_10", ["\u2022\nDescribe examples of systems involving two (or more) coupled chemical equilibria\n"]], ["block_11", ["\u2022\nCalculate reactant and product concentrations for coupled equilibrium systems\n"]], ["block_12", [{"image_0": "780_0.png", "coords": [130, 531, 481, 670]}]], ["block_13", [" 15.3 \u2022 Coupled Equilibria \n 767 \n"]]], "page_781": [["block_0", [" 768 \n 15 \u2022 Equilibria of Other Reaction Classes \n"]], ["block_1", ["\u201cprilfish\u201d/Flickr)\n"]], ["block_2", ["Learn more about ocean acidification (http://openstax.org/l/16acidicocean) and how it affects other marine\ncreatures.\n"]], ["block_3", ["This site (http://openstax.org/l/16coralreef) has detailed information about how ocean acidification specifically\naffects coral reefs.\n"]], ["block_4", ["The dramatic increase in solubility with increasing acidity described above for calcium carbonate is typical of\nsalts containing basic anions (e.g., carbonate, fluoride, hydroxide, sulfide). Another familiar example is the\nformation of dental cavities in tooth enamel. The major mineral component of enamel is calcium\nhydroxyapatite (Figure 15.8), a sparingly soluble ionic compound whose dissolution equilibrium is\n"]], ["block_5", [" FIGURE 15.8 \nCrystal of the mineral hydroxyapatite, Ca5(PO4)3OH, is shown here. The pure compound is white, but\n"]], ["block_6", ["like many other minerals, this sample is colored because of the presence of impurities.\n"]], ["block_7", ["This compound dissolved to yield two different basic ions: triprotic phosphate ions\n"]], ["block_8", ["and monoprotic hydroxide ions:\n"]], ["block_9", ["Of the two basic productions, the hydroxide is, of course, by far the stronger base (it\u2019s the strongest base that\ncan exist in aqueous solution), and so it is the dominant factor providing the compound an acid-dependent\nsolubility. Dental cavities form when the acid waste of bacteria growing on the surface of teeth hastens the\ndissolution of tooth enamel by reacting completely with the strong base hydroxide, shifting the hydroxyapatite\nsolubility equilibrium to the right. Some toothpastes and mouth rinses contain added NaF or SnF2 that make\nenamel more acid resistant by replacing the strong base hydroxide with the weak base fluoride:\n"]], ["block_10", ["The weak base fluoride ion reacts only partially with the bacterial acid waste, resulting in a less extensive shift\nin the solubility equilibrium and an increased resistance to acid dissolution. See the Chemistry in Everyday\nLife feature on the role of fluoride in preventing tooth decay for more information.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["LINK TO LEARNING\n"]], ["block_13", [{"image_0": "781_0.png", "coords": [189, 250, 423, 388]}]]], "page_782": [["block_0", ["The solubility of ionic compounds may also be increased when dissolution is coupled to the formation of a\ncomplex ion. For example, aluminum hydroxide dissolves in a solution of sodium hydroxide or another strong\nbase because of the formation of the complex ion\n"]], ["block_1", [{"image_0": "782_0.png", "coords": [72, 471, 189, 532]}]], ["block_2", ["The equations for the dissolution of aluminum hydroxide, the formation of the complex ion, and the combined\n(net) equation are shown below. As indicated by the relatively large value of K for the net reaction, coupling\ncomplex formation with dissolution drastically increases the solubility of Al(OH)3.\n"]], ["block_3", [" Increased Solubility in Acidic Solutions \n"]], ["block_4", ["Compute and compare the molar solublities for aluminum hydroxide, Al(OH)3, dissolved in (a) pure water and\n(b) a buffer containing 0.100 M acetic acid and 0.100 M sodium acetate.\n"]], ["block_5", ["Chemistry in Everyday Life\n"]], ["block_6", [" Role of Fluoride in Preventing Tooth Decay \nAs we saw previously, fluoride ions help protect our teeth by reacting with hydroxylapatite to form\nfluorapatite, Ca5(PO4)3F. Since it lacks a hydroxide ion, fluorapatite is more resistant to attacks by acids in\nour mouths and is thus less soluble, protecting our teeth. Scientists discovered that naturally fluorinated\nwater could be beneficial to your teeth, and so it became common practice to add fluoride to drinking\nwater. Toothpastes and mouthwashes also contain amounts of fluoride (Figure 15.9).\n"]], ["block_7", ["Unfortunately, excess fluoride can negate its advantages. Natural sources of drinking water in various parts\nof the world have varying concentrations of fluoride, and places where that concentration is high are prone\nto certain health risks when there is no other source of drinking water. The most serious side effect of\nexcess fluoride is the bone disease, skeletal fluorosis. When excess fluoride is in the body, it can cause the\njoints to stiffen and the bones to thicken. It can severely impact mobility and can negatively affect the\nthyroid gland. Skeletal fluorosis is a condition that over 2.7 million people suffer from across the world. So\nwhile fluoride can protect our teeth from decay, the US Environmental Protection Agency sets a maximum\nlevel of 4 ppm (4 mg/L) of fluoride in drinking water in the US. Fluoride levels in water are not regulated in\nall countries, so fluorosis is a problem in areas with high levels of fluoride in the groundwater.\n"]], ["block_8", ["EXAMPLE 15.15\n"]], ["block_9", [" FIGURE 15.9 \nFluoride, found in many toothpastes, helps prevent tooth decay (credit: Kerry Ceszyk).\n"]], ["block_10", [{"image_1": "782_1.png", "coords": [189, 168, 423, 265]}]], ["block_11", [" 15.3 \u2022 Coupled Equilibria \n 769 \n"]]], "page_783": [["block_0", [" 770 \n 15 \u2022 Equilibria of Other Reaction Classes \n"]], ["block_1", [" Solution \n"]], ["block_2", ["(a) The molar solubility of aluminum hydroxide in water is computed considering the dissolution equilibrium\nonly as demonstrated in several previous examples:\n"]], ["block_3", ["(b) The concentration of hydroxide ion of the buffered solution is conveniently calculated by the Henderson-\nHasselbalch equation:\n"]], ["block_4", ["At this pH, the concentration of hydroxide ion is\n"]], ["block_5", ["The solubility of Al(OH)3 in this buffer is then calculated from its solubility product expressions:\n"]], ["block_6", ["Compared to pure water, the solubility of aluminum hydroxide in this mildly acidic buffer is approximately ten\nmillion times greater (though still relatively low).\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["What is the solubility of aluminum hydroxide in a buffer comprised of 0.100 M formic acid and 0.100 M\nsodium formate?\n"]], ["block_9", [" Answer: \n0.1 M\n"]], ["block_10", [" Multiple Equilibria \n"]], ["block_11", ["Unexposed silver halides are removed from photographic film when they react with sodium thiosulfate\n(Na2S2O3, called hypo) to form the complex ion\n(Kf = 4.7\n10).\n"]], ["block_12", [{"image_0": "783_0.png", "coords": [72, 577, 432, 640]}]], ["block_13", ["What mass of Na2S2O3 is required to prepare 1.00 L of a solution that will dissolve 1.00 g of AgBr by the\nformation of\n"]], ["block_14", [" Solution \n"]], ["block_15", ["Two equilibria are involved when silver bromide dissolves in an aqueous thiosulfate solution containing the\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["EXAMPLE 15.16\n"]], ["block_18", ["ion:\n"]]], "page_784": [["block_0", ["dissolution:\n"]], ["block_1", ["complexation:\n"]], ["block_2", ["Combining these two equilibrium equations yields\n"]], ["block_3", ["The concentration of bromide resulting from dissolution of 1.00 g of AgBr in 1.00 L of solution is\n"]], ["block_4", ["The stoichiometry of the dissolution equilibrium indicates the same concentration of aqueous silver ion will\nresult, 0.00532 M, and the very large value of\nensures that essentially all the dissolved silver ion will be\n"]], ["block_5", ["complexed by thiosulfate ion:\n"]], ["block_6", ["Rearranging the K expression for the combined equilibrium equations and solving for the concentration of\nthiosulfate ion yields\n"]], ["block_7", ["Finally, the total mass of\nrequired to provide enough thiosulfate to yield the concentrations cited\n"]], ["block_8", ["above can be calculated.\n"]], ["block_9", ["Mass of\nrequired to yield 0.00532 M\n"]], ["block_10", ["Mass of\nrequired to yield 0.00110 M\n"]], ["block_11", ["The mass of\nrequired to dissolve 1.00 g of AgBr in 1.00 L of water is thus 1.68 g + 0.17 g = 1.85 g\n"]], ["block_12", [" Check Your Learning \n"]], ["block_13", ["AgCl(s), silver chloride, has a very low solubility:\nKsp = 1.6\n10. Adding\n"]], ["block_14", ["ammonia significantly increases the solubility of AgCl because a complex ion is formed:\n"]], ["block_15", ["solution that will dissolve 2.00 g of AgCl by formation of\n"]], ["block_16", [" Answer: \n1.00 L of a solution prepared with 4.81 g NH3 dissolves 2.0 g of AgCl.\n"]], ["block_17", ["Kf = 1.7\n10. What mass of NH3 is required to prepare 1.00 L of\n"]], ["block_18", [" 15.3 \u2022 Coupled Equilibria \n 771 \n"]]], "page_785": [["block_0", ["The equilibrium constant for an equilibrium\ninvolving the precipitation or dissolution of a slightly\nsoluble ionic solid is called the solubility product,\nKsp, of the solid. For a heterogeneous equilibrium\ninvolving the slightly soluble solid MpXq and its ions\nMand X:\n"]], ["block_1", ["The solubility product of a slightly soluble\nelectrolyte can be calculated from its solubility;\nconversely, its solubility can be calculated from its\nKsp, provided the only significant reaction that\noccurs when the solid dissolves is the formation of\nits ions.\n"]], ["block_2", [" 772 \n 15 \u2022 Key Terms \n"]], ["block_3", [" Key Terms \n"]], ["block_4", [" common ion effect \neffect on equilibrium when a\n"]], ["block_5", [" complex ion \nion consisting of a central atom\n"]], ["block_6", [" coordinate covalent bond \n(also, dative bond)\n"]], ["block_7", [" coupled equilibria \nsystem characterized the\n"]], ["block_8", [" dissociation constant \n( K d ) equilibrium constant\n"]], ["block_9", [" formation constant \n( K f ) (also, stability constant)\n"]], ["block_10", [" Key Equations \n"]], ["block_11", [" Summary \n"]], ["block_12", [" 15.1 Precipitation and Dissolution \n"]], ["block_13", ["the solubility product expression is:\n"]], ["block_14", ["A slightly soluble electrolyte begins to precipitate\nwhen the magnitude of the reaction quotient for the\ndissolution reaction exceeds the magnitude of the\nsolubility product. Precipitation continues until the\nreaction quotient equals the solubility product.\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["substance with an ion in common with the\ndissolved species is added to the solution; causes\na decrease in the solubility of an ionic species, or\na decrease in the ionization of a weak acid or base\n"]], ["block_17", ["surrounding molecules or ions called ligands via\ncoordinate covalent bonds\n"]], ["block_18", ["covalent bond in which both electrons originated\nfrom the same atom\n"]], ["block_19", ["simultaneous establishment of two or more\nequilibrium reactions sharing one or more\nreactant or product\n"]], ["block_20", ["for the decomposition of a complex ion into its\ncomponents\n"]], ["block_21", ["equilibrium constant for the formation of a\n"]], ["block_22", [" Lewis acid \nany species that can accept a pair of\n"]], ["block_23", [" Lewis acid-base adduct \ncompound or ion that\n"]], ["block_24", [" Lewis acid-base chemistry \nreactions involving the\n"]], ["block_25", [" Lewis base \nany species that can donate a pair of\n"]], ["block_26", [" ligand \nmolecule or ion acting as a Lewis base in\n"]], ["block_27", [" molar solubility \nsolubility of a compound\n"]], ["block_28", [" selective precipitation \nprocess in which ions are\n"]], ["block_29", [" solubility product constant (K sp ) \nequilibrium\n"]], ["block_30", [" 15.2 Lewis Acids and Bases \n"]], ["block_31", ["A Lewis acid is a species that can accept an electron\npair, whereas a Lewis base has an electron pair\navailable for donation to a Lewis acid. Complex ions\nare examples of Lewis acid-base adducts and\ncomprise central metal atoms or ions acting as\nLewis acids bonded to molecules or ions called\nligands that act as Lewis bases. The equilibrium\nconstant for the reaction between a metal ion and\nligands produces a complex ion called a formation\nconstant; for the reverse reaction, it is called a\ndissociation constant.\n"]], ["block_32", [" 15.3 Coupled Equilibria \n"]], ["block_33", ["Systems involving two or more chemical equilibria\nthat share one or more reactant or product are\ncalled coupled equilibria. Common examples of\ncoupled equilibria include the increased solubility of\nsome compounds in acidic solutions (coupled\ndissolution and neutralization equilibria) and in\nsolutions containing ligands (coupled dissolution\nand complex formation). The equilibrium tools from\nother chapters may be applied to describe and\nperform calculations on these systems.\n"]], ["block_34", ["complex ion from its components\n"]], ["block_35", ["electrons and form a coordinate covalent bond\n"]], ["block_36", ["contains a coordinate covalent bond between a\nLewis acid and a Lewis base\n"]], ["block_37", ["formation of coordinate covalent bonds\n"]], ["block_38", ["electrons and form a coordinate covalent bond\n"]], ["block_39", ["complex ion formation; bonds to the central atom\nof the complex\n"]], ["block_40", ["expressed in units of moles per liter (mol/L)\n"]], ["block_41", ["separated using differences in their solubility\nwith a given precipitating reagent\n"]], ["block_42", ["constant for the dissolution of an ionic compound\n"]]], "page_786": [["block_0", [" Exercises \n"]], ["block_1", [" 15.1 Precipitation and Dissolution \n"]], ["block_2", [" 1 . Complete the changes in concentrations for each of the following reactions:\n"]], ["block_3", [" 2 . Complete the changes in concentrations for each of the following reactions:\n"]], ["block_4", [" 3 . How do the concentrations of Agand\nin a saturated solution above 1.0 g of solid Ag2CrO4 change\n"]], ["block_5", [" 4 . How do the concentrations of Pband Schange when K2S is added to a saturated solution of PbS?\n"]], ["block_6", ["(a)\n"]], ["block_7", ["(b)\n"]], ["block_8", ["(c)\n"]], ["block_9", ["(d)\n"]], ["block_10", ["(e)\n"]], ["block_11", ["(a)\n"]], ["block_12", ["(b\n"]], ["block_13", ["(c)\n"]], ["block_14", ["(d)\n"]], ["block_15", ["(e)\n"]], ["block_16", ["when 100 g of solid Ag2CrO4 is added to the system? Explain.\n"]], ["block_17", [" 15 \u2022 Exercises \n 773 \n"]]], "page_787": [["block_0", [" 774 \n 15 \u2022 Exercises \n"]], ["block_1", [" 10 . The Handbook of Chemistry and Physics (http://openstax.org/l/16Handbook) gives solubilities of the\n"]], ["block_2", [" 11 . The Handbook of Chemistry and Physics (http://openstax.org/l/16Handbook) gives solubilities of the\n"]], ["block_3", [" 12 . Use solubility products and predict which of the following salts is the most soluble, in terms of moles per\n"]], ["block_4", [" 13 . Assuming that no equilibria other than dissolution are involved, calculate the molar solubility of each of\n"]], ["block_5", [" 14 . Assuming that no equilibria other than dissolution are involved, calculate the molar solubility of each of\n"]], ["block_6", [" 15 . Assuming that no equilibria other than dissolution are involved, calculate the concentration of all solute\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [" 5 . What additional information do we need to answer the following question: How is the equilibrium of solid\n"]], ["block_9", [" 6 . Which of the following slightly soluble compounds has a solubility greater than that calculated from its\n"]], ["block_10", [" 7 . Which of the following slightly soluble compounds has a solubility greater than that calculated from its\n"]], ["block_11", [" 8 . Write the ionic equation for dissolution and the solubility product (Ksp) expression for each of the following\n"]], ["block_12", [" 9 . Write the ionic equation for the dissolution and the Ksp expression for each of the following slightly soluble\n"]], ["block_13", ["silver bromide with a saturated solution of its ions affected when the temperature is raised?\n"]], ["block_14", ["solubility product because of hydrolysis of the anion present: CoSO3, CuI, PbCO3, PbCl2, Tl2S, KClO4?\n"]], ["block_15", ["solubility product because of hydrolysis of the anion present: AgCl, BaSO4, CaF2, Hg2I2, MnCO3, and ZnS?\n"]], ["block_16", ["slightly soluble ionic compounds:\n(a) PbCl2\n(b) Ag2S\n(c) Sr3(PO4)2\n(d) SrSO4\n"]], ["block_17", ["ionic compounds:\n(a) LaF3\n(b) CaCO3\n(c) Ag2SO4\n(d) Pb(OH)2\n"]], ["block_18", ["following compounds in grams per 100 mL of water. Because these compounds are only slightly soluble,\nassume that the volume does not change on dissolution and calculate the solubility product for each.\n(a) BaSiF6, 0.026 g/100 mL (contains\nions)\n"]], ["block_19", ["(b) Ce(IO3)4, 1.5\n10g/100 mL\n"]], ["block_20", ["(c) Gd2(SO4)3, 3.98 g/100 mL\n(d) (NH4)2PtBr6, 0.59 g/100 mL (contains\nions)\n"]], ["block_21", ["following compounds in grams per 100 mL of water. Because these compounds are only slightly soluble,\nassume that the volume does not change on dissolution and calculate the solubility product for each.\n(a) BaSeO4, 0.0118 g/100 mL\n(b) Ba(BrO3)2\u00b7H2O, 0.30 g/100 mL\n(c) NH4MgAsO4\u00b76H2O, 0.038 g/100 mL\n(d) La2(MoO4)3, 0.00179 g/100 mL\n"]], ["block_22", ["liter, in pure water: CaF2, Hg2Cl2, PbI2, or Sn(OH)2.\n"]], ["block_23", ["the following from its solubility product:\n(a) KHC4H4O6\n(b) PbI2\n(c) Ag4[Fe(CN)6], a salt containing the\nion\n"]], ["block_24", ["(d) Hg2I2\n"]], ["block_25", ["the following from its solubility product:\n(a) Ag2SO4\n(b) PbBr2\n(c) AgI\n(d) CaC2O4\u00b7H2O\n"]], ["block_26", ["species in each of the following solutions of salts in contact with a solution containing a common ion.\nShow that changes in the initial concentrations of the common ions can be neglected.\n(a) AgCl(s) in 0.025 M NaCl\n(b) CaF2(s) in 0.00133 M KF\n(c) Ag2SO4(s) in 0.500 L of a solution containing 19.50 g of K2SO4\n(d) Zn(OH)2(s) in a solution buffered at a pH of 11.45\n"]]], "page_788": [["block_0", [" 16 . Assuming that no equilibria other than dissolution are involved, calculate the concentration of all solute\n"]], ["block_1", [" 17 . Assuming that no equilibria other than dissolution are involved, calculate the concentration of all solute\n"]], ["block_2", [" 18 . Explain why the changes in concentrations of the common ions in Exercise 15.17 can be neglected.\n 19 . Explain why the changes in concentrations of the common ions in Exercise 15.18 cannot be neglected.\n 20 . Calculate the solubility of aluminum hydroxide, Al(OH)3, in a solution buffered at pH 11.00.\n 21 . Refer to Appendix J for solubility products for calcium salts. Determine which of the calcium salts listed is\n"]], ["block_3", [" 22 . Most barium compounds are very poisonous; however, barium sulfate is often administered internally as\n"]], ["block_4", [" 23 . Public Health Service standards for drinking water set a maximum of 250 mg/L (2.60\n10M) of\n"]], ["block_5", [" 24 . Perform the following calculations:\n"]], ["block_6", [" 25 . The solubility product of CaSO4\u00b72H2O is 2.4\n10. What mass of this salt will dissolve in 1.0 L of 0.010 M\n"]], ["block_7", [" 26 . Assuming that no equilibria other than dissolution are involved, calculate the concentrations of ions in a\n"]], ["block_8", [" 27 . Assuming that no equilibria other than dissolution are involved, calculate the concentrations of ions in a\n"]], ["block_9", ["species in each of the following solutions of salts in contact with a solution containing a common ion.\nShow that changes in the initial concentrations of the common ions can be neglected.\n(a) TlCl(s) in 1.250 M HCl\n(b) PbI2(s) in 0.0355 M CaI2\n(c) Ag2CrO4(s) in 0.225 L of a solution containing 0.856 g of K2CrO4\n(d) Cd(OH)2(s) in a solution buffered at a pH of 10.995\n"]], ["block_10", ["species in each of the following solutions of salts in contact with a solution containing a common ion.\nShow that it is not appropriate to neglect the changes in the initial concentrations of the common ions.\n(a) TlCl(s) in 0.025 M TlNO3\n(b) BaF2(s) in 0.0313 M KF\n(c) MgC2O4 in 2.250 L of a solution containing 8.156 g of Mg(NO3)2\n(d) Ca(OH)2(s) in an unbuffered solution initially with a pH of 12.700\n"]], ["block_11", ["most soluble in moles per liter and which is most soluble in grams per liter.\n"]], ["block_12", ["an aid in the X-ray examination of the lower intestinal tract (Figure 15.4). This use of BaSO4 is possible\nbecause of its low solubility. Calculate the molar solubility of BaSO4 and the mass of barium present in\n1.00 L of water saturated with BaSO4.\n"]], ["block_13", ["because of its cathartic action (it is a laxative). Does natural water that is saturated with CaSO4 (\u201cgyp\u201d\nwater) as a result or passing through soil containing gypsum, CaSO4\u00b72H2O, meet these standards? What is\nthe concentration of\nin such water?\n"]], ["block_14", ["(a) Calculate [Ag] in a saturated aqueous solution of AgBr.\n(b) What will [Ag] be when enough KBr has been added to make [Br] = 0.050 M?\n(c) What will [Br] be when enough AgNO3 has been added to make [Ag] = 0.020 M?\n"]], ["block_15", ["saturated solution of each of the following (see Appendix J for solubility products).\n(a) TlCl\n(b) BaF2\n(c) Ag2CrO4\n(d) CaC2O4\u00b7H2O\n(e) the mineral anglesite, PbSO4\n"]], ["block_16", ["saturated solution of each of the following (see Appendix J for solubility products):\n(a) AgI\n(b) Ag2SO4\n(c) Mn(OH)2\n(d) Sr(OH)2\u00b78H2O\n(e) the mineral brucite, Mg(OH)2\n"]], ["block_17", [" 15 \u2022 Exercises \n 775 \n"]]], "page_789": [["block_0", [" 776 \n 15 \u2022 Exercises \n"]], ["block_1", [" 28 . The following concentrations are found in mixtures of ions in equilibrium with slightly soluble solids.\n"]], ["block_2", [" 29 . The following concentrations are found in mixtures of ions in equilibrium with slightly soluble solids.\n"]], ["block_3", [" 30 . Which of the following compounds precipitates from a solution that has the concentrations indicated?\n"]], ["block_4", [" 31 . Which of the following compounds precipitates from a solution that has the concentrations indicated?\n"]], ["block_5", [" 32 . Calculate the concentration of Tlwhen TlCl just begins to precipitate from a solution that is 0.0250 M in\n"]], ["block_6", [" 33 . Calculate the concentration of sulfate ion when BaSO4 just begins to precipitate from a solution that is\n"]], ["block_7", [" 34 . Calculate the concentration of Srwhen SrCrO4 starts to precipitate from a solution that is 0.0025 M in\n"]], ["block_8", [" 35 . Calculate the concentration of\nwhen Ag3PO4 starts to precipitate from a solution that is 0.0125 M in\n"]], ["block_9", [" 36 . Calculate the concentration of Frequired to begin precipitation of CaF2 in a solution that is 0.010 M in\n"]], ["block_10", [" 37 . Calculate the concentration of Agrequired to begin precipitation of Ag2CO3 in a solution that is 2.50\n"]], ["block_11", [" 38 . What [Ag] is required to reduce\nto 8.2\n10M by precipitation of Ag2CO3?\n"]], ["block_12", [" 39 . What [F] is required to reduce [Ca] to 1.0\n10M by precipitation of CaF2?\n"]], ["block_13", [" 40 . A volume of 0.800 L of a 2\n10-M Ba(NO3)2 solution is added to 0.200 L of 5\n10M Li2SO4. Does\n"]], ["block_14", [" 41 . Perform these calculations for nickel(II) carbonate. (a) With what volume of water must a precipitate\n"]], ["block_15", [" 42 . Iron concentrations greater than 5.4\n10M in water used for laundry purposes can cause staining.\n"]], ["block_16", [" 43 . A solution is 0.010 M in both Cuand Cd. What percentage of Cdremains in the solution when 99.9%\n"]], ["block_17", [" 44 . A solution is 0.15 M in both Pband Ag. If Clis added to this solution, what is [Ag] when PbCl2 begins to\n"]], ["block_18", [" Access for free at openstax.org \n"]], ["block_19", ["From the concentrations given, calculate Ksp for each of the slightly soluble solids indicated:\n(a) AgBr: [Ag] = 5.7\n10M, [Br] = 5.7\n10M\n"]], ["block_20", ["(b) CaCO3: [Ca] = 5.3\n10M,\n= 9.0\n10M\n"]], ["block_21", ["(c) PbF2: [Pb] = 2.1\n10M, [F] = 4.2\n10M\n"]], ["block_22", ["(d) Ag2CrO4: [Ag] = 5.3\n10M, 3.2\n10M\n"]], ["block_23", ["(e) InF3: [In] = 2.3\n10M, [F] = 7.0\n10M\n"]], ["block_24", ["From the concentrations given, calculate Ksp for each of the slightly soluble solids indicated:\n(a) TlCl: [Tl] = 1.21\n10M, [Cl] = 1.2\n10M\n"]], ["block_25", ["(b) Ce(IO3)4: [Ce] = 1.8\n10M,\n= 2.6\n10M\n"]], ["block_26", ["(c) Gd2(SO4)3: [Gd] = 0.132 M,\n= 0.198 M\n"]], ["block_27", ["(d) Ag2SO4: [Ag] = 2.40\n10M,\n= 2.05\n10M\n"]], ["block_28", ["(e) BaSO4: [Ba] = 0.500 M,\n= 4.6\n10M\n"]], ["block_29", ["(See Appendix J for Ksp values.)\n(a) KClO4: [K] = 0.01 M,\n= 0.01 M\n"]], ["block_30", ["(b) K2PtCl6: [K] = 0.01 M,\n= 0.01 M\n"]], ["block_31", ["(c) PbI2: [Pb] = 0.003 M, [I] = 1.3\n10M\n"]], ["block_32", ["(d) Ag2S: [Ag] = 1\n10M, [S] = 1\n10M\n"]], ["block_33", ["(See Appendix J for Ksp values.)\n(a) CaCO3: [Ca] = 0.003 M,\n= 0.003 M\n"]], ["block_34", ["(b) Co(OH)2: [Co] = 0.01 M, [OH] = 1\n10M\n"]], ["block_35", ["(c) CaHPO4: [Ca] = 0.01 M,\n= 2\n10M\n"]], ["block_36", ["(d) Pb3(PO4)2: [Pb] = 0.01 M,\n= 1\n10M\n"]], ["block_37", ["Cl.\n"]], ["block_38", ["0.0758 M in Ba.\n"]], ["block_39", ["CrO4.\n"]], ["block_40", ["Ag.\n"]], ["block_41", ["Ca.\n"]], ["block_42", ["10M in\n"]], ["block_43", ["BaSO4 precipitate? Explain your answer.\n"]], ["block_44", ["containing NiCO3 be washed to dissolve 0.100 g of this compound? Assume that the wash water becomes\nsaturated with NiCO3 (Ksp = 1.36\n10).\n"]], ["block_45", ["(b) If the NiCO3 were a contaminant in a sample of CoCO3 (Ksp = 1.0\n10), what mass of CoCO3 would\n"]], ["block_46", ["have been lost? Keep in mind that both NiCO3 and CoCO3 dissolve in the same solution.\n"]], ["block_47", ["What [OH] is required to reduce [Fe] to this level by precipitation of Fe(OH)2?\n"]], ["block_48", ["of the Cuhas been precipitated as CuS by adding sulfide?\n"]], ["block_49", ["precipitate?\n"]]], "page_790": [["block_0", [" 45 . What reagent might be used to separate the ions in each of the following mixtures, which are 0.1 M with\n"]], ["block_1", [" 46 . A solution contains 1.0\n10mol of KBr and 0.10 mol of KCl per liter. AgNO3 is gradually added to this\n"]], ["block_2", [" 47 . A solution contains 1.0\n10mol of KI and 0.10 mol of KCl per liter. AgNO3 is gradually added to this\n"]], ["block_3", [" 48 . The calcium ions in human blood serum are necessary for coagulation (Figure 15.5). Potassium oxalate,\n"]], ["block_4", [" 49 . About 50% of urinary calculi (kidney stones) consist of calcium phosphate, Ca3(PO4)2. The normal mid\n"]], ["block_5", [" 50 . The pH of normal urine is 6.30, and the total phosphate concentration\n+\n+\n"]], ["block_6", [" 51 . Magnesium metal (a component of alloys used in aircraft and a reducing agent used in the production of\n"]], ["block_7", [" 52 . Hydrogen sulfide is bubbled into a solution that is 0.10 M in both Pband Feand 0.30 M in HCl. After\n"]], ["block_8", [" 53 . Perform the following calculations involving concentrations of iodate ions:\n"]], ["block_9", [" 54 . Calculate the molar solubility of AgBr in 0.035 M NaBr (Ksp = 5\n10).\n"]], ["block_10", [" 55 . How many grams of Pb(OH)2 will dissolve in 500 mL of a 0.050-M PbCl2 solution (Ksp = 1.2\n10)?\n"]], ["block_11", [" 56 . Use the simulation (http://openstax.org/l/16solublesalts) from the earlier Link to Learning to complete the\n"]], ["block_12", ["respect to each ion? In some cases it may be necessary to control the pH. (Hint: Consider the Ksp values\ngiven in Appendix J.)\n(a)\nand Cu\n"]], ["block_13", ["(b)\nand Cl\n"]], ["block_14", ["(c) Hgand Co\n"]], ["block_15", ["(d) Znand Sr\n"]], ["block_16", ["(e) Baand Mg\n"]], ["block_17", ["(f)\nand OH\n"]], ["block_18", ["solution. Which forms first, solid AgBr or solid AgCl?\n"]], ["block_19", ["solution. Which forms first, solid AgI or solid AgCl?\n"]], ["block_20", ["K2C2O4, is used as an anticoagulant when a blood sample is drawn for laboratory tests because it removes\nthe calcium as a precipitate of CaC2O4\u00b7H2O. It is necessary to remove all but 1.0% of the Cain serum in\norder to prevent coagulation. If normal blood serum with a buffered pH of 7.40 contains 9.5 mg of Caper\n100 mL of serum, what mass of K2C2O4 is required to prevent the coagulation of a 10 mL blood sample\nthat is 55% serum by volume? (All volumes are accurate to two significant figures. Note that the volume of\nserum in a 10-mL blood sample is 5.5 mL. Assume that the Ksp value for CaC2O4 in serum is the same as in\nwater.)\n"]], ["block_21", ["range calcium content excreted in the urine is 0.10 g of Caper day. The normal mid range amount of\nurine passed may be taken as 1.4 L per day. What is the maximum concentration of phosphate ion that\nurine can contain before a calculus begins to form?\n"]], ["block_22", ["+ [H3PO4]) is 0.020 M. What is the minimum concentration of Canecessary to induce kidney stone\nformation? (See Exercise 15.49 for additional information.)\n"]], ["block_23", ["uranium, titanium, and other active metals) is isolated from sea water by the following sequence of\nreactions:\n"]], ["block_24", ["Sea water has a density of 1.026 g/cmand contains 1272 parts per million of magnesium as Mg(aq) by\nmass. What mass, in kilograms, of Ca(OH)2 is required to precipitate 99.9% of the magnesium in 1.00\n10L of sea water?\n"]], ["block_25", ["the solution has come to equilibrium it is saturated with H2S ([H2S] = 0.10 M). What concentrations of Pb\n"]], ["block_26", ["and Feremain in the solution? For a saturated solution of H2S we can use the equilibrium:\n"]], ["block_27", ["(Hint: The\nchanges as metal sulfides precipitate.)\n"]], ["block_28", ["(a) The iodate ion concentration of a saturated solution of La(IO3)3 was found to be 3.1\n10mol/L. Find\n"]], ["block_29", ["the Ksp.\n(b) Find the concentration of iodate ions in a saturated solution of Cu(IO3)2 (Ksp = 7.4\n10).\n"]], ["block_30", ["following exercise. Using 0.01 g CaF2, give the Ksp values found in a 0.2-M solution of each of the salts.\nDiscuss why the values change as you change soluble salts.\n"]], ["block_31", [" 15 \u2022 Exercises \n 777 \n"]]], "page_791": [["block_0", [" 778 \n 15 \u2022 Exercises \n"]], ["block_1", [" 57 . How many grams of Milk of Magnesia, Mg(OH)2 (s) (58.3 g/mol), would be soluble in 200 mL of water. Ksp =\n"]], ["block_2", [" 58 . Two hypothetical salts, LM2 and LQ, have the same molar solubility in H2O. If Ksp for LM2 is 3.20\n10,\n"]], ["block_3", [" 59 . The carbonate ion concentration is gradually increased in a solution containing equal concentrations of\n"]], ["block_4", [" 60 . How many grams of Zn(CN)2(s) (117.44 g/mol) would be soluble in 100 mL of H2O? Include the balanced\n"]], ["block_5", [" 15.2 Lewis Acids and Bases \n"]], ["block_6", [" 61 . Even though Ca(OH)2 is an inexpensive base, its limited solubility restricts its use. What is the pH of a\n"]], ["block_7", [" 62 . Under what circumstances, if any, does a sample of solid AgCl completely dissolve in pure water?\n 63 . Explain why the addition of NH3 or HNO3 to a saturated solution of Ag2CO3 in contact with solid Ag2CO3\n"]], ["block_8", [" 64 . Calculate the cadmium ion concentration, [Cd], in a solution prepared by mixing 0.100 L of 0.0100 M\n"]], ["block_9", [" 65 . Explain why addition of NH3 or HNO3 to a saturated solution of Cu(OH)2 in contact with solid Cu(OH)2\n"]], ["block_10", [" 66 . Sometimes equilibria for complex ions are described in terms of dissociation constants, Kd. For the\n"]], ["block_11", [" 67 . Using the value of the formation constant for the complex ion\ncalculate the dissociation\n"]], ["block_12", [" 68 . Using the dissociation constant, Kd = 7.8\n10, calculate the equilibrium concentrations of Cdand\n"]], ["block_13", [" 69 . Using the dissociation constant, Kd = 3.4\n10, calculate the equilibrium concentrations of Znand\n"]], ["block_14", [" 70 . Using the dissociation constant, Kd = 2.2\n10, calculate the equilibrium concentrations of Coand\n"]], ["block_15", [" 71 . Using the dissociation constant, Kd = 1\n10, calculate the equilibrium concentrations of Feand CN\n"]], ["block_16", [" 72 . Calculate the mass of potassium cyanide ion that must be added to 100 mL of solution to dissolve 2.0\n"]], ["block_17", [" 73 . Calculate the minimum concentration of ammonia needed in 1.0 L of solution to dissolve 3.0\n10mol of\n"]], ["block_18", [" 74 . A roll of 35-mm black and white photographic film contains about 0.27 g of unexposed AgBr before\n"]], ["block_19", [" Access for free at openstax.org \n"]], ["block_20", ["7.1\n10. Include the ionic reaction and the expression for Ksp in your answer. (Kw = 1\n10=\n"]], ["block_21", ["[H3O][OH])\n"]], ["block_22", ["what is the Ksp value for LQ?\n"]], ["block_23", ["the divalent cations of magnesium, calcium, strontium, barium, and manganese. Which of the following\ncarbonates will precipitate first? Which will precipitate last? Explain.\n(a)\n"]], ["block_24", ["(b)\n"]], ["block_25", ["(c)\n"]], ["block_26", ["(d)\n"]], ["block_27", ["(e)\n"]], ["block_28", ["reaction and the expression for Ksp in your answer. The Ksp value for Zn(CN)2(s) is 3.0\n10.\n"]], ["block_29", ["saturated solution of Ca(OH)2?\n"]], ["block_30", ["increases the solubility of the solid.\n"]], ["block_31", ["Cd(NO3)2 with 0.150 L of 0.100 NH3(aq).\n"]], ["block_32", ["increases the solubility of the solid.\n"]], ["block_33", ["complex ion\nthe dissociation reaction is:\n"]], ["block_34", ["Calculate the value of the formation constant, Kf, for\n"]], ["block_35", ["constant.\n"]], ["block_36", ["CNin a 0.250-M solution of\n"]], ["block_37", ["OHin a 0.0465-M solution of\n"]], ["block_38", ["NH3 in a 0.500-M solution of\n"]], ["block_39", ["in a 0.333 M solution of\n"]], ["block_40", ["10mol of silver cyanide, AgCN.\n"]], ["block_41", ["silver bromide.\n"]], ["block_42", ["developing. What mass of Na2S2O3\u00b75H2O (sodium thiosulfate pentahydrate or hypo) in 1.0 L of developer\nis required to dissolve the AgBr as\n(Kf = 4.7\n10)?\n"]], ["block_43", ["and\n"]]], "page_792": [["block_0", [" 75 . We have seen an introductory definition of an acid: An acid is a compound that reacts with water and\n"]], ["block_1", [" 76 . Write the Lewis structures of the reactants and product of each of the following equations, and identify the\n"]], ["block_2", [" 77 . Write the Lewis structures of the reactants and product of each of the following equations, and identify the\n"]], ["block_3", [" 78 . Using Lewis structures, write balanced equations for the following reactions:\n"]], ["block_4", [" 79 . Calculate\nin a solution prepared by adding 0.0200 mol of NaCl to 0.250 L of a 0.100-M HgCl2\n"]], ["block_5", [" 80 . In a titration of cyanide ion, 28.72 mL of 0.0100 M AgNO3 is added before precipitation begins. [The\n"]], ["block_6", [" 81 . What are the concentrations of Ag, CN, and\nin a saturated solution of AgCN?\n"]], ["block_7", [" 82 . In dilute aqueous solution HF acts as a weak acid. However, pure liquid HF (boiling point = 19.5 \u00b0C) is a\n"]], ["block_8", [" 83 . The simplest amino acid is glycine, H2NCH2CO2H. The common feature of amino acids is that they contain\n"]], ["block_9", [" 84 . Boric acid, H3BO3, is not a Br\u00f8nsted-Lowry acid but a Lewis acid.\n"]], ["block_10", ["increases the amount of hydronium ion present. In the chapter on acids and bases, we saw two more\ndefinitions of acids: a compound that donates a proton (a hydrogen ion, H) to another compound is called\na Br\u00f8nsted-Lowry acid, and a Lewis acid is any species that can accept a pair of electrons. Explain why the\nintroductory definition is a macroscopic definition, while the Br\u00f8nsted-Lowry definition and the Lewis\ndefinition are microscopic definitions.\n"]], ["block_11", ["Lewis acid and the Lewis base in each:\n(a)\n(b)\n(c)\n(d)\n(use Al-Cl single bonds)\n"]], ["block_12", ["(e)\n"]], ["block_13", ["Lewis acid and the Lewis base in each:\n(a)\n(b)\n(c)\n(d)\n(e)\n"]], ["block_14", ["(a)\n(b)\n(c)\n(d)\n"]], ["block_15", ["solution.\n"]], ["block_16", ["reaction of Agwith CNgoes to completion, producing the\ncomplex.] Precipitation of solid\n"]], ["block_17", ["AgCN takes place when excess Agis added to the solution, above the amount needed to complete the\nformation of\nHow many grams of NaCN were in the original sample?\n"]], ["block_18", ["strong acid. In liquid HF, HNO3 acts like a base and accepts protons. The acidity of liquid HF can be\nincreased by adding one of several inorganic fluorides that are Lewis acids and accept Fion (for example,\nBF3 or SbF5). Write balanced chemical equations for the reaction of pure HNO3 with pure HF and of pure\nHF with BF3.\n"]], ["block_19", ["the functional groups: an amine group, \u2013NH2, and a carboxylic acid group, \u2013CO2H. An amino acid can\nfunction as either an acid or a base. For glycine, the acid strength of the carboxyl group is about the same\nas that of acetic acid, CH3CO2H, and the base strength of the amino group is slightly greater than that of\nammonia, NH3.\n(a) Write the Lewis structures of the ions that form when glycine is dissolved in 1 M HCl and in 1 M KOH.\n(b) Write the Lewis structure of glycine when this amino acid is dissolved in water. (Hint: Consider the\nrelative base strengths of the \u2013NH2 and\ngroups.)\n"]], ["block_20", ["(a) Write an equation for its reaction with water.\n(b) Predict the shape of the anion thus formed.\n(c) What is the hybridization on the boron consistent with the shape you have predicted?\n"]], ["block_21", [" 15 \u2022 Exercises \n 779 \n"]]], "page_793": [["block_0", [" 780 \n 15 \u2022 Exercises \n"]], ["block_1", [" 15.3 Coupled Equilibria \n"]], ["block_2", [" 85 . A saturated solution of a slightly soluble electrolyte in contact with some of the solid electrolyte is said to\n"]], ["block_3", [" 86 . Calculate the equilibrium concentration of Niin a 1.0-M solution [Ni(NH3)6](NO3)2.\n 87 . Calculate the equilibrium concentration of Znin a 0.30-M solution of\n 88 . Calculate the equilibrium concentration of Cuin a solution initially with 0.050 M Cuand 1.00 M NH3.\n 89 . Calculate the equilibrium concentration of Znin a solution initially with 0.150 M Znand 2.50 M CN.\n 90 . Calculate the Feequilibrium concentration when 0.0888 mole of K3[Fe(CN)6] is added to a solution with\n"]], ["block_4", [" 91 . Calculate the Coequilibrium concentration when 0.010 mole of [Co(NH3)6](NO3)2 is added to a solution\n"]], ["block_5", [" 92 . Calculate the molar solubility of Sn(OH)2 in a buffer solution containing equal concentrations of NH3 and\n"]], ["block_6", [" 93 . Calculate the molar solubility of Al(OH)3 in a buffer solution with 0.100 M NH3 and 0.400 M\n 94 . What is the molar solubility of CaF2 in a 0.100-M solution of HF? Ka for HF = 6.4\n10.\n"]], ["block_7", [" 95 . What is the molar solubility of BaSO4 in a 0.250-M solution of NaHSO4? Ka for\n= 1.2\n10.\n"]], ["block_8", [" 96 . What is the molar solubility of Tl(OH)3 in a 0.10-M solution of NH3?\n 97 . What is the molar solubility of Pb(OH)2 in a 0.138-M solution of CH3NH2?\n 98 . A solution of 0.075 M CoBr2 is saturated with H2S ([H2S] = 0.10 M). What is the minimum pH at which CoS\n"]], ["block_9", [" 99 . A 0.125-M solution of Mn(NO3)2 is saturated with H2S ([H2S] = 0.10 M). At what pH does MnS begin to\n"]], ["block_10", [" 100 . Both AgCl and AgI dissolve in NH3.\n"]], ["block_11", [" 101 . The following question is taken from a Chemistry Advanced Placement Examination and is used with the\n"]], ["block_12", [" 102 . Which of the following compounds, when dissolved in a 0.01-M solution of HClO4, has a solubility greater\n"]], ["block_13", [" 103 . Which of the following compounds, when dissolved in a 0.01-M solution of HClO4, has a solubility greater\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["be a system in equilibrium. Explain. Why is such a system called a heterogeneous equilibrium?\n"]], ["block_16", ["0.0.00010 M CN.\n"]], ["block_17", ["with 0.25 M NH3. Assume the volume is 1.00 L.\n"]], ["block_18", ["begins to precipitate?\n"]], ["block_19", ["precipitate?\n"]], ["block_20", ["(a) What mass of AgI dissolves in 1.0 L of 1.0 M NH3?\n(b) What mass of AgCl dissolves in 1.0 L of 1.0 M NH3?\n"]], ["block_21", ["permission of the Educational Testing Service.\nSolve the following problem:\n"]], ["block_22", ["In a saturated solution of MgF2 at 18 \u00b0C, the concentration of Mgis 1.21\n10M. The equilibrium is\n"]], ["block_23", ["represented by the preceding equation.\n(a) Write the expression for the solubility-product constant, Ksp, and calculate its value at 18 \u00b0C.\n(b) Calculate the equilibrium concentration of Mgin 1.000 L of saturated MgF2 solution at 18 \u00b0C to\nwhich 0.100 mol of solid KF has been added. The KF dissolves completely. Assume the volume change is\nnegligible.\n(c) Predict whether a precipitate of MgF2 will form when 100.0 mL of a 3.00\n10-M solution of\n"]], ["block_24", ["Mg(NO3)2 is mixed with 200.0 mL of a 2.00\n10-M solution of NaF at 18 \u00b0C. Show the calculations to\n"]], ["block_25", ["support your prediction.\n(d) At 27 \u00b0C the concentration of Mgin a saturated solution of MgF2 is 1.17\n10M. Is the dissolving of\n"]], ["block_26", ["MgF2 in water an endothermic or an exothermic process? Give an explanation to support your\nconclusion.\n"]], ["block_27", ["than in pure water: CuCl, CaCO3, MnS, PbBr2, CaF2? Explain your answer.\n"]], ["block_28", ["than in pure water: AgBr, BaF2, Ca3(PO4)2, ZnS, PbI2? Explain your answer.\n"]]], "page_794": [["block_0", [" 104 . What is the effect on the amount of solid Mg(OH)2 that dissolves and the concentrations of Mgand OH\n"]], ["block_1", [" 105 . What is the effect on the amount of CaHPO4 that dissolves and the concentrations of Caand\n"]], ["block_2", [" 106 . Identify all chemical species present in an aqueous solution of Ca3(PO4)2 and list these species in\n"]], ["block_3", ["when each of the following are added to a mixture of solid Mg(OH)2 and water at equilibrium?\n(a) MgCl2\n(b) KOH\n(c) HClO4\n(d) NaNO3\n(e) Mg(OH)2\n"]], ["block_4", ["when each of the following are added to a mixture of solid CaHPO4 and water at equilibrium?\n(a) CaCl2\n(b) HCl\n(c) KClO4\n(d) NaOH\n(e) CaHPO4\n"]], ["block_5", ["decreasing order of their concentrations. (Hint: Remember that the\nion is a weak base.)\n"]], ["block_6", [" 15 \u2022 Exercises \n 781 \n"]]], "page_795": [["block_0", [" 782 \n 15 \u2022 Exercises \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_796": [["block_0", ["CHAPTER 16\nThermodynamics\n"]], ["block_1", [{"image_0": "796_0.png", "coords": [72, 104, 622, 358]}]], ["block_2", [" Figure 16.1 \nGeysers are a dramatic display of thermodynamic principles in nature. Water deep within the\n"]], ["block_3", ["underground channels of the geyser is under high pressure and heated to high temperature by magma. When a\npocket of water near the surface reaches boiling point and is expelled, the resulting drop in pressure causes larger\nvolumes of water to flash boil, forcefully ejecting steam and water in an impressive eruption. (credit: modification of\nwork by Yellowstone National Park)\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 16.1 Spontaneity \n 16.2 Entropy \n"]], ["block_6", [" 16.3 The Second and Third Laws of Thermodynamics \n 16.4 Free Energy \n"]], ["block_7", [" INTRODUCTION \n"]], ["block_8", ["under specified conditions. Thermodynamics, the study of relationships between the energy and work\nassociated with chemical and physical processes, provides this predictive ability. Previous chapters in this text\nhave described various applications of thermochemistry, an important aspect of thermodynamics concerned\nwith the heat flow accompanying chemical reactions and phase transitions. This chapter will introduce\nadditional thermodynamic concepts, including those that enable the prediction of any chemical or physical\nchanges under a given set of conditions.\n"]], ["block_9", [" 16.1 Spontaneity \n"]], ["block_10", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_11", ["\u2022\nDistinguish between spontaneous and nonspontaneous processes\n"]], ["block_12", ["\u2022\nDescribe the dispersal of matter and energy that accompanies certain spontaneous processes\n"]], ["block_13", ["Among the many capabilities of chemistry is its ability to predict if a process will occur\n"]]], "page_797": [["block_0", [" 784 \n 16 \u2022 Thermodynamics \n"]], ["block_1", ["The phase diagram for carbon indicates that graphite is the stable form of this element under ambient\natmospheric pressure, while diamond is the stable allotrope at very high pressures, such as those present\nduring its geologic formation. Thermodynamic calculations of the sort described in the last section of this\nchapter indicate that the conversion of diamond to graphite at ambient pressure occurs spontaneously, yet\ndiamonds are observed to exist, and persist, under these conditions. Though the process is spontaneous under\ntypical ambient conditions, its rate is extremely slow; so, for all practical purposes diamonds are indeed\n\u201cforever.\u201d Situations such as these emphasize the important distinction between the thermodynamic and the\nkinetic aspects of a process. In this particular case, diamonds are said to be thermodynamically unstable but\nkinetically stable under ambient conditions.\n"]], ["block_2", ["Processes have a natural tendency to occur in one direction under a given set of conditions. Water will\nnaturally flow downhill, but uphill flow requires outside intervention such as the use of a pump. Iron exposed\nto the earth\u2019s atmosphere will corrode, but rust is not converted to iron without intentional chemical\ntreatment. A spontaneous process is one that occurs naturally under certain conditions. A nonspontaneous \n process , on the other hand, will not take place unless it is \u201cdriven\u201d by the continual input of energy from an\nexternal source. A process that is spontaneous in one direction under a particular set of conditions is\nnonspontaneous in the reverse direction. At room temperature and typical atmospheric pressure, for example,\nice will spontaneously melt, but water will not spontaneously freeze.\n"]], ["block_3", ["The spontaneity of a process is not correlated to the speed of the process. A spontaneous change may be so\nrapid that it is essentially instantaneous or so slow that it cannot be observed over any practical period of time.\nTo illustrate this concept, consider the decay of radioactive isotopes, a topic more thoroughly treated in the\nchapter on nuclear chemistry. Radioactive decay is by definition a spontaneous process in which the nuclei of\nunstable isotopes emit radiation as they are converted to more stable nuclei. All the decay processes occur\nspontaneously, but the rates at which different isotopes decay vary widely. Technetium-99m is a popular\nradioisotope for medical imaging studies that undergoes relatively rapid decay and exhibits a half-life of about\nsix hours. Uranium-238 is the most abundant isotope of uranium, and its decay occurs much more slowly,\nexhibiting a half-life of more than four billion years (Figure 16.2).\n"]], ["block_4", [" FIGURE 16.2 \nBoth U-238 and Tc-99m undergo spontaneous radioactive decay, but at drastically different rates.\n"]], ["block_5", ["Over the course of one week, essentially all of a Tc-99m sample and none of a U-238 sample will have decayed.\n"]], ["block_6", ["As another example, consider the conversion of diamond into graphite (Figure 16.3).\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [{"image_0": "797_0.png", "coords": [189, 284, 423, 489]}]]], "page_798": [["block_0", ["ambient pressure, but its rate is immeasurably slow at low to moderate temperatures. This process is known as\ngraphitization, and its rate can be increased to easily measurable values at temperatures in the 1000\u20132000 K range.\n(credit \"diamond\" photo: modification of work by \"Fancy Diamonds\"/Flickr; credit \"graphite\" photo: modification of\nwork by images-of-elements.com/carbon.php)\n"]], ["block_1", ["Note as well that since the system is isolated, no heat has been exchanged with the surroundings (q = 0). The\nfirst law of thermodynamics confirms that there has been no change in the system\u2019s internal energy as a result\nof this process.\n"]], ["block_2", [" FIGURE 16.3 \nThe conversion of carbon from the diamond allotrope to the graphite allotrope is spontaneous at\n"]], ["block_3", [" Dispersal of Matter and Energy \n"]], ["block_4", ["Extending the discussion of thermodynamic concepts toward the objective of predicting spontaneity, consider\nnow an isolated system consisting of two flasks connected with a closed valve. Initially there is an ideal gas in\none flask and the other flask is empty (P = 0). (Figure 16.4). When the valve is opened, the gas spontaneously\nexpands to fill both flasks equally. Recalling the definition of pressure-volume work from the chapter on\nthermochemistry, note that no work has been done because the pressure in a vacuum is zero.\n"]], ["block_5", ["The spontaneity of this process is therefore not a consequence of any change in energy that accompanies the\nprocess. Instead, the driving force appears to be related to the greater, more uniform dispersal of matter that\nresults when the gas is allowed to expand. Initially, the system was comprised of one flask containing matter\nand another flask containing nothing. After the spontaneous expansion took place, the matter was distributed\nboth more widely (occupying twice its original volume) and more uniformly (present in equal amounts in each\nflask).\n"]], ["block_6", [{"image_0": "798_0.png", "coords": [72, 614, 540, 707]}]], ["block_7", [" FIGURE 16.4 \nAn isolated system consists of an ideal gas in one flask that is connected by a closed valve to a\n"]], ["block_8", [{"image_1": "798_1.png", "coords": [130, 57, 481, 293]}]], ["block_9", [" 16.1 \u2022 Spontaneity \n 785 \n"]]], "page_799": [["block_0", [" 786 \n 16 \u2022 Thermodynamics \n"]], ["block_1", ["From the perspective of this two-object system, there was no net gain or loss of thermal energy, rather the\navailable thermal energy was redistributed among the two objects. This spontaneous process resulted in a\nmore uniform dispersal of energy.\n"]], ["block_2", ["second flask containing a vacuum. Once the valve is opened, the gas spontaneously becomes evenly distributed\nbetween the flasks.\n"]], ["block_3", ["Now consider two objects at different temperatures: object X at temperature TX and object Y at temperature TY,\nwith TX > TY (Figure 16.5). When these objects come into contact, heat spontaneously flows from the hotter\nobject (X) to the colder one (Y). This corresponds to a loss of thermal energy by X and a gain of thermal energy\nby Y.\n"]], ["block_4", [" FIGURE 16.5 \nWhen two objects at different temperatures come in contact, heat spontaneously flows from the\n"]], ["block_5", ["hotter to the colder object.\n"]], ["block_6", ["As illustrated by the two processes described, an important factor in determining the spontaneity of a process\nis the extent to which it changes the dispersal or distribution of matter and/or energy. In each case, a\nspontaneous process took place that resulted in a more uniform distribution of matter or energy.\n"]], ["block_7", [" Redistribution of Matter during a Spontaneous Process \n"]], ["block_8", ["Describe how matter is redistributed when the following spontaneous processes take place:\n"]], ["block_9", ["(a) A solid sublimes.\n"]], ["block_10", ["(b) A gas condenses.\n"]], ["block_11", ["(c) A drop of food coloring added to a glass of water forms a solution with uniform color.\n"]], ["block_12", [" Solution \n"]], ["block_13", [" FIGURE 16.6 \n(credit a: modification of work by Jenny Downing; credit b: modification of work by \u201cFuzzy\n"]], ["block_14", ["Gerdes\u201d/Flickr; credit c: modification of work by Paul A. Flowers)\n"]], ["block_15", ["(a) Sublimation is the conversion of a solid (relatively high density) to a gas (much lesser density). This process\nyields a much greater dispersal of matter, since the molecules will occupy a much greater volume after the\nsolid-to-gas transition.\n"]], ["block_16", ["(b) Condensation is the conversion of a gas (relatively low density) to a liquid (much greater density). This\nprocess yields a much lesser dispersal of matter, since the molecules will occupy a much lesser volume after\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["EXAMPLE 16.1\n"]], ["block_19", [{"image_0": "799_0.png", "coords": [130, 206, 481, 274]}]], ["block_20", [{"image_1": "799_1.png", "coords": [130, 496, 481, 620]}]]], "page_800": [["block_0", ["In 1824, at the age of 28, Nicolas L\u00e9onard Sadi Carnot (Figure 16.7) published the results of an extensive study\nregarding the efficiency of steam heat engines. A later review of Carnot\u2019s findings by Rudolf Clausius\nintroduced a new thermodynamic property that relates the spontaneous heat flow accompanying a process to\nthe temperature at which the process takes place. This new property was expressed as the ratio of the\nreversible heat (qrev) and the kelvin temperature (T). In thermodynamics, a reversible process is one that\ntakes place at such a slow rate that it is always at equilibrium and its direction can be changed (it can be\n\u201creversed\u201d) by an infinitesimally small change in some condition. Note that the idea of a reversible process is a\nformalism required to support the development of various thermodynamic concepts; no real processes are\ntruly reversible, rather they are classified as irreversible.\n"]], ["block_1", ["the gas-to-liquid transition.\n"]], ["block_2", ["(c) The process in question is diffusion. This process yields a more uniform dispersal of matter, since the initial\nstate of the system involves two regions of different dye concentrations (high in the drop of dye, zero in the\nwater), and the final state of the system contains a single dye concentration throughout.\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["Describe how energy is redistributed when a spoon at room temperature is placed in a cup of hot coffee.\n"]], ["block_5", [" Answer: \nHeat will spontaneously flow from the hotter object (coffee) to the colder object (spoon), resulting in a more\nuniform distribution of thermal energy as the spoon warms and the coffee cools.\n"]], ["block_6", [" 16.2 Entropy \n"]], ["block_7", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_8", [" FIGURE 16.7 \n(a) Nicholas L\u00e9onard Sadi Carnot\u2019s research into steam-powered machinery and (b) Rudolf Clausius\u2019s\n"]], ["block_9", ["later study of those findings led to groundbreaking discoveries about spontaneous heat flow processes.\n"]], ["block_10", ["Similar to other thermodynamic properties, this new quantity is a state function, so its change depends only\nupon the initial and final states of a system. In 1865, Clausius named this property entropy (S) and defined its\nchange for any process as the following:\n"]], ["block_11", ["\u2022\nDefine entropy\n"]], ["block_12", ["\u2022\nExplain the relationship between entropy and the number of microstates\n"]], ["block_13", ["\u2022\nPredict the sign of the entropy change for chemical and physical processes\n"]], ["block_14", [{"image_0": "800_0.png", "coords": [130, 428, 481, 654]}]], ["block_15", [" 16.2 \u2022 Entropy \n 787 \n"]]], "page_801": [["block_0", [" 788 \n 16 \u2022 Thermodynamics \n"]], ["block_1", ["Consider the general case of a system comprised of N particles distributed among n boxes. The number of\nmicrostates possible for such a system is n. For example, distributing four particles among two boxes will\nresult in 2= 16 different microstates as illustrated in Figure 16.8. Microstates with equivalent particle\narrangements (not considering individual particle identities) are grouped together and are called\ndistributions. The probability that a system will exist with its components in a given distribution is\nproportional to the number of microstates within the distribution. Since entropy increases logarithmically\nwith the number of microstates, the most probable distribution is therefore the one of greatest entropy.\n"]], ["block_2", ["The entropy change for a real, irreversible process is then equal to that for the theoretical reversible process\nthat involves the same initial and final states.\n"]], ["block_3", [" Entropy and Microstates \n"]], ["block_4", ["Following the work of Carnot and Clausius, Ludwig Boltzmann developed a molecular-scale statistical model\nthat related the entropy of a system to the number of microstates (W) possible for the system. A microstate is a\nspecific configuration of all the locations and energies of the atoms or molecules that make up a system. The\nrelation between a system\u2019s entropy and the number of possible microstates is\n"]], ["block_5", ["where k is the Boltzmann constant, 1.38\n10J/K.\n"]], ["block_6", ["As for other state functions, the change in entropy for a process is the difference between its final (Sf) and\ninitial (Si) values:\n"]], ["block_7", ["For processes involving an increase in the number of microstates, Wf > Wi, the entropy of the system increases\nand \u0394S > 0. Conversely, processes that reduce the number of microstates, Wf < Wi, yield a decrease in system\nentropy, \u0394S < 0. This molecular-scale interpretation of entropy provides a link to the probability that a process\nwill occur as illustrated in the next paragraphs.\n"]], ["block_8", [{"image_0": "801_0.png", "coords": [72, 439, 540, 648]}]], ["block_9", [" FIGURE 16.8 \nThe sixteen microstates associated with placing four particles in two boxes are shown. The\n"]], ["block_10", ["microstates are collected into five distributions\u2014(a), (b), (c), (d), and (e)\u2014based on the numbers of particles in each\nbox.\n"]], ["block_11", ["For this system, the most probable configuration is one of the six microstates associated with distribution (c)\nwhere the particles are evenly distributed between the boxes, that is, a configuration of two particles in each\n"]], ["block_12", [" Access for free at openstax.org \n"]]], "page_802": [["block_0", ["box. The probability of finding the system in this configuration is\nor\nThe least probable configuration of\n"]], ["block_1", ["the system is one in which all four particles are in one box, corresponding to distributions (a) and (e), each with\na probability of\nThe probability of finding all particles in only one box (either the left box or right box) is\n"]], ["block_2", ["then\nor\n"]], ["block_3", ["As you add more particles to the system, the number of possible microstates increases exponentially (2). A\nmacroscopic (laboratory-sized) system would typically consist of moles of particles (N ~ 10), and the\ncorresponding number of microstates would be staggeringly huge. Regardless of the number of particles in the\nsystem, however, the distributions in which roughly equal numbers of particles are found in each box are\nalways the most probable configurations.\n"]], ["block_4", ["This matter dispersal model of entropy is often described qualitatively in terms of the disorder of the system.\nBy this description, microstates in which all the particles are in a single box are the most ordered, thus\npossessing the least entropy. Microstates in which the particles are more evenly distributed among the boxes\nare more disordered, possessing greater entropy.\n"]], ["block_5", ["The previous description of an ideal gas expanding into a vacuum (Figure 16.4) is a macroscopic example of\nthis particle-in-a-box model. For this system, the most probable distribution is confirmed to be the one in\nwhich the matter is most uniformly dispersed or distributed between the two flasks. Initially, the gas molecules\nare confined to just one of the two flasks. Opening the valve between the flasks increases the volume available\nto the gas molecules and, correspondingly, the number of microstates possible for the system. Since Wf > Wi,\nthe expansion process involves an increase in entropy (\u0394S > 0) and is spontaneous.\n"]], ["block_6", ["A similar approach may be used to describe the spontaneous flow of heat. Consider a system consisting of two\nobjects, each containing two particles, and two units of thermal energy (represented as \u201c*\u201d) in Figure 16.9. The\nhot object is comprised of particles A and B and initially contains both energy units. The cold object is\ncomprised of particles C and D , which initially has no energy units. Distribution (a) shows the three\nmicrostates possible for the initial state of the system, with both units of energy contained within the hot\nobject. If one of the two energy units is transferred, the result is distribution (b) consisting of four microstates.\nIf both energy units are transferred, the result is distribution (c) consisting of three microstates. Thus, we may\ndescribe this system by a total of ten microstates. The probability that the heat does not flow when the two\nobjects are brought into contact, that is, that the system remains in distribution (a), is\nMore likely is the\n"]], ["block_7", ["flow of heat to yield one of the other two distribution, the combined probability being\nThe most likely result\n"]], ["block_8", ["is the flow of heat to yield the uniform dispersal of energy represented by distribution (b), the probability of\nthis configuration being\nThis supports the common observation that placing hot and cold objects in\n"]], ["block_9", ["contact results in spontaneous heat flow that ultimately equalizes the objects\u2019 temperatures. And, again, this\nspontaneous process is also characterized by an increase in system entropy.\n"]], ["block_10", [" FIGURE 16.9 \nThis shows a microstate model describing the flow of heat from a hot object to a cold object. (a)\n"]], ["block_11", ["Before the heat flow occurs, the object comprised of particles A and B contains both units of energy and as\nrepresented by a distribution of three microstates. (b) If the heat flow results in an even dispersal of energy (one\nenergy unit transferred), a distribution of four microstates results. (c) If both energy units are transferred, the\nresulting distribution has three microstates.\n"]], ["block_12", [{"image_0": "802_0.png", "coords": [130, 522, 481, 657]}]], ["block_13", [" 16.2 \u2022 Entropy \n 789 \n"]]], "page_803": [["block_0", [" 790 \n 16 \u2022 Thermodynamics \n"]], ["block_1", [" Determination of \u0394S \n"]], ["block_2", ["Calculate the change in entropy for the process depicted below.\n"]], ["block_3", [{"image_0": "803_0.png", "coords": [72, 125, 486, 161]}]], ["block_4", [" Solution \n"]], ["block_5", ["The initial number of microstates is one, the final six:\n"]], ["block_6", ["The sign of this result is consistent with expectation; since there are more microstates possible for the final\nstate than for the initial state, the change in entropy should be positive.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["Consider the system shown in Figure 16.9. What is the change in entropy for the process where all the energy\nis transferred from the hot object ( AB ) to the cold object ( CD )?\n"]], ["block_9", [" Answer: \n0 J/K\n"]], ["block_10", [" Predicting the Sign of \u0394S \n"]], ["block_11", ["The relationships between entropy, microstates, and matter/energy dispersal described previously allow us to\nmake generalizations regarding the relative entropies of substances and to predict the sign of entropy changes\nfor chemical and physical processes. Consider the phase changes illustrated in Figure 16.10. In the solid\nphase, the atoms or molecules are restricted to nearly fixed positions with respect to each other and are\ncapable of only modest oscillations about these positions. With essentially fixed locations for the system\u2019s\ncomponent particles, the number of microstates is relatively small. In the liquid phase, the atoms or molecules\nare free to move over and around each other, though they remain in relatively close proximity to one another.\nThis increased freedom of motion results in a greater variation in possible particle locations, so the number of\nmicrostates is correspondingly greater than for the solid. As a result, Sliquid > Ssolid and the process of\nconverting a substance from solid to liquid (melting) is characterized by an increase in entropy, \u0394S > 0. By the\nsame logic, the reciprocal process (freezing) exhibits a decrease in entropy, \u0394S < 0.\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["EXAMPLE 16.2\n"]]], "page_804": [["block_0", [{"image_0": "804_0.png", "coords": [72, 57, 540, 271]}]], ["block_1", [" FIGURE 16.10 \nThe entropy of a substance increases (\u0394S > 0) as it transforms from a relatively ordered solid, to a\n"]], ["block_2", ["less-ordered liquid, and then to a still less-ordered gas. The entropy decreases (\u0394S < 0) as the substance transforms\nfrom a gas to a liquid and then to a solid.\n"]], ["block_3", ["Now consider the gaseous phase, in which a given number of atoms or molecules occupy a much greater\nvolume than in the liquid phase. Each atom or molecule can be found in many more locations, corresponding\nto a much greater number of microstates. Consequently, for any substance, Sgas > Sliquid > Ssolid, and the\nprocesses of vaporization and sublimation likewise involve increases in entropy, \u0394S > 0. Likewise, the\nreciprocal phase transitions, condensation and deposition, involve decreases in entropy, \u0394S < 0.\n"]], ["block_4", ["According to kinetic-molecular theory, the temperature of a substance is proportional to the average kinetic\nenergy of its particles. Raising the temperature of a substance will result in more extensive vibrations of the\nparticles in solids and more rapid translations of the particles in liquids and gases. At higher temperatures, the\ndistribution of kinetic energies among the atoms or molecules of the substance is also broader (more\ndispersed) than at lower temperatures. Thus, the entropy for any substance increases with temperature\n(Figure 16.11).\n"]], ["block_5", [{"image_1": "804_1.png", "coords": [72, 469, 540, 655]}]], ["block_6", [" FIGURE 16.11 \nEntropy increases as the temperature of a substance is raised, which corresponds to the greater\n"]], ["block_7", ["spread of kinetic energies. When a substance undergoes a phase transition, its entropy changes significantly.\n"]], ["block_8", ["Try this simulator (http://openstax.org/l/16freemotion) with interactive visualization of the dependence of\n"]], ["block_9", ["LINK TO LEARNING\n"]], ["block_10", [" 16.2 \u2022 Entropy \n 791 \n"]]], "page_805": [["block_0", [" 792 \n 16 \u2022 Thermodynamics \n"]], ["block_1", ["particle location and freedom of motion on physical state and temperature.\n"]], ["block_2", ["The entropy of a substance is influenced by the structure of the particles (atoms or molecules) that comprise\nthe substance. With regard to atomic substances, heavier atoms possess greater entropy at a given\ntemperature than lighter atoms, which is a consequence of the relation between a particle\u2019s mass and the\nspacing of quantized translational energy levels (a topic beyond the scope of this text). For molecules, greater\nnumbers of atoms increase the number of ways in which the molecules can vibrate and thus the number of\npossible microstates and the entropy of the system.\n"]], ["block_3", ["Finally, variations in the types of particles affects the entropy of a system. Compared to a pure substance, in\nwhich all particles are identical, the entropy of a mixture of two or more different particle types is greater. This\nis because of the additional orientations and interactions that are possible in a system comprised of\nnonidentical components. For example, when a solid dissolves in a liquid, the particles of the solid experience\nboth a greater freedom of motion and additional interactions with the solvent particles. This corresponds to a\nmore uniform dispersal of matter and energy and a greater number of microstates. The process of dissolution\ntherefore involves an increase in entropy, \u0394S > 0.\n"]], ["block_4", ["Considering the various factors that affect entropy allows us to make informed predictions of the sign of \u0394S for\nvarious chemical and physical processes as illustrated in Example 16.3.\n"]], ["block_5", [" Predicting the Sign of \u2206S \n"]], ["block_6", ["Predict the sign of the entropy change for the following processes. Indicate the reason for each of your\npredictions.\n"]], ["block_7", ["(a) One mole liquid water at room temperature\none mole liquid water at 50 \u00b0C\n"]], ["block_8", ["(b)\n"]], ["block_9", ["(c)\n"]], ["block_10", ["(d)\n"]], ["block_11", [" Solution \n"]], ["block_12", ["(a) positive, temperature increases\n"]], ["block_13", ["(b) negative, reduction in the number of ions (particles) in solution, decreased dispersal of matter\n"]], ["block_14", ["(c) negative, net decrease in the amount of gaseous species\n"]], ["block_15", ["(d) positive, phase transition from solid to liquid, net increase in dispersal of matter\n"]], ["block_16", [" Check Your Learning \n"]], ["block_17", ["Predict the sign of the entropy change for the following processes. Give a reason for your prediction.\n"]], ["block_18", ["(a)\n"]], ["block_19", ["(b) the freezing of liquid water\n"]], ["block_20", ["(c)\n"]], ["block_21", ["(d)\n"]], ["block_22", [" Answer: \n(a) Positive; The solid dissolves to give an increase of mobile ions in solution. (b) Negative; The liquid becomes\na more ordered solid. (c) Positive; The relatively ordered solid becomes a gas. (d) Positive; There is a net\nincrease in the amount of gaseous species.\n"]], ["block_23", [" Access for free at openstax.org \n"]], ["block_24", ["EXAMPLE 16.3\n"]]], "page_806": [["block_0", ["These results lead to a profound statement regarding the relation between entropy and spontaneity known as\nthe second law of thermodynamics : all spontaneous changes cause an increase in the entropy of the\nuniverse. A summary of these three relations is provided in Table 16.1.\n"]], ["block_1", [" 16.3 The Second and Third Laws of Thermodynamics \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", [" The Second Law of Thermodynamics \n"]], ["block_4", ["In the quest to identify a property that may reliably predict the spontaneity of a process, a promising candidate\nhas been identified: entropy. Processes that involve an increase in entropy of the system (\u0394S > 0) are very often\nspontaneous; however, examples to the contrary are plentiful. By expanding consideration of entropy changes\nto include the surroundings, we may reach a significant conclusion regarding the relation between this\nproperty and spontaneity. In thermodynamic models, the system and surroundings comprise everything, that\nis, the universe, and so the following is true:\n"]], ["block_5", ["To illustrate this relation, consider again the process of heat flow between two objects, one identified as the\nsystem and the other as the surroundings. There are three possibilities for such a process:\n"]], ["block_6", ["1.\nThe objects are at different temperatures, and heat flows from the hotter to the cooler object. This is\nalways observed to occur spontaneously. Designating the hotter object as the system and invoking the\ndefinition of entropy yields the following:\n"]], ["block_7", ["2.\nThe objects are at different temperatures, and heat flows from the cooler to the hotter object. This is never\nobserved to occur spontaneously. Again designating the hotter object as the system and invoking the\ndefinition of entropy yields the following:\n"]], ["block_8", ["3.\nThe objects are at essentially the same temperature, Tsys \u2248 Tsurr, and so the magnitudes of the entropy\nchanges are essentially the same for both the system and the surroundings. In this case, the entropy\nchange of the universe is zero, and the system is at equilibrium.\n"]], ["block_9", ["\u2022\nState and explain the second and third laws of thermodynamics\n"]], ["block_10", ["\u2022\nCalculate entropy changes for phase transitions and chemical reactions under standard conditions\n"]], ["block_11", ["The magnitudes of \u2212qrev and qrev are equal, their opposite arithmetic signs denoting loss of heat by the\nsystem and gain of heat by the surroundings. Since Tsys > Tsurr in this scenario, the entropy decrease of the\nsystem will be less than the entropy increase of the surroundings, and so the entropy of the universe will\nincrease:\n"]], ["block_12", ["The arithmetic signs of qrev denote the gain of heat by the system and the loss of heat by the surroundings.\nThe magnitude of the entropy change for the surroundings will again be greater than that for the system,\nbut in this case, the signs of the heat changes (that is, the direction of the heat flow) will yield a negative\nvalue for \u0394Suniv. This process involves a decrease in the entropy of the universe.\n"]], ["block_13", [" 16.3 \u2022 The Second and Third Laws of Thermodynamics \n 793 \n"]]], "page_807": [["block_0", [" 794 \n 16 \u2022 Thermodynamics \n"]], ["block_1", ["Suniv < 0, so melting is nonspontaneous (not spontaneous) at \u221210.0 \u00b0C.\n"]], ["block_2", ["Suniv > 0, so melting is spontaneous at 10.00 \u00b0C.\n"]], ["block_3", ["For many realistic applications, the surroundings are vast in comparison to the system. In such cases, the heat\ngained or lost by the surroundings as a result of some process represents a very small, nearly infinitesimal,\nfraction of its total thermal energy. For example, combustion of a fuel in air involves transfer of heat from a\nsystem (the fuel and oxygen molecules undergoing reaction) to surroundings that are infinitely more massive\n(the earth\u2019s atmosphere). As a result, qsurr is a good approximation of qrev, and the second law may be stated as\nthe following:\n"]], ["block_4", ["We may use this equation to predict the spontaneity of a process as illustrated in Example 16.4.\n"]], ["block_5", [" Will Ice Spontaneously Melt? \n"]], ["block_6", ["The entropy change for the process\n"]], ["block_7", ["is 22.1 J/K and requires that the surroundings transfer 6.00 kJ of heat to the system. Is the process\nspontaneous at \u221210.00 \u00b0C? Is it spontaneous at +10.00 \u00b0C?\n"]], ["block_8", [" Solution \n"]], ["block_9", ["We can assess the spontaneity of the process by calculating the entropy change of the universe. If \u0394Suniv is\npositive, then the process is spontaneous. At both temperatures, \u0394Ssys = 22.1 J/K and qsurr = \u22126.00 kJ.\n"]], ["block_10", ["At \u221210.00 \u00b0C (263.15 K), the following is true:\n"]], ["block_11", ["At 10.00 \u00b0C (283.15 K), the following is true:\n"]], ["block_12", [" Check Your Learning \n"]], ["block_13", ["Using this information, determine if liquid water will spontaneously freeze at the same temperatures. What\ncan you say about the values of Suniv?\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["EXAMPLE 16.4\n"]], ["block_16", [" TABLE 16.1 \n"]], ["block_17", ["\u0394Suniv > 0\nspontaneous\n"]], ["block_18", ["\u0394Suniv < 0\nnonspontaneous (spontaneous in opposite direction)\n"]], ["block_19", ["\u0394Suniv = 0\nat equilibrium\n"]], ["block_20", ["The Second Law of Thermodynamics\n"]]], "page_808": [["block_0", ["This limiting condition for a system\u2019s entropy represents the third law of thermodynamics : the entropy of a\npure, perfect crystalline substance at 0 K is zero.\n"]], ["block_1", [" Answer: \nEntropy is a state function, so \u0394Sfreezing = \u2212\u0394Smelting = \u221222.1 J/K and qsurr = +6.00 kJ. At \u221210.00 \u00b0C spontaneous,\n+0.7 J/K; at +10.00 \u00b0C nonspontaneous, \u22120.9 J/K.\n"]], ["block_2", [" The Third Law of Thermodynamics \n"]], ["block_3", ["The previous section described the various contributions of matter and energy dispersal that contribute to the\nentropy of a system. With these contributions in mind, consider the entropy of a pure, perfectly crystalline\nsolid possessing no kinetic energy (that is, at a temperature of absolute zero, 0 K). This system may be\ndescribed by a single microstate, as its purity, perfect crystallinity and complete lack of motion means there is\nbut one possible location for each identical atom or molecule comprising the crystal (W = 1). According to the\nBoltzmann equation, the entropy of this system is zero.\n"]], ["block_4", ["Careful calorimetric measurements can be made to determine the temperature dependence of a substance\u2019s\nentropy and to derive absolute entropy values under specific conditions. Standard entropies (S\u00b0) are for one\nmole of substance under standard conditions (a pressure of 1 bar and a temperature of 298.15 K; see details\nregarding standard conditions in the thermochemistry chapter of this text). The standard entropy change \n ( \u0394 S\u00b0) for a reaction may be computed using standard entropies as shown below:\n"]], ["block_5", ["where \u03bd represents stoichiometric coefficients in the balanced equation representing the process. For\nexample, \u0394S\u00b0 for the following reaction at room temperature\n"]], ["block_6", ["is computed as:\n"]], ["block_7", ["A partial listing of standard entropies is provided in Table 16.2, and additional values are provided in\nAppendix G. The example exercises that follow demonstrate the use of S\u00b0 values in calculating standard\nentropy changes for physical and chemical processes.\n"]], ["block_8", [" Substance \n (J mol \u22121 K \u22121 ) \n"]], ["block_9", ["carbon\n"]], ["block_10", ["C(s, graphite)\n5.740\n"]], ["block_11", ["C(s, diamond)\n2.38\n"]], ["block_12", ["CO(g)\n197.7\n"]], ["block_13", ["CO2(g)\n213.8\n"]], ["block_14", ["CH4(g)\n186.3\n"]], ["block_15", ["C2H4(g)\n219.5\n"]], ["block_16", ["C2H6(g)\n229.5\n"]], ["block_17", [" 16.3 \u2022 The Second and Third Laws of Thermodynamics \n 795 \n"]]], "page_809": [["block_0", [" 796 \n 16 \u2022 Thermodynamics \n"]], ["block_1", [" TABLE 16.2 Standard entropies for selected substances measured at 1 atm and 298.15 K. (Values are\napproximately equal to those measured at 1 bar, the currently accepted standard state pressure.)\n"]], ["block_2", [" Determination of \u0394S\u00b0 \n"]], ["block_3", ["Calculate the standard entropy change for the following process:\n"]], ["block_4", [" Solution \n"]], ["block_5", ["Calculate the entropy change using standard entropies as shown above:\n"]], ["block_6", ["The value for \u0394S\u00b0 is negative, as expected for this phase transition (condensation), which the previous section\ndiscussed.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["Calculate the standard entropy change for the following process:\n"]], ["block_9", [" Answer: \n\u2212120.6 J Kmol\n"]], ["block_10", [" Determination of \u0394S\u00b0 \n"]], ["block_11", ["Calculate the standard entropy change for the combustion of methanol, CH3OH:\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["CH3OH(l)\n126.8\n"]], ["block_14", ["C2H5OH(l)\n160.7\n"]], ["block_15", ["hydrogen\n"]], ["block_16", ["H2(g)\n130.57\n"]], ["block_17", ["H(g)\n114.6\n"]], ["block_18", ["H2O(g)\n188.71\n"]], ["block_19", ["H2O(l)\n69.91\n"]], ["block_20", ["HCI(g)\n186.8\n"]], ["block_21", ["H2S(g)\n205.7\n"]], ["block_22", ["oxygen\n"]], ["block_23", ["O2(g)\n205.03\n"]], ["block_24", ["EXAMPLE 16.5\n"]], ["block_25", ["EXAMPLE 16.6\n"]]], "page_810": [["block_0", [" Solution \n"]], ["block_1", ["Calculate the entropy change using standard entropies as shown above:\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["Calculate the standard entropy change for the following reaction:\n"]], ["block_4", [" Answer: \n24.7 J/K\n"]], ["block_5", [" 16.4 Free Energy \n"]], ["block_6", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_7", ["One of the challenges of using the second law of thermodynamics to determine if a process is spontaneous is\nthat it requires measurements of the entropy change for the system and the entropy change for the\nsurroundings. An alternative approach involving a new thermodynamic property defined in terms of system\nproperties only was introduced in the late nineteenth century by American mathematician Josiah Willard\nGibbs. This new property is called the Gibbs free energy (G) (or simply the free energy), and it is defined in\nterms of a system\u2019s enthalpy and entropy as the following:\n"]], ["block_8", ["Free energy is a state function, and at constant temperature and pressure, the free energy change ( \u0394 G) may\nbe expressed as the following:\n"]], ["block_9", ["(For simplicity\u2019s sake, the subscript \u201csys\u201d will be omitted henceforth.)\n"]], ["block_10", ["The relationship between this system property and the spontaneity of a process may be understood by\nrecalling the previously derived second law expression:\n"]], ["block_11", ["The first law requires that qsurr = \u2212qsys, and at constant pressure qsys = \u0394H, so this expression may be rewritten\nas:\n"]], ["block_12", ["Multiplying both sides of this equation by \u2212T, and rearranging yields the following:\n"]], ["block_13", ["\u2022\nDefine Gibbs free energy, and describe its relation to spontaneity\n"]], ["block_14", ["\u2022\nCalculate free energy change for a process using free energies of formation for its reactants and products\n"]], ["block_15", ["\u2022\nCalculate free energy change for a process using enthalpies of formation and the entropies for its reactants and\nproducts\n"]], ["block_16", ["\u2022\nExplain how temperature affects the spontaneity of some processes\n"]], ["block_17", ["\u2022\nRelate standard free energy changes to equilibrium constants\n"]], ["block_18", [" 16.4 \u2022 Free Energy \n 797 \n"]]], "page_811": [["block_0", [" 798 \n 16 \u2022 Thermodynamics \n"]], ["block_1", ["However, as noted previously in this chapter, such conditions are not realistic. In addition, the technologies\nused to extract work from a spontaneous process (e.g., automobile engine, steam turbine) are never 100%\nefficient, and so the work done by these processes is always less than the theoretical maximum. Similar\nreasoning may be applied to a nonspontaneous process, for which the free energy change represents the\nminimum amount of work that must be done on the system to carry out the process.\n"]], ["block_2", ["Comparing this equation to the previous one for free energy change shows the following relation:\n"]], ["block_3", ["The free energy change is therefore a reliable indicator of the spontaneity of a process, being directly related to\nthe previously identified spontaneity indicator, \u0394Suniv. Table 16.3 summarizes the relation between the\nspontaneity of a process and the arithmetic signs of these indicators.\n"]], ["block_4", [" What\u2019s \u201cFree\u201d about \u0394G? \n"]], ["block_5", ["In addition to indicating spontaneity, the free energy change also provides information regarding the amount\nof useful work (w) that may be accomplished by a spontaneous process. Although a rigorous treatment of this\nsubject is beyond the scope of an introductory chemistry text, a brief discussion is helpful for gaining a better\nperspective on this important thermodynamic property.\n"]], ["block_6", ["For this purpose, consider a spontaneous, exothermic process that involves a decrease in entropy. The free\nenergy, as defined by\n"]], ["block_7", ["may be interpreted as representing the difference between the energy produced by the process, \u0394H, and the\nenergy lost to the surroundings, T\u0394S. The difference between the energy produced and the energy lost is the\nenergy available (or \u201cfree\u201d) to do useful work by the process, \u0394G. If the process somehow could be made to take\nplace under conditions of thermodynamic reversibility, the amount of work that could be done would be\nmaximal:\n"]], ["block_8", [" Calculating Free Energy Change \n"]], ["block_9", ["Free energy is a state function, so its value depends only on the conditions of the initial and final states of the\nsystem. A convenient and common approach to the calculation of free energy changes for physical and\nchemical reactions is by use of widely available compilations of standard state thermodynamic data. One\nmethod involves the use of standard enthalpies and entropies to compute standard free energy changes, \n \u0394 G\u00b0 , according to the following relation.\n"]], ["block_10", [" Using Standard Enthalpy and Entropy Changes to Calculate \u0394G\u00b0 \n"]], ["block_11", ["Use standard enthalpy and entropy data from Appendix G to calculate the standard free energy change for the\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["EXAMPLE 16.7\n"]], ["block_14", [" TABLE 16.3 \n"]], ["block_15", ["Relation between Process Spontaneity and Signs of Thermodynamic Properties\n"]], ["block_16", ["\u0394Suniv > 0\n\u0394G < 0\nspontaneous\n"]], ["block_17", ["\u0394Suniv < 0\n\u0394G > 0\nnonspontaneous\n"]], ["block_18", ["\u0394Suniv = 0\n\u0394G = 0\nat equilibrium\n"]]], "page_812": [["block_0", ["vaporization of water at room temperature (298 K). What does the computed value for \u0394G\u00b0 say about the\nspontaneity of this process?\n"]], ["block_1", [" Solution \n"]], ["block_2", ["The process of interest is the following:\n"]], ["block_3", ["The standard change in free energy may be calculated using the following equation:\n"]], ["block_4", ["From Appendix G:\n"]], ["block_5", ["Using the appendix data to calculate the standard enthalpy and entropy changes yields:\n"]], ["block_6", ["Substitution into the standard free energy equation yields:\n"]], ["block_7", ["At 298 K (25 \u00b0C)\nso boiling is nonspontaneous (not spontaneous).\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["Use standard enthalpy and entropy data from Appendix G to calculate the standard free energy change for the\nreaction shown here (298 K). What does the computed value for \u0394G\u00b0 say about the spontaneity of this process?\n"]], ["block_10", [" Answer: \n"]], ["block_11", ["The standard free energy change for a reaction may also be calculated from standard free energy of \n formation \u0394 G f \u00b0 values of the reactants and products involved in the reaction. The standard free energy of\nformation is the free energy change that accompanies the formation of one mole of a substance from its\nelements in their standard states. Similar to the standard enthalpy of formation,\nis by definition zero for\n"]], ["block_12", ["elemental substances in their standard states. The approach used to calculate\nfor a reaction from\n"]], ["block_13", ["values is the same as that demonstrated previously for enthalpy and entropy changes. For the reaction\n"]], ["block_14", ["the standard free energy change at room temperature may be calculated as\n"]], ["block_15", ["the reaction is nonspontaneous (not spontaneous) at 25 \u00b0C.\n"]], ["block_16", [" Substance \n"]], ["block_17", ["H2O(g)\n\u2212241.82\n188.8\n"]], ["block_18", ["H2O(l)\n\u2212285.83\n70.0\n"]], ["block_19", [" 16.4 \u2022 Free Energy \n 799 \n"]]], "page_813": [["block_0", [" 800 \n 16 \u2022 Thermodynamics \n"]], ["block_1", [" Using Standard Free Energies of Formation to Calculate \u0394G\u00b0 \n"]], ["block_2", ["Consider the decomposition of yellow mercury(II) oxide.\n"]], ["block_3", ["Calculate the standard free energy change at room temperature,\nusing (a) standard free energies of\n"]], ["block_4", ["formation and (b) standard enthalpies of formation and standard entropies. Do the results indicate the\nreaction to be spontaneous or nonspontaneous under standard conditions?\n"]], ["block_5", [" Solution \n"]], ["block_6", ["The required data are available in Appendix G and are shown here.\n"]], ["block_7", ["(a) Using free energies of formation:\n"]], ["block_8", ["(b) Using enthalpies and entropies of formation:\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["EXAMPLE 16.8\n"]], ["block_11", ["HgO (s, yellow)\n\u221258.43\n\u221290.46\n71.13\n"]], ["block_12", [" Compound \n"]], ["block_13", ["O2(g)\n0\n0\n205.2\n"]], ["block_14", ["Hg(l)\n0\n0\n75.9\n"]]], "page_814": [["block_0", ["Both ways to calculate the standard free energy change at 25 \u00b0C give the same numerical value (to three\nsignificant figures), and both predict that the process is nonspontaneous (not spontaneous) at room\ntemperature.\n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["Calculate \u0394G\u00b0 using (a) free energies of formation and (b) enthalpies of formation and entropies (Appendix G).\nDo the results indicate the reaction to be spontaneous or nonspontaneous at 25 \u00b0C?\n"]], ["block_3", [" Answer: \n(a) 140.8 kJ/mol, nonspontaneous\n"]], ["block_4", ["(b) 141.5 kJ/mol, nonspontaneous\n"]], ["block_5", [" Free Energy Changes for Coupled Reactions \n"]], ["block_6", ["The use of free energies of formation to compute free energy changes for reactions as described above is\npossible because \u0394G is a state function, and the approach is analogous to the use of Hess\u2019 Law in computing\nenthalpy changes (see the chapter on thermochemistry). Consider the vaporization of water as an example:\n"]], ["block_7", ["An equation representing this process may be derived by adding the formation reactions for the two phases of\nwater (necessarily reversing the reaction for the liquid phase). The free energy change for the sum reaction is\nthe sum of free energy changes for the two added reactions:\n"]], ["block_8", ["This approach may also be used in cases where a nonspontaneous reaction is enabled by coupling it to a\nspontaneous reaction. For example, the production of elemental zinc from zinc sulfide is thermodynamically\nunfavorable, as indicated by a positive value for \u0394G\u00b0:\n"]], ["block_9", ["The industrial process for production of zinc from sulfidic ores involves coupling this decomposition reaction\nto the thermodynamically favorable oxidation of sulfur:\n"]], ["block_10", ["The coupled reaction exhibits a negative free energy change and is spontaneous:\n"]], ["block_11", ["This process is typically carried out at elevated temperatures, so this result obtained using standard free\nenergy values is just an estimate. The gist of the calculation, however, holds true.\n"]], ["block_12", [" 16.4 \u2022 Free Energy \n 801 \n"]]], "page_815": [["block_0", [" 802 \n 16 \u2022 Thermodynamics \n"]], ["block_1", [" Calculating Free Energy Change for a Coupled Reaction \n"]], ["block_2", ["Is a reaction coupling the decomposition of ZnS to the formation of H2S expected to be spontaneous under\nstandard conditions?\n"]], ["block_3", [" Solution \n"]], ["block_4", ["Following the approach outlined above and using free energy values from Appendix G:\n"]], ["block_5", ["The coupled reaction exhibits a positive free energy change and is thus nonspontaneous.\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["What is the standard free energy change for the reaction below? Is the reaction expected to be spontaneous\nunder standard conditions?\n"]], ["block_8", [" Answer: \n\u2212199.7 kJ; spontaneous\n"]], ["block_9", [" Temperature Dependence of Spontaneity \n"]], ["block_10", ["As was previously demonstrated in this chapter\u2019s section on entropy, the spontaneity of a process may depend\nupon the temperature of the system. Phase transitions, for example, will proceed spontaneously in one\ndirection or the other depending upon the temperature of the substance in question. Likewise, some chemical\nreactions can also exhibit temperature dependent spontaneities. To illustrate this concept, the equation\nrelating free energy change to the enthalpy and entropy changes for the process is considered:\n"]], ["block_11", ["The spontaneity of a process, as reflected in the arithmetic sign of its free energy change, is then determined\nby the signs of the enthalpy and entropy changes and, in some cases, the absolute temperature. Since T is the\nabsolute (kelvin) temperature, it can only have positive values. Four possibilities therefore exist with regard to\nthe signs of the enthalpy and entropy changes:\n"]], ["block_12", ["These four scenarios are summarized in Figure 16.12.\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", ["1.\n Both \u0394 H and \u0394 S are positive. This condition describes an endothermic process that involves an increase\nin system entropy. In this case, \u0394G will be negative if the magnitude of the T\u0394S term is greater than \u0394H. If\nthe T\u0394S term is less than \u0394H, the free energy change will be positive. Such a process is spontaneous at\nhigh temperatures and nonspontaneous at low temperatures.\n"]], ["block_15", ["2.\n Both \u0394 H and \u0394 S are negative. This condition describes an exothermic process that involves a decrease in\nsystem entropy. In this case, \u0394G will be negative if the magnitude of the T\u0394S term is less than \u0394H. If the\nT\u0394S term\u2019s magnitude is greater than \u0394H, the free energy change will be positive. Such a process is\nspontaneous at low temperatures and nonspontaneous at high temperatures.\n"]], ["block_16", ["3.\n \u0394 H is positive and \u0394 S is negative. This condition describes an endothermic process that involves a\ndecrease in system entropy. In this case, \u0394G will be positive regardless of the temperature. Such a process\nis nonspontaneous at all temperatures.\n"]], ["block_17", ["4.\n \u0394 H is negative and \u0394 S is positive. This condition describes an exothermic process that involves an\nincrease in system entropy. In this case, \u0394G will be negative regardless of the temperature. Such a process\nis spontaneous at all temperatures.\n"]], ["block_18", ["EXAMPLE 16.9\n"]]], "page_816": [["block_0", [{"image_0": "816_0.png", "coords": [72, 57, 540, 228]}]], ["block_1", [" Predicting the Temperature Dependence of Spontaneity \n"]], ["block_2", ["The incomplete combustion of carbon is described by the following equation:\n"]], ["block_3", ["How does the spontaneity of this process depend upon temperature?\n"]], ["block_4", [" Solution \n"]], ["block_5", ["Combustion processes are exothermic (\u0394H < 0). This particular reaction involves an increase in entropy due to\nthe accompanying increase in the amount of gaseous species (net gain of one mole of gas, \u0394S > 0). The reaction\nis therefore spontaneous (\u0394G < 0) at all temperatures.\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["Popular chemical hand warmers generate heat by the air-oxidation of iron:\n"]], ["block_8", ["How does the spontaneity of this process depend upon temperature?\n"]], ["block_9", [" Answer: \n\u0394H and \u0394S are negative; the reaction is spontaneous at low temperatures.\n"]], ["block_10", ["When considering the conclusions drawn regarding the temperature dependence of spontaneity, it is\nimportant to keep in mind what the terms \u201chigh\u201d and \u201clow\u201d mean. Since these terms are adjectives, the\ntemperatures in question are deemed high or low relative to some reference temperature. A process that is\nnonspontaneous at one temperature but spontaneous at another will necessarily undergo a change in\n\u201cspontaneity\u201d (as reflected by its \u0394G) as temperature varies. This is clearly illustrated by a graphical\npresentation of the free energy change equation, in which \u0394G is plotted on the y axis versus T on the x axis:\n"]], ["block_11", ["Such a plot is shown in Figure 16.13. A process whose enthalpy and entropy changes are of the same\narithmetic sign will exhibit a temperature-dependent spontaneity as depicted by the two yellow lines in the\nplot. Each line crosses from one spontaneity domain (positive or negative \u0394G) to the other at a temperature\nthat is characteristic of the process in question. This temperature is represented by the x-intercept of the line,\nthat is, the value of T for which \u0394G is zero:\n"]], ["block_12", ["EXAMPLE 16.10\n"]], ["block_13", [" FIGURE 16.12 \nThere are four possibilities regarding the signs of enthalpy and entropy changes.\n"]], ["block_14", [" 16.4 \u2022 Free Energy \n 803 \n"]]], "page_817": [["block_0", [" 804 \n 16 \u2022 Thermodynamics \n"]], ["block_1", ["So, saying a process is spontaneous at \u201chigh\u201d or \u201clow\u201d temperatures means the temperature is above or below,\nrespectively, that temperature at which \u0394G for the process is zero. As noted earlier, the condition of \u0394G = 0\ndescribes a system at equilibrium.\n"]], ["block_2", [" FIGURE 16.13 \nThese plots show the variation in \u0394G with temperature for the four possible combinations of\n"]], ["block_3", ["arithmetic sign for \u0394H and \u0394S.\n"]], ["block_4", [" Equilibrium Temperature for a Phase Transition \n"]], ["block_5", ["As defined in the chapter on liquids and solids, the boiling point of a liquid is the temperature at which its\nliquid and gaseous phases are in equilibrium (that is, when vaporization and condensation occur at equal\nrates). Use the information in Appendix G to estimate the boiling point of water.\n"]], ["block_6", [" Solution \n"]], ["block_7", ["The process of interest is the following phase change:\n"]], ["block_8", ["When this process is at equilibrium, \u0394G = 0, so the following is true:\n"]], ["block_9", ["Using the standard thermodynamic data from Appendix G,\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["EXAMPLE 16.11\n"]], ["block_12", [{"image_0": "817_0.png", "coords": [189, 130, 423, 436]}]]], "page_818": [["block_0", ["The free energy change for a process taking place with reactants and products present under nonstandard\nconditions (pressures other than 1 bar; concentrations other than 1 M) is related to the standard free energy\nchange according to this equation:\n"]], ["block_1", ["R is the gas constant (8.314 J/K mol), T is the kelvin or absolute temperature, and Q is the reaction quotient.\nFor gas phase equilibria, the pressure-based reaction quotient, QP, is used. The concentration-based reaction\nquotient, QC, is used for condensed phase equilibria. This equation may be used to predict the spontaneity for\na process under any given set of conditions as illustrated in Example 16.12.\n"]], ["block_2", ["T = 25 \u00b0C,\nand\n"]], ["block_3", ["The accepted value for water\u2019s normal boiling point is 373.2 K (100.0 \u00b0C), and so this calculation is in\nreasonable agreement. Note that the values for enthalpy and entropy changes data used were derived from\nstandard data at 298 K (Appendix G). If desired, you could obtain more accurate results by using enthalpy and\nentropy changes determined at (or at least closer to) the actual boiling point.\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["Use the information in Appendix G to estimate the boiling point of CS2.\n"]], ["block_6", [" Answer: \n313 K (accepted value 319 K)\n"]], ["block_7", [" Free Energy and Equilibrium \n"]], ["block_8", ["The free energy change for a process may be viewed as a measure of its driving force. A negative value for \u0394G\nrepresents a driving force for the process in the forward direction, while a positive value represents a driving\nforce for the process in the reverse direction. When \u0394G is zero, the forward and reverse driving forces are\nequal, and the process occurs in both directions at the same rate (the system is at equilibrium).\n"]], ["block_9", ["In the chapter on equilibrium the reaction quotient, Q, was introduced as a convenient measure of the status of\nan equilibrium system. Recall that Q is the numerical value of the mass action expression for the system, and\nthat you may use its value to identify the direction in which a reaction will proceed in order to achieve\nequilibrium. When Q is lesser than the equilibrium constant, K, the reaction will proceed in the forward\ndirection until equilibrium is reached and Q = K. Conversely, if Q > K, the process will proceed in the reverse\ndirection until equilibrium is achieved.\n"]], ["block_10", [" Calculating \u0394G under Nonstandard Conditions \n"]], ["block_11", ["What is the free energy change for the process shown here under the specified conditions?\n"]], ["block_12", [" Solution \n"]], ["block_13", ["The equation relating free energy change to standard free energy change and reaction quotient may be used\ndirectly:\n"]], ["block_14", ["EXAMPLE 16.12\n"]], ["block_15", [" 16.4 \u2022 Free Energy \n 805 \n"]]], "page_819": [["block_0", [" 806 \n 16 \u2022 Thermodynamics \n"]], ["block_1", ["Since the computed value for \u0394G is positive, the reaction is nonspontaneous under these conditions.\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["Calculate the free energy change for this same reaction at 875 \u00b0C in a 5.00 L mixture containing 0.100 mol of\neach gas. Is the reaction spontaneous under these conditions?\n"]], ["block_4", [" Answer: \n\u0394G = \u2013123.5 kJ/mol; yes\n"]], ["block_5", ["For a system at equilibrium, Q = K and \u0394G = 0, and the previous equation may be written as\n"]], ["block_6", ["This form of the equation provides a useful link between these two essential thermodynamic properties, and it\ncan be used to derive equilibrium constants from standard free energy changes and vice versa. The relations\nbetween standard free energy changes and equilibrium constants are summarized in Table 16.4.\n"]], ["block_7", [" Calculating an Equilibrium Constant using Standard Free Energy Change \n"]], ["block_8", ["Given that the standard free energies of formation of Ag(aq), Cl(aq), and AgCl(s) are 77.1 kJ/mol, \u2212131.2 kJ/\nmol, and \u2212109.8 kJ/mol, respectively, calculate the solubility product, Ksp, for AgCl.\n"]], ["block_9", [" Solution \n"]], ["block_10", ["The reaction of interest is the following:\n"]], ["block_11", ["The standard free energy change for this reaction is first computed using standard free energies of formation\nfor its reactants and products:\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["EXAMPLE 16.13\n"]], ["block_14", [" TABLE 16.4 \n"]], ["block_15", ["Relations between Standard Free Energy Changes and Equilibrium Constants\n"]], ["block_16", ["> 1\n< 0\nProducts are more abundant\n"]], ["block_17", ["< 1\n> 0\nReactants are more abundant\n"]], ["block_18", ["= 1\n= 0\nReactants and products are comparably abundant\n"]], ["block_19", [" K \n \u0394G\u00b0 \n Composition of an Equilibrium Mixture \n"]]], "page_820": [["block_0", [" Answer: \nK = 6.9\n"]], ["block_1", ["The equilibrium constant for the reaction may then be derived from its standard free energy change:\n"]], ["block_2", ["This result is in reasonable agreement with the value provided in Appendix J.\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["Use the thermodynamic data provided in Appendix G to calculate the equilibrium constant for the dissociation\nof dinitrogen tetroxide at 25 \u00b0C.\n"]], ["block_5", ["To further illustrate the relation between these two essential thermodynamic concepts, consider the\nobservation that reactions spontaneously proceed in a direction that ultimately establishes equilibrium. As\nmay be shown by plotting the free energy versus the extent of the reaction (for example, as reflected in the\nvalue of Q), equilibrium is established when the system\u2019s free energy is minimized (Figure 16.14). If a system\nconsists of reactants and products in nonequilibrium amounts (Q \u2260 K), the reaction will proceed\nspontaneously in the direction necessary to establish equilibrium.\n"]], ["block_6", [" 16.4 \u2022 Free Energy \n 807 \n"]]], "page_821": [["block_0", [" 808 \n 16 \u2022 Thermodynamics \n"]], ["block_1", [{"image_0": "821_0.png", "coords": [72, 57, 540, 526]}]], ["block_2", [" FIGURE 16.14 \nThese plots show the free energy versus reaction progress for systems whose standard free energy\n"]], ["block_3", ["changes are (a) negative, (b) positive, and (c) zero. Nonequilibrium systems will proceed spontaneously in whatever\ndirection is necessary to minimize free energy and establish equilibrium.\n"]], ["block_4", [" Access for free at openstax.org \n"]]], "page_822": [["block_0", [" Key Terms \n"]], ["block_1", [" entropy (S) state function that is a measure of the\n"]], ["block_2", [" Gibbs free energy change (G) \nthermodynamic\n"]], ["block_3", [" microstate possible configuration or arrangement\n"]], ["block_4", [" nonspontaneous process process that requires\n"]], ["block_5", [" reversible process process that takes place so\n"]], ["block_6", [" second law of thermodynamics \nall spontaneous\n"]], ["block_7", [" Key Equations \n"]], ["block_8", [" Summary \n"]], ["block_9", [" 16.1 Spontaneity \n"]], ["block_10", ["Chemical and physical processes have a natural\ntendency to occur in one direction under certain\nconditions. A spontaneous process occurs without\nthe need for a continual input of energy from some\nexternal source, while a nonspontaneous process\nrequires such. Systems undergoing a spontaneous\nprocess may or may not experience a gain or loss of\nenergy, but they will experience a change in the way\nmatter and/or energy is distributed within the\nsystem.\n"]], ["block_11", [" 16.2 Entropy \n"]], ["block_12", ["Entropy (S) is a state function that can be related to\n"]], ["block_13", ["S = k ln W\n"]], ["block_14", ["\u0394Suniv = \u0394Ssys + \u0394Ssurr\n"]], ["block_15", ["\u0394G = \u0394H \u2212 T\u0394S\n"]], ["block_16", ["matter and/or energy dispersal within a system,\ndetermined by the number of system microstates;\noften described as a measure of the disorder of\nthe system\n"]], ["block_17", ["property defined in terms of system enthalpy and\nentropy; all spontaneous processes involve a\ndecrease in G\n"]], ["block_18", ["of matter and energy within a system\n"]], ["block_19", ["continual input of energy from an external source\n"]], ["block_20", ["slowly as to be capable of reversing direction in\nresponse to an infinitesimally small change in\nconditions; hypothetical construct that can only\nbe approximated by real processes\n"]], ["block_21", ["processes involve an increase in the entropy of\nthe universe\n"]], ["block_22", [" spontaneous change \nprocess that takes place\n"]], ["block_23", [" standard entropy (S\u00b0) \nentropy for one mole of a\n"]], ["block_24", [" standard entropy change ( \u0394 S\u00b0) \nchange in entropy\n"]], ["block_25", [" standard free energy change ( \u0394 G\u00b0) \nchange in free\n"]], ["block_26", [" standard free energy of formation \nchange\n"]], ["block_27", [" third law of thermodynamics \nentropy of a perfect\n"]], ["block_28", ["the number of microstates for a system (the number\nof ways the system can be arranged) and to the ratio\nof reversible heat to kelvin temperature. It may be\ninterpreted as a measure of the dispersal or\ndistribution of matter and/or energy in a system,\nand it is often described as representing the\n\u201cdisorder\u201d of the system.\n"]], ["block_29", ["For a given substance, entropy depends on phase\nwith Ssolid < Sliquid < Sgas. For different substances in\nthe same physical state at a given temperature,\nentropy is typically greater for heavier atoms or\nmore complex molecules. Entropy increases when a\nsystem is heated and when solutions form. Using\nthese guidelines, the sign of entropy changes for\n"]], ["block_30", ["without a continuous input of energy from an\nexternal source\n"]], ["block_31", ["substance at 1 bar pressure; tabulated values are\nusually determined at 298.15 K\n"]], ["block_32", ["for a reaction calculated using the standard\nentropies\n"]], ["block_33", ["energy for a process occurring under standard\nconditions (1 bar pressure for gases, 1 M\nconcentration for solutions)\n"]], ["block_34", ["in free energy accompanying the formation of one\nmole of substance from its elements in their\nstandard states\n"]], ["block_35", ["crystal at absolute zero (0 K) is zero\n"]], ["block_36", [" 16 \u2022 Key Terms \n 809 \n"]]], "page_823": [["block_0", [" 810 \n 16 \u2022 Exercises \n"]], ["block_1", ["some chemical reactions and physical changes may\nbe reliably predicted.\n"]], ["block_2", [" 16.3 The Second and Third Laws of \n Thermodynamics \n"]], ["block_3", ["The second law of thermodynamics states that a\nspontaneous process increases the entropy of the\nuniverse, Suniv > 0. If \u0394Suniv < 0, the process is\nnonspontaneous, and if \u0394Suniv = 0, the system is at\nequilibrium. The third law of thermodynamics\nestablishes the zero for entropy as that of a perfect,\npure crystalline solid at 0 K. With only one possible\nmicrostate, the entropy is zero. We may compute the\n"]], ["block_4", [" Exercises \n"]], ["block_5", [" 16.1 Spontaneity \n"]], ["block_6", [" 16.2 Entropy \n"]], ["block_7", [" 10 . Consider the system shown in Figure 16.9. What is the change in entropy for the process where the energy\n"]], ["block_8", [" 11 . Consider the system shown in Figure 16.9. What is the change in entropy for the process where the energy\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", [" 1 . What is a spontaneous reaction?\n 2 . What is a nonspontaneous reaction?\n 3 . Indicate whether the following processes are spontaneous or nonspontaneous.\n"]], ["block_11", [" 4 . A helium-filled balloon spontaneously deflates overnight as He atoms diffuse through the wall of the\n"]], ["block_12", [" 5 . Many plastic materials are organic polymers that contain carbon and hydrogen. The oxidation of these\n"]], ["block_13", [" 6 . In Figure 16.8 all possible distributions and microstates are shown for four different particles shared\n"]], ["block_14", [" 7 . In Figure 16.8 all of the possible distributions and microstates are shown for four different particles\n"]], ["block_15", [" 8 . How does the process described in the previous item relate to the system shown in Figure 16.4?\n 9 . Consider a system similar to the one in Figure 16.8, except that it contains six particles instead of four.\n"]], ["block_16", ["(a) Liquid water freezing at a temperature below its freezing point\n(b) Liquid water freezing at a temperature above its freezing point\n(c) The combustion of gasoline\n(d) A ball thrown into the air\n(e) A raindrop falling to the ground\n(f) Iron rusting in a moist atmosphere\n"]], ["block_17", ["balloon. Describe the redistribution of matter and/or energy that accompanies this process.\n"]], ["block_18", ["plastics in air to form carbon dioxide and water is a spontaneous process; however, plastic materials tend\nto persist in the environment. Explain.\n"]], ["block_19", ["between two boxes. Determine the entropy change, \u0394S, if the particles are initially evenly distributed\nbetween the two boxes, but upon redistribution all end up in Box (b).\n"]], ["block_20", ["shared between two boxes. Determine the entropy change, \u0394S, for the system when it is converted from\ndistribution (b) to distribution (d).\n"]], ["block_21", ["What is the probability of having all the particles in only one of the two boxes in the case? Compare this\nwith the similar probability for the system of four particles that we have derived to be equal to\nWhat\n"]], ["block_22", ["does this comparison tell us about even larger systems?\n"]], ["block_23", ["is initially associated only with particle A, but in the final state the energy is distributed between two\ndifferent particles?\n"]], ["block_24", ["is initially associated with particles A and B, and the energy is distributed between two particles in\ndifferent boxes (one in A-B, the other in C-D)?\n"]], ["block_25", ["standard entropy change for a process by using\nstandard entropy values for the reactants and\nproducts involved in the process.\n"]], ["block_26", [" 16.4 Free Energy \n"]], ["block_27", ["Gibbs free energy (G) is a state function defined with\nregard to system quantities only and may be used to\npredict the spontaneity of a process. A negative\nvalue for \u0394G indicates a spontaneous process; a\npositive \u0394G indicates a nonspontaneous process;\nand a \u0394G of zero indicates that the system is at\nequilibrium. A number of approaches to the\ncomputation of free energy changes are possible.\n"]]], "page_824": [["block_0", [" 12 . Arrange the following sets of systems in order of increasing entropy. Assume one mole of each substance\n"]], ["block_1", [" 13 . At room temperature, the entropy of the halogens increases from I2 to Br2 to Cl2. Explain.\n 14 . Consider two processes: sublimation of I2(s) and melting of I2(s) (Note: the latter process can occur at the\n"]], ["block_2", [" 15 . Indicate which substance in the given pairs has the higher entropy value. Explain your choices.\n"]], ["block_3", [" 16 . Predict the sign of the entropy change for the following processes.\n"]], ["block_4", [" 17 . Predict the sign of the entropy change for the following processes. Give a reason for your prediction.\n"]], ["block_5", [" 18 . Write the balanced chemical equation for the combustion of methane, CH4(g), to give carbon dioxide and\n"]], ["block_6", [" 19 . Write the balanced chemical equation for the combustion of benzene, C6H6(l), to give carbon dioxide and\n"]], ["block_7", [" 16.3 The Second and Third Laws of Thermodynamics \n"]], ["block_8", [" 20 . What is the difference between \u0394S and \u0394S\u00b0 for a chemical change?\n 21 . Calculate\nfor the following changes.\n"]], ["block_9", [" 22 . Determine the entropy change for the combustion of liquid ethanol, C2H5OH, under the standard\n"]], ["block_10", [" 23 . Determine the entropy change for the combustion of gaseous propane, C3H8, under the standard\n"]], ["block_11", [" 24 . \u201cThermite\u201d reactions have been used for welding metal parts such as railway rails and in metal refining.\n"]], ["block_12", [" 25 . Using the relevant\nvalues listed in Appendix G, calculate\nfor the following changes:\n"]], ["block_13", ["and the same temperature for each member of a set.\n(a) H2(g), HBrO4(g), HBr(g)\n(b) H2O(l), H2O(g), H2O(s)\n(c) He(g), Cl2(g), P4(g)\n"]], ["block_14", ["same temperature but somewhat higher pressure).\n"]], ["block_15", ["Is \u0394S positive or negative in these processes? In which of the processes will the magnitude of the entropy\nchange be greater?\n"]], ["block_16", ["(a) C2H5OH(l) or C3H7OH(l)\n(b) C2H5OH(l) or C2H5OH(g)\n(c) 2H(g) or H(g)\n"]], ["block_17", ["(a) An ice cube is warmed to near its melting point.\n(b) Exhaled breath forms fog on a cold morning.\n(c) Snow melts.\n"]], ["block_18", ["(a)\n(b)\n"]], ["block_19", ["(c)\n"]], ["block_20", ["water vapor. Explain why it is difficult to predict whether \u0394S is positive or negative for this chemical\nreaction.\n"]], ["block_21", ["water vapor. Would you expect \u0394S to be positive or negative in this process?\n"]], ["block_22", ["(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n(g)\n"]], ["block_23", ["conditions to give gaseous carbon dioxide and liquid water.\n"]], ["block_24", ["conditions to give gaseous carbon dioxide and water.\n"]], ["block_25", ["One such thermite reaction is\nIs the reaction spontaneous at\n"]], ["block_26", ["room temperature under standard conditions? During the reaction, the surroundings absorb 851.8 kJ/mol\nof heat.\n"]], ["block_27", ["(a)\n(b)\n"]], ["block_28", [" 16 \u2022 Exercises \n 811 \n"]]], "page_825": [["block_0", [" 812 \n 16 \u2022 Exercises \n"]], ["block_1", [" 26 . From the following information, determine\nfor the following:\n"]], ["block_2", [" 27 . By calculating \u0394Suniv at each temperature, determine if the melting of 1 mole of NaCl(s) is spontaneous at\n"]], ["block_3", [" 28 . Use the standard entropy data in Appendix G to determine the change in entropy for each of the following\n"]], ["block_4", [" 29 . Use the standard entropy data in Appendix G to determine the change in entropy for each of the following\n"]], ["block_5", [" 16.4 Free Energy \n"]], ["block_6", [" 30 . What is the difference between \u0394G and \u0394G\u00b0 for a chemical change?\n 31 . A reaction has\n= 100 kJ/mol and\nIs the reaction spontaneous at room\n"]], ["block_7", [" 32 . Explain what happens as a reaction starts with \u0394G < 0 (negative) and reaches the point where \u0394G = 0.\n 33 . Use the standard free energy of formation data in Appendix G to determine the free energy change for\n"]], ["block_8", [" 34 . Use the standard free energy data in Appendix G to determine the free energy change for each of the\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["500 \u00b0C and at 700 \u00b0C.\n"]], ["block_11", ["What assumptions are made about the thermodynamic information (entropy and enthalpy values) used to\nsolve this problem?\n"]], ["block_12", ["reactions. All the processes occur at the standard conditions and 25 \u00b0C.\n(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n"]], ["block_13", ["reactions. All the processes occur at the standard conditions and 25 \u00b0C.\n(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n"]], ["block_14", ["temperature? If not, under what temperature conditions will it become spontaneous?\n"]], ["block_15", ["each of the following reactions, which are run under standard state conditions and 25 \u00b0C. Identify each as\neither spontaneous or nonspontaneous at these conditions.\n(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n"]], ["block_16", ["following reactions, which are run under standard state conditions and 25 \u00b0C. Identify each as either\nspontaneous or nonspontaneous at these conditions.\n(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n"]]], "page_826": [["block_0", [" 35 . Given:\n"]], ["block_1", [" 36 . Is the formation of ozone (O3(g)) from oxygen (O2(g)) spontaneous at room temperature under standard\n"]], ["block_2", [" 37 . Consider the decomposition of red mercury(II) oxide under standard state conditions.\n"]], ["block_3", [" 38 . Among other things, an ideal fuel for the control thrusters of a space vehicle should decompose in a\n"]], ["block_4", [" 39 . Calculate \u0394G\u00b0 for each of the following reactions from the equilibrium constant at the temperature given.\n"]], ["block_5", [" 40 . Calculate \u0394G\u00b0 for each of the following reactions from the equilibrium constant at the temperature given.\n"]], ["block_6", [" 41 . Calculate the equilibrium constant at 25 \u00b0C for each of the following reactions from the value of \u0394G\u00b0 given.\n"]], ["block_7", [" 42 . Calculate the equilibrium constant at 25 \u00b0C for each of the following reactions from the value of \u0394G\u00b0 given.\n"]], ["block_8", [" 43 . Calculate the equilibrium constant at the temperature given.\n"]], ["block_9", ["(a) Determine the standard free energy of formation,\nfor phosphoric acid.\n"]], ["block_10", ["(b) How does your calculated result compare to the value in Appendix G? Explain.\n"]], ["block_11", ["state conditions?\n"]], ["block_12", ["(a) Is the decomposition spontaneous under standard state conditions?\n(b) Above what temperature does the reaction become spontaneous?\n"]], ["block_13", ["spontaneous exothermic reaction when exposed to the appropriate catalyst. Evaluate the following\nsubstances under standard state conditions as suitable candidates for fuels.\n(a) Ammonia:\n(b) Diborane:\n(c) Hydrazine:\n(d) Hydrogen peroxide:\n"]], ["block_14", ["(a)\n(b)\n(c)\n(d)\n"]], ["block_15", ["(e)\n"]], ["block_16", ["(f)\n"]], ["block_17", ["(a)\n(b)\n(c)\n"]], ["block_18", ["(d)\n(e)\n"]], ["block_19", ["(f)\n"]], ["block_20", ["(a)\n(b)\n(c)\n(d)\n(e)\n"]], ["block_21", ["(a)\n(b)\n(c)\n(d)\n(e)\n"]], ["block_22", ["(a)\n(b)\n(c)\n(d)\n(e)\n"]], ["block_23", [" 16 \u2022 Exercises \n 813 \n"]]], "page_827": [["block_0", [" 814 \n 16 \u2022 Exercises \n"]], ["block_1", [" 44 . Calculate the equilibrium constant at the temperature given.\n"]], ["block_2", [" 45 . Consider the following reaction at 298 K:\n"]], ["block_3", [" 46 . Determine the normal boiling point (in kelvin) of dichloromethane, CH2Cl2. Find the actual boiling point\n"]], ["block_4", [" 47 . Under what conditions is\nspontaneous?\n"]], ["block_5", [" 48 . At room temperature, the equilibrium constant (Kw) for the self-ionization of water is 1.00\n10. Using\n"]], ["block_6", [" 49 . Hydrogen sulfide is a pollutant found in natural gas. Following its removal, it is converted to sulfur by the\n"]], ["block_7", [" 50 . Consider the decomposition of CaCO3(s) into CaO(s) and CO2(g). What is the equilibrium partial pressure\n"]], ["block_8", [" 51 . In the laboratory, hydrogen chloride (HCl(g)) and ammonia (NH3(g)) often escape from bottles of their\n"]], ["block_9", [" 52 . Benzene can be prepared from acetylene.\nDetermine the equilibrium constant at\n"]], ["block_10", [" 53 . Carbon dioxide decomposes into CO and O2 at elevated temperatures. What is the equilibrium partial\n"]], ["block_11", [" 54 . Carbon tetrachloride, an important industrial solvent, is prepared by the chlorination of methane at 850\n"]], ["block_12", [" 55 . Acetic acid, CH3CO2H, can form a dimer, (CH3CO2H)2, in the gas phase.\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", ["(a)\n(b)\n(c)\n(d)\n(e)\n"]], ["block_15", ["What is the standard free energy change at this temperature? Describe what happens to the initial system,\nwhere the reactants and products are in standard states, as it approaches equilibrium.\n"]], ["block_16", ["using the Internet or some other source, and calculate the percent error in the temperature. Explain the\ndifferences, if any, between the two values.\n"]], ["block_17", ["this information, calculate the standard free energy change for the aqueous reaction of hydrogen ion with\nhydroxide ion to produce water. (Hint: The reaction is the reverse of the self-ionization reaction.)\n"]], ["block_18", ["reaction\nWhat is the equilibrium constant for this\n"]], ["block_19", ["reaction? Is the reaction endothermic or exothermic?\n"]], ["block_20", ["of CO2 at room temperature?\n"]], ["block_21", ["solutions and react to form the ammonium chloride (NH4Cl(s)), the white glaze often seen on glassware.\nAssuming that the number of moles of each gas that escapes into the room is the same, what is the\nmaximum partial pressure of HCl and NH3 in the laboratory at room temperature? (Hint: The partial\npressures will be equal and are at their maximum value when at equilibrium.)\n"]], ["block_22", ["25 \u00b0C and at 850 \u00b0C. Is the reaction spontaneous at either of these temperatures? Why is all acetylene not\nfound as benzene?\n"]], ["block_23", ["pressure of oxygen in a sample at 1000 \u00b0C for which the initial pressure of CO2 was 1.15 atm?\n"]], ["block_24", ["K.\n"]], ["block_25", ["What is the equilibrium constant for the reaction at 850 K? Would the reaction vessel need to be heated or\ncooled to keep the temperature of the reaction constant?\n"]], ["block_26", ["The dimer is held together by two hydrogen bonds with a total strength of 66.5 kJ per mole of dimer.\n"]], ["block_27", [{"image_0": "827_0.png", "coords": [91, 564, 325, 611]}]], ["block_28", ["At 25 \u00b0C, the equilibrium constant for the dimerization is 1.3\n10(pressure in atm). What is \u0394S\u00b0 for the\n"]], ["block_29", ["reaction?\n"]]], "page_828": [["block_0", [" 56 . Determine \u0394G\u00ba for the following reactions.\n"]], ["block_1", [" 57 . Given that the\nfor Pb(aq) and Cl(aq) is \u221224.3 kJ/mole and \u2212131.2 kJ/mole respectively, determine\n"]], ["block_2", [" 58 . Determine the standard free energy change,\nfor the formation of S(aq) given that the\nfor\n"]], ["block_3", [" 59 . Determine the standard enthalpy change, entropy change, and free energy change for the conversion of\n"]], ["block_4", [" 60 . The evaporation of one mole of water at 298 K has a standard free energy change of 8.58 kJ.\n"]], ["block_5", [" 61 . In glycolysis, the reaction of glucose (Glu) to form glucose-6-phosphate (G6P) requires ATP to be present\n"]], ["block_6", [" 62 . One of the important reactions in the biochemical pathway glycolysis is the reaction of\n"]], ["block_7", [" 63 . Without doing a numerical calculation, determine which of the following will reduce the free energy\n"]], ["block_8", [" 64 . When ammonium chloride is added to water and stirred, it dissolves spontaneously and the resulting\n"]], ["block_9", ["(a) Antimony pentachloride decomposes at 448 \u00b0C. The reaction is:\n"]], ["block_10", ["An equilibrium mixture in a 5.00 L flask at 448 \u00b0C contains 3.85 g of SbCl5, 9.14 g of SbCl3, and 2.84 g of\nCl2.\n(b) Chlorine molecules dissociate according to this reaction:\n"]], ["block_11", ["1.00% of Cl2 molecules dissociate at 975 K and a pressure of 1.00 atm.\n"]], ["block_12", ["the solubility product, Ksp, for PbCl2(s).\n"]], ["block_13", ["Ag(aq) and Ag2S(s) are 77.1 kJ/mole and \u221239.5 kJ/mole respectively, and the solubility product for Ag2S(s)\nis 8\n10.\n"]], ["block_14", ["diamond to graphite. Discuss the spontaneity of the conversion with respect to the enthalpy and entropy\nchanges. Explain why diamond spontaneously changing into graphite is not observed.\n"]], ["block_15", ["(a) Is the evaporation of water under standard thermodynamic conditions spontaneous?\n(b) Determine the equilibrium constant, KP, for this physical process.\n(c) By calculating \u2206G, determine if the evaporation of water at 298 K is spontaneous when the partial\npressure of water,\nis 0.011 atm.\n"]], ["block_16", ["(d) If the evaporation of water were always nonspontaneous at room temperature, wet laundry would\nnever dry when placed outside. In order for laundry to dry, what must be the value of\nin the air?\n"]], ["block_17", ["as described by the following equation:\n"]], ["block_18", ["In this process, ATP becomes ADP summarized by the following equation:\n"]], ["block_19", ["Determine the standard free energy change for the following reaction, and explain why ATP is necessary\nto drive this process:\n"]], ["block_20", ["glucose-6-phosphate (G6P) to form fructose-6-phosphate (F6P):\n"]], ["block_21", ["(a) Is the reaction spontaneous or nonspontaneous under standard thermodynamic conditions?\n(b) Standard thermodynamic conditions imply the concentrations of G6P and F6P to be 1 M, however, in a\ntypical cell, they are not even close to these values. Calculate \u0394G when the concentrations of G6P and F6P\nare 120 \u03bcM and 28 \u03bcM respectively, and discuss the spontaneity of the forward reaction under these\nconditions. Assume the temperature is 37 \u00b0C.\n"]], ["block_22", ["change for the reaction, that is, make it less positive or more negative, when the temperature is increased.\nExplain.\n(a)\n(b)\n(c)\n(d)\n"]], ["block_23", ["solution feels cold. Without doing any calculations, deduce the signs of \u0394G, \u0394H, and \u0394S for this process,\nand justify your choices.\n"]], ["block_24", [" 16 \u2022 Exercises \n 815 \n"]]], "page_829": [["block_0", [" 816 \n 16 \u2022 Exercises \n"]], ["block_1", [" 65 . An important source of copper is from the copper ore, chalcocite, a form of copper(I) sulfide. When heated,\n"]], ["block_2", [" 66 . What happens to\n(becomes more negative or more positive) for the following chemical reactions when\n"]], ["block_3", [" Access for free at openstax.org \n"]], ["block_4", ["the Cu2S decomposes to form copper and sulfur described by the following equation:\n"]], ["block_5", ["(a) Determine\nfor the decomposition of Cu2S(s).\n"]], ["block_6", ["(b) The reaction of sulfur with oxygen yields sulfur dioxide as the only product. Write an equation that\ndescribes this reaction, and determine\nfor the process.\n"]], ["block_7", ["(c) The production of copper from chalcocite is performed by roasting the Cu2S in air to produce the Cu.\nBy combining the equations from Parts (a) and (b), write the equation that describes the roasting of the\nchalcocite, and explain why coupling these reactions together makes for a more efficient process for the\nproduction of the copper.\n"]], ["block_8", ["the partial pressure of oxygen is increased?\n(a)\n(b)\n(c)\n"]]], "page_830": [["block_0", ["CHAPTER 17\nElectrochemistry\n"]], ["block_1", [{"image_0": "830_0.png", "coords": [72, 104, 622, 358]}]], ["block_2", [" Figure 17.1 \nElectric vehicles are powered by batteries, devices that harness the energy of spontaneous redox\n"]], ["block_3", ["reactions. (credit: modification of work by Robert Couse-Baker)\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 17.1 Review of Redox Chemistry \n 17.2 Galvanic Cells \n 17.3 Electrode and Cell Potentials \n 17.4 Potential, Free Energy, and Equilibrium \n 17.5 Batteries and Fuel Cells \n 17.6 Corrosion \n 17.7 Electrolysis \n"]], ["block_6", [" INTRODUCTION \n"]], ["block_7", ["reactions. This important reaction class is defined by changes in oxidation states for one or more reactant\nelements, and it includes a subset of reactions involving the transfer of electrons between reactant species.\nAround the turn of the nineteenth century, chemists began exploring ways these electrons could be\ntransferred indirectly via an external circuit rather than directly via intimate contact of redox reactants. In the\ntwo centuries since, the field of electrochemistry has evolved to yield significant insights on the fundamental\naspects of redox chemistry as well as a wealth of technologies ranging from industrial-scale metallurgical\nprocesses to robust, rechargeable batteries for electric vehicles (Figure 17.1). In this chapter, the essential\nconcepts of electrochemistry will be addressed.\n"]], ["block_8", ["Another chapter in this text introduced the chemistry of reduction-oxidation (redox)\n"]]], "page_831": [["block_0", [" 818 \n 17 \u2022 Electrochemistry \n"]], ["block_1", ["By definition, a redox reaction is one that entails changes in oxidation number (or oxidation state) for one or\nmore of the elements involved. The oxidation number of an element in a compound is essentially an\nassessment of how the electronic environment of its atoms is different in comparison to atoms of the pure\nelement. By this description, the oxidation number of an atom in an element is equal to zero. For an atom in a\ncompound, the oxidation number is equal to the charge the atom would have in the compound if the\ncompound were ionic. Consequential to these rules, the sum of oxidation numbers for all atoms in a molecule\nis equal to the charge on the molecule. To illustrate this formalism, examples from the two compound classes,\nionic and covalent, will be considered.\n"]], ["block_2", [" 17.1 Review of Redox Chemistry \n"]], ["block_3", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_4", ["Since reactions involving electron transfer are essential to the topic of electrochemistry, a brief review of redox\nchemistry is provided here that summarizes and extends the content of an earlier text chapter (see chapter on\nreaction stoichiometry). Readers wishing additional review are referred to the text chapter on reaction\nstoichiometry.\n"]], ["block_5", [" Oxidation Numbers \n"]], ["block_6", ["Simple ionic compounds present the simplest examples to illustrate this formalism, since by definition the\nelements\u2019 oxidation numbers are numerically equivalent to ionic charges. Sodium chloride, NaCl, is comprised\nof Nacations and Clanions, and so oxidation numbers for sodium and chlorine are, +1 and \u22121, respectively.\nCalcium fluoride, CaF2, is comprised of Cacations and Fanions, and so oxidation numbers for calcium and\nfluorine are, +2 and \u22121, respectively.\n"]], ["block_7", ["Covalent compounds require a more challenging use of the formalism. Water is a covalent compound whose\nmolecules consist of two H atoms bonded separately to a central O atom via polar covalent O\u2212H bonds. The\nshared electrons comprising an O\u2212H bond are more strongly attracted to the more electronegative O atom, and\nso it acquires a partial negative charge in the water molecule (relative to an O atom in elemental oxygen).\nConsequently, H atoms in a water molecule exhibit partial positive charges compared to H atoms in elemental\nhydrogen. The sum of the partial negative and partial positive charges for each water molecule is zero, and the\nwater molecule is neutral.\n"]], ["block_8", ["Imagine that the polarization of shared electrons within the O\u2212H bonds of water were 100% complete\u2014the\nresult would be transfer of electrons from H to O, and water would be an ionic compound comprised of O\n"]], ["block_9", ["anions and Hcations. And so, the oxidations numbers for oxygen and hydrogen in water are \u22122 and +1,\nrespectively. Applying this same logic to carbon tetrachloride, CCl4, yields oxidation numbers of +4 for carbon\nand \u22121 for chlorine. In the nitrate ion,\n, the oxidation number for nitrogen is +5 and that for oxygen is \u22122,\n"]], ["block_10", ["summing to equal the 1\u2212 charge on the molecule:\n"]], ["block_11", [" Balancing Redox Equations \n"]], ["block_12", ["The unbalanced equation below describes the decomposition of molten sodium chloride:\n"]], ["block_13", ["This reaction satisfies the criterion for redox classification, since the oxidation number for Na is decreased\nfrom +1 to 0 (it undergoes reduction) and that for Cl is increased from \u22121 to 0 (it undergoes oxidation). The\nequation in this case is easily balanced by inspection, requiring stoichiometric coefficients of 2 for the NaCl\nand Na:\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["\u2022\nDescribe defining traits of redox chemistry\n"]], ["block_16", ["\u2022\nIdentify the oxidant and reductant of a redox reaction\n"]], ["block_17", ["\u2022\nBalance chemical equations for redox reactions using the half-reaction method\n"]]], "page_832": [["block_0", ["Redox reactions that take place in aqueous solutions are commonly encountered in electrochemistry, and\nmany involve water or its characteristic ions, H(aq) and OH(aq), as reactants or products. In these cases,\nequations representing the redox reaction can be very challenging to balance by inspection, and the use of a\nsystematic approach called the half-reaction method is helpful. This approach involves the following steps:\n"]], ["block_1", ["The examples below demonstrate the application of this method to balancing equations for aqueous redox\nreactions.\n"]], ["block_2", [" Balancing Equations for Redox Reactions in Acidic Solutions \n"]], ["block_3", ["Write the balanced equation representing reaction between solid copper and nitric acid to yield aqueous\ncopper(II) ions and nitrogen monoxide gas.\n"]], ["block_4", [" Solution \n"]], ["block_5", ["Following the steps of the half-reaction method:\n"]], ["block_6", ["1.\nWrite skeletal equations for the oxidation and reduction half-reactions.\n"]], ["block_7", ["2.\nBalance each half-reaction for all elements except H and O.\n"]], ["block_8", ["3.\nBalance each half-reaction for O by adding H2O.\n"]], ["block_9", ["4.\nBalance each half-reaction for H by adding H.\n"]], ["block_10", ["5.\nBalance each half-reaction for charge by adding electrons.\n"]], ["block_11", ["6.\nIf necessary, multiply one or both half-reactions so that the number of electrons consumed in one is equal\nto the number produced in the other.\n"]], ["block_12", ["7.\nAdd the two half-reactions and simplify.\n"]], ["block_13", ["8.\nIf the reaction takes place in a basic medium, add OHions the equation obtained in step 7 to neutralize\nthe Hions (add in equal numbers to both sides of the equation) and simplify.\n"]], ["block_14", ["1.\nWrite skeletal equations for the oxidation and reduction half-reactions.\n"]], ["block_15", ["2.\nBalance each half-reaction for all elements except H and O.\n"]], ["block_16", ["3.\nBalance each half-reaction for O by adding H2O.\n"]], ["block_17", ["4.\nBalance each half-reaction for H by adding H.\n"]], ["block_18", ["5.\nBalance each half-reaction for charge by adding electrons.\n"]], ["block_19", ["6.\nIf necessary, multiply one or both half-reactions so that the number of electrons consumed in one is equal\nto the number produced in the other.\n"]], ["block_20", ["7.\nAdd the two half-reactions and simplify.\n"]], ["block_21", ["8.\nIf the reaction takes place in a basic medium, add OHions the equation obtained in step 7 to neutralize\nthe Hions (add in equal numbers to both sides of the equation) and simplify.\n"]], ["block_22", ["EXAMPLE 17.1\n"]], ["block_23", [" 17.1 \u2022 Review of Redox Chemistry \n 819 \n"]]], "page_833": [["block_0", [" 820 \n 17 \u2022 Electrochemistry \n"]], ["block_1", ["The balanced equation for the reaction in an acidic solution is then\n"]], ["block_2", [" Check Your Learning \n"]], ["block_3", ["The reaction above results when using relatively diluted nitric acid. If concentrated nitric acid is used,\nnitrogen dioxide is produced instead of nitrogen monoxide. Write a balanced equation for this reaction.\n"]], ["block_4", [" Answer: \n"]], ["block_5", [" Balancing Equations for Redox Reactions in Basic Solutions \n"]], ["block_6", ["Write the balanced equation representing reaction between aqueous permanganate ion,\n, and solid\n"]], ["block_7", ["chromium(III) hydroxide, Cr(OH)3, to yield solid manganese(IV) oxide, MnO2, and aqueous chromate ion,\n"]], ["block_8", [" Solution \n"]], ["block_9", ["Following the steps of the half-reaction method:\n"]], ["block_10", [" Check Your Learning \n"]], ["block_11", ["Aqueous permanganate ion may also be reduced using aqueous bromide ion, Br, the products of this reaction\nbeing solid manganese(IV) oxide and aqueous bromate ion, BrO3. Write the balanced equation for this\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["1.\nWrite skeletal equations for the oxidation and reduction half-reactions.\n"]], ["block_14", ["2.\nBalance each half-reaction for all elements except H and O.\n"]], ["block_15", ["3.\nBalance each half-reaction for O by adding H2O.\n"]], ["block_16", ["4.\nBalance each half-reaction for H by adding H.\n"]], ["block_17", ["5.\nBalance each half-reaction for charge by adding electrons.\n"]], ["block_18", ["6.\nIf necessary, multiply one or both half-reactions so that the number of electrons consumed in one is equal\nto the number produced in the other.\nThis step is not necessary since the number of electrons is already in balance.\n"]], ["block_19", ["7.\nAdd the two half-reactions and simplify.\n"]], ["block_20", ["8.\nIf the reaction takes place in a basic medium, add OHions the equation obtained in step 7 to neutralize\nthe Hions (add in equal numbers to both sides of the equation) and simplify.\n"]], ["block_21", ["This step not necessary since the solution is stipulated to be acidic.\n"]], ["block_22", ["EXAMPLE 17.2\n"]], ["block_23", ["The reaction takes place in a basic solution.\n"]]], "page_834": [["block_0", ["These observations are consistent with (i) the oxidation of elemental copper to yield copper(II) ions, Cu(aq),\nwhich impart a blue color to the solution, and (ii) the reduction of silver(I) ions to yield elemental silver, which\ndeposits as a fluffy solid on the copper wire surface. And so, the direct transfer of electrons from the copper\nwire to the aqueous silver ions is spontaneous under the employed conditions. A summary of this redox\nsystem is provided by these equations:\n"]], ["block_1", ["reaction occurring in a basic medium.\n"]], ["block_2", [" Answer: \n"]], ["block_3", [" 17.2 Galvanic Cells \n"]], ["block_4", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_5", ["As demonstration of spontaneous chemical change, Figure 17.2 shows the result of immersing a coiled wire of\ncopper into an aqueous solution of silver nitrate. A gradual but visually impressive change spontaneously\noccurs as the initially colorless solution becomes increasingly blue, and the initially smooth copper wire\nbecomes covered with a porous gray solid.\n"]], ["block_6", [" FIGURE 17.2 \nA copper wire and an aqueous solution of silver nitrate (left) are brought into contact (center) and a\n"]], ["block_7", ["spontaneous transfer of electrons occurs, creating blue Cu(aq) and gray Ag(s) (right).\n"]], ["block_8", ["Consider the construction of a device that contains all the reactants and products of a redox system like the\none here, but prevents physical contact between the reactants. Direct transfer of electrons is, therefore,\nprevented; transfer, instead, takes place indirectly through an external circuit that contacts the separated\nreactants. Devices of this sort are generally referred to as electrochemical cells, and those in which a\nspontaneous redox reaction takes place are called galvanic cells (or voltaic cells ).\n"]], ["block_9", ["A galvanic cell based on the spontaneous reaction between copper and silver(I) is depicted in Figure 17.3. The\ncell is comprised of two half-cells , each containing the redox conjugate pair (\u201ccouple\u201d) of a single reactant. The\nhalf-cell shown at the left contains the Cu(0)/Cu(II) couple in the form of a solid copper foil and an aqueous\nsolution of copper nitrate. The right half-cell contains the Ag(I)/Ag(0) couple as solid silver foil and an aqueous\nsilver nitrate solution. An external circuit is connected to each half-cell at its solid foil, meaning the Cu and Ag\nfoil each function as an electrode. By definition, the anode of an electrochemical cell is the electrode at which\noxidation occurs (in this case, the Cu foil) and the cathode is the electrode where reduction occurs (the Ag foil).\nThe redox reactions in a galvanic cell occur only at the interface between each half-cell\u2019s reaction mixture and\nits electrode. To keep the reactants separate while maintaining charge-balance, the two half-cell solutions are\nconnected by a tube filled with inert electrolyte solution called a salt bridge . The spontaneous reaction in this\ncell produces Cucations in the anode half-cell and consumes Agions in the cathode half-cell, resulting in a\ncompensatory flow of inert ions from the salt bridge that maintains charge balance. Increasing concentrations\nof Cuin the anode half-cell are balanced by an influx of NO3from the salt bridge, while a flow of Nainto the\ncathode half-cell compensates for the decreasing Agconcentration.\n"]], ["block_10", ["\u2022\nDescribe the function of a galvanic cell and its components\n"]], ["block_11", ["\u2022\nUse cell notation to symbolize the composition and construction of galvanic cells\n"]], ["block_12", [{"image_0": "834_0.png", "coords": [130, 261, 481, 327]}]], ["block_13", [" 17.2 \u2022 Galvanic Cells \n 821 \n"]]], "page_835": [["block_0", [" 822 \n 17 \u2022 Electrochemistry \n"]], ["block_1", [" Cell Notation \n"]], ["block_2", ["Abbreviated symbolism is commonly used to represent a galvanic cell by providing essential information on\nits composition and structure. These symbolic representations are called cell notations or cell schematics ,\nand they are written following a few guidelines:\n"]], ["block_3", ["A verbal description of the cell as viewed from anode-to-cathode is often a useful first-step in writing its\nschematic. For example, the galvanic cell shown in Figure 17.3 consists of a solid copper anode immersed in\nan aqueous solution of copper(II) nitrate that is connected via a salt bridge to an aqueous silver(I) nitrate\nsolution, immersed in which is a solid silver cathode. Converting this statement to symbolism following the\nabove guidelines results in the cell schematic:\n"]], ["block_4", ["Consider a different galvanic cell (see Figure 17.4) based on the spontaneous reaction between solid\nmagnesium and aqueous iron(III) ions:\n"]], ["block_5", ["In this cell, a solid magnesium anode is immersed in an aqueous solution of magnesium chloride that is\nconnected via a salt bridge to an aqueous solution containing a mixture of iron(III) chloride and iron(II)\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", ["\u2022\nThe relevant components of each half-cell are represented by their chemical formulas or element symbols\n"]], ["block_8", ["\u2022\nAll interfaces between component phases are represented by vertical parallel lines; if two or more\ncomponents are present in the same phase, their formulas are separated by commas\n"]], ["block_9", ["\u2022\nBy convention, the schematic begins with the anode and proceeds left-to-right identifying phases and\ninterfaces encountered within the cell, ending with the cathode\n"]], ["block_10", [" FIGURE 17.3 \nA galvanic cell based on the spontaneous reaction between copper and silver(I) ions.\n"]], ["block_11", [{"image_0": "835_0.png", "coords": [130, 57, 481, 374]}]]], "page_836": [["block_0", ["chloride, immersed in which is a platinum cathode. The cell schematic is then written as\n"]], ["block_1", ["Notice the cathode half-cell is different from the others considered thus far in that its electrode is comprised of\na substance (Pt) that is neither a reactant nor a product of the cell reaction. This is required when neither\nmember of the half-cell\u2019s redox couple can reasonably function as an electrode, which must be electrically\nconductive and in a phase separate from the half-cell solution. In this case, both members of the redox couple\nare solute species, and so Pt is used as an inert electrode that can simply provide or accept electrons to redox\nspecies in solution. Electrodes constructed from a member of the redox couple, such as the Mg anode in this\ncell, are called active electrodes .\n"]], ["block_2", [{"image_0": "836_0.png", "coords": [72, 191, 540, 501]}]], ["block_3", [" Writing Galvanic Cell Schematics \n"]], ["block_4", ["A galvanic cell is fabricated by connecting two half-cells with a salt bridge, one in which a chromium wire is\nimmersed in a 1 M CrCl3 solution and another in which a copper wire is immersed in 1 M CuCl2. Assuming the\nchromium wire functions as an anode, write the schematic for this cell along with equations for the anode half-\nreaction, the cathode half-reaction, and the overall cell reaction.\n"]], ["block_5", [" Solution \n"]], ["block_6", ["Since the chromium wire is stipulated to be the anode, the schematic begins with it and proceeds left-to-right,\nsymbolizing the other cell components until ending with the copper wire cathode:\n"]], ["block_7", ["The half-reactions for this cell are\n"]], ["block_8", [" FIGURE 17.4 \nA galvanic cell based on the spontaneous reaction between magnesium and iron(III) ions.\n"]], ["block_9", ["EXAMPLE 17.3\n"]], ["block_10", [" 17.2 \u2022 Galvanic Cells \n 823 \n"]]], "page_837": [["block_0", [" 824 \n 17 \u2022 Electrochemistry \n"]], ["block_1", ["When measured for purposes of electrochemistry, a potential reflects the driving force for a specific type of\ncharge transfer process, namely, the transfer of electrons between redox reactants. Considering the nature of\npotential in this context, it is clear that the potential of a single half-cell or a single electrode can\u2019t be\nmeasured; \u201ctransfer\u201d of electrons requires both a donor and recipient, in this case a reductant and an oxidant,\nrespectively. Instead, a half-cell potential may only be assessed relative to that of another half-cell. It is only the\ndifference in potential between two half-cells that may be measured, and these measured potentials are called\n cell potentials, E cell , defined as\n"]], ["block_2", ["Multiplying to make the number of electrons lost by Cr and gained by Cuequal yields\n"]], ["block_3", ["Adding the half-reaction equations and simplifying yields an equation for the cell reaction:\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["Omitting solute concentrations and spectator ion identities, write the schematic for a galvanic cell whose net\ncell reaction is shown below.\n"]], ["block_6", [" Answer: \n"]], ["block_7", [" 17.3 Electrode and Cell Potentials \n"]], ["block_8", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_9", ["Unlike the spontaneous oxidation of copper by aqueous silver(I) ions described in section 17.2, immersing a\ncopper wire in an aqueous solution of lead(II) ions yields no reaction. The two species, Ag(aq) and Pb(aq),\nthus show a distinct difference in their redox activity towards copper: the silver ion spontaneously oxidized\ncopper, but the lead ion did not. Electrochemical cells permit this relative redox activity to be quantified by an\neasily measured property, potential. This property is more commonly called voltage when referenced in regard\nto electrical applications, and it is a measure of energy accompanying the transfer of charge. Potentials are\nmeasured in the volt unit, defined as one joule of energy per one coulomb of charge, V = J/C.\n"]], ["block_10", ["where Ecathode and Eanode are the potentials of two different half-cells functioning as specified in the subscripts.\nAs for other thermodynamic quantities, the standard cell potential, E\u00b0 cell , is a cell potential measured when\nboth half-cells are under standard-state conditions (1 M concentrations, 1 bar pressures, 298 K):\n"]], ["block_11", ["To simplify the collection and sharing of potential data for half-reactions, the scientific community has\ndesignated one particular half-cell to serve as a universal reference for cell potential measurements, assigning\nit a potential of exactly 0 V. This half-cell is the standard hydrogen electrode (SHE) and it is based on half-\nreaction below:\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["\u2022\nDescribe and relate the definitions of electrode and cell potentials\n"]], ["block_14", ["\u2022\nInterpret electrode potentials in terms of relative oxidant and reductant strengths\n"]], ["block_15", ["\u2022\nCalculate cell potentials and predict redox spontaneity using standard electrode potentials\n"]]], "page_838": [["block_0", ["The assigned potential of the SHE permits the definition of a conveniently measured potential for a single half-\ncell. The electrode potential (E X ) for a half-cell X is defined as the potential measured for a cell comprised of X\nacting as cathode and the SHE acting as anode:\n"]], ["block_1", ["A typical SHE contains an inert platinum electrode immersed in precisely 1 M aqueous Hand a stream of\nbubbling H2 gas at 1 bar pressure, all maintained at a temperature of 298 K (see Figure 17.5).\n"]], ["block_2", [{"image_0": "838_0.png", "coords": [72, 89, 540, 356]}]], ["block_3", ["When the half-cell X is under standard-state conditions, its potential is the standard electrode potential, E\u00b0 X .\nSince the definition of cell potential requires the half-cells function as cathodes, these potentials are\nsometimes called standard reduction potentials.\n"]], ["block_4", ["This approach to measuring electrode potentials is illustrated in Figure 17.6, which depicts a cell comprised of\nan SHE connected to a copper(II)/copper(0) half-cell under standard-state conditions. A voltmeter in the\nexternal circuit allows measurement of the potential difference between the two half-cells. Since the Cu half-\ncell is designated as the cathode in the definition of cell potential, it is connected to the red (positive) input of\nthe voltmeter, while the designated SHE anode is connected to the black (negative) input. These connections\ninsure that the sign of the measured potential will be consistent with the sign conventions of electrochemistry\nper the various definitions discussed above. A cell potential of +0.337 V is measured, and so\n"]], ["block_5", ["Tabulations of E\u00b0 values for other half-cells measured in a similar fashion are available as reference literature\nto permit calculations of cell potentials and the prediction of the spontaneity of redox processes.\n"]], ["block_6", [" FIGURE 17.5 \nA standard hydrogen electrode (SHE).\n"]], ["block_7", [" 17.3 \u2022 Electrode and Cell Potentials \n 825 \n"]]], "page_839": [["block_0", [" 826 \n 17 \u2022 Electrochemistry \n"]], ["block_1", [" FIGURE 17.6 \nA cell permitting experimental measurement of the standard electrode potential for the half-reaction\n"]], ["block_2", ["Table 17.1 provides a listing of standard electrode potentials for a selection of half-reactions in numerical\norder, and a more extensive alphabetical listing is given in Appendix L.\n"]], ["block_3", [" Access for free at openstax.org \n"]], ["block_4", [" TABLE 17.1 \n"]], ["block_5", [{"image_0": "839_0.png", "coords": [130, 57, 481, 348]}]], ["block_6", [" Half-Reaction \n E\u00b0 (V) \n"]], ["block_7", ["Selected Standard Reduction Potentials at 25 \u00b0C\n"]], ["block_8", ["+2.866\n"]], ["block_9", ["+1.69\n"]], ["block_10", ["+1.507\n"]], ["block_11", ["+1.498\n"]], ["block_12", ["+1.35827\n"]], ["block_13", ["+1.229\n"]], ["block_14", ["+1.20\n"]], ["block_15", ["+1.0873\n"]], ["block_16", ["+0.7996\n"]]], "page_840": [["block_0", [" TABLE 17.1 \n"]], ["block_1", [" Half-Reaction \n E\u00b0 (V) \n"]], ["block_2", [" 17.3 \u2022 Electrode and Cell Potentials \n 827 \n"]], ["block_3", ["+0.7973\n"]], ["block_4", ["+0.771\n"]], ["block_5", ["+0.558\n"]], ["block_6", ["+0.5355\n"]], ["block_7", ["+0.49\n"]], ["block_8", ["+0.34\n"]], ["block_9", ["+0.26808\n"]], ["block_10", ["+0.22233\n"]], ["block_11", ["+0.151\n"]], ["block_12", ["0.00\n"]], ["block_13", ["\u22120.1262\n"]], ["block_14", ["\u22120.1375\n"]], ["block_15", ["\u22120.257\n"]], ["block_16", ["\u22120.28\n"]], ["block_17", ["\u22120.3505\n"]], ["block_18", ["\u22120.4030\n"]], ["block_19", ["\u22120.447\n"]], ["block_20", ["\u22120.744\n"]], ["block_21", ["\u22121.185\n"]], ["block_22", ["\u22121.245\n"]], ["block_23", ["\u22120.7618\n"]], ["block_24", ["\u22121.662\n"]], ["block_25", ["\u22122.372\n"]], ["block_26", ["\u22122.71\n"]]], "page_841": [["block_0", [" 828 \n 17 \u2022 Electrochemistry \n"]], ["block_1", ["Thinking carefully about the definitions of cell and electrode potentials and the observations of spontaneous\nredox change presented thus far, a significant relation is noted. The previous section described the\nspontaneous oxidation of copper by aqueous silver(I) ions, but no observed reaction with aqueous lead(II) ions.\nResults of the calculations in Example 17.4 have just shown the spontaneous process is described by a positive\ncell potential while the nonspontaneous process exhibits a negative cell potential. And so, with regard to the\nrelative effectiveness (\u201cstrength\u201d) with which aqueous Agand Pbions oxidize Cu under standard conditions,\nthe stronger oxidant is the one exhibiting the greater standard electrode potential, E\u00b0. Since by convention\nelectrode potentials are for reduction processes, an increased value of E\u00b0 corresponds to an increased driving\nforce behind the reduction of the species (hence increased effectiveness of its action as an oxidizing agent on\nsome other species). Negative values for electrode potentials are simply a consequence of assigning a value of\n0 V to the SHE, indicating the reactant of the half-reaction is a weaker oxidant than aqueous hydrogen ions.\n"]], ["block_2", [" Calculating Standard Cell Potentials \n"]], ["block_3", ["What is the standard potential of the galvanic cell shown in Figure 17.3?\n"]], ["block_4", [" Solution \n"]], ["block_5", ["The cell in Figure 17.3 is galvanic, the spontaneous cell reaction involving oxidation of its copper anode and\nreduction of silver(I) ions at its silver cathode:\n"]], ["block_6", ["The standard cell potential computed as\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["What is the standard cell potential expected if the silver cathode half-cell in Figure 17.3 is replaced with a lead\nhalf-cell:\n?\n"]], ["block_9", [" Answer: \n\u22120. 47 V\n"]], ["block_10", [" Intrepreting Electrode and Cell Potentials \n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["EXAMPLE 17.4\n"]], ["block_13", [" TABLE 17.1 \n"]], ["block_14", [" Half-Reaction \n E\u00b0 (V) \n"]], ["block_15", ["\u22122.868\n"]], ["block_16", ["\u22122.912\n"]], ["block_17", ["\u22122.931\n"]], ["block_18", ["\u22123.04\n"]]], "page_842": [["block_0", ["Applying this logic to the numerically ordered listing of standard electrode potentials in Table 17.1 shows this\nlisting to be likewise in order of the oxidizing strength of the half-reaction\u2019s reactant species, decreasing from\nstrongest oxidant (most positive E\u00b0) to weakest oxidant (most negative E\u00b0). Predictions regarding the\nspontaneity of redox reactions under standard state conditions can then be easily made by simply comparing\nthe relative positions of their table entries. By definition, E\u00b0cell is positive when E\u00b0cathode > E\u00b0anode, and so any\nredox reaction in which the oxidant\u2019s entry is above the reductant\u2019s entry is predicted to be spontaneous.\n"]], ["block_1", ["Reconsideration of the two redox reactions in Example 17.4 provides support for this fact. The entry for the\nsilver(I)/silver(0) half-reaction is above that for the copper(II)/copper(0) half-reaction, and so the oxidation of\nCu by Agis predicted to be spontaneous (E\u00b0cathode > E\u00b0anode and so E\u00b0cell > 0). Conversely, the entry for the\nlead(II)/lead(0) half-cell is beneath that for copper(II)/copper(0), and the oxidation of Cu by Pbis\nnonspontaneous (E\u00b0cathode < E\u00b0anode and so E\u00b0cell < 0).\n"]], ["block_2", ["Recalling the chapter on thermodynamics, the spontaneities of the forward and reverse reactions of a\nreversible process show a reciprocal relationship: if a process is spontaneous in one direction, it is non-\nspontaneous in the opposite direction. As an indicator of spontaneity for redox reactions, the potential of a cell\nreaction shows a consequential relationship in its arithmetic sign. The spontaneous oxidation of copper by\nlead(II) ions is not observed,\n"]], ["block_3", ["and so the reverse reaction, the oxidation of lead by copper(II) ions, is predicted to occur spontaneously:\n"]], ["block_4", ["Note that reversing the direction of a redox reaction effectively interchanges the identities of the cathode and\nanode half-reactions, and so the cell potential is calculated from electrode potentials in the reverse subtraction\norder than that for the forward reaction. In practice, a voltmeter would report a potential of \u22120.47 V with its red\nand black inputs connected to the Pb and Cu electrodes, respectively. If the inputs were swapped, the reported\nvoltage would be +0.47 V.\n"]], ["block_5", [" Predicting Redox Spontaneity \n"]], ["block_6", ["Are aqueous iron(II) ions predicted to spontaneously oxidize elemental chromium under standard state\nconditions? Assume the half-reactions to be those available in Table 17.1.\n"]], ["block_7", [" Solution \n"]], ["block_8", ["Referring to the tabulated half-reactions, the redox reaction in question can be represented by the equations\nbelow:\n"]], ["block_9", ["The entry for the putative oxidant, Fe, appears above the entry for the reductant, Cr, and so a spontaneous\nreaction is predicted per the quick approach described above. Supporting this predication by calculating the\nstandard cell potential for this reaction gives\n"]], ["block_10", ["The positive value for the standard cell potential indicates the process is spontaneous under standard state\nconditions.\n"]], ["block_11", [" Check Your Learning \n"]], ["block_12", ["Use the data in Table 17.1 to predict the spontaneity of the oxidation of bromide ion by molecular iodine under\nstandard state conditions, supporting the prediction by calculating the standard cell potential for the reaction.\n"]], ["block_13", ["EXAMPLE 17.5\n"]], ["block_14", [" 17.3 \u2022 Electrode and Cell Potentials \n 829 \n"]]], "page_843": [["block_0", [" 830 \n 17 \u2022 Electrochemistry \n"]], ["block_1", ["Repeat for the oxidation of iodide ion by molecular bromine.\n"]], ["block_2", [" Answer: \n"]], ["block_3", [" 17.4 Potential, Free Energy, and Equilibrium \n"]], ["block_4", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_5", ["So far in this chapter, the relationship between the cell potential and reaction spontaneity has been described,\nsuggesting a link to the free energy change for the reaction (see chapter on thermodynamics). The\ninterpretation of potentials as measures of oxidant strength was presented, bringing to mind similar measures\nof acid-base strength as reflected in equilibrium constants (see the chapter on acid-base equilibria). This\nsection provides a summary of the relationships between potential and the related thermodynamic properties\n\u0394G and K.\n"]], ["block_6", [" E\u00b0 and \u0394G\u00b0 \n"]], ["block_7", ["The standard free energy change of a process, \u0394G\u00b0, was defined in a previous chapter as the maximum work\nthat could be performed by a system, wmax. In the case of a redox reaction taking place within a galvanic cell\nunder standard state conditions, essentially all the work is associated with transferring the electrons from\nreductant-to-oxidant, welec:\n"]], ["block_8", ["The work associated with transferring electrons is determined by the total amount of charge (coulombs)\ntransferred and the cell potential:\n"]], ["block_9", ["where n is the number of moles of electrons transferred, F is Faraday\u2019s constant , and E\u00b0cell is the standard cell\npotential. The relation between free energy change and standard cell potential confirms the sign conventions\nand spontaneity criteria previously discussed for both of these properties: spontaneous redox reactions\nexhibit positive potentials and negative free energy changes.\n"]], ["block_10", [" E\u00b0 and K \n"]], ["block_11", ["Combining a previously derived relation between \u0394G\u00b0 and K (see the chapter on thermodynamics) and the\nequation above relating \u0394G\u00b0 and E\u00b0cell yields the following:\n"]], ["block_12", ["This equation indicates redox reactions with large (positive) standard cell potentials will proceed far towards\ncompletion, reaching equilibrium when the majority of reactant has been converted to product. A summary of\nthe relations between E\u00b0, \u0394G\u00b0 and K is depicted in Figure 17.7, and a table correlating reaction spontaneity to\nvalues of these properties is provided in Table 17.2.\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", ["\u2022\nExplain the relations between potential, free energy change, and equilibrium constants\n"]], ["block_15", ["\u2022\nPerform calculations involving the relations between cell potentials, free energy changes, and equilibrium\n"]], ["block_16", ["\u2022\nUse the Nernst equation to determine cell potentials under nonstandard conditions\n"]]], "page_844": [["block_0", [" Equilibrium Constants, Standard Cell Potentials, and Standard Free Energy Changes \n"]], ["block_1", ["Use data from Appendix L to calculate the standard cell potential, standard free energy change, and\nequilibrium constant for the following reaction at 25 \u00b0C. Comment on the spontaneity of the forward reaction\nand the composition of an equilibrium mixture of reactants and products.\n"]], ["block_2", [" Solution \n"]], ["block_3", ["The reaction involves an oxidation-reduction reaction, so the standard cell potential can be calculated using\nthe data in Appendix L.\n"]], ["block_4", ["With n = 2, the equilibrium constant is then\n"]], ["block_5", ["EXAMPLE 17.6\n"]], ["block_6", [" FIGURE 17.7 \nGraphic depicting the relation between three important thermodynamic properties.\n"]], ["block_7", [" TABLE 17.2 \n"]], ["block_8", ["K\n\u0394G\u00b0\nE\u00b0cell\n"]], ["block_9", ["> 1\n< 0\n> 0\nReaction is spontaneous under standard conditions\n"]], ["block_10", ["< 1\n> 0\n< 0\nReaction is non-spontaneous under standard conditions\n"]], ["block_11", ["= 1\n= 0\n= 0\nReaction is at equilibrium under standard conditions\n"]], ["block_12", [{"image_0": "844_0.png", "coords": [189, 57, 423, 191]}]], ["block_13", ["Products more abundant at equilibrium\n"]], ["block_14", ["Reactants more abundant at equilibrium\n"]], ["block_15", ["Reactants and products equally abundant\n"]], ["block_16", [" 17.4 \u2022 Potential, Free Energy, and Equilibrium \n 831 \n"]]], "page_845": [["block_0", [" 832 \n 17 \u2022 Electrochemistry \n"]], ["block_1", ["This equation describes how the potential of a redox system (such as a galvanic cell) varies from its standard\nstate value, specifically, showing it to be a function of the number of electrons transferred, n, the temperature,\nT, and the reaction mixture composition as reflected in Q. A convenient form of the Nernst equation for most\nwork is one in which values for the fundamental constants (R and F) and standard temperature (298) K), along\nwith a factor converting from natural to base-10 logarithms, have been included:\n"]], ["block_2", ["The standard free energy is then\n"]], ["block_3", ["The reaction is spontaneous, as indicated by a negative free energy change and a positive cell potential. The K\nvalue is very large, indicating the reaction proceeds to near completion to yield an equilibrium mixture\ncontaining mostly products.\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["What is the standard free energy change and the equilibrium constant for the following reaction at room\ntemperature? Is the reaction spontaneous?\n"]], ["block_6", [" Answer: \n"]], ["block_7", ["Spontaneous; n = 2;\nK = 6.8\n10.\n"]], ["block_8", [" Potentials at Nonstandard Conditions: The Nernst Equation \n"]], ["block_9", ["Most of the redox processes that interest science and society do not occur under standard state conditions, and\nso the potentials of these systems under nonstandard conditions are a property worthy of attention. Having\nestablished the relationship between potential and free energy change in this section, the previously discussed\nrelation between free energy change and reaction mixture composition can be used for this purpose.\n"]], ["block_10", ["Notice the reaction quotient, Q, appears in this equation, making the free energy change dependent upon the\ncomposition of the reaction mixture. Substituting the equation relating free energy change to cell potential\nyields the Nernst equation :\n"]], ["block_11", [" Predicting Redox Spontaneity Under Nonstandard Conditions \n"]], ["block_12", ["Use the Nernst equation to predict the spontaneity of the redox reaction shown below.\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", ["EXAMPLE 17.7\n"]]], "page_846": [["block_0", [" Answer: \nn = 6; Q = 1440; Ecell = +1.97 V, spontaneous.\n"]], ["block_1", [" Solution \n"]], ["block_2", ["Collecting information from Appendix L and the problem,\n"]], ["block_3", ["Notice the negative value of the standard cell potential indicates the process is not spontaneous under\nstandard conditions. Substitution of the Nernst equation terms for the nonstandard conditions yields:\n"]], ["block_4", ["The cell potential remains negative (slightly) under the specified conditions, and so the reaction remains\nnonspontaneous.\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["For the cell schematic below, identify values for n and Q, and calculate the cell potential, Ecell.\n"]], ["block_7", ["A concentration cell is constructed by connecting two nearly identical half-cells, each based on the same half-\nreaction and using the same electrode, varying only in the concentration of one redox species. The potential of\na concentration cell, therefore, is determined only by the difference in concentration of the chosen redox\nspecies. The example problem below illustrates the use of the Nernst equation in calculations involving\nconcentration cells.\n"]], ["block_8", [" Concentration Cells \n"]], ["block_9", ["What is the cell potential of the concentration cell described by\n"]], ["block_10", [" Solution \n"]], ["block_11", ["From the information given:\n"]], ["block_12", ["Substituting into the Nernst equation,\n"]], ["block_13", ["EXAMPLE 17.8\n"]], ["block_14", [" 17.4 \u2022 Potential, Free Energy, and Equilibrium \n 833 \n"]]], "page_847": [["block_0", [" 834 \n 17 \u2022 Electrochemistry \n"]], ["block_1", [" Answer: \nEcell = 0.000 V; [Zn]cathode = [Zn]anode = 0.30 M\n"]], ["block_2", ["The positive value for cell potential indicates the overall cell reaction (see above) is spontaneous. This\nspontaneous reaction is one in which the zinc ion concentration in the cathode falls (it is reduced to elemental\nzinc) while that in the anode rises (it is produced by oxidation of the zinc anode). A greater driving force for\nzinc reduction is present in the cathode, where the zinc(II) ion concentration is greater (Ecathode > Eanode).\n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["The concentration cell above was allowed to operate until the cell reaction reached equilibrium. What are the\ncell potential and the concentrations of zinc(II) in each half-cell for the cell now?\n"]], ["block_5", [" 17.5 Batteries and Fuel Cells \n"]], ["block_6", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_7", ["There are many technological products associated with the past two centuries of electrochemistry research,\nnone more immediately obvious than the battery. A battery is a galvanic cell that has been specially designed\nand constructed in a way that best suits its intended use a source of electrical power for specific applications.\nAmong the first successful batteries was the Daniell cell, which relied on the spontaneous oxidation of zinc by\ncopper(II) ions (Figure 17.8):\n"]], ["block_8", [{"image_0": "847_0.png", "coords": [72, 407, 540, 642]}]], ["block_9", [" FIGURE 17.8 \nIllustration of a Daniell cell taken from a 1904 journal publication (left) along with a simplified\n"]], ["block_10", ["illustration depicting the electrochemistry of the cell (right). The 1904 design used a porous clay pot to both contain\none of the half-cell\u2019s content and to serve as a salt bridge to the other half-cell.\n"]], ["block_11", ["Modern batteries exist in a multitude of forms to accommodate various applications, from tiny button batteries\nthat provide the modest power needs of a wristwatch to the very large batteries used to supply backup energy\nto municipal power grids. Some batteries are designed for single-use applications and cannot be recharged\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["\u2022\nDescribe the electrochemistry associated with several common batteries\n"]], ["block_14", ["\u2022\nDistinguish the operation of a fuel cell from that of a battery\n"]]], "page_848": [["block_0", ["( primary cells ), while others are based on conveniently reversible cell reactions that allow recharging by an\nexternal power source ( secondary cells ). This section will provide a summary of the basic electrochemical\naspects of several batteries familiar to most consumers, and will introduce a related electrochemical device\ncalled a fuel cell that can offer improved performance in certain applications.\n"]], ["block_1", ["Visit this site (http://openstax.org/l/16batteries) to learn more about batteries.\n"]], ["block_2", [" Single-Use Batteries \n"]], ["block_3", ["A common primary battery is the dry cell , which uses a zinc can as both container and anode (\u201c\u2013\u201d terminal)\nand a graphite rod as the cathode (\u201c+\u201d terminal). The Zn can is filled with an electrolyte paste containing\nmanganese(IV) oxide, zinc(II) chloride, ammonium chloride, and water. A graphite rod is immersed in the\nelectrolyte paste to complete the cell. The spontaneous cell reaction involves the oxidation of zinc:\n"]], ["block_4", ["and the reduction of manganese(IV)\n"]], ["block_5", ["which together yield the cell reaction:\n"]], ["block_6", ["The voltage (cell potential) of a dry cell is approximately 1.5 V. Dry cells are available in various sizes (e.g., D, C,\nAA, AAA). All sizes of dry cells comprise the same components, and so they exhibit the same voltage, but larger\ncells contain greater amounts of the redox reactants and therefore are capable of transferring correspondingly\ngreater amounts of charge. Like other galvanic cells, dry cells may be connected in series to yield batteries with\ngreater voltage outputs, if needed.\n"]], ["block_7", ["Visit this site (http://openstax.org/l/16zinccarbon) to learn more about zinc-carbon batteries.\n"]], ["block_8", [" Alkaline batteries (Figure 17.10) were developed in the 1950s to improve on the performance of the dry cell,\n"]], ["block_9", ["LINK TO LEARNING\n"]], ["block_10", ["LINK TO LEARNING\n"]], ["block_11", [" FIGURE 17.9 \nA schematic diagram shows a typical dry cell.\n"]], ["block_12", [{"image_0": "848_0.png", "coords": [189, 408, 423, 639]}]], ["block_13", [" 17.5 \u2022 Batteries and Fuel Cells \n 835 \n"]]], "page_849": [["block_0", [" 836 \n 17 \u2022 Electrochemistry \n"]], ["block_1", ["and they were designed around the same redox couples. As their name suggests, these types of batteries use\nalkaline electrolytes, often potassium hydroxide. The reactions are\n"]], ["block_2", ["An alkaline battery can deliver about three to five times the energy of a zinc-carbon dry cell of similar size.\nAlkaline batteries are prone to leaking potassium hydroxide, so they should be removed from devices for long-\nterm storage. While some alkaline batteries are rechargeable, most are not. Attempts to recharge an alkaline\nbattery that is not rechargeable often leads to rupture of the battery and leakage of the potassium hydroxide\nelectrolyte.\n"]], ["block_3", ["Visit this site (http://openstax.org/l/16alkaline) to learn more about alkaline batteries.\n"]], ["block_4", [" Rechargeable (Secondary) Batteries \n"]], ["block_5", [" Nickel-cadmium , or NiCd, batteries (Figure 17.11) consist of a nickel-plated cathode, cadmium-plated anode,\nand a potassium hydroxide electrode. The positive and negative plates, which are prevented from shorting by\nthe separator, are rolled together and put into the case. This is a \u201cjelly-roll\u201d design and allows the NiCd cell to\ndeliver much more current than a similar-sized alkaline battery. The reactions are\n"]], ["block_6", ["When properly treated, a NiCd battery can be recharged about 1000 times. Cadmium is a toxic heavy metal so\nNiCd batteries should never be ruptured or incinerated, and they should be disposed of in accordance with\nrelevant toxic waste guidelines.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [" FIGURE 17.10 \nAlkaline batteries were designed as improved replacements for zinc-carbon (dry cell) batteries.\n"]], ["block_9", ["LINK TO LEARNING\n"]], ["block_10", [{"image_0": "849_0.png", "coords": [189, 208, 423, 440]}]]], "page_850": [["block_0", [{"image_0": "850_0.png", "coords": [72, 57, 540, 354]}]], ["block_1", [" FIGURE 17.11 \nNiCd batteries use a \u201cjelly-roll\u201d design that significantly increases the amount of current the battery\n"]], ["block_2", ["can deliver as compared to a similar-sized alkaline battery.\n"]], ["block_3", ["Visit this site (http://openstax.org/l/16NiCdrecharge) for more information about nickel cadmium rechargeable\nbatteries.\n"]], ["block_4", [" Lithium ion batteries (Figure 17.12) are among the most popular rechargeable batteries and are used in many\nportable electronic devices. The reactions are\n"]], ["block_5", ["The variable stoichiometry of the cell reaction leads to variation in cell voltages, but for typical conditions, x is\nusually no more than 0.5 and the cell voltage is approximately 3.7 V. Lithium batteries are popular because\nthey can provide a large amount current, are lighter than comparable batteries of other types, produce a nearly\nconstant voltage as they discharge, and only slowly lose their charge when stored.\n"]], ["block_6", ["LINK TO LEARNING\n"]], ["block_7", [" 17.5 \u2022 Batteries and Fuel Cells \n 837 \n"]]], "page_851": [["block_0", [" 838 \n 17 \u2022 Electrochemistry \n"]], ["block_1", [{"image_0": "851_0.png", "coords": [72, 57, 540, 232]}]], ["block_2", [" FIGURE 17.12 \nIn a lithium ion battery, charge flows as the lithium ions are transferred between the anode and\n"]], ["block_3", ["cathode.\n"]], ["block_4", ["Visit this site (http://openstax.org/l/16lithiumion) for more information about lithium ion batteries.\n"]], ["block_5", ["The lead acid battery (Figure 17.13) is the type of secondary battery commonly used in automobiles. It is\ninexpensive and capable of producing the high current required by automobile starter motors. The reactions\nfor a lead acid battery are\n"]], ["block_6", ["Each cell produces 2 V, so six cells are connected in series to produce a 12-V car battery. Lead acid batteries\nare heavy and contain a caustic liquid electrolyte, H2SO4(aq), but are often still the battery of choice because of\ntheir high current density. Since these batteries contain a significant amount of lead, they must always be\ndisposed of properly.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [" FIGURE 17.13 \nThe lead acid battery in your automobile consists of six cells connected in series to give 12 V.\n"]], ["block_9", ["LINK TO LEARNING\n"]], ["block_10", [{"image_1": "851_1.png", "coords": [130, 471, 481, 692]}]]], "page_852": [["block_0", ["Visit this site (http://openstax.org/l/16leadacid) for more information about lead acid batteries.\n"]], ["block_1", [" Fuel Cells \n"]], ["block_2", ["A fuel cell is a galvanic cell that uses traditional combustive fuels, most often hydrogen or methane, that are\ncontinuously fed into the cell along with an oxidant. (An alternative, but not very popular, name for a fuel cell is\na flow battery.) Within the cell, fuel and oxidant undergo the same redox chemistry as when they are\ncombusted, but via a catalyzed electrochemical that is significantly more efficient. For example, a typical\nhydrogen fuel cell uses graphite electrodes embedded with platinum-based catalysts to accelerate the two half-\ncell reactions:\n"]], ["block_3", ["These types of fuel cells generally produce voltages of approximately 1.2 V. Compared to an internal\ncombustion engine, the energy efficiency of a fuel cell using the same redox reaction is typically more than\ndouble (~20%\u201325% for an engine versus ~50%\u201375% for a fuel cell). Hydrogen fuel cells are commonly used on\nextended space missions, and prototypes for personal vehicles have been developed, though the technology\nremains relatively immature.\n"]], ["block_4", ["Check out this link (http://openstax.org/l/16fuelcells) to learn more about fuel cells.\n"]], ["block_5", [" FIGURE 17.14 \nIn this hydrogen fuel cell, oxygen from the air reacts with hydrogen, producing water and electricity.\n"]], ["block_6", ["LINK TO LEARNING\n"]], ["block_7", ["LINK TO LEARNING\n"]], ["block_8", [{"image_0": "852_0.png", "coords": [130, 212, 481, 475]}]], ["block_9", [" 17.5 \u2022 Batteries and Fuel Cells \n 839 \n"]]], "page_853": [["block_0", [" 840 \n 17 \u2022 Electrochemistry \n"]], ["block_1", [" 17.6 Corrosion \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", [" Corrosion is usually defined as the degradation of metals by a naturally occurring electrochemical process.\nThe formation of rust on iron, tarnish on silver, and the blue-green patina that develops on copper are all\nexamples of corrosion. The total cost of corrosion remediation in the United States is significant, with\nestimates in excess of half a trillion dollars a year.\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", ["\u2022\nDefine corrosion\n"]], ["block_6", ["\u2022\nList some of the methods used to prevent or slow corrosion\n"]], ["block_7", ["Chemistry in Everyday Life\n"]], ["block_8", [" Statue of Liberty: Changing Colors \nThe Statue of Liberty is a landmark every American recognizes. The Statue of Liberty is easily identified by\nits height, stance, and unique blue-green color (Figure 17.15). When this statue was first delivered from\nFrance, its appearance was not green. It was brown, the color of its copper \u201cskin.\u201d So how did the Statue of\nLiberty change colors? The change in appearance was a direct result of corrosion. The copper that is the\nprimary component of the statue slowly underwent oxidation from the air. The oxidation-reduction\nreactions of copper metal in the environment occur in several steps. Copper metal is oxidized to copper(I)\noxide (Cu2O), which is red, and then to copper(II) oxide, which is black\n"]], ["block_9", ["Coal, which was often high in sulfur, was burned extensively in the early part of the last century. As a result,\natmospheric sulfur trioxide, carbon dioxide, and water all reacted with the CuO\n"]], ["block_10", ["These three compounds are responsible for the characteristic blue-green patina seen on the Statue of\nLiberty (and other outdoor copper structures). Fortunately, formation of patina creates a protective layer\non the copper surface, preventing further corrosion of the underlying copper. The formation of the\nprotective layer is called passivation, a phenomenon discussed further in another chapter of this text.\n"]]], "page_854": [["block_0", ["Perhaps the most familiar example of corrosion is the formation of rust on iron. Iron will rust when it is\nexposed to oxygen and water. Rust formation involves the creation of a galvanic cell at an iron surface, as\nillustrated in Figure 17.15. The relevant redox reactions are described by the following equations:\n"]], ["block_1", ["Further reaction of the iron(II) product in humid air results in the production of an iron(III) oxide hydrate\nknown as rust:\n"]], ["block_2", ["The stoichiometry of the hydrate varies, as indicated by the use of x in the compound formula. Unlike the\npatina on copper, the formation of rust does not create a protective layer and so corrosion of the iron continues\nas the rust flakes off and exposes fresh iron to the atmosphere.\n"]], ["block_3", [" FIGURE 17.15 \n(a) The Statue of Liberty is covered with a copper skin, and was originally brown, as shown in\n"]], ["block_4", ["this painting. (b) Exposure to the elements has resulted in the formation of the blue-green patina seen today.\n"]], ["block_5", [{"image_0": "854_0.png", "coords": [130, 57, 481, 294]}]], ["block_6", [" 17.6 \u2022 Corrosion \n 841 \n"]]], "page_855": [["block_0", [" 842 \n 17 \u2022 Electrochemistry \n"]], ["block_1", ["Iron and other metals may also be protected from corrosion by galvanization , a process in which the metal to\nbe protected is coated with a layer of a more readily oxidized metal, usually zinc. When the zinc layer is intact,\nit prevents air from contacting the underlying iron and thus prevents corrosion. If the zinc layer is breached by\neither corrosion or mechanical abrasion, the iron may still be protected from corrosion by a cathodic\nprotection process, which is described in the next paragraph.\n"]], ["block_2", [" FIGURE 17.16 \nCorrosion can occur when a painted iron or steel surface is exposed to the environment by a scratch\n"]], ["block_3", ["through the paint. A galvanic cell results that may be approximated by the simplified cell schematic Fe(s) | Fe(aq)\n||O2(aq), H2O(l) | Fe(s).\n"]], ["block_4", ["One way to keep iron from corroding is to keep it painted. The layer of paint prevents the water and oxygen\nnecessary for rust formation from coming into contact with the iron. As long as the paint remains intact, the\niron is protected from corrosion.\n"]], ["block_5", ["Other strategies include alloying the iron with other metals. For example, stainless steel is an alloy of iron\ncontaining a small amount of chromium. The chromium tends to collect near the surface, where it corrodes\nand forms a passivating an oxide layer that protects the iron.\n"]], ["block_6", ["Another important way to protect metal is to make it the cathode in a galvanic cell. This is cathodic protection \nand can be used for metals other than just iron. For example, the rusting of underground iron storage tanks\nand pipes can be prevented or greatly reduced by connecting them to a more active metal such as zinc or\nmagnesium (Figure 17.17). This is also used to protect the metal parts in water heaters. The more active\nmetals (lower reduction potential) are called sacrificial anodes because as they get used up as they corrode\n(oxidize) at the anode. The metal being protected serves as the cathode for the reduction of oxygen in air, and\nso it simply serves to conduct (not react with) the electrons being transferred. When the anodes are properly\nmonitored and periodically replaced, the useful lifetime of the iron storage tank can be greatly extended.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [{"image_0": "855_0.png", "coords": [130, 57, 481, 237]}]]], "page_856": [["block_0", ["Metallic sodium, Na, and chlorine gas, Cl2, are used in numerous applications, and their industrial production\nrelies on the large-scale electrolysis of molten sodium chloride, NaCl(l). The industrial process typically uses a\nDowns cell similar to the simplified illustration shown in Figure 17.18. The reactions associated with this\nprocess are:\n"]], ["block_1", ["The cell potential for the above process is negative, indicating the reaction as written (decomposition of liquid\nNaCl) is not spontaneous. To force this reaction, a positive potential of magnitude greater than the negative cell\npotential must be applied to the cell.\n"]], ["block_2", [" FIGURE 17.17 \nCathodic protection is a useful approach to electrochemically preventing corrosion of underground\n"]], ["block_3", ["storage tanks.\n"]], ["block_4", [" 17.7 Electrolysis \n"]], ["block_5", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_6", ["Electrochemical cells in which spontaneous redox reactions take place (galvanic cells) have been the topic of\ndiscussion so far in this chapter. In these cells, electrical work is done by a redox system on its surroundings as\nelectrons produced by the redox reaction are transferred through an external circuit. This final section of the\nchapter will address an alternative scenario in which an external circuit does work on a redox system by\nimposing a voltage sufficient to drive an otherwise nonspontaneous reaction, a process known as electrolysis .\nA familiar example of electrolysis is recharging a battery, which involves use of an external power source to\ndrive the spontaneous (discharge) cell reaction in the reverse direction, restoring to some extent the\ncomposition of the half-cells and the voltage of the battery. Perhaps less familiar is the use of electrolysis in the\nrefinement of metallic ores, the manufacture of commodity chemicals, and the electroplating of metallic\ncoatings on various products (e.g., jewelry, utensils, auto parts). To illustrate the essential concepts of\nelectrolysis, a few specific processes will be considered.\n"]], ["block_7", [" The Electrolysis of Molten Sodium Chloride \n"]], ["block_8", ["\u2022\nDescribe the process of electrolysis\n"]], ["block_9", ["\u2022\nCompare the operation of electrolytic cells with that of galvanic cells\n"]], ["block_10", ["\u2022\nPerform stoichiometric calculations for electrolytic processes\n"]], ["block_11", [{"image_0": "856_0.png", "coords": [130, 57, 481, 227]}]], ["block_12", [" 17.7 \u2022 Electrolysis \n 843 \n"]]], "page_857": [["block_0", [" 844 \n 17 \u2022 Electrochemistry \n"]], ["block_1", ["process for production of sodium and chlorine, and they typically use iron cathodes and carbon anodes.\n"]], ["block_2", [" FIGURE 17.18 \nCells of this sort (a cell for the electrolysis of molten sodium chloride) are used in the Downs\n"]], ["block_3", [" The Electrolysis of Water \n"]], ["block_4", ["Water may be electrolytically decomposed in a cell similar to the one illustrated in Figure 17.19. To improve\nelectrical conductivity without introducing a different redox species, the hydrogen ion concentration of the\nwater is typically increased by addition of a strong acid. The redox processes associated with this cell are\n"]], ["block_5", ["Again, the cell potential as written is negative, indicating a nonspontaneous cell reaction that must be driven\nby imposing a cell voltage greater than +1.229 V. Keep in mind that standard electrode potentials are used to\ninform thermodynamic predictions here, though the cell is not operating under standard state conditions.\nTherefore, at best, calculated cell potentials should be considered ballpark estimates.\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [{"image_0": "857_0.png", "coords": [130, 57, 481, 308]}]]], "page_858": [["block_0", [" FIGURE 17.19 \nThe electrolysis of water produces stoichiometric amounts of oxygen gas at the anode and\n"]], ["block_1", ["hydrogen at the anode.\n"]], ["block_2", [" The Electrolysis of Aqueous Sodium Chloride \n"]], ["block_3", ["When aqueous solutions of ionic compounds are electrolyzed, the anode and cathode half-reactions may\ninvolve the electrolysis of either water species (H2O, H, OH) or solute species (the cations and anions of the\ncompound). As an example, the electrolysis of aqueous sodium chloride could involve either of these two\nanode reactions:\n"]], ["block_4", ["The standard electrode (reduction) potentials of these two half-reactions indicate water may be oxidized at a\nless negative/more positive potential (\u20131.229 V) than chloride ion (\u20131.358 V). Thermodynamics thus predicts\nthat water would be more readily oxidized, though in practice it is observed that both water and chloride ion\nare oxidized under typical conditions, producing a mixture of oxygen and chlorine gas.\n"]], ["block_5", ["Turning attention to the cathode, the possibilities for reduction are:\n"]], ["block_6", ["Comparison of these standard half-reaction potentials suggests the reduction of hydrogen ion is\n"]], ["block_7", [{"image_0": "858_0.png", "coords": [189, 57, 423, 433]}]], ["block_8", [" 17.7 \u2022 Electrolysis \n 845 \n"]]], "page_859": [["block_0", [" 846 \n 17 \u2022 Electrochemistry \n"]], ["block_1", ["Electrical current is defined as the rate of flow for any charged species. Most relevant to this discussion is the\nflow of electrons. Current is measured in a composite unit called an ampere, defined as one coulomb per\nsecond (A = 1 C/s). The charge transferred, Q, by passage of a constant current, I, over a specified time interval,\nt, is then given by the simple mathematical product\n"]], ["block_2", ["thermodynamically favored. However, in a neutral aqueous sodium chloride solution, the concentration of\nhydrogen ion is far below the standard state value of 1 M (approximately 10M), and so the observed cathode\nreaction is actually reduction of water. The net cell reaction in this case is then\n"]], ["block_3", ["This electrolysis reaction is part of the chlor-alkali process used by industry to produce chlorine and sodium\nhydroxide (lye).\n"]], ["block_4", [" Quantitative Aspects of Electrolysis \n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", ["Chemistry in Everyday Life\n"]], ["block_7", [" Electroplating \nAn important use for electrolytic cells is in electroplating. Electroplating results in a thin coating of one\nmetal on top of a conducting surface. Reasons for electroplating include making the object more corrosion\nresistant, strengthening the surface, producing a more attractive finish, or for purifying metal. The metals\ncommonly used in electroplating include cadmium, chromium, copper, gold, nickel, silver, and tin.\nCommon consumer products include silver-plated or gold-plated tableware, chrome-plated automobile\nparts, and jewelry. The silver plating of eating utensils is used here to illustrate the process. (Figure 17.20).\n"]], ["block_8", ["In the figure, the anode consists of a silver electrode, shown on the left. The cathode is located on the right\nand is the spoon, which is made from inexpensive metal. Both electrodes are immersed in a solution of\nsilver nitrate. Applying a sufficient potential results in the oxidation of the silver anode\n"]], ["block_9", ["and reduction of silver ion at the (spoon) cathode:\n"]], ["block_10", ["The net result is the transfer of silver metal from the anode to the cathode. Several experimental factors\nmust be carefully controlled to obtain high-quality silver coatings, including the exact composition of the\nelectrolyte solution, the cell voltage applied, and the rate of the electrolysis reaction (electrical current).\n"]], ["block_11", [" FIGURE 17.20 \nThis schematic shows an electrolytic cell for silver plating eating utensils.\n"]], ["block_12", [{"image_0": "859_0.png", "coords": [189, 276, 423, 462]}]]], "page_860": [["block_0", ["When electrons are transferred during a redox process, the stoichiometry of the reaction may be used to\nderive the total amount of (electronic) charge involved. For example, the generic reduction process\n"]], ["block_1", ["involves the transfer of n mole of electrons. The charge transferred is, therefore,\n"]], ["block_2", ["where F is Faraday\u2019s constant, the charge in coulombs for one mole of electrons. If the reaction takes place in\nan electrochemical cell, the current flow is conveniently measured, and it may be used to assist in\nstoichiometric calculations related to the cell reaction.\n"]], ["block_3", [" Converting Current to Moles of Electrons \n"]], ["block_4", ["In one process used for electroplating silver, a current of 10.23 A was passed through an electrolytic cell for\nexactly 1 hour. How many moles of electrons passed through the cell? What mass of silver was deposited at the\ncathode from the silver nitrate solution?\n"]], ["block_5", [" Solution \n"]], ["block_6", ["Faraday\u2019s constant can be used to convert the charge (Q) into moles of electrons (n). The charge is the current\n(I) multiplied by the time\n"]], ["block_7", ["From the problem, the solution contains AgNO3, so the reaction at the cathode involves 1 mole of electrons for\neach mole of silver\n"]], ["block_8", ["The atomic mass of silver is 107.9 g/mol, so\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["Aluminum metal can be made from aluminum(III) ions by electrolysis. What is the half-reaction at the\ncathode? What mass of aluminum metal would be recovered if a current of 25.0 A passed through the solution\nfor 15.0 minutes?\n"]], ["block_11", [" Answer: \n"]], ["block_12", [" Time Required for Deposition \n"]], ["block_13", ["In one application, a 0.010-mm layer of chromium must be deposited on a part with a total surface area of 3.3\nmfrom a solution of containing chromium(III) ions. How long would it take to deposit the layer of chromium if\nthe current was 33.46 A? The density of chromium (metal) is 7.19 g/cm.\n"]], ["block_14", [" Solution \n"]], ["block_15", ["First, compute the volume of chromium that must be produced (equal to the product of surface area and\nthickness):\n"]], ["block_16", ["EXAMPLE 17.9\n"]], ["block_17", ["EXAMPLE 17.10\n"]], ["block_18", ["0.0777 mol Al = 2.10 g Al.\n"]], ["block_19", [" 17.7 \u2022 Electrolysis \n 847 \n"]]], "page_861": [["block_0", [" 848 \n 17 \u2022 Electrochemistry \n"]], ["block_1", ["Use the computed volume and the provided density to calculate the molar amount of chromium required:\n"]], ["block_2", ["The stoichiometry of the chromium(III) reduction process requires three moles of electrons for each mole of\nchromium(0) produced, and so the total charge required is:\n"]], ["block_3", ["Finally, if this charge is passed at a rate of 33.46 C/s, the required time is:\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["What mass of zinc is required to galvanize the top of a 3.00 m\n5.50 m sheet of iron to a thickness of 0.100\n"]], ["block_6", ["mm of zinc? If the zinc comes from a solution of Zn(NO3)2 and the current is 25.5 A, how long will it take to\ngalvanize the top of the iron? The density of zinc is 7.140 g/cm.\n"]], ["block_7", [" Answer: \n11.8 kg Zn requires 382 hours.\n"]], ["block_8", [" Access for free at openstax.org \n"]]], "page_862": [["block_0", [" Key Terms \n"]], ["block_1", [" active electrode \nelectrode that participates as a\n"]], ["block_2", [" alkaline battery \nprimary battery similar to a dry\n"]], ["block_3", [" anode \nelectrode in an electrochemical cell at\n"]], ["block_4", [" battery \nsingle or series of galvanic cells designed\n"]], ["block_5", [" cathode \nelectrode in an electrochemical cell at\n"]], ["block_6", ["cathodic protection\napproach to preventing\n"]], ["block_7", [" cell notation (schematic) \nsymbolic representation\n"]], ["block_8", [" cell potential (E cell ) \ndifference in potential of the\n"]], ["block_9", [" concentration cell \ngalvanic cell comprising half-\n"]], ["block_10", [" corrosion \ndegradation of metal via a natural\n"]], ["block_11", [" dry cell \nprimary battery, also called a zinc-carbon\n"]], ["block_12", [" electrode potential (E X ) \nthe potential of a cell in\n"]], ["block_13", [" electrolysis \nprocess using electrical energy to\n"]], ["block_14", [" electrolytic cell \nelectrochemical cell in which an\n"]], ["block_15", [" Faraday\u2019s constant (F) \ncharge on 1 mol of\n"]], ["block_16", [" fuel cell \ndevices similar to galvanic cells that\n"]], ["block_17", [" galvanic (voltaic) cell \nelectrochemical cell in\n"]], ["block_18", ["cell that uses an alkaline (often potassium\nhydroxide) electrolyte; designed to be an\nimproved replacement for the dry cell, but with\nmore energy storage and less electrolyte leakage\nthan typical dry cell\n"]], ["block_19", ["corrosion of a metal object by connecting it to a\nsacrificial anode composed of a more readily\noxidized metal\n"]], ["block_20", ["reactant or product in the oxidation-reduction\nreaction of an electrochemical cell; the mass of an\nactive electrode changes during the oxidation-\nreduction reaction\n"]], ["block_21", ["which oxidation occurs\n"]], ["block_22", ["for use as a source of electrical power\n"]], ["block_23", ["which reduction occurs\n"]], ["block_24", ["of the components and reactions in an\nelectrochemical cell\n"]], ["block_25", ["cathode and anode half-cells\n"]], ["block_26", ["cells of identical composition but for the\nconcentration of one redox reactant or product\n"]], ["block_27", ["electrochemical process\n"]], ["block_28", ["battery, based on the spontaneous oxidation of\nzinc by manganese(IV)\n"]], ["block_29", ["which the half-cell of interest acts as a cathode\nwhen connected to the standard hydrogen\nelectrode\n"]], ["block_30", ["cause a nonspontaneous process to occur\n"]], ["block_31", ["external source of electrical power is used to\ndrive an otherwise nonspontaneous process\n"]], ["block_32", ["electrons; F = 96,485 C/mol e\n"]], ["block_33", ["require a continuous feed of redox reactants; also\ncalled a flow battery\n"]], ["block_34", [" galvanization \nmethod of protecting iron or similar\n"]], ["block_35", [" half cell \ncomponent of a cell that contains the\n"]], ["block_36", [" inert electrode \nelectrode that conducts electrons\n"]], ["block_37", [" lead acid battery \nrechargeable battery commonly\n"]], ["block_38", [" lithium ion battery \nwidely used rechargeable\n"]], ["block_39", [" Nernst equation \nrelating the potential of a redox\n"]], ["block_40", [" nickel-cadmium battery \nrechargeable battery\n"]], ["block_41", [" primary cell \nnonrechargeable battery, suitable for\n"]], ["block_42", [" sacrificial anode \nelectrode constructed from an\n"]], ["block_43", [" salt bridge \ntube filled with inert electrolyte\n"]], ["block_44", [" secondary cell \nbattery designed to allow\n"]], ["block_45", [" standard cell potential \nthe cell potential\n"]], ["block_46", [" standard electrode potential ( \n ) \nelectrode\n"]], ["block_47", [" standard hydrogen electrode (SHE) \nhalf-cell\n"]], ["block_48", ["which a spontaneous redox reaction takes place;\nalso called a voltaic cell\n"]], ["block_49", ["metals from corrosion by coating with a thin layer\nof more easily oxidized zinc.\n"]], ["block_50", ["redox conjugate pair (\u201ccouple\u201d) of a single\nreactant\n"]], ["block_51", ["to and from the reactants in a half-cell but that is\nnot itself oxidized or reduced\n"]], ["block_52", ["used in automobiles; it typically comprises six\ngalvanic cells based on Pb half-reactions in acidic\nsolution\n"]], ["block_53", ["battery commonly used in portable electronic\ndevices, based on lithium ion transfer between\nthe anode and cathode\n"]], ["block_54", ["system to its composition\n"]], ["block_55", ["based on Ni/Cd half-cells with applications\nsimilar to those of lithium ion batteries\n"]], ["block_56", ["single use only\n"]], ["block_57", ["easily oxidized metal, often magnesium or zinc,\nused to prevent corrosion of metal objects via\ncathodic protection\n"]], ["block_58", ["solution\n"]], ["block_59", ["recharging\n"]], ["block_60", ["when all reactants and products are in their\nstandard states (1 bar or 1 atm or gases; 1 M for\nsolutes), usually at 298.15 K\n"]], ["block_61", ["potential measured under standard conditions (1\nbar or 1 atm for gases; 1 M for solutes) usually at\n298.15 K\n"]], ["block_62", ["based on hydrogen ion production, assigned a\npotential of exactly 0 V under standard state\nconditions, used as the universal reference for\nmeasuring electrode potential\n"]], ["block_63", [" 17 \u2022 Key Terms \n 849 \n"]]], "page_863": [["block_0", [" 850 \n 17 \u2022 Key Equations \n"]], ["block_1", [" Key Equations \n"]], ["block_2", [" Summary \n"]], ["block_3", [" 17.1 Review of Redox Chemistry \n"]], ["block_4", ["Redox reactions are defined by changes in reactant\noxidation numbers, and those most relevant to\nelectrochemistry involve actual transfer of electrons.\nAqueous phase redox processes often involve water\nor its characteristic ions, Hand OH, as reactants in\naddition to the oxidant and reductant, and equations\nrepresenting these reactions can be challenging to\nbalance. The half-reaction method is a systematic\napproach to balancing such equations that involves\nseparate treatment of the oxidation and reduction\nhalf-reactions.\n"]], ["block_5", [" 17.2 Galvanic Cells \n"]], ["block_6", ["Galvanic cells are devices in which a spontaneous\nredox reaction occurs indirectly, with the oxidant\nand reductant redox couples contained in separate\nhalf-cells. Electrons are transferred from the\nreductant (in the anode half-cell) to the oxidant (in\nthe cathode half-cell) through an external circuit,\nand inert solution phase ions are transferred\nbetween half-cells, through a salt bridge, to maintain\ncharge neutrality. The construction and composition\nof a galvanic cell may be succinctly represented\nusing chemical formulas and others symbols in the\nform of a cell schematic (cell notation).\n"]], ["block_7", [" 17.3 Electrode and Cell Potentials \n"]], ["block_8", ["The property of potential, E, is the energy associated\nwith the separation/transfer of charge. In\nelectrochemistry, the potentials of cells and half-\ncells are thermodynamic quantities that reflect the\ndriving force or the spontaneity of their redox\nprocesses. The cell potential of an electrochemical\ncell is the difference in between its cathode and\nanode. To permit easy sharing of half-cell potential\ndata, the standard hydrogen electrode (SHE) is\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["Q = I\nt = n\nF\n"]], ["block_11", ["\u0394G = \u2212nFEcell\n"]], ["block_12", ["assigned a potential of exactly 0 V and used to define\na single electrode potential for any given half-cell.\nThe electrode potential of a half-cell, EX, is the cell\npotential of said half-cell acting as a cathode when\nconnected to a SHE acting as an anode. When the\nhalf-cell is operating under standard state\nconditions, its potential is the standard electrode\npotential, E\u00b0X. Standard electrode potentials reflect\nthe relative oxidizing strength of the half-reaction\u2019s\nreactant, with stronger oxidants exhibiting larger\n(more positive) E\u00b0X values. Tabulations of standard\nelectrode potentials may be used to compute\nstandard cell potentials, E\u00b0cell, for many redox\nreactions. The arithmetic sign of a cell potential\nindicates the spontaneity of the cell reaction, with\npositive values for spontaneous reactions and\nnegative values for nonspontaneous reactions\n(spontaneous in the reverse direction).\n"]], ["block_13", [" 17.4 Potential, Free Energy, and Equilibrium \n"]], ["block_14", ["Potential is a thermodynamic quantity reflecting the\nintrinsic driving force of a redox process, and it is\ndirectly related to the free energy change and\nequilibrium constant for the process. For redox\nprocesses taking place in electrochemical cells, the\nmaximum (electrical) work done by the system is\neasily computed from the cell potential and the\nreaction stoichiometry and is equal to the free\nenergy change for the process. The equilibrium\nconstant for a redox reaction is logarithmically\nrelated to the reaction\u2019s cell potential, with larger\n(more positive) potentials indicating reactions with\ngreater driving force that equilibrate when the\nreaction has proceeded far towards completion\n(large value of K). Finally, the potential of a redox\nprocess varies with the composition of the reaction\nmixture, being related to the reactions standard\npotential and the value of its reaction quotient, Q, as\n"]]], "page_864": [["block_0", ["described by the Nernst equation.\n"]], ["block_1", [" 17.5 Batteries and Fuel Cells \n"]], ["block_2", ["Galvanic cells designed specifically to function as\nelectrical power supplies are called batteries. A\nvariety of both single-use batteries (primary cells)\nand rechargeable batteries (secondary cells) are\ncommercially available to serve a variety of\napplications, with important specifications\nincluding voltage, size, and lifetime. Fuel cells,\nsometimes called flow batteries, are devices that\nharness the energy of spontaneous redox reactions\nnormally associated with combustion processes.\nLike batteries, fuel cells enable the reaction\u2019s\nelectron transfer via an external circuit, but they\nrequire continuous input of the redox reactants (fuel\nand oxidant) from an external reservoir. Fuel cells\nare typically much more efficient in converting the\nenergy released by the reaction to useful work in\ncomparison to internal combustion engines.\n"]], ["block_3", [" 17.6 Corrosion \n"]], ["block_4", ["Spontaneous oxidation of metals by natural\n"]], ["block_5", [" Exercises \n"]], ["block_6", [" 17.1 Review of Redox Chemistry \n"]], ["block_7", [" 1 . Identify each half-reaction below as either oxidation or reduction.\n"]], ["block_8", [" 2 . Identify each half-reaction below as either oxidation or reduction.\n"]], ["block_9", [" 3 . Assuming each pair of half-reactions below takes place in an acidic solution, write a balanced equation for\n"]], ["block_10", [" 4 . Balance the equations below assuming they occur in an acidic solution.\n"]], ["block_11", [" 5 . Identify the oxidant and reductant of each reaction of the previous exercise.\n"]], ["block_12", ["(a)\n(b)\n(c)\n(d)\n"]], ["block_13", ["(a)\n(b)\n(c)\n(d)\n"]], ["block_14", ["the overall reaction.\n(a)\n(b)\n(c)\n(d)\n"]], ["block_15", ["(a)\n(b)\n"]], ["block_16", ["(c)\n"]], ["block_17", ["electrochemical processes is called corrosion,\nfamiliar examples including the rusting of iron and\nthe tarnishing of silver. Corrosion process involve\nthe creation of a galvanic cell in which different sites\non the metal object function as anode and cathode,\nwith the corrosion taking place at the anodic site.\nApproaches to preventing corrosion of metals\ninclude use of a protective coating of zinc\n(galvanization) and the use of sacrificial anodes\nconnected to the metal object (cathodic protection).\n"]], ["block_18", [" 17.7 Electrolysis \n"]], ["block_19", ["Nonspontaneous redox processes may be forced to\noccur in electrochemical cells by the application of\nan appropriate potential using an external power\nsource\u2014a process known as electrolysis. Electrolysis\nis the basis for certain ore refining processes, the\nindustrial production of many chemical\ncommodities, and the electroplating of metal\ncoatings on various products. Measurement of the\ncurrent flow during electrolysis permits\nstoichiometric calculations.\n"]], ["block_20", [" 17 \u2022 Exercises \n 851 \n"]]], "page_865": [["block_0", [" 852 \n 17 \u2022 Exercises \n"]], ["block_1", [" 7 . Identify the oxidant and reductant of each reaction of the previous exercise.\n 8 . Why don\u2019t hydroxide ions appear in equations for half-reactions occurring in acidic solution?\n 9 . Why don\u2019t hydrogen ions appear in equations for half-reactions occurring in basic solution?\n 10 . Why must the charge balance in oxidation-reduction reactions?\n"]], ["block_2", [" 17.2 Galvanic Cells \n"]], ["block_3", [" 11 . Write cell schematics for the following cell reactions, using platinum as an inert electrode as needed.\n"]], ["block_4", [" 12 . Assuming the schematics below represent galvanic cells as written, identify the half-cell reactions\n"]], ["block_5", [" 13 . Write a balanced equation for the cell reaction of each cell in the previous exercise.\n 14 . Balance each reaction below, and write a cell schematic representing the reaction as it would occur in a\n"]], ["block_6", [" 15 . Identify the oxidant and reductant in each reaction of the previous exercise.\n 16 . From the information provided, use cell notation to describe the following systems:\n"]], ["block_7", [" 17 . Why is a salt bridge necessary in galvanic cells like the one in Figure 17.3?\n 18 . An active (metal) electrode was found to gain mass as the oxidation-reduction reaction was allowed to\n"]], ["block_8", [" 19 . An active (metal) electrode was found to lose mass as the oxidation-reduction reaction was allowed to\n"]], ["block_9", [" 20 . The masses of three electrodes (A, B, and C), each from three different galvanic cells, were measured\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [" 6 . Balance the equations below assuming they occur in a basic solution.\n"]], ["block_12", ["(a)\n(b)\n(c)\n(d)\n"]], ["block_13", ["(a)\n(b)\n(c)\n(d)\n"]], ["block_14", ["occurring in each.\n(a)\n"]], ["block_15", ["(b)\n"]], ["block_16", ["galvanic cell.\n(a)\n(b)\n(c)\n(d)\n"]], ["block_17", ["(a) In one half-cell, a solution of Pt(NO3)2 forms Pt metal, while in the other half-cell, Cu metal goes into a\nCu(NO3)2 solution with all solute concentrations 1 M.\n(b) The cathode consists of a gold electrode in a 0.55 M Au(NO3)3 solution and the anode is a magnesium\nelectrode in 0.75 M Mg(NO3)2 solution.\n(c) One half-cell consists of a silver electrode in a 1 M AgNO3 solution, and in the other half-cell, a copper\nelectrode in 1 M Cu(NO3)2 is oxidized.\n"]], ["block_18", ["proceed. Was the electrode an anode or a cathode? Explain.\n"]], ["block_19", ["proceed. Was the electrode an anode or a cathode? Explain.\n"]], ["block_20", ["before and after the cells were allowed to pass current for a while. The mass of electrode A increased, that\nof electrode B was unchanged, and that of electrode C decreased. Identify each electrode as active or inert,\nand note (if possible) whether it functioned as anode or cathode.\n"]]], "page_866": [["block_0", [" 17.3 Electrode and Cell Potentials \n"]], ["block_1", [" 21 . Calculate the standard cell potential for each reaction below, and note whether the reaction is\n"]], ["block_2", [" 22 . Calculate the standard cell potential for each reaction below, and note whether the reaction is\n"]], ["block_3", [" 23 . Write the balanced cell reaction for the cell schematic below, calculate the standard cell potential, and\n"]], ["block_4", [" 24 . Determine the cell reaction and standard cell potential at 25 \u00b0C for a cell made from a cathode half-cell\n"]], ["block_5", [" 25 . Determine the cell reaction and standard cell potential at 25 \u00b0C for a cell made from an anode half-cell\n"]], ["block_6", [" 26 . Write the balanced cell reaction for the cell schematic below, calculate the standard cell potential, and\n"]], ["block_7", [" 17.4 Potential, Free Energy, and Equilibrium \n"]], ["block_8", [" 27 . For each pair of standard cell potential and electron stoichiometry values below, calculate a\n"]], ["block_9", [" 28 . For each pair of standard free energy change and electron stoichiometry values below, calculate a\n"]], ["block_10", [" 29 . Determine the standard cell potential and the cell potential under the stated conditions for the\n"]], ["block_11", [" 30 . Determine \u0394G and \u0394G\u00b0 for each of the reactions in the previous problem.\n 31 . Use the data in Appendix L to calculate equilibrium constants for the following reactions. Assume 298.15\n"]], ["block_12", ["spontaneous under standard state conditions.\n(a)\n(b)\n(c)\n(d)\n"]], ["block_13", ["spontaneous under standard state conditions.\n(a)\n(b)\n(c)\n(d)\n"]], ["block_14", ["note whether the reaction is spontaneous under standard state conditions.\n"]], ["block_15", ["consisting of a silver electrode in 1 M silver nitrate solution and an anode half-cell consisting of a zinc\nelectrode in 1 M zinc nitrate. Is the reaction spontaneous at standard conditions?\n"]], ["block_16", ["containing a cadmium electrode in 1 M cadmium nitrate and a cathode half-cell consisting of an\naluminum electrode in 1 M aluminum nitrate solution. Is the reaction spontaneous at standard\nconditions?\n"]], ["block_17", ["note whether the reaction is spontaneous under standard state conditions.\n"]], ["block_18", ["corresponding standard free energy change (kJ).\n(a) 0.000 V, n = 2\n(b) +0.434 V, n = 2\n(c) \u22122.439 V, n = 1\n"]], ["block_19", ["corresponding standard cell potential.\n(a) 12 kJ/mol, n = 3\n(b) \u221245 kJ/mol, n = 1\n"]], ["block_20", ["electrochemical reactions described here. State whether each is spontaneous or nonspontaneous under\neach set of conditions at 298.15 K.\n(a)\n(b) The cell made from an anode half-cell consisting of an aluminum electrode in 0.015 M aluminum\nnitrate solution and a cathode half-cell consisting of a nickel electrode in 0.25 M nickel(II) nitrate solution.\n(c) The cell comprised of a half-cell in which aqueous bromine (1.0 M) is being oxidized to bromide ion\n(0.11 M) and a half-cell in which Al(0.023 M) is being reduced to aluminum metal.\n"]], ["block_21", ["K if no temperature is given.\n(a)\n(b)\n(c)\n(d)\n"]], ["block_22", [" 17 \u2022 Exercises \n 853 \n"]]], "page_867": [["block_0", [" 854 \n 17 \u2022 Exercises \n"]], ["block_1", [" 17.5 Batteries and Fuel Cells \n"]], ["block_2", [" 32 . Consider a battery made from one half-cell that consists of a copper electrode in 1 M CuSO4 solution and\n"]], ["block_3", [" 33 . Consider a battery with the overall reaction:\n"]], ["block_4", [" 34 . Why do batteries go dead, but fuel cells do not?\n 35 . Use the Nernst equation to explain the drop in voltage observed for some batteries as they discharge.\n 36 . Using the information thus far in this chapter, explain why battery-powered electronics perform poorly in\n"]], ["block_5", [" 17.6 Corrosion \n"]], ["block_6", [" 37 . Which member of each pair of metals is more likely to corrode (oxidize)?\n"]], ["block_7", [" 38 . Consider the following metals: Ag, Au, Mg, Ni, and Zn. Which of these metals could be used as a sacrificial\n"]], ["block_8", [" 39 . Aluminum\nis more easily oxidized than iron\nand yet when\n"]], ["block_9", [" 40 . If a sample of iron and a sample of zinc come into contact, the zinc corrodes but the iron does not. If a\n"]], ["block_10", [" 41 . Suppose you have three different metals, A, B, and C. When metals A and B come into contact, B corrodes\n"]], ["block_11", [" 42 . Why would a sacrificial anode made of lithium metal be a bad choice\n"]], ["block_12", [" 17.7 Electrolysis \n"]], ["block_13", [" 43 . If a 2.5 A current flows through a circuit for 35 minutes, how many coulombs of charge moved through the\n"]], ["block_14", [" 44 . For the scenario in the previous question, how many electrons moved through the circuit?\n 45 . Write the half-reactions and cell reaction occurring during electrolysis of each molten salt below.\n"]], ["block_15", [" 46 . What mass of each product is produced in each of the electrolytic cells of the previous problem if a total\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["another half-cell that consists of a lead electrode in 1 M Pb(NO3)2 solution.\n(a) What is the standard cell potential for the battery?\n(b) What are the reactions at the anode, cathode, and the overall reaction?\n(c) Most devices designed to use dry-cell batteries can operate between 1.0 and 1.5 V. Could this cell be\nused to make a battery that could replace a dry-cell battery? Why or why not.\n(d) Suppose sulfuric acid is added to the half-cell with the lead electrode and some PbSO4(s) forms. Would\nthe cell potential increase, decrease, or remain the same?\n"]], ["block_18", ["(a) What is the reaction at the anode and cathode?\n(b) A battery is \u201cdead\u201d when its cell potential is zero. What is the value of Q when this battery is dead?\n(c) If a particular dead battery was found to have [Cu] = 0.11 M, what was the concentration of silver ion?\n"]], ["block_19", ["low temperatures.\n"]], ["block_20", ["(a) Mg or Ca\n(b) Au or Hg\n(c) Fe or Zn\n(d) Ag or Pt\n"]], ["block_21", ["anode in the cathodic protection of an underground steel storage tank? Steel is an alloy composed mostly\nof iron, so use \u22120.447 V as the standard reduction potential for steel.\n"]], ["block_22", ["both are exposed to the environment, untreated aluminum has very good corrosion resistance while the\ncorrosion resistance of untreated iron is poor. What might explain this observation?\n"]], ["block_23", ["sample of iron comes into contact with a sample of copper, the iron corrodes but the copper does not.\nExplain this phenomenon.\n"]], ["block_24", ["and A does not corrode. When metals A and C come into contact, A corrodes and C does not corrode.\nBased on this information, which metal corrodes and which metal does not corrode when B and C come\ninto contact?\n"]], ["block_25", ["circuit?\n"]], ["block_26", ["(a) CaCl2\n(b) LiH\n(c) AlCl3\n(d) CrBr3\n"]], ["block_27", ["charge of 3.33\n10C passes through each cell?\n"]]], "page_868": [["block_0", [" 47 . How long would it take to reduce 1 mole of each of the following ions using the current indicated?\n"]], ["block_1", [" 48 . A current of 2.345 A passes through the cell shown in Figure 17.19 for 45 minutes. What is the volume of\n"]], ["block_2", [" 49 . An irregularly shaped metal part made from a particular alloy was galvanized with zinc using a Zn(NO3)2\n"]], ["block_3", ["(a) Al, 1.234 A\n(b) Ca, 22.2 A\n(c) Cr, 37.45 A\n(d) Au, 3.57 A\n"]], ["block_4", ["the hydrogen collected at room temperature if the pressure is exactly 1 atm? (Hint: Is hydrogen the only\ngas present above the water?)\n"]], ["block_5", ["solution. When a current of 2.599 A was used, it took exactly 1 hour to deposit a 0.01123-mm layer of zinc\non the part. What was the total surface area of the part? The density of zinc is 7.140 g/cm.\n"]], ["block_6", [" 17 \u2022 Exercises \n 855 \n"]]], "page_869": [["block_0", [" 856 \n 17 \u2022 Exercises \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_870": [["block_0", ["CHAPTER 18\nRepresentative Metals, Metalloids, and\nNonmetals\n"]], ["block_1", [{"image_0": "870_0.png", "coords": [72, 131, 622, 292]}]], ["block_2", [" Figure 18.1 \nPurity is extremely important when preparing silicon wafers. Technicians in a cleanroom prepare\n"]], ["block_3", ["silicon without impurities (left). The CEO of VLSI Research, Don Hutcheson, shows off a pure silicon wafer (center). A\nsilicon wafer covered in Pentium chips is an enlarged version of the silicon wafers found in many electronics used\ntoday (right). (credit middle: modification of work by \u201cIntel Free Press\u201d/Flickr; credit right: modification of work by\nNaotake Murayama)\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 18.1 Periodicity \n 18.2 Occurrence and Preparation of the Representative Metals \n 18.3 Structure and General Properties of the Metalloids \n 18.4 Structure and General Properties of the Nonmetals \n 18.5 Occurrence, Preparation, and Compounds of Hydrogen \n 18.6 Occurrence, Preparation, and Properties of Carbonates \n 18.7 Occurrence, Preparation, and Properties of Nitrogen \n 18.8 Occurrence, Preparation, and Properties of Phosphorus \n 18.9 Occurrence, Preparation, and Compounds of Oxygen \n 18.10 Occurrence, Preparation, and Properties of Sulfur \n 18.11 Occurrence, Preparation, and Properties of Halogens \n 18.12 Occurrence, Preparation, and Properties of the Noble Gases \n"]], ["block_6", [" INTRODUCTION \n"]], ["block_7", ["was a periodic relationship between the properties of the elements. Chemists, who have an understanding of\nthe variations of these properties, have been able to use this knowledge to solve a wide variety of technical\nchallenges. For example, silicon and other semiconductors form the backbone of modern electronics because\nof our ability to fine-tune the electrical properties of these materials. This chapter explores important\nproperties of representative metals, metalloids, and nonmetals in the periodic table.\n"]], ["block_8", ["The development of the periodic table in the mid-1800s came from observations that there\n"]]], "page_871": [["block_0", [" 858 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", [" 18.1 Periodicity \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["We begin this section by examining the behaviors of representative metals in relation to their positions in the\nperiodic table. The primary focus of this section will be the application of periodicity to the representative\nmetals.\n"]], ["block_4", ["It is possible to divide elements into groups according to their electron configurations. The representative \n elements are elements where the s and p orbitals are filling. The transition elements are elements where the d\norbitals (groups 3\u201311 on the periodic table) are filling, and the inner transition metals are the elements where\nthe f orbitals are filling. The d orbitals fill with the elements in group 11; therefore, the elements in group 12\nqualify as representative elements because the last electron enters an s orbital. Metals among the\nrepresentative elements are the representative metals . Metallic character results from an element\u2019s ability to\nlose its outer valence electrons and results in high thermal and electrical conductivity, among other physical\nand chemical properties. There are 20 nonradioactive representative metals in groups 1, 2, 3, 12, 13, 14, and\n15 of the periodic table (the elements shaded in yellow in Figure 18.2). The radioactive elements copernicium,\nflerovium, polonium, and livermorium are also metals but are beyond the scope of this chapter.\n"]], ["block_5", ["In addition to the representative metals, some of the representative elements are metalloids. A metalloid is an\nelement that has properties that are between those of metals and nonmetals; these elements are typically\nsemiconductors.\n"]], ["block_6", ["The remaining representative elements are nonmetals. Unlike metals , which typically form cations and ionic\ncompounds (containing ionic bonds), nonmetals tend to form anions or molecular compounds. In general, the\ncombination of a metal and a nonmetal produces a salt. A salt is an ionic compound consisting of cations and\nanions.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", ["\u2022\nClassify elements\n"]], ["block_9", ["\u2022\nMake predictions about the periodicity properties of the representative elements\n"]]], "page_872": [["block_0", [{"image_0": "872_0.png", "coords": [72, 57, 540, 441]}]], ["block_1", [" FIGURE 18.2 \nThe location of the representative metals is shown in the periodic table. Nonmetals are shown in\n"]], ["block_2", ["green, metalloids in purple, and the transition metals and inner transition metals in blue.\n"]], ["block_3", ["Most of the representative metals do not occur naturally in an uncombined state because they readily react\nwith water and oxygen in the air. However, it is possible to isolate elemental beryllium, magnesium, zinc,\ncadmium, mercury, aluminum, tin, and lead from their naturally occurring minerals and use them because\nthey react very slowly with air. Part of the reason why these elements react slowly is that these elements react\nwith air to form a protective coating. The formation of this protective coating is passivation . The coating is a\nnonreactive film of oxide or some other compound. Elemental magnesium, aluminum, zinc, and tin are\nimportant in the fabrication of many familiar items, including wire, cookware, foil, and many household and\npersonal objects. Although beryllium, cadmium, mercury, and lead are readily available, there are limitations\nin their use because of their toxicity.\n"]], ["block_4", [" Group 1: The Alkali Metals \n"]], ["block_5", ["The alkali metals lithium, sodium, potassium, rubidium, cesium, and francium constitute group 1 of the\nperiodic table. Although hydrogen is in group 1 (and also in group 17), it is a nonmetal and deserves separate\nconsideration later in this chapter. The name alkali metal is in reference to the fact that these metals and their\noxides react with water to form very basic (alkaline) solutions.\n"]], ["block_6", ["The properties of the alkali metals are similar to each other as expected for elements in the same family. The\nalkali metals have the largest atomic radii and the lowest first ionization energy in their periods. This\ncombination makes it very easy to remove the single electron in the outermost (valence) shell of each. The easy\nloss of this valence electron means that these metals readily form stable cations with a charge of 1+. Their\n"]], ["block_7", [" 18.1 \u2022 Periodicity \n 859 \n"]]], "page_873": [["block_0", [" 860 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["reactivity increases with increasing atomic number due to the ease of losing the lone valence electron\n(decreasing ionization energy). Since oxidation is so easy, the reverse, reduction, is difficult, which explains\nwhy it is hard to isolate the elements. The solid alkali metals are very soft; lithium, shown in Figure 18.3, has\nthe lowest density of any metal (0.5 g/cm).\n"]], ["block_2", ["The alkali metals all react vigorously with water to form hydrogen gas and a basic solution of the metal\nhydroxide. This means they are easier to oxidize than is hydrogen. As an example, the reaction of lithium with\nwater is:\n"]], ["block_3", ["Alkali metals react directly with all the nonmetals (except the noble gases) to yield binary ionic compounds\ncontaining 1+ metal ions. These metals are so reactive that it is necessary to avoid contact with both moisture\nand oxygen in the air. Therefore, they are stored in sealed containers under mineral oil, as shown in Figure\n18.4, to prevent contact with air and moisture. The pure metals never exist free (uncombined) in nature due to\ntheir high reactivity. In addition, this high reactivity makes it necessary to prepare the metals by electrolysis of\nalkali metal compounds.\n"]], ["block_4", [" FIGURE 18.4 \nTo prevent contact with air and water, potassium for laboratory use comes as sticks or beads stored\n"]], ["block_5", ["under kerosene or mineral oil, or in sealed containers. (credit: http://images-of-elements.com/potassium.php)\n"]], ["block_6", ["Unlike many other metals, the reactivity and softness of the alkali metals make these metals unsuitable for\nstructural applications. However, there are applications where the reactivity of the alkali metals is an\nadvantage. For example, the production of metals such as titanium and zirconium relies, in part, on the ability\nof sodium to reduce compounds of these metals. The manufacture of many organic compounds, including\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [" FIGURE 18.3 \nLithium floats in paraffin oil because its density is less than the density of paraffin oil.\n"]], ["block_9", [{"image_0": "873_0.png", "coords": [189, 175, 423, 305]}]], ["block_10", [{"image_1": "873_1.png", "coords": [189, 408, 423, 642]}]]], "page_874": [["block_0", ["certain dyes, drugs, and perfumes, utilizes reduction by lithium or sodium.\n"]], ["block_1", ["Sodium and its compounds impart a bright yellow color to a flame, as seen in Figure 18.5. Passing an electrical\ndischarge through sodium vapor also produces this color. In both cases, this is an example of an emission\nspectrum as discussed in the chapter on electronic structure. Streetlights sometime employ sodium vapor\nlights because the sodium vapor penetrates fog better than most other light. This is because the fog does not\nscatter yellow light as much as it scatters white light. The other alkali metals and their salts also impart color to\na flame. Lithium creates a bright, crimson color, whereas the others create a pale, violet color.\n"]], ["block_2", [" FIGURE 18.5 \nDipping a wire into a solution of a sodium salt and then heating the wire causes emission of a bright\n"]], ["block_3", ["yellow light, characteristic of sodium.\n"]], ["block_4", ["This video (http://openstax.org/l/16alkalih2o) demonstrates the reactions of the alkali metals with water.\n"]], ["block_5", [" Group 2: The Alkaline Earth Metals \n"]], ["block_6", ["The alkaline earth metals (beryllium, magnesium, calcium, strontium, barium, and radium) constitute group\n2 of the periodic table. The name alkaline metal comes from the fact that the oxides of the heavier members of\nthe group react with water to form alkaline solutions. The nuclear charge increases when going from group 1\nto group 2. Because of this charge increase, the atoms of the alkaline earth metals are smaller and have higher\nfirst ionization energies than the alkali metals within the same period. The higher ionization energy makes the\nalkaline earth metals less reactive than the alkali metals; however, they are still very reactive elements. Their\nreactivity increases, as expected, with increasing size and decreasing ionization energy. In chemical reactions,\nthese metals readily lose both valence electrons to form compounds in which they exhibit an oxidation state of\n2+. Due to their high reactivity, it is common to produce the alkaline earth metals, like the alkali metals, by\n"]], ["block_7", ["LINK TO LEARNING\n"]], ["block_8", [{"image_0": "874_0.png", "coords": [247, 158, 364, 505]}]], ["block_9", [" 18.1 \u2022 Periodicity \n 861 \n"]]], "page_875": [["block_0", [" 862 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["electrolysis. Even though the ionization energies are low, the two metals with the highest ionization energies\n(beryllium and magnesium) do form compounds that exhibit some covalent characters. Like the alkali metals,\nthe heavier alkaline earth metals impart color to a flame. As in the case of the alkali metals, this is part of the\nemission spectrum of these elements. Calcium and strontium produce shades of red, whereas barium\nproduces a green color.\n"]], ["block_2", ["Magnesium is a silver-white metal that is malleable and ductile at high temperatures. Passivation decreases\nthe reactivity of magnesium metal. Upon exposure to air, a tightly adhering layer of magnesium oxycarbonate\nforms on the surface of the metal and inhibits further reaction. (The carbonate comes from the reaction of\ncarbon dioxide in the atmosphere.) Magnesium is the lightest of the widely used structural metals, which is\nwhy most magnesium production is for lightweight alloys.\n"]], ["block_3", ["Magnesium (shown in Figure 18.6), calcium, strontium, and barium react with water and air. At room\ntemperature, barium shows the most vigorous reaction. The products of the reaction with water are hydrogen\nand the metal hydroxide. The formation of hydrogen gas indicates that the heavier alkaline earth metals are\nbetter reducing agents (more easily oxidized) than is hydrogen. As expected, these metals react with both acids\nand nonmetals to form ionic compounds. Unlike most salts of the alkali metals, many of the common salts of\nthe alkaline earth metals are insoluble in water because of the high lattice energies of these compounds,\ncontaining a divalent metal ion.\n"]], ["block_4", [" FIGURE 18.6 \nFrom left to right: Mg(s), warm water at pH 7, and the resulting solution with a pH greater than 7, as\n"]], ["block_5", ["indicated by the pink color of the phenolphthalein indicator. (credit: modification of work by Sahar Atwa)\n"]], ["block_6", ["The potent reducing power of hot magnesium is useful in preparing some metals from their oxides. Indeed,\nmagnesium\u2019s affinity for oxygen is so great that burning magnesium reacts with carbon dioxide, producing\nelemental carbon:\n"]], ["block_7", ["For this reason, a CO2 fire extinguisher will not extinguish a magnesium fire. Additionally, the brilliant white\nlight emitted by burning magnesium makes it useful in flares and fireworks.\n"]], ["block_8", [" Group 12 \n"]], ["block_9", ["The elements in group 12 are transition elements; however, the last electron added is not a d electron, but an s\nelectron. Since the last electron added is an s electron, these elements qualify as representative metals, or\npost-transition metals. The group 12 elements behave more like the alkaline earth metals than transition\nmetals. Group 12 contains the four elements zinc, cadmium, mercury, and copernicium. Each of these\nelements has two electrons in its outer shell (ns). When atoms of these metals form cations with a charge of\n2+, where the two outer electrons are lost, they have pseudo-noble gas electron configurations. Mercury is\nsometimes an exception because it also exhibits an oxidation state of 1+ in compounds that contain a diatomic\n"]], ["block_10", ["Zinc is the most reactive in group 12, and mercury is the least reactive. (This is the reverse of the reactivity\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["ion. In their elemental forms and in compounds, cadmium and mercury are both toxic.\n"]], ["block_13", [{"image_0": "875_0.png", "coords": [189, 290, 423, 466]}]]], "page_876": [["block_0", ["trend of the metals of groups 1 and 2, in which reactivity increases down a group. The increase in reactivity\nwith increasing atomic number only occurs for the metals in groups 1 and 2.) The decreasing reactivity is due\nto the formation of ions with a pseudo-noble gas configuration and to other factors that are beyond the scope of\nthis discussion. The chemical behaviors of zinc and cadmium are quite similar to each other but differ from\nthat of mercury.\n"]], ["block_1", ["Zinc and cadmium have lower reduction potentials than hydrogen, and, like the alkali metals and alkaline\nearth metals, they will produce hydrogen gas when they react with acids. The reaction of zinc with\nhydrochloric acid, shown in Figure 18.7, is:\n"]], ["block_2", [" FIGURE 18.7 \nZinc is an active metal. It dissolves in hydrochloric acid, forming a solution of colorless Znions, Cl\n"]], ["block_3", ["ions, and hydrogen gas.\n"]], ["block_4", ["Zinc is a silvery metal that quickly tarnishes to a blue-gray appearance. This change in color is due to an\nadherent coating of a basic carbonate, Zn2(OH)2CO3, which passivates the metal to inhibit further corrosion.\nDry cell and alkaline batteries contain a zinc anode. Brass (Cu and Zn) and some bronze (Cu, Sn, and\nsometimes Zn) are important zinc alloys. About half of zinc production serves to protect iron and other metals\nfrom corrosion. This protection may take the form of a sacrificial anode (also known as a galvanic anode, which\nis a means of providing cathodic protection for various metals) or as a thin coating on the protected metal.\nGalvanized steel is steel with a protective coating of zinc.\n"]], ["block_5", ["Chemistry in Everyday Life\n"]], ["block_6", [" Sacrificial Anodes \nA sacrificial anode, or galvanic anode, is a means of providing cathodic protection of various metals.\nCathodic protection refers to the prevention of corrosion by converting the corroding metal into a cathode.\nAs a cathode, the metal resists corrosion, which is an oxidation process. Corrosion occurs at the sacrificial\nanode instead of at the cathode.\n"]], ["block_7", ["The construction of such a system begins with the attachment of a more active metal (more negative\nreduction potential) to the metal needing protection. Attachment may be direct or via a wire. To complete\nthe circuit, a salt bridge is necessary. This salt bridge is often seawater or ground water. Once the circuit is\ncomplete, oxidation (corrosion) occurs at the anode and not the cathode.\n"]], ["block_8", ["The commonly used sacrificial anodes are magnesium, aluminum, and zinc. Magnesium has the most\nnegative reduction potential of the three and serves best when the salt bridge is less efficient due to a low\nelectrolyte concentration such as in freshwater. Zinc and aluminum work better in saltwater than does\nmagnesium. Aluminum is lighter than zinc and has a higher capacity; however, an oxide coating may\npassivate the aluminum. In special cases, other materials are useful. For example, iron will protect copper.\n"]], ["block_9", [{"image_0": "876_0.png", "coords": [247, 190, 364, 353]}]], ["block_10", [" 18.1 \u2022 Periodicity \n 863 \n"]]], "page_877": [["block_0", [" 864 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["Mercury is very different from zinc and cadmium. Mercury is the only metal that is liquid at 25 \u00b0C. Many\nmetals dissolve in mercury, forming solutions called amalgams (see the feature on Amalgams), which are\nalloys of mercury with one or more other metals. Mercury, shown in Figure 18.8, is a nonreactive element that\nis more difficult to oxidize than hydrogen. Thus, it does not displace hydrogen from acids; however, it will react\nwith strong oxidizing acids, such as nitric acid:\n"]], ["block_2", ["The clear NO initially formed quickly undergoes further oxidation to the reddish brown NO2.\n"]], ["block_3", ["Most mercury compounds decompose when heated. Most mercury compounds contain mercury with a 2+-\noxidation state. When there is a large excess of mercury, it is possible to form compounds containing the\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", ["Chemistry in Everyday Life\n"]], ["block_6", [" Amalgams \nAn amalgam is an alloy of mercury with one or more other metals. This is similar to considering steel to be\nan alloy of iron with other metals. Most metals will form an amalgam with mercury, with the main\nexceptions being iron, platinum, tungsten, and tantalum.\n"]], ["block_7", ["Due to toxicity issues with mercury, there has been a significant decrease in the use of amalgams.\nHistorically, amalgams were important in electrolytic cells and in the extraction of gold. Amalgams of the\nalkali metals still find use because they are strong reducing agents and easier to handle than the pure alkali\nmetals.\n"]], ["block_8", ["Prospectors had a problem when they found finely divided gold. They learned that adding mercury to their\npans collected the gold into the mercury to form an amalgam for easier collection. Unfortunately, losses of\nsmall amounts of mercury over the years left many streams in California polluted with mercury.\n"]], ["block_9", ["Dentists use amalgams containing silver and other metals to fill cavities. There are several reasons to use\nan amalgam including low cost, ease of manipulation, and longevity compared to alternate materials.\nDental amalgams are approximately 50% mercury by weight, which, in recent years, has become a concern\ndue to the toxicity of mercury.\n"]], ["block_10", ["After reviewing the best available data, the Food and Drug Administration (FDA) considers amalgam-based\nfillings to be safe for adults and children over six years of age. Even with multiple fillings, the mercury\nlevels in the patients remain far below the lowest levels associated with harm. Clinical studies have found\nno link between dental amalgams and health problems. Health issues may not be the same in cases of\n"]], ["block_11", [" FIGURE 18.8 \nFrom left to right: Hg(l), Hg + concentrated HCl, Hg + concentrated HNO3. (credit: Sahar Atwa)\n"]], ["block_12", ["ion. All mercury compounds are toxic, and it is necessary to exercise great care in their synthesis.\n"]], ["block_13", [{"image_0": "877_0.png", "coords": [189, 179, 423, 355]}]]], "page_878": [["block_0", [" Group 13 \n"]], ["block_1", ["Group 13 contains the metalloid boron and the metals aluminum, gallium, indium, and thallium. The lightest\nelement, boron, is semiconducting, and its binary compounds tend to be covalent and not ionic. The\nremaining elements of the group are metals, but their oxides and hydroxides change characters. The oxides\nand hydroxides of aluminum and gallium exhibit both acidic and basic behaviors. A substance, such as these\ntwo, that will react with both acids and bases is amphoteric. This characteristic illustrates the combination of\nnonmetallic and metallic behaviors of these two elements. Indium and thallium oxides and hydroxides exhibit\nonly basic behavior, in accordance with the clearly metallic character of these two elements. The melting point\nof gallium is unusually low (about 30 \u00b0C) and will melt in your hand.\n"]], ["block_2", ["Aluminum is amphoteric because it will react with both acids and bases. A typical reaction with an acid is:\n"]], ["block_3", ["The products of the reaction of aluminum with a base depend upon the reaction conditions, with the following\nbeing one possibility:\n"]], ["block_4", ["With both acids and bases, the reaction with aluminum generates hydrogen gas.\n"]], ["block_5", ["The group 13 elements have a valence shell electron configuration of nsnp. Aluminum normally uses all of\nits valence electrons when it reacts, giving compounds in which it has an oxidation state of 3+. Although many\nof these compounds are covalent, others, such as AlF3 and Al2(SO4)3, are ionic. Aqueous solutions of aluminum\n"]], ["block_6", ["salts contain the cation\nabbreviated as Al(aq). Gallium, indium, and thallium also form ionic\n"]], ["block_7", ["compounds containing Mions. These three elements exhibit not only the expected oxidation state of 3+ from\nthe three valence electrons but also an oxidation state (in this case, 1+) that is two below the expected value.\nThis phenomenon, the inert pair effect, refers to the formation of a stable ion with an oxidation state two lower\nthan expected for the group. The pair of electrons is the valence s orbital for those elements. In general, the\ninert pair effect is important for the lower p-block elements. In an aqueous solution, the Tl(aq) ion is more\nstable than is Tl(aq). In general, these metals will react with air and water to form 3+ ions; however, thallium\nreacts to give thallium(I) derivatives. The metals of group 13 all react directly with nonmetals such as sulfur,\nphosphorus, and the halogens, forming binary compounds.\n"]], ["block_8", ["The metals of group 13 (Al, Ga, In, and Tl) are all reactive. However, passivation occurs as a tough, hard, thin\nfilm of the metal oxide forms upon exposure to air. Disruption of this film may counter the passivation,\nallowing the metal to react. One way to disrupt the film is to expose the passivated metal to mercury. Some of\nthe metal dissolves in the mercury to form an amalgam, which sheds the protective oxide layer to expose the\nmetal to further reaction. The formation of an amalgam allows the metal to react with air and water.\n"]], ["block_9", ["Although easily oxidized, the passivation of aluminum makes it very useful as a strong, lightweight building\nmaterial. Because of the formation of an amalgam, mercury is corrosive to structural materials made of\naluminum. This video (http://openstax.org/l/16aluminumhg) demonstrates how the integrity of an aluminum\nbeam can be destroyed by the addition of a small amount of elemental mercury.\n"]], ["block_10", ["The most important uses of aluminum are in the construction and transportation industries, and in the\nmanufacture of aluminum cans and aluminum foil. These uses depend on the lightness, toughness, and\nstrength of the metal, as well as its resistance to corrosion. Because aluminum is an excellent conductor of\nheat and resists corrosion, it is useful in the manufacture of cooking utensils.\n"]], ["block_11", ["children under six or pregnant women. The FDA conclusions are in line with the opinions of the\nEnvironmental Protection Agency (EPA) and Centers for Disease Control (CDC). The only health\nconsideration noted is that some people are allergic to the amalgam or one of its components.\n"]], ["block_12", ["LINK TO LEARNING\n"]], ["block_13", [" 18.1 \u2022 Periodicity \n 865 \n"]]], "page_879": [["block_0", [" 866 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["Aluminum is a very good reducing agent and may replace other reducing agents in the isolation of certain\nmetals from their oxides. Although more expensive than reduction by carbon, aluminum is important in the\nisolation of Mo, W, and Cr from their oxides.\n"]], ["block_2", [" Group 14 \n"]], ["block_3", ["The metallic members of group 14 are tin, lead, and flerovium. Carbon is a typical nonmetal. The remaining\nelements of the group, silicon and germanium, are examples of semimetals or metalloids. Tin and lead form\nthe stable divalent cations, Snand Pb, with oxidation states two below the group oxidation state of 4+. The\nstability of this oxidation state is a consequence of the inert pair effect. Tin and lead also form covalent\ncompounds with a formal 4+-oxidation state. For example, SnCl4 and PbCl4 are low-boiling covalent liquids.\n"]], ["block_4", ["Tin reacts readily with nonmetals and acids to form tin(II) compounds (indicating that it is more easily\noxidized than hydrogen) and with nonmetals to form either tin(II) or tin(IV) compounds (shown in Figure 18.9),\ndepending on the stoichiometry and reaction conditions. Lead is less reactive. It is only slightly easier to\noxidize than hydrogen, and oxidation normally requires a hot concentrated acid.\n"]], ["block_5", ["Many of these elements exist as allotropes. Allotropes are two or more forms of the same element in the same\nphysical state with different chemical and physical properties. There are two common allotropes of tin. These\nallotropes are grey (brittle) tin and white tin. As with other allotropes, the difference between these forms of tin\nis in the arrangement of the atoms. White tin is stable above 13.2 \u00b0C and is malleable like other metals. At low\ntemperatures, gray tin is the more stable form. Gray tin is brittle and tends to break down to a powder.\nConsequently, articles made of tin will disintegrate in cold weather, particularly if the cold spell is lengthy. The\nchange progresses slowly from the spot of origin, and the gray tin that is first formed catalyzes further change.\nIn a way, this effect is similar to the spread of an infection in a plant or animal body, leading people to call this\nprocess tin disease or tin pest.\n"]], ["block_6", ["The principal use of tin is in the coating of steel to form tin plate-sheet iron, which constitutes the tin in tin\ncans. Important tin alloys are bronze (Cu and Sn) and solder (Sn and Pb). Lead is important in the lead storage\nbatteries in automobiles.\n"]], ["block_7", [" Group 15 \n"]], ["block_8", [" Bismuth , the heaviest member of group 15, is a less reactive metal than the other representative metals. It\nreadily gives up three of its five valence electrons to active nonmetals to form the tri-positive ion, Bi. It forms\ncompounds with the group oxidation state of 5+ only when treated with strong oxidizing agents. The stability of\nthe 3+-oxidation state is another example of the inert pair effect.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", [" FIGURE 18.9 \n(a) Tin(II) chloride is an ionic solid; (b) tin(IV) chloride is a covalent liquid.\n"]], ["block_11", [{"image_0": "879_0.png", "coords": [130, 190, 481, 346]}]]], "page_880": [["block_0", [" 18.2 Occurrence and Preparation of the Representative Metals \n"]], ["block_1", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_2", ["Because of their reactivity, we do not find most representative metals as free elements in nature. However,\ncompounds that contain ions of most representative metals are abundant. In this section, we will consider the\ntwo common techniques used to isolate the metals from these compounds\u2014electrolysis and chemical\nreduction.\n"]], ["block_3", ["These metals primarily occur in minerals, with lithium found in silicate or phosphate minerals, and sodium\nand potassium found in salt deposits from evaporation of ancient seas and in silicates. The alkaline earth\nmetals occur as silicates and, with the exception of beryllium, as carbonates and sulfates. Beryllium occurs as\nthe mineral beryl, Be3Al2Si6O18, which, with certain impurities, may be either the gemstone emerald or\naquamarine. Magnesium is in seawater and, along with the heavier alkaline earth metals, occurs as silicates,\ncarbonates, and sulfates. Aluminum occurs abundantly in many types of clay and in bauxite, an impure\naluminum oxide hydroxide. The principle tin ore is the oxide cassiterite, SnO2, and the principle lead and\nthallium ores are the sulfides or the products of weathering of the sulfides. The remaining representative\nmetals occur as impurities in zinc or aluminum ores.\n"]], ["block_4", [" Electrolysis \n"]], ["block_5", ["Ions of metals in of groups 1 and 2, along with aluminum, are very difficult to reduce; therefore, it is necessary\nto prepare these elements by electrolysis, an important process discussed in the chapter on electrochemistry.\nBriefly, electrolysis involves using electrical energy to drive unfavorable chemical reactions to completion; it is\nuseful in the isolation of reactive metals in their pure forms. Sodium, aluminum, and magnesium are typical\nexamples.\n"]], ["block_6", [" The Preparation of Sodium \nThe most important method for the production of sodium is the electrolysis of molten sodium chloride; the\nset-up is a Downs cell , shown in Figure 18.10. The reaction involved in this process is:\n"]], ["block_7", ["The electrolysis cell contains molten sodium chloride (melting point 801 \u00b0C), to which calcium chloride has\nbeen added to lower the melting point to 600 \u00b0C (a colligative effect). The passage of a direct current through\nthe cell causes the sodium ions to migrate to the negatively charged cathode and pick up electrons, reducing\nthe ions to sodium metal. Chloride ions migrate to the positively charged anode, lose electrons, and undergo\noxidation to chlorine gas. The overall cell reaction comes from adding the following reactions:\n"]], ["block_8", ["Separation of the molten sodium and chlorine prevents recombination. The liquid sodium, which is less dense\nthan molten sodium chloride, floats to the surface and flows into a collector. The gaseous chlorine goes to\nstorage tanks. Chlorine is also a valuable product.\n"]], ["block_9", ["\u2022\nIdentify natural sources of representative metals\n"]], ["block_10", ["\u2022\nDescribe electrolytic and chemical reduction processes used to prepare these elements from natural sources\n"]], ["block_11", [" 18.2 \u2022 Occurrence and Preparation of the Representative Metals \n 867 \n"]]], "page_881": [["block_0", [" 868 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", [" FIGURE 18.10 \nPure sodium metal is isolated by electrolysis of molten sodium chloride using a Downs cell. It is not\n"]], ["block_2", ["possible to isolate sodium by electrolysis of aqueous solutions of sodium salts because hydrogen ions are more\neasily reduced than are sodium ions; as a result, hydrogen gas forms at the cathode instead of the desired sodium\nmetal. The high temperature required to melt NaCl means that liquid sodium metal forms.\n"]], ["block_3", [" The Preparation of Aluminum \nThe preparation of aluminum utilizes a process invented in 1886 by Charles M. Hall, who began to work on the\nproblem while a student at Oberlin College in Ohio. Paul L. T. H\u00e9roult discovered the process independently a\nmonth or two later in France. In honor to the two inventors, this electrolysis cell is known as the Hall\u2013H\u00e9roult \n cell . The Hall\u2013H\u00e9roult cell is an electrolysis cell for the production of aluminum. Figure 18.11 illustrates the\nHall\u2013H\u00e9roult cell.\n"]], ["block_4", ["The production of aluminum begins with the purification of bauxite, the most common source of aluminum.\nThe reaction of bauxite, AlO(OH), with hot sodium hydroxide forms soluble sodium aluminate, while clay and\nother impurities remain undissolved:\n"]], ["block_5", ["After the removal of the impurities by filtration, the addition of acid to the aluminate leads to the\nreprecipitation of aluminum hydroxide:\n"]], ["block_6", ["The next step is to remove the precipitated aluminum hydroxide by filtration. Heating the hydroxide produces\naluminum oxide, Al2O3, which dissolves in a molten mixture of cryolite, Na3AlF6, and calcium fluoride, CaF2.\nElectrolysis of this solution takes place in a cell like that shown in Figure 18.11. Reduction of aluminum ions to\nthe metal occurs at the cathode, while oxygen, carbon monoxide, and carbon dioxide form at the anode.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [{"image_0": "881_0.png", "coords": [130, 57, 481, 357]}]]], "page_882": [["block_0", [{"image_0": "882_0.png", "coords": [72, 57, 540, 349]}]], ["block_1", [" FIGURE 18.11 \nAn electrolytic cell is used for the production of aluminum. The electrolysis of a solution of cryolite\n"]], ["block_2", ["and calcium fluoride results in aluminum metal at the cathode, and oxygen, carbon monoxide, and carbon dioxide at\nthe anode.\n"]], ["block_3", [" The Preparation of Magnesium \nMagnesium is the other metal that is isolated in large quantities by electrolysis. Seawater, which contains\napproximately 0.5% magnesium chloride, serves as the major source of magnesium. Addition of calcium\nhydroxide to seawater precipitates magnesium hydroxide. The addition of hydrochloric acid to magnesium\nhydroxide, followed by evaporation of the resultant aqueous solution, leaves pure magnesium chloride. The\nelectrolysis of molten magnesium chloride forms liquid magnesium and chlorine gas:\n"]], ["block_4", ["Some production facilities have moved away from electrolysis completely. In the next section, we will see how\nthe Pidgeon process leads to the chemical reduction of magnesium.\n"]], ["block_5", [" Chemical Reduction \n"]], ["block_6", ["It is possible to isolate many of the representative metals by chemical reduction using other elements as\nreducing agents. In general, chemical reduction is much less expensive than electrolysis, and for this reason,\nchemical reduction is the method of choice for the isolation of these elements. For example, it is possible to\nproduce potassium, rubidium, and cesium by chemical reduction, as it is possible to reduce the molten\nchlorides of these metals with sodium metal. This may be surprising given that these metals are more reactive\nthan sodium; however, the metals formed are more volatile than sodium and can be distilled for collection. The\nremoval of the metal vapor leads to a shift in the equilibrium to produce more metal (see how reactions can be\ndriven in the discussions of Le Ch\u00e2telier\u2019s principle in the chapter on fundamental equilibrium concepts).\n"]], ["block_7", ["The production of magnesium, zinc, and tin provide additional examples of chemical reduction.\n"]], ["block_8", [" 18.2 \u2022 Occurrence and Preparation of the Representative Metals \n 869 \n"]]], "page_883": [["block_0", [" 870 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", [" The Preparation of Magnesium \nThe Pidgeon process involves the reaction of magnesium oxide with elemental silicon at high temperatures to\nform pure magnesium:\n"]], ["block_2", ["Although this reaction is unfavorable in terms of thermodynamics, the removal of the magnesium vapor\nproduced takes advantage of Le Ch\u00e2telier\u2019s principle to continue the forward progress of the reaction. Over\n75% of the world\u2019s production of magnesium, primarily in China, comes from this process.\n"]], ["block_3", [" The Preparation of Zinc \nZinc ores usually contain zinc sulfide, zinc oxide, or zinc carbonate. After separation of these compounds from\nthe ores, heating in air converts the ore to zinc oxide by one of the following reactions:\n"]], ["block_4", ["Carbon, in the form of coal, reduces the zinc oxide to form zinc vapor:\n"]], ["block_5", ["The zinc can be distilled (boiling point 907 \u00b0C) and condensed. This zinc contains impurities of cadmium (767\n\u00b0C), iron (2862 \u00b0C), lead (1750 \u00b0C), and arsenic (613 \u00b0C). Careful redistillation produces pure zinc. Arsenic and\ncadmium are distilled from the zinc because they have lower boiling points. At higher temperatures, the zinc is\ndistilled from the other impurities, mainly lead and iron.\n"]], ["block_6", [" The Preparation of Tin \nThe ready reduction of tin(IV) oxide by the hot coals of a campfire accounts for the knowledge of tin in the\nancient world. In the modern process, the roasting of tin ores containing SnO2 removes contaminants such as\narsenic and sulfur as volatile oxides. Treatment of the remaining material with hydrochloric acid removes the\noxides of other metals. Heating the purified ore with carbon at temperature above 1000 \u00b0C produces tin:\n"]], ["block_7", ["The molten tin collects at the bottom of the furnace and is drawn off and cast into blocks.\n"]], ["block_8", [" 18.3 Structure and General Properties of the Metalloids \n"]], ["block_9", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_10", ["A series of six elements called the metalloids separate the metals from the nonmetals in the periodic table. The\nmetalloids are boron, silicon, germanium, arsenic, antimony, and tellurium. These elements look metallic;\nhowever, they do not conduct electricity as well as metals so they are semiconductors. They are\nsemiconductors because their electrons are more tightly bound to their nuclei than are those of metallic\nconductors. Their chemical behavior falls between that of metals and nonmetals. For example, the pure\nmetalloids form covalent crystals like the nonmetals, but like the metals, they generally do not form\nmonatomic anions. This intermediate behavior is in part due to their intermediate electronegativity values. In\nthis section, we will briefly discuss the chemical behavior of metalloids and deal with two of these\nelements\u2014boron and silicon\u2014in more detail.\n"]], ["block_11", ["The metalloid boron exhibits many similarities to its neighbor carbon and its diagonal neighbor silicon. All\nthree elements form covalent compounds. However, boron has one distinct difference in that its 2s2pouter\nelectron structure gives it one less valence electron than it has valence orbitals. Although boron exhibits an\noxidation state of 3+ in most of its stable compounds, this electron deficiency provides boron with the ability to\nform other, sometimes fractional, oxidation states, which occur, for example, in the boron hydrides.\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["\u2022\nDescribe the general preparation, properties, and uses of the metalloids\n"]], ["block_14", ["\u2022\nDescribe the preparation, properties, and compounds of boron and silicon\n"]]], "page_884": [["block_0", ["Silicon has the valence shell electron configuration 3s3p, and it commonly forms tetrahedral structures in\nwhich it is sphybridized with a formal oxidation state of 4+. The major differences between the chemistry of\ncarbon and silicon result from the relative strength of the carbon-carbon bond, carbon\u2019s ability to form stable\nbonds to itself, and the presence of the empty 3d valence-shell orbitals in silicon. Silicon\u2019s empty d orbitals and\nboron\u2019s empty p orbital enable tetrahedral silicon compounds and trigonal planar boron compounds to act as\nLewis acids. Carbon, on the other hand, has no available valence shell orbitals; tetrahedral carbon compounds\ncannot act as Lewis acids. Germanium is very similar to silicon in its chemical behavior.\n"]], ["block_1", ["Arsenic and antimony generally form compounds in which an oxidation state of 3+ or 5+ is exhibited; however,\narsenic can form arsenides with an oxidation state of 3\u2212. These elements tarnish only slightly in dry air but\nreadily oxidize when warmed.\n"]], ["block_2", ["Tellurium combines directly with most elements. The most stable tellurium compounds are the\ntellurides\u2014salts of Teformed with active metals and lanthanides\u2014and compounds with oxygen, fluorine, and\nchlorine, in which tellurium normally exhibits an oxidation state 2+ or 4+. Although tellurium(VI) compounds\nare known (for example, TeF6), there is a marked resistance to oxidation to this maximum group oxidation\nstate.\n"]], ["block_3", [" Structures of the Metalloids \n"]], ["block_4", ["Covalent bonding is the key to the crystal structures of the metalloids. In this regard, these elements resemble\nnonmetals in their behavior.\n"]], ["block_5", ["Elemental silicon, germanium, arsenic, antimony, and tellurium are lustrous, metallic-looking solids. Silicon\nand germanium crystallize with a diamond structure. Each atom within the crystal has covalent bonds to four\nneighboring atoms at the corners of a regular tetrahedron. Single crystals of silicon and germanium are giant,\nthree-dimensional molecules. There are several allotropes of arsenic with the most stable being layer like and\ncontaining puckered sheets of arsenic atoms. Each arsenic atom forms covalent bonds to three other atoms\nwithin the sheet. The crystal structure of antimony is similar to that of arsenic, both shown in Figure 18.12.\nThe structures of arsenic and antimony are similar to the structure of graphite, covered later in this chapter.\nTellurium forms crystals that contain infinite spiral chains of tellurium atoms. Each atom in the chain bonds to\ntwo other atoms.\n"]], ["block_6", ["Explore a cubic diamond (http://openstax.org/l/16crystal) crystal structure.\n"]], ["block_7", [{"image_0": "884_0.png", "coords": [72, 489, 540, 629]}]], ["block_8", [" FIGURE 18.12 \n(a) Arsenic and (b) antimony have a layered structure similar to that of (c) graphite, except that the\n"]], ["block_9", ["layers are puckered rather than planar. (d) Elemental tellurium forms spiral chains.\n"]], ["block_10", ["Pure crystalline boron is transparent. The crystals consist of icosahedra, as shown in Figure 18.13, with a\nboron atom at each corner. In the most common form of boron, the icosahedra pack together in a manner\nsimilar to the cubic closest packing of spheres. All boron-boron bonds within each icosahedron are identical\nand are approximately 176 pm in length. In the different forms of boron, there are different arrangements and\nconnections between the icosahedra.\n"]], ["block_11", ["LINK TO LEARNING\n"]], ["block_12", [" 18.3 \u2022 Structure and General Properties of the Metalloids \n 871 \n"]]], "page_885": [["block_0", [" 872 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", [" FIGURE 18.13 \nAn icosahedron is a symmetrical, solid shape with 20 faces, each of which is an equilateral triangle.\n"]], ["block_2", ["The faces meet at 12 corners.\n"]], ["block_3", ["The name silicon is derived from the Latin word for flint, silex. The metalloid silicon readily forms compounds\ncontaining Si-O-Si bonds, which are of prime importance in the mineral world. This bonding capability is in\ncontrast to the nonmetal carbon, whose ability to form carbon-carbon bonds gives it prime importance in the\nplant and animal worlds.\n"]], ["block_4", [" Occurrence, Preparation, and Compounds of Boron and Silicon \n"]], ["block_5", ["Boron constitutes less than 0.001% by weight of the earth\u2019s crust. In nature, it only occurs in compounds with\noxygen. Boron is widely distributed in volcanic regions as boric acid, B(OH)3, and in dry lake regions, including\nthe desert areas of California, as borates and salts of boron oxyacids, such as borax, Na2B4O7\u22c510H2O.\n"]], ["block_6", ["Elemental boron is chemically inert at room temperature, reacting with only fluorine and oxygen to form\nboron trifluoride, BF3, and boric oxide, B2O3, respectively. At higher temperatures, boron reacts with all\nnonmetals, except tellurium and the noble gases, and with nearly all metals; it oxidizes to B2O3 when heated\nwith concentrated nitric or sulfuric acid. Boron does not react with nonoxidizing acids. Many boron\ncompounds react readily with water to give boric acid, B(OH)3 (sometimes written as H3BO3).\n"]], ["block_7", ["Reduction of boric oxide with magnesium powder forms boron (95\u201398.5% pure) as a brown, amorphous\npowder:\n"]], ["block_8", ["An amorphous substance is a material that appears to be a solid, but does not have a long-range order like a\ntrue solid. Treatment with hydrochloric acid removes the magnesium oxide. Further purification of the boron\nbegins with conversion of the impure boron into boron trichloride. The next step is to heat a mixture of boron\ntrichloride and hydrogen:\n"]], ["block_9", ["Silicon makes up nearly one-fourth of the mass of the earth\u2019s crust\u2014second in abundance only to oxygen. The\ncrust is composed almost entirely of minerals in which the silicon atoms are at the center of the silicon-oxygen\ntetrahedron, which connect in a variety of ways to produce, among other things, chains, layers, and three-\ndimensional frameworks. These minerals constitute the bulk of most common rocks, soil, and clays. In\naddition, materials such as bricks, ceramics, and glasses contain silicon compounds.\n"]], ["block_10", ["It is possible to produce silicon by the high-temperature reduction of silicon dioxide with strong reducing\nagents, such as carbon and magnesium:\n"]], ["block_11", ["Extremely pure silicon is necessary for the manufacture of semiconductor electronic devices. This process\nbegins with the conversion of impure silicon into silicon tetrahalides, or silane (SiH4), followed by\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", [{"image_0": "885_0.png", "coords": [247, 57, 364, 178]}]]], "page_886": [["block_0", ["decomposition at high temperatures. Zone refining, illustrated in Figure 18.14, completes the purification. In\nthis method, a rod of silicon is heated at one end by a heat source that produces a thin cross-section of molten\nsilicon. Slowly lowering the rod through the heat source moves the molten zone from one end of the rod to\nother. As this thin, molten region moves, impurities in the silicon dissolve in the liquid silicon and move with\nthe molten region. Ultimately, the impurities move to one end of the rod, which is then cut off.\n"]], ["block_1", ["This highly purified silicon, containing no more than one part impurity per million parts of silicon, is the most\nimportant element in the computer industry. Pure silicon is necessary in semiconductor electronic devices\nsuch as transistors, computer chips, and solar cells.\n"]], ["block_2", ["Like some metals, passivation of silicon occurs due the formation of a very thin film of oxide (primarily silicon\ndioxide, SiO2). Silicon dioxide is soluble in hot aqueous base; thus, strong bases destroy the passivation.\nRemoval of the passivation layer allows the base to dissolve the silicon, forming hydrogen gas and silicate\nanions. For example:\n"]], ["block_3", ["Silicon reacts with halogens at high temperatures, forming volatile tetrahalides, such as SiF4.\n"]], ["block_4", ["Unlike carbon, silicon does not readily form double or triple bonds. Silicon compounds of the general formula\nSiX4, where X is a highly electronegative group, can act as Lewis acids to form six-coordinate silicon. For\nexample, silicon tetrafluoride, SiF4, reacts with sodium fluoride to yield Na2[SiF6], which contains the\n"]], ["block_5", ["octahedral\nion in which silicon is spdhybridized:\n"]], ["block_6", [" FIGURE 18.14 \nA zone-refining apparatus used to purify silicon.\n"]], ["block_7", [{"image_0": "886_0.png", "coords": [189, 126, 422, 508]}]], ["block_8", [" 18.3 \u2022 Structure and General Properties of the Metalloids \n 873 \n"]]], "page_887": [["block_0", [" 874 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["Antimony reacts readily with stoichiometric amounts of fluorine, chlorine, bromine, or iodine, yielding\ntrihalides or, with excess fluorine or chlorine, forming the pentahalides SbF5 and SbCl5. Depending on the\nstoichiometry, it forms antimony(III) sulfide, Sb2S3, or antimony(V) sulfide when heated with sulfur. As\nexpected, the metallic nature of the element is greater than that of arsenic, which lies immediately above it in\ngroup 15.\n"]], ["block_2", [" Boron and Silicon Halides \nBoron trihalides\u2014BF3, BCl3, BBr3, and BI3\u2014can be prepared by the direct reaction of the elements. These\nnonpolar molecules contain boron with sphybridization and a trigonal planar molecular geometry. The\nfluoride and chloride compounds are colorless gasses, the bromide is a liquid, and the iodide is a white\ncrystalline solid.\n"]], ["block_3", ["Except for boron trifluoride, the boron trihalides readily hydrolyze in water to form boric acid and the\ncorresponding hydrohalic acid. Boron trichloride reacts according to the equation:\n"]], ["block_4", ["Boron trifluoride reacts with hydrofluoric acid, to yield a solution of fluoroboric acid, HBF4:\n"]], ["block_5", ["In this reaction, the BF3 molecule acts as the Lewis acid (electron pair acceptor) and accepts a pair of electrons\nfrom a fluoride ion:\n"]], ["block_6", [{"image_0": "887_0.png", "coords": [72, 331, 231, 377]}]], ["block_7", ["All the tetrahalides of silicon, SiX4, have been prepared. Silicon tetrachloride can be prepared by direct\nchlorination at elevated temperatures or by heating silicon dioxide with chlorine and carbon:\n"]], ["block_8", ["Silicon tetrachloride is a covalent tetrahedral molecule, which is a nonpolar, low-boiling (57 \u00b0C), colorless\nliquid.\n"]], ["block_9", ["It is possible to prepare silicon tetrafluoride by the reaction of silicon dioxide with hydrofluoric acid:\n"]], ["block_10", ["Hydrofluoric acid is the only common acid that will react with silicon dioxide or silicates. This reaction occurs\nbecause the silicon-fluorine bond is the only bond that silicon forms that is stronger than the silicon-oxygen\nbond. For this reason, it is possible to store all common acids, other than hydrofluoric acid, in glass containers.\n"]], ["block_11", ["Except for silicon tetrafluoride, silicon halides are extremely sensitive to water. Upon exposure to water, SiCl4\nreacts rapidly with hydroxide groups, replacing all four chlorine atoms to produce unstable orthosilicic acid,\nSi(OH)4 or H4SiO4, which slowly decomposes into SiO2.\n"]], ["block_12", [" Boron and Silicon Oxides and Derivatives \nBoron burns at 700 \u00b0C in oxygen, forming boric oxide, B2O3. Boric oxide is necessary for the production of\nheat-resistant borosilicate glass, like that shown in Figure 18.15 and certain optical glasses. Boric oxide\ndissolves in hot water to form boric acid, B(OH)3:\n"]], ["block_13", [" Access for free at openstax.org \n"]]], "page_888": [["block_0", [" FIGURE 18.15 \nLaboratory glassware, such as Pyrex and Kimax, is made of borosilicate glass because it does not\n"]], ["block_1", ["break when heated. The inclusion of borates in the glass helps to mediate the effects of thermal expansion and\ncontraction. This reduces the likelihood of thermal shock, which causes silicate glass to crack upon rapid heating or\ncooling. (credit: \u201cTweenk\u201d/Wikimedia Commons)\n"]], ["block_2", ["The boron atom in B(OH)3 is sphybridized and is located at the center of an equilateral triangle with oxygen\natoms at the corners. In solid B(OH)3, hydrogen bonding holds these triangular units together. Boric acid,\nshown in Figure 18.16, is a very weak acid that does not act as a proton donor but rather as a Lewis acid,\naccepting an unshared pair of electrons from the Lewis base OH:\n"]], ["block_3", [" FIGURE 18.16 \nBoric acid has a planar structure with three \u2013OH groups spread out equally at 120\u00b0 angles from\n"]], ["block_4", ["each other.\n"]], ["block_5", ["Heating boric acid to 100 \u00b0C causes molecules of water to split out between pairs of adjacent \u2013OH groups to\nform metaboric acid, HBO2. At about 150 \u00b0C, additional B-O-B linkages form, connecting the BO3 groups\ntogether with shared oxygen atoms to form tetraboric acid, H2B4O7. Complete water loss, at still higher\ntemperatures, results in boric oxide.\n"]], ["block_6", [" Borates are salts of the oxyacids of boron. Borates result from the reactions of a base with an oxyacid or from\nthe fusion of boric acid or boric oxide with a metal oxide or hydroxide. Borate anions range from the simple\ntrigonal planar\nion to complex species containing chains and rings of three- and four-coordinated\n"]], ["block_7", ["boron atoms. The structures of the anions found in CaB2O4, K[B5O6(OH)4]\u22c52H2O (commonly written\nKB5O8\u22c54H2O) and Na2[B4O5(OH)4]\u22c58H2O (commonly written Na2B4O7\u22c510H2O) are shown in Figure 18.17.\nCommercially, the most important borate is borax, Na2[B4O5(OH)4]\u22c58H2O, which is an important component of\nsome laundry detergents. Most of the supply of borax comes directly from dry lakes, such as Searles Lake in\nCalifornia, or is prepared from kernite, Na2B4O7\u22c54H2O.\n"]], ["block_8", [{"image_0": "888_0.png", "coords": [189, 57, 423, 240]}]], ["block_9", [{"image_1": "888_1.png", "coords": [247, 376, 364, 446]}]], ["block_10", [" 18.3 \u2022 Structure and General Properties of the Metalloids \n 875 \n"]]], "page_889": [["block_0", [" 876 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["Silicon dioxide, silica, occurs in both crystalline and amorphous forms. The usual crystalline form of silicon\ndioxide is quartz, a hard, brittle, clear, colorless solid. It is useful in many ways\u2014for architectural decorations,\nsemiprecious jewels, and frequency control in radio transmitters. Silica takes many crystalline forms, or\n polymorphs , in nature. Trace amounts of Fein quartz give amethyst its characteristic purple color. The term\nquartz is also used for articles such as tubing and lenses that are manufactured from amorphous silica. Opal is\na naturally occurring form of amorphous silica.\n"]], ["block_2", [{"image_0": "889_0.png", "coords": [72, 57, 540, 203]}]], ["block_3", [" FIGURE 18.17 \nThe borate anions are (a) CaB2O4, (b) KB5O8\u22c54H2O, and (c) Na2B4O7\u22c510H2O. The anion in CaB2O4 is\n"]], ["block_4", ["an \u201cinfinite\u201d chain.\n"]], ["block_5", ["The contrast in structure and physical properties between silicon dioxide and carbon dioxide is interesting, as\nillustrated in Figure 18.18. Solid carbon dioxide (dry ice) contains single CO2 molecules with each of the two\noxygen atoms attached to the carbon atom by double bonds. Very weak intermolecular forces hold the\nmolecules together in the crystal. The volatility of dry ice reflect these weak forces between molecules. In\ncontrast, silicon dioxide is a covalent network solid. In silicon dioxide, each silicon atom links to four oxygen\natoms by single bonds directed toward the corners of a regular tetrahedron, and SiO4 tetrahedra share oxygen\natoms. This arrangement gives a three dimensional, continuous, silicon-oxygen network. A quartz crystal is a\nmacromolecule of silicon dioxide. The difference between these two compounds is the ability of the group 14\nelements to form strong \u03c0 bonds. Second-period elements, such as carbon, form very strong \u03c0 bonds, which is\nwhy carbon dioxide forms small molecules with strong double bonds. Elements below the second period, such\nas silicon, do not form \u03c0 bonds as readily as second-period elements, and when they do form, the \u03c0 bonds are\nweaker than those formed by second-period elements. For this reason, silicon dioxide does not contain \u03c0\nbonds but only \u03c3 bonds.\n"]], ["block_6", [" Access for free at openstax.org \n"]]], "page_890": [["block_0", [" FIGURE 18.18 \nBecause carbon tends to form double and triple bonds and silicon does not, (a) carbon dioxide is a\n"]], ["block_1", ["discrete molecule with two C=O double bonds and (b) silicon dioxide is an infinite network of oxygen atoms bridging\nbetween silicon atoms with each silicon atom possessing four Si-O single bonds. (credit a photo: modification of\nwork by Erica Gerdes; credit b photo: modification of work by Didier Descouens)\n"]], ["block_2", ["At 1600 \u00b0C, quartz melts to yield a viscous liquid. When the liquid cools, it does not crystallize readily but\nusually supercools and forms a glass, also called silica. The SiO4 tetrahedra in glassy silica have a random\narrangement characteristic of supercooled liquids, and the glass has some very useful properties. Silica is\nhighly transparent to both visible and ultraviolet light. For this reason, it is important in the manufacture of\nlamps that give radiation rich in ultraviolet light and in certain optical instruments that operate with\nultraviolet light. The coefficient of expansion of silica glass is very low; therefore, rapid temperature changes\ndo not cause it to fracture. CorningWare and other ceramic cookware contain amorphous silica.\n"]], ["block_3", [" Silicates are salts containing anions composed of silicon and oxygen. In nearly all silicates, sp-hybridized\nsilicon atoms occur at the centers of tetrahedra with oxygen at the corners. There is a variation in the silicon-\nto-oxygen ratio that occurs because silicon-oxygen tetrahedra may exist as discrete, independent units or may\nshare oxygen atoms at corners in a variety of ways. In addition, the presence of a variety of cations gives rise to\nthe large number of silicate minerals.\n"]], ["block_4", ["Many ceramics are composed of silicates. By including small amounts of other compounds, it is possible to\nmodify the physical properties of the silicate materials to produce ceramics with useful characteristics.\n"]], ["block_5", [" 18.4 Structure and General Properties of the Nonmetals \n"]], ["block_6", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_7", ["\u2022\nDescribe structure and properties of nonmetals\n"]], ["block_8", [{"image_0": "890_0.png", "coords": [123, 57, 488, 412]}]], ["block_9", [" 18.4 \u2022 Structure and General Properties of the Nonmetals \n 877 \n"]]], "page_891": [["block_0", [" 878 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["The nonmetals are elements located in the upper right portion of the periodic table. Their properties and\nbehavior are quite different from those of metals on the left side. Under normal conditions, more than half of\nthe nonmetals are gases, one is a liquid, and the rest include some of the softest and hardest of solids. The\nnonmetals exhibit a rich variety of chemical behaviors. They include the most reactive and least reactive of\nelements, and they form many different ionic and covalent compounds. This section presents an overview of\nthe properties and chemical behaviors of the nonmetals, as well as the chemistry of specific elements. Many of\nthese nonmetals are important in biological systems.\n"]], ["block_2", ["In many cases, trends in electronegativity enable us to predict the type of bonding and the physical states in\ncompounds involving the nonmetals. We know that electronegativity decreases as we move down a given\ngroup and increases as we move from left to right across a period. The nonmetals have higher\nelectronegativities than do metals, and compounds formed between metals and nonmetals are generally ionic\nin nature because of the large differences in electronegativity between them. The metals form cations, the\nnonmetals form anions, and the resulting compounds are solids under normal conditions. On the other hand,\ncompounds formed between two or more nonmetals have small differences in electronegativity between the\natoms, and covalent bonding\u2014sharing of electrons\u2014results. These substances tend to be molecular in nature\nand are gases, liquids, or volatile solids at room temperature and pressure.\n"]], ["block_3", ["In normal chemical processes, nonmetals do not form monatomic positive ions (cations) because their\nionization energies are too high. All monatomic nonmetal ions are anions; examples include the chloride ion,\nCl, the nitride ion, N, and the selenide ion, Se.\n"]], ["block_4", ["The common oxidation states that the nonmetals exhibit in their ionic and covalent compounds are shown in\nFigure 18.19. Remember that an element exhibits a positive oxidation state when combined with a more\nelectronegative element and that it exhibits a negative oxidation state when combined with a less\nelectronegative element.\n"]], ["block_5", [{"image_0": "891_0.png", "coords": [72, 372, 540, 460]}]], ["block_6", ["The first member of each nonmetal group exhibits different behaviors, in many respects, from the other group\nmembers. The reasons for this include smaller size, greater ionization energy, and (most important) the fact\nthat the first member of each group has only four valence orbitals (one 2s and three 2p) available for bonding,\nwhereas other group members have empty d orbitals in their valence shells, making possible five, six, or even\nmore bonds around the central atom. For example, nitrogen forms only NF3, whereas phosphorus forms both\nPF3 and PF5.\n"]], ["block_7", ["Another difference between the first group member and subsequent members is the greater ability of the first\nmember to form \u03c0 bonds. This is primarily a function of the smaller size of the first member of each group,\nwhich allows better overlap of atomic orbitals. Nonmetals, other than the first member of each group, rarely\nform \u03c0 bonds to nonmetals that are the first member of a group. For example, sulfur-oxygen \u03c0 bonds are well\nknown, whereas sulfur does not normally form stable \u03c0 bonds to itself.\n"]], ["block_8", ["The variety of oxidation states displayed by most of the nonmetals means that many of their chemical\nreactions involve changes in oxidation state through oxidation-reduction reactions. There are five general\naspects of the oxidation-reduction chemistry:\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["1.\nNonmetals oxidize most metals. The oxidation state of the metal becomes positive as it undergoes\noxidation and that of the nonmetal becomes negative as it undergoes reduction. For example:\n"]], ["block_11", [" FIGURE 18.19 \nNonmetals exhibit these common oxidation states in ionic and covalent compounds.\n"]]], "page_892": [["block_0", ["With the exception of most of the noble gases, all nonmetals form compounds with oxygen, yielding covalent\noxides. Most of these oxides are acidic, that is, they react with water to form oxyacids. Recall from the acid-base\nchapter that an oxyacid is an acid consisting of hydrogen, oxygen, and some other element. Notable exceptions\nare carbon monoxide, CO, nitrous oxide, N2O, and nitric oxide, NO. There are three characteristics of these\nacidic oxides:\n"]], ["block_1", ["The binary hydrogen compounds of the nonmetals also exhibit an acidic behavior in water, although only HCl,\nHBr, and HI are strong acids. The acid strength of the nonmetal hydrogen compounds increases from left to\nright across a period and down a group. For example, ammonia, NH3, is a weaker acid than is water, H2O,\nwhich is weaker than is hydrogen fluoride, HF. Water, H2O, is also a weaker acid than is hydrogen sulfide, H2S,\nwhich is weaker than is hydrogen selenide, H2Se. Weaker acidic character implies greater basic character.\n"]], ["block_2", [" Structures of the Nonmetals \n"]], ["block_3", ["The structures of the nonmetals differ dramatically from those of metals. Metals crystallize in closely packed\narrays that do not contain molecules or covalent bonds. Nonmetal structures contain covalent bonds, and\nmany nonmetals consist of individual molecules. The electrons in nonmetals are localized in covalent bonds,\n"]], ["block_4", ["2.\nWith the exception of nitrogen and carbon, which are poor oxidizing agents, a more electronegative\nnonmetal oxidizes a less electronegative nonmetal or the anion of the nonmetal:\n"]], ["block_5", ["3.\nFluorine and oxygen are the strongest oxidizing agents within their respective groups; each oxidizes all\nthe elements that lie below it in the group. Within any period, the strongest oxidizing agent is in group 17.\nA nonmetal often oxidizes an element that lies to its left in the same period. For example:\n"]], ["block_6", ["4.\nThe stronger a nonmetal is as an oxidizing agent, the more difficult it is to oxidize the anion formed by the\nnonmetal. This means that the most stable negative ions are formed by elements at the top of the group or\nin group 17 of the period.\n"]], ["block_7", ["5.\nFluorine and oxygen are the strongest oxidizing elements known. Fluorine does not form compounds in\nwhich it exhibits positive oxidation states; oxygen exhibits a positive oxidation state only when combined\nwith fluorine. For example:\n"]], ["block_8", ["1.\nOxides such as SO2 and N2O5, in which the nonmetal exhibits one of its common oxidation states, are acid \n anhydrides and react with water to form acids with no change in oxidation state. The product is an\noxyacid. For example:\n"]], ["block_9", ["2.\nThose oxides such as NO2 and ClO2, in which the nonmetal does not exhibit one of its common oxidation\nstates, also react with water. In these reactions, the nonmetal is both oxidized and reduced. For example:\n"]], ["block_10", ["3.\nThe acid strength increases as the electronegativity of the central atom increases. To learn more, see the\ndiscussion in the chapter on acid-base chemistry.\n"]], ["block_11", ["Reactions in which the same element is both oxidized and reduced are called disproportionation \n reactions .\n"]], ["block_12", [" 18.4 \u2022 Structure and General Properties of the Nonmetals \n 879 \n"]]], "page_893": [["block_0", [" 880 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["whereas in a metal, there is delocalization of the electrons throughout the solid.\n"]], ["block_2", ["The noble gases are all monatomic, whereas the other nonmetal gases\u2014hydrogen, nitrogen, oxygen, fluorine,\nand chlorine\u2014normally exist as the diatomic molecules H2, N2, O2, F2, and Cl2. The other halogens are also\ndiatomic; Br2 is a liquid and I2 exists as a solid under normal conditions. The changes in state as one moves\ndown the halogen family offer excellent examples of the increasing strength of intermolecular London forces\nwith increasing molecular mass and increasing polarizability.\n"]], ["block_3", ["Oxygen has two allotropes: O2, dioxygen, and O3, ozone. Phosphorus has three common allotropes, commonly\nreferred to by their colors: white, red, and black. Sulfur has several allotropes. There are also many carbon\nallotropes. Most people know of diamond, graphite, and charcoal, but fewer people know of the recent\ndiscovery of fullerenes, carbon nanotubes, and graphene.\n"]], ["block_4", ["Descriptions of the physical properties of three nonmetals that are characteristic of molecular solids follow.\n"]], ["block_5", [" Carbon \n"]], ["block_6", ["Carbon occurs in the uncombined (elemental) state in many forms, such as diamond, graphite, charcoal, coke,\ncarbon black, graphene, and fullerene.\n"]], ["block_7", ["Diamond, shown in Figure 18.20, is a very hard crystalline material that is colorless and transparent when\npure. Each atom forms four single bonds to four other atoms at the corners of a tetrahedron (sp\n"]], ["block_8", ["hybridization); this makes the diamond a giant molecule. Carbon-carbon single bonds are very strong, and,\nbecause they extend throughout the crystal to form a three-dimensional network, the crystals are very hard\nand have high melting points (~4400 \u00b0C).\n"]], ["block_9", [{"image_0": "893_0.png", "coords": [72, 342, 540, 465]}]], ["block_10", [" FIGURE 18.20 \n(a) Diamond and (b) graphite are two forms of carbon. (c) In the crystal structure of diamond, the\n"]], ["block_11", ["covalent bonds form three-dimensional tetrahedrons. (d) In the crystal structure of graphite, each planar layer is\ncomposed of six-membered rings. (credit a: modification of work by \u201cFancy Diamonds\u201d/Flickr; credit b: modification\nof work from http://images-of-elements.com/carbon.php)\n"]], ["block_12", ["Graphite, also shown in Figure 18.20, is a soft, slippery, grayish-black solid that conducts electricity. These\nproperties relate to its structure, which consists of layers of carbon atoms, with each atom surrounded by three\nother carbon atoms in a trigonal planar arrangement. Each carbon atom in graphite forms three \u03c3 bonds, one\nto each of its nearest neighbors, by means of sp-hybrid orbitals. The unhybridized p orbital on each carbon\natom will overlap unhybridized orbitals on adjacent carbon atoms in the same layer to form \u03c0 bonds. Many\nresonance forms are necessary to describe the electronic structure of a graphite layer; Figure 18.21 illustrates\ntwo of these forms.\n"]], ["block_13", [" Access for free at openstax.org \n"]]], "page_894": [["block_0", [{"image_0": "894_0.png", "coords": [72, 57, 540, 213]}]], ["block_1", [" FIGURE 18.21 \n(a) Carbon atoms in graphite have unhybridized p orbitals. Each p orbital is perpendicular to the\n"]], ["block_2", ["plane of carbon atoms. (b) These are two of the many resonance forms of graphite necessary to describe its\nelectronic structure as a resonance hybrid.\n"]], ["block_3", ["Atoms within a graphite layer are bonded together tightly by the \u03c3 and \u03c0 bonds; however, the forces between\nlayers are weak. London dispersion forces hold the layers together. To learn more, see the discussion of these\nweak forces in the chapter on liquids and solids. The weak forces between layers give graphite the soft, flaky\ncharacter that makes it useful as the so-called \u201clead\u201d in pencils and the slippery character that makes it useful\nas a lubricant. The loosely held electrons in the resonating \u03c0 bonds can move throughout the solid and are\nresponsible for the electrical conductivity of graphite.\n"]], ["block_4", ["Other forms of elemental carbon include carbon black, charcoal, and coke. Carbon black is an amorphous form\nof carbon prepared by the incomplete combustion of natural gas, CH4. It is possible to produce charcoal and\ncoke by heating wood and coal, respectively, at high temperatures in the absence of air.\n"]], ["block_5", ["Recently, new forms of elemental carbon molecules have been identified in the soot generated by a smoky\nflame and in the vapor produced when graphite is heated to very high temperatures in a vacuum or in helium.\nOne of these new forms, first isolated by Professor Richard Smalley and coworkers at Rice University, consists\nof icosahedral (soccer-ball-shaped) molecules that contain 60 carbon atoms, C60. This is buckminsterfullerene\n(often called bucky balls) after the architect Buckminster Fuller, who designed domed structures, which have a\nsimilar appearance (Figure 18.22).\n"]], ["block_6", [" FIGURE 18.22 \nThe molecular structure of C60, buckminsterfullerene, is icosahedral.\n"]], ["block_7", [{"image_1": "894_1.png", "coords": [189, 468, 423, 699]}]], ["block_8", [" 18.4 \u2022 Structure and General Properties of the Nonmetals \n 881 \n"]]], "page_895": [["block_0", [" 882 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", ["Chemistry in Everyday Life\n"]], ["block_3", [" Nanotubes and Graphene \nGraphene and carbon nanotubes are two recently discovered allotropes of carbon. Both of the forms bear\nsome relationship to graphite. Graphene is a single layer of graphite (one atom thick), as illustrated in\nFigure 18.23, whereas carbon nanotubes roll the layer into a small tube, as illustrated in Figure 18.23.\n"]], ["block_4", ["Graphene is a very strong, lightweight, and efficient conductor of heat and electricity discovered in 2003.\nAs in graphite, the carbon atoms form a layer of six-membered rings with sp-hybridized carbon atoms at\nthe corners. Resonance stabilizes the system and leads to its conductivity. Unlike graphite, there is no\nstacking of the layers to give a three-dimensional structure. Andre Geim and Kostya Novoselov at the\nUniversity of Manchester won the 2010 Nobel Prize in Physics for their pioneering work characterizing\ngraphene.\n"]], ["block_5", ["The simplest procedure for preparing graphene is to use a piece of adhesive tape to remove a single layer\nof graphene from the surface of a piece of graphite. This method works because there are only weak\nLondon dispersion forces between the layers in graphite. Alternative methods are to deposit a single layer\nof carbon atoms on the surface of some other material (ruthenium, iridium, or copper) or to synthesize it at\nthe surface of silicon carbide via the sublimation of silicon.\n"]], ["block_6", ["There currently are no commercial applications of graphene. However, its unusual properties, such as high\nelectron mobility and thermal conductivity, should make it suitable for the manufacture of many advanced\nelectronic devices and for thermal management applications.\n"]], ["block_7", ["Carbon nanotubes are carbon allotropes, which have a cylindrical structure. Like graphite and graphene,\nnanotubes consist of rings of sp-hybridized carbon atoms. Unlike graphite and graphene, which occur in\nlayers, the layers wrap into a tube and bond together to produce a stable structure. The walls of the tube\nmay be one atom or multiple atoms thick.\n"]], ["block_8", ["Carbon nanotubes are extremely strong materials that are harder than diamond. Depending upon the\nshape of the nanotube, it may be a conductor or semiconductor. For some applications, the conducting\nform is preferable, whereas other applications utilize the semiconducting form.\n"]], ["block_9", ["The basis for the synthesis of carbon nanotubes is the generation of carbon atoms in a vacuum. It is\npossible to produce carbon atoms by an electrical discharge through graphite, vaporization of graphite\n"]], ["block_10", [{"image_0": "895_0.png", "coords": [90, 142, 522, 373]}]], ["block_11", [" FIGURE 18.23 \n(a) Graphene and (b) carbon nanotubes are both allotropes of carbon.\n"]]], "page_896": [["block_0", [" Phosphorus \n"]], ["block_1", ["The name phosphorus comes from the Greek words meaning light bringing. When phosphorus was first\nisolated, scientists noted that it glowed in the dark and burned when exposed to air. Phosphorus is the only\nmember of its group that does not occur in the uncombined state in nature; it exists in many allotropic forms.\nWe will consider two of those forms: white phosphorus and red phosphorus.\n"]], ["block_2", ["White phosphorus is a white, waxy solid that melts at 44.2 \u00b0C and boils at 280 \u00b0C. It is insoluble in water (in\nwhich it is stored\u2014see Figure 18.24), is very soluble in carbon disulfide, and bursts into flame in air. As a solid,\nas a liquid, as a gas, and in solution, white phosphorus exists as P4 molecules with four phosphorus atoms at\nthe corners of a regular tetrahedron, as illustrated in Figure 18.24. Each phosphorus atom covalently bonds to\nthe other three atoms in the molecule by single covalent bonds. White phosphorus is the most reactive\nallotrope and is very toxic.\n"]], ["block_3", [{"image_0": "896_0.png", "coords": [72, 324, 540, 440]}]], ["block_4", [" FIGURE 18.24 \n(a) Because white phosphorus bursts into flame in air, it is stored in water. (b) The structure of\n"]], ["block_5", ["white phosphorus consists of P4 molecules arranged in a tetrahedron. (c) Red phosphorus is much less reactive than\nis white phosphorus. (d) The structure of red phosphorus consists of networks of P4 tetrahedra joined by P-P single\nbonds. (credit a: modification of work from http://images-of-elements.com/phosphorus.php)\n"]], ["block_6", ["Heating white phosphorus to 270\u2013300 \u00b0C in the absence of air yields red phosphorus. Red phosphorus (shown\nin Figure 18.24) is denser, has a higher melting point (~600 \u00b0C), is much less reactive, is essentially nontoxic,\nand is easier and safer to handle than is white phosphorus. Its structure is highly polymeric and appears to\ncontain three-dimensional networks of P4 tetrahedra joined by P-P single bonds. Red phosphorus is insoluble\nin solvents that dissolve white phosphorus. When red phosphorus is heated, P4 molecules sublime from the\nsolid.\n"]], ["block_7", [" Sulfur \n"]], ["block_8", ["The allotropy of sulfur is far greater and more complex than that of any other element. Sulfur is the brimstone\nreferred to in the Bible and other places, and references to sulfur occur throughout recorded history\u2014right up\nto the relatively recent discovery that it is a component of the atmospheres of Venus and of Io, a moon of\nJupiter. The most common and most stable allotrope of sulfur is yellow, rhombic sulfur, so named because of\nthe shape of its crystals. Rhombic sulfur is the form to which all other allotropes revert at room temperature.\nCrystals of rhombic sulfur melt at 113 \u00b0C. Cooling this liquid gives long needles of monoclinic sulfur. This form\nis stable from 96 \u00b0C to the melting point, 119 \u00b0C. At room temperature, it gradually reverts to the rhombic\nform.\n"]], ["block_9", ["Both rhombic sulfur and monoclinic sulfur contain S8 molecules in which atoms form eight-membered,\npuckered rings that resemble crowns, as illustrated in Figure 18.25. Each sulfur atom is bonded to each of its\n"]], ["block_10", ["with a laser, and the decomposition of a carbon compound.\n"]], ["block_11", ["The strength of carbon nanotubes will eventually lead to some of their most exciting applications, as a\nthread produced from several nanotubes will support enormous weight. However, the current applications\nonly employ bulk nanotubes. The addition of nanotubes to polymers improves the mechanical, thermal,\nand electrical properties of the bulk material. There are currently nanotubes in some bicycle parts, skis,\nbaseball bats, fishing rods, and surfboards.\n"]], ["block_12", [" 18.4 \u2022 Structure and General Properties of the Nonmetals \n 883 \n"]]], "page_897": [["block_0", [" 884 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["two neighbors in the ring by covalent S-S single bonds.\n"]], ["block_2", [{"image_0": "897_0.png", "coords": [72, 76, 540, 505]}]], ["block_3", [" FIGURE 18.25 \nThese four sulfur allotropes show eight-membered, puckered rings. Each sulfur atom bonds to each\n"]], ["block_4", ["of its two neighbors in the ring by covalent S-S single bonds. Here are (a) individual S8 rings, (b) S8 chains formed\nwhen the rings open, (c) longer chains formed by adding sulfur atoms to S8 chains, and (d) part of the very long\nsulfur chains formed at higher temperatures.\n"]], ["block_5", ["When rhombic sulfur melts, the straw-colored liquid is quite mobile; its viscosity is low because S8 molecules\nare essentially spherical and offer relatively little resistance as they move past each other. As the temperature\nrises, S-S bonds in the rings break, and polymeric chains of sulfur atoms result. These chains combine end to\nend, forming still longer chains that tangle with one another. The liquid gradually darkens in color and\nbecomes so viscous that finally (at about 230 \u00b0C) it does not pour easily. The dangling atoms at the ends of the\nchains of sulfur atoms are responsible for the dark red color because their electronic structure differs from\nthose of sulfur atoms that have bonds to two adjacent sulfur atoms. This causes them to absorb light differently\nand results in a different visible color. Cooling the liquid rapidly produces a rubberlike amorphous mass,\ncalled plastic sulfur.\n"]], ["block_6", ["Sulfur boils at 445 \u00b0C and forms a vapor consisting of S2, S6, and S8 molecules; at about 1000 \u00b0C, the vapor\ndensity corresponds to the formula S2, which is a paramagnetic molecule like O2 with a similar electronic\nstructure and a weak sulfur-sulfur double bond.\n"]], ["block_7", [" Access for free at openstax.org \n"]]], "page_898": [["block_0", ["As seen in this discussion, an important feature of the structural behavior of the nonmetals is that the\nelements usually occur with eight electrons in their valence shells. If necessary, the elements form enough\ncovalent bonds to supplement the electrons already present to possess an octet. For example, members of\ngroup 15 have five valence electrons and require only three additional electrons to fill their valence shells.\nThese elements form three covalent bonds in their free state: triple bonds in the N2 molecule or single bonds\nto three different atoms in arsenic and phosphorus. The elements of group 16 require only two additional\nelectrons. Oxygen forms a double bond in the O2 molecule, and sulfur, selenium, and tellurium form two single\nbonds in various rings and chains. The halogens form diatomic molecules in which each atom is involved in\nonly one bond. This provides the electron required necessary to complete the octet on the halogen atom. The\nnoble gases do not form covalent bonds to other noble gas atoms because they already have a filled outer shell.\n"]], ["block_1", [" 18.5 Occurrence, Preparation, and Compounds of Hydrogen \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["Hydrogen is the most abundant element in the universe. The sun and other stars are composed largely of\nhydrogen. Astronomers estimate that 90% of the atoms in the universe are hydrogen atoms. Hydrogen is a\ncomponent of more compounds than any other element. Water is the most abundant compound of hydrogen\nfound on earth. Hydrogen is an important part of petroleum, many minerals, cellulose and starch, sugar, fats,\noils, alcohols, acids, and thousands of other substances.\n"]], ["block_4", ["At ordinary temperatures, hydrogen is a colorless, odorless, tasteless, and nonpoisonous gas consisting of the\ndiatomic molecule H2. Hydrogen is composed of three isotopes, and unlike other elements, these isotopes have\ndifferent names and chemical symbols: protium, H, deuterium, H (or \u201cD\u201d), and tritium H (or \u201cT\u201d). In a\nnaturally occurring sample of hydrogen, there is one atom of deuterium for every 7000 H atoms and one atom\nof radioactive tritium for every 10H atoms. The chemical properties of the different isotopes are very similar\nbecause they have identical electron structures, but they differ in some physical properties because of their\ndiffering atomic masses. Elemental deuterium and tritium have lower vapor pressure than ordinary hydrogen.\nConsequently, when liquid hydrogen evaporates, the heavier isotopes are concentrated in the last portions to\nevaporate. Electrolysis of heavy water, D2O, yields deuterium. Most tritium originates from nuclear reactions.\n"]], ["block_5", [" Preparation of Hydrogen \n"]], ["block_6", ["Elemental hydrogen must be prepared from compounds by breaking chemical bonds. The most common\nmethods of preparing hydrogen follow.\n"]], ["block_7", [" From Steam and Carbon or Hydrocarbons \nWater is the cheapest and most abundant source of hydrogen. Passing steam over coke (an impure form of\nelemental carbon) at 1000 \u00b0C produces a mixture of carbon monoxide and hydrogen known as water gas:\n"]], ["block_8", ["Water gas is as an industrial fuel. It is possible to produce additional hydrogen by mixing the water gas with\nsteam in the presence of a catalyst to convert the CO to CO2. This reaction is the water gas shift reaction.\n"]], ["block_9", ["It is also possible to prepare a mixture of hydrogen and carbon monoxide by passing hydrocarbons from\nnatural gas or petroleum and steam over a nickel-based catalyst. Propane is an example of a hydrocarbon\nreactant:\n"]], ["block_10", [" Electrolysis \nHydrogen forms when direct current electricity passes through water containing an electrolyte such as H2SO4,\nas illustrated in Figure 18.26. Bubbles of hydrogen form at the cathode, and oxygen evolves at the anode. The\n"]], ["block_11", ["\u2022\nDescribe the properties, preparation, and compounds of hydrogen\n"]], ["block_12", [" 18.5 \u2022 Occurrence, Preparation, and Compounds of Hydrogen \n 885 \n"]]], "page_899": [["block_0", [" 886 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["net reaction is:\n"]], ["block_2", [" FIGURE 18.26 \nThe electrolysis of water produces hydrogen and oxygen. Because there are twice as many\n"]], ["block_3", ["hydrogen atoms as oxygen atoms and both elements are diatomic, there is twice the volume of hydrogen produced\nat the cathode as there is oxygen produced at the anode.\n"]], ["block_4", [" Reaction of Metals with Acids \nThis is the most convenient laboratory method of producing hydrogen. Metals with lower reduction potentials\nreduce the hydrogen ion in dilute acids to produce hydrogen gas and metal salts. For example, as shown in\nFigure 18.27, iron in dilute hydrochloric acid produces hydrogen gas and iron(II) chloride:\n"]], ["block_5", [" FIGURE 18.27 \nThe reaction of iron with an acid produces hydrogen. Here, iron reacts with hydrochloric acid.\n"]], ["block_6", ["(credit: Mark Ott)\n"]], ["block_7", [" Reaction of Ionic Metal Hydrides with Water \nIt is possible to produce hydrogen from the reaction of hydrides of the active metals, which contain the very\nstrongly basic Hanion, with water:\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", [{"image_0": "899_0.png", "coords": [90, 93, 522, 380]}]], ["block_10", [{"image_1": "899_1.png", "coords": [189, 504, 423, 660]}]]], "page_900": [["block_0", ["Metal hydrides are expensive but convenient sources of hydrogen, especially where space and weight are\nimportant factors. They are important in the inflation of life jackets, life rafts, and military balloons.\n"]], ["block_1", [" Reactions \n"]], ["block_2", ["Under normal conditions, hydrogen is relatively inactive chemically, but when heated, it enters into many\nchemical reactions.\n"]], ["block_3", ["Two thirds of the world\u2019s hydrogen production is devoted to the manufacture of ammonia, which is a fertilizer\nand used in the manufacture of nitric acid. Large quantities of hydrogen are also important in the process of\n hydrogenation , discussed in the chapter on organic chemistry.\n"]], ["block_4", ["It is possible to use hydrogen as a nonpolluting fuel. The reaction of hydrogen with oxygen is a very exothermic\nreaction, releasing 286 kJ of energy per mole of water formed. Hydrogen burns without explosion under\ncontrolled conditions. The oxygen-hydrogen torch, because of the high heat of combustion of hydrogen, can\nachieve temperatures up to 2800 \u00b0C. The hot flame of this torch is useful in cutting thick sheets of many\nmetals. Liquid hydrogen is also an important rocket fuel (Figure 18.28).\n"]], ["block_5", [" FIGURE 18.28 \nBefore the fleet\u2019s retirement in 2011, liquid hydrogen and liquid oxygen were used in the three\n"]], ["block_6", ["main engines of a space shuttle. Two compartments in the large tank held these liquids until the shuttle was\nlaunched. (credit: \u201creynermedia\u201d/Flickr)\n"]], ["block_7", ["An uncombined hydrogen atom consists of a nucleus and one valence electron in the 1s orbital. The n = 1\nvalence shell has a capacity for two electrons, and hydrogen can rightfully occupy two locations in the periodic\ntable. It is possible to consider hydrogen a group 1 element because hydrogen can lose an electron to form the\ncation, H. It is also possible to consider hydrogen to be a group 17 element because it needs only one electron\nto fill its valence orbital to form a hydride ion, H, or it can share an electron to form a single, covalent bond. In\nreality, hydrogen is a unique element that almost deserves its own location in the periodic table.\n"]], ["block_8", [" Reactions with Elements \nWhen heated, hydrogen reacts with the metals of group 1 and with Ca, Sr, and Ba (the more active metals in\ngroup 2). The compounds formed are crystalline, ionic hydrides that contain the hydride anion, H, a strong\nreducing agent and a strong base, which reacts vigorously with water and other acids to form hydrogen gas.\n"]], ["block_9", ["The reactions of hydrogen with nonmetals generally produce acidic hydrogen compounds with hydrogen in\nthe 1+ oxidation state. The reactions become more exothermic and vigorous as the electronegativity of the\nnonmetal increases. Hydrogen reacts with nitrogen and sulfur only when heated, but it reacts explosively with\nfluorine (forming HF) and, under some conditions, with chlorine (forming HCl). A mixture of hydrogen and\noxygen explodes if ignited. Because of the explosive nature of the reaction, it is necessary to exercise caution\nwhen handling hydrogen (or any other combustible gas) to avoid the formation of an explosive mixture in a\nconfined space. Although most hydrides of the nonmetals are acidic, ammonia and phosphine (PH3) are very,\nvery weak acids and generally function as bases. There is a summary of these reactions of hydrogen with the\nelements in Table 18.1.\n"]], ["block_10", [{"image_0": "900_0.png", "coords": [189, 273, 423, 423]}]], ["block_11", [" 18.5 \u2022 Occurrence, Preparation, and Compounds of Hydrogen \n 887 \n"]]], "page_901": [["block_0", [" 888 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", [" Reaction with Compounds \nHydrogen reduces the heated oxides of many metals, with the formation of the metal and water vapor. For\nexample, passing hydrogen over heated CuO forms copper and water.\n"]], ["block_2", ["Hydrogen may also reduce the metal ions in some metal oxides to lower oxidation states:\n"]], ["block_3", [" Hydrogen Compounds \n"]], ["block_4", ["Other than the noble gases, each of the nonmetals forms compounds with hydrogen. For brevity, we will\ndiscuss only a few hydrogen compounds of the nonmetals here.\n"]], ["block_5", [" Nitrogen Hydrogen Compounds \nAmmonia, NH3, forms naturally when any nitrogen-containing organic material decomposes in the absence of\nair. The laboratory preparation of ammonia is by the reaction of an ammonium salt with a strong base such as\nsodium hydroxide. The acid-base reaction with the weakly acidic ammonium ion gives ammonia, illustrated in\nFigure 18.29. Ammonia also forms when ionic nitrides react with water. The nitride ion is a much stronger\nbase than the hydroxide ion:\n"]], ["block_6", ["The commercial production of ammonia is by the direct combination of the elements in the Haber process :\n"]], ["block_7", ["Ammonia is a colorless gas with a sharp, pungent odor. Smelling salts utilize this powerful odor. Gaseous\nammonia readily liquefies to give a colorless liquid that boils at \u221233 \u00b0C. Due to intermolecular hydrogen\nbonding, the enthalpy of vaporization of liquid ammonia is higher than that of any other liquid except water, so\nammonia is useful as a refrigerant. Ammonia is quite soluble in water (658 L at STP dissolves in 1 L H2O).\n"]], ["block_8", ["The chemical properties of ammonia are as follows:\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", [" FIGURE 18.29 \nThe structure of ammonia is shown with a central nitrogen atom and three hydrogen atoms.\n"]], ["block_11", [" TABLE 18.1 \n"]], ["block_12", [" General Equation \n Comments \n"]], ["block_13", ["Chemical Reactions of Hydrogen with Other Elements\n"]], ["block_14", [{"image_0": "901_0.png", "coords": [247, 577, 364, 633]}]], ["block_15", ["ionic hydrides with group 1 and Ca, Sr, and Ba\n"]], ["block_16", ["requires high pressure and temperature; low yield\n"]], ["block_17", ["exothermic and potentially explosive\n"]], ["block_18", ["requires heating; low yield\n"]], ["block_19", ["X = F, Cl, Br, and I; explosive with F2; low yield with I2\n"]]], "page_902": [["block_0", [{"image_0": "902_0.png", "coords": [72, 240, 273, 308]}]], ["block_1", ["Chloramine, NH2Cl, results from the reaction of sodium hypochlorite, NaOCl, with ammonia in basic solution.\nIn the presence of a large excess of ammonia at low temperature, the chloramine reacts further to produce\nhydrazine, N2H4:\n"]], ["block_2", ["Anhydrous hydrazine is relatively stable in spite of its positive free energy of formation:\n"]], ["block_3", ["Hydrazine is a fuming, colorless liquid that has some physical properties remarkably similar to those of H2O (it\nmelts at 2 \u00b0C, boils at 113.5 \u00b0C, and has a density at 25 \u00b0C of 1.00 g/mL). It burns rapidly and completely in air\nwith substantial evolution of heat:\n"]], ["block_4", ["Like ammonia, hydrazine is both a Br\u00f8nsted base and a Lewis base, although it is weaker than ammonia. It\nreacts with strong acids and forms two series of salts that contain the\nand\nions, respectively.\n"]], ["block_5", ["Some rockets use hydrazine as a fuel.\n"]], ["block_6", [" Phosphorus Hydrogen Compounds \nThe most important hydride of phosphorus is phosphine, PH3, a gaseous analog of ammonia in terms of both\nformula and structure. Unlike ammonia, it is not possible to form phosphine by direct union of the elements.\nThere are two methods for the preparation of phosphine. One method is by the action of an acid on an ionic\nphosphide. The other method is the disproportionation of white phosphorus with hot concentrated base to\nproduce phosphine and the hydrogen phosphite ion:\n"]], ["block_7", ["Phosphine is a colorless, very poisonous gas, which has an odor like that of decaying fish. Heat easily\ndecomposes phosphine\nand the compound burns in air. The major uses of phosphine\n"]], ["block_8", ["are as a fumigant for grains and in semiconductor processing. Like ammonia, gaseous phosphine unites with\ngaseous hydrogen halides, forming phosphonium compounds like PH4Cl and PH4I. Phosphine is a much\nweaker base than ammonia; therefore, these compounds decompose in water, and the insoluble PH3 escapes\n"]], ["block_9", ["1.\nAmmonia acts as a Br\u00f8nsted base, as discussed in the chapter on acid-base chemistry. The ammonium\nion is similar in size to the potassium ion; compounds of the two ions exhibit many similarities in their\nstructures and solubilities.\n"]], ["block_10", ["2.\nAmmonia can display acidic behavior, although it is a much weaker acid than water. Like other acids,\nammonia reacts with metals, although it is so weak that high temperatures are necessary. Hydrogen and\n(depending on the stoichiometry) amides (salts of\nimides (salts of NH), or nitrides (salts of N)\n"]], ["block_11", ["3.\nThe nitrogen atom in ammonia has its lowest possible oxidation state (3\u2212) and thus is not susceptible to\nreduction. However, it can be oxidized. Ammonia burns in air, giving NO and water. Hot ammonia and the\nammonium ion are active reducing agents. Of particular interest are the oxidations of ammonium ion by\nnitrite ion,\nto yield pure nitrogen and by nitrate ion to yield nitrous oxide, N2O.\n"]], ["block_12", ["4.\nThere are a number of compounds that we can consider derivatives of ammonia through the replacement\nof one or more hydrogen atoms with some other atom or group of atoms. Inorganic derivations include\nchloramine, NH2Cl, and hydrazine, N2H4:\n"]], ["block_13", ["form.\n"]], ["block_14", [" 18.5 \u2022 Occurrence, Preparation, and Compounds of Hydrogen \n 889 \n"]]], "page_903": [["block_0", [" 890 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["from solution.\n"]], ["block_2", [" Sulfur Hydrogen Compounds \nHydrogen sulfide, H2S, is a colorless gas that is responsible for the offensive odor of rotten eggs and of many\nhot springs. Hydrogen sulfide is as toxic as hydrogen cyanide; therefore, it is necessary to exercise great care in\nhandling it. Hydrogen sulfide is particularly deceptive because it paralyzes the olfactory nerves; after a short\nexposure, one does not smell it.\n"]], ["block_3", ["The production of hydrogen sulfide by the direct reaction of the elements (H2 + S) is unsatisfactory because the\nyield is low. A more effective preparation method is the reaction of a metal sulfide with a dilute acid. For\nexample:\n"]], ["block_4", ["It is easy to oxidize the sulfur in metal sulfides and in hydrogen sulfide, making metal sulfides and H2S good\nreducing agents. In acidic solutions, hydrogen sulfide reduces Feto Fe,\nto Mn,\nto Cr,\n"]], ["block_5", ["and HNO3 to NO2. The sulfur in H2S usually oxidizes to elemental sulfur, unless a large excess of the oxidizing\nagent is present. In which case, the sulfide may oxidize to\nor\n(or to SO2 or SO3 in the absence of\n"]], ["block_6", ["water):\n"]], ["block_7", ["This oxidation process leads to the removal of the hydrogen sulfide found in many sources of natural gas. The\ndeposits of sulfur in volcanic regions may be the result of the oxidation of H2S present in volcanic gases.\n"]], ["block_8", ["Hydrogen sulfide is a weak diprotic acid that dissolves in water to form hydrosulfuric acid. The acid ionizes in\ntwo stages, yielding hydrogen sulfide ions, HS, in the first stage and sulfide ions, S, in the second. Since\nhydrogen sulfide is a weak acid, aqueous solutions of soluble sulfides and hydrogen sulfides are basic:\n"]], ["block_9", [" Halogen Hydrogen Compounds \nBinary compounds containing only hydrogen and a halogen are hydrogen halides . At room temperature, the\npure hydrogen halides HF, HCl, HBr, and HI are gases.\n"]], ["block_10", ["In general, it is possible to prepare the halides by the general techniques used to prepare other acids. Fluorine,\nchlorine, and bromine react directly with hydrogen to form the respective hydrogen halide. This is a\ncommercially important reaction for preparing hydrogen chloride and hydrogen bromide.\n"]], ["block_11", ["The acid-base reaction between a nonvolatile strong acid and a metal halide will yield a hydrogen halide. The\nescape of the gaseous hydrogen halide drives the reaction to completion. For example, the usual method of\npreparing hydrogen fluoride is by heating a mixture of calcium fluoride, CaF2, and concentrated sulfuric acid:\n"]], ["block_12", ["Gaseous hydrogen fluoride is also a by-product in the preparation of phosphate fertilizers by the reaction of\nfluoroapatite, Ca5(PO4)3F, with sulfuric acid. The reaction of concentrated sulfuric acid with a chloride salt\nproduces hydrogen chloride both commercially and in the laboratory.\n"]], ["block_13", ["In most cases, sodium chloride is the chloride of choice because it is the least expensive chloride. Hydrogen\nbromide and hydrogen iodide cannot be prepared using sulfuric acid because this acid is an oxidizing agent\ncapable of oxidizing both bromide and iodide. However, it is possible to prepare both hydrogen bromide and\nhydrogen iodide using an acid such as phosphoric acid because it is a weaker oxidizing agent. For example:\n"]], ["block_14", ["All of the hydrogen halides are very soluble in water, forming hydrohalic acids. With the exception of hydrogen\nfluoride, which has a strong hydrogen-fluoride bond, they are strong acids. Reactions of hydrohalic acids with\nmetals, metal hydroxides, oxides, or carbonates produce salts of the halides. Most chloride salts are soluble in\nwater. AgCl, PbCl2, and Hg2Cl2 are the commonly encountered exceptions.\n"]], ["block_15", [" Access for free at openstax.org \n"]]], "page_904": [["block_0", ["The halide ions give the substances the properties associated with X(aq). The heavier halide ions (Cl, Br, and\nI) can act as reducing agents, and the lighter halogens or other oxidizing agents will oxidize them:\n"]], ["block_1", ["For example, bromine oxidizes iodine:\n"]], ["block_2", ["Hydrofluoric acid is unique in its reactions with sand (silicon dioxide) and with glass, which is a mixture of\nsilicates:\n"]], ["block_3", ["The volatile silicon tetrafluoride escapes from these reactions. Because hydrogen fluoride attacks glass, it can\nfrost or etch glass and is used to etch markings on thermometers, burets, and other glassware.\n"]], ["block_4", ["The largest use for hydrogen fluoride is in production of hydrochlorofluorocarbons for refrigerants, in plastics,\nand in propellants. The second largest use is in the manufacture of cryolite, Na3AlF6, which is important in the\nproduction of aluminum. The acid is also important in the production of other inorganic fluorides (such as\nBF3), which serve as catalysts in the industrial synthesis of certain organic compounds.\n"]], ["block_5", ["Hydrochloric acid is relatively inexpensive. It is an important and versatile acid in industry and is important\nfor the manufacture of metal chlorides, dyes, glue, glucose, and various other chemicals. A considerable\namount is also important for the activation of oil wells and as pickle liquor\u2014an acid used to remove oxide\ncoating from iron or steel that is to be galvanized, tinned, or enameled. The amounts of hydrobromic acid and\nhydroiodic acid used commercially are insignificant by comparison.\n"]], ["block_6", [" 18.6 Occurrence, Preparation, and Properties of Carbonates \n"]], ["block_7", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_8", ["The chemistry of carbon is extensive; however, most of this chemistry is not relevant to this chapter. The other\naspects of the chemistry of carbon will appear in the chapter covering organic chemistry. In this chapter, we\nwill focus on the carbonate ion and related substances. The metals of groups 1 and 2, as well as zinc, cadmium,\nmercury, and lead(II), form ionic carbonates \u2014compounds that contain the carbonate anions,\nThe\n"]], ["block_9", ["metals of group 1, magnesium, calcium, strontium, and barium also form hydrogen carbonates \u2014compounds\nthat contain the hydrogen carbonate anion,\nalso known as the bicarbonate anion .\n"]], ["block_10", ["With the exception of magnesium carbonate, it is possible to prepare carbonates of the metals of groups 1 and\n2 by the reaction of carbon dioxide with the respective oxide or hydroxide. Examples of such reactions include:\n"]], ["block_11", ["The carbonates of the alkaline earth metals of group 12 and lead(II) are not soluble. These carbonates\nprecipitate upon mixing a solution of soluble alkali metal carbonate with a solution of soluble salts of these\nmetals. Examples of net ionic equations for the reactions are:\n"]], ["block_12", ["Pearls and the shells of most mollusks are calcium carbonate. Tin(II) or one of the trivalent or tetravalent ions\nsuch as Alor Snbehave differently in this reaction as carbon dioxide and the corresponding oxide form\n"]], ["block_13", ["\u2022\nDescribe the preparation, properties, and uses of some representative metal carbonates\n"]], ["block_14", [" 18.6 \u2022 Occurrence, Preparation, and Properties of Carbonates \n 891 \n"]]], "page_905": [["block_0", [" 892 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["instead of the carbonate.\n"]], ["block_2", ["Alkali metal hydrogen carbonates such as NaHCO3 and CsHCO3 form by saturating a solution of the hydroxides\nwith carbon dioxide. The net ionic reaction involves hydroxide ion and carbon dioxide:\n"]], ["block_3", ["It is possible to isolate the solids by evaporation of the water from the solution.\n"]], ["block_4", ["Although they are insoluble in pure water, alkaline earth carbonates dissolve readily in water containing\ncarbon dioxide because hydrogen carbonate salts form. For example, caves and sinkholes form in limestone\nwhen CaCO3 dissolves in water containing dissolved carbon dioxide:\n"]], ["block_5", ["Hydrogen carbonates of the alkaline earth metals remain stable only in solution; evaporation of the solution\nproduces the carbonate. Stalactites and stalagmites, like those shown in Figure 18.30, form in caves when\ndrops of water containing dissolved calcium hydrogen carbonate evaporate to leave a deposit of calcium\ncarbonate.\n"]], ["block_6", [" FIGURE 18.30 \n(a) Stalactites and (b) stalagmites are cave formations of calcium carbonate. (credit a: modification\n"]], ["block_7", ["of work by Arvind Govindaraj; credit b: modification of work by the National Park Service.)\n"]], ["block_8", ["The two carbonates used commercially in the largest quantities are sodium carbonate and calcium carbonate.\nIn the United States, sodium carbonate is extracted from the mineral trona, Na3(CO3)(HCO3)(H2O)2. Following\nrecrystallization to remove clay and other impurities, heating the recrystallized trona produces Na2CO3:\n"]], ["block_9", ["Carbonates are moderately strong bases. Aqueous solutions are basic because the carbonate ion accepts\nhydrogen ion from water in this reversible reaction:\n"]], ["block_10", ["Carbonates react with acids to form salts of the metal, gaseous carbon dioxide, and water. The reaction of\ncalcium carbonate, the active ingredient of the antacid Tums, with hydrochloric acid (stomach acid), as shown\nin Figure 18.31, illustrates the reaction:\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", [{"image_0": "905_0.png", "coords": [189, 265, 423, 448]}]]], "page_906": [["block_0", ["Other applications of carbonates include glass making\u2014where carbonate ions serve as a source of oxide\nions\u2014and synthesis of oxides.\n"]], ["block_1", ["Hydrogen carbonates are amphoteric because they act as both weak acids and weak bases. Hydrogen\ncarbonate ions act as acids and react with solutions of soluble hydroxides to form a carbonate and water:\n"]], ["block_2", ["With acids, hydrogen carbonates form a salt, carbon dioxide, and water. Baking soda (bicarbonate of soda or\nsodium bicarbonate) is sodium hydrogen carbonate. Baking powder contains baking soda and a solid acid\nsuch as potassium hydrogen tartrate (cream of tartar), KHC4H4O6. As long as the powder is dry, no reaction\noccurs; immediately after the addition of water, the acid reacts with the hydrogen carbonate ions to form\ncarbon dioxide:\n"]], ["block_3", ["Dough will trap the carbon dioxide, causing it to expand during baking, producing the characteristic texture of\nbaked goods.\n"]], ["block_4", [" 18.7 Occurrence, Preparation, and Properties of Nitrogen \n"]], ["block_5", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_6", ["Most pure nitrogen comes from the fractional distillation of liquid air. The atmosphere consists of 78%\nnitrogen by volume. This means there are more than 20 million tons of nitrogen over every square mile of the\nearth\u2019s surface. Nitrogen is a component of proteins and of the genetic material (DNA/RNA) of all plants and\nanimals.\n"]], ["block_7", ["Under ordinary conditions, nitrogen is a colorless, odorless, and tasteless gas. It boils at 77 K and freezes at 63\nK. Liquid nitrogen is a useful coolant because it is inexpensive and has a low boiling point. Nitrogen is very\nunreactive because of the very strong triple bond between the nitrogen atoms. The only common reactions at\nroom temperature occur with lithium to form Li3N, with certain transition metal complexes, and with\nhydrogen or oxygen in nitrogen-fixing bacteria. The general lack of reactivity of nitrogen makes the\nremarkable ability of some bacteria to synthesize nitrogen compounds using atmospheric nitrogen gas as the\nsource one of the most exciting chemical events on our planet. This process is one type of nitrogen fixation . In\nthis case, nitrogen fixation is the process where organisms convert atmospheric nitrogen into biologically\nuseful chemicals. Nitrogen fixation also occurs when lightning passes through air, causing molecular nitrogen\nto react with oxygen to form nitrogen oxides, which are then carried down to the soil.\n"]], ["block_8", ["\u2022\nDescribe the properties, preparation, and uses of nitrogen\n"]], ["block_9", [" FIGURE 18.31 \nThe reaction of calcium carbonate with hydrochloric acid is shown. (credit: Mark Ott)\n"]], ["block_10", [{"image_0": "906_0.png", "coords": [189, 57, 423, 213]}]], ["block_11", [" 18.7 \u2022 Occurrence, Preparation, and Properties of Nitrogen \n 893 \n"]]], "page_907": [["block_0", [" 894 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["Large volumes of atmospheric nitrogen are necessary for making ammonia\u2014the principal starting material\n"]], ["block_2", [" Access for free at openstax.org \n"]], ["block_3", ["Chemistry in Everyday Life\n"]], ["block_4", [" Nitrogen Fixation \nAll living organisms require nitrogen compounds for survival. Unfortunately, most of these organisms\ncannot absorb nitrogen from its most abundant source\u2014the atmosphere. Atmospheric nitrogen consists of\nN2 molecules, which are very unreactive due to the strong nitrogen-nitrogen triple bond. However, a few\norganisms can overcome this problem through a process known as nitrogen fixation, illustrated in Figure\n18.32.\n"]], ["block_5", [" FIGURE 18.32 \nAll living organisms require nitrogen. A few microorganisms are able to process atmospheric\n"]], ["block_6", ["nitrogen using nitrogen fixation. (credit \u201croots\u201d: modification of work by the United States Department of\nAgriculture; credit \u201croot nodules\u201d: modification of work by Louisa Howard)\n"]], ["block_7", ["Nitrogen fixation is the process where organisms convert atmospheric nitrogen into biologically useful\nchemicals. To date, the only known kind of biological organisms capable of nitrogen fixation are\nmicroorganisms. These organisms employ enzymes called nitrogenases, which contain iron and\nmolybdenum. Many of these microorganisms live in a symbiotic relationship with plants, with the best-\nknown example being the presence of rhizobia in the root nodules of legumes.\n"]], ["block_8", [{"image_0": "907_0.png", "coords": [90, 168, 521, 573]}]]], "page_908": [["block_0", ["used for preparation of large quantities of other nitrogen-containing compounds. Most other uses for\nelemental nitrogen depend on its inactivity. It is helpful when a chemical process requires an inert\natmosphere. Canned foods and luncheon meats cannot oxidize in a pure nitrogen atmosphere, so they retain a\nbetter flavor and color, and spoil less rapidly, when sealed in nitrogen instead of air. This technology allows\nfresh produce to be available year-round, regardless of growing season.\n"]], ["block_1", ["There are compounds with nitrogen in all of its oxidation states from 3\u2212 to 5+. Much of the chemistry of\nnitrogen involves oxidation-reduction reactions. Some active metals (such as alkali metals and alkaline earth\nmetals) can reduce nitrogen to form metal nitrides. In the remainder of this section, we will examine nitrogen-\noxygen chemistry.\n"]], ["block_2", ["There are well-characterized nitrogen oxides in which nitrogen exhibits each of its positive oxidation numbers\nfrom 1+ to 5+. When ammonium nitrate is carefully heated, nitrous oxide (dinitrogen oxide) and water vapor\nform. Stronger heating generates nitrogen gas, oxygen gas, and water vapor. No one should ever attempt this\nreaction\u2014it can be very explosive. In 1947, there was a major ammonium nitrate explosion in Texas City,\nTexas, and, in 2013, there was another major explosion in West, Texas. In the last 100 years, there were nearly\n30 similar disasters worldwide, resulting in the loss of numerous lives. In this oxidation-reduction reaction,\nthe nitrogen in the nitrate ion oxidizes the nitrogen in the ammonium ion. Nitrous oxide, shown in Figure\n18.33, is a colorless gas possessing a mild, pleasing odor and a sweet taste. It finds application as an anesthetic\nfor minor operations, especially in dentistry, under the name \u201claughing gas.\u201d\n"]], ["block_3", ["Low yields of nitric oxide, NO, form when heating nitrogen and oxygen together. NO also forms when lightning\npasses through air during thunderstorms. Burning ammonia is the commercial method of preparing nitric\noxide. In the laboratory, the reduction of nitric acid is the best method for preparing nitric oxide. When copper\nreacts with dilute nitric acid, nitric oxide is the principal reduction product:\n"]], ["block_4", ["Gaseous nitric oxide is the most thermally stable of the nitrogen oxides and is the simplest known thermally\nstable molecule with an unpaired electron. It is one of the air pollutants generated by internal combustion\nengines, resulting from the reaction of atmospheric nitrogen and oxygen during the combustion process.\n"]], ["block_5", ["At room temperature, nitric oxide is a colorless gas consisting of diatomic molecules. As is often the case with\nmolecules that contain an unpaired electron, two molecules combine to form a dimer by pairing their\nunpaired electrons to form a bond. Liquid and solid NO both contain N2O2 dimers, like that shown in Figure\n18.34. Most substances with unpaired electrons exhibit color by absorbing visible light; however, NO is\ncolorless because the absorption of light is not in the visible region of the spectrum.\n"]], ["block_6", ["Cooling a mixture of equal parts nitric oxide and nitrogen dioxide to \u221221 \u00b0C produces dinitrogen trioxide, a\nblue liquid consisting of N2O3 molecules (shown in Figure 18.35). Dinitrogen trioxide exists only in the liquid\nand solid states. When heated, it reverts to a mixture of NO and NO2.\n"]], ["block_7", [" FIGURE 18.33 \nNitrous oxide, N2O, is an anesthetic that has these molecular (left) and resonance (right) structures.\n"]], ["block_8", [" FIGURE 18.34 \nThis shows the equilibrium between NO and N2O2. The molecule, N2O2, absorbs light.\n"]], ["block_9", [{"image_0": "908_0.png", "coords": [130, 303, 481, 351]}]], ["block_10", [{"image_1": "908_1.png", "coords": [189, 559, 423, 612]}]], ["block_11", [" 18.7 \u2022 Occurrence, Preparation, and Properties of Nitrogen \n 895 \n"]]], "page_909": [["block_0", [" 896 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", [" FIGURE 18.35 \nDinitrogen trioxide, N2O3, only exists in liquid or solid states and has these molecular (left) and\n"]], ["block_2", ["resonance (right) structures.\n"]], ["block_3", ["It is possible to prepare nitrogen dioxide in the laboratory by heating the nitrate of a heavy metal, or by the\nreduction of concentrated nitric acid with copper metal, as shown in Figure 18.36. Commercially, it is possible\nto prepare nitrogen dioxide by oxidizing nitric oxide with air.\n"]], ["block_4", [" FIGURE 18.36 \nThe reaction of copper metal with concentrated HNO3 produces a solution of Cu(NO3)2 and brown\n"]], ["block_5", ["fumes of NO2. (credit: modification of work by Mark Ott)\n"]], ["block_6", ["The nitrogen dioxide molecule (illustrated in Figure 18.37) contains an unpaired electron, which is\nresponsible for its color and paramagnetism. It is also responsible for the dimerization of NO2. At low\npressures or at high temperatures, nitrogen dioxide has a deep brown color that is due to the presence of the\nNO2 molecule. At low temperatures, the color almost entirely disappears as dinitrogen tetraoxide, N2O4, forms.\nAt room temperature, an equilibrium exists:\n"]], ["block_7", [" FIGURE 18.37 \nThe molecular and resonance structures for nitrogen dioxide (NO2, left) and dinitrogen tetraoxide\n"]], ["block_8", ["(N2O4, right) are shown.\n"]], ["block_9", ["Dinitrogen pentaoxide, N2O5 (illustrated in Figure 18.38), is a white solid that is formed by the dehydration of\nnitric acid by phosphorus(V) oxide (tetraphosphorus decoxide):\n"]], ["block_10", ["It is unstable above room temperature, decomposing to N2O4 and O2.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", [{"image_0": "909_0.png", "coords": [130, 57, 481, 133]}]], ["block_13", [{"image_1": "909_1.png", "coords": [130, 212, 481, 334]}]], ["block_14", [{"image_2": "909_2.png", "coords": [155, 455, 456, 638]}]]], "page_910": [["block_0", [" FIGURE 18.38 \nThis image shows the molecular structure and one resonance structure of a molecule of dinitrogen\n"]], ["block_1", ["pentaoxide, N2O5.\n"]], ["block_2", ["The oxides of nitrogen(III), nitrogen(IV), and nitrogen(V) react with water and form nitrogen-containing\noxyacids. Nitrogen(III) oxide, N2O3, is the anhydride of nitrous acid; HNO2 forms when N2O3 reacts with water.\nThere are no stable oxyacids containing nitrogen with an oxidation state of 4+; therefore, nitrogen(IV) oxide,\nNO2, disproportionates in one of two ways when it reacts with water. In cold water, a mixture of HNO2 and\nHNO3 forms. At higher temperatures, HNO3 and NO will form. Nitrogen(V) oxide, N2O5, is the anhydride of\nnitric acid; HNO3 is produced when N2O5 reacts with water:\n"]], ["block_3", ["The nitrogen oxides exhibit extensive oxidation-reduction behavior. Nitrous oxide resembles oxygen in its\nbehavior when heated with combustible substances. N2O is a strong oxidizing agent that decomposes when\nheated to form nitrogen and oxygen. Because one-third of the gas liberated is oxygen, nitrous oxide supports\ncombustion better than air (one-fifth oxygen). A glowing splinter bursts into flame when thrust into a bottle of\nthis gas. Nitric oxide acts both as an oxidizing agent and as a reducing agent. For example:\n"]], ["block_4", ["Nitrogen dioxide (or dinitrogen tetraoxide) is a good oxidizing agent. For example:\n"]], ["block_5", [" 18.8 Occurrence, Preparation, and Properties of Phosphorus \n"]], ["block_6", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_7", ["The industrial preparation of phosphorus is by heating calcium phosphate, obtained from phosphate rock,\nwith sand and coke:\n"]], ["block_8", ["The phosphorus distills out of the furnace and is condensed into a solid or burned to form P4O10. The\npreparation of many other phosphorus compounds begins with P4O10. The acids and phosphates are useful as\nfertilizers and in the chemical industry. Other uses are in the manufacture of special alloys such as\nferrophosphorus and phosphor bronze. Phosphorus is important in making pesticides, matches, and some\nplastics. Phosphorus is an active nonmetal. In compounds, phosphorus usually occurs in oxidation states of\n3\u2212, 3+, and 5+. Phosphorus exhibits oxidation numbers that are unusual for a group 15 element in compounds\nthat contain phosphorus-phosphorus bonds; examples include diphosphorus tetrahydride, H2P-PH2, and\ntetraphosphorus trisulfide, P4S3, illustrated in Figure 18.39.\n"]], ["block_9", ["\u2022\nDescribe the properties, preparation, and uses of phosphorus\n"]], ["block_10", [{"image_0": "910_0.png", "coords": [163, 57, 448, 150]}]], ["block_11", [" 18.8 \u2022 Occurrence, Preparation, and Properties of Phosphorus \n 897 \n"]]], "page_911": [["block_0", [" 898 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", [" Phosphorus Oxygen Compounds \n"]], ["block_2", ["Phosphorus forms two common oxides, phosphorus(III) oxide (or tetraphosphorus hexaoxide), P4O6, and\nphosphorus(V) oxide (or tetraphosphorus decaoxide), P4O10, both shown in Figure 18.40. Phosphorus(III)\noxide is a white crystalline solid with a garlic-like odor. Its vapor is very poisonous. It oxidizes slowly in air and\ninflames when heated to 70 \u00b0C, forming P4O10. Phosphorus(III) oxide dissolves slowly in cold water to form\nphosphorous acid, H3PO3.\n"]], ["block_3", ["Phosphorus(V) oxide, P4O10, is a white powder that is prepared by burning phosphorus in excess oxygen. Its\nenthalpy of formation is very high (\u22122984 kJ), and it is quite stable and a very poor oxidizing agent. Dropping\nP4O10 into water produces a hissing sound, heat, and orthophosphoric acid:\n"]], ["block_4", ["Because of its great affinity for water, phosphorus(V) oxide is an excellent drying agent for gases and solvents,\nand for removing water from many compounds.\n"]], ["block_5", [" Phosphorus Halogen Compounds \n"]], ["block_6", ["Phosphorus will react directly with the halogens, forming trihalides, PX3, and pentahalides, PX5. The trihalides\nare much more stable than the corresponding nitrogen trihalides; nitrogen pentahalides do not form because\nof nitrogen\u2019s inability to form more than four bonds.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [" FIGURE 18.40 \nThis image shows the molecular structures of P4O6 (left) and P4O10 (right).\n"]], ["block_9", [{"image_0": "911_0.png", "coords": [130, 362, 481, 550]}]], ["block_10", [" FIGURE 18.39 \nP4S3 is a component of the heads of strike-anywhere matches.\n"]], ["block_11", [{"image_1": "911_1.png", "coords": [189, 57, 423, 251]}]]], "page_912": [["block_0", ["The chlorides PCl3 and PCl5, both shown in Figure 18.41, are the most important halides of phosphorus.\nPhosphorus trichloride is a colorless liquid that is prepared by passing chlorine over molten phosphorus.\nPhosphorus pentachloride is an off-white solid that is prepared by oxidizing the trichloride with excess\nchlorine. The pentachloride sublimes when warmed and forms an equilibrium with the trichloride and\nchlorine when heated.\n"]], ["block_1", ["Like most other nonmetal halides, both phosphorus chlorides react with an excess of water and yield hydrogen\nchloride and an oxyacid: PCl3 yields phosphorous acid H3PO3 and PCl5 yields phosphoric acid, H3PO4.\n"]], ["block_2", ["The pentahalides of phosphorus are Lewis acids because of the empty valence d orbitals of phosphorus. These\ncompounds readily react with halide ions (Lewis bases) to give the anion\nWhereas phosphorus\n"]], ["block_3", ["pentafluoride is a molecular compound in all states, X-ray studies show that solid phosphorus pentachloride is\nan ionic compound,\nas are phosphorus pentabromide,\n[Br], and phosphorus\n"]], ["block_4", ["pentaiodide,\n[I].\n"]], ["block_5", [" 18.9 Occurrence, Preparation, and Compounds of Oxygen \n"]], ["block_6", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_7", ["Oxygen is the most abundant element on the earth\u2019s crust. The earth\u2019s surface is composed of the crust,\natmosphere, and hydrosphere. About 50% of the mass of the earth\u2019s crust consists of oxygen (combined with\nother elements, principally silicon). Oxygen occurs as O2 molecules and, to a limited extent, as O3 (ozone)\nmolecules in air. It forms about 20% of the mass of the air. About 89% of water by mass consists of combined\noxygen. In combination with carbon, hydrogen, and nitrogen, oxygen is a large part of plants and animals.\n"]], ["block_8", ["Oxygen is a colorless, odorless, and tasteless gas at ordinary temperatures. It is slightly denser than air.\nAlthough it is only slightly soluble in water (49 mL of gas dissolves in 1 L at STP), oxygen\u2019s solubility is very\nimportant to aquatic life.\n"]], ["block_9", ["Most of the oxygen isolated commercially comes from air and the remainder from the electrolysis of water. The\nseparation of oxygen from air begins with cooling and compressing the air until it liquefies. As liquid air\nwarms, oxygen with its higher boiling point (90 K) separates from nitrogen, which has a lower boiling point (77\nK). It is possible to separate the other components of air at the same time based on differences in their boiling\npoints.\n"]], ["block_10", ["Oxygen is essential in combustion processes such as the burning of fuels. Plants and animals use the oxygen\nfrom the air in respiration. The administration of oxygen-enriched air is an important medical practice when a\npatient is receiving an inadequate supply of oxygen because of shock, pneumonia, or some other illness.\n"]], ["block_11", ["The chemical industry employs oxygen for oxidizing many substances. A significant amount of oxygen\nproduced commercially is important in the removal of carbon from iron during steel production. Large\nquantities of pure oxygen are also necessary in metal fabrication and in the cutting and welding of metals with\n"]], ["block_12", ["\u2022\nDescribe the properties, preparation, and compounds of oxygen\n"]], ["block_13", ["\u2022\nDescribe the preparation, properties, and uses of some representative metal oxides, peroxides, and hydroxides\n"]], ["block_14", [" FIGURE 18.41 \nThis image shows the molecular structure of PCl3 (left) and PCl5 (right) in the gas phase.\n"]], ["block_15", [{"image_0": "912_0.png", "coords": [130, 126, 481, 266]}]], ["block_16", [" 18.9 \u2022 Occurrence, Preparation, and Compounds of Oxygen \n 899 \n"]]], "page_913": [["block_0", [" 900 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["oxyhydrogen and oxyacetylene torches.\n"]], ["block_2", ["Liquid oxygen is important to the space industry. It is an oxidizing agent in rocket engines. It is also the source\nof gaseous oxygen for life support in space.\n"]], ["block_3", ["As we know, oxygen is very important to life. The energy required for the maintenance of normal body\nfunctions in human beings and in other organisms comes from the slow oxidation of chemical compounds.\nOxygen is the final oxidizing agent in these reactions. In humans, oxygen passes from the lungs into the blood,\nwhere it combines with hemoglobin, producing oxyhemoglobin. In this form, blood transports the oxygen to\ntissues, where it is transferred to the tissues. The ultimate products are carbon dioxide and water. The blood\ncarries the carbon dioxide through the veins to the lungs, where the blood releases the carbon dioxide and\ncollects another supply of oxygen. Digestion and assimilation of food regenerate the materials consumed by\noxidation in the body; the energy liberated is the same as if the food burned outside the body.\n"]], ["block_4", ["Green plants continually replenish the oxygen in the atmosphere by a process called photosynthesis . The\nproducts of photosynthesis may vary, but, in general, the process converts carbon dioxide and water into\nglucose (a sugar) and oxygen using the energy of light:\n"]], ["block_5", ["Thus, the oxygen that became carbon dioxide and water by the metabolic processes in plants and animals\nreturns to the atmosphere by photosynthesis.\n"]], ["block_6", ["When dry oxygen is passed between two electrically charged plates, ozone (O3, illustrated in Figure 18.42), an\nallotrope of oxygen possessing a distinctive odor, forms. The formation of ozone from oxygen is an\nendothermic reaction, in which the energy comes from an electrical discharge, heat, or ultraviolet light:\n"]], ["block_7", ["The sharp odor associated with sparking electrical equipment is due, in part, to ozone.\n"]], ["block_8", [" FIGURE 18.42 \nThe image shows the bent ozone (O3) molecule and the resonance structures necessary to describe\n"]], ["block_9", ["its bonding.\n"]], ["block_10", ["Ozone forms naturally in the upper atmosphere by the action of ultraviolet light from the sun on the oxygen\nthere. Most atmospheric ozone occurs in the stratosphere, a layer of the atmosphere extending from about 10\nto 50 kilometers above the earth\u2019s surface. This ozone acts as a barrier to harmful ultraviolet light from the sun\nby absorbing it via a chemical decomposition reaction:\n"]], ["block_11", ["The reactive oxygen atoms recombine with molecular oxygen to complete the ozone cycle. The presence of\nstratospheric ozone decreases the frequency of skin cancer and other damaging effects of ultraviolet radiation.\nIt has been clearly demonstrated that chlorofluorocarbons, CFCs (known commercially as Freons), which were\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", [{"image_0": "913_0.png", "coords": [189, 439, 422, 578]}]]], "page_914": [["block_0", ["present as aerosol propellants in spray cans and as refrigerants, caused depletion of ozone in the stratosphere.\nThis occurred because ultraviolet light also causes CFCs to decompose, producing atomic chlorine. The\nchlorine atoms react with ozone molecules, resulting in a net removal of O3 molecules from stratosphere. This\nprocess is explored in detail in our coverage of chemical kinetics. There is a worldwide effort to reduce the\namount of CFCs used commercially, and the ozone hole is already beginning to decrease in size as atmospheric\nconcentrations of atomic chlorine decrease. While ozone in the stratosphere helps protect us, ozone in the\ntroposphere is a problem. This ozone is a toxic component of photochemical smog.\n"]], ["block_1", ["The uses of ozone depend on its reactivity with other substances. It can be used as a bleaching agent for oils,\nwaxes, fabrics, and starch: It oxidizes the colored compounds in these substances to colorless compounds. It is\nan alternative to chlorine as a disinfectant for water.\n"]], ["block_2", [" Reactions \n"]], ["block_3", ["Elemental oxygen is a strong oxidizing agent. It reacts with most other elements and many compounds.\n"]], ["block_4", [" Reaction with Elements \nOxygen reacts directly at room temperature or at elevated temperatures with all other elements except the\nnoble gases, the halogens, and few second- and third-row transition metals of low reactivity (those with higher\nreduction potentials than copper). Rust is an example of the reaction of oxygen with iron. The more active\nmetals form peroxides or superoxides. Less active metals and the nonmetals give oxides. Two examples of\nthese reactions are:\n"]], ["block_5", ["The oxides of halogens, at least one of the noble gases, and metals with higher reduction potentials than\ncopper do not form by the direct action of the elements with oxygen.\n"]], ["block_6", [" Reaction with Compounds \nElemental oxygen also reacts with some compounds. If it is possible to oxidize any of the elements in a given\ncompound, further oxidation by oxygen can occur. For example, hydrogen sulfide, H2S, contains sulfur with an\noxidation state of 2\u2212. Because the sulfur does not exhibit its maximum oxidation state, we would expect H2S to\nreact with oxygen. It does, yielding water and sulfur dioxide. The reaction is:\n"]], ["block_7", ["It is also possible to oxidize oxides such as CO and P4O6 that contain an element with a lower oxidation state.\nThe ease with which elemental oxygen picks up electrons is mirrored by the difficulty of removing electrons\nfrom oxygen in most oxides. Of the elements, only the very reactive fluorine can oxidize oxides to form oxygen\ngas.\n"]], ["block_8", [" Oxides, Peroxides, and Hydroxides \n"]], ["block_9", ["Compounds of the representative metals with oxygen fall into three categories: (1) oxides , containing oxide\nions, O; (2) peroxides , containing peroxides ions,\nwith oxygen-oxygen covalent single bonds and a\n"]], ["block_10", ["very limited number of superoxides , containing superoxide ions,\nwith oxygen-oxygen covalent bonds\n"]], ["block_11", ["that have a bond order of\nIn addition, there are (3) hydroxides , containing hydroxide ions, OH. All\n"]], ["block_12", ["representative metals form oxides. Some of the metals of group 2 also form peroxides, MO2, and the metals of\ngroup 1 also form peroxides, M2O2, and superoxides, MO2.\n"]], ["block_13", [" Oxides \nIt is possible to produce the oxides of most representative metals by heating the corresponding hydroxides\n(forming the oxide and gaseous water) or carbonates (forming the oxide and gaseous CO2). Equations for\nexample reactions are:\n"]], ["block_14", [" 18.9 \u2022 Occurrence, Preparation, and Compounds of Oxygen \n 901 \n"]]], "page_915": [["block_0", [" 902 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["The oxides of the alkali metals have little industrial utility, unlike magnesium oxide, calcium oxide, and\naluminum oxide. Magnesium oxide is important in making firebrick, crucibles, furnace linings, and thermal\ninsulation\u2014applications that require chemical and thermal stability. Calcium oxide, sometimes called\nquicklime or lime in the industrial market, is very reactive, and its principal uses reflect its reactivity. Pure\ncalcium oxide emits an intense white light when heated to a high temperature (as illustrated in Figure 18.43).\nBlocks of calcium oxide heated by gas flames were the stage lights in theaters before electricity was available.\nThis is the source of the phrase \u201cin the limelight.\u201d\n"]], ["block_2", ["However, alkali metal salts generally are very stable and do not decompose easily when heated. Alkali metal\noxides result from the oxidation-reduction reactions created by heating nitrates or hydroxides with the metals.\nEquations for sample reactions are:\n"]], ["block_3", ["With the exception of mercury(II) oxide, it is possible to produce the oxides of the metals of groups 2\u201315 by\nburning the corresponding metal in air. The heaviest member of each group, the member for which the inert\npair effect is most pronounced, forms an oxide in which the oxidation state of the metal ion is two less than the\ngroup oxidation state (inert pair effect). Thus, Tl2O, PbO, and Bi2O3 form when burning thallium, lead, and\nbismuth, respectively. The oxides of the lighter members of each group exhibit the group oxidation state. For\nexample, SnO2 forms from burning tin. Mercury(II) oxide, HgO, forms slowly when mercury is warmed below\n500 \u00b0C; it decomposes at higher temperatures.\n"]], ["block_4", ["Burning the members of groups 1 and 2 in air is not a suitable way to form the oxides of these elements. These\nmetals are reactive enough to combine with nitrogen in the air, so they form mixtures of oxides and ionic\nnitrides. Several also form peroxides or superoxides when heated in air.\n"]], ["block_5", ["Ionic oxides all contain the oxide ion, a very powerful hydrogen ion acceptor. With the exception of the very\ninsoluble aluminum oxide, Al2O3, tin(IV), SnO2, and lead(IV), PbO2, the oxides of the representative metals\nreact with acids to form salts. Some equations for these reactions are:\n"]], ["block_6", ["The oxides of the metals of groups 1 and 2 and of thallium(I) oxide react with water and form hydroxides.\nExamples of such reactions are:\n"]], ["block_7", [" FIGURE 18.43 \nCalcium oxide has many industrial uses. When it is heated at high temperatures, it emits an intense\n"]], ["block_8", ["white light.\n"]], ["block_9", ["Calcium oxide and calcium hydroxide are inexpensive bases used extensively in chemical processing,\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [{"image_0": "915_0.png", "coords": [130, 556, 481, 684]}]]], "page_916": [["block_0", ["although most of the useful products prepared from them do not contain calcium. Calcium oxide, CaO, is made\nby heating calcium carbonate, CaCO3, which is widely and inexpensively available as limestone or oyster\nshells:\n"]], ["block_1", ["Although this decomposition reaction is reversible, it is possible to obtain a 100% yield of CaO by allowing the\nCO2 to escape. It is possible to prepare calcium hydroxide by the familiar acid-base reaction of a soluble metal\noxide with water:\n"]], ["block_2", ["Both CaO and Ca(OH)2 are useful as bases; they accept protons and neutralize acids.\n"]], ["block_3", ["Alumina (Al2O3) occurs in nature as the mineral corundum, a very hard substance used as an abrasive for\ngrinding and polishing. Corundum is important to the jewelry trade as ruby and sapphire. The color of ruby is\ndue to the presence of a small amount of chromium; other impurities produce the wide variety of colors\npossible for sapphires. Artificial rubies and sapphires are now manufactured by melting aluminum oxide\n(melting point = 2050 \u00b0C) with small amounts of oxides to produce the desired colors and cooling the melt in\nsuch a way as to produce large crystals. Ruby lasers use synthetic ruby crystals.\n"]], ["block_4", ["Zinc oxide, ZnO, was a useful white paint pigment; however, pollutants tend to discolor the compound. The\ncompound is also important in the manufacture of automobile tires and other rubber goods, and in the\npreparation of medicinal ointments. For example, zinc-oxide-based sunscreens, as shown in Figure 18.44,\nhelp prevent sunburn. The zinc oxide in these sunscreens is present in the form of very small grains known as\nnanoparticles. Lead dioxide is a constituent of charged lead storage batteries. Lead(IV) tends to revert to the\nmore stable lead(II) ion by gaining two electrons, so lead dioxide is a powerful oxidizing agent.\n"]], ["block_5", [" Peroxides and Superoxides \nPeroxides and superoxides are strong oxidizers and are important in chemical processes. Hydrogen peroxide,\nH2O2, prepared from metal peroxides, is an important bleach and disinfectant. Peroxides and superoxides\nform when the metal or metal oxides of groups 1 and 2 react with pure oxygen at elevated temperatures.\nSodium peroxide and the peroxides of calcium, strontium, and barium form by heating the corresponding\nmetal or metal oxide in pure oxygen:\n"]], ["block_6", ["The peroxides of potassium, rubidium, and cesium can be prepared by heating the metal or its oxide in a\ncarefully controlled amount of oxygen:\n"]], ["block_7", ["With an excess of oxygen, the superoxides KO2, RbO2, and CsO2 form. For example:\n"]], ["block_8", [" FIGURE 18.44 \nZinc oxide protects exposed skin from sunburn. (credit: modification of work by \"osseous\"/Flickr)\n"]], ["block_9", [{"image_0": "916_0.png", "coords": [247, 361, 364, 482]}]], ["block_10", [" 18.9 \u2022 Occurrence, Preparation, and Compounds of Oxygen \n 903 \n"]]], "page_917": [["block_0", [" 904 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["The stability of the peroxides and superoxides of the alkali metals increases as the size of the cation increases.\n"]], ["block_2", [" Hydroxides \n Hydroxides are compounds that contain the OH\u2212 ion. It is possible to prepare these compounds by two general\ntypes of reactions. Soluble metal hydroxides can be produced by the reaction of the metal or metal oxide with\nwater. Insoluble metal hydroxides form when a solution of a soluble salt of the metal combines with a solution\ncontaining hydroxide ions.\n"]], ["block_3", ["With the exception of beryllium and magnesium, the metals of groups 1 and 2 react with water to form\nhydroxides and hydrogen gas. Examples of such reactions include:\n"]], ["block_4", ["However, these reactions can be violent and dangerous; therefore, it is preferable to produce soluble metal\nhydroxides by the reaction of the respective oxide with water:\n"]], ["block_5", ["Most metal oxides are base anhydrides . This is obvious for the soluble oxides because they form metal\nhydroxides. Most other metal oxides are insoluble and do not form hydroxides in water; however, they are still\nbase anhydrides because they will react with acids.\n"]], ["block_6", ["It is possible to prepare the insoluble hydroxides of beryllium, magnesium, and other representative metals by\nthe addition of sodium hydroxide to a solution of a salt of the respective metal. The net ionic equations for the\nreactions involving a magnesium salt, an aluminum salt, and a zinc salt are:\n"]], ["block_7", ["An excess of hydroxide must be avoided when preparing aluminum, gallium, zinc, and tin(II) hydroxides, or\nthe hydroxides will dissolve with the formation of the corresponding complex ions:\n"]], ["block_8", ["they form by a Lewis acid-base reaction with the metal being the Lewis acid.\n"]], ["block_9", [" FIGURE 18.45 \n(a) Mixing solutions of NaOH and Zn(NO3)2 produces a white precipitate of Zn(OH)2. (b) Addition of\n"]], ["block_10", ["an excess of NaOH results in dissolution of the precipitate. (credit: modification of work by Mark Ott)\n"]], ["block_11", ["Industry uses large quantities of sodium hydroxide as a cheap, strong base. Sodium chloride is the starting\nmaterial for the production of NaOH because NaCl is a less expensive starting material than the oxide. Sodium\nhydroxide is among the top 10 chemicals in production in the United States, and this production was almost\nentirely by electrolysis of solutions of sodium chloride. This process is the chlor-alkali process , and it is the\nprimary method for producing chlorine.\n"]], ["block_12", ["Sodium hydroxide is an ionic compound and melts without decomposition. It is very soluble in water, giving off\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", ["and\n(see Figure 18.45). The important aspect of complex ions for this chapter is that\n"]], ["block_15", [{"image_0": "917_0.png", "coords": [130, 482, 481, 607]}]]], "page_918": [["block_0", ["a great deal of heat and forming very basic solutions: 40 grams of sodium hydroxide dissolves in only 60 grams\nof water at 25 \u00b0C. Sodium hydroxide is employed in the production of other sodium compounds and is used to\nneutralize acidic solutions during the production of other chemicals such as petrochemicals and polymers.\n"]], ["block_1", ["Many of the applications of hydroxides are for the neutralization of acids (such as the antacid shown in Figure\n18.46) and for the preparation of oxides by thermal decomposition. An aqueous suspension of magnesium\nhydroxide constitutes the antacid milk of magnesia. Because of its ready availability (from the reaction of water\nwith calcium oxide prepared by the decomposition of limestone, CaCO3), low cost, and activity, calcium\nhydroxide is used extensively in commercial applications needing a cheap, strong base. The reaction of\nhydroxides with appropriate acids is also used to prepare salts.\n"]], ["block_2", [" FIGURE 18.46 \nCalcium carbonate, CaCO3, can be consumed in the form of an antacid to neutralize the effects of\n"]], ["block_3", ["acid in your stomach. (credit: \u201cMidnightcomm\u201d/Wikimedia Commons)\n"]], ["block_4", ["Chemistry in Everyday Life\n"]], ["block_5", [" The Chlor-Alkali Process \nAlthough they are very different chemically, there is a link between chlorine and sodium hydroxide\nbecause there is an important electrochemical process that produces the two chemicals simultaneously.\nThe process known as the chlor-alkali process, utilizes sodium chloride, which occurs in large deposits in\nmany parts of the world. This is an electrochemical process to oxidize chloride ion to chlorine and generate\nsodium hydroxide.\n"]], ["block_6", ["Passing a direct current of electricity through a solution of NaCl causes the chloride ions to migrate to the\npositive electrode where oxidation to gaseous chlorine occurs when the ion gives up an electron to the\nelectrode:\n"]], ["block_7", ["The electrons produced travel through the outside electrical circuit to the negative electrode. Although the\npositive sodium ions migrate toward this negative electrode, metallic sodium does not form because\nsodium ions are too difficult to reduce under the conditions used. (Recall that metallic sodium is active\nenough to react with water and hence, even if produced, would immediately react with water to produce\nsodium ions again.) Instead, water molecules pick up electrons from the electrode and undergo reduction\nto form hydrogen gas and hydroxide ions:\n"]], ["block_8", [{"image_0": "918_0.png", "coords": [130, 183, 481, 417]}]], ["block_9", [" 18.9 \u2022 Occurrence, Preparation, and Compounds of Oxygen \n 905 \n"]]], "page_919": [["block_0", [" 906 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", [" Nonmetal Oxygen Compounds \n"]], ["block_2", ["Most nonmetals react with oxygen to form nonmetal oxides. Depending on the available oxidation states for the\nelement, a variety of oxides might form. Fluorine will combine with oxygen to form fluorides such as OF2,\nwhere the oxygen has a 2+-oxidation state.\n"]], ["block_3", [" Sulfur Oxygen Compounds \nThe two common oxides of sulfur are sulfur dioxide, SO2, and sulfur trioxide, SO3. The odor of burning sulfur\ncomes from sulfur dioxide. Sulfur dioxide, shown in Figure 18.47, occurs in volcanic gases and in the\natmosphere near industrial plants that burn fuel containing sulfur compounds.\n"]], ["block_4", ["Commercial production of sulfur dioxide is from either burning sulfur or roasting sulfide ores such as ZnS,\nFeS2, and Cu2S in air. (Roasting, which forms the metal oxide, is the first step in the separation of many metals\nfrom their ores.) A convenient method for preparing sulfur dioxide in the laboratory is by the action of a strong\nacid on either sulfite salts containing the\nion or hydrogen sulfite salts containing\nSulfurous\n"]], ["block_5", ["acid, H2SO3, forms first, but quickly decomposes into sulfur dioxide and water. Sulfur dioxide also forms when\nmany reducing agents react with hot, concentrated sulfuric acid. Sulfur trioxide forms slowly when heating\nsulfur dioxide and oxygen together, and the reaction is exothermic:\n"]], ["block_6", ["Sulfur dioxide is a gas at room temperature, and the SO2 molecule is bent. Sulfur trioxide melts at 17 \u00b0C and\nboils at 43 \u00b0C. In the vapor state, its molecules are single SO3 units (shown in Figure 18.48), but in the solid\nstate, SO3 exists in several polymeric forms.\n"]], ["block_7", [" FIGURE 18.48 \nThis image shows the structure (top) of sulfur trioxide in the gas phase and its resonance forms\n"]], ["block_8", ["(bottom).\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["The overall result is the conversion of the aqueous solution of NaCl to an aqueous solution of NaOH,\ngaseous Cl2, and gaseous H2:\n"]], ["block_11", [" FIGURE 18.47 \nThis image shows the molecular structure (left) and resonance forms (right) of sulfur dioxide.\n"]], ["block_12", [{"image_0": "919_0.png", "coords": [130, 273, 481, 337]}]], ["block_13", [{"image_1": "919_1.png", "coords": [130, 515, 481, 693]}]]], "page_920": [["block_0", ["The sulfur oxides react as Lewis acids with many oxides and hydroxides in Lewis acid-base reactions, with the\nformation of sulfites or hydrogen sulfites , and sulfates or hydrogen sulfates , respectively.\n"]], ["block_1", [" Halogen Oxygen Compounds \nThe halogens do not react directly with oxygen, but it is possible to prepare binary oxygen-halogen compounds\nby the reactions of the halogens with oxygen-containing compounds. Oxygen compounds with chlorine,\nbromine, and iodine are oxides because oxygen is the more electronegative element in these compounds. On\nthe other hand, fluorine compounds with oxygen are fluorides because fluorine is the more electronegative\nelement.\n"]], ["block_2", ["As a class, the oxides are extremely reactive and unstable, and their chemistry has little practical importance.\nDichlorine oxide, formally called dichlorine monoxide, and chlorine dioxide, both shown in Figure 18.49, are\nthe only commercially important compounds. They are important as bleaching agents (for use with pulp and\nflour) and for water treatment.\n"]], ["block_3", [" Nonmetal Oxyacids and Their Salts \n"]], ["block_4", ["Nonmetal oxides form acids when allowed to react with water; these are acid anhydrides. The resulting\noxyanions can form salts with various metal ions.\n"]], ["block_5", [" Nitrogen Oxyacids and Salts \n"]], ["block_6", ["Nitrogen pentaoxide, N2O5, and NO2 react with water to form nitric acid, HNO3. Alchemists, as early as the\neighth century, knew nitric acid (shown in Figure 18.50) as aqua fortis (meaning \"strong water\"). The acid was\nuseful in the separation of gold from silver because it dissolves silver but not gold. Traces of nitric acid occur in\nthe atmosphere after thunderstorms, and its salts are widely distributed in nature. There are tremendous\ndeposits of Chile saltpeter, NaNO3, in the desert region near the boundary of Chile and Peru. Bengal saltpeter,\nKNO3, occurs in India and in other countries of the Far East.\n"]], ["block_7", ["In the laboratory, it is possible to produce nitric acid by heating a nitrate salt (such as sodium or potassium\nnitrate) with concentrated sulfuric acid:\n"]], ["block_8", ["The Ostwald process is the commercial method for producing nitric acid. This process involves the oxidation\nof ammonia to nitric oxide, NO; oxidation of nitric oxide to nitrogen dioxide, NO2; and further oxidation and\nhydration of nitrogen dioxide to form nitric acid:\n"]], ["block_9", [" FIGURE 18.50 \nThis image shows the molecular structure (left) of nitric acid, HNO3 and its resonance forms (right).\n"]], ["block_10", [" FIGURE 18.49 \nThis image shows the structures of the (a) Cl2O and (b) ClO2 molecules.\n"]], ["block_11", [{"image_0": "920_0.png", "coords": [130, 496, 481, 590]}]], ["block_12", [{"image_1": "920_1.png", "coords": [189, 228, 423, 321]}]], ["block_13", [" 18.9 \u2022 Occurrence, Preparation, and Compounds of Oxygen \n 907 \n"]]], "page_921": [["block_0", [" 908 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["Or\n"]], ["block_2", ["Pure nitric acid is a colorless liquid. However, it is often yellow or brown in color because NO2 forms as the acid\ndecomposes. Nitric acid is stable in aqueous solution; solutions containing 68% of the acid are commercially\navailable concentrated nitric acid. It is both a strong oxidizing agent and a strong acid.\n"]], ["block_3", ["The action of nitric acid on a metal rarely produces H2 (by reduction of H) in more than small amounts.\nInstead, the reduction of nitrogen occurs. The products formed depend on the concentration of the acid, the\nactivity of the metal, and the temperature. Normally, a mixture of nitrates, nitrogen oxides, and various\nreduction products form. Less active metals such as copper, silver, and lead reduce concentrated nitric acid\nprimarily to nitrogen dioxide. The reaction of dilute nitric acid with copper produces NO. In each case, the\nnitrate salts of the metals crystallize upon evaporation of the resultant solutions.\n"]], ["block_4", ["Nonmetallic elements, such as sulfur, carbon, iodine, and phosphorus, undergo oxidation by concentrated\nnitric acid to their oxides or oxyacids, with the formation of NO2:\n"]], ["block_5", ["Nitric acid oxidizes many compounds; for example, concentrated nitric acid readily oxidizes hydrochloric acid\nto chlorine and chlorine dioxide. A mixture of one part concentrated nitric acid and three parts concentrated\nhydrochloric acid (called aqua regia, which means royal water) reacts vigorously with metals. This mixture is\nparticularly useful in dissolving gold, platinum, and other metals that are more difficult to oxidize than\nhydrogen. A simplified equation to represent the action of aqua regia on gold is:\n"]], ["block_6", ["Although gold is generally unreactive, you can watch a video (http://openstax.org/l/16gold) of the complex\nmixture of compounds present in aqua regia dissolving it into solution.\n"]], ["block_7", [" Nitrates , salts of nitric acid, form when metals, oxides, hydroxides, or carbonates react with nitric acid. Most\nnitrates are soluble in water; indeed, one of the significant uses of nitric acid is to prepare soluble metal\nnitrates.\n"]], ["block_8", ["Nitric acid finds extensive use in the laboratory and in chemical industries as a strong acid and strong\noxidizing agent. It is important in the manufacture of explosives, dyes, plastics, and drugs. Salts of nitric acid\n(nitrates) are valuable as fertilizers. Gunpowder is a mixture of potassium nitrate, sulfur, and charcoal.\n"]], ["block_9", ["The reaction of N2O3 with water gives a pale blue solution of nitrous acid, HNO2. However, HNO2 (shown in\nFigure 18.51) is easier to prepare by the addition of an acid to a solution of nitrite; nitrous acid is a weak acid,\nso the nitrite ion is basic in aqueous solution:\n"]], ["block_10", ["Nitrous acid is very unstable and exists only in solution. It disproportionates slowly at room temperature\n(rapidly when heated) into nitric acid and nitric oxide. Nitrous acid is an active oxidizing agent with strong\nreducing agents, and strong oxidizing agents oxidize it to nitric acid.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["LINK TO LEARNING\n"]]], "page_922": [["block_0", ["Sodium nitrite, NaNO2, is an additive to meats such as hot dogs and cold cuts. The nitrite ion has two functions.\nIt limits the growth of bacteria that can cause food poisoning, and it prolongs the meat\u2019s retention of its red\ncolor. The addition of sodium nitrite to meat products is controversial because nitrous acid reacts with certain\norganic compounds to form a class of compounds known as nitrosamines. Nitrosamines produce cancer in\nlaboratory animals. This has prompted the FDA to limit the amount of NaNO2 in foods.\n"]], ["block_1", ["The nitrites are much more stable than the acid, but nitrites, like nitrates, can explode. Nitrites, like nitrates,\nare also soluble in water (AgNO2 is only slightly soluble).\n"]], ["block_2", [" Phosphorus Oxyacids and Salts \n"]], ["block_3", ["Pure orthophosphoric acid, H3PO4 (shown in Figure 18.52), forms colorless, deliquescent crystals that melt at\n42 \u00b0C. The common name of this compound is phosphoric acid, and is commercially available as a viscous\n82% solution known as syrupy phosphoric acid. One use of phosphoric acid is as an additive to many soft\ndrinks.\n"]], ["block_4", ["One commercial method of preparing orthophosphoric acid is to treat calcium phosphate rock with\nconcentrated sulfuric acid:\n"]], ["block_5", [" FIGURE 18.52 \nOrthophosphoric acid, H3PO4, is colorless when pure and has this molecular (left) and Lewis\n"]], ["block_6", ["structure (right).\n"]], ["block_7", ["Dilution of the products with water, followed by filtration to remove calcium sulfate, gives a dilute acid solution\ncontaminated with calcium dihydrogen phosphate, Ca(H2PO4)2, and other compounds associated with calcium\nphosphate rock. It is possible to prepare pure orthophosphoric acid by dissolving P4O10 in water.\n"]], ["block_8", ["The action of water on P4O6, PCl3, PBr3, or PI3 forms phosphorous acid, H3PO3 (shown in Figure 18.53). The\nbest method for preparing pure phosphorous acid is by hydrolyzing phosphorus trichloride:\n"]], ["block_9", ["Heating the resulting solution expels the hydrogen chloride and leads to the evaporation of water. When\nsufficient water evaporates, white crystals of phosphorous acid will appear upon cooling. The crystals are\ndeliquescent, very soluble in water, and have an odor like that of garlic. The solid melts at 70.1 \u00b0C and\ndecomposes at about 200 \u00b0C by disproportionation into phosphine and orthophosphoric acid:\n"]], ["block_10", [" FIGURE 18.51 \nThis image shows the molecular structure of a molecule of nitrous acid, HNO2.\n"]], ["block_11", [{"image_0": "922_0.png", "coords": [130, 399, 481, 508]}]], ["block_12", [{"image_1": "922_1.png", "coords": [189, 57, 422, 151]}]], ["block_13", [" 18.9 \u2022 Occurrence, Preparation, and Compounds of Oxygen \n 909 \n"]]], "page_923": [["block_0", [" 910 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", [" FIGURE 18.53 \nIn a molecule of phosphorous acid, H3PO3, only the two hydrogen atoms bonded to an oxygen atom\n"]], ["block_2", ["are acidic.\n"]], ["block_3", ["Phosphorous acid forms only two series of salts, which contain the dihydrogen phosphite ion,\nor the\n"]], ["block_4", ["hydrogen phosphate ion,\nrespectively. It is not possible to replace the third atom of hydrogen\n"]], ["block_5", ["because it is not very acidic, as it is not easy to ionize the P-H bond.\n"]], ["block_6", [" Sulfur Oxyacids and Salts \n"]], ["block_7", ["The preparation of sulfuric acid, H2SO4 (shown in Figure 18.54), begins with the oxidation of sulfur to sulfur\ntrioxide and then converting the trioxide to sulfuric acid. Pure sulfuric acid is a colorless, oily liquid that\nfreezes at 10.5 \u00b0C. It fumes when heated because the acid decomposes to water and sulfur trioxide. The heating\nprocess causes the loss of more sulfur trioxide than water, until reaching a concentration of 98.33% acid. Acid\nof this concentration boils at 338 \u00b0C without further change in concentration (a constant boiling solution) and\nis commercially concentrated H2SO4. The amount of sulfuric acid used in industry exceeds that of any other\nmanufactured compound.\n"]], ["block_8", ["The strong affinity of concentrated sulfuric acid for water makes it a good dehydrating agent. It is possible to\ndry gases and immiscible liquids that do not react with the acid by passing them through the acid.\n"]], ["block_9", ["Sulfuric acid is a strong diprotic acid that ionizes in two stages. In aqueous solution, the first stage is\nessentially complete. The secondary ionization is not nearly so complete, and\nis a moderately strong\n"]], ["block_10", ["acid (about 25% ionized in solution of a\nsalt: Ka = 1.2\n10).\n"]], ["block_11", ["Being a diprotic acid, sulfuric acid forms both sulfates, such as Na2SO4, and hydrogen sulfates, such as\nNaHSO4. Most sulfates are soluble in water; however, the sulfates of barium, strontium, calcium, and lead are\nonly slightly soluble in water.\n"]], ["block_12", ["Among the important sulfates are Na2SO4\u22c510H2O and Epsom salts, MgSO4\u22c57H2O. Because the\nion is an\n"]], ["block_13", ["acid, hydrogen sulfates, such as NaHSO4, exhibit acidic behavior, and this compound is the primary ingredient\nin some household cleansers.\n"]], ["block_14", ["Hot, concentrated sulfuric acid is an oxidizing agent. Depending on its concentration, the temperature, and the\nstrength of the reducing agent, sulfuric acid oxidizes many compounds and, in the process, undergoes\nreduction to SO2,\nS, H2S, or S.\n"]], ["block_15", ["Sulfur dioxide dissolves in water to form a solution of sulfurous acid, as expected for the oxide of a nonmetal.\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", [" FIGURE 18.54 \nSulfuric acid has a tetrahedral molecular structure.\n"]], ["block_18", [{"image_0": "923_0.png", "coords": [189, 329, 423, 485]}]], ["block_19", [{"image_1": "923_1.png", "coords": [189, 57, 422, 135]}]]], "page_924": [["block_0", ["Sulfurous acid is unstable, and it is not possible to isolate anhydrous H2SO3. Heating a solution of sulfurous\nacid expels the sulfur dioxide. Like other diprotic acids, sulfurous acid ionizes in two steps: The hydrogen\nsulfite ion,\nand the sulfite ion,\nform. Sulfurous acid is a moderately strong acid. Ionization is\n"]], ["block_1", ["about 25% in the first stage, but it is much less in the second (Ka1 = 1.2\n10and Ka2 = 6.2\n10).\n"]], ["block_2", ["In order to prepare solid sulfite and hydrogen sulfite salts, it is necessary to add a stoichiometric amount of a\nbase to a sulfurous acid solution and then evaporate the water. These salts also form from the reaction of SO2\nwith oxides and hydroxides. Heating solid sodium hydrogen sulfite forms sodium sulfite, sulfur dioxide, and\nwater:\n"]], ["block_3", ["Strong oxidizing agents can oxidize sulfurous acid. Oxygen in the air oxidizes it slowly to the more stable\nsulfuric acid:\n"]], ["block_4", ["Solutions of sulfites are also very susceptible to air oxidation to produce sulfates. Thus, solutions of sulfites\nalways contain sulfates after exposure to air.\n"]], ["block_5", [" Halogen Oxyacids and Their Salts \n"]], ["block_6", ["The compounds HXO, HXO2, HXO3, and HXO4, where X represents Cl, Br, or I, are the hypohalous, halous, halic,\nand perhalic acids, respectively. The strengths of these acids increase from the hypohalous acids, which are\nvery weak acids, to the perhalic acids, which are very strong. Table 18.2 lists the known acids, and, where\nknown, their pKa values are given in parentheses.\n"]], ["block_7", ["The only known oxyacid of fluorine is the very unstable hypofluorous acid, HOF, which is prepared by the\nreaction of gaseous fluorine with ice:\n"]], ["block_8", ["The compound is very unstable and decomposes above \u221240 \u00b0C. This compound does not ionize in water, and\nthere are no known salts. It is uncertain whether the name hypofluorous acid is even appropriate for HOF; a\nmore appropriate name might be hydrogen hypofluorite.\n"]], ["block_9", ["The reactions of chlorine and bromine with water are analogous to that of fluorine with ice, but these reactions\ndo not go to completion, and mixtures of the halogen and the respective hypohalous and hydrohalic acids\nresult. Other than HOF, the hypohalous acids only exist in solution. The hypohalous acids are all very weak\nacids; however, HOCl is a stronger acid than HOBr, which, in turn, is stronger than HOI.\n"]], ["block_10", ["The addition of base to solutions of the hypohalous acids produces solutions of salts containing the basic\n"]], ["block_11", [" TABLE 18.2 \n"]], ["block_12", [" Name \n Fluorine \n Chlorine \n Bromine \n Iodine \n"]], ["block_13", ["hypohalous\nHOF\nHOCl (7.5)\nHOBr (8.7)\nHOI (11)\n"]], ["block_14", ["halous\nHClO2 (2.0)\n"]], ["block_15", ["halic\nHClO3\nHBrO3\nHIO3 (0.8)\n"]], ["block_16", ["perhalic\nHClO4\nHBrO4\nHIO4 (1.6)\n"]], ["block_17", ["paraperhalic\nH5IO6 (1.6)\n"]], ["block_18", ["Oxyacids of the Halogens\n"]], ["block_19", [" 18.9 \u2022 Occurrence, Preparation, and Compounds of Oxygen \n 911 \n"]]], "page_925": [["block_0", [" 912 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["hypohalite ions, OX. It is possible to isolate these salts as solids. All of the hypohalites are unstable with\nrespect to disproportionation in solution, but the reaction is slow for hypochlorite. Hypobromite and\nhypoiodite disproportionate rapidly, even in the cold:\n"]], ["block_2", ["Sodium hypochlorite is an inexpensive bleach (Clorox) and germicide. The commercial preparation involves\nthe electrolysis of cold, dilute, aqueous sodium chloride solutions under conditions where the resulting\nchlorine and hydroxide ion can react. The net reaction is:\n"]], ["block_3", ["The only definitely known halous acid is chlorous acid, HClO2, obtained by the reaction of barium chlorite with\ndilute sulfuric acid:\n"]], ["block_4", ["Filtering the insoluble barium sulfate leaves a solution of HClO2. Chlorous acid is not stable; it slowly\ndecomposes in solution to yield chlorine dioxide, hydrochloric acid, and water. Chlorous acid reacts with bases\nto give salts containing the chlorite ion (shown in Figure 18.55). Sodium chlorite finds an extensive application\nin the bleaching of paper because it is a strong oxidizing agent and does not damage the paper.\n"]], ["block_5", ["Chloric acid, HClO3, and bromic acid, HBrO3, are stable only in solution. The reaction of iodine with\nconcentrated nitric acid produces stable white iodic acid, HIO3:\n"]], ["block_6", ["It is possible to obtain the lighter halic acids from their barium salts by reaction with dilute sulfuric acid. The\nreaction is analogous to that used to prepare chlorous acid. All of the halic acids are strong acids and very\nactive oxidizing agents. The acids react with bases to form salts containing chlorate ions (shown in Figure\n18.56). Another preparative method is the electrochemical oxidation of a hot solution of a metal halide to form\nthe appropriate metal chlorates. Sodium chlorate is a weed killer; potassium chlorate is used as an oxidizing\nagent.\n"]], ["block_7", ["Perchloric acid, HClO4, forms when treating a perchlorate, such as potassium perchlorate, with sulfuric acid\nunder reduced pressure. The HClO4 can be distilled from the mixture:\n"]], ["block_8", ["Dilute aqueous solutions of perchloric acid are quite stable thermally, but concentrations above 60% are\nunstable and dangerous. Perchloric acid and its salts are powerful oxidizing agents, as the very electronegative\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", [" FIGURE 18.55 \nChlorite ions,\nare produced when chlorous acid reacts with bases.\n"]], ["block_11", [" FIGURE 18.56 \nChlorate ions,\nare produced when halic acids react with bases.\n"]], ["block_12", [{"image_0": "925_0.png", "coords": [130, 293, 481, 381]}]], ["block_13", [{"image_1": "925_1.png", "coords": [130, 533, 481, 631]}]]], "page_926": [["block_0", ["chlorine is more stable in a lower oxidation state than 7+. Serious explosions have occurred when heating\nconcentrated solutions with easily oxidized substances. However, its reactions as an oxidizing agent are slow\nwhen perchloric acid is cold and dilute. The acid is among the strongest of all acids. Most salts containing the\nperchlorate ion (shown in Figure 18.57) are soluble. It is possible to prepare them from reactions of bases with\nperchloric acid and, commercially, by the electrolysis of hot solutions of their chlorides.\n"]], ["block_1", [" FIGURE 18.57 \nPerchlorate ions,\ncan be produced when perchloric acid reacts with a base or by\n"]], ["block_2", ["electrolysis of hot solutions of their chlorides.\n"]], ["block_3", ["Perbromate salts are difficult to prepare, and the best syntheses currently involve the oxidation of bromates in\nbasic solution with fluorine gas followed by acidification. There are few, if any, commercial uses of this acid or\nits salts.\n"]], ["block_4", ["There are several different acids containing iodine in the 7+-oxidation state; they include metaperiodic acid,\nHIO4, and paraperiodic acid, H5IO6. These acids are strong oxidizing agents and react with bases to form the\nappropriate salts.\n"]], ["block_5", [" 18.10 Occurrence, Preparation, and Properties of Sulfur \n"]], ["block_6", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_7", ["Sulfur exists in nature as elemental deposits as well as sulfides of iron, zinc, lead, and copper, and sulfates of\nsodium, calcium, barium, and magnesium. Hydrogen sulfide is often a component of natural gas and occurs in\nmany volcanic gases, like those shown in Figure 18.58. Sulfur is a constituent of many proteins and is essential\nfor life.\n"]], ["block_8", ["The Frasch process , illustrated in Figure 18.59, is important in the mining of free sulfur from enormous\n"]], ["block_9", ["\u2022\nDescribe the properties, preparation, and uses of sulfur\n"]], ["block_10", [" FIGURE 18.58 \nVolcanic gases contain hydrogen sulfide. (credit: Daniel Julie/Wikimedia Commons)\n"]], ["block_11", [{"image_0": "926_0.png", "coords": [130, 449, 481, 691]}]], ["block_12", [{"image_1": "926_1.png", "coords": [204, 126, 407, 203]}]], ["block_13", [" 18.10 \u2022 Occurrence, Preparation, and Properties of Sulfur \n 913 \n"]]], "page_927": [["block_0", [" 914 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["underground deposits in Texas and Louisiana. Superheated water (170 \u00b0C and 10 atm pressure) is forced down\nthe outermost of three concentric pipes to the underground deposit. The hot water melts the sulfur. The\ninnermost pipe conducts compressed air into the liquid sulfur. The air forces the liquid sulfur, mixed with air,\nto flow up through the outlet pipe. Transferring the mixture to large settling vats allows the solid sulfur to\nseparate upon cooling. This sulfur is 99.5% to 99.9% pure and requires no purification for most uses.\n"]], ["block_2", ["Larger amounts of sulfur also come from hydrogen sulfide recovered during the purification of natural gas.\n"]], ["block_3", ["Sulfur exists in several allotropic forms. The stable form at room temperature contains eight-membered rings,\nand so the true formula is S8. However, chemists commonly use S to simplify the coefficients in chemical\nequations; we will follow this practice in this book.\n"]], ["block_4", ["Like oxygen, which is also a member of group 16, sulfur exhibits a distinctly nonmetallic behavior. It oxidizes\nmetals, giving a variety of binary sulfides in which sulfur exhibits a negative oxidation state (2\u2212). Elemental\nsulfur oxidizes less electronegative nonmetals, and more electronegative nonmetals, such as oxygen and the\nhalogens, will oxidize it. Other strong oxidizing agents also oxidize sulfur. For example, concentrated nitric\nacid oxidizes sulfur to the sulfate ion, with the concurrent formation of nitrogen(IV) oxide:\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", [" FIGURE 18.59 \nThe Frasch process is used to mine sulfur from underground deposits.\n"]], ["block_7", [{"image_0": "927_0.png", "coords": [189, 126, 423, 584]}]]], "page_928": [["block_0", ["The chemistry of sulfur with an oxidation state of 2\u2212 is similar to that of oxygen. Unlike oxygen, however, sulfur\nforms many compounds in which it exhibits positive oxidation states.\n"]], ["block_1", [" 18.11 Occurrence, Preparation, and Properties of Halogens \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["The elements in group 17 are the halogens. These are the elements fluorine, chlorine, bromine, iodine, and\nastatine. These elements are too reactive to occur freely in nature, but their compounds are widely distributed.\nChlorides are the most abundant; although fluorides, bromides, and iodides are less common, they are\nreasonably available. In this section, we will examine the occurrence, preparation, and properties of halogens.\nNext, we will examine halogen compounds with the representative metals followed by an examination of the\ninterhalogens. This section will conclude with some applications of halogens.\n"]], ["block_4", [" Occurrence and Preparation \n"]], ["block_5", ["All of the halogens occur in seawater as halide ions. The concentration of the chloride ion is 0.54 M; that of the\nother halides is less than 10M. Fluoride also occurs in minerals such as CaF2, Ca(PO4)3F, and Na3AlF6.\nChloride also occurs in the Great Salt Lake and the Dead Sea, and in extensive salt beds that contain NaCl, KCl,\nor MgCl2. Part of the chlorine in your body is present as hydrochloric acid, which is a component of stomach\nacid. Bromine compounds occur in the Dead Sea and underground brines. Iodine compounds are found in\nsmall quantities in Chile saltpeter, underground brines, and sea kelp. Iodine is essential to the function of the\nthyroid gland.\n"]], ["block_6", ["The best sources of halogens (except iodine) are halide salts. It is possible to oxidize the halide ions to free\ndiatomic halogen molecules by various methods, depending on the ease of oxidation of the halide ion. Fluoride\nis the most difficult to oxidize, whereas iodide is the easiest.\n"]], ["block_7", ["The major method for preparing fluorine is electrolytic oxidation. The most common electrolysis procedure is\nto use a molten mixture of potassium hydrogen fluoride, KHF2, and anhydrous hydrogen fluoride. Electrolysis\ncauses HF to decompose, forming fluorine gas at the anode and hydrogen at the cathode. It is necessary to\nkeep the two gases separated to prevent their explosive recombination to reform hydrogen fluoride.\n"]], ["block_8", ["Most commercial chlorine comes from the electrolysis of the chloride ion in aqueous solutions of sodium\nchloride; this is the chlor-alkali process discussed previously. Chlorine is also a product of the electrolytic\nproduction of metals such as sodium, calcium, and magnesium from their fused chlorides. It is also possible to\nprepare chlorine by the chemical oxidation of the chloride ion in acid solution with strong oxidizing agents\nsuch as manganese dioxide (MnO2) or sodium dichromate (Na2Cr2O7). The reaction with manganese dioxide is:\n"]], ["block_9", ["The commercial preparation of bromine involves the oxidation of bromide ion by chlorine:\n"]], ["block_10", ["Chlorine is a stronger oxidizing agent than bromine. This method is important for the production of essentially\nall domestic bromine.\n"]], ["block_11", ["Some iodine comes from the oxidation of iodine chloride, ICl, or iodic acid, HlO3. The commercial preparation\nof iodine utilizes the reduction of sodium iodate, NaIO3, an impurity in deposits of Chile saltpeter, with sodium\nhydrogen sulfite:\n"]], ["block_12", ["\u2022\nDescribe the preparation, properties, and uses of halogens\n"]], ["block_13", ["\u2022\nDescribe the properties, preparation, and uses of halogen compounds\n"]], ["block_14", [" 18.11 \u2022 Occurrence, Preparation, and Properties of Halogens \n 915 \n"]]], "page_929": [["block_0", [" 916 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", [" Properties of the Halogens \n"]], ["block_2", ["Fluorine is a pale yellow gas, chlorine is a greenish-yellow gas, bromine is a deep reddish-brown liquid, and\niodine is a grayish-black crystalline solid. Liquid bromine has a high vapor pressure, and the reddish vapor is\nreadily visible in Figure 18.60. Iodine crystals have a noticeable vapor pressure. When gently heated, these\ncrystals sublime and form a beautiful deep violet vapor.\n"]], ["block_3", [" FIGURE 18.60 \nChlorine is a pale yellow-green gas (left), gaseous bromine is deep orange (center), and gaseous\n"]], ["block_4", ["iodine is purple (right). (Fluorine is so reactive that it is too dangerous to handle.) (credit: Sahar Atwa)\n"]], ["block_5", ["Bromine is only slightly soluble in water, but it is miscible in all proportions in less polar (or nonpolar) solvents\nsuch as chloroform, carbon tetrachloride, and carbon disulfide, forming solutions that vary from yellow to\nreddish-brown, depending on the concentration.\n"]], ["block_6", ["Iodine is soluble in chloroform, carbon tetrachloride, carbon disulfide, and many hydrocarbons, giving violet\nsolutions of I2 molecules. Iodine dissolves only slightly in water, giving brown solutions. It is quite soluble in\naqueous solutions of iodides, with which it forms brown solutions. These brown solutions result because\niodine molecules have empty valence d orbitals and can act as weak Lewis acids towards the iodide ion. The\nequation for the reversible reaction of iodine (Lewis acid) with the iodide ion (Lewis base) to form triiodide ion,\n"]], ["block_7", ["The easier it is to oxidize the halide ion, the more difficult it is for the halogen to act as an oxidizing agent.\nFluorine generally oxidizes an element to its highest oxidation state, whereas the heavier halogens may not.\nFor example, when excess fluorine reacts with sulfur, SF6 forms. Chlorine gives SCl2 and bromine, S2Br2.\nIodine does not react with sulfur.\n"]], ["block_8", ["Fluorine is the most powerful oxidizing agent of the known elements. It spontaneously oxidizes most other\nelements; therefore, the reverse reaction, the oxidation of fluorides, is very difficult to accomplish. Fluorine\nreacts directly and forms binary fluorides with all of the elements except the lighter noble gases (He, Ne, and\nAr). Fluorine is such a strong oxidizing agent that many substances ignite on contact with it. Drops of water\ninflame in fluorine and form O2, OF2, H2O2, O3, and HF. Wood and asbestos ignite and burn in fluorine gas.\nMost hot metals burn vigorously in fluorine. However, it is possible to handle fluorine in copper, iron, or nickel\ncontainers because an adherent film of the fluoride salt passivates their surfaces. Fluorine is the only element\nthat reacts directly with the noble gas xenon.\n"]], ["block_9", ["Although it is a strong oxidizing agent, chlorine is less active than fluorine. Mixing chlorine and hydrogen in\nthe dark makes the reaction between them to be imperceptibly slow. Exposure of the mixture to light causes\nthe two to react explosively. Chlorine is also less active towards metals than fluorine, and oxidation reactions\nusually require higher temperatures. Molten sodium ignites in chlorine. Chlorine attacks most nonmetals (C,\nN2, and O2 are notable exceptions), forming covalent molecular compounds. Chlorine generally reacts with\ncompounds that contain only carbon and hydrogen (hydrocarbons) by adding to multiple bonds or by\nsubstitution.\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["is:\n"]], ["block_12", [{"image_0": "929_0.png", "coords": [189, 134, 423, 287]}]]], "page_930": [["block_0", ["In cold water, chlorine undergoes a disproportionation reaction:\n"]], ["block_1", ["Half the chlorine atoms oxidize to the 1+ oxidation state (hypochlorous acid), and the other half reduce to the\n1\u2212 oxidation state (chloride ion). This disproportionation is incomplete, so chlorine water is an equilibrium\nmixture of chlorine molecules, hypochlorous acid molecules, hydronium ions, and chloride ions. When\nexposed to light, this solution undergoes a photochemical decomposition:\n"]], ["block_2", ["The nonmetal chlorine is more electronegative than any other element except fluorine, oxygen, and nitrogen.\nIn general, very electronegative elements are good oxidizing agents; therefore, we would expect elemental\nchlorine to oxidize all of the other elements except for these three (and the nonreactive noble gases). Its\noxidizing property, in fact, is responsible for its principal use. For example, phosphorus(V) chloride, an\nimportant intermediate in the preparation of insecticides and chemical weapons, is manufactured by\noxidizing the phosphorus with chlorine:\n"]], ["block_3", ["A great deal of chlorine is also used to oxidize, and thus to destroy, organic or biological materials in water\npurification and in bleaching.\n"]], ["block_4", ["The chemical properties of bromine are similar to those of chlorine, although bromine is the weaker oxidizing\nagent and its reactivity is less than that of chlorine.\n"]], ["block_5", ["Iodine is the least reactive of the halogens. It is the weakest oxidizing agent, and the iodide ion is the most\neasily oxidized halide ion. Iodine reacts with metals, but heating is often required. It does not oxidize other\nhalide ions.\n"]], ["block_6", ["Compared with the other halogens, iodine reacts only slightly with water. Traces of iodine in water react with a\nmixture of starch and iodide ion, forming a deep blue color. This reaction is a very sensitive test for the\npresence of iodine in water.\n"]], ["block_7", [" Halides of the Representative Metals \n"]], ["block_8", ["Thousands of salts of the representative metals have been prepared. The binary halides are an important\nsubclass of salts. A salt is an ionic compound composed of cations and anions, other than hydroxide or oxide\nions. In general, it is possible to prepare these salts from the metals or from oxides, hydroxides, or carbonates.\nWe will illustrate the general types of reactions for preparing salts through reactions used to prepare binary\nhalides.\n"]], ["block_9", ["The binary compounds of a metal with the halogens are the halides . Most binary halides are ionic. However,\nmercury, the elements of group 13 with oxidation states of 3+, tin(IV), and lead(IV) form covalent binary\nhalides.\n"]], ["block_10", ["The direct reaction of a metal and a halogen produce the halide of the metal. Examples of these oxidation-\nreduction reactions include:\n"]], ["block_11", ["Reactions of the alkali metals with elemental halogens are very exothermic and often quite violent. Under\ncontrolled conditions, they provide exciting demonstrations for budding students of chemistry. You can view\nthe initial heating (http://openstax.org/l/16sodium) of the sodium that removes the coating of sodium\nhydroxide, sodium peroxide, and residual mineral oil to expose the reactive surface. The reaction with\nchlorine gas then proceeds very nicely.\n"]], ["block_12", ["LINK TO LEARNING\n"]], ["block_13", [" 18.11 \u2022 Occurrence, Preparation, and Properties of Halogens \n 917 \n"]]], "page_931": [["block_0", [" 918 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["If a metal can exhibit two oxidation states, it may be necessary to control the stoichiometry in order to obtain\nthe halide with the lower oxidation state. For example, preparation of tin(II) chloride requires a 1:1 ratio of Sn\nto Cl2, whereas preparation of tin(IV) chloride requires a 1:2 ratio:\n"]], ["block_2", ["The active representative metals\u2014those that are easier to oxidize than hydrogen\u2014react with gaseous hydrogen\nhalides to produce metal halides and hydrogen. The reaction of zinc with hydrogen fluoride is:\n"]], ["block_3", ["The active representative metals also react with solutions of hydrogen halides to form hydrogen and solutions\nof the corresponding halides. Examples of such reactions include:\n"]], ["block_4", ["Hydroxides, carbonates, and some oxides react with solutions of the hydrogen halides to form solutions of\nhalide salts. It is possible to prepare additional salts by the reaction of these hydroxides, carbonates, and\noxides with aqueous solution of other acids:\n"]], ["block_5", ["A few halides and many of the other salts of the representative metals are insoluble. It is possible to prepare\nthese soluble salts by metathesis reactions that occur when solutions of soluble salts are mixed (see Figure\n18.61). Metathesis reactions are examined in the chapter on the stoichiometry of chemical reactions.\n"]], ["block_6", ["Several halides occur in large quantities in nature. The ocean and underground brines contain many halides.\nFor example, magnesium chloride in the ocean is the source of magnesium ions used in the production of\nmagnesium. Large underground deposits of sodium chloride, like the salt mine shown in Figure 18.62, occur\nin many parts of the world. These deposits serve as the source of sodium and chlorine in almost all other\ncompounds containing these elements. The chlor-alkali process is one example.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [" FIGURE 18.61 \nSolid HgI2 forms when solutions of KI and Hg(NO3)2 are mixed. (credit: Sahar Atwa)\n"]], ["block_9", [{"image_0": "931_0.png", "coords": [189, 370, 423, 545]}]]], "page_932": [["block_0", [" FIGURE 18.62 \nUnderground deposits of sodium chloride are found throughout the world and are often mined. This\n"]], ["block_1", ["is a tunnel in the K\u0142odawa salt mine in Poland. (credit: Jarek Zok)\n"]], ["block_2", [" Interhalogens \n"]], ["block_3", ["Compounds formed from two or more different halogens are interhalogens . Interhalogen molecules consist of\none atom of the heavier halogen bonded by single bonds to an odd number of atoms of the lighter halogen. The\nstructures of IF3, IF5, and IF7 are illustrated in Figure 18.63. Formulas for other interhalogens, each of which\ncomes from the reaction of the respective halogens, are in Table 18.3.\n"]], ["block_4", [{"image_0": "932_0.png", "coords": [72, 414, 540, 573]}]], ["block_5", [" FIGURE 18.63 \nThe structure of IF3 is T-shaped (left), IF5 is square pyramidal (center), and IF7 is pentagonal\n"]], ["block_6", ["bipyramidal (right).\n"]], ["block_7", ["Note from Table 18.3 that fluorine is able to oxidize iodine to its maximum oxidation state, 7+, whereas\nbromine and chlorine, which are more difficult to oxidize, achieve only the 5+-oxidation state. A 7+-oxidation\nstate is the limit for the halogens. Because smaller halogens are grouped about a larger one, the maximum\nnumber of smaller atoms possible increases as the radius of the larger atom increases. Many of these\ncompounds are unstable, and most are extremely reactive. The interhalogens react like their component\nhalides; halogen fluorides, for example, are stronger oxidizing agents than are halogen chlorides.\n"]], ["block_8", ["The ionic polyhalides of the alkali metals, such as KI3, KICl2, KICl4, CsIBr2, and CsBrCl2, which contain an\nanion composed of at least three halogen atoms, are closely related to the interhalogens. As seen previously,\nthe formation of the polyhalide anion\nis responsible for the solubility of iodine in aqueous solutions\n"]], ["block_9", [{"image_1": "932_1.png", "coords": [130, 57, 481, 303]}]], ["block_10", [" 18.11 \u2022 Occurrence, Preparation, and Properties of Halogens \n 919 \n"]]], "page_933": [["block_0", [" 920 \n 18 \u2022 Representative Metals, Metalloids, and Nonmetals \n"]], ["block_1", ["containing an iodide ion.\n"]], ["block_2", [" Applications \n"]], ["block_3", ["The fluoride ion and fluorine compounds have many important uses. Compounds of carbon, hydrogen, and\nfluorine are replacing Freons (compounds of carbon, chlorine, and fluorine) as refrigerants. Teflon is a\npolymer composed of \u2013CF2CF2\u2013 units. Fluoride ion is added to water supplies and to some toothpastes as SnF2\nor NaF to fight tooth decay. Fluoride partially converts teeth from Ca5(PO4)3(OH) into Ca5(PO4)3F.\n"]], ["block_4", ["Chlorine is important to bleach wood pulp and cotton cloth. The chlorine reacts with water to form\nhypochlorous acid, which oxidizes colored substances to colorless ones. Large quantities of chlorine are\nimportant in chlorinating hydrocarbons (replacing hydrogen with chlorine) to produce compounds such as\ntetrachloride (CCl4), chloroform (CHCl3), and ethyl chloride (C2H5Cl), and in the production of polyvinyl\nchloride (PVC) and other polymers. Chlorine is also important to kill the bacteria in community water supplies.\n"]], ["block_5", ["Bromine is important in the production of certain dyes, and sodium and potassium bromides are used as\nsedatives. At one time, light-sensitive silver bromide was a component of photographic film.\n"]], ["block_6", ["Iodine in alcohol solution with potassium iodide is an antiseptic (tincture of iodine). Iodide salts are essential\nfor the proper functioning of the thyroid gland; an iodine deficiency may lead to the development of a goiter.\nIodized table salt contains 0.023% potassium iodide. Silver iodide is useful in the seeding of clouds to induce\nrain; it was important in the production of photographic film and iodoform, CHI3, is an antiseptic.\n"]], ["block_7", [" 18.12 Occurrence, Preparation, and Properties of the Noble Gases \n"]], ["block_8", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_9", ["The elements in group 18 are the noble gases (helium, neon, argon, krypton, xenon, and radon). They earned\nthe name \u201cnoble\u201d because they were assumed to be nonreactive since they have filled valence shells. In 1962,\nDr. Neil Bartlett at the University of British Columbia proved this assumption to be false.\n"]], ["block_10", ["These elements are present in the atmosphere in small amounts. Some natural gas contains 1\u20132% helium by\nmass. Helium is isolated from natural gas by liquefying the condensable components, leaving only helium as a\ngas. The United States possesses most of the world\u2019s commercial supply of this element in its helium-bearing\ngas fields. Argon, neon, krypton, and xenon come from the fractional distillation of liquid air. Radon comes\nfrom other radioactive elements. More recently, it was observed that this radioactive gas is present in very\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["\u2022\nDescribe the properties, preparation, and uses of the noble gases\n"]], ["block_13", [" TABLE 18.3 \n"]], ["block_14", [" YX \n YX 3\n YX 5\n YX 7\n"]], ["block_15", ["ClF(g)\nClF3(g)\nClF5(g)\n"]], ["block_16", ["BrF(g)\nBrF3(l)\nBrF5(l)\n"]], ["block_17", ["BrCl(g)\n"]], ["block_18", ["IF(s)\nIF3(s)\nIF5(l)\nIF7(g)\n"]], ["block_19", ["ICl(l)\nICl3(s)\n"]], ["block_20", ["IBr(s)\n"]], ["block_21", ["Interhalogens\n"]]], "page_934": [["block_0", ["small amounts in soils and minerals. Its accumulation in well-insulated, tightly sealed buildings, however,\nconstitutes a health hazard, primarily lung cancer.\n"]], ["block_1", ["The boiling points and melting points of the noble gases are extremely low relative to those of other substances\nof comparable atomic or molecular masses. This is because only weak London dispersion forces are present,\nand these forces can hold the atoms together only when molecular motion is very slight, as it is at very low\ntemperatures. Helium is the only substance known that does not solidify on cooling at normal pressure. It\nremains liquid close to absolute zero (0.001 K) at ordinary pressures, but it solidifies under elevated pressure.\n"]], ["block_2", ["Helium is used for filling balloons and lighter-than-air craft because it does not burn, making it safer to use\nthan hydrogen. Helium at high pressures is not a narcotic like nitrogen. Thus, mixtures of oxygen and helium\nare important for divers working under high pressures. Using a helium-oxygen mixture avoids the disoriented\nmental state known as nitrogen narcosis, the so-called rapture of the deep. Helium is important as an inert\natmosphere for the melting and welding of easily oxidizable metals and for many chemical processes that are\nsensitive to air.\n"]], ["block_3", ["Liquid helium (boiling point, 4.2 K) is an important coolant to reach the low temperatures necessary for\ncryogenic research, and it is essential for achieving the low temperatures necessary to produce\nsuperconduction in traditional superconducting materials used in powerful magnets and other devices. This\ncooling ability is necessary for the magnets used for magnetic resonance imaging, a common medical\ndiagnostic procedure. The other common coolant is liquid nitrogen (boiling point, 77 K), which is significantly\ncheaper.\n"]], ["block_4", ["Neon is a component of neon lamps and signs. Passing an electric spark through a tube containing neon at low\npressure generates the familiar red glow of neon. It is possible to change the color of the light by mixing argon\nor mercury vapor with the neon or by utilizing glass tubes of a special color.\n"]], ["block_5", ["Argon was useful in the manufacture of gas-filled electric light bulbs, where its lower heat conductivity and\nchemical inertness made it preferable to nitrogen for inhibiting the vaporization of the tungsten filament and\nprolonging the life of the bulb. Fluorescent tubes commonly contain a mixture of argon and mercury vapor.\nArgon is the third most abundant gas in dry air.\n"]], ["block_6", ["Krypton-xenon flash tubes are used to take high-speed photographs. An electric discharge through such a tube\ngives a very intense light that lasts only\nof a second. Krypton forms a difluoride, KrF2, which is\n"]], ["block_7", ["thermally unstable at room temperature.\n"]], ["block_8", ["Stable compounds of xenon form when xenon reacts with fluorine. Xenon difluoride, XeF2, forms after heating\nan excess of xenon gas with fluorine gas and then cooling. The material forms colorless crystals, which are\nstable at room temperature in a dry atmosphere. Xenon tetrafluoride, XeF4, and xenon hexafluoride, XeF6, are\nprepared in an analogous manner, with a stoichiometric amount of fluorine and an excess of fluorine,\nrespectively. Compounds with oxygen are prepared by replacing fluorine atoms in the xenon fluorides with\noxygen.\n"]], ["block_9", ["When XeF6 reacts with water, a solution of XeO3 results and the xenon remains in the 6+-oxidation state:\n"]], ["block_10", ["Dry, solid xenon trioxide, XeO3, is extremely explosive\u2014it will spontaneously detonate. Both XeF6 and XeO3\ndisproportionate in basic solution, producing xenon, oxygen, and salts of the perxenate ion,\nin which\n"]], ["block_11", ["xenon reaches its maximum oxidation sate of 8+.\n"]], ["block_12", ["Radon apparently forms RnF2\u2014evidence of this compound comes from radiochemical tracer techniques.\n"]], ["block_13", ["Unstable compounds of argon form at low temperatures, but stable compounds of helium and neon are not\nknown.\n"]], ["block_14", [" 18.12 \u2022 Occurrence, Preparation, and Properties of the Noble Gases \n 921 \n"]]], "page_935": [["block_0", [" 922 \n 18 \u2022 Key Terms \n"]], ["block_1", [" Key Terms \n"]], ["block_2", [" acid anhydride \ncompound that reacts with water\n"]], ["block_3", [" alkaline earth metal \nany of the metals (beryllium,\n"]], ["block_4", [" allotropes \ntwo or more forms of the same element,\n"]], ["block_5", [" amorphous \nsolid material such as a glass that does\n"]], ["block_6", [" base anhydride \nmetal oxide that behaves as a base\n"]], ["block_7", [" bicarbonate anion \nsalt of the hydrogen carbonate\n"]], ["block_8", [" bismuth \nheaviest member of group 15; a less\n"]], ["block_9", [" borate \ncompound containing boron-oxygen bonds,\n"]], ["block_10", [" carbonate \nsalt of the anion\noften formed\n"]], ["block_11", [" chemical reduction \nmethod of preparing a\n"]], ["block_12", [" chlor-alkali process \nelectrolysis process for the\n"]], ["block_13", [" disproportionation reaction \nchemical reaction\n"]], ["block_14", [" Downs cell \nelectrochemical cell used for the\n"]], ["block_15", [" Frasch process \nimportant in the mining of free\n"]], ["block_16", [" Haber process \nmain industrial process used to\n"]], ["block_17", [" halide \ncompound containing an anion of a group\n"]], ["block_18", [" Hall\u2013H\u00e9roult cell \nelectrolysis apparatus used to\n"]], ["block_19", [" hydrogen carbonate \nsalt of carbonic acid, H2CO3\n"]], ["block_20", [" Access for free at openstax.org \n"]], ["block_21", ["to form an acid or acidic solution\n"]], ["block_22", ["magnesium, calcium, strontium, barium, and\nradium) occupying group 2 of the periodic table;\nthey are reactive, divalent metals that form basic\noxides\n"]], ["block_23", ["in the same physical state, with different\nchemical structures\n"]], ["block_24", ["not have a regular repeating component to its\nthree-dimensional structure; a solid but not a\ncrystal\n"]], ["block_25", ["towards acids\n"]], ["block_26", ["ion,\n"]], ["block_27", ["reactive metal than other representative metals\n"]], ["block_28", ["typically with clusters or chains as a part of the\nchemical structure\n"]], ["block_29", ["by the reaction of carbon dioxide with bases\n"]], ["block_30", ["representative metal using a reducing agent\n"]], ["block_31", ["synthesis of chlorine and sodium hydroxide\n"]], ["block_32", ["where a single reactant is simultaneously\nreduced and oxidized; it is both the reducing\nagent and the oxidizing agent\n"]], ["block_33", ["commercial preparation of metallic sodium (and\nchlorine) from molten sodium chloride\n"]], ["block_34", ["sulfur from enormous underground deposits\n"]], ["block_35", ["produce ammonia from nitrogen and hydrogen;\ninvolves the use of an iron catalyst and elevated\ntemperatures and pressures\n"]], ["block_36", ["17 element in the 1\u2212 oxidation state (fluoride, F;\nchloride, Cl; bromide, Br; and iodide, I)\n"]], ["block_37", ["isolate pure aluminum metal from a solution of\nalumina in molten cryolite\n"]], ["block_38", ["(containing the anion\nin which one\n"]], ["block_39", ["hydrogen atom has been replaced; an acid\ncarbonate; also known as bicarbonate ion\n"]], ["block_40", [" hydrogen halide \nbinary compound formed\n"]], ["block_41", [" hydrogen sulfate \nion\n"]], ["block_42", [" hydrogen sulfite \nion\n"]], ["block_43", [" hydrogenation \naddition of hydrogen (H2) to reduce\n"]], ["block_44", [" hydroxide \ncompound of a metal with the\n"]], ["block_45", [" interhalogen \ncompound formed from two or more\n"]], ["block_46", [" metal (representative) \natoms of the metallic\n"]], ["block_47", [" metalloid \nelement that has properties that are\n"]], ["block_48", [" nitrate \nion; salt of nitric acid\n"]], ["block_49", [" nitrogen fixation \nformation of nitrogen\n"]], ["block_50", [" Ostwald process \nindustrial process used to\n"]], ["block_51", [" oxide \nbinary compound of oxygen with another\n"]], ["block_52", [" ozone \nallotrope of oxygen; O3\n"]], ["block_53", [" passivation \nmetals with a protective nonreactive\n"]], ["block_54", [" peroxide \nmolecule containing two oxygen atoms\n"]], ["block_55", [" photosynthesis \nprocess whereby light energy\n"]], ["block_56", [" Pidgeon process \nchemical reduction process used\n"]], ["block_57", [" polymorph \nvariation in crystalline structure that\n"]], ["block_58", [" representative element \nelement where the s and p\n"]], ["block_59", [" representative metal \nmetal among the\n"]], ["block_60", [" silicate \ncompound containing silicon-oxygen\n"]], ["block_61", ["between hydrogen and the halogens: HF, HCl,\nHBr, and HI\n"]], ["block_62", ["a compound\n"]], ["block_63", ["hydroxide ion OHor the group \u2212OH\n"]], ["block_64", ["different halogens\n"]], ["block_65", ["elements of groups 1, 2, 12, 13, 14, 15, and 16,\nwhich form ionic compounds by losing electrons\nfrom their outer s or p orbitals\n"]], ["block_66", ["between those of metals and nonmetals; these\nelements are typically semiconductors\n"]], ["block_67", ["compounds from molecular nitrogen\n"]], ["block_68", ["convert ammonia into nitric acid\n"]], ["block_69", ["element or group, typically containing Oions or\nthe group \u2013O\u2013 or =O\n"]], ["block_70", ["film of oxide or other compound that creates a\nbarrier for chemical reactions; physical or\nchemical removal of the passivating film allows\nthe metals to demonstrate their expected\nchemical reactivity\n"]], ["block_71", ["bonded together or as the anion,\n"]], ["block_72", ["promotes the reaction of water and carbon\ndioxide to form carbohydrates and oxygen; this\nallows photosynthetic organisms to store energy\n"]], ["block_73", ["to produce magnesium through the thermal\nreaction of magnesium oxide with silicon\n"]], ["block_74", ["results in different physical properties for the\nresulting compound\n"]], ["block_75", ["orbitals are filling\n"]], ["block_76", ["representative elements\n"]], ["block_77", ["bonds, with silicate tetrahedra connected in\nrings, sheets, or three-dimensional networks,\n"]]], "page_936": [["block_0", [" sulfate \nion\n"]], ["block_1", [" Summary \n"]], ["block_2", [" 18.1 Periodicity \n"]], ["block_3", ["This section focuses on the periodicity of the\nrepresentative elements. These are the elements\nwhere the electrons are entering the s and p orbitals.\nThe representative elements occur in groups 1, 2,\nand 12\u201318. These elements are representative\nmetals, metalloids, and nonmetals. The alkali metals\n(group 1) are very reactive, readily form ions with a\ncharge of 1+ to form ionic compounds that are\nusually soluble in water, and react vigorously with\nwater to form hydrogen gas and a basic solution of\nthe metal hydroxide. The outermost electrons of the\nalkaline earth metals (group 2) are more difficult to\nremove than the outer electron of the alkali metals,\nleading to the group 2 metals being less reactive\nthan those in group 1. These elements easily form\ncompounds in which the metals exhibit an oxidation\nstate of 2+. Zinc, cadmium, and mercury (group 12)\ncommonly exhibit the group oxidation state of 2+\n(although mercury also exhibits an oxidation state of\n1+ in compounds that contain\nAluminum,\n"]], ["block_4", ["gallium, indium, and thallium (group 13) are easier\nto oxidize than is hydrogen. Aluminum, gallium, and\nindium occur with an oxidation state 3+ (however,\nthallium also commonly occurs as the Tlion). Tin\nand lead form stable divalent cations and covalent\ncompounds in which the metals exhibit the 4+-\noxidation state.\n"]], ["block_5", [" 18.2 Occurrence and Preparation of the \n Representative Metals \n"]], ["block_6", ["Because of their chemical reactivity, it is necessary\nto produce the representative metals in their pure\nforms by reduction from naturally occurring\ncompounds. Electrolysis is important in the\nproduction of sodium, potassium, and aluminum.\nChemical reduction is the primary method for the\nisolation of magnesium, zinc, and tin. Similar\nprocedures are important for the other\nrepresentative metals.\n"]], ["block_7", [" 18.3 Structure and General Properties of the \n Metalloids \n"]], ["block_8", ["The elements boron, silicon, germanium, arsenic,\nantimony, and tellurium separate the metals from\nthe nonmetals in the periodic table. These elements,\ncalled metalloids or sometimes semimetals, exhibit\n"]], ["block_9", ["depending on the other elements involved in the\nformation of the compounds\n"]], ["block_10", [" sulfite \nion\n"]], ["block_11", [" superoxide \noxide containing the anion\n"]], ["block_12", ["properties characteristic of both metals and\nnonmetals. The structures of these elements are\nsimilar in many ways to those of nonmetals, but the\nelements are electrical semiconductors.\n"]], ["block_13", [" 18.4 Structure and General Properties of the \n Nonmetals \n"]], ["block_14", ["Nonmetals have structures that are very different\nfrom those of the metals, primarily because they\nhave greater electronegativity and electrons that are\nmore tightly bound to individual atoms. Most\nnonmetal oxides are acid anhydrides, meaning that\nthey react with water to form acidic solutions.\nMolecular structures are common for most of the\nnonmetals, and several have multiple allotropes\nwith varying physical properties.\n"]], ["block_15", [" 18.5 Occurrence, Preparation, and \n Compounds of Hydrogen \n"]], ["block_16", ["Hydrogen is the most abundant element in the\nuniverse and its chemistry is truly unique. Although\nit has some chemical reactivity that is similar to that\nof the alkali metals, hydrogen has many of the same\nchemical properties of a nonmetal with a relatively\nlow electronegativity. It forms ionic hydrides with\nactive metals, covalent compounds in which it has\nan oxidation state of 1\u2212 with less electronegative\nelements, and covalent compounds in which it has\nan oxidation state of 1+ with more electronegative\nnonmetals. It reacts explosively with oxygen,\nfluorine, and chlorine, less readily with bromine,\nand much less readily with iodine, sulfur, and\nnitrogen. Hydrogen reduces the oxides of metals\nwith lower reduction potentials than chromium to\nform the metal and water. The hydrogen halides are\nall acidic when dissolved in water.\n"]], ["block_17", [" 18.6 Occurrence, Preparation, and \n Properties of Carbonates \n"]], ["block_18", ["The usual method for the preparation of the\ncarbonates of the alkali and alkaline earth metals is\nby reaction of an oxide or hydroxide with carbon\ndioxide. Other carbonates form by precipitation.\nMetal carbonates or hydrogen carbonates such as\nlimestone (CaCO3), the antacid Tums (CaCO3), and\nbaking soda (NaHCO3) are common examples.\nCarbonates and hydrogen carbonates decompose in\n"]], ["block_19", [" 18 \u2022 Summary \n 923 \n"]]], "page_937": [["block_0", [" 924 \n 18 \u2022 Exercises \n"]], ["block_1", ["the presence of acids and most decompose on\nheating.\n"]], ["block_2", [" 18.7 Occurrence, Preparation, and \n Properties of Nitrogen \n"]], ["block_3", ["Nitrogen exhibits oxidation states ranging from 3\u2212\nto 5+. Because of the stability of the N\u2261N triple\nbond, it requires a great deal of energy to make\ncompounds from molecular nitrogen. Active metals\nsuch as the alkali metals and alkaline earth metals\ncan reduce nitrogen to form metal nitrides. Nitrogen\noxides and nitrogen hydrides are also important\nsubstances.\n"]], ["block_4", [" 18.8 Occurrence, Preparation, and \n Properties of Phosphorus \n"]], ["block_5", ["Phosphorus (group 15) commonly exhibits oxidation\nstates of 3\u2212 with active metals and of 3+ and 5+ with\nmore electronegative nonmetals. The halogens and\noxygen will oxidize phosphorus. The oxides are\nphosphorus(V) oxide, P4O10, and phosphorus(III)\noxide, P4O6. The two common methods for\npreparing orthophosphoric acid, H3PO4, are either\nthe reaction of a phosphate with sulfuric acid or the\nreaction of water with phosphorus(V) oxide.\nOrthophosphoric acid is a triprotic acid that forms\nthree types of salts.\n"]], ["block_6", [" 18.9 Occurrence, Preparation, and \n Compounds of Oxygen \n"]], ["block_7", ["Oxygen is one of the most reactive elements. This\nreactivity, coupled with its abundance, makes the\nchemistry of oxygen very rich and well understood.\n"]], ["block_8", ["Compounds of the representative metals with\noxygen exist in three categories (1) oxides, (2)\nperoxides and superoxides, and (3) hydroxides.\nHeating the corresponding hydroxides, nitrates, or\ncarbonates is the most common method for\nproducing oxides. Heating the metal or metal oxide\nin oxygen may lead to the formation of peroxides\nand superoxides. The soluble oxides dissolve in\nwater to form solutions of hydroxides. Most metals\noxides are base anhydrides and react with acids. The\nhydroxides of the representative metals react with\nacids in acid-base reactions to form salts and water.\n"]], ["block_9", [" Exercises \n"]], ["block_10", [" 18.1 Periodicity \n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", [" 1 . How do alkali metals differ from alkaline earth metals in atomic structure and general properties?\n 2 . Why does the reactivity of the alkali metals decrease from cesium to lithium?\n"]], ["block_13", ["The hydroxides have many commercial uses.\n"]], ["block_14", ["All nonmetals except fluorine form multiple oxides.\nNearly all of the nonmetal oxides are acid\nanhydrides. The acidity of oxyacids requires that the\nhydrogen atoms bond to the oxygen atoms in the\nmolecule rather than to the other nonmetal atom.\nGenerally, the strength of the oxyacid increases with\nthe number of oxygen atoms bonded to the\nnonmetal atom and not to a hydrogen.\n"]], ["block_15", [" 18.10 Occurrence, Preparation, and \n Properties of Sulfur \n"]], ["block_16", ["Sulfur (group 16) reacts with almost all metals and\nreadily forms the sulfide ion, S, in which it has as\noxidation state of 2\u2212. Sulfur reacts with most\nnonmetals.\n"]], ["block_17", [" 18.11 Occurrence, Preparation, and \n Properties of Halogens \n"]], ["block_18", ["The halogens form halides with less electronegative\nelements. Halides of the metals vary from ionic to\ncovalent; halides of nonmetals are covalent.\nInterhalogens form by the combination of two or\nmore different halogens.\n"]], ["block_19", ["All of the representative metals react directly with\nelemental halogens or with solutions of the\nhydrohalic acids (HF, HCl, HBr, and HI) to produce\nrepresentative metal halides. Other laboratory\npreparations involve the addition of aqueous\nhydrohalic acids to compounds that contain such\nbasic anions, such as hydroxides, oxides, or\ncarbonates.\n"]], ["block_20", [" 18.12 Occurrence, Preparation, and \n Properties of the Noble Gases \n"]], ["block_21", ["The most significant property of the noble gases\n(group 18) is their inactivity. They occur in low\nconcentrations in the atmosphere. They find uses as\ninert atmospheres, neon signs, and as coolants. The\nthree heaviest noble gases react with fluorine to\nform fluorides. The xenon fluorides are the best\ncharacterized as the starting materials for a few\nother noble gas compounds.\n"]]], "page_938": [["block_0", [" 3 . Predict the formulas for the nine compounds that may form when each species in column 1 of the table reacts\n"]], ["block_1", [" 10 . The elements sodium, aluminum, and chlorine are in the same period.\n"]], ["block_2", [" 11 . Does metallic tin react with HCl?\n 12 . What is tin pest, also known as tin disease?\n 13 . Compare the nature of the bonds in PbCl2 to that of the bonds in PbCl4.\n 14 . Is the reaction of rubidium with water more or less vigorous than that of sodium? How does the rate of\n"]], ["block_3", [" 18.2 Occurrence and Preparation of the Representative Metals \n"]], ["block_4", [" 15 . Write an equation for the reduction of cesium chloride by elemental calcium at high temperature.\n"]], ["block_5", [" 4 . Predict the best choice in each of the following. You may wish to review the chapter on electronic structure\n"]], ["block_6", [" 5 . Sodium chloride and strontium chloride are both white solids. How could you distinguish one from the\n"]], ["block_7", [" 6 . The reaction of quicklime, CaO, with water produces slaked lime, Ca(OH)2, which is widely used in the\n"]], ["block_8", [" 7 . Write a balanced equation for the reaction of elemental strontium with each of the following:\n"]], ["block_9", [" 8 . How many moles of ionic species are present in 1.0 L of a solution marked 1.0 M mercury(I) nitrate?\n 9 . What is the mass of fish, in kilograms, that one would have to consume to obtain a fatal dose of mercury, if\n"]], ["block_10", ["with each species in column 2.\n"]], ["block_11", ["for relevant examples.\n(a) the most metallic of the elements Al, Be, and Ba\n(b) the most covalent of the compounds NaCl, CaCl2, and BeCl2\n(c) the lowest first ionization energy among the elements Rb, K, and Li\n(d) the smallest among Al, Al, and Al\n"]], ["block_12", ["(e) the largest among Cs, Ba, and Xe\n"]], ["block_13", ["other?\n"]], ["block_14", ["construction industry to make mortar and plaster. The reaction of quicklime and water is highly\nexothermic:\n"]], ["block_15", ["(a) What is the enthalpy of reaction per gram of quicklime that reacts?\n(b) How much heat, in kilojoules, is associated with the production of 1 ton of slaked lime?\n"]], ["block_16", ["(a) oxygen\n(b) hydrogen bromide\n(c) hydrogen\n(d) phosphorus\n(e) water\n"]], ["block_17", ["the fish contains 30 parts per million of mercury by weight? (Assume that all the mercury from the fish\nends up as mercury(II) chloride in the body and that a fatal dose is 0.20 g of HgCl2.) How many pounds of\nfish is this?\n"]], ["block_18", ["(a) Which has the greatest electronegativity?\n(b) Which of the atoms is smallest?\n(c) Write the Lewis structure for the simplest covalent compound that can form between aluminum and\nchlorine.\n(d) Will the oxide of each element be acidic, basic, or amphoteric?\n"]], ["block_19", ["reaction of magnesium compare?\n"]], ["block_20", [" 1 \n 2 \n"]], ["block_21", ["Na\nI\n"]], ["block_22", ["Sr\nSe\n"]], ["block_23", ["Al\nO\n"]], ["block_24", [" 18 \u2022 Exercises \n 925 \n"]]], "page_939": [["block_0", [" 926 \n 18 \u2022 Exercises \n"]], ["block_1", [" 16 . Why is it necessary to keep the chlorine and sodium, resulting from the electrolysis of sodium chloride,\n"]], ["block_2", [" 17 . Give balanced equations for the overall reaction in the electrolysis of molten lithium chloride and for the\n"]], ["block_3", [" 18 . The electrolysis of molten sodium chloride or of aqueous sodium chloride produces chlorine.\n"]], ["block_4", [" 19 . What mass, in grams, of hydrogen gas forms during the complete reaction of 10.01 g of calcium with\n"]], ["block_5", [" 20 . How many grams of oxygen gas are necessary to react completely with 3.01\n10atoms of magnesium to\n"]], ["block_6", [" 21 . Magnesium is an active metal; it burns in the form of powder, ribbons, and filaments to provide flashes of\n"]], ["block_7", [" 22 . Why is it possible for an active metal like aluminum to be useful as a structural metal?\n 23 . Describe the production of metallic aluminum by electrolytic reduction.\n 24 . What is the common ore of tin and how is tin separated from it?\n 25 . A chemist dissolves a 1.497-g sample of a type of metal (an alloy of Sn, Pb, Sb, and Cu) in nitric acid, and\n"]], ["block_8", [" 26 . Consider the production of 100 kg of sodium metal using a current of 50,000 A, assuming a 100% yield.\n"]], ["block_9", [" 27 . What mass of magnesium forms when 100,000 A is passed through a MgCl2 melt for 1.00 h if the yield of\n"]], ["block_10", [" 18.3 Structure and General Properties of the Metalloids \n"]], ["block_11", [" 28 . Give the hybridization of the metalloid and the molecular geometry for each of the following compounds\n"]], ["block_12", [" 29 . Write a Lewis structure for each of the following molecules or ions. You may wish to review the chapter on\n"]], ["block_13", [" 30 . Describe the hybridization of boron and the molecular structure about the boron in each of the following:\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["separate during the production of sodium metal?\n"]], ["block_16", ["reactions occurring at the electrodes. You may wish to review the chapter on electrochemistry for relevant\nexamples.\n"]], ["block_17", ["Calculate the mass of chlorine produced from 3.00 kg sodium chloride in each case. You may wish to\nreview the chapter on electrochemistry for relevant examples.\n"]], ["block_18", ["water?\n"]], ["block_19", ["yield magnesium oxide?\n"]], ["block_20", ["brilliant light. Why is it possible to use magnesium in construction?\n"]], ["block_21", ["metastannic acid, H2SnO3, is precipitated. She heats the precipitate to drive off the water, which leaves\n0.4909 g of tin(IV) oxide. What was the percentage of tin in the original sample?\n"]], ["block_22", ["(a) How long will it take to produce the 100 kg of sodium metal?\n(b) What volume of chlorine at 25 \u00b0C and 1.00 atm forms?\n"]], ["block_23", ["magnesium is 85% of the theoretical yield?\n"]], ["block_24", ["or ions. You may wish to review the chapters on chemical bonding and advanced covalent bonding for\nrelevant examples.\n(a) GeH4\n(b) SbF3\n(c) Te(OH)6\n(d) H2Te\n(e) GeF2\n(f) TeCl4\n(g)\n(h) SbCl5\n(i) TeF6\n"]], ["block_25", ["chemical bonding.\n(a) H3BPH3\n(b)\n(c) BBr3\n(d) B(CH3)3\n(e) B(OH)3\n"]], ["block_26", ["(a) H3BPH3\n(b)\n(c) BBr3\n(d) B(CH3)3\n(e) B(OH)3\n"]]], "page_940": [["block_0", [" 31 . Using only the periodic table, write the complete electron configuration for silicon, including any empty\n"]], ["block_1", [" 32 . Write a Lewis structure for each of the following molecules and ions:\n"]], ["block_2", [" 33 . Describe the hybridization of silicon and the molecular structure of the following molecules and ions:\n"]], ["block_3", [" 34 . Describe the hybridization and the bonding of a silicon atom in elemental silicon.\n 35 . Classify each of the following molecules as polar or nonpolar. You may wish to review the chapter on\n"]], ["block_4", [" 36 . Silicon reacts with sulfur at elevated temperatures. If 0.0923 g of silicon reacts with sulfur to give 0.3030 g\n"]], ["block_5", [" 37 . Name each of the following compounds:\n"]], ["block_6", [" 38 . Write a balanced equation for the reaction of elemental boron with each of the following (most of these\n"]], ["block_7", [" 39 . Why is boron limited to a maximum coordination number of four in its compounds?\n 40 . Write a formula for each of the following compounds:\n"]], ["block_8", [" 41 . From the data given in Appendix G, determine the standard enthalpy change and the standard free energy\n"]], ["block_9", [" 42 . A hydride of silicon prepared by the reaction of Mg2Si with acid exerted a pressure of 306 torr at 26 \u00b0C in a\n"]], ["block_10", ["orbitals in the valence shell. You may wish to review the chapter on electronic structure.\n"]], ["block_11", ["(a) (CH3)3SiH\n(b)\n(c) Si2H6\n(d) Si(OH)4\n(e)\n"]], ["block_12", ["(a) (CH3)3SiH\n(b)\n(c) Si2H6\n(d) Si(OH)4\n(e)\n"]], ["block_13", ["chemical bonding.\n(a) SiH4\n(b) Si2H6\n(c) SiCl3H\n(d) SiF4\n(e) SiCl2F2\n"]], ["block_14", ["of silicon sulfide, determine the empirical formula of silicon sulfide.\n"]], ["block_15", ["(a) TeO2\n(b) Sb2S3\n(c) GeF4\n(d) SiH4\n(e) GeH4\n"]], ["block_16", ["reactions require high temperature):\n(a) F2\n(b) O2\n(c) S\n(d) Se\n(e) Br2\n"]], ["block_17", ["(a) silicon dioxide\n(b) silicon tetraiodide\n(c) silane\n(d) silicon carbide\n(e) magnesium silicide\n"]], ["block_18", ["change for each of the following reactions:\n(a)\n(b)\n(c)\n"]], ["block_19", ["bulb with a volume of 57.0 mL. If the mass of the hydride was 0.0861 g, what is its molecular mass? What\nis the molecular formula for the hydride?\n"]], ["block_20", [" 18 \u2022 Exercises \n 927 \n"]]], "page_941": [["block_0", [" 928 \n 18 \u2022 Exercises \n"]], ["block_1", [" 43 . Suppose you discovered a diamond completely encased in a silicate rock. How would you chemically free\n"]], ["block_2", [" 18.4 Structure and General Properties of the Nonmetals \n"]], ["block_3", [" 44 . Carbon forms a number of allotropes, two of which are graphite and diamond. Silicon has a diamond\n"]], ["block_4", [" 45 . Nitrogen in the atmosphere exists as very stable diatomic molecules. Why does phosphorus form less\n"]], ["block_5", [" 46 . Write balanced chemical equations for the reaction of the following acid anhydrides with water:\n"]], ["block_6", [" 47 . Determine the oxidation number of each element in each of the following compounds:\n"]], ["block_7", [" 48 . Determine the oxidation state of sulfur in each of the following:\n"]], ["block_8", [" 49 . Arrange the following in order of increasing electronegativity: F; Cl; O; and S.\n 50 . Why does white phosphorus consist of tetrahedral P4 molecules while nitrogen consists of diatomic N2\n"]], ["block_9", [" 18.5 Occurrence, Preparation, and Compounds of Hydrogen \n"]], ["block_10", [" 51 . Why does hydrogen not exhibit an oxidation state of 1\u2212 when bonded to nonmetals?\n 52 . The reaction of calcium hydride, CaH2, with water can be characterized as a Lewis acid-base reaction:\n"]], ["block_11", [" 53 . In drawing Lewis structures, we learn that a hydrogen atom forms only one bond in a covalent compound.\n"]], ["block_12", [" 54 . What mass of CaH2 is necessary to react with water to provide enough hydrogen gas to fill a balloon at 20\n"]], ["block_13", [" 55 . What mass of hydrogen gas results from the reaction of 8.5 g of KH with water?\n"]], ["block_14", [" 18.6 Occurrence, Preparation, and Properties of Carbonates \n"]], ["block_15", [" 56 . Carbon forms the\nion, yet silicon does not form an analogous\nion. Why?\n"]], ["block_16", [" 57 . Complete and balance the following chemical equations:\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["the diamond without harming it?\n"]], ["block_19", ["structure. Why is there no allotrope of silicon with a graphite structure?\n"]], ["block_20", ["stable P4 molecules instead of P2 molecules?\n"]], ["block_21", ["(a) SO3\n(b) N2O3\n(c) Cl2O7\n(d) P4O10\n(e) NO2\n"]], ["block_22", ["(a) HCN\n(b) OF2\n(c) AsCl3\n"]], ["block_23", ["(a) SO3\n(b) SO2\n(c)\n"]], ["block_24", ["molecules?\n"]], ["block_25", ["Identify the Lewis acid and the Lewis base among the reactants. The reaction is also an oxidation-\nreduction reaction. Identify the oxidizing agent, the reducing agent, and the changes in oxidation number\nthat occur in the reaction.\n"]], ["block_26", ["Why?\n"]], ["block_27", ["\u00b0C and 0.8 atm pressure with a volume of 4.5 L? The balanced equation is:\n"]], ["block_28", ["(a) hardening of plaster containing slaked lime\n"]], ["block_29", ["(b) removal of sulfur dioxide from the flue gas of power plants\n"]], ["block_30", ["(c) the reaction of baking powder that produces carbon dioxide gas and causes bread to rise\n"]]], "page_942": [["block_0", [" 58 . Heating a sample of Na2CO3\u22c5xH2O weighing 4.640 g until the removal of the water of hydration leaves\n"]], ["block_1", [" 18.7 Occurrence, Preparation, and Properties of Nitrogen \n"]], ["block_2", [" 59 . Write the Lewis structures for each of the following:\n"]], ["block_3", [" 60 . For each of the following, indicate the hybridization of the nitrogen atom (for\nthe central nitrogen).\n"]], ["block_4", [" 61 . Explain how ammonia can function both as a Br\u00f8nsted base and as a Lewis base.\n 62 . Determine the oxidation state of nitrogen in each of the following. You may wish to review the chapter on\n"]], ["block_5", [" 63 . For each of the following, draw the Lewis structure, predict the ONO bond angle, and give the\n"]], ["block_6", [" 64 . How many grams of gaseous ammonia will the reaction of 3.0 g hydrogen gas and 3.0 g of nitrogen gas\n"]], ["block_7", [" 65 . Although PF5 and AsF5 are stable, nitrogen does not form NF5 molecules. Explain this difference among\n"]], ["block_8", [" 66 . The equivalence point for the titration of a 25.00-mL sample of CsOH solution with 0.1062 M HNO3 is at\n"]], ["block_9", [" 18.8 Occurrence, Preparation, and Properties of Phosphorus \n"]], ["block_10", [" 67 . Write the Lewis structure for each of the following. You may wish to review the chapter on chemical\n"]], ["block_11", ["1.720 g of anhydrous Na2CO3. What is the formula of the hydrated compound?\n"]], ["block_12", ["(a) NH\n"]], ["block_13", ["(b) N2F4\n(c)\n(d) NF3\n(e)\n"]], ["block_14", ["(a) N2F4\n(b)\n(c) NF3\n(d)\n"]], ["block_15", ["chemical bonding for relevant examples.\n(a) NCl3\n(b) ClNO\n(c) N2O5\n(d) N2O3\n(e)\n(f) N2O4\n(g) N2O\n(h)\n(i) HNO2\n(j) HNO3\n"]], ["block_16", ["hybridization of the nitrogen. You may wish to review the chapters on chemical bonding and advanced\ntheories of covalent bonding for relevant examples.\n(a) NO2\n(b)\n(c)\n"]], ["block_17", ["produce?\n"]], ["block_18", ["members of the same group.\n"]], ["block_19", ["35.27 mL. What is the concentration of the CsOH solution?\n"]], ["block_20", ["bonding and molecular geometry.\n(a) PH3\n(b)\n(c) P2H4\n(d)\n(e) PF5\n"]], ["block_21", [" 18 \u2022 Exercises \n 929 \n"]]], "page_943": [["block_0", [" 930 \n 18 \u2022 Exercises \n"]], ["block_1", [" 68 . Describe the molecular structure of each of the following molecules or ions listed. You may wish to review\n"]], ["block_2", [" 69 . Complete and balance each of the following chemical equations. (In some cases, there may be more than\n"]], ["block_3", [" 70 . Describe the hybridization of phosphorus in each of the following compounds: P4O10, P4O6, PH4I (an ionic\n"]], ["block_4", [" 71 . What volume of 0.200 M NaOH is necessary to neutralize the solution produced by dissolving 2.00 g of\n"]], ["block_5", [" 72 . How much POCl3 can form from 25.0 g of PCl5 and the appropriate amount of H2O?\n 73 . How many tons of Ca3(PO4)2 are necessary to prepare 5.0 tons of phosphorus if the yield is 90%?\n 74 . Write equations showing the stepwise ionization of phosphorous acid.\n 75 . Draw the Lewis structures and describe the geometry for the following:\n"]], ["block_6", [" 76 . Why does phosphorous acid form only two series of salts, even though the molecule contains three\n"]], ["block_7", [" 77 . Assign an oxidation state to phosphorus in each of the following:\n"]], ["block_8", [" 78 . Phosphoric acid, one of the acids used in some cola drinks, is produced by the reaction of phosphorus(V)\n"]], ["block_9", [" 18.9 Occurrence, Preparation, and Compounds of Oxygen \n"]], ["block_10", [" 79 . Predict the product of burning francium in air.\n 80 . Using equations, describe the reaction of water with potassium and with potassium oxide.\n 81 . Write balanced chemical equations for the following reactions:\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["the chapter on chemical bonding and molecular geometry.\n(a) PH3\n(b)\n(c) P2H4\n(d)\n"]], ["block_13", ["one correct answer.)\n(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n"]], ["block_14", ["compound), PBr3, H3PO4, H3PO3, PH3, and P2H4. You may wish to review the chapter on advanced theories\nof covalent bonding.\n"]], ["block_15", ["PCl3 is an excess of water? Note that when H3PO3 is titrated under these conditions, only one proton of the\nacid molecule reacts.\n"]], ["block_16", ["(a)\n(b) PF5\n(c)\n(d) POF3\n"]], ["block_17", ["hydrogen atoms?\n"]], ["block_18", ["(a) NaH2PO3\n(b) PF5\n(c) P4O6\n(d) K3PO4\n(e) Na3P\n(f) Na4P2O7\n"]], ["block_19", ["oxide, an acidic oxide, with water. Phosphorus(V) oxide is prepared by the combustion of phosphorus.\n(a) Write the empirical formula of phosphorus(V) oxide.\n(b) What is the molecular formula of phosphorus(V) oxide if the molar mass is about 280.\n(c) Write balanced equations for the production of phosphorus(V) oxide and phosphoric acid.\n(d) Determine the mass of phosphorus required to make 1.00\n10kg of phosphoric acid, assuming a\n"]], ["block_20", ["yield of 98.85%.\n"]], ["block_21", ["(a) zinc metal heated in a stream of oxygen gas\n(b) zinc carbonate heated until loss of mass stops\n(c) zinc carbonate added to a solution of acetic acid, CH3CO2H\n(d) zinc added to a solution of hydrobromic acid\n"]]], "page_944": [["block_0", [" 82 . Write balanced chemical equations for the following reactions:\n"]], ["block_1", [" 83 . Illustrate the amphoteric nature of aluminum hydroxide by citing suitable equations.\n 84 . Write balanced chemical equations for the following reactions:\n"]], ["block_2", [" 85 . Write balanced chemical equations for the following reactions:\n"]], ["block_3", [" 86 . What volume of 0.250 M H2SO4 solution is required to neutralize a solution that contains 5.00 g of CaCO3?\n 87 . Which is the stronger acid, HClO4 or HBrO4? Why?\n 88 . Write a balanced chemical equation for the reaction of an excess of oxygen with each of the following.\n"]], ["block_4", [" 89 . Which is the stronger acid, H2SO4 or H2SeO4? Why? You may wish to review the chapter on acid-base\n"]], ["block_5", [" 18.10 Occurrence, Preparation, and Properties of Sulfur \n"]], ["block_6", [" 90 . Explain why hydrogen sulfide is a gas at room temperature, whereas water, which has a lower molecular\n"]], ["block_7", [" 91 . Give the hybridization and oxidation state for sulfur in SO2, in SO3, and in H2SO4.\n 92 . Which is the stronger acid, NaHSO3 or NaHSO4?\n 93 . Determine the oxidation state of sulfur in SF6, SO2F2, and KHS.\n 94 . Which is a stronger acid, sulfurous acid or sulfuric acid? Why?\n 95 . Oxygen forms double bonds in O2, but sulfur forms single bonds in S8. Why?\n 96 . Give the Lewis structure of each of the following:\n"]], ["block_8", [" 97 . Write two balanced chemical equations in which sulfuric acid acts as an oxidizing agent.\n 98 . Explain why sulfuric acid, H2SO4, which is a covalent molecule, dissolves in water and produces a solution\n"]], ["block_9", [" 99 . How many grams of Epsom salts (MgSO4\u22c57H2O) will form from 5.0 kg of magnesium?\n"]], ["block_10", [" 18.11 Occurrence, Preparation, and Properties of Halogens \n"]], ["block_11", [" 100 . What does it mean to say that mercury(II) halides are weak electrolytes?\n 101 . Why is SnCl4 not classified as a salt?\n"]], ["block_12", ["(a) cadmium burned in air\n(b) elemental cadmium added to a solution of hydrochloric acid\n(c) cadmium hydroxide added to a solution of acetic acid, CH3CO2H\n"]], ["block_13", ["(a) metallic aluminum burned in air\n(b) elemental aluminum heated in an atmosphere of chlorine\n(c) aluminum heated in hydrogen bromide gas\n(d) aluminum hydroxide added to a solution of nitric acid\n"]], ["block_14", ["(a) sodium oxide added to water\n(b) cesium carbonate added to an excess of an aqueous solution of HF\n(c) aluminum oxide added to an aqueous solution of HClO4\n(d) a solution of sodium carbonate added to solution of barium nitrate\n(e) titanium metal produced from the reaction of titanium tetrachloride with elemental sodium\n"]], ["block_15", ["Remember that oxygen is a strong oxidizing agent and tends to oxidize an element to its maximum\noxidation state.\n(a) Mg\n(b) Rb\n(c) Ga\n(d) C2H2\n(e) CO\n"]], ["block_16", ["equilibria.\n"]], ["block_17", ["mass, is a liquid.\n"]], ["block_18", ["(a) SF4\n(b) K2SO4\n(c) SO2Cl2\n(d) H2SO3\n(e) SO3\n"]], ["block_19", ["that contains ions.\n"]], ["block_20", [" 18 \u2022 Exercises \n 931 \n"]]], "page_945": [["block_0", [" 932 \n 18 \u2022 Exercises \n"]], ["block_1", [" 102 . The following reactions are all similar to those of the industrial chemicals. Complete and balance the\n"]], ["block_2", [" 103 . Which is the stronger acid, HClO3 or HBrO3? Why?\n 104 . What is the hybridization of iodine in IF3 and IF5?\n 105 . Predict the molecular geometries and draw Lewis structures for each of the following. You may wish to\n"]], ["block_3", [" 106 . Which halogen has the highest ionization energy? Is this what you would predict based on what you have\n"]], ["block_4", [" 107 . Name each of the following compounds:\n"]], ["block_5", [" 108 . Explain why, at room temperature, fluorine and chlorine are gases, bromine is a liquid, and iodine is a\n"]], ["block_6", [" 109 . What is the oxidation state of the halogen in each of the following?\n"]], ["block_7", [" 110 . Physiological saline concentration\u2014that is, the sodium chloride concentration in our bodies\u2014is\n"]], ["block_8", [" 18.12 Occurrence, Preparation, and Properties of the Noble Gases \n"]], ["block_9", [" 111 . Give the hybridization of xenon in each of the following. You may wish to review the chapter on the\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", ["equations for these reactions:\n(a) reaction of a weak base and a strong acid\n"]], ["block_12", ["(b) preparation of a soluble silver salt for silver plating\n"]], ["block_13", ["(c) preparation of strontium hydroxide by electrolysis of a solution of strontium chloride\n"]], ["block_14", ["review the chapter on chemical bonding and molecular geometry.\n(a) IF5\n(b)\n(c) PCl5\n(d) SeF4\n(e) ClF3\n"]], ["block_15", ["learned about periodic properties?\n"]], ["block_16", ["(a) BrF3\n(b) NaBrO3\n(c) PBr5\n(d) NaClO4\n(e) KClO\n"]], ["block_17", ["solid.\n"]], ["block_18", ["(a) H5IO6\n(b)\n(c) ClO2\n(d) ICl3\n(e) F2\n"]], ["block_19", ["approximately 0.16 M. A saline solution for contact lenses is prepared to match the physiological\nconcentration. If you purchase 25 mL of contact lens saline solution, how many grams of sodium\nchloride have you bought?\n"]], ["block_20", ["advanced theories of covalent bonding.\n(a) XeF2\n(b) XeF4\n(c) XeO3\n(d) XeO4\n(e) XeOF4\n"]]], "page_946": [["block_0", [" 112 . What is the molecular structure of each of the following molecules? You may wish to review the chapter\n"]], ["block_1", [" 113 . Indicate whether each of the following molecules is polar or nonpolar. You may wish to review the\n"]], ["block_2", [" 114 . What is the oxidation state of the noble gas in each of the following? You may wish to review the chapter\n"]], ["block_3", [" 115 . A mixture of xenon and fluorine was heated. A sample of the white solid that formed reacted with\n"]], ["block_4", [" 116 . Basic solutions of Na4XeO6 are powerful oxidants. What mass of Mn(NO3)2\u20226H2O reacts with 125.0 mL of\n"]], ["block_5", ["on chemical bonding and molecular geometry.\n(a) XeF2\n(b) XeF4\n(c) XeO3\n(d) XeO4\n(e) XeOF4\n"]], ["block_6", ["chapter on chemical bonding and molecular geometry.\n(a) XeF2\n(b) XeF4\n(c) XeO3\n(d) XeO4\n(e) XeOF4\n"]], ["block_7", ["on chemical bonding and molecular geometry.\n(a) XeO2F2\n(b) KrF2\n(c)\n(d)\n(e) XeO3\n"]], ["block_8", ["hydrogen to yield 81 mL of xenon (at STP) and hydrogen fluoride, which was collected in water, giving a\nsolution of hydrofluoric acid. The hydrofluoric acid solution was titrated, and 68.43 mL of 0.3172 M\nsodium hydroxide was required to reach the equivalence point. Determine the empirical formula for the\nwhite solid and write balanced chemical equations for the reactions involving xenon.\n"]], ["block_9", ["a 0.1717 M basic solution of Na4XeO6 that contains an excess of sodium hydroxide if the products\ninclude Xe and solution of sodium permanganate?\n"]], ["block_10", [" 18 \u2022 Exercises \n 933 \n"]]], "page_947": [["block_0", [" 934 \n 18 \u2022 Exercises \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_948": [["block_0", ["CHAPTER 19\nTransition Metals and Coordination\nChemistry\n"]], ["block_1", [{"image_0": "948_0.png", "coords": [72, 131, 622, 279]}]], ["block_2", [" Figure 19.1 \nTransition metals often form vibrantly colored complexes. The minerals malachite (green), azurite\n"]], ["block_3", ["(blue), and proustite (red) are some examples. (credit left: modification of work by James St. John; credit middle:\nmodification of work by Stephanie Clifford; credit right: modification of work by Terry Wallace)\n"]], ["block_4", [" CHAPTER OUTLINE \n"]], ["block_5", [" 19.1 Occurrence, Preparation, and Properties of Transition Metals and Their Compounds \n 19.2 Coordination Chemistry of Transition Metals \n 19.3 Spectroscopic and Magnetic Properties of Coordination Compounds \n"]], ["block_6", [" INTRODUCTION \n"]], ["block_7", ["in your spiral notebook and the cutlery in your kitchen to automobiles, ships, buildings, and in the hemoglobin\nin your blood. Titanium is useful in the manufacture of lightweight, durable products such as bicycle frames,\nartificial hips, and jewelry. Chromium is useful as a protective plating on plumbing fixtures and automotive\ndetailing.\n"]], ["block_8", ["In addition to being used in their pure elemental forms, many compounds containing transition metals have\nnumerous other applications. Silver nitrate is used to create mirrors, zirconium silicate provides friction in\nautomotive brakes, and many important cancer-fighting agents, like the drug cisplatin and related species, are\nplatinum compounds.\n"]], ["block_9", ["The variety of properties exhibited by transition metals is due to their complex valence shells. Unlike most\nmain group metals where one oxidation state is normally observed, the valence shell structure of transition\nmetals means that they usually occur in several different stable oxidation states. In addition, electron\ntransitions in these elements can correspond with absorption of photons in the visible electromagnetic\nspectrum, leading to colored compounds. Because of these behaviors, transition metals exhibit a rich and\nfascinating chemistry.\n"]], ["block_10", [" 19.1 Occurrence, Preparation, and Properties of Transition Metals and Their \n Compounds \n"]], ["block_11", ["Transition metals are defined as those elements that have (or readily form) partially filled d orbitals. As shown\nin Figure 19.2, the d-block elements in groups 3\u201311 are transition elements. The f-block elements , also\ncalled inner transition metals (the lanthanides and actinides), also meet this criterion because the d orbital is\npartially occupied before the f orbitals. The d orbitals fill with the copper family (group 11); for this reason, the\n"]], ["block_12", ["We have daily contact with many transition metals. Iron occurs everywhere\u2014from the rings\n"]]], "page_949": [["block_0", [" 936 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", ["next family (group 12) are technically not transition elements. However, the group 12 elements do display\nsome of the same chemical properties and are commonly included in discussions of transition metals. Some\nchemists do treat the group 12 elements as transition metals.\n"]], ["block_2", [{"image_0": "949_0.png", "coords": [72, 101, 540, 467]}]], ["block_3", [" FIGURE 19.2 \nThe transition metals are located in groups 3\u201311 of the periodic table. The inner transition metals\n"]], ["block_4", ["are in the two rows below the body of the table.\n"]], ["block_5", ["The d-block elements are divided into the first transition series (the elements Sc through Cu), the second \n transition series (the elements Y through Ag), and the third transition series (the element La and the\nelements Hf through Au). Actinium, Ac, is the first member of the fourth transition series , which also includes\nRf through Rg.\n"]], ["block_6", ["The f-block elements are the elements Ce through Lu, which constitute the lanthanide series (or lanthanoid \n series ), and the elements Th through Lr, which constitute the actinide series (or actinoid series ). Because\nlanthanum behaves very much like the lanthanide elements, it is considered a lanthanide element, even\nthough its electron configuration makes it the first member of the third transition series. Similarly, the\nbehavior of actinium means it is part of the actinide series, although its electron configuration makes it the\nfirst member of the fourth transition series.\n"]], ["block_7", [" Valence Electrons in Transition Metals \n"]], ["block_8", ["Review how to write electron configurations, covered in the chapter on electronic structure and periodic\nproperties of elements. Recall that for the transition and inner transition metals, it is necessary to remove the s\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["EXAMPLE 19.1\n"]]], "page_950": [["block_0", ["electrons before the d or f electrons. Then, for each ion, give the electron configuration:\n"]], ["block_1", ["(a) cerium(III)\n"]], ["block_2", ["(b) lead(II)\n"]], ["block_3", ["(c) Ti\n"]], ["block_4", ["(d) Am\n"]], ["block_5", ["(e) Pd\n"]], ["block_6", ["For the examples that are transition metals, determine to which series they belong.\n"]], ["block_7", [" Solution \n"]], ["block_8", ["For ions, the s-valence electrons are lost prior to the d or f electrons.\n"]], ["block_9", ["(a) Ce[Xe]4f; Ceis an inner transition element in the lanthanide series.\n"]], ["block_10", ["(b) Pb[Xe]6s5d4f; the electrons are lost from the p orbital. This is a main group element.\n(c) titanium(II) [Ar]3d; first transition series\n"]], ["block_11", ["(d) americium(III) [Rn]5f; actinide\n"]], ["block_12", ["(e) palladium(II) [Kr]4d; second transition series\n"]], ["block_13", [" Check Your Learning \n"]], ["block_14", ["Give an example of an ion from the first transition series with no d electrons.\n"]], ["block_15", [" Answer: \nVis one possibility. Other examples include Sc, Ti, Cr, and Mn.\n"]], ["block_16", ["Chemistry in Everyday Life\n"]], ["block_17", [" Uses of Lanthanides in Devices \nLanthanides (elements 57\u201371) are fairly abundant in the earth\u2019s crust, despite their historic\ncharacterization as rare earth elements . Thulium, the rarest naturally occurring lanthanoid, is more\ncommon in the earth\u2019s crust than silver (4.5\n10% versus 0.79\n10% by mass). There are 17 rare\n"]], ["block_18", ["earth elements, consisting of the 15 lanthanoids plus scandium and yttrium. They are called rare because\nthey were once difficult to extract economically, so it was rare to have a pure sample; due to similar\nchemical properties, it is difficult to separate any one lanthanide from the others. However, newer\nseparation methods, such as ion exchange resins similar to those found in home water softeners, make the\nseparation of these elements easier and more economical. Most ores that contain these elements have low\nconcentrations of all the rare earth elements mixed together.\n"]], ["block_19", ["The commercial applications of lanthanides are growing rapidly. For example, europium is important in\nflat screen displays found in computer monitors, cell phones, and televisions. Neodymium is useful in\nlaptop hard drives and in the processes that convert crude oil into gasoline (Figure 19.3). Holmium is found\nin dental and medical equipment. In addition, many alternative energy technologies rely heavily on\nlanthanoids. Neodymium and dysprosium are key components of hybrid vehicle engines and the magnets\nused in wind turbines.\n"]], ["block_20", [" 19.1 \u2022 Occurrence, Preparation, and Properties of Transition Metals and Their Compounds \n 937 \n"]]], "page_951": [["block_0", [" 938 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", ["Both the d- and f-block elements react with nonmetals to form binary compounds; heating is often required.\nThese elements react with halogens to form a variety of halides ranging in oxidation state from 1+ to 6+. On\nheating, oxygen reacts with all of the transition elements except palladium, platinum, silver, and gold. The\noxides of these latter metals can be formed using other reactants, but they decompose upon heating. The\nf-block elements, the elements of group 3, and the elements of the first transition series except copper react\nwith aqueous solutions of acids, forming hydrogen gas and solutions of the corresponding salts.\n"]], ["block_2", ["The transition elements have many properties in common with other metals. They are almost all hard, high-\nmelting solids that conduct heat and electricity well. They readily form alloys and lose electrons to form stable\ncations. In addition, transition metals form a wide variety of stable coordination compounds , in which the\ncentral metal atom or ion acts as a Lewis acid and accepts one or more pairs of electrons. Many different\nmolecules and ions can donate lone pairs to the metal center, serving as Lewis bases. In this chapter, we shall\nfocus primarily on the chemical behavior of the elements of the first transition series.\n"]], ["block_3", [" Properties of the Transition Elements \n"]], ["block_4", ["Transition metals demonstrate a wide range of chemical behaviors. As can be seen from their reduction\npotentials (see Appendix H), some transition metals are strong reducing agents, whereas others have very low\nreactivity. For example, the lanthanides all form stable 3+ aqueous cations. The driving force for such\noxidations is similar to that of alkaline earth metals such as Be or Mg, forming Beand Mg. On the other\nhand, materials like platinum and gold have much higher reduction potentials. Their ability to resist oxidation\nmakes them useful materials for constructing circuits and jewelry.\n"]], ["block_5", ["Ions of the lighter d-block elements, such as Cr, Fe, and Co, form colorful hydrated ions that are stable in\nwater. However, ions in the period just below these (Mo, Ru, and Ir) are unstable and react readily with\noxygen from the air. The majority of simple, water-stable ions formed by the heavier d-block elements are\noxyanions such as\nand\n"]], ["block_6", ["Ruthenium, osmium, rhodium, iridium, palladium, and platinum are the platinum metals . With difficulty,\nthey form simple cations that are stable in water, and, unlike the earlier elements in the second and third\ntransition series, they do not form stable oxyanions.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [" FIGURE 19.3 \n(a) Europium is used in display screens for televisions, computer monitors, and cell phones. (b)\n"]], ["block_9", ["Neodymium magnets are commonly found in computer hard drives. (credit b: modification of work by \u201cKUERT\nDatenrettung\u201d/Flickr)\n"]], ["block_10", ["As the demand for lanthanide materials has increased faster than supply, prices have also increased. In\n2008, dysprosium cost $110/kg; by 2014, the price had increased to $470/kg. Increasing the supply of\nlanthanoid elements is one of the most significant challenges facing the industries that rely on the optical\nand magnetic properties of these materials.\n"]], ["block_11", [{"image_0": "951_0.png", "coords": [90, 57, 522, 248]}]]], "page_952": [["block_0", ["Transition metals can form compounds with a wide range of oxidation states. Some of the observed oxidation\nstates of the elements of the first transition series are shown in Figure 19.4. As we move from left to right\nacross the first transition series, we see that the number of common oxidation states increases at first to a\nmaximum towards the middle of the table, then decreases. The values in the table are typical values; there are\nother known values, and it is possible to synthesize new additions. For example, in 2014, researchers were\nsuccessful in synthesizing a new oxidation state of iridium (9+).\n"]], ["block_1", ["For the elements scandium through manganese (the first half of the first transition series), the highest\noxidation state corresponds to the loss of all of the electrons in both the s and d orbitals of their valence shells.\nThe titanium(IV) ion, for example, is formed when the titanium atom loses its two 3d and two 4s electrons.\nThese highest oxidation states are the most stable forms of scandium, titanium, and vanadium. However, it is\nnot possible to continue to remove all of the valence electrons from metals as we continue through the series.\nIron is known to form oxidation states from 2+ to 6+, with iron(II) and iron(III) being the most common. Most of\nthe elements of the first transition series form ions with a charge of 2+ or 3+ that are stable in water, although\nthose of the early members of the series can be readily oxidized by air.\n"]], ["block_2", ["The elements of the second and third transition series generally are more stable in higher oxidation states\nthan are the elements of the first series. In general, the atomic radius increases down a group, which leads to\nthe ions of the second and third series being larger than are those in the first series. Removing electrons from\norbitals that are located farther from the nucleus is easier than removing electrons close to the nucleus. For\nexample, molybdenum and tungsten, members of group 6, are limited mostly to an oxidation state of 6+ in\naqueous solution. Chromium, the lightest member of the group, forms stable Crions in water and, in the\nabsence of air, less stable Crions. The sulfide with the highest oxidation state for chromium is Cr2S3, which\ncontains the Crion. Molybdenum and tungsten form sulfides in which the metals exhibit oxidation states of\n4+ and 6+.\n"]], ["block_3", [" Activity of the Transition Metals \n"]], ["block_4", ["Which is the strongest oxidizing agent in acidic solution: dichromate ion, which contains chromium(VI),\npermanganate ion, which contains manganese(VII), or titanium dioxide, which contains titanium(IV)?\n"]], ["block_5", [" Solution \n"]], ["block_6", ["First, we need to look up the reduction half reactions (in Appendix L) for each oxide in the specified oxidation\nstate:\n"]], ["block_7", ["A larger reduction potential means that it is easier to reduce the reactant. Permanganate, with the largest\nreduction potential, is the strongest oxidizer under these conditions. Dichromate is next, followed by titanium\ndioxide as the weakest oxidizing agent (the hardest to reduce) of this set.\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["Predict what reaction (if any) will occur between HCl and Co(s), and between HBr and Pt(s). You will need to use\n"]], ["block_10", [" FIGURE 19.4 \nTransition metals of the first transition series can form compounds with varying oxidation states.\n"]], ["block_11", ["EXAMPLE 19.2\n"]], ["block_12", [{"image_0": "952_0.png", "coords": [130, 139, 481, 213]}]], ["block_13", [" 19.1 \u2022 Occurrence, Preparation, and Properties of Transition Metals and Their Compounds \n 939 \n"]]], "page_953": [["block_0", [" 940 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", ["In general, it is not difficult to reduce ions of the d-block elements to the free element. Carbon is a sufficiently\nstrong reducing agent in most cases. However, like the ions of the more active main group metals, ions of the\nf-block elements must be isolated by electrolysis or by reduction with an active metal such as calcium.\n"]], ["block_2", ["the standard reduction potentials from Appendix L.\n"]], ["block_3", [" Answer: \n"]], ["block_4", [" Preparation of the Transition Elements \n"]], ["block_5", ["Ancient civilizations knew about iron, copper, silver, and gold. The time periods in human history known as\nthe Bronze Age and Iron Age mark the advancements in which societies learned to isolate certain metals and\nuse them to make tools and goods. Naturally occurring ores of copper, silver, and gold can contain high\nconcentrations of these metals in elemental form (Figure 19.5). Iron, on the other hand, occurs on earth almost\nexclusively in oxidized forms, such as rust (Fe2O3). The earliest known iron implements were made from iron\nmeteorites. Surviving iron artifacts dating from approximately 4000 to 2500 BC are rare, but all known\nexamples contain specific alloys of iron and nickel that occur only in extraterrestrial objects, not on earth. It\ntook thousands of years of technological advances before civilizations developed iron smelting , the ability to\nextract a pure element from its naturally occurring ores and for iron tools to become common.\n"]], ["block_6", [{"image_0": "953_0.png", "coords": [72, 264, 540, 414]}]], ["block_7", [" FIGURE 19.5 \nTransition metals occur in nature in various forms. Examples include (a) a nugget of copper, (b) a\n"]], ["block_8", ["deposit of gold, and (c) an ore containing oxidized iron. (credit a: modification of work by http://images-of-\nelements.com/copper-2.jpg; credit c: modification of work by http://images-of-elements.com/iron-ore.jpg)\n"]], ["block_9", ["Generally, the transition elements are extracted from minerals found in a variety of ores. However, the ease of\ntheir recovery varies widely, depending on the concentration of the element in the ore, the identity of the other\nelements present, and the difficulty of reducing the element to the free metal.\n"]], ["block_10", ["We shall discuss the processes used for the isolation of iron, copper, and silver because these three processes\nillustrate the principal means of isolating most of the d-block metals. In general, each of these processes\ninvolves three principal steps: preliminary treatment, smelting, and refining.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["1.\nPreliminary treatment. In general, there is an initial treatment of the ores to make them suitable for the\nextraction of the metals. This usually involves crushing or grinding the ore, concentrating the metal-\nbearing components, and sometimes treating these substances chemically to convert them into\ncompounds that are easier to reduce to the metal.\n"]], ["block_13", ["2.\nSmelting. The next step is the extraction of the metal in the molten state, a process called smelting, which\nincludes reduction of the metallic compound to the metal. Impurities may be removed by the addition of a\ncompound that forms a slag\u2014a substance with a low melting point that can be readily separated from the\nmolten metal.\n"]], ["block_14", ["3.\nRefining. The final step in the recovery of a metal is refining the metal. Low boiling metals such as zinc and\nmercury can be refined by distillation. When fused on an inclined table, low melting metals like tin flow\naway from higher-melting impurities. Electrolysis is another common method for refining metals.\n"]], ["block_15", ["no reaction because Pt(s) will not be oxidized by H\n"]]], "page_954": [["block_0", [" Isolation of Iron \n"]], ["block_1", ["The early application of iron to the manufacture of tools and weapons was possible because of the wide\ndistribution of iron ores and the ease with which iron compounds in the ores could be reduced by carbon. For a\nlong time, charcoal was the form of carbon used in the reduction process. The production and use of iron\nbecame much more widespread about 1620, when coke was introduced as the reducing agent. Coke is a form\nof carbon formed by heating coal in the absence of air to remove impurities.\n"]], ["block_2", ["The first step in the metallurgy of iron is usually roasting the ore (heating the ore in air) to remove water,\ndecomposing carbonates into oxides, and converting sulfides into oxides. The oxides are then reduced in a\nblast furnace that is 80\u2013100 feet high and about 25 feet in diameter (Figure 19.6) in which the roasted ore,\ncoke, and limestone (impure CaCO3) are introduced continuously into the top. Molten iron and slag are\nwithdrawn at the bottom. The entire stock in a furnace may weigh several hundred tons.\n"]], ["block_3", [{"image_0": "954_0.png", "coords": [72, 216, 540, 557]}]], ["block_4", [" FIGURE 19.6 \nWithin a blast furnace, different reactions occur in different temperature zones. Carbon monoxide is\n"]], ["block_5", ["generated in the hotter bottom regions and rises upward to reduce the iron oxides to pure iron through a series of\nreactions that take place in the upper regions.\n"]], ["block_6", ["Near the bottom of a furnace are nozzles through which preheated air is blown into the furnace. As soon as the\nair enters, the coke in the region of the nozzles is oxidized to carbon dioxide with the liberation of a great deal\nof heat. The hot carbon dioxide passes upward through the overlying layer of white-hot coke, where it is\nreduced to carbon monoxide:\n"]], ["block_7", ["The carbon monoxide serves as the reducing agent in the upper regions of the furnace. The individual\nreactions are indicated in Figure 19.6.\n"]], ["block_8", ["The iron oxides are reduced in the upper region of the furnace. In the middle region, limestone (calcium\ncarbonate) decomposes, and the resulting calcium oxide combines with silica and silicates in the ore to form\n"]], ["block_9", [" 19.1 \u2022 Occurrence, Preparation, and Properties of Transition Metals and Their Compounds \n 941 \n"]]], "page_955": [["block_0", [" 942 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", ["slag. The slag is mostly calcium silicate and contains most of the commercially unimportant components of\nthe ore:\n"]], ["block_2", ["Just below the middle of the furnace, the temperature is high enough to melt both the iron and the slag. They\ncollect in layers at the bottom of the furnace; the less dense slag floats on the iron and protects it from\noxidation. Several times a day, the slag and molten iron are withdrawn from the furnace. The iron is\ntransferred to casting machines or to a steelmaking plant (Figure 19.7).\n"]], ["block_3", ["Much of the iron produced is refined and converted into steel. Steel is made from iron by removing impurities\nand adding substances such as manganese, chromium, nickel, tungsten, molybdenum, and vanadium to\nproduce alloys with properties that make the material suitable for specific uses. Most steels also contain small\nbut definite percentages of carbon (0.04%\u20132.5%). However, a large part of the carbon contained in iron must\nbe removed in the manufacture of steel; otherwise, the excess carbon would make the iron brittle.\n"]], ["block_4", ["You can watch an animation of steelmaking (http://openstax.org/l/16steelmaking) that walks you through the\nprocess.\n"]], ["block_5", [" Isolation of Copper \n"]], ["block_6", ["The most important ores of copper contain copper sulfides (such as covellite, CuS), although copper oxides\n(such as tenorite, CuO) and copper hydroxycarbonates [such as malachite, Cu2(OH)2CO3] are sometimes found.\nIn the production of copper metal, the concentrated sulfide ore is roasted to remove part of the sulfur as sulfur\ndioxide. The remaining mixture, which consists of Cu2S, FeS, FeO, and SiO2, is mixed with limestone, which\nserves as a flux (a material that aids in the removal of impurities), and heated. Molten slag forms as the iron\nand silica are removed by Lewis acid-base reactions:\n"]], ["block_7", ["In these reactions, the silicon dioxide behaves as a Lewis acid, which accepts a pair of electrons from the Lewis\nbase (the oxide ion).\n"]], ["block_8", ["Reduction of the Cu2S that remains after smelting is accomplished by blowing air through the molten material.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["LINK TO LEARNING\n"]], ["block_11", [" FIGURE 19.7 \nMolten iron is shown being cast as steel. (credit: Clint Budd)\n"]], ["block_12", [{"image_0": "955_0.png", "coords": [189, 162, 423, 397]}]]], "page_956": [["block_0", ["The air converts part of the Cu2S into Cu2O. As soon as copper(I) oxide is formed, it is reduced by the\nremaining copper(I) sulfide to metallic copper:\n"]], ["block_1", ["The copper obtained in this way is called blister copper because of its characteristic appearance, which is due\nto the air blisters it contains (Figure 19.8). This impure copper is cast into large plates, which are used as\nanodes in the electrolytic refining of the metal (which is described in the chapter on electrochemistry).\n"]], ["block_2", [" FIGURE 19.8 \nBlister copper is obtained during the conversion of copper-containing ore into pure copper. (credit:\n"]], ["block_3", ["\u201cTortie tude\u201d/Wikimedia Commons)\n"]], ["block_4", [" Isolation of Silver \n"]], ["block_5", ["Silver sometimes occurs in large nuggets (Figure 19.9) but more frequently in veins and related deposits. At\none time, panning was an effective method of isolating both silver and gold nuggets. Due to their low reactivity,\nthese metals, and a few others, occur in deposits as nuggets. The discovery of platinum was due to Spanish\nexplorers in Central America mistaking platinum nuggets for silver. When the metal is not in the form of\nnuggets, it often useful to employ a process called hydrometallurgy to separate silver from its ores. Hydrology\ninvolves the separation of a metal from a mixture by first converting it into soluble ions and then extracting\nand reducing them to precipitate the pure metal. In the presence of air, alkali metal cyanides readily form the\n"]], ["block_6", ["soluble dicyanoargentate(I) ion,\nfrom silver metal or silver-containing compounds such as Ag2S\n"]], ["block_7", ["and AgCl. Representative equations are:\n"]], ["block_8", [{"image_0": "956_0.png", "coords": [189, 166, 423, 432]}]], ["block_9", [" 19.1 \u2022 Occurrence, Preparation, and Properties of Transition Metals and Their Compounds \n 943 \n"]]], "page_957": [["block_0", [" 944 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", [" FIGURE 19.9 \nNaturally occurring free silver may be found as nuggets (a) or in veins (b). (credit a: modification of\n"]], ["block_2", ["work by \u201cTeravolt\u201d/Wikimedia Commons; credit b: modification of work by James St. John)\n"]], ["block_3", ["The silver is precipitated from the cyanide solution by the addition of either zinc or iron(II) ions, which serves\nas the reducing agent:\n"]], ["block_4", [" Refining Redox \n"]], ["block_5", ["One of the steps for refining silver involves converting silver into dicyanoargenate(I) ions:\n"]], ["block_6", ["Explain why oxygen must be present to carry out the reaction. Why does the reaction not occur as:\n"]], ["block_7", [" Solution \n"]], ["block_8", ["The charges, as well as the atoms, must balance in reactions. The silver atom is being oxidized from the 0\noxidation state to the 1+ state. Whenever something loses electrons, something must also gain electrons (be\nreduced) to balance the equation. Oxygen is a good oxidizing agent for these reactions because it can gain\nelectrons to go from the 0 oxidation state to the 2\u2212 state.\n"]], ["block_9", [" Check Your Learning \n"]], ["block_10", ["During the refining of iron, carbon must be present in the blast furnace. Why is carbon necessary to convert\niron oxide into iron?\n"]], ["block_11", [" Answer: \nThe carbon is converted into CO, which is the reducing agent that accepts electrons so that iron(III) can be\nreduced to iron(0).\n"]], ["block_12", [" Transition Metal Compounds \n"]], ["block_13", ["The bonding in the simple compounds of the transition elements ranges from ionic to covalent. In their lower\noxidation states, the transition elements form ionic compounds; in their higher oxidation states, they form\ncovalent compounds or polyatomic ions. The variation in oxidation states exhibited by the transition elements\ngives these compounds a metal-based, oxidation-reduction chemistry. The chemistry of several classes of\ncompounds containing elements of the transition series follows.\n"]], ["block_14", [" Halides \nAnhydrous halides of each of the transition elements can be prepared by the direct reaction of the metal with\nhalogens. For example:\n"]], ["block_15", ["Heating a metal halide with additional metal can be used to form a halide of the metal with a lower oxidation\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["EXAMPLE 19.3\n"]], ["block_18", [{"image_0": "957_0.png", "coords": [130, 57, 481, 166]}]]], "page_958": [["block_0", ["state:\n"]], ["block_1", ["The stoichiometry of the metal halide that results from the reaction of the metal with a halogen is determined\nby the relative amounts of metal and halogen and by the strength of the halogen as an oxidizing agent.\nGenerally, fluorine forms fluoride-containing metals in their highest oxidation states. The other halogens may\nnot form analogous compounds.\n"]], ["block_2", ["In general, the preparation of stable water solutions of the halides of the metals of the first transition series is\nby the addition of a hydrohalic acid to carbonates, hydroxides, oxides, or other compounds that contain basic\nanions. Sample reactions are:\n"]], ["block_3", ["Most of the first transition series metals also dissolve in acids, forming a solution of the salt and hydrogen gas.\nFor example:\n"]], ["block_4", ["The polarity of bonds with transition metals varies based not only upon the electronegativities of the atoms\ninvolved but also upon the oxidation state of the transition metal. Remember that bond polarity is a continuous\nspectrum with electrons being shared evenly (covalent bonds) at one extreme and electrons being transferred\ncompletely (ionic bonds) at the other. No bond is ever 100% ionic, and the degree to which the electrons are\nevenly distributed determines many properties of the compound. Transition metal halides with low oxidation\nnumbers form more ionic bonds. For example, titanium(II) chloride and titanium(III) chloride (TiCl2 and TiCl3)\nhave high melting points that are characteristic of ionic compounds, but titanium(IV) chloride (TiCl4) is a\nvolatile liquid, consistent with having covalent titanium-chlorine bonds. All halides of the heavier d-block\nelements have significant covalent characteristics.\n"]], ["block_5", ["The covalent behavior of the transition metals with higher oxidation states is exemplified by the reaction of the\nmetal tetrahalides with water. Like covalent silicon tetrachloride, both the titanium and vanadium tetrahalides\nreact with water to give solutions containing the corresponding hydrohalic acids and the metal oxides:\n"]], ["block_6", [" Oxides \nAs with the halides, the nature of bonding in oxides of the transition elements is determined by the oxidation\nstate of the metal. Oxides with low oxidation states tend to be more ionic, whereas those with higher oxidation\nstates are more covalent. These variations in bonding are because the electronegativities of the elements are\nnot fixed values. The electronegativity of an element increases with increasing oxidation state. Transition\nmetals in low oxidation states have lower electronegativity values than oxygen; therefore, these metal oxides\nare ionic. Transition metals in very high oxidation states have electronegativity values close to that of oxygen,\nwhich leads to these oxides being covalent.\n"]], ["block_7", ["The oxides of the first transition series can be prepared by heating the metals in air. These oxides are Sc2O3,\nTiO2, V2O5, Cr2O3, Mn3O4, Fe3O4, Co3O4, NiO, and CuO.\n"]], ["block_8", ["Alternatively, these oxides and other oxides (with the metals in different oxidation states) can be produced by\nheating the corresponding hydroxides, carbonates, or oxalates in an inert atmosphere. Iron(II) oxide can be\nprepared by heating iron(II) oxalate, and cobalt(II) oxide is produced by heating cobalt(II) hydroxide:\n"]], ["block_9", ["With the exception of CrO3 and Mn2O7, transition metal oxides are not soluble in water. They can react with\nacids and, in a few cases, with bases. Overall, oxides of transition metals with the lowest oxidation states are\nbasic (and react with acids), the intermediate ones are amphoteric, and the highest oxidation states are\n"]], ["block_10", [" 19.1 \u2022 Occurrence, Preparation, and Properties of Transition Metals and Their Compounds \n 945 \n"]]], "page_959": [["block_0", [" 946 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", ["primarily acidic. Basic metal oxides at a low oxidation state react with aqueous acids to form solutions of salts\nand water. Examples include the reaction of cobalt(II) oxide accepting protons from nitric acid, and\nscandium(III) oxide accepting protons from hydrochloric acid:\n"]], ["block_2", ["The oxides of metals with oxidation states of 4+ are amphoteric, and most are not soluble in either acids or\nbases. Vanadium(V) oxide, chromium(VI) oxide, and manganese(VII) oxide are acidic. They react with solutions\nof hydroxides to form salts of the oxyanions\nand\nFor example, the complete ionic\n"]], ["block_3", ["equation for the reaction of chromium(VI) oxide with a strong base is given by:\n"]], ["block_4", ["Chromium(VI) oxide and manganese(VII) oxide react with water to form the acids H2CrO4 and HMnO4,\nrespectively.\n"]], ["block_5", [" Hydroxides \nWhen a soluble hydroxide is added to an aqueous solution of a salt of a transition metal of the first transition\nseries, a gelatinous precipitate forms. For example, adding a solution of sodium hydroxide to a solution of\ncobalt sulfate produces a gelatinous pink or blue precipitate of cobalt(II) hydroxide. The net ionic equation is:\n"]], ["block_6", ["In this and many other cases, these precipitates are hydroxides containing the transition metal ion, hydroxide\nions, and water coordinated to the transition metal. In other cases, the precipitates are hydrated oxides\ncomposed of the metal ion, oxide ions, and water of hydration:\n"]], ["block_7", ["These substances do not contain hydroxide ions. However, both the hydroxides and the hydrated oxides react\nwith acids to form salts and water. When precipitating a metal from solution, it is necessary to avoid an excess\nof hydroxide ion, as this may lead to complex ion formation as discussed later in this chapter. The precipitated\nmetal hydroxides can be separated for further processing or for waste disposal.\n"]], ["block_8", [" Carbonates \nMany of the elements of the first transition series form insoluble carbonates. It is possible to prepare these\ncarbonates by the addition of a soluble carbonate salt to a solution of a transition metal salt. For example,\nnickel carbonate can be prepared from solutions of nickel nitrate and sodium carbonate according to the\nfollowing net ionic equation:\n"]], ["block_9", ["The reactions of the transition metal carbonates are similar to those of the active metal carbonates. They react\nwith acids to form metals salts, carbon dioxide, and water. Upon heating, they decompose, forming the\ntransition metal oxides.\n"]], ["block_10", [" Other Salts \nIn many respects, the chemical behavior of the elements of the first transition series is very similar to that of\nthe main group metals. In particular, the same types of reactions that are used to prepare salts of the main\ngroup metals can be used to prepare simple ionic salts of these elements.\n"]], ["block_11", ["A variety of salts can be prepared from metals that are more active than hydrogen by reaction with the\ncorresponding acids: Scandium metal reacts with hydrobromic acid to form a solution of scandium bromide:\n"]], ["block_12", ["The common compounds that we have just discussed can also be used to prepare salts. The reactions involved\ninclude the reactions of oxides, hydroxides, or carbonates with acids. For example:\n"]], ["block_13", [" Access for free at openstax.org \n"]]], "page_960": [["block_0", ["Substitution reactions involving soluble salts may be used to prepare insoluble salts. For example:\n"]], ["block_1", ["In our discussion of oxides in this section, we have seen that reactions of the covalent oxides of the transition\nelements with hydroxides form salts that contain oxyanions of the transition elements.\n"]], ["block_2", [" High Temperature Superconductors \nA superconductor is a substance that conducts electricity with no resistance. This lack of resistance means\nthat there is no energy loss during the transmission of electricity. This would lead to a significant reduction in\nthe cost of electricity.\n"]], ["block_3", ["Most currently used, commercial superconducting materials, such as NbTi and Nb3Sn, do not become\nsuperconducting until they are cooled below 23 K (\u2212250 \u00b0C). This requires the use of liquid helium, which has a\nboiling temperature of 4 K and is expensive and difficult to handle. The cost of liquid helium has deterred the\nwidespread application of superconductors.\n"]], ["block_4", ["One of the most exciting scientific discoveries of the 1980s was the characterization of compounds that exhibit\nsuperconductivity at temperatures above 90 K. (Compared to liquid helium, 90 K is a high temperature.)\nTypical among the high-temperature superconducting materials are oxides containing yttrium (or one of\nseveral rare earth elements), barium, and copper in a 1:2:3 ratio. The formula of the ionic yttrium compound is\nYBa2Cu3O7.\n"]], ["block_5", ["The new materials become superconducting at temperatures close to 90 K (Figure 19.10), temperatures that\ncan be reached by cooling with liquid nitrogen (boiling temperature of 77 K). Not only are liquid nitrogen-\ncooled materials easier to handle, but the cooling costs are also about 1000 times lower than for liquid helium.\n"]], ["block_6", ["Further advances during the same period included materials that became superconducting at even higher\ntemperatures and with a wider array of materials. The DuPont team led by Uma Chowdry and Arthur Sleight\nidentified Bismouth-Strontium-Copper-Oxides that became superconducting at temperatures as high as 110 K\nand, importantly, did not contain rare earth elements. Advances continued through the subsequent decades\nuntil, in 2020, a team led by Ranga Dias at University of Rochester announced the development of a room-\ntemperature superconductor, opening doors to widespread applications. More research and development is\nneeded to realize the potential of these materials, but the possibilities are very promising.\n"]], ["block_7", [" FIGURE 19.10 \nThe resistance of the high-temperature superconductor YBa2Cu3O7 varies with temperature. Note\n"]], ["block_8", ["how the resistance falls to zero below 92 K, when the substance becomes superconducting.\n"]], ["block_9", ["HOW SCIENCES INTERCONNECT\n"]], ["block_10", [{"image_0": "960_0.png", "coords": [189, 482, 423, 687]}]], ["block_11", [" 19.1 \u2022 Occurrence, Preparation, and Properties of Transition Metals and Their Compounds \n 947 \n"]]], "page_961": [["block_0", [" 948 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", ["Although the brittle, fragile nature of these materials presently hampers their commercial applications, they\nhave tremendous potential that researchers are hard at work improving their processes to help realize.\nSuperconducting transmission lines would carry current for hundreds of miles with no loss of power due to\nresistance in the wires. This could allow generating stations to be located in areas remote from population\ncenters and near the natural resources necessary for power production. The first project demonstrating the\nviability of high-temperature superconductor power transmission was established in New York in 2008.\n"]], ["block_2", ["Researchers are also working on using this technology to develop other applications, such as smaller and more\npowerful microchips. In addition, high-temperature superconductors can be used to generate magnetic fields\nfor applications such as medical devices, magnetic levitation trains, and containment fields for nuclear fusion\nreactors (Figure 19.11).\n"]], ["block_3", [" FIGURE 19.11 \n(a) This magnetic levitation train (or maglev) uses superconductor technology to move along its\n"]], ["block_4", ["tracks. (b) A magnet can be levitated using a dish like this as a superconductor. (credit a: modification of work by\nAlex Needham; credit b: modification of work by Kevin Jarrett)\n"]], ["block_5", ["Watch how a high-temperature superconductor (http://openstax.org/l/16supercond) levitates around a\nmagnetic racetrack in the video.\n"]], ["block_6", [" 19.2 Coordination Chemistry of Transition Metals \n"]], ["block_7", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_8", ["The hemoglobin in your blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the\nmanufacture of polyethylene all contain coordination compounds. Ions of the metals, especially the transition\nmetals, are likely to form complexes. Many of these compounds are highly colored (Figure 19.12). In the\nremainder of this chapter, we will consider the structure and bonding of these remarkable compounds.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["\u2022\nList the defining traits of coordination compounds\n"]], ["block_11", ["\u2022\nDescribe the structures of complexes containing monodentate and polydentate ligands\n"]], ["block_12", ["\u2022\nUse standard nomenclature rules to name coordination compounds\n"]], ["block_13", ["\u2022\nExplain and provide examples of geometric and optical isomerism\n"]], ["block_14", ["\u2022\nIdentify several natural and technological occurrences of coordination compounds\n"]], ["block_15", ["LINK TO LEARNING\n"]], ["block_16", [{"image_0": "961_0.png", "coords": [130, 196, 481, 310]}]]], "page_962": [["block_0", [" FIGURE 19.12 \nMetal ions that contain partially filled d subshell usually form colored complex ions; ions with\n"]], ["block_1", ["empty d subshell (d) or with filled d subshells (d) usually form colorless complexes. This figure shows, from left\nto right, solutions containing [M(H2O)6]ions with M = Sc(d), Cr(d), Co(d), Ni(d), Cu(d), and Zn(d).\n(credit: Sahar Atwa)\n"]], ["block_2", ["Remember that in most main group element compounds, the valence electrons of the isolated atoms combine\nto form chemical bonds that satisfy the octet rule. For instance, the four valence electrons of carbon overlap\nwith electrons from four hydrogen atoms to form CH4. The one valence electron leaves sodium and adds to the\nseven valence electrons of chlorine to form the ionic formula unit NaCl (Figure 19.13). Transition metals do not\nnormally bond in this fashion. They primarily form coordinate covalent bonds, a form of the Lewis acid-base\ninteraction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron\nacceptor (Lewis acid). The Lewis acid in coordination complexes, often called a central metal ion (or atom), is\noften a transition metal or inner transition metal, although main group elements can also form coordination \n compounds . The Lewis base donors, called ligands , can be a wide variety of chemicals\u2014atoms, molecules, or\nions. The only requirement is that they have one or more electron pairs, which can be donated to the central\nmetal. Most often, this involves a donor atom with a lone pair of electrons that can form a coordinate bond to\nthe metal.\n"]], ["block_3", [" FIGURE 19.13 \n(a) Covalent bonds involve the sharing of electrons, and ionic bonds involve the transferring of\n"]], ["block_4", ["electrons associated with each bonding atom, as indicated by the colored electrons. (b) However, coordinate\ncovalent bonds involve electrons from a Lewis base being donated to a metal center. The lone pairs from six water\nmolecules form bonds to the scandium ion to form an octahedral complex. (Only the donated pairs are shown.)\n"]], ["block_5", ["The coordination sphere consists of the central metal ion or atom plus its attached ligands. Brackets in a\nformula enclose the coordination sphere; species outside the brackets are not part of the coordination sphere.\nThe coordination number of the central metal ion or atom is the number of donor atoms bonded to it. The\ncoordination number for the silver ion in [Ag(NH3)2]is two (Figure 19.14). For the copper(II) ion in [CuCl4],\nthe coordination number is four, whereas for the cobalt(II) ion in [Co(H2O)6]the coordination number is six.\nEach of these ligands is monodentate , from the Greek for \u201cone toothed,\u201d meaning that they connect with the\ncentral metal through only one atom. In this case, the number of ligands and the coordination number are\nequal.\n"]], ["block_6", [{"image_0": "962_0.png", "coords": [130, 430, 481, 502]}]], ["block_7", [{"image_1": "962_1.png", "coords": [189, 57, 423, 213]}]], ["block_8", [" 19.2 \u2022 Coordination Chemistry of Transition Metals \n 949 \n"]]], "page_963": [["block_0", [" 950 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", [" FIGURE 19.14 \nThe complexes (a) [Ag(NH3)2], (b) [Cu(Cl)4], and (c) [Co(H2O)6]have coordination numbers of\n"]], ["block_2", ["two, four, and six, respectively. The geometries of these complexes are the same as we have seen with VSEPR\ntheory for main group elements: linear, tetrahedral, and octahedral.\n"]], ["block_3", ["Many other ligands coordinate to the metal in more complex fashions. Bidentate ligands are those in which\ntwo atoms coordinate to the metal center. For example, ethylenediamine (en, H2NCH2CH2NH2) contains two\nnitrogen atoms, each of which has a lone pair and can serve as a Lewis base (Figure 19.15). Both of the atoms\ncan coordinate to a single metal center. In the complex [Co(en)3], there are three bidentate en ligands, and the\ncoordination number of the cobalt(III) ion is six. The most common coordination numbers are two, four, and\nsix, but examples of all coordination numbers from 1 to 15 are known.\n"]], ["block_4", [" FIGURE 19.15 \n(a) The ethylenediamine (en) ligand contains two atoms with lone pairs that can coordinate to the\n"]], ["block_5", ["metal center. (b) The cobalt(III) complex\ncontains three of these ligands, each forming two bonds to\n"]], ["block_6", ["the cobalt ion.\n"]], ["block_7", ["Any ligand that bonds to a central metal ion by more than one donor atom is a polydentate ligand (or \u201cmany\nteeth\u201d) because it can bite into the metal center with more than one bond. The term chelate (pronounced\n\u201cKEY-late\u201d) from the Greek for \u201cclaw\u201d is also used to describe this type of interaction. Many polydentate ligands\nare chelating ligands , and a complex consisting of one or more of these ligands and a central metal is a\nchelate. A chelating ligand is also known as a chelating agent. A chelating ligand holds the metal ion rather like\na crab\u2019s claw would hold a marble. Figure 19.15 showed one example of a chelate. The heme complex in\nhemoglobin is another important example (Figure 19.16). It contains a polydentate ligand with four donor\natoms that coordinate to iron.\n"]], ["block_8", [" FIGURE 19.16 \nThe single ligand heme contains four nitrogen atoms that coordinate to iron in hemoglobin to form a\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", [{"image_0": "963_0.png", "coords": [130, 57, 481, 118]}]], ["block_11", [{"image_1": "963_1.png", "coords": [130, 247, 481, 364]}]], ["block_12", [{"image_2": "963_2.png", "coords": [189, 522, 423, 714]}]]], "page_964": [["block_0", ["chelate.\n"]], ["block_1", ["Polydentate ligands are sometimes identified with prefixes that indicate the number of donor atoms in the\nligand. As we have seen, ligands with one donor atom, such as NH3, Cl, and H2O, are monodentate ligands.\nLigands with two donor groups are bidentate ligands. Ethylenediamine, H2NCH2CH2NH2, and the anion of the\nacid glycine,\n(Figure 19.17) are examples of bidentate ligands. Tridentate ligands, tetradentate\n"]], ["block_2", ["ligands, pentadentate ligands, and hexadentate ligands contain three, four, five, and six donor atoms,\nrespectively. The ligand in heme (Figure 19.16) is a tetradentate ligand.\n"]], ["block_3", [" FIGURE 19.17 \nEach of the anionic ligands shown attaches in a bidentate fashion to platinum(II), with both a\n"]], ["block_4", ["nitrogen and oxygen atom coordinating to the metal.\n"]], ["block_5", [" The Naming of Complexes \n"]], ["block_6", ["The nomenclature of the complexes is patterned after a system suggested by Alfred Werner, a Swiss chemist\nand Nobel laureate, whose outstanding work more than 100 years ago laid the foundation for a clearer\nunderstanding of these compounds. The following five rules are used for naming complexes:\n"]], ["block_7", ["1.\nIf a coordination compound is ionic, name the cation first and the anion second, in accordance with the\nusual nomenclature.\n"]], ["block_8", ["2.\nName the ligands first, followed by the central metal. Name the ligands alphabetically. Negative ligands\n(anions) have names formed by adding -o to the stem name of the group. For examples, see Table 19.1. For\nmost neutral ligands, the name of the molecule is used. The four common exceptions are aqua (H2O),\nammine (NH3), carbonyl (CO), and nitrosyl (NO). For example, name [Pt(NH3)2Cl4] as\ndiamminetetrachloroplatinum(IV).\n"]], ["block_9", [" TABLE 19.1 \n"]], ["block_10", [{"image_0": "964_0.png", "coords": [247, 158, 364, 213]}]], ["block_11", ["Examples of Anionic Ligands\n"]], ["block_12", [" Anionic Ligand \n Name \n"]], ["block_13", ["F\nfluoro\n"]], ["block_14", ["Cl\nchloro\n"]], ["block_15", ["Br\nbromo\n"]], ["block_16", ["I\niodo\n"]], ["block_17", ["CN\ncyano\n"]], ["block_18", ["OH\nhydroxo\n"]], ["block_19", ["O\noxo\n"]], ["block_20", ["nitrato\n"]], ["block_21", ["oxalato\n"]], ["block_22", ["carbonato\n"]], ["block_23", [" 19.2 \u2022 Coordination Chemistry of Transition Metals \n 951 \n"]]], "page_965": [["block_0", [" 952 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", ["When the complex is either a cation or a neutral molecule, the name of the central metal atom is spelled\nexactly like the name of the element and is followed by a Roman numeral in parentheses to indicate its\noxidation state (Table 19.2 and Table 19.3). When the complex is an anion, the suffix -ate is added to the stem\nof the name of the metal, followed by the Roman numeral designation of its oxidation state (Table 19.4).\nSometimes, the Latin name of the metal is used when the English name is clumsy. For example, ferrate is used\ninstead of ironate, plumbate instead leadate, and stannate instead of tinate. The oxidation state of the metal is\ndetermined based on the charges of each ligand and the overall charge of the coordination compound. For\nexample, in [Cr(H2O)4Cl2]Br, the coordination sphere (in brackets) has a charge of 1+ to balance the bromide\nion. The water ligands are neutral, and the chloride ligands are anionic with a charge of 1\u2212 each. To determine\nthe oxidation state of the metal, we set the overall charge equal to the sum of the ligands and the metal: +1 = \u22122\n+ x, so the oxidation state (x) is equal to 3+.\n"]], ["block_2", ["Do you think you understand naming coordination complexes? You can look over more examples and test\n"]], ["block_3", [" Access for free at openstax.org \n"]], ["block_4", ["3.\nIf more than one ligand of a given type is present, the number is indicated by the prefixes di- (for two), tri-\n(for three), tetra- (for four), penta- (for five), and hexa- (for six). Sometimes, the prefixes bis- (for two), tris-\n(for three), and tetrakis- (for four) are used when the name of the ligand already includes di-, tri-, or tetra-,\nor when the ligand name begins with a vowel. For example, the ion bis(bipyridyl)osmium(II) uses bis- to\nsignify that there are two ligands attached to Os, and each bipyridyl ligand contains two pyridine groups\n(C5H4N).\n"]], ["block_5", ["LINK TO LEARNING\n"]], ["block_6", [" TABLE 19.2 \n"]], ["block_7", ["[Co(NH3)6]Cl3\nhexaamminecobalt(III) chloride\n"]], ["block_8", ["[Pt(NH3)4Cl2]\ntetraamminedichloroplatinum(IV) ion\n"]], ["block_9", ["[Ag(NH3)2]\ndiamminesilver(I) ion\n"]], ["block_10", ["[Cr(H2O)4Cl2]Cl\ntetraaquadichlorochromium(III) chloride\n"]], ["block_11", ["[Co(H2NCH2CH2NH2)3]2(SO4)3\ntris(ethylenediamine)cobalt(III) sulfate\n"]], ["block_12", [" TABLE 19.3 \n"]], ["block_13", ["[Pt(NH3)2Cl4]\ndiamminetetrachloroplatinum(IV)\n"]], ["block_14", ["[Ni(H2NCH2CH2NH2)2Cl2]\ndichlorobis(ethylenediamine)nickel(II)\n"]], ["block_15", [" TABLE 19.4 \n"]], ["block_16", ["[PtCl6]\nhexachloroplatinate(IV) ion\n"]], ["block_17", ["Na2[SnCl6]\nsodium hexachlorostannate(IV)\n"]], ["block_18", ["Examples in Which the Complex Is an Anion\n"]], ["block_19", ["Examples in Which the Complex Is a Cation\n"]], ["block_20", ["Examples in Which the Complex Is Neutral\n"]]], "page_966": [["block_0", ["yourself with online quizzes (http://openstax.org/l/16namingcomps) at the University of Sydney\u2019s site.\n"]], ["block_1", [" Coordination Numbers and Oxidation States \n"]], ["block_2", ["Determine the name of the following complexes and give the coordination number of the central metal atom.\n"]], ["block_3", ["(a) Na2[PtCl6]\n"]], ["block_4", ["(b) K3[Fe(C2O4)3]\n"]], ["block_5", ["(c) [Co(NH3)5Cl]Cl2\n"]], ["block_6", [" Solution \n"]], ["block_7", ["(a) There are two Naions, so the coordination sphere has a negative two charge: [PtCl6]. There are six\nanionic chloride ligands, so \u22122 = \u22126 + x, and the oxidation state of the platinum is 4+. The name of the complex\nis sodium hexachloroplatinate(IV), and the coordination number is six. (b) The coordination sphere has a\ncharge of 3\u2212 (based on the potassium) and the oxalate ligands each have a charge of 2\u2212, so the metal oxidation\nstate is given by \u22123 = \u22126 + x, and this is an iron(III) complex. The name is potassium trisoxalatoferrate(III) (note\nthat tris is used instead of tri because the ligand name starts with a vowel). Because oxalate is a bidentate\nligand, this complex has a coordination number of six. (c) In this example, the coordination sphere has a\ncationic charge of 2+. The NH3 ligand is neutral, but the chloro ligand has a charge of 1\u2212. The oxidation state is\nfound by +2 = \u22121 + x and is 3+, so the complex is pentaamminechlorocobalt(III) chloride and the coordination\nnumber is six.\n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["The complex potassium dicyanoargenate(I) is used to make antiseptic compounds. Give the formula and\ncoordination number.\n"]], ["block_10", [" Answer: \nK[Ag(CN)2]; coordination number two\n"]], ["block_11", [" The Structures of Complexes \n"]], ["block_12", ["The most common structures of the complexes in coordination compounds are octahedral, tetrahedral, and\nsquare planar (see Figure 19.18). For transition metal complexes, the coordination number determines the\ngeometry around the central metal ion. Table 19.5 compares coordination numbers to the molecular\ngeometry:\n"]], ["block_13", [" FIGURE 19.18 \nThese are geometries of some complexes with coordination numbers of seven and eight.\n"]], ["block_14", ["EXAMPLE 19.4\n"]], ["block_15", [{"image_0": "966_0.png", "coords": [130, 534, 481, 644]}]], ["block_16", [" 19.2 \u2022 Coordination Chemistry of Transition Metals \n 953 \n"]]], "page_967": [["block_0", [" 954 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", ["Unlike main group atoms in which both the bonding and nonbonding electrons determine the molecular\nshape, the nonbonding d-electrons do not change the arrangement of the ligands. Octahedral complexes have\na coordination number of six, and the six donor atoms are arranged at the corners of an octahedron around\nthe central metal ion. Examples are shown in Figure 19.19. The chloride and nitrate anions in [Co(H2O)6]Cl2\nand [Cr(en)3](NO3)3, and the potassium cations in K2[PtCl6], are outside the brackets and are not bonded to the\nmetal ion.\n"]], ["block_2", [{"image_0": "967_0.png", "coords": [72, 504, 540, 621]}]], ["block_3", [" FIGURE 19.19 \nMany transition metal complexes adopt octahedral geometries, with six donor atoms forming bond\n"]], ["block_4", ["angles of 90\u00b0 about the central atom with adjacent ligands. Note that only ligands within the coordination sphere\naffect the geometry around the metal center.\n"]], ["block_5", ["For transition metals with a coordination number of four, two different geometries are possible: tetrahedral or\nsquare planar. Unlike main group elements, where these geometries can be predicted from VSEPR theory, a\nmore detailed discussion of transition metal orbitals (discussed in the section on Crystal Field Theory) is\nrequired to predict which complexes will be tetrahedral and which will be square planar. In tetrahedral\ncomplexes such as [Zn(CN)4](Figure 19.20), each of the ligand pairs forms an angle of 109.5\u00b0. In square\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [" TABLE 19.5 \n"]], ["block_8", [" Coordination Number \n Molecular Geometry \n Example \n"]], ["block_9", ["2\nlinear\n[Ag(NH3)2]\n"]], ["block_10", ["3\ntrigonal planar\n[Cu(CN)3]\n"]], ["block_11", ["4\ntetrahedral(dor d), low oxidation states for M\n[Ni(CO)4]\n"]], ["block_12", ["4\nsquare planar (d)\n[Ni(CN)4]\n"]], ["block_13", ["5\ntrigonal bipyramidal\n[CoCl5]\n"]], ["block_14", ["5\nsquare pyramidal\n[VO(CN)4]\n"]], ["block_15", ["6\noctahedral\n[CoCl6]\n"]], ["block_16", ["7\npentagonal bipyramid\n[ZrF7]\n"]], ["block_17", ["8\nsquare antiprism\n[ReF8]\n"]], ["block_18", ["8\ndodecahedron\n[Mo(CN)8]\n"]], ["block_19", ["9 and above\nmore complicated structures\n[ReH9]\n"]], ["block_20", ["Coordination Numbers and Molecular Geometry\n"]]], "page_968": [["block_0", ["Isomers are different chemical species that have the same chemical formula. Transition metal complexes\noften exist as geometric isomers , in which the same atoms are connected through the same types of bonds but\nwith differences in their orientation in space. Coordination complexes with two different ligands in the cis and\ntrans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]ion has two\nisomers. In the cis configuration , the two chloride ligands are adjacent to each other (Figure 19.21). The other\nisomer, the trans configuration , has the two chloride ligands directly across from one another.\n"]], ["block_1", ["In the Figure 19.20, the two chlorine ligands occupy cis positions. The other form is shown in Figure 19.22.\nWhen naming specific isomers, the descriptor is listed in front of the name. Therefore, this complex is\ntrans-diamminedichloroplatinum(II).\n"]], ["block_2", ["planar complexes, such as [Pt(NH3)2Cl2], each ligand has two other ligands at 90\u00b0 angles (called the cis\npositions) and one additional ligand at an 180\u00b0 angle, in the trans position.\n"]], ["block_3", [" FIGURE 19.20 \nTransition metals with a coordination number of four can adopt a tetrahedral geometry (a) as in\n"]], ["block_4", ["K2[Zn(CN)4] or a square planar geometry (b) as shown in [Pt(NH3)2Cl2].\n"]], ["block_5", [" Isomerism in Complexes \n"]], ["block_6", [" FIGURE 19.21 \nThe cis and trans isomers of [Co(H2O)4Cl2]contain the same ligands attached to the same metal\n"]], ["block_7", ["ion, but the spatial arrangement causes these two compounds to have very different properties.\n"]], ["block_8", ["Different geometric isomers of a substance are different chemical compounds. They exhibit different\nproperties, even though they have the same formula. For example, the two isomers of [Co(NH3)4Cl2]NO3 differ\nin color; the cis form is violet, and the trans form is green. Furthermore, these isomers have different dipole\nmoments, solubilities, and reactivities. As an example of how the arrangement in space can influence the\nmolecular properties, consider the polarity of the two [Co(NH3)4Cl2]NO3 isomers. Remember that the polarity\nof a molecule or ion is determined by the bond dipoles (which are due to the difference in electronegativity of\nthe bonding atoms) and their arrangement in space. In one isomer, cis chloride ligands cause more electron\ndensity on one side of the molecule than on the other, making it polar. For the trans isomer, each ligand is\ndirectly across from an identical ligand, so the bond dipoles cancel out, and the molecule is nonpolar.\n"]], ["block_9", [" Geometric Isomers \n"]], ["block_10", ["Identify which geometric isomer of [Pt(NH3)2Cl2] is shown in Figure 19.20. Draw the other geometric isomer\nand give its full name.\n"]], ["block_11", [" Solution \n"]], ["block_12", ["EXAMPLE 19.5\n"]], ["block_13", [{"image_0": "968_0.png", "coords": [189, 89, 423, 199]}]], ["block_14", [{"image_1": "968_1.png", "coords": [189, 336, 423, 414]}]], ["block_15", [" 19.2 \u2022 Coordination Chemistry of Transition Metals \n 955 \n"]]], "page_969": [["block_0", [" 956 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["Draw the ion trans-diaqua-trans-dibromo-trans-dichlorocobalt(II).\n"]], ["block_3", [" Answer: \n"]], ["block_4", [{"image_0": "969_0.png", "coords": [72, 161, 189, 225]}]], ["block_5", ["Another important type of isomers are optical isomers , or enantiomers , in which two objects are exact mirror\nimages of each other but cannot be lined up so that all parts match. This means that optical isomers are\nnonsuperimposable mirror images. A classic example of this is a pair of hands, in which the right and left hand\nare mirror images of one another but cannot be superimposed. Optical isomers are very important in organic\nand biochemistry because living systems often incorporate one specific optical isomer and not the other.\nUnlike geometric isomers, pairs of optical isomers have identical properties (boiling point, polarity, solubility,\netc.). Optical isomers differ only in the way they affect polarized light and how they react with other optical\nisomers. For coordination complexes, many coordination compounds such as [M(en)3][in which Mis a\ncentral metal ion such as iron(III) or cobalt(II)] form enantiomers, as shown in Figure 19.23. These two isomers\nwill react differently with other optical isomers. For example, DNA helices are optical isomers, and the form\nthat occurs in nature (right-handed DNA) will bind to only one isomer of [M(en)3]and not the other.\n"]], ["block_6", [" FIGURE 19.23 \nThe complex [M(en)3](M= a metal ion, en = ethylenediamine) has a nonsuperimposable mirror\n"]], ["block_7", ["image.\n"]], ["block_8", ["The [Co(en)2Cl2]ion exhibits geometric isomerism (cis/trans), and its cis isomer exists as a pair of optical\nisomers (Figure 19.24).\n"]], ["block_9", [{"image_1": "969_1.png", "coords": [72, 544, 540, 643]}]], ["block_10", [" FIGURE 19.24 \nThree isomeric forms of [Co(en)2Cl2]exist. The trans isomer, formed when the chlorines are\n"]], ["block_11", ["positioned at a 180\u00b0 angle, has very different properties from the cis isomers. The mirror images of the cis isomer\nform a pair of optical isomers, which have identical behavior except when reacting with other enantiomers.\n"]], ["block_12", [" Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition\nmetal center through two different atoms. For example, the CN ligand can bind through the carbon atom\n(cyano) or through the nitrogen atom (isocyano). Similarly, SCN\u2212 can be bound through the sulfur or nitrogen\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", [" FIGURE 19.22 \nThe trans isomer of [Pt(NH3)2Cl2] has each ligand directly across from an adjacent ligand.\n"]], ["block_15", [{"image_2": "969_2.png", "coords": [130, 387, 481, 478]}]], ["block_16", [{"image_3": "969_3.png", "coords": [247, 57, 364, 90]}]]], "page_970": [["block_0", ["atom, affording two distinct compounds ([Co(NH3)5SCN]or [Co(NH3)5NCS]).\n"]], ["block_1", [" Ionization isomers (or coordination isomers ) occur when one anionic ligand in the inner coordination sphere\nis replaced with the counter ion from the outer coordination sphere. A simple example of two ionization\nisomers are [CoCl6][Br] and [CoCl5Br][Cl].\n"]], ["block_2", [" Coordination Complexes in Nature and Technology \n"]], ["block_3", ["Chlorophyll, the green pigment in plants, is a complex that contains magnesium (Figure 19.25). This is an\nexample of a main group element in a coordination complex. Plants appear green because chlorophyll absorbs\nred and purple light; the reflected light consequently appears green. The energy resulting from the absorption\nof light is used in photosynthesis.\n"]], ["block_4", [{"image_0": "970_0.png", "coords": [72, 197, 540, 367]}]], ["block_5", [" FIGURE 19.25 \n(a) Chlorophyll comes in several different forms, which all have the same basic structure around the\n"]], ["block_6", ["magnesium center. (b) Copper phthalocyanine blue, a square planar copper complex, is present in some blue dyes.\n"]], ["block_7", ["Chemistry in Everyday Life\n"]], ["block_8", [" Transition Metal Catalysts \nOne of the most important applications of transition metals is as industrial catalysts. As you recall from the\nchapter on kinetics, a catalyst increases the rate of reaction by lowering the activation energy and is\nregenerated in the catalytic cycle. Over 90% of all manufactured products are made with the aid of one or\nmore catalysts. The ability to bind ligands and change oxidation states makes transition metal catalysts\nwell suited for catalytic applications. Vanadium oxide is used to produce 230,000,000 tons of sulfuric acid\nworldwide each year, which in turn is used to make everything from fertilizers to cans for food. Plastics are\nmade with the aid of transition metal catalysts, along with detergents, fertilizers, paints, and more (see\nFigure 19.26). Very complicated pharmaceuticals are manufactured with catalysts that are selective,\nreacting with one specific bond out of a large number of possibilities. Catalysts allow processes to be more\neconomical and more environmentally friendly. Developing new catalysts and better understanding of\nexisting systems are important areas of current research.\n"]], ["block_9", [" 19.2 \u2022 Coordination Chemistry of Transition Metals \n 957 \n"]]], "page_971": [["block_0", [" 958 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" FIGURE 19.26 \n(a) Detergents, (b) paints, and (c) fertilizers are all made using transition metal catalysts. (credit\n"]], ["block_3", ["a: modification of work by \u201cMr. Brian\u201d/Flickr; credit b: modification of work by Ewen Roberts; credit c:\nmodification of work by \u201cosseous\u201d/Flickr)\n"]], ["block_4", ["Portrait of a Chemist\n"]], ["block_5", [" Deanna D\u2019Alessandro \nDr. Deanna D\u2019Alessandro develops new metal-containing materials that demonstrate unique electronic,\noptical, and magnetic properties. Her research combines the fields of fundamental inorganic and physical\nchemistry with materials engineering. She is working on many different projects that rely on transition\nmetals. For example, one type of compound she is developing captures carbon dioxide waste from power\nplants and catalytically converts it into useful products (see Figure 19.27).\n"]], ["block_6", [" FIGURE 19.27 \nCatalytic converters change carbon dioxide emissions from power plants into useful products,\n"]], ["block_7", ["and, like the one shown here, are also found in cars.\n"]], ["block_8", ["Another project involves the development of porous, sponge-like materials that are \u201cphotoactive.\u201d The\nabsorption of light causes the pores of the sponge to change size, allowing gas diffusion to be controlled.\nThis has many potential useful applications, from powering cars with hydrogen fuel cells to making better\nelectronics components. Although not a complex, self-darkening sunglasses are an example of a\nphotoactive substance.\n"]], ["block_9", ["Watch this video (http://openstax.org/l/16DeannaD) to learn more about this research and listen to Dr.\nD\u2019Alessandro (shown in Figure 19.28) describe what it is like being a research chemist.\n"]], ["block_10", [{"image_0": "971_0.png", "coords": [90, 57, 522, 202]}]], ["block_11", [{"image_1": "971_1.png", "coords": [148, 380, 463, 572]}]]], "page_972": [["block_0", ["Many other coordination complexes are also brightly colored. The square planar copper(II) complex\nphthalocyanine blue (from Figure 19.25) is one of many complexes used as pigments or dyes. This complex is\nused in blue ink, blue jeans, and certain blue paints.\n"]], ["block_1", ["The structure of heme (Figure 19.29), the iron-containing complex in hemoglobin, is very similar to that in\nchlorophyll. In hemoglobin, the red heme complex is bonded to a large protein molecule (globin) by the\nattachment of the protein to the heme ligand. Oxygen molecules are transported by hemoglobin in the blood by\nbeing bound to the iron center. When the hemoglobin loses its oxygen, the color changes to a bluish red.\nHemoglobin will only transport oxygen if the iron is Fe; oxidation of the iron to Feprevents oxygen\ntransport.\n"]], ["block_2", [" FIGURE 19.28 \nDr. Deanna D\u2019Alessandro is a functional materials researcher. Her work combines the inorganic\n"]], ["block_3", ["and physical chemistry fields with engineering, working with transition metals to create new systems to power\ncars and convert energy (credit: image courtesy of Deanna D'Alessandro).\n"]], ["block_4", [{"image_0": "972_0.png", "coords": [247, 57, 364, 243]}]], ["block_5", [" 19.2 \u2022 Coordination Chemistry of Transition Metals \n 959 \n"]]], "page_973": [["block_0", [" 960 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", [" FIGURE 19.29 \nHemoglobin contains four protein subunits, each of which has an iron center attached to a heme\n"]], ["block_2", ["ligand (shown in red), which is coordinated to a globin protein. Each subunit is shown in a different color.\n"]], ["block_3", ["Complexing agents often are used for water softening because they tie up such ions as Ca, Mg, and Fe,\nwhich make water hard. Many metal ions are also undesirable in food products because these ions can\ncatalyze reactions that change the color of food. Coordination complexes are useful as preservatives. For\nexample, the ligand EDTA, (HO2CCH2)2NCH2CH2N(CH2CO2H)2, coordinates to metal ions through six donor\natoms and prevents the metals from reacting (Figure 19.30). This ligand also is used to sequester metal ions in\npaper production, textiles, and detergents, and has pharmaceutical uses.\n"]], ["block_4", ["Complexing agents that tie up metal ions are also used as drugs. British Anti-Lewisite (BAL),\nHSCH2CH(SH)CH2OH, is a drug developed during World War I as an antidote for the arsenic-based war gas\nLewisite. BAL is now used to treat poisoning by heavy metals, such as arsenic, mercury, thallium, and\nchromium. The drug is a ligand and functions by making a water-soluble chelate of the metal; the kidneys\neliminate this metal chelate (Figure 19.31). Another polydentate ligand, enterobactin, which is isolated from\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", [" FIGURE 19.30 \nThe ligand EDTA binds tightly to a variety of metal ions by forming hexadentate complexes.\n"]], ["block_7", [{"image_0": "973_0.png", "coords": [130, 57, 481, 346]}]], ["block_8", [{"image_1": "973_1.png", "coords": [247, 463, 364, 638]}]]], "page_974": [["block_0", ["certain bacteria, is used to form complexes of iron and thereby to control the severe iron buildup found in\npatients suffering from blood diseases such as Cooley\u2019s anemia, who require frequent transfusions. As the\ntransfused blood breaks down, the usual metabolic processes that remove iron are overloaded, and excess iron\ncan build up to fatal levels. Enterobactin forms a water-soluble complex with excess iron, and the body can\nsafely eliminate this complex.\n"]], ["block_1", [" FIGURE 19.31 \nCoordination complexes are used as drugs. (a) British Anti-Lewisite is used to treat heavy metal\n"]], ["block_2", ["poisoning by coordinating metals (M), and enterobactin (b) allows excess iron in the blood to be removed.\n"]], ["block_3", [" Chelation Therapy \n"]], ["block_4", ["Ligands like BAL and enterobactin are important in medical treatments for heavy metal poisoning. However,\nchelation therapies can disrupt the normal concentration of ions in the body, leading to serious side effects, so\nresearchers are searching for new chelation drugs. One drug that has been developed is dimercaptosuccinic\nacid (DMSA), shown in Figure 19.32. Identify which atoms in this molecule could act as donor atoms.\n"]], ["block_5", [" Solution \n"]], ["block_6", ["All of the oxygen and sulfur atoms have lone pairs of electrons that can be used to coordinate to a metal center,\nso there are six possible donor atoms. Geometrically, only two of these atoms can be coordinated to a metal at\nonce. The most common binding mode involves the coordination of one sulfur atom and one oxygen atom,\nforming a five-member ring with the metal.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["Some alternative medicine practitioners recommend chelation treatments for ailments that are not clearly\nrelated to heavy metals, such as cancer and autism, although the practice is discouraged by many scientific\norganizations.Identify at least two biologically important metals that could be disrupted by chelation therapy.\n"]], ["block_9", ["1 National Council against Health Fraud, NCAHF Policy Statement on Chelation Therapy, (Peabody, MA, 2002).\n"]], ["block_10", ["EXAMPLE 19.6\n"]], ["block_11", [{"image_0": "974_0.png", "coords": [130, 126, 481, 325]}]], ["block_12", [" FIGURE 19.32 \nDimercaptosuccinic acid is used to treat heavy metal poisoning.\n"]], ["block_13", [{"image_1": "974_1.png", "coords": [189, 465, 423, 534]}]], ["block_14", [" 19.2 \u2022 Coordination Chemistry of Transition Metals \n 961 \n"]]], "page_975": [["block_0", [" 962 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", ["In 1965, scientists at Michigan State University discovered that there was a platinum complex that inhibited\ncell division in certain microorganisms. Later work showed that the complex was\ncis-diamminedichloroplatinum(II), [Pt(NH3)2(Cl)2], and that the trans isomer was not effective. The inhibition\nof cell division indicated that this square planar compound could be an anticancer agent. In 1978, the US Food\nand Drug Administration approved this compound, known as cisplatin, for use in the treatment of certain\nforms of cancer. Since that time, many similar platinum compounds have been developed for the treatment of\ncancer. In all cases, these are the cis isomers and never the trans isomers. The diammine (NH3)2 portion is\nretained with other groups, replacing the dichloro [(Cl)2] portion. The newer drugs include carboplatin,\noxaliplatin, and satraplatin.\n"]], ["block_2", [" Answer: \nCa, Fe, Zn, and Cu\n"]], ["block_3", ["Ligands are also used in the electroplating industry. When metal ions are reduced to produce thin metal\ncoatings, metals can clump together to form clusters and nanoparticles. When metal coordination complexes\nare used, the ligands keep the metal atoms isolated from each other. It has been found that many metals plate\nout as a smoother, more uniform, better-looking, and more adherent surface when plated from a bath\ncontaining the metal as a complex ion. Thus, complexes such as [Ag(CN)2]and [Au(CN)2]are used extensively\nin the electroplating industry.\n"]], ["block_4", [" 19.3 Spectroscopic and Magnetic Properties of Coordination Compounds \n"]], ["block_5", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_6", ["The behavior of coordination compounds cannot be adequately explained by the same theories used for main\ngroup element chemistry. The observed geometries of coordination complexes are not consistent with\nhybridized orbitals on the central metal overlapping with ligand orbitals, as would be predicted by valence\nbond theory. The observed colors indicate that the d orbitals often occur at different energy levels rather than\nall being degenerate, that is, of equal energy, as are the three p orbitals. To explain the stabilities, structures,\ncolors, and magnetic properties of transition metal complexes, a different bonding model has been developed.\nJust as valence bond theory explains many aspects of bonding in main group chemistry, crystal field theory is\nuseful in understanding and predicting the behavior of transition metal complexes.\n"]], ["block_7", [" Crystal Field Theory \n"]], ["block_8", ["To explain the observed behavior of transition metal complexes (such as how colors arise), a model involving\nelectrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d\norbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It\nallows us to understand, interpret, and predict the colors, magnetic behavior, and some structures of\ncoordination compounds of transition metals.\n"]], ["block_9", ["CFT focuses on the nonbonding electrons on the central metal ion in coordination complexes not on the metal-\nligand bonds. Like valence bond theory, CFT tells only part of the story of the behavior of complexes. However,\nit tells the part that valence bond theory does not. In its pure form, CFT ignores any covalent bonding between\nligands and metal ions. Both the ligand and the metal are treated as infinitesimally small point charges.\n"]], ["block_10", ["All electrons are negative, so the electrons donated from the ligands will repel the electrons of the central\nmetal. Let us consider the behavior of the electrons in the unhybridized d orbitals in an octahedral complex.\nThe five d orbitals consist of lobe-shaped regions and are arranged in space, as shown in Figure 19.33. In an\noctahedral complex, the six ligands coordinate along the axes.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["\u2022\nOutline the basic premise of crystal field theory (CFT)\n"]], ["block_13", ["\u2022\nIdentify molecular geometries associated with various d-orbital splitting patterns\n"]], ["block_14", ["\u2022\nPredict electron configurations of split d orbitals for selected transition metal atoms or ions\n"]], ["block_15", ["\u2022\nExplain spectral and magnetic properties in terms of CFT concepts\n"]]], "page_976": [["block_0", ["ligands (Figure 19.33). These two orbitals are called the e g orbitals (the symbol actually refers to the symmetry\nof the orbitals, but we will use it as a convenient name for these two orbitals in an octahedral complex). The\nother three orbitals, the dxy, dxz, and dyz orbitals, have lobes that point between the ligands and are called the\n t 2g orbitals (again, the symbol really refers to the symmetry of the orbitals). As six ligands approach the metal\nion along the axes of the octahedron, their point charges repel the electrons in the d orbitals of the metal ion.\nHowever, the repulsions between the electrons in the eg orbitals (the\nand\norbitals) and the ligands\n"]], ["block_1", [{"image_0": "976_0.png", "coords": [72, 57, 540, 195]}]], ["block_2", [" FIGURE 19.33 \nThe directional characteristics of the five d orbitals are shown here. The shaded portions indicate\n"]], ["block_3", ["the phase of the orbitals. The ligands (L) coordinate along the axes. For clarity, the ligands have been omitted from\nthe\norbital so that the axis labels could be shown.\n"]], ["block_4", ["In an uncomplexed metal ion in the gas phase, the electrons are distributed among the five d orbitals in accord\nwith Hund's rule because the orbitals all have the same energy. However, when ligands coordinate to a metal\nion, the energies of the d orbitals are no longer the same.\n"]], ["block_5", ["In octahedral complexes, the lobes in two of the five d orbitals, the\nand\norbitals, point toward the\n"]], ["block_6", ["are greater than the repulsions between the electrons in the t2g orbitals (the dzy, dxz, and dyz orbitals) and the\nligands. This is because the lobes of the eg orbitals point directly at the ligands, whereas the lobes of the t2g\norbitals point between them. Thus, electrons in the eg orbitals of the metal ion in an octahedral complex have\nhigher potential energies than those of electrons in the t2g orbitals. The difference in energy may be\nrepresented as shown in Figure 19.34.\n"]], ["block_7", [" FIGURE 19.34 \nIn octahedral complexes, the eg orbitals are destabilized (higher in energy) compared to the t2g\n"]], ["block_8", ["orbitals because the ligands interact more strongly with the d orbitals at which they are pointed directly.\n"]], ["block_9", ["The difference in energy between the eg and the t2g orbitals is called the crystal field splitting and is\nsymbolized by \u0394 oct , where oct stands for octahedral.\n"]], ["block_10", ["The magnitude of \u0394oct depends on many factors, including the nature of the six ligands located around the\ncentral metal ion, the charge on the metal, and whether the metal is using 3d, 4d, or 5d orbitals. Different\nligands produce different crystal field splittings. The increasing crystal field splitting produced by ligands is\nexpressed in the spectrochemical series , a short version of which is given here:\n"]], ["block_11", [{"image_1": "976_1.png", "coords": [189, 454, 423, 577]}]], ["block_12", [" 19.3 \u2022 Spectroscopic and Magnetic Properties of Coordination Compounds \n 963 \n"]]], "page_977": [["block_0", [" 964 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", ["In this series, ligands on the left cause small crystal field splittings and are weak-field ligands , whereas those\non the right cause larger splittings and are strong-field ligands . Thus, the \u0394oct value for an octahedral complex\nwith iodide ligands (I) is much smaller than the \u0394oct value for the same metal with cyanide ligands (CN).\n"]], ["block_2", ["Electrons in the d orbitals follow the aufbau (\u201cfilling up\u201d) principle, which says that the orbitals will be filled to\ngive the lowest total energy, just as in main group chemistry. When two electrons occupy the same orbital, the\nlike charges repel each other. The energy needed to pair up two electrons in a single orbital is called the\n pairing energy (P) . Electrons will always singly occupy each orbital in a degenerate set before pairing. P is\nsimilar in magnitude to \u0394oct. When electrons fill the d orbitals, the relative magnitudes of \u0394oct and P determine\nwhich orbitals will be occupied.\n"]], ["block_3", ["In [Fe(CN)6], the strong field of six cyanide ligands produces a large \u0394oct. Under these conditions, the\nelectrons require less energy to pair than they require to be excited to the eg orbitals (\u0394oct > P). The six 3d\nelectrons of the Feion pair in the three t2g orbitals (Figure 19.35). Complexes in which the electrons are\npaired because of the large crystal field splitting are called low-spin complexes because the number of\nunpaired electrons (spins) is minimized.\n"]], ["block_4", [{"image_0": "977_0.png", "coords": [72, 252, 540, 412]}]], ["block_5", [" FIGURE 19.35 \nIron(II) complexes have six electrons in the 5d orbitals. In the absence of a crystal field, the\n"]], ["block_6", ["orbitals are degenerate. For coordination complexes with strong-field ligands such as [Fe(CN)6], \u0394oct is greater\nthan P, and the electrons pair in the lower energy t2g orbitals before occupying the eg orbitals. With weak-field\nligands such as H2O, the ligand field splitting is less than the pairing energy, \u0394oct less than P, so the electrons occupy\nall d orbitals singly before any pairing occurs.\n"]], ["block_7", ["In [Fe(H2O)6], on the other hand, the weak field of the water molecules produces only a small crystal field\nsplitting (\u0394oct < P). Because it requires less energy for the electrons to occupy the eg orbitals than to pair\ntogether, there will be an electron in each of the five 3d orbitals before pairing occurs. For the six d electrons on\nthe iron(II) center in [Fe(H2O)6], there will be one pair of electrons and four unpaired electrons (Figure\n19.35). Complexes such as the [Fe(H2O)6]ion, in which the electrons are unpaired because the crystal field\nsplitting is not large enough to cause them to pair, are called high-spin complexes because the number of\nunpaired electrons (spins) is maximized.\n"]], ["block_8", ["A similar line of reasoning shows why the [Fe(CN)6]ion is a low-spin complex with only one unpaired\nelectron, whereas both the [Fe(H2O)6]and [FeF6]ions are high-spin complexes with five unpaired electrons.\n"]], ["block_9", [" High- and Low-Spin Complexes \n"]], ["block_10", ["Predict the number of unpaired electrons.\n"]], ["block_11", ["(a) K3[CrI6]\n"]], ["block_12", ["(b) [Cu(en)2(H2O)2]Cl2\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", ["EXAMPLE 19.7\n"]]], "page_978": [["block_0", [" Answer: \nd, d, d, and d\n"]], ["block_1", ["(c) Na3[Co(NO2)6]\n"]], ["block_2", [" Solution \n"]], ["block_3", ["The complexes are octahedral.\n"]], ["block_4", ["(a) Crhas a dconfiguration. These electrons will all be unpaired.\n"]], ["block_5", ["(b) Cuis d, so there will be one unpaired electron.\n"]], ["block_6", ["(c) Cohas dvalence electrons, so the crystal field splitting will determine how many are paired. Nitrite is a\nstrong-field ligand, so the complex will be low spin. Six electrons will go in the t2g orbitals, leaving 0 unpaired.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["The size of the crystal field splitting only influences the arrangement of electrons when there is a choice\nbetween pairing electrons and filling the higher-energy orbitals. For which d-electron configurations will there\nbe a difference between high- and low-spin configurations in octahedral complexes?\n"]], ["block_9", [" CFT for Other Geometries \n"]], ["block_10", ["CFT is applicable to molecules in geometries other than octahedral. In octahedral complexes, remember that\nthe lobes of the eg set point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place,\nbut now we have only four ligands located between the axes (Figure 19.36). None of the orbitals points directly\nat the tetrahedral ligands. However, the eg set (along the Cartesian axes) overlaps with the ligands less than\ndoes the t2g set. By analogy with the octahedral case, predict the energy diagram for the d orbitals in a\ntetrahedral crystal field. To avoid confusion, the octahedral eg set becomes a tetrahedral e set, and the\noctahedral t2g set becomes a t2 set.\n"]], ["block_11", [" FIGURE 19.36 \nThis diagram shows the orientation of the tetrahedral ligands with respect to the axis system for the\n"]], ["block_12", ["orbitals.\n"]], ["block_13", [" Solution \n"]], ["block_14", ["Since CFT is based on electrostatic repulsion, the orbitals closer to the ligands will be destabilized and raised\nin energy relative to the other set of orbitals. The splitting is less than for octahedral complexes because the\noverlap is less, so \u0394tet is usually small\n"]], ["block_15", ["EXAMPLE 19.8\n"]], ["block_16", [{"image_0": "978_0.png", "coords": [189, 430, 423, 584]}]], ["block_17", [" 19.3 \u2022 Spectroscopic and Magnetic Properties of Coordination Compounds \n 965 \n"]]], "page_979": [["block_0", [" 966 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", ["The other common geometry is square planar. It is possible to consider a square planar geometry as an\noctahedral structure with a pair of trans ligands removed. The removed ligands are assumed to be on the\nz-axis. This changes the distribution of the d orbitals, as orbitals on or near the z-axis become more stable, and\nthose on or near the x- or y-axes become less stable. This results in the octahedral t2g and the eg sets splitting\nand gives a more complicated pattern, as depicted below:\n"]], ["block_2", [{"image_0": "979_0.png", "coords": [72, 57, 306, 168]}]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["Explain how many unpaired electrons a tetrahedral dion will have.\n"]], ["block_5", [" Answer: \n4; because \u0394tet is small, all tetrahedral complexes are high spin and the electrons go into the t2 orbitals before\npairing\n"]], ["block_6", [" Access for free at openstax.org \n"]]], "page_980": [["block_0", [{"image_0": "980_0.png", "coords": [72, 57, 278, 568]}]], ["block_1", [" Magnetic Moments of Molecules and Ions \n"]], ["block_2", ["Experimental evidence of magnetic measurements supports the theory of high- and low-spin complexes.\nRemember that molecules such as O2 that contain unpaired electrons are paramagnetic. Paramagnetic\nsubstances are attracted to magnetic fields. Many transition metal complexes have unpaired electrons and\nhence are paramagnetic. Molecules such as N2 and ions such as Naand [Fe(CN)6]that contain no unpaired\nelectrons are diamagnetic. Diamagnetic substances have a slight tendency to be repelled by magnetic fields.\n"]], ["block_3", ["When an electron in an atom or ion is unpaired, the magnetic moment due to its spin makes the entire atom or\nion paramagnetic. The size of the magnetic moment of a system containing unpaired electrons is related\ndirectly to the number of such electrons: the greater the number of unpaired electrons, the larger the magnetic\nmoment. Therefore, the observed magnetic moment is used to determine the number of unpaired electrons\npresent. The measured magnetic moment of low-spin d[Fe(CN)6]confirms that iron is diamagnetic,\n"]], ["block_4", [" 19.3 \u2022 Spectroscopic and Magnetic Properties of Coordination Compounds \n 967 \n"]]], "page_981": [["block_0", [" 968 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", ["whereas high-spin d[Fe(H2O)6]has four unpaired electrons with a magnetic moment that confirms this\narrangement.\n"]], ["block_2", [" Colors of Transition Metal Complexes \n"]], ["block_3", ["When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy\norbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the\nelectromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the\nenergy difference between the d orbitals often allows photons in the visible range to be absorbed.\n"]], ["block_4", ["The human eye perceives a mixture of all the colors, in the proportions present in sunlight, as white light.\nComplementary colors, those located across from each other on a color wheel, are also used in color vision.\nThe eye perceives a mixture of two complementary colors, in the proper proportions, as white light. Likewise,\nwhen a color is missing from white light, the eye sees its complement. For example, when red photons are\nabsorbed from white light, the eyes see the color green. When violet photons are removed from white light, the\neyes see lemon yellow. The blue color of the [Cu(NH3)4]ion results because this ion absorbs orange and red\nlight, leaving the complementary colors of blue and green (Figure 19.37).\n"]], ["block_5", [{"image_0": "981_0.png", "coords": [72, 260, 540, 633]}]], ["block_6", [" FIGURE 19.37 \n(a) An object is black if it absorbs all colors of light. If it reflects all colors of light, it is white. An\n"]], ["block_7", ["object has a color if it absorbs all colors except one, such as this yellow strip. The strip also appears yellow if it\nabsorbs the complementary color from white light (in this case, indigo). (b) Complementary colors are located\ndirectly across from one another on the color wheel. (c) A solution of [Cu(NH3)4]ions absorbs red and orange light,\nso the transmitted light appears as the complementary color, blue.\n"]], ["block_8", [" Access for free at openstax.org \n"]]], "page_982": [["block_0", [" Colors of Complexes \n"]], ["block_1", ["The octahedral complex [Ti(H2O)6]has a single d electron. To excite this electron from the ground state t2g\norbital to the eg orbital, this complex absorbs light from 450 to 600 nm. The maximum absorbance\ncorresponds to \u0394oct and occurs at 499 nm. Calculate the value of \u0394oct in Joules and predict what color the\nsolution will appear.\n"]], ["block_2", [" Solution \n"]], ["block_3", ["Using Planck's equation (refer to the section on electromagnetic energy), we calculate:\n"]], ["block_4", ["Because the complex absorbs 600 nm (orange) through 450 (blue), the indigo, violet, and red wavelengths will\nbe transmitted, and the complex will appear purple.\n"]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["A complex that appears green, absorbs photons of what wavelengths?\n"]], ["block_7", [" Answer: \nred, 620\u2013800 nm\n"]], ["block_8", ["Small changes in the relative energies of the orbitals that electrons are transitioning between can lead to\ndrastic shifts in the color of light absorbed. Therefore, the colors of coordination compounds depend on many\nfactors. As shown in Figure 19.38, different aqueous metal ions can have different colors. In addition, different\noxidation states of one metal can produce different colors, as shown for the vanadium complexes in the link\nbelow.\n"]], ["block_9", [" FIGURE 19.38 \nThe partially filled d orbitals of the stable ions Cr(aq), Fe(aq), and Co(aq) (left, center and\n"]], ["block_10", ["right, respectively) give rise to various colors. (credit: Sahar Atwa)\n"]], ["block_11", ["The specific ligands coordinated to the metal center also influence the color of coordination complexes. For\nexample, the iron(II) complex [Fe(H2O)6]SO4 appears blue-green because the high-spin complex absorbs\nphotons in the red wavelengths (Figure 19.39). In contrast, the low-spin iron(II) complex K4[Fe(CN)6] appears\npale yellow because it absorbs higher-energy violet photons.\n"]], ["block_12", ["EXAMPLE 19.9\n"]], ["block_13", [{"image_0": "982_0.png", "coords": [189, 438, 423, 593]}]], ["block_14", [" 19.3 \u2022 Spectroscopic and Magnetic Properties of Coordination Compounds \n 969 \n"]]], "page_983": [["block_0", [" 970 \n 19 \u2022 Transition Metals and Coordination Chemistry \n"]], ["block_1", [" FIGURE 19.39 \nBoth (a) hexaaquairon(II) sulfate and (b) potassium hexacyanoferrate(II) contain diron(II)\n"]], ["block_2", ["octahedral metal centers, but they absorb photons in different ranges of the visible spectrum.\n"]], ["block_3", ["Watch this video (http://openstax.org/l/16vanadium) of the reduction of vanadium complexes to observe the\ncolorful effect of changing oxidation states.\n"]], ["block_4", ["In general, strong-field ligands cause a large split in the energies of d orbitals of the central metal atom (large\n\u0394oct). Transition metal coordination compounds with these ligands are yellow, orange, or red because they\nabsorb higher-energy violet or blue light. On the other hand, coordination compounds of transition metals with\nweak-field ligands are often blue-green, blue, or indigo because they absorb lower-energy yellow, orange, or\nred light.\n"]], ["block_5", ["A coordination compound of the Cuion has a dconfiguration, and all the eg orbitals are filled. To excite an\nelectron to a higher level, such as the 4p orbital, photons of very high energy are necessary. This energy\ncorresponds to very short wavelengths in the ultraviolet region of the spectrum. No visible light is absorbed, so\nthe eye sees no change, and the compound appears white or colorless. A solution containing [Cu(CN)2], for\nexample, is colorless. On the other hand, octahedral Cucomplexes have a vacancy in the eg orbitals, and\nelectrons can be excited to this level. The wavelength (energy) of the light absorbed corresponds to the visible\npart of the spectrum, and Cucomplexes are almost always colored\u2014blue, blue-green violet, or yellow (Figure\n19.40). Although CFT successfully describes many properties of coordination complexes, molecular orbital\nexplanations (beyond the introductory scope provided here) are required to understand fully the behavior of\ncoordination complexes.\n"]], ["block_6", [" FIGURE 19.40 \n(a) Copper(I) complexes with dconfigurations such as CuI tend to be colorless, whereas (b) d\n"]], ["block_7", ["copper(II) complexes such as Cu(NO3)2\u00b75H2O are brightly colored.\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["LINK TO LEARNING\n"]], ["block_10", [{"image_0": "983_0.png", "coords": [130, 57, 481, 198]}]], ["block_11", [{"image_1": "983_1.png", "coords": [130, 500, 481, 655]}]]], "page_984": [["block_0", [" cis configuration \nconfiguration of a geometrical\n"]], ["block_1", [" d-block element \none of the elements in groups\n"]], ["block_2", [" e g orbitals \nset of two d orbitals that are oriented on\n"]], ["block_3", [" f-block element \n(also, inner transition element)\n"]], ["block_4", [" Key Terms \n"]], ["block_5", [" actinide series \n(also, actinoid series) actinium and\n"]], ["block_6", [" bidentate ligand \nligand that coordinates to one\n"]], ["block_7", [" central metal \nion or atom to which one or more\n"]], ["block_8", [" chelate \ncomplex formed from a polydentate ligand\n"]], ["block_9", [" chelating ligand \nligand that attaches to a central\n"]], ["block_10", [" coordination compound \nstable compound in\n"]], ["block_11", [" coordination compound \nsubstance consisting of\n"]], ["block_12", [" coordination number \nnumber of coordinate\n"]], ["block_13", [" coordination sphere \ncentral metal atom or ion\n"]], ["block_14", [" crystal field splitting ( \u0394 oct ) \ndifference in energy\n"]], ["block_15", [" crystal field theory \nmodel that explains the\n"]], ["block_16", [" donor atom \natom in a ligand with a lone pair of\n"]], ["block_17", ["the elements in the second row or the f-block,\natomic numbers 89\u2013103\n"]], ["block_18", ["central metal through coordinate bonds from two\ndifferent atoms\n"]], ["block_19", ["ligands is attached through coordinate covalent\nbonds\n"]], ["block_20", ["attached to a central metal\n"]], ["block_21", ["metal ion by bonds from two or more donor\natoms\n"]], ["block_22", ["isomer in which two similar groups are on the\nsame side of an imaginary reference line on the\nmolecule\n"]], ["block_23", ["which the central metal atom or ion acts as a\nLewis acid and accepts one or more pairs of\nelectrons\n"]], ["block_24", ["atoms, molecules, or ions attached to a central\natom through Lewis acid-base interactions\n"]], ["block_25", ["covalent bonds to the central metal atom in a\ncomplex or the number of closest contacts to an\natom in a crystalline form\n"]], ["block_26", ["plus the attached ligands of a complex\n"]], ["block_27", ["between the t2g and eg sets or t and e sets of\norbitals\n"]], ["block_28", ["energies of the orbitals in transition metals in\nterms of electrostatic interactions with the\nligands but does not include metal ligand\nbonding\n"]], ["block_29", ["3\u201311 with valence electrons in d orbitals\n"]], ["block_30", ["electrons that forms a coordinate covalent bond\nto a central metal\n"]], ["block_31", ["the Cartesian axes for coordination complexes; in\noctahedral complexes, they are higher in energy\nthan the t2g orbitals\n"]], ["block_32", ["one of the elements with atomic numbers 58\u201371\nor 90\u2013103 that have valence electrons in f\norbitals; they are frequently shown offset below\n"]], ["block_33", [" first transition series \ntransition elements in the\n"]], ["block_34", [" fourth transition series \ntransition elements in the\n"]], ["block_35", [" geometric isomers \nisomers that differ in the way\n"]], ["block_36", [" high-spin complex \ncomplex in which the electrons\n"]], ["block_37", [" hydrometallurgy \nprocess in which a metal is\n"]], ["block_38", [" ionization isomer \n(or coordination isomer) isomer\n"]], ["block_39", [" lanthanide series \n(also, lanthanoid series)\n"]], ["block_40", [" ligand \nion or neutral molecule attached to the\n"]], ["block_41", [" linkage isomer \ncoordination compound that\n"]], ["block_42", [" low-spin complex \ncomplex in which the electrons\n"]], ["block_43", [" monodentate \nligand that attaches to a central\n"]], ["block_44", [" optical isomer \n(also, enantiomer) molecule that is\n"]], ["block_45", [" pairing energy (P) \nenergy required to place two\n"]], ["block_46", [" platinum metals \ngroup of six transition metals\n"]], ["block_47", [" polydentate ligand \nligand that is attached to a\n"]], ["block_48", ["fourth period of the periodic table (first row of the\nd-block), atomic numbers 21\u201329\n"]], ["block_49", ["the periodic table\n"]], ["block_50", ["seventh period of the periodic table (fourth row of\nthe d-block), atomic numbers 89 and 104\u2013111\n"]], ["block_51", ["in which atoms are oriented in space relative to\neach other, leading to different physical and\nchemical properties\n"]], ["block_52", ["maximize the total electron spin by singly\npopulating all of the orbitals before pairing two\nelectrons into the lower-energy orbitals\n"]], ["block_53", ["separated from a mixture by first converting it\ninto soluble ions, extracting the ions, and then\nreducing the ions to precipitate the pure metal\n"]], ["block_54", ["in which an anionic ligand is replaced by the\ncounter ion in the inner coordination sphere\n"]], ["block_55", ["lanthanum and the elements in the first row or\nthe f-block, atomic numbers 57\u201371\n"]], ["block_56", ["central metal ion in a coordination compound\n"]], ["block_57", ["possesses a ligand that can bind to the transition\nmetal in two different ways (CNvs. NC)\n"]], ["block_58", ["minimize the total electron spin by pairing in the\nlower-energy orbitals before populating the\nhigher-energy orbitals\n"]], ["block_59", ["metal through just one coordinate covalent bond\n"]], ["block_60", ["a nonsuperimposable mirror image with identical\nchemical and physical properties, except when it\nreacts with other optical isomers\n"]], ["block_61", ["electrons with opposite spins into a single orbital\n"]], ["block_62", ["consisting of ruthenium, osmium, rhodium,\niridium, palladium, and platinum that tend to\noccur in the same minerals and demonstrate\nsimilar chemical properties\n"]], ["block_63", ["central metal ion by bonds from two or more\ndonor atoms, named with prefixes specifying how\nmany donors are present (e.g., hexadentate = six\ncoordinate bonds formed)\n"]], ["block_64", [" 19 \u2022 Key Terms \n 971 \n"]]], "page_985": [["block_0", [" 972 \n 19 \u2022 Summary \n"]], ["block_1", [" rare earth element \ncollection of 17 elements\n"]], ["block_2", [" second transition series \ntransition elements in\n"]], ["block_3", [" smelting \nprocess of extracting a pure metal from a\n"]], ["block_4", [" spectrochemical series \nranking of ligands\n"]], ["block_5", [" steel \nmaterial made from iron by removing\n"]], ["block_6", [" strong-field ligand \nligand that causes larger\n"]], ["block_7", [" Summary \n"]], ["block_8", [" 19.1 Occurrence, Preparation, and \n Properties of Transition Metals and Their \n Compounds \n"]], ["block_9", ["The transition metals are elements with partially\nfilled d orbitals, located in the d-block of the periodic\ntable. The reactivity of the transition elements varies\nwidely from very active metals such as scandium\nand iron to almost inert elements, such as the\nplatinum metals. The type of chemistry used in the\nisolation of the elements from their ores depends\nupon the concentration of the element in its ore and\nthe difficulty of reducing ions of the elements to the\nmetals. Metals that are more active are more difficult\nto reduce.\n"]], ["block_10", ["Transition metals exhibit chemical behavior typical\nof metals. For example, they oxidize in air upon\nheating and react with elemental halogens to form\nhalides. Those elements that lie above hydrogen in\nthe activity series react with acids, producing salts\nand hydrogen gas. Oxides, hydroxides, and\ncarbonates of transition metal compounds in low\noxidation states are basic. Halides and other salts\nare generally stable in water, although oxygen must\nbe excluded in some cases. Most transition metals\nform a variety of stable oxidation states, allowing\nthem to demonstrate a wide range of chemical\nreactivity.\n"]], ["block_11", [" 19.2 Coordination Chemistry of Transition \n Metals \n"]], ["block_12", ["The transition elements and main group elements\ncan form coordination compounds, or complexes, in\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", ["including the lanthanides, scandium, and yttrium\nthat often occur together and have similar\nchemical properties, making separation difficult\n"]], ["block_15", ["the fifth period of the periodic table (second row\nof the d-block), atomic numbers 39\u201347\n"]], ["block_16", ["molten ore\n"]], ["block_17", ["according to the magnitude of the crystal field\nsplitting they induce\n"]], ["block_18", ["impurities in the iron and adding substances that\nproduce alloys with properties suitable for\nspecific uses\n"]], ["block_19", [" t 2g orbitals \nset of three d orbitals aligned between\n"]], ["block_20", [" trans configuration \nconfiguration of a geometrical\n"]], ["block_21", [" superconductor \nmaterial that conducts electricity\n"]], ["block_22", [" third transition series \ntransition elements in the\n"]], ["block_23", [" weak-field ligand \nligand that causes small crystal\n"]], ["block_24", ["which a central metal atom or ion is bonded to one\nor more ligands by coordinate covalent bonds.\nLigands with more than one donor atom are called\npolydentate ligands and form chelates. The common\ngeometries found in complexes are tetrahedral and\nsquare planar (both with a coordination number of\nfour) and octahedral (with a coordination number of\nsix). Cis and trans configurations are possible in\nsome octahedral and square planar complexes. In\naddition to these geometrical isomers, optical\nisomers (molecules or ions that are mirror images\nbut not superimposable) are possible in certain\noctahedral complexes. Coordination complexes have\na wide variety of uses including oxygen transport in\nblood, water purification, and pharmaceutical use.\n"]], ["block_25", [" 19.3 Spectroscopic and Magnetic Properties \n of Coordination Compounds \n"]], ["block_26", ["Crystal field theory treats interactions between the\nelectrons on the metal and the ligands as a simple\nelectrostatic effect. The presence of the ligands near\nthe metal ion changes the energies of the metal d\norbitals relative to their energies in the free ion. Both\nthe color and the magnetic properties of a complex\ncan be attributed to this crystal field splitting. The\nmagnitude of the splitting (\u0394oct) depends on the\nnature of the ligands bonded to the metal. Strong-\nfield ligands produce large splitting and favor low-\nspin complexes, in which the t2g orbitals are\ncompletely filled before any electrons occupy the eg\norbitals. Weak-field ligands favor formation of high-\nspin complexes. The t2g and the eg orbitals are singly\noccupied before any are doubly occupied.\n"]], ["block_27", ["sixth period of the periodic table (third row of the\nd-block), atomic numbers 57 and 72\u201379\n"]], ["block_28", ["crystal field splittings\n"]], ["block_29", ["with no resistance\n"]], ["block_30", ["the Cartesian axes for coordination complexes; in\noctahedral complexes, they are lowered in energy\ncompared to the eg orbitals according to CFT\n"]], ["block_31", ["isomer in which two similar groups are on\nopposite sides of an imaginary reference line on\nthe molecule\n"]], ["block_32", ["field splittings\n"]]], "page_986": [["block_0", [" Exercises \n"]], ["block_1", [" 19.1 Occurrence, Preparation, and Properties of Transition Metals and Their Compounds \n"]], ["block_2", [" 9 . Why is the formation of slag useful during the smelting of iron?\n 10 . Would you expect an aqueous manganese(VII) oxide solution to have a pH greater or less than 7.0? Justify\n"]], ["block_3", [" 11 . Iron(II) can be oxidized to iron(III) by dichromate ion, which is reduced to chromium(III) in acid solution.\n"]], ["block_4", [" 12 . How many cubic feet of air at a pressure of 760 torr and 0 \u00b0C is required per ton of Fe2O3 to convert that\n"]], ["block_5", [" 13 . Find the potentials of the following electrochemical cell:\n"]], ["block_6", [" 14 . A 2.5624-g sample of a pure solid alkali metal chloride is dissolved in water and treated with excess silver\n"]], ["block_7", [" 15 . The standard reduction potential for the reaction\nis\n"]], ["block_8", [" 1 . Write the electron configurations for each of the following elements:\n"]], ["block_9", [" 2 . Write the electron configurations for each of the following elements and its ions:\n"]], ["block_10", [" 3 . Write the electron configurations for each of the following elements and its 3+ ions:\n"]], ["block_11", [" 4 . Why are the lanthanoid elements not found in nature in their elemental forms?\n 5 . Which of the following elements is most likely to be used to prepare La by the reduction of La2O3: Al, C, or\n"]], ["block_12", [" 6 . Which of the following is the strongest oxidizing agent:\nor\n"]], ["block_13", [" 7 . Which of the following elements is most likely to form an oxide with the formula MO3: Zr, Nb, or Mo?\n 8 . The following reactions all occur in a blast furnace. Which of these are redox reactions?\n"]], ["block_14", ["(a) Sc\n(b) Ti\n(c) Cr\n(d) Fe\n(e) Ru\n"]], ["block_15", ["(a) Ti\n(b) Ti\n"]], ["block_16", ["(c) Ti\n"]], ["block_17", ["(d) Ti\n"]], ["block_18", ["(a) La\n(b) Sm\n(c) Lu\n"]], ["block_19", ["Fe? Why?\n"]], ["block_20", ["(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n(g)\n"]], ["block_21", ["A 2.5000-g sample of iron ore is dissolved and the iron converted into iron(II). Exactly 19.17 mL of 0.0100\nM Na2Cr2O7 is required in the titration. What percentage of the ore sample was iron?\n"]], ["block_22", ["your answer.\n"]], ["block_23", ["Fe2O3 into iron in a blast furnace? For this exercise, assume air is 19% oxygen by volume.\n"]], ["block_24", ["Cd | Cd, M = 0.10 \u2016 Ni, M = 0.50 | Ni\n"]], ["block_25", ["nitrate. The resulting precipitate, filtered and dried, weighs 3.03707 g. What was the percent by mass of\nchloride ion in the original compound? What is the identity of the salt?\n"]], ["block_26", ["about 1.8 V. The reduction potential for the reaction\nis\n"]], ["block_27", ["+0.1 V. Calculate the cell potentials to show whether the complex ions, [Co(H2O)6]and/or [Co(NH3)6],\ncan be oxidized to the corresponding cobalt(III) complex by oxygen.\n"]], ["block_28", [" 19 \u2022 Exercises \n 973 \n"]]], "page_987": [["block_0", [" 974 \n 19 \u2022 Exercises \n"]], ["block_1", [" 16 . Predict the products of each of the following reactions. (Note: In addition to using the information in this\n"]], ["block_2", [" 17 . Predict the products of each of the following reactions. (Note: In addition to using the information in this\n"]], ["block_3", [" 18 . Describe the electrolytic process for refining copper.\n 19 . Predict the products of the following reactions and balance the equations.\n"]], ["block_4", [" 20 . What is the gas produced when iron(II) sulfide is treated with a nonoxidizing acid?\n 21 . Predict the products of each of the following reactions and then balance the chemical equations.\n"]], ["block_5", [" 22 . Balance the following equations by oxidation-reduction methods; note that three elements change\n"]], ["block_6", [" 23 . Dilute sodium cyanide solution is slowly dripped into a slowly stirred silver nitrate solution. A white\n"]], ["block_7", [" 24 . Predict which will be more stable, [CrO4]or [WO4], and explain.\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["chapter, also use the knowledge you have accumulated at this stage of your study, including information\non the prediction of reaction products.)\n(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n"]], ["block_10", ["chapter, also use the knowledge you have accumulated at this stage of your study, including information\non the prediction of reaction products.)\n(a)\n(b)\n(c)\n(d)\n(e)\n(f)\n"]], ["block_11", ["(a) Zn is added to a solution of Cr2(SO4)3 in acid.\n(b) FeCl2 is added to a solution containing an excess of\nin hydrochloric acid.\n"]], ["block_12", ["(c) Cris added to\nin acid solution.\n"]], ["block_13", ["(d) Mn is heated with CrO3.\n(e) CrO is added to 2HNO3 in water.\n(f) FeCl3 is added to an aqueous solution of NaOH.\n"]], ["block_14", ["(a) Fe is heated in an atmosphere of steam.\n(b) NaOH is added to a solution of Fe(NO3)3.\n(c) FeSO4 is added to an acidic solution of KMnO4.\n(d) Fe is added to a dilute solution of H2SO4.\n(e) A solution of Fe(NO3)2 and HNO3 is allowed to stand in air.\n(f) FeCO3 is added to a solution of HClO4.\n(g) Fe is heated in air.\n"]], ["block_15", ["oxidation state.\n"]], ["block_16", ["precipitate forms temporarily but dissolves as the addition of sodium cyanide continues. Use chemical\nequations to explain this observation. Silver cyanide is similar to silver chloride in its solubility.\n"]]], "page_988": [["block_0", [" 25 . Give the oxidation state of the metal for each of the following oxides of the first transition series. (Hint:\n"]], ["block_1", [" 19.2 Coordination Chemistry of Transition Metals \n"]], ["block_2", [" 26 . Indicate the coordination number for the central metal atom in each of the following coordination\n"]], ["block_3", [" 27 . Give the coordination numbers and write the formulas for each of the following, including all isomers\n"]], ["block_4", [" 28 . Give the coordination number for each metal ion in the following compounds:\n"]], ["block_5", [" 29 . Sketch the structures of the following complexes. Indicate any cis, trans, and optical isomers.\n"]], ["block_6", ["Oxides of formula M3O4 are examples of mixed valence compounds in which the metal ion is present in\nmore than one oxidation state. It is possible to write these compound formulas in the equivalent format\nMO\u00b7M2O3, to permit estimation of the metal\u2019s two oxidation states.)\n(a) Sc2O3\n(b) TiO2\n(c) V2O5\n(d) CrO3\n(e) MnO2\n(f) Fe3O4\n(g) Co3O4\n(h) NiO\n(i) Cu2O\n"]], ["block_7", ["compounds:\n(a) [Pt(H2O)2Br2]\n(b) [Pt(NH3)(py)(Cl)(Br)] (py = pyridine, C5H5N)\n(c) [Zn(NH3)2Cl2]\n(d) [Zn(NH3)(py)(Cl)(Br)]\n(e) [Ni(H2O)4Cl2]\n(f) [Fe(en)2(CN)2](en = ethylenediamine, C2H8N2)\n"]], ["block_8", ["where appropriate:\n(a) tetrahydroxozincate(II) ion (tetrahedral)\n(b) hexacyanopalladate(IV) ion\n(c) dichloroaurate(I) ion (note that aurum is Latin for \"gold\")\n(d) diamminedichloroplatinum(II)\n(e) potassium diamminetetrachlorochromate(III)\n(f) hexaamminecobalt(III) hexacyanochromate(III)\n(g) dibromobis(ethylenediamine) cobalt(III) nitrate\n"]], ["block_9", ["(a) [Co(CO3)3](note that CO3is bidentate in this complex)\n(b) [Cu(NH3)4]\n"]], ["block_10", ["(c) [Co(NH3)4Br2]2(SO4)3\n(d) [Pt(NH3)4][PtCl4]\n(e) [Cr(en)3](NO3)3\n(f) [Pd(NH3)2Br2] (square planar)\n(g) K3[Cu(Cl)5]\n(h) [Zn(NH3)2Cl2]\n"]], ["block_11", ["(a) [Pt(H2O)2Br2] (square planar)\n(b) [Pt(NH3)(py)(Cl)(Br)] (square planar, py = pyridine, C5H5N)\n(c) [Zn(NH3)3Cl](tetrahedral)\n(d) [Pt(NH3)3Cl](square planar)\n(e) [Ni(H2O)4Cl2]\n(f) [Co(C2O4)2Cl2](note that\nis the bidentate oxalate ion,\n"]], ["block_12", [" 19 \u2022 Exercises \n 975 \n"]]], "page_989": [["block_0", [" 976 \n 19 \u2022 Exercises \n"]], ["block_1", [" 30 . Draw diagrams for any cis, trans, and optical isomers that could exist for the following (en is\n"]], ["block_2", [" 31 . Name each of the compounds or ions given in Exercise 19.28, including the oxidation state of the metal.\n 32 . Name each of the compounds or ions given in Exercise 19.30.\n 33 . Specify whether the following complexes have isomers.\n"]], ["block_3", [" 34 . Predict whether the carbonate ligand\nwill coordinate to a metal center as a monodentate,\n"]], ["block_4", [" 35 . Draw the geometric, linkage, and ionization isomers for [CoCl5CN][CN].\n"]], ["block_5", [" 19.3 Spectroscopic and Magnetic Properties of Coordination Compounds \n"]], ["block_6", [" 36 . Determine the number of unpaired electrons expected for [Fe(NO2)6]and for [FeF6]in terms of crystal\n"]], ["block_7", [" 37 . Draw the crystal field diagrams for [Fe(NO2)6]and [FeF6]. State whether each complex is high spin or\n"]], ["block_8", [" 38 . Give the oxidation state of the metal, number of d electrons, and the number of unpaired electrons\n"]], ["block_9", [" 39 . The solid anhydrous solid CoCl2 is blue in color. Because it readily absorbs water from the air, it is used as\n"]], ["block_10", [" 40 . Is it possible for a complex of a metal in the transition series to have six unpaired electrons? Explain.\n 41 . How many unpaired electrons are present in each of the following?\n"]], ["block_11", [" 42 . Explain how the diphosphate ion, [O3P\u2212O\u2212PO3], can function as a water softener that prevents the\n"]], ["block_12", [" 43 . For complexes of the same metal ion with no change in oxidation number, the stability increases as the\n"]], ["block_13", [" 44 . Trimethylphosphine, P(CH3)3, can act as a ligand by donating the lone pair of electrons on the phosphorus\n"]], ["block_14", [" 45 . Would you expect the complex [Co(en)3]Cl3 to have any unpaired electrons? Any isomers?\n 46 . Would you expect the Mg3[Cr(CN)6]2 to be diamagnetic or paramagnetic? Explain your reasoning.\n 47 . Would you expect salts of the gold(I) ion, Au, to be colored? Explain.\n 48 . [CuCl4]is green. [Cu(H2O)6]is blue. Which absorbs higher-energy photons? Which is predicted to have\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["ethylenediamine):\n(a) [Co(en)2(NO2)Cl]\n"]], ["block_17", ["(b) [Co(en)2Cl2]\n"]], ["block_18", ["(c) [Pt(NH3)2Cl4]\n(d) [Cr(en)3]\n"]], ["block_19", ["(e) [Pt(NH3)2Cl2]\n"]], ["block_20", ["(a) tetrahedral [Ni(CO)2(Cl)2]\n(b) trigonal bipyramidal [Mn(CO)4NO]\n(c) [Pt(en)2Cl2]Cl2\n"]], ["block_21", ["bidentate, or tridentate ligand.\n"]], ["block_22", ["field theory.\n"]], ["block_23", ["low spin, paramagnetic or diamagnetic, and compare \u0394oct to P for each complex.\n"]], ["block_24", ["predicted for [Co(NH3)6]Cl3.\n"]], ["block_25", ["a humidity indicator to monitor if equipment (such as a cell phone) has been exposed to excessive levels of\nmoisture. Predict what product is formed by this reaction, and how many unpaired electrons this complex\nwill have.\n"]], ["block_26", ["(a) [CoF6](high spin)\n(b) [Mn(CN)6](low spin)\n(c) [Mn(CN)6](low spin)\n(d) [MnCl6](high spin)\n(e) [RhCl6](low spin)\n"]], ["block_27", ["precipitation of Feas an insoluble iron salt.\n"]], ["block_28", ["number of electrons in the t2g orbitals increases. Which complex in each of the following pairs of\ncomplexes is more stable?\n(a) [Fe(H2O)6]or [Fe(CN)6]\n"]], ["block_29", ["(b) [Co(NH3)6]or [CoF6]\n"]], ["block_30", ["(c) [Mn(CN)6]or [MnCl6]\n"]], ["block_31", ["atom. If trimethylphosphine is added to a solution of nickel(II) chloride in acetone, a blue compound that\nhas a molecular mass of approximately 270 g and contains 21.5% Ni, 26.0% Cl, and 52.5% P(CH3)3 can be\nisolated. This blue compound does not have any isomeric forms. What are the geometry and molecular\nformula of the blue compound?\n"]], ["block_32", ["a larger crystal field splitting?\n"]]], "page_990": [["block_0", ["compounds in living things has led to the epithet \u201ccarbon-based\u201d life. The truth is we know of no other kind of\nlife. Early chemists regarded substances isolated from organisms (plants and animals) as a different type of\nmatter that could not be synthesized artificially, and these substances were thus known as organic\ncompounds. The widespread belief called vitalism held that organic compounds were formed by a vital force\npresent only in living organisms. The German chemist Friedrich Wohler was one of the early chemists to refute\nthis aspect of vitalism, when, in 1828, he reported the synthesis of urea, a component of many body fluids,\nfrom nonliving materials. Since then, it has been recognized that organic molecules obey the same natural\nlaws as inorganic substances, and the category of organic compounds has evolved to include both natural and\nsynthetic compounds that contain carbon. Some carbon-containing compounds are not classified as organic,\nfor example, carbonates and cyanides, and simple oxides, such as CO and CO2. Although a single, precise\ndefinition has yet to be identified by the chemistry community, most agree that a defining trait of organic\nmolecules is the presence of carbon as the principal element, bonded to hydrogen and other carbon atoms.\n"]], ["block_1", ["CHAPTER 20\nOrganic Chemistry\n"]], ["block_2", [{"image_0": "990_0.png", "coords": [72, 104, 622, 233]}]], ["block_3", [" Figure 20.1 \nAll organic compounds contain carbon and most are formed by living things, although they are also\n"]], ["block_4", ["formed by geological and artificial processes. (credit left: modification of work by Jon Sullivan; credit left middle:\nmodification of work by Deb Tremper; credit right middle: modification of work by \u201cannszyp\u201d/Wikimedia Commons;\ncredit right: modification of work by George Shuklin)\n"]], ["block_5", [" CHAPTER OUTLINE \n"]], ["block_6", [" 20.1 Hydrocarbons \n 20.2 Alcohols and Ethers \n 20.3 Aldehydes, Ketones, Carboxylic Acids, and Esters \n 20.4 Amines and Amides \n"]], ["block_7", [" INTRODUCTION \n"]], ["block_8", ["Today, organic compounds are key components of plastics, soaps, perfumes, sweeteners, fabrics,\npharmaceuticals, and many other substances that we use every day. The value to us of organic compounds\nensures that organic chemistry is an important discipline within the general field of chemistry. In this chapter,\nwe discuss why the element carbon gives rise to a vast number and variety of compounds, how those\ncompounds are classified, and the role of organic compounds in representative biological and industrial\nsettings.\n"]], ["block_9", ["All living things on earth are formed mostly of carbon compounds. The prevalence of carbon\n"]]], "page_991": [["block_0", [" 978 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", [" 20.1 Hydrocarbons \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["The largest databaseof organic compounds lists about 10 million substances, which include compounds\noriginating from living organisms and those synthesized by chemists. The number of potential organic\ncompounds has been estimatedat 10\u2014an astronomically high number. The existence of so many organic\nmolecules is a consequence of the ability of carbon atoms to form up to four strong bonds to other carbon\natoms, resulting in chains and rings of many different sizes, shapes, and complexities.\n"]], ["block_4", ["The simplest organic compounds contain only the elements carbon and hydrogen, and are called\nhydrocarbons. Even though they are composed of only two types of atoms, there is a wide variety of\nhydrocarbons because they may consist of varying lengths of chains, branched chains, and rings of carbon\natoms, or combinations of these structures. In addition, hydrocarbons may differ in the types of carbon-carbon\nbonds present in their molecules. Many hydrocarbons are found in plants, animals, and their fossils; other\nhydrocarbons have been prepared in the laboratory. We use hydrocarbons every day, mainly as fuels, such as\nnatural gas, acetylene, propane, butane, and the principal components of gasoline, diesel fuel, and heating oil.\nThe familiar plastics polyethylene, polypropylene, and polystyrene are also hydrocarbons. We can distinguish\nseveral types of hydrocarbons by differences in the bonding between carbon atoms. This leads to differences\nin geometries and in the hybridization of the carbon orbitals.\n"]], ["block_5", [" Alkanes \n"]], ["block_6", [" Alkanes , or saturated hydrocarbons , contain only single covalent bonds between carbon atoms. Each of the\ncarbon atoms in an alkane has sphybrid orbitals and is bonded to four other atoms, each of which is either\ncarbon or hydrogen. The Lewis structures and models of methane, ethane, and pentane are illustrated in\nFigure 20.2. Carbon chains are usually drawn as straight lines in Lewis structures, but one has to remember\nthat Lewis structures are not intended to indicate the geometry of molecules. Notice that the carbon atoms in\nthe structural models (the ball-and-stick and space-filling models) of the pentane molecule do not lie in a\nstraight line. Because of the sphybridization, the bond angles in carbon chains are close to 109.5\u00b0, giving\nsuch chains in an alkane a zigzag shape.\n"]], ["block_7", ["The structures of alkanes and other organic molecules may also be represented in a less detailed manner by\ncondensed structural formulas (or simply, condensed formulas). Instead of the usual format for chemical\nformulas in which each element symbol appears just once, a condensed formula is written to suggest the\nbonding in the molecule. These formulas have the appearance of a Lewis structure from which most or all of\nthe bond symbols have been removed. Condensed structural formulas for ethane and pentane are shown at\nthe bottom of Figure 20.2, and several additional examples are provided in the exercises at the end of this\nchapter.\n"]], ["block_8", ["1 This is the Beilstein database, now available through the Reaxys site (www.elsevier.com/online-tools/reaxys).\n2 Peplow, Mark. \u201cOrganic Synthesis: The Robo-Chemist,\u201d Nature 512 (2014): 20\u20132.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["\u2022\nExplain the importance of hydrocarbons and the reason for their diversity\n"]], ["block_11", ["\u2022\nName saturated and unsaturated hydrocarbons, and molecules derived from them\n"]], ["block_12", ["\u2022\nDescribe the reactions characteristic of saturated and unsaturated hydrocarbons\n"]], ["block_13", ["\u2022\nIdentify structural and geometric isomers of hydrocarbons\n"]]], "page_992": [["block_0", [{"image_0": "992_0.png", "coords": [72, 57, 540, 275]}]], ["block_1", [" FIGURE 20.2 \nPictured are the Lewis structures, ball-and-stick models, and space-filling models for molecules of\n"]], ["block_2", ["methane, ethane, and pentane.\n"]], ["block_3", ["A common method used by organic chemists to simplify the drawings of larger molecules is to use a skeletal \n structure (also called a line-angle structure). In this type of structure, carbon atoms are not symbolized with a\nC, but represented by each end of a line or bend in a line. Hydrogen atoms are not drawn if they are attached to\na carbon. Other atoms besides carbon and hydrogen are represented by their elemental symbols. Figure 20.3\nshows three different ways to draw the same structure.\n"]], ["block_4", [{"image_1": "992_1.png", "coords": [72, 378, 540, 559]}]], ["block_5", [" FIGURE 20.3 \nThe same structure can be represented three different ways: an expanded formula, a condensed\n"]], ["block_6", ["formula, and a skeletal structure.\n"]], ["block_7", [" Drawing Skeletal Structures \n"]], ["block_8", ["Draw the skeletal structures for these two molecules:\n"]], ["block_9", ["EXAMPLE 20.1\n"]], ["block_10", [" 20.1 \u2022 Hydrocarbons \n 979 \n"]]], "page_993": [["block_0", [" 980 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", [{"image_0": "993_0.png", "coords": [72, 57, 306, 128]}]], ["block_2", [" Solution \n"]], ["block_3", ["Each carbon atom is converted into the end of a line or the place where lines intersect. All hydrogen atoms\nattached to the carbon atoms are left out of the structure (although we still need to recognize they are there):\n"]], ["block_4", [{"image_1": "993_1.png", "coords": [72, 178, 306, 243]}]], ["block_5", [" Check Your Learning \n"]], ["block_6", ["Draw the skeletal structures for these two molecules:\n"]], ["block_7", [{"image_2": "993_2.png", "coords": [72, 280, 306, 368]}]], ["block_8", [" Answer: \n"]], ["block_9", [{"image_3": "993_3.png", "coords": [72, 398, 306, 469]}]], ["block_10", [" Interpreting Skeletal Structures \n"]], ["block_11", ["Identify the chemical formula of the molecule represented here:\n"]], ["block_12", [{"image_4": "993_4.png", "coords": [72, 554, 189, 595]}]], ["block_13", [" Solution \n"]], ["block_14", ["There are eight places where lines intersect or end, meaning that there are eight carbon atoms in the molecule.\nSince we know that carbon atoms tend to make four bonds, each carbon atom will have the number of\nhydrogen atoms that are required for four bonds. This compound contains 16 hydrogen atoms for a molecular\nformula of C8H16.\n"]], ["block_15", ["Location of the hydrogen atoms:\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["EXAMPLE 20.2\n"]]], "page_994": [["block_0", [{"image_0": "994_0.png", "coords": [72, 57, 306, 119]}]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["Identify the chemical formula of the molecule represented here:\n"]], ["block_3", [{"image_1": "994_1.png", "coords": [72, 156, 189, 202]}]], ["block_4", [" Answer: \nC9H20\n"]], ["block_5", ["All alkanes are composed of carbon and hydrogen atoms, and have similar bonds, structures, and formulas;\nnoncyclic alkanes all have a formula of CnH2n+2. The number of carbon atoms present in an alkane has no\nlimit. Greater numbers of atoms in the molecules will lead to stronger intermolecular attractions (dispersion\nforces) and correspondingly different physical properties of the molecules. Properties such as melting point\nand boiling point (Table 20.1) usually change smoothly and predictably as the number of carbon and hydrogen\natoms in the molecules change.\n"]], ["block_6", ["3 Physical properties for C4H10 and heavier molecules are those of the normal isomer, n-butane, n-pentane, etc.\n"]], ["block_7", [" Alkane \n Molecular \n Formula \n"]], ["block_8", ["methane\nCH4\n\u2013182.5\n\u2013161.5\ngas\n1\n"]], ["block_9", ["ethane\nC2H6\n\u2013183.3\n\u201388.6\ngas\n1\n"]], ["block_10", ["propane\nC3H8\n\u2013187.7\n\u201342.1\ngas\n1\n"]], ["block_11", ["butane\nC4H10\n\u2013138.3\n\u20130.5\ngas\n2\n"]], ["block_12", ["pentane\nC5H12\n\u2013129.7\n36.1\nliquid\n3\n"]], ["block_13", ["hexane\nC6H14\n\u201395.3\n68.7\nliquid\n5\n"]], ["block_14", ["heptane\nC7H16\n\u201390.6\n98.4\nliquid\n9\n"]], ["block_15", ["octane\nC8H18\n\u201356.8\n125.7\nliquid\n18\n"]], ["block_16", ["nonane\nC9H20\n\u201353.6\n150.8\nliquid\n35\n"]], ["block_17", ["decane\nC10H22\n\u201329.7\n174.0\nliquid\n75\n"]], ["block_18", ["tetradecane\nC14H30\n5.9\n253.5\nsolid\n1858\n"]], ["block_19", ["octadecane\nC18H38\n28.2\n316.1\nsolid\n60,523\n"]], ["block_20", [" Melting Point \n (\u00b0C) \n"]], ["block_21", ["Properties of Some Alkanes\n"]], ["block_22", [" Boiling Point \n (\u00b0C) \n"]], ["block_23", [" Phase at \n STP 4 \n"]], ["block_24", [" Number of Structural \n Isomers \n"]], ["block_25", [" 20.1 \u2022 Hydrocarbons \n 981 \n"]]], "page_995": [["block_0", [" 982 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", ["Hydrocarbons with the same formula, including alkanes, can have different structures. For example, two\nalkanes have the formula C4H10: They are called n-butane and 2-methylpropane (or isobutane), and have the\nfollowing Lewis structures:\n"]], ["block_2", [{"image_0": "995_0.png", "coords": [72, 101, 423, 376]}]], ["block_3", ["The compounds n-butane and 2-methylpropane are structural isomers (the term constitutional isomers is also\ncommonly used). Constitutional isomers have the same molecular formula but different spatial arrangements\nof the atoms in their molecules. The n-butane molecule contains an unbranched chain, meaning that no\ncarbon atom is bonded to more than two other carbon atoms. We use the term normal, or the prefix n, to refer\nto a chain of carbon atoms without branching. The compound 2\u2013methylpropane has a branched chain (the\ncarbon atom in the center of the Lewis structure is bonded to three other carbon atoms)\n"]], ["block_4", ["Identifying isomers from Lewis structures is not as easy as it looks. Lewis structures that look different may\nactually represent the same isomers. For example, the three structures in Figure 20.4 all represent the same\nmolecule, n-butane, and hence are not different isomers. They are identical because each contains an\nunbranched chain of four carbon atoms.\n"]], ["block_5", ["4 STP indicates a temperature of 0 \u00b0C and a pressure of 1 atm.\n"]], ["block_6", [" Access for free at openstax.org \n"]]], "page_996": [["block_0", [" FIGURE 20.4 \nThese three representations of the structure of n-butane are not isomers because they all contain\n"]], ["block_1", ["the same arrangement of atoms and bonds.\n"]], ["block_2", [" The Basics of Organic Nomenclature: Naming Alkanes \n"]], ["block_3", ["The International Union of Pure and Applied Chemistry (IUPAC) has devised a system of nomenclature that\nbegins with the names of the alkanes and can be adjusted from there to account for more complicated\nstructures. The nomenclature for alkanes is based on two rules:\n"]], ["block_4", [{"image_0": "996_0.png", "coords": [72, 542, 540, 607]}]], ["block_5", ["When more than one substituent is present, either on the same carbon atom or on different carbon atoms, the\nsubstituents are listed alphabetically. Because the carbon atom numbering begins at the end closest to a\nsubstituent, the longest chain of carbon atoms is numbered in such a way as to produce the lowest number for\nthe substituents. The ending -o replaces -ide at the end of the name of an electronegative substituent (in ionic\ncompounds, the negatively charged ion ends with -ide like chloride; in organic compounds, such atoms are\ntreated as substituents and the -o ending is used). The number of substituents of the same type is indicated by\nthe prefixes di- (two), tri- (three), tetra- (four), and so on (for example, difluoro- indicates two fluoride\nsubstituents).\n"]], ["block_6", ["1.\nTo name an alkane, first identify the longest chain of carbon atoms in its structure. A two-carbon chain is\ncalled ethane; a three-carbon chain, propane; and a four-carbon chain, butane. Longer chains are named\nas follows: pentane (five-carbon chain), hexane (6), heptane (7), octane (8), nonane (9), and decane (10).\nThese prefixes can be seen in the names of the alkanes described in Table 20.1.\n"]], ["block_7", ["2.\nAdd prefixes to the name of the longest chain to indicate the positions and names of substituents .\nSubstituents are branches or functional groups that replace hydrogen atoms on a chain. The position of a\nsubstituent or branch is identified by the number of the carbon atom it is bonded to in the chain. We\nnumber the carbon atoms in the chain by counting from the end of the chain nearest the substituents.\nMultiple substituents are named individually and placed in alphabetical order at the front of the name.\n"]], ["block_8", [{"image_1": "996_1.png", "coords": [130, 57, 481, 324]}]], ["block_9", [" 20.1 \u2022 Hydrocarbons \n 983 \n"]]], "page_997": [["block_0", [" 984 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", [" Naming Halogen-substituted Alkanes \n"]], ["block_2", ["Name the molecule whose structure is shown here:\n"]], ["block_3", [{"image_0": "997_0.png", "coords": [72, 125, 189, 175]}]], ["block_4", [" Solution \n"]], ["block_5", [{"image_1": "997_1.png", "coords": [72, 198, 189, 250]}]], ["block_6", ["The four-carbon chain is numbered from the end with the chlorine atom. This puts the substituents on\npositions 1 and 2 (numbering from the other end would put the substituents on positions 3 and 4). Four carbon\natoms means that the base name of this compound will be butane. The bromine at position 2 will be described\nby adding 2-bromo-; this will come at the beginning of the name, since bromo- comes before chloro-\nalphabetically. The chlorine at position 1 will be described by adding 1-chloro-, resulting in the name of the\nmolecule being 2-bromo-1-chlorobutane.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["Name the following molecule:\n"]], ["block_9", [{"image_2": "997_2.png", "coords": [72, 369, 306, 419]}]], ["block_10", [" Answer: \n3,3-dibromo-2-iodopentane\n"]], ["block_11", ["We call a substituent that contains one less hydrogen than the corresponding alkane an alkyl group. The name\nof an alkyl group is obtained by dropping the suffix -ane of the alkane name and adding -yl:\n"]], ["block_12", [{"image_3": "997_3.png", "coords": [72, 502, 423, 574]}]], ["block_13", ["The open bonds in the methyl and ethyl groups indicate that these alkyl groups are bonded to another atom.\n"]], ["block_14", [" Naming Substituted Alkanes \n"]], ["block_15", ["Name the molecule whose structure is shown here:\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["EXAMPLE 20.3\n"]], ["block_18", ["EXAMPLE 20.4\n"]]], "page_998": [["block_0", ["The longest carbon chain runs horizontally across the page and contains six carbon atoms (this makes the\nbase of the name hexane, but we will also need to incorporate the name of the branch). In this case, we want to\nnumber from right to left (as shown by the blue numbers) so the branch is connected to carbon 3 (imagine the\nnumbers from left to right\u2014this would put the branch on carbon 4, violating our rules). The branch attached to\nposition 3 of our chain contains two carbon atoms (numbered in red)\u2014so we take our name for two carbons\neth- and attach -yl at the end to signify we are describing a branch. Putting all the pieces together, this\nmolecule is 3-ethylhexane.\n"]], ["block_1", [{"image_0": "998_0.png", "coords": [72, 57, 306, 178]}]], ["block_2", [" Solution \n"]], ["block_3", [" Check Your Learning \n"]], ["block_4", ["Name the following molecule:\n"]], ["block_5", [{"image_1": "998_1.png", "coords": [72, 325, 306, 446]}]], ["block_6", [" Answer: \n4-propyloctane\n"]], ["block_7", ["Some hydrocarbons can form more than one type of alkyl group when the hydrogen atoms that would be\nremoved have different \u201cenvironments\u201d in the molecule. This diversity of possible alkyl groups can be\nidentified in the following way: The four hydrogen atoms in a methane molecule are equivalent; they all have\nthe same environment. They are equivalent because each is bonded to a carbon atom (the same carbon atom)\nthat is bonded to three hydrogen atoms. (It may be easier to see the equivalency in the ball and stick models in\nFigure 20.2. Removal of any one of the four hydrogen atoms from methane forms a methyl group. Likewise, the\nsix hydrogen atoms in ethane are equivalent (Figure 20.2) and removing any one of these hydrogen atoms\nproduces an ethyl group. Each of the six hydrogen atoms is bonded to a carbon atom that is bonded to two\nother hydrogen atoms and a carbon atom. However, in both propane and 2\u2013methylpropane, there are\nhydrogen atoms in two different environments, distinguished by the adjacent atoms or groups of atoms:\n"]], ["block_8", [" 20.1 \u2022 Hydrocarbons \n 985 \n"]]], "page_999": [["block_0", [" 986 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", [{"image_0": "999_0.png", "coords": [72, 57, 306, 172]}]], ["block_2", ["Each of the six equivalent hydrogen atoms of the first type in propane and each of the nine equivalent\nhydrogen atoms of that type in 2-methylpropane (all shown in black) are bonded to a carbon atom that is\nbonded to only one other carbon atom. The two purple hydrogen atoms in propane are of a second type. They\ndiffer from the six hydrogen atoms of the first type in that they are bonded to a carbon atom bonded to two\nother carbon atoms. The green hydrogen atom in 2-methylpropane differs from the other nine hydrogen atoms\nin that molecule and from the purple hydrogen atoms in propane. The green hydrogen atom in\n2-methylpropane is bonded to a carbon atom bonded to three other carbon atoms. Two different alkyl groups\ncan be formed from each of these molecules, depending on which hydrogen atom is removed. The names and\nstructures of these and several other alkyl groups are listed in Figure 20.5.\n"]], ["block_3", [" FIGURE 20.5 \nThis listing gives the names and formulas for various alkyl groups formed by the removal of hydrogen\n"]], ["block_4", ["atoms from different locations.\n"]], ["block_5", ["Note that alkyl groups do not exist as stable independent entities. They are always a part of some larger\nmolecule. The location of an alkyl group on a hydrocarbon chain is indicated in the same way as any other\nsubstituent:\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [{"image_1": "999_1.png", "coords": [189, 295, 423, 573]}]]], "page_1000": [["block_0", [{"image_0": "1000_0.png", "coords": [72, 57, 540, 148]}]], ["block_1", ["Alkanes are relatively stable molecules, but heat or light will activate reactions that involve the breaking of C\u2013H\nor C\u2013C single bonds. Combustion is one such reaction:\n"]], ["block_2", ["Alkanes burn in the presence of oxygen, a highly exothermic oxidation-reduction reaction that produces\ncarbon dioxide and water. As a consequence, alkanes are excellent fuels. For example, methane, CH4, is the\nprincipal component of natural gas. Butane, C4H10, used in camping stoves and lighters is an alkane. Gasoline\nis a liquid mixture of continuous- and branched-chain alkanes, each containing from five to nine carbon\natoms, plus various additives to improve its performance as a fuel. Kerosene, diesel oil, and fuel oil are\nprimarily mixtures of alkanes with higher molecular masses. The main source of these liquid alkane fuels is\ncrude oil, a complex mixture that is separated by fractional distillation. Fractional distillation takes advantage\nof differences in the boiling points of the components of the mixture (see Figure 20.6). You may recall that\nboiling point is a function of intermolecular interactions, which was discussed in the chapter on solutions and\ncolloids.\n"]], ["block_3", [{"image_1": "1000_1.png", "coords": [72, 332, 540, 646]}]], ["block_4", [" FIGURE 20.6 \nIn a column for the fractional distillation of crude oil, oil heated to about 425 \u00b0C in the furnace\n"]], ["block_5", ["vaporizes when it enters the base of the tower. The vapors rise through bubble caps in a series of trays in the tower.\nAs the vapors gradually cool, fractions of higher, then of lower, boiling points condense to liquids and are drawn off.\n(credit left: modification of work by Luigi Chiesa)\n"]], ["block_6", ["In a substitution reaction , another typical reaction of alkanes, one or more of the alkane\u2019s hydrogen atoms is\nreplaced with a different atom or group of atoms. No carbon-carbon bonds are broken in these reactions, and\n"]], ["block_7", [" 20.1 \u2022 Hydrocarbons \n 987 \n"]]], "page_1001": [["block_0", [" 988 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", ["the hybridization of the carbon atoms does not change. For example, the reaction between ethane and\nmolecular chlorine depicted here is a substitution reaction:\n"]], ["block_2", [{"image_0": "1001_0.png", "coords": [72, 89, 423, 162]}]], ["block_3", ["The C\u2013Cl portion of the chloroethane molecule is an example of a functional group , the part or moiety of a\nmolecule that imparts a specific chemical reactivity. The types of functional groups present in an organic\nmolecule are major determinants of its chemical properties and are used as a means of classifying organic\ncompounds as detailed in the remaining sections of this chapter.\n"]], ["block_4", ["Want more practice naming alkanes? Watch this brief video tutorial (http://openstax.org/l/16alkanes) to review\nthe nomenclature process.\n"]], ["block_5", [" Alkenes \n"]], ["block_6", ["Organic compounds that contain one or more double or triple bonds between carbon atoms are described as\nunsaturated. You have likely heard of unsaturated fats. These are complex organic molecules with long chains\nof carbon atoms, which contain at least one double bond between carbon atoms. Unsaturated hydrocarbon\nmolecules that contain one or more double bonds are called alkenes . Carbon atoms linked by a double bond\nare bound together by two bonds, one \u03c3 bond and one \u03c0 bond. Double and triple bonds give rise to a different\ngeometry around the carbon atom that participates in them, leading to important differences in molecular\nshape and properties. The differing geometries are responsible for the different properties of unsaturated\nversus saturated fats.\n"]], ["block_7", ["Ethene, C2H4, is the simplest alkene. Each carbon atom in ethene, commonly called ethylene, has a trigonal\nplanar structure. The second member of the series is propene (propylene) (Figure 20.7); the butene isomers\nfollow in the series. Four carbon atoms in the chain of butene allows for the formation of isomers based on the\nposition of the double bond, as well as a new form of isomerism.\n"]], ["block_8", [{"image_1": "1001_1.png", "coords": [72, 471, 540, 692]}]], ["block_9", [" FIGURE 20.7 \nExpanded structures, ball-and-stick structures, and space-filling models for the alkenes ethene,\n"]], ["block_10", ["propene, and 1-butene are shown.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["LINK TO LEARNING\n"]]], "page_1002": [["block_0", ["Ethylene (the common industrial name for ethene) is a basic raw material in the production of polyethylene\nand other important compounds. Over 135 million tons of ethylene were produced worldwide in 2010 for use\nin the polymer, petrochemical, and plastic industries. Ethylene is produced industrially in a process called\ncracking, in which the long hydrocarbon chains in a petroleum mixture are broken into smaller molecules.\n"]], ["block_1", ["Chemistry in Everyday Life\n"]], ["block_2", [" Recycling Plastics \nPolymers (from Greek words poly meaning \u201cmany\u201d and mer meaning \u201cparts\u201d) are large molecules made up\nof repeating units, referred to as monomers. Polymers can be natural (starch is a polymer of sugar residues\nand proteins are polymers of amino acids) or synthetic [like polyethylene, polyvinyl chloride (PVC), and\npolystyrene]. The variety of structures of polymers translates into a broad range of properties and uses that\nmake them integral parts of our everyday lives. Adding functional groups to the structure of a polymer can\nresult in significantly different properties (see the discussion about Kevlar later in this chapter).\n"]], ["block_3", ["An example of a polymerization reaction is shown in Figure 20.8. The monomer ethylene (C2H4) is a gas at\nroom temperature, but when polymerized, using a transition metal catalyst, it is transformed into a solid\nmaterial made up of long chains of \u2013CH2\u2013 units called polyethylene. Polyethylene is a commodity plastic\nused primarily for packaging (bags and films).\n"]], ["block_4", ["Polyethylene is a member of one subset of synthetic polymers classified as plastics. Plastics are synthetic\norganic solids that can be molded; they are typically organic polymers with high molecular masses. Most of\nthe monomers that go into common plastics (ethylene, propylene, vinyl chloride, styrene, and ethylene\nterephthalate) are derived from petrochemicals and are not very biodegradable, making them candidate\nmaterials for recycling. Recycling plastics helps minimize the need for using more of the petrochemical\nsupplies and also minimizes the environmental damage caused by throwing away these nonbiodegradable\nmaterials.\n"]], ["block_5", ["Plastic recycling is the process of recovering waste, scrap, or used plastics, and reprocessing the material\ninto useful products. For example, polyethylene terephthalate (soft drink bottles) can be melted down and\nused for plastic furniture, in carpets, or for other applications. Other plastics, like polyethylene (bags) and\npolypropylene (cups, plastic food containers), can be recycled or reprocessed to be used again. Many areas\nof the country have recycling programs that focus on one or more of the commodity plastics that have been\nassigned a recycling code (see Figure 20.9). These operations have been in effect since the 1970s and have\nmade the production of some plastics among the most efficient industrial operations today.\n"]], ["block_6", [{"image_0": "1002_0.png", "coords": [90, 294, 522, 457]}]], ["block_7", [" FIGURE 20.8 \nThe reaction for the polymerization of ethylene to polyethylene is shown.\n"]], ["block_8", [" 20.1 \u2022 Hydrocarbons \n 989 \n"]]], "page_1003": [["block_0", [" 990 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", ["The name of an alkene is derived from the name of the alkane with the same number of carbon atoms. The\npresence of the double bond is signified by replacing the suffix -ane with the suffix -ene. The location of the\ndouble bond is identified by naming the smaller of the numbers of the carbon atoms participating in the\ndouble bond:\n"]], ["block_2", [{"image_0": "1003_0.png", "coords": [72, 509, 540, 595]}]], ["block_3", [" Isomers of Alkenes \nMolecules of 1-butene and 2-butene are structural isomers; the arrangement of the atoms in these two\nmolecules differs. As an example of arrangement differences, the first carbon atom in 1-butene is bonded to\ntwo hydrogen atoms; the first carbon atom in 2-butene is bonded to three hydrogen atoms.\n"]], ["block_4", ["The compound 2-butene and some other alkenes also form a second type of isomer called a geometric isomer.\nIn a set of geometric isomers, the same types of atoms are attached to each other in the same order, but the\ngeometries of the two molecules differ. Geometric isomers of alkenes differ in the orientation of the groups on\neither side of a\nbond.\n"]], ["block_5", ["Carbon atoms are free to rotate around a single bond but not around a double bond; a double bond is rigid.\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [{"image_1": "1003_1.png", "coords": [90, 57, 522, 410]}]], ["block_8", [" FIGURE 20.9 \nEach type of recyclable plastic is imprinted with a code for easy identification.\n"]]], "page_1004": [["block_0", ["bond, being a weaker bond, is disrupted much more easily than a \u03c3 bond. Thus, alkenes undergo a\ncharacteristic reaction in which the \u03c0 bond is broken and replaced by two \u03c3 bonds. This reaction is called an\n addition reaction . The hybridization of the carbon atoms in the double bond in an alkene changes from spto\nspduring an addition reaction. For example, halogens add to the double bond in an alkene instead of\nreplacing hydrogen, as occurs in an alkane:\n"]], ["block_1", ["This makes it possible to have two isomers of 2-butene, one with both methyl groups on the same side of the\ndouble bond and one with the methyl groups on opposite sides. When structures of butene are drawn with\n120\u00b0 bond angles around the sp-hybridized carbon atoms participating in the double bond, the isomers are\napparent. The 2-butene isomer in which the two methyl groups are on the same side is called a cis-isomer; the\none in which the two methyl groups are on opposite sides is called a trans-isomer (Figure 20.10). The different\ngeometries produce different physical properties, such as boiling point, that may make separation of the\nisomers possible:\n"]], ["block_2", [{"image_0": "1004_0.png", "coords": [72, 152, 540, 392]}]], ["block_3", ["Alkenes are much more reactive than alkanes because the\nmoiety is a reactive functional group. A \u03c0\n"]], ["block_4", [{"image_1": "1004_1.png", "coords": [72, 495, 423, 569]}]], ["block_5", [" Alkene Reactivity and Naming \n"]], ["block_6", ["Provide the IUPAC names for the reactant and product of the halogenation reaction shown here:\n"]], ["block_7", [{"image_2": "1004_2.png", "coords": [72, 639, 306, 685]}]], ["block_8", [" Solution \n"]], ["block_9", ["The reactant is a five-carbon chain that contains a carbon-carbon double bond, so the base name will be\n"]], ["block_10", ["EXAMPLE 20.5\n"]], ["block_11", [" FIGURE 20.10 \nThese molecular models show the structural and geometric isomers of butene.\n"]], ["block_12", [" 20.1 \u2022 Hydrocarbons \n 991 \n"]]], "page_1005": [["block_0", [" 992 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", ["pentene. We begin counting at the end of the chain closest to the double bond\u2014in this case, from the left\u2014the\ndouble bond spans carbons 2 and 3, so the name becomes 2-pentene. Since there are two carbon-containing\ngroups attached to the two carbon atoms in the double bond\u2014and they are on the same side of the double\nbond\u2014this molecule is the cis-isomer, making the name of the starting alkene cis-2-pentene. The product of\nthe halogenation reaction will have two chlorine atoms attached to the carbon atoms that were a part of the\ncarbon-carbon double bond:\n"]], ["block_2", [{"image_0": "1005_0.png", "coords": [72, 139, 189, 186]}]], ["block_3", ["This molecule is now a substituted alkane and will be named as such. The base of the name will be pentane.\nWe will count from the end that numbers the carbon atoms where the chlorine atoms are attached as 2 and 3,\nmaking the name of the product 2,3-dichloropentane.\n"]], ["block_4", [" Check Your Learning \n"]], ["block_5", ["Provide names for the reactant and product of the reaction shown:\n"]], ["block_6", [{"image_1": "1005_1.png", "coords": [72, 267, 423, 319]}]], ["block_7", [" Answer: \nreactant: cis-3-hexene product: 3,4-dichlorohexane\n"]], ["block_8", [" Alkynes \n"]], ["block_9", ["Hydrocarbon molecules with one or more triple bonds are called alkynes ; they make up another series of\nunsaturated hydrocarbons. Two carbon atoms joined by a triple bond are bound together by one \u03c3 bond and\ntwo \u03c0 bonds. The sp-hybridized carbons involved in the triple bond have bond angles of 180\u00b0, giving these\ntypes of bonds a linear, rod-like shape.\n"]], ["block_10", ["The simplest member of the alkyne series is ethyne, C2H2, commonly called acetylene. The Lewis structure for\nethyne, a linear molecule, is:\n"]], ["block_11", [{"image_2": "1005_2.png", "coords": [72, 478, 189, 509]}]], ["block_12", ["The IUPAC nomenclature for alkynes is similar to that for alkenes except that the suffix -yne is used to indicate\na triple bond in the chain. For example,\nis called 1-butyne.\n"]], ["block_13", [" Structure of Alkynes \n"]], ["block_14", ["Describe the geometry and hybridization of the carbon atoms in the following molecule:\n"]], ["block_15", [{"image_3": "1005_3.png", "coords": [72, 611, 164, 632]}]], ["block_16", [" Solution \n"]], ["block_17", ["Carbon atoms 1 and 4 have four single bonds and are thus tetrahedral with sphybridization. Carbon atoms 2\nand 3 are involved in the triple bond, so they have linear geometries and would be classified as sp hybrids.\n"]], ["block_18", [" Check Your Learning \n"]], ["block_19", ["Identify the hybridization and bond angles at the carbon atoms in the molecule shown:\n"]], ["block_20", [" Access for free at openstax.org \n"]], ["block_21", ["EXAMPLE 20.6\n"]]], "page_1006": [["block_0", [{"image_0": "1006_0.png", "coords": [72, 57, 306, 105]}]], ["block_1", [" Answer: \ncarbon 1: sp, 180\u00b0; carbon 2: sp, 180\u00b0; carbon 3: sp, 120\u00b0; carbon 4: sp, 120\u00b0; carbon 5: sp, 109.5\u00b0\n"]], ["block_2", ["Chemically, the alkynes are similar to the alkenes. Since the\nfunctional group has two \u03c0 bonds, alkynes\n"]], ["block_3", ["typically react even more readily, and react with twice as much reagent in addition reactions. The reaction of\nacetylene with bromine is a typical example:\n"]], ["block_4", [{"image_1": "1006_1.png", "coords": [72, 200, 540, 282]}]], ["block_5", ["Acetylene and the other alkynes also burn readily. An acetylene torch takes advantage of the high heat of\ncombustion for acetylene.\n"]], ["block_6", [" Aromatic Hydrocarbons \n"]], ["block_7", ["Benzene, C6H6, is the simplest member of a large family of hydrocarbons, called aromatic hydrocarbons .\nThese compounds contain ring structures and exhibit bonding that must be described using the resonance\nhybrid concept of valence bond theory or the delocalization concept of molecular orbital theory. (To review\nthese concepts, refer to the earlier chapters on chemical bonding). The resonance structures for benzene,\nC6H6, are:\n"]], ["block_8", [{"image_2": "1006_2.png", "coords": [72, 405, 306, 487]}]], ["block_9", ["Valence bond theory describes the benzene molecule and other planar aromatic hydrocarbon molecules as\nhexagonal rings of sp-hybridized carbon atoms with the unhybridized p orbital of each carbon atom\nperpendicular to the plane of the ring. Three valence electrons in the sphybrid orbitals of each carbon atom\nand the valence electron of each hydrogen atom form the framework of \u03c3 bonds in the benzene molecule. The\nfourth valence electron of each carbon atom is shared with an adjacent carbon atom in their unhybridized p\norbitals to yield the \u03c0 bonds. Benzene does not, however, exhibit the characteristics typical of an alkene. Each\nof the six bonds between its carbon atoms is equivalent and exhibits properties that are intermediate between\nthose of a C\u2013C single bond and a\ndouble bond. To represent this unique bonding, structural formulas for\n"]], ["block_10", ["benzene and its derivatives are typically drawn with single bonds between the carbon atoms and a circle\nwithin the ring as shown in Figure 20.11.\n"]], ["block_11", ["There are many derivatives of benzene. The hydrogen atoms can be replaced by many different substituents.\nAromatic compounds more readily undergo substitution reactions than addition reactions; replacement of one\n"]], ["block_12", [" FIGURE 20.11 \nThis condensed formula shows the unique bonding structure of benzene.\n"]], ["block_13", [{"image_3": "1006_3.png", "coords": [247, 622, 364, 683]}]], ["block_14", [" 20.1 \u2022 Hydrocarbons \n 993 \n"]]], "page_1007": [["block_0", [" 994 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", ["of the hydrogen atoms with another substituent will leave the delocalized double bonds intact. The following\nare typical examples of substituted benzene derivatives:\n"]], ["block_2", [{"image_0": "1007_0.png", "coords": [72, 89, 423, 174]}]], ["block_3", ["Toluene and xylene are important solvents and raw materials in the chemical industry. Styrene is used to\nproduce the polymer polystyrene.\n"]], ["block_4", [" Structure of Aromatic Hydrocarbons \n"]], ["block_5", ["One possible isomer created by a substitution reaction that replaces a hydrogen atom attached to the aromatic\nring of toluene with a chlorine atom is shown here. Draw two other possible isomers in which the chlorine\natom replaces a different hydrogen atom attached to the aromatic ring:\n"]], ["block_6", [{"image_1": "1007_1.png", "coords": [72, 301, 306, 384]}]], ["block_7", [" Solution \n"]], ["block_8", ["Since the six-carbon ring with alternating double bonds is necessary for the molecule to be classified as\naromatic, appropriate isomers can be produced only by changing the positions of the chloro-substituent\nrelative to the methyl-substituent:\n"]], ["block_9", [{"image_2": "1007_2.png", "coords": [72, 447, 504, 512]}]], ["block_10", [" Check Your Learning \n"]], ["block_11", ["Draw three isomers of a six-membered aromatic ring compound substituted with two bromines.\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["EXAMPLE 20.7\n"]]], "page_1008": [["block_0", [" Answer: \n"]], ["block_1", [{"image_0": "1008_0.png", "coords": [72, 72, 423, 253]}]], ["block_2", [" 20.2 Alcohols and Ethers \n"]], ["block_3", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_4", ["In this section, we will learn about alcohols and ethers.\n"]], ["block_5", [" Alcohols \n"]], ["block_6", ["Incorporation of an oxygen atom into carbon- and hydrogen-containing molecules leads to new functional\ngroups and new families of compounds. When the oxygen atom is attached by single bonds, the molecule is\neither an alcohol or ether.\n"]], ["block_7", [" Alcohols are derivatives of hydrocarbons in which an \u2013OH group has replaced a hydrogen atom. Although all\nalcohols have one or more hydroxyl (\u2013OH) functional groups, they do not behave like bases such as NaOH and\nKOH. NaOH and KOH are ionic compounds that contain OHions. Alcohols are covalent molecules; the \u2013OH\ngroup in an alcohol molecule is attached to a carbon atom by a covalent bond.\n"]], ["block_8", ["Ethanol, CH3CH2OH, also called ethyl alcohol, is a particularly important alcohol for human use. Ethanol is the\nalcohol produced by some species of yeast that is found in wine, beer, and distilled drinks. It has long been\nprepared by humans harnessing the metabolic efforts of yeasts in fermenting various sugars:\n"]], ["block_9", [{"image_1": "1008_1.png", "coords": [72, 548, 306, 584]}]], ["block_10", ["Large quantities of ethanol are synthesized from the addition reaction of water with ethylene using an acid as a\ncatalyst:\n"]], ["block_11", [{"image_2": "1008_2.png", "coords": [72, 618, 306, 670]}]], ["block_12", ["Alcohols containing two or more hydroxyl groups can be made. Examples include 1,2-ethanediol (ethylene\nglycol, used in antifreeze) and 1,2,3-propanetriol (glycerine, used as a solvent for cosmetics and medicines):\n"]], ["block_13", ["\u2022\nDescribe the structure and properties of alcohols\n"]], ["block_14", ["\u2022\nDescribe the structure and properties of ethers\n"]], ["block_15", ["\u2022\nName and draw structures for alcohols and ethers\n"]], ["block_16", [" 20.2 \u2022 Alcohols and Ethers \n 995 \n"]]], "page_1009": [["block_0", [" 996 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", ["The carbon chain contains five carbon atoms. If the hydroxyl group was not present, we would have named this\nmolecule pentane. To address the fact that the hydroxyl group is present, we change the ending of the name to\n-ol. In this case, since the \u2013OH is attached to carbon 2 in the chain, we would name this molecule 2-pentanol.\n"]], ["block_2", [{"image_0": "1009_0.png", "coords": [72, 57, 306, 167]}]], ["block_3", [" Naming Alcohols \nThe name of an alcohol comes from the hydrocarbon from which it was derived. The final -e in the name of the\nhydrocarbon is replaced by -ol, and the carbon atom to which the \u2013OH group is bonded is indicated by a\nnumber placed before the name.\n"]], ["block_4", [" Naming Alcohols \n"]], ["block_5", ["Consider the following example. How should it be named?\n"]], ["block_6", [{"image_1": "1009_1.png", "coords": [72, 295, 306, 367]}]], ["block_7", [" Solution \n"]], ["block_8", [" Check Your Learning \n"]], ["block_9", ["Name the following molecule:\n"]], ["block_10", [{"image_2": "1009_2.png", "coords": [72, 464, 189, 504]}]], ["block_11", [" Answer: \n2-methyl-2-pentanol\n"]], ["block_12", [" Ethers \n"]], ["block_13", [" Ethers are compounds that contain the functional group \u2013O\u2013. Ethers do not have a designated suffix like the\nother types of molecules we have named so far. In the IUPAC system, the oxygen atom and the smaller carbon\nbranch are named as an alkoxy substituent and the remainder of the molecule as the base chain, as in alkanes.\nAs shown in the following compound, the red symbols represent the smaller alkyl group and the oxygen atom,\nwhich would be named \u201cmethoxy.\u201d The larger carbon branch would be ethane, making the molecule\nmethoxyethane. Many ethers are referred to with common names instead of the IUPAC system names. For\ncommon names, the two branches connected to the oxygen atom are named separately and followed by\n\u201cether.\u201d The common name for the compound shown in Example 20.9 is ethylmethyl ether:\n"]], ["block_14", ["5 The IUPAC adopted new nomenclature guidelines in 2013 that require this number to be placed as an \u201cinfix\u201d rather than a prefix.\nFor example, the new name for 2-propanol would be propan-2-ol. Widespread adoption of this new nomenclature will take some\ntime, and students are encouraged to be familiar with both the old and new naming protocols.\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["EXAMPLE 20.8\n"]]], "page_1010": [["block_0", [{"image_0": "1010_0.png", "coords": [72, 57, 189, 79]}]], ["block_1", [" Naming Ethers \n"]], ["block_2", ["Provide the IUPAC and common name for the ether shown here:\n"]], ["block_3", [{"image_1": "1010_1.png", "coords": [72, 150, 189, 173]}]], ["block_4", [" Solution \n"]], ["block_5", ["IUPAC: The molecule is made up of an ethoxy group attached to an ethane chain, so the IUPAC name would be\nethoxyethane.\n"]], ["block_6", ["Common: The groups attached to the oxygen atom are both ethyl groups, so the common name would be\ndiethyl ether.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["Provide the IUPAC and common name for the ether shown:\n"]], ["block_9", [{"image_2": "1010_2.png", "coords": [72, 288, 189, 329]}]], ["block_10", [" Answer: \nIUPAC: 2-methoxypropane; common: isopropylmethyl ether\n"]], ["block_11", ["Ethers can be obtained from alcohols by the elimination of a molecule of water from two molecules of the\nalcohol. For example, when ethanol is treated with a limited amount of sulfuric acid and heated to 140 \u00b0C,\ndiethyl ether and water are formed:\n"]], ["block_12", [{"image_3": "1010_3.png", "coords": [72, 425, 540, 494]}]], ["block_13", ["In the general formula for ethers, R\u2014 O \u2014R, the hydrocarbon groups (R) may be the same or different. Diethyl\nether, the most widely used compound of this class, is a colorless, volatile liquid that is highly flammable. It was\nfirst used in 1846 as an anesthetic, but better anesthetics have now largely taken its place. Diethyl ether and\nother ethers are presently used primarily as solvents for gums, fats, waxes, and resins. Tertiary-butyl methyl\nether, C4H9OCH3 (abbreviated MTBE\u2014italicized portions of names are not counted when ranking the groups\nalphabetically\u2014so butyl comes before methyl in the common name), is used as an additive for gasoline. MTBE\nbelongs to a group of chemicals known as oxygenates due to their capacity to increase the oxygen content of\ngasoline.\n"]], ["block_14", ["Want more practice naming ethers? This brief video review (http://openstax.org/l/16ethers) summarizes the\nnomenclature for ethers.\n"]], ["block_15", ["LINK TO LEARNING\n"]], ["block_16", ["EXAMPLE 20.9\n"]], ["block_17", [" 20.2 \u2022 Alcohols and Ethers \n 997 \n"]]], "page_1011": [["block_0", [" 998 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" Carbohydrates and Diabetes \nCarbohydrates are large biomolecules made up of carbon, hydrogen, and oxygen. The dietary forms of\ncarbohydrates are foods rich in these types of molecules, like pastas, bread, and candy. The name\n\u201ccarbohydrate\u201d comes from the formula of the molecules, which can be described by the general formula\nCm(H2O)n, which shows that they are in a sense \u201ccarbon and water\u201d or \u201chydrates of carbon.\u201d In many cases,\nm and n have the same value, but they can be different. The smaller carbohydrates are generally referred to\nas \u201csugars,\u201d the biochemical term for this group of molecules is \u201csaccharide\u201d from the Greek word for sugar\n(Figure 20.12). Depending on the number of sugar units joined together, they may be classified as\nmonosaccharides (one sugar unit), disaccharides (two sugar units), oligosaccharides (a few sugars), or\npolysaccharides (the polymeric version of sugars\u2014polymers were described in the feature box earlier in\nthis chapter on recycling plastics). The scientific names of sugars can be recognized by the suffix -ose at\nthe end of the name (for instance, fruit sugar is a monosaccharide called \u201cfructose\u201d and milk sugar is a\ndisaccharide called lactose composed of two monosaccharides, glucose and galactose, connected together).\nSugars contain some of the functional groups we have discussed: Note the alcohol groups present in the\nstructures and how monosaccharide units are linked to form a disaccharide by formation of an ether.\n"]], ["block_3", ["Chemistry in Everyday Life\n"]], ["block_4", [" FIGURE 20.12 \nThe illustrations show the molecular structures of fructose, a five-carbon monosaccharide, and\n"]], ["block_5", ["of lactose, a disaccharide composed of two isomeric, six-carbon sugars.\n"]], ["block_6", ["Organisms use carbohydrates for a variety of functions. Carbohydrates can store energy, such as the\npolysaccharides glycogen in animals or starch in plants. They also provide structural support, such as the\npolysaccharide cellulose in plants and the modified polysaccharide chitin in fungi and animals. The sugars\nribose and deoxyribose are components of the backbones of RNA and DNA, respectively. Other sugars play\nkey roles in the function of the immune system, in cell-cell recognition, and in many other biological roles.\n"]], ["block_7", ["Diabetes is a group of metabolic diseases in which a person has a high sugar concentration in their blood\n(Figure 20.13). Diabetes may be caused by insufficient insulin production by the pancreas or by the body\u2019s\ncells not responding properly to the insulin that is produced. In a healthy person, insulin is produced when\nit is needed and functions to transport glucose from the blood into the cells where it can be used for energy.\n"]], ["block_8", [{"image_0": "1011_0.png", "coords": [90, 281, 522, 553]}]]], "page_1012": [["block_0", [" 20.3 Aldehydes, Ketones, Carboxylic Acids, and Esters \n"]], ["block_1", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_2", ["Another class of organic molecules contains a carbon atom connected to an oxygen atom by a double bond,\ncommonly called a carbonyl group. The trigonal planar carbon in the carbonyl group can attach to two other\nsubstituents leading to several subfamilies (aldehydes, ketones, carboxylic acids and esters) described in this\nsection.\n"]], ["block_3", [" Aldehydes and Ketones \n"]], ["block_4", ["Both aldehydes and ketones contain a carbonyl group , a functional group with a carbon-oxygen double bond.\nThe names for aldehyde and ketone compounds are derived using similar nomenclature rules as for alkanes\nand alcohols, and include the class-identifying suffixes -al and -one, respectively:\n"]], ["block_5", ["\u2022\nDescribe the structure and properties of aldehydes, ketones, carboxylic acids and esters\n"]], ["block_6", ["The long-term complications of diabetes can include loss of eyesight, heart disease, and kidney failure.\n"]], ["block_7", ["In 2013, it was estimated that approximately 3.3% of the world\u2019s population (~380 million people) suffered\nfrom diabetes, resulting in over a million deaths annually. Prevention involves eating a healthy diet, getting\nplenty of exercise, and maintaining a normal body weight. Treatment involves all of these lifestyle\npractices and may require injections of insulin.\n"]], ["block_8", ["Even after treatment protocols were introduced, the need to continually monitor their glucose levels posed\na challenge for people with diabetes. The first tests required a doctor or lab, and therefore limited access\nand frequency. Eventually, researchers developed small tablets that would react to the presence of glucose\nin urine, but these still required a relatively complex process. Chemist Helen Free, who was working on\nimprovements to the tablets, conceived a simpler device: a small test strip. With her husband and research\npartner, Alfred Free, she produced the first such product for measuring glucose; soon after, she expanded\nthe technology to provide test strips for other compounds and conditions. While very recent advances\n(such as breath tests, discussed earlier in the text) have shown promise in replacing test strips, they have\nbeen widely used for decades and remain a primary method today.\n"]], ["block_9", [" FIGURE 20.13 \nDiabetes is a disease characterized by high concentrations of glucose in the blood. Treating\n"]], ["block_10", ["diabetes involves making lifestyle changes, monitoring blood-sugar levels, and sometimes insulin injections.\n(credit: \u201cBlausen Medical Communications\u201d/Wikimedia Commons)\n"]], ["block_11", [{"image_0": "1012_0.png", "coords": [162, 252, 450, 468]}]], ["block_12", [" 20.3 \u2022 Aldehydes, Ketones, Carboxylic Acids, and Esters \n 999 \n"]]], "page_1013": [["block_0", [" 1000 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", [{"image_0": "1013_0.png", "coords": [72, 57, 187, 90]}]], ["block_2", ["In an aldehyde, the carbonyl group is bonded to at least one hydrogen atom. In a ketone, the carbonyl group is\nbonded to two carbon atoms:\n"]], ["block_3", [{"image_1": "1013_1.png", "coords": [72, 124, 306, 185]}]], ["block_4", [{"image_2": "1013_2.png", "coords": [72, 188, 306, 281]}]], ["block_5", ["As text, an aldehyde group is represented as \u2013CHO; a ketone is represented as \u2013C(O)\u2013 or \u2013CO\u2013.\n"]], ["block_6", ["In both aldehydes and ketones, the geometry around the carbon atom in the carbonyl group is trigonal planar;\nthe carbon atom exhibits sphybridization. Two of the sporbitals on the carbon atom in the carbonyl group\nare used to form \u03c3 bonds to the other carbon or hydrogen atoms in a molecule. The remaining sphybrid\norbital forms a \u03c3 bond to the oxygen atom. The unhybridized p orbital on the carbon atom in the carbonyl\ngroup overlaps a p orbital on the oxygen atom to form the \u03c0 bond in the double bond.\n"]], ["block_7", ["Like the\nbond in carbon dioxide, the\nbond of a carbonyl group is polar (recall that oxygen is\n"]], ["block_8", ["significantly more electronegative than carbon, and the shared electrons are pulled toward the oxygen atom\nand away from the carbon atom). Many of the reactions of aldehydes and ketones start with the reaction\nbetween a Lewis base and the carbon atom at the positive end of the polar\nbond to yield an unstable\n"]], ["block_9", ["intermediate that subsequently undergoes one or more structural rearrangements to form the final product\n(Figure 20.14).\n"]], ["block_10", [" FIGURE 20.14 \nThe carbonyl group is polar, and the geometry of the bonds around the central carbon is trigonal\n"]], ["block_11", ["planar.\n"]], ["block_12", ["The importance of molecular structure in the reactivity of organic compounds is illustrated by the reactions\nthat produce aldehydes and ketones. We can prepare a carbonyl group by oxidation of an alcohol\u2014for organic\nmolecules, oxidation of a carbon atom is said to occur when a carbon-hydrogen bond is replaced by a carbon-\noxygen bond. The reverse reaction\u2014replacing a carbon-oxygen bond by a carbon-hydrogen bond\u2014is a\nreduction of that carbon atom. Recall that oxygen is generally assigned a \u20132 oxidation number unless it is\nelemental or attached to a fluorine. Hydrogen is generally assigned an oxidation number of +1 unless it is\nattached to a metal. Since carbon does not have a specific rule, its oxidation number is determined\nalgebraically by factoring the atoms it is attached to and the overall charge of the molecule or ion. In general, a\ncarbon atom attached to an oxygen atom will have a more positive oxidation number and a carbon atom\nattached to a hydrogen atom will have a more negative oxidation number. This should fit nicely with your\nunderstanding of the polarity of C\u2013O and C\u2013H bonds. The other reagents and possible products of these\nreactions are beyond the scope of this chapter, so we will focus only on the changes to the carbon atoms:\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", [{"image_3": "1013_3.png", "coords": [247, 454, 364, 496]}]]], "page_1014": [["block_0", [{"image_0": "1014_0.png", "coords": [72, 57, 306, 122]}]], ["block_1", [" Oxidation and Reduction in Organic Chemistry \n"]], ["block_2", ["Methane represents the completely reduced form of an organic molecule that contains one carbon atom.\nSequentially replacing each of the carbon-hydrogen bonds with a carbon-oxygen bond would lead to an\nalcohol, then an aldehyde, then a carboxylic acid (discussed later), and, finally, carbon dioxide:\n"]], ["block_3", ["What are the oxidation numbers for the carbon atoms in the molecules shown here?\n"]], ["block_4", [" Solution \n"]], ["block_5", ["In this example, we can calculate the oxidation number (review the chapter on oxidation-reduction reactions if\nnecessary) for the carbon atom in each case (note how this would become difficult for larger molecules with\nadditional carbon atoms and hydrogen atoms, which is why organic chemists use the definition dealing with\nreplacing C\u2013H bonds with C\u2013O bonds described). For CH4, the carbon atom carries a \u20134 oxidation number (the\nhydrogen atoms are assigned oxidation numbers of +1 and the carbon atom balances that by having an\noxidation number of \u20134). For the alcohol (in this case, methanol), the carbon atom has an oxidation number of\n\u20132 (the oxygen atom is assigned \u20132, the four hydrogen atoms each are assigned +1, and the carbon atom\nbalances the sum by having an oxidation number of \u20132; note that compared to the carbon atom in CH4, this\ncarbon atom has lost two electrons so it was oxidized); for the aldehyde, the carbon atom\u2019s oxidation number is\n0 (\u20132 for the oxygen atom and +1 for each hydrogen atom already balances to 0, so the oxidation number for\nthe carbon atom is 0); for the carboxylic acid, the carbon atom\u2019s oxidation number is +2 (two oxygen atoms\neach at \u20132 and two hydrogen atoms at +1); and for carbon dioxide, the carbon atom\u2019s oxidation number is +4\n(here, the carbon atom needs to balance the \u20134 sum from the two oxygen atoms).\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["Indicate whether the marked carbon atoms in the three molecules here are oxidized or reduced relative to the\nmarked carbon atom in ethanol:\n"]], ["block_8", [{"image_1": "1014_1.png", "coords": [72, 485, 189, 509]}]], ["block_9", ["There is no need to calculate oxidation states in this case; instead, just compare the types of atoms bonded to\nthe marked carbon atoms:\n"]], ["block_10", [{"image_2": "1014_2.png", "coords": [72, 543, 306, 605]}]], ["block_11", [" Answer: \n(a) reduced (bond to oxygen atom replaced by bond to hydrogen atom); (b) oxidized (one bond to hydrogen\natom replaced by one bond to oxygen atom); (c) oxidized (2 bonds to hydrogen atoms have been replaced by\nbonds to an oxygen atom)\n"]], ["block_12", ["Aldehydes are commonly prepared by the oxidation of alcohols whose \u2013OH functional group is located on the\ncarbon atom at the end of the chain of carbon atoms in the alcohol:\n"]], ["block_13", ["EXAMPLE 20.10\n"]], ["block_14", [" 20.3 \u2022 Aldehydes, Ketones, Carboxylic Acids, and Esters \n 1001 \n"]]], "page_1015": [["block_0", [" 1002 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", [{"image_0": "1015_0.png", "coords": [72, 57, 306, 93]}]], ["block_2", ["Alcohols that have their \u2013OH groups in the middle of the chain are necessary to synthesize a ketone, which\nrequires the carbonyl group to be bonded to two other carbon atoms:\n"]], ["block_3", [{"image_1": "1015_1.png", "coords": [72, 127, 306, 163]}]], ["block_4", ["An alcohol with its \u2013OH group bonded to a carbon atom that is bonded to no or one other carbon atom will\nform an aldehyde. An alcohol with its \u2013OH group attached to two other carbon atoms will form a ketone. If\nthree carbons are attached to the carbon bonded to the \u2013OH, the molecule will not have a C\u2013H bond to be\nreplaced, so it will not be susceptible to oxidation.\n"]], ["block_5", ["Formaldehyde, an aldehyde with the formula HCHO, is a colorless gas with a pungent and irritating odor. It is\nsold in an aqueous solution called formalin, which contains about 37% formaldehyde by weight. Formaldehyde\ncauses coagulation of proteins, so it kills bacteria (and any other living organism) and stops many of the\nbiological processes that cause tissue to decay. Thus, formaldehyde is used for preserving tissue specimens\nand embalming bodies. It is also used to sterilize soil or other materials. Formaldehyde is used in the\nmanufacture of Bakelite, a hard plastic having high chemical and electrical resistance.\n"]], ["block_6", ["Dimethyl ketone, CH3COCH3, commonly called acetone, is the simplest ketone. It is made commercially by\nfermenting corn or molasses, or by oxidation of 2-propanol. Acetone is a colorless liquid. Among its many uses\nare as a solvent for lacquer (including fingernail polish), cellulose acetate, cellulose nitrate, acetylene, plastics,\nand varnishes; as a paint and varnish remover; and as a solvent in the manufacture of pharmaceuticals and\nchemicals.\n"]], ["block_7", [" Carboxylic Acids and Esters \n"]], ["block_8", ["The odor of vinegar is caused by the presence of acetic acid, a carboxylic acid, in the vinegar. The odor of ripe\nbananas and many other fruits is due to the presence of esters, compounds that can be prepared by the\nreaction of a carboxylic acid with an alcohol. Because esters do not have hydrogen bonds between molecules,\nthey have lower vapor pressures than the alcohols and carboxylic acids from which they are derived (see\nFigure 20.15).\n"]], ["block_9", [" Access for free at openstax.org \n"]]], "page_1016": [["block_0", [{"image_0": "1016_0.png", "coords": [72, 57, 540, 343]}]], ["block_1", ["Both carboxylic acids and esters contain a carbonyl group with a second oxygen atom bonded to the carbon\natom in the carbonyl group by a single bond. In a carboxylic acid, the second oxygen atom also bonds to a\nhydrogen atom. In an ester, the second oxygen atom bonds to another carbon atom. The names for carboxylic\nacids and esters include prefixes that denote the lengths of the carbon chains in the molecules and are derived\nfollowing nomenclature rules similar to those for inorganic acids and salts (see these examples):\n"]], ["block_2", [{"image_1": "1016_1.png", "coords": [72, 434, 306, 514]}]], ["block_3", ["The functional groups for an acid and for an ester are shown in red in these formulas.\n"]], ["block_4", ["The hydrogen atom in the functional group of a carboxylic acid will react with a base to form an ionic salt:\n"]], ["block_5", [{"image_2": "1016_2.png", "coords": [72, 555, 540, 634]}]], ["block_6", ["Carboxylic acids are weak acids (see the chapter on acids and bases), meaning they are not 100% ionized in\nwater. Generally only about 1% of the molecules of a carboxylic acid dissolved in water are ionized at any given\ntime. The remaining molecules are undissociated in solution.\n"]], ["block_7", ["We prepare carboxylic acids by the oxidation of aldehydes or alcohols whose \u2013OH functional group is located\non the carbon atom at the end of the chain of carbon atoms in the alcohol:\n"]], ["block_8", [" FIGURE 20.15 \nEsters are responsible for the odors associated with various plants and their fruits.\n"]], ["block_9", [" 20.3 \u2022 Aldehydes, Ketones, Carboxylic Acids, and Esters \n 1003 \n"]]], "page_1017": [["block_0", [" 1004 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", ["The simplest carboxylic acid is formic acid, HCO2H, known since 1670. Its name comes from the Latin word\nformicus, which means \u201cant\u201d; it was first isolated by the distillation of red ants. It is partially responsible for\nthe pain and irritation of ant and wasp stings, and is responsible for a characteristic odor of ants that can be\nsometimes detected in their nests.\n"]], ["block_2", [{"image_0": "1017_0.png", "coords": [72, 57, 423, 132]}]], ["block_3", ["Esters are produced by the reaction of acids with alcohols. For example, the ester ethyl acetate,\nCH3CO2CH2CH3, is formed when acetic acid reacts with ethanol:\n"]], ["block_4", [{"image_1": "1017_1.png", "coords": [72, 166, 423, 236]}]], ["block_5", ["Acetic acid, CH3CO2H, constitutes 3\u20136% vinegar. Cider vinegar is produced by allowing apple juice to ferment\nwithout oxygen present. Yeast cells present in the juice carry out the fermentation reactions. The fermentation\nreactions change the sugar present in the juice to ethanol, then to acetic acid. Pure acetic acid has a\npenetrating odor and produces painful burns. It is an excellent solvent for many organic and some inorganic\ncompounds, and it is essential in the production of cellulose acetate, a component of many synthetic fibers\nsuch as rayon.\n"]], ["block_6", ["The distinctive and attractive odors and flavors of many flowers, perfumes, and ripe fruits are due to the\npresence of one or more esters (Figure 20.16). Among the most important of the natural esters are fats (such as\nlard, tallow, and butter) and oils (such as linseed, cottonseed, and olive oils), which are esters of the trihydroxyl\nalcohol glycerine, C3H5(OH)3, with large carboxylic acids, such as palmitic acid, CH3(CH2)14CO2H, stearic acid,\nCH3(CH2)16CO2H, and oleic acid,\nOleic acid is an unsaturated acid; it\n"]], ["block_7", ["contains a\ndouble bond. Palmitic and stearic acids are saturated acids that contain no double or triple\n"]], ["block_8", ["bonds.\n"]], ["block_9", [" FIGURE 20.16 \nOver 350 different volatile molecules (many members of the ester family) have been identified in\n"]], ["block_10", ["strawberries. (credit: Rebecca Siegel)\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", [{"image_2": "1017_2.png", "coords": [189, 472, 423, 647]}]]], "page_1018": [["block_0", [" 20.4 Amines and Amides \n"]], ["block_1", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_2", [" Amines are molecules that contain carbon-nitrogen bonds. The nitrogen atom in an amine has a lone pair of\nelectrons and three bonds to other atoms, either carbon or hydrogen. Various nomenclatures are used to\nderive names for amines, but all involve the class-identifying suffix \u2013ine as illustrated here for a few simple\nexamples:\n"]], ["block_3", [{"image_0": "1018_0.png", "coords": [72, 194, 306, 248]}]], ["block_4", ["In some amines, the nitrogen atom replaces a carbon atom in an aromatic hydrocarbon. Pyridine (Figure\n20.17) is one such heterocyclic amine. A heterocyclic compound contains atoms of two or more different\nelements in its ring structure.\n"]], ["block_5", [" DNA in Forensics and Paternity \nThe genetic material for all living things is a polymer of four different molecules, which are themselves a\ncombination of three subunits. The genetic information, the code for developing an organism, is contained in\nthe specific sequence of the four molecules, similar to the way the letters of the alphabet can be sequenced to\nform words that convey information. The information in a DNA sequence is used to form two other types of\npolymers, one of which are proteins. The proteins interact to form a specific type of organism with individual\ncharacteristics.\n"]], ["block_6", ["A genetic molecule is called DNA, which stands for deoxyribonucleic acid. The four molecules that make up\nDNA are called nucleotides. Each nucleotide consists of a single- or double-ringed molecule containing\nnitrogen, carbon, oxygen, and hydrogen called a nitrogenous base. Each base is bonded to a five-carbon sugar\ncalled deoxyribose. The sugar is in turn bonded to a phosphate group\nWhen new DNA is made, a\n"]], ["block_7", ["polymerization reaction occurs that binds the phosphate group of one nucleotide to the sugar group of a\nsecond nucleotide. The nitrogenous bases of each nucleotide stick out from this sugar-phosphate backbone.\nDNA is actually formed from two such polymers coiled around each other and held together by hydrogen\nbonds between the nitrogenous bases. Thus, the two backbones are on the outside of the coiled pair of strands,\nand the bases are on the inside. The shape of the two strands wound around each other is called a double helix\n(see Figure 20.18).\n"]], ["block_8", ["It probably makes sense that the sequence of nucleotides in the DNA of a cat differs from those of a dog. But it\nis also true that the sequences of the DNA in the cells of two individual pugs differ. Likewise, the sequences of\nDNA in you and a sibling differ (unless your sibling is an identical twin), as do those between you and an\nunrelated individual. However, the DNA sequences of two related individuals are more similar than the\nsequences of two unrelated individuals, and these similarities in sequence can be observed in various ways.\n"]], ["block_9", ["\u2022\nDescribe the structure and properties of an amine\n"]], ["block_10", ["\u2022\nDescribe the structure and properties of an amide\n"]], ["block_11", ["HOW SCIENCES INTERCONNECT\n"]], ["block_12", [" FIGURE 20.17 \nThe illustration shows one of the resonance structures of pyridine.\n"]], ["block_13", [{"image_1": "1018_1.png", "coords": [247, 295, 364, 376]}]], ["block_14", [" 20.4 \u2022 Amines and Amides \n 1005 \n"]]], "page_1019": [["block_0", [" 1006 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", ["This is the principle behind DNA fingerprinting, which is a method used to determine whether two DNA\nsamples came from related (or the same) individuals or unrelated individuals.\n"]], ["block_2", [" FIGURE 20.18 \nDNA is an organic molecule and the genetic material for all living organisms. (a) DNA is a double\n"]], ["block_3", ["helix consisting of two single DNA strands hydrogen bonded together at each nitrogenous base. (b) This detail\nshows the hydrogen bonding (dotted lines) between nitrogenous bases on each DNA strand and the way in which\neach nucleotide is joined to the next, forming a backbone of sugars and phosphate groups along each strand. (c)\nThis detail shows the structure of one of the four nucleotides that makes up the DNA polymer. Each nucleotide\nconsists of a nitrogenous base (a double-ring molecule, in this case), a five-carbon sugar (deoxyribose), and a\nphosphate group.\n"]], ["block_4", ["Using similarities in sequences, technicians can determine whether a man is the father of a child (the identity\nof the mother is rarely in doubt, except in the case of an adopted child and a potential birth mother). Likewise,\nforensic geneticists can determine whether a crime scene sample of human tissue, such as blood or skin cells,\ncontains DNA that matches exactly the DNA of a suspect.\n"]], ["block_5", ["Watch this video animation (http://openstax.org/l/16dnapackaging) of how DNA is packaged for a visual lesson\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [{"image_0": "1019_0.png", "coords": [90, 89, 522, 521]}]], ["block_8", ["LINK TO LEARNING\n"]]], "page_1020": [["block_0", ["in its structure.\n"]], ["block_1", ["Like ammonia, amines are weak bases due to the lone pair of electrons on their nitrogen atoms:\n"]], ["block_2", [{"image_0": "1020_0.png", "coords": [72, 109, 423, 280]}]], ["block_3", ["The basicity of an amine\u2019s nitrogen atom plays an important role in much of the compound\u2019s chemistry. Amine\nfunctional groups are found in a wide variety of compounds, including natural and synthetic dyes, polymers,\nvitamins, and medications such as penicillin and codeine. They are also found in many molecules essential to\nlife, such as amino acids, hormones, neurotransmitters, and DNA.\n"]], ["block_4", [" Addictive Alkaloids \nSince ancient times, plants have been used for medicinal purposes. One class of substances, called alkaloids,\nfound in many of these plants has been isolated and found to contain cyclic molecules with an amine\nfunctional group. These amines are bases. They can react with H3Oin a dilute acid to form an ammonium\nsalt, and this property is used to extract them from the plant:\n"]], ["block_5", ["The name alkaloid means \u201clike an alkali.\u201d Thus, an alkaloid reacts with acid. The free compound can be\nrecovered after extraction by reaction with a base:\n"]], ["block_6", ["The structures of many naturally occurring alkaloids have profound physiological and psychotropic effects in\nhumans. Examples of these drugs include nicotine, morphine, codeine, and heroin. The plant produces these\nsubstances, collectively called secondary plant compounds, as chemical defenses against the numerous pests\nthat attempt to feed on the plant:\n"]], ["block_7", ["HOW SCIENCES INTERCONNECT\n"]], ["block_8", [" 20.4 \u2022 Amines and Amides \n 1007 \n"]]], "page_1021": [["block_0", [" 1008 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", [{"image_0": "1021_0.png", "coords": [72, 57, 504, 374]}]], ["block_2", ["In these diagrams, as is common in representing structures of large organic compounds, carbon atoms in the\nrings and the hydrogen atoms bonded to them have been omitted for clarity. The solid wedges indicate bonds\nthat extend out of the page. The dashed wedges indicate bonds that extend into the page. Notice that small\nchanges to a part of the molecule change the properties of morphine, codeine, and heroin. Morphine, a strong\nnarcotic used to relieve pain, contains two hydroxyl functional groups, located at the bottom of the molecule in\nthis structural formula. Changing one of these hydroxyl groups to a methyl ether group forms codeine, a less\npotent drug used as a local anesthetic. If both hydroxyl groups are converted to esters of acetic acid, the\npowerfully addictive drug heroin results (Figure 20.19).\n"]], ["block_3", [" FIGURE 20.19 \nPoppies can be used in the production of opium, a plant latex that contains morphine from which\n"]], ["block_4", ["other opiates, such as heroin, can be synthesized. (credit: Karen Roe)\n"]], ["block_5", [" Amides are molecules that contain nitrogen atoms connected to the carbon atom of a carbonyl group. Like\namines, various nomenclature rules may be used to name amides, but all include use of the class-specific\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [{"image_1": "1021_1.png", "coords": [190, 484, 421, 657]}]]], "page_1022": [["block_0", ["suffix -amide:\n"]], ["block_1", [{"image_0": "1022_0.png", "coords": [72, 76, 306, 203]}]], ["block_2", ["Amides can be produced when carboxylic acids react with amines or ammonia in a process called amidation.\nA water molecule is eliminated from the reaction, and the amide is formed from the remaining pieces of the\ncarboxylic acid and the amine (note the similarity to formation of an ester from a carboxylic acid and an\nalcohol discussed in the previous section):\n"]], ["block_3", [{"image_1": "1022_1.png", "coords": [72, 263, 540, 337]}]], ["block_4", ["The reaction between amines and carboxylic acids to form amides is biologically important. It is through this\nreaction that amino acids (molecules containing both amine and carboxylic acid substituents) link together in\na polymer to form proteins.\n"]], ["block_5", [" Proteins and Enzymes \nProteins are large biological molecules made up of long chains of smaller molecules called amino acids.\nOrganisms rely on proteins for a variety of functions\u2014proteins transport molecules across cell membranes,\nreplicate DNA, and catalyze metabolic reactions, to name only a few of their functions. The properties of\nproteins are functions of the combination of amino acids that compose them and can vary greatly. Interactions\nbetween amino acid sequences in the chains of proteins result in the folding of the chain into specific, three-\ndimensional structures that determine the protein\u2019s activity.\n"]], ["block_6", ["Amino acids are organic molecules that contain an amine functional group (\u2013NH2), a carboxylic acid\nfunctional group (\u2013COOH), and a side chain (that is specific to each individual amino acid). Most living things\nbuild proteins from the same 20 different amino acids. Amino acids connect by the formation of a peptide\nbond, which is a covalent bond formed between two amino acids when the carboxylic acid group of one amino\nacid reacts with the amine group of the other amino acid. The formation of the bond results in the production\nof a molecule of water (in general, reactions that result in the production of water when two other molecules\ncombine are referred to as condensation reactions). The resulting bond\u2014between the carbonyl group carbon\natom and the amine nitrogen atom is called a peptide link or peptide bond. Since each of the original amino\nacids has an unreacted group (one has an unreacted amine and the other an unreacted carboxylic acid), more\npeptide bonds can form to other amino acids, extending the structure. (Figure 20.20) A chain of connected\namino acids is called a polypeptide. Proteins contain at least one long polypeptide chain.\n"]], ["block_7", ["HOW SCIENCES INTERCONNECT\n"]], ["block_8", [" 20.4 \u2022 Amines and Amides \n 1009 \n"]]], "page_1023": [["block_0", [" 1010 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", [" FIGURE 20.20 \nThis condensation reaction forms a dipeptide from two amino acids and leads to the formation of\n"]], ["block_2", ["water.\n"]], ["block_3", ["Enzymes are large biological molecules, mostly composed of proteins, which are responsible for the thousands\nof metabolic processes that occur in living organisms. Enzymes are highly specific catalysts; they speed up the\nrates of certain reactions. Enzymes function by lowering the activation energy of the reaction they are\ncatalyzing, which can dramatically increase the rate of the reaction. Most reactions catalyzed by enzymes have\nrates that are millions of times faster than the noncatalyzed version. Like all catalysts, enzymes are not\nconsumed during the reactions that they catalyze. Enzymes do differ from other catalysts in how specific they\nare for their substrates (the molecules that an enzyme will convert into a different product). Each enzyme is\nonly capable of speeding up one or a few very specific reactions or types of reactions. Since the function of\nenzymes is so specific, the lack or malfunctioning of an enzyme can lead to serious health consequences. One\ndisease that is the result of an enzyme malfunction is phenylketonuria. In this disease, the enzyme that\ncatalyzes the first step in the degradation of the amino acid phenylalanine is not functional (Figure 20.21).\nUntreated, this can lead to an accumulation of phenylalanine, which can lead to intellectual disabilities.\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", [{"image_0": "1023_0.png", "coords": [130, 57, 481, 281]}]]], "page_1024": [["block_0", [" FIGURE 20.21 \nA computer rendering shows the three-dimensional structure of the enzyme phenylalanine\n"]], ["block_1", ["hydroxylase. In the disease phenylketonuria, a defect in the shape of phenylalanine hydroxylase causes it to lose its\nfunction in breaking down phenylalanine.\n"]], ["block_2", ["Chemistry in Everyday Life\n"]], ["block_3", [" Kevlar \n Kevlar (Figure 20.22) is a synthetic polymer made from two monomers 1,4-phenylene-diamine and\nterephthaloyl chloride ( Kevlar is a registered trademark of DuPont). The material was developed by Susan\nKwolek while she worked to find a replacement for steel in tires. Kwolek's work involved synthesizing\npolyamides and dissolving them in solvents, then spinning the resulting solution into fibers. One of her\nsolutions proved to be quite different in initial appearance and structure. And once spun, the resulting\nfibers were particularly strong. From this initial discovery, Kevlar was created. The material has a high\ntensile strength-to-weight ratio (it is about 5 times stronger than an equal weight of steel), making it useful\nfor many applications from bicycle tires to sails to body armor.\n"]], ["block_4", ["The material owes much of its strength to hydrogen bonds between polymer chains (refer back to the\nchapter on intermolecular interactions). These bonds form between the carbonyl group oxygen atom\n(which has a partial negative charge due to oxygen\u2019s electronegativity) on one monomer and the partially\npositively charged hydrogen atom in the N\u2013H bond of an adjacent monomer in the polymer structure (see\ndashed line in Figure 20.23). There is additional strength derived from the interaction between the\nunhybridized p orbitals in the six-membered rings, called aromatic stacking.\n"]], ["block_5", [" FIGURE 20.22 \nThis illustration shows the formula for polymeric Kevlar.\n"]], ["block_6", [{"image_0": "1024_0.png", "coords": [189, 57, 423, 332]}]], ["block_7", [{"image_1": "1024_1.png", "coords": [189, 542, 423, 622]}]], ["block_8", [" 20.4 \u2022 Amines and Amides \n 1011 \n"]]], "page_1025": [["block_0", [" 1012 \n 20 \u2022 Organic Chemistry \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" FIGURE 20.23 \nThe diagram shows the polymer structure of Kevlar, with hydrogen bonds between polymer\n"]], ["block_3", ["chains represented by dotted lines.\n"]], ["block_4", ["Kevlar may be best known as a component of body armor, combat helmets, and face masks. Since the\n1980s, the US military has used Kevlar as a component of the PASGT (personal armor system for ground\ntroops) helmet and vest. Kevlar is also used to protect armored fighting vehicles and aircraft carriers.\nCivilian applications include protective gear for emergency service personnel such as body armor for\npolice officers and heat-resistant clothing for fire fighters. Kevlar based clothing is considerably lighter and\nthinner than equivalent gear made from other materials (Figure 20.24). Beyond Kevlar, Susan Kwolek was\ninstrumental in the development of Nomex, a fireproof material, and was also involved in the creation of\nLycra. She became just the fourth woman inducted into the National Inventors Hall of Fame, and received a\nnumber of other awards for her significant contributions to science and society.\n"]], ["block_5", [" FIGURE 20.24 \n(a) These soldiers are sorting through pieces of a Kevlar helmet that helped absorb a grenade\n"]], ["block_6", ["blast. Kevlar is also used to make (b) canoes and (c) marine mooring lines. (credit a: modification of work by\n\u201cCla68\u201d/Wikimedia Commons; credit b: modification of work by \u201cOakleyOriginals\u201d/Flickr; credit c: modification\nof work by Casey H. Kyhl)\n"]], ["block_7", ["In addition to its better-known uses, Kevlar is also often used in cryogenics for its very low thermal\nconductivity (along with its high strength). Kevlar maintains its high strength when cooled to the\ntemperature of liquid nitrogen (\u2013196 \u00b0C).\n"]], ["block_8", [{"image_0": "1025_0.png", "coords": [90, 57, 522, 355]}]], ["block_9", [{"image_1": "1025_1.png", "coords": [90, 509, 522, 611]}]]], "page_1026": [["block_0", ["The table here summarizes the structures discussed in this chapter:\n"]], ["block_1", [{"image_0": "1026_0.png", "coords": [72, 76, 540, 508]}]], ["block_2", [" 20.4 \u2022 Amines and Amides \n 1013 \n"]]], "page_1027": [["block_0", [" 1014 \n 20 \u2022 Key Terms \n"]], ["block_1", [" Key Terms \n"]], ["block_2", [" addition reaction \nreaction in which a double\n"]], ["block_3", [" alcohol \norganic compound with a hydroxyl group\n"]], ["block_4", [" aldehyde \norganic compound containing a carbonyl\n"]], ["block_5", [" alkane \nmolecule consisting of only carbon and\n"]], ["block_6", [" alkene \nmolecule consisting of carbon and\n"]], ["block_7", [" alkyl group \nsubstituent, consisting of an alkane\n"]], ["block_8", [" alkyne \nmolecule consisting of carbon and\n"]], ["block_9", [" amide \norganic molecule that features a nitrogen\n"]], ["block_10", [" amine \norganic molecule in which a nitrogen atom\n"]], ["block_11", [" aromatic hydrocarbon \ncyclic molecule consisting\n"]], ["block_12", [" carbonyl group \ncarbon atom double bonded to an\n"]], ["block_13", [" Summary \n"]], ["block_14", [" 20.1 Hydrocarbons \n"]], ["block_15", ["Strong, stable bonds between carbon atoms produce\ncomplex molecules containing chains, branches,\nand rings. The chemistry of these compounds is\ncalled organic chemistry. Hydrocarbons are organic\ncompounds composed of only carbon and hydrogen.\nThe alkanes are saturated hydrocarbons\u2014that is,\nhydrocarbons that contain only single bonds.\nAlkenes contain one or more carbon-carbon double\nbonds. Alkynes contain one or more carbon-carbon\ntriple bonds. Aromatic hydrocarbons contain ring\nstructures with delocalized \u03c0 electron systems.\n"]], ["block_16", [" 20.2 Alcohols and Ethers \n"]], ["block_17", ["Many organic compounds that are not hydrocarbons\ncan be thought of as derivatives of hydrocarbons. A\nhydrocarbon derivative can be formed by replacing\none or more hydrogen atoms of a hydrocarbon by a\n"]], ["block_18", [" Access for free at openstax.org \n"]], ["block_19", ["carbon-carbon bond forms a single carbon-\ncarbon bond by the addition of a reactant. Typical\nreaction for an alkene.\n"]], ["block_20", ["(\u2013OH) bonded to a carbon atom\n"]], ["block_21", ["group bonded to two hydrogen atoms or a\nhydrogen atom and a carbon substituent\n"]], ["block_22", ["hydrogen atoms connected by single (\u03c3) bonds\n"]], ["block_23", ["hydrogen containing at least one carbon-carbon\ndouble bond\n"]], ["block_24", ["missing one hydrogen atom, attached to a larger\nstructure\n"]], ["block_25", ["hydrogen containing at least one carbon-carbon\ntriple bond\n"]], ["block_26", ["atom connected to the carbon atom in a carbonyl\ngroup\n"]], ["block_27", ["is bonded to one or more alkyl group\n"]], ["block_28", ["of carbon and hydrogen with delocalized\nalternating carbon-carbon single and double\nbonds, resulting in enhanced stability\n"]], ["block_29", [" carboxylic acid \norganic compound containing a\n"]], ["block_30", [" ester \norganic compound containing a carbonyl\n"]], ["block_31", [" ether \norganic compound with an oxygen atom that\n"]], ["block_32", [" functional group \npart of an organic molecule that\n"]], ["block_33", [" ketone \norganic compound containing a carbonyl\n"]], ["block_34", [" organic compound \nnatural or synthetic compound\n"]], ["block_35", [" saturated hydrocarbon \nmolecule containing\n"]], ["block_36", [" skeletal structure \nshorthand method of drawing\n"]], ["block_37", [" substituent \nbranch or functional group that\n"]], ["block_38", [" substitution reaction \nreaction in which one atom\n"]], ["block_39", ["functional group, which contains at least one atom of\nan element other than carbon or hydrogen. The\nproperties of hydrocarbon derivatives are\ndetermined largely by the functional group. The \u2013OH\ngroup is the functional group of an alcohol. The\n\u2013R\u2013O\u2013R\u2013 group is the functional group of an ether.\n"]], ["block_40", [" 20.3 Aldehydes, Ketones, Carboxylic Acids, \n and Esters \n"]], ["block_41", ["Functional groups related to the carbonyl group\ninclude the \u2013CHO group of an aldehyde, the \u2013CO\u2013\ngroup of a ketone, the \u2013CO2H group of a carboxylic\nacid, and the \u2013CO2R group of an ester. The carbonyl\ngroup, a carbon-oxygen double bond, is the key\nstructure in these classes of organic molecules:\nAldehydes contain at least one hydrogen atom\nattached to the carbonyl carbon atom, ketones\ncontain two carbon groups attached to the carbonyl\ncarbon atom, carboxylic acids contain a hydroxyl\n"]], ["block_42", ["oxygen atom\n"]], ["block_43", ["carbonyl group with an attached hydroxyl group\n"]], ["block_44", ["group with an attached oxygen atom that is\nbonded to a carbon substituent\n"]], ["block_45", ["is bonded to two carbon atoms\n"]], ["block_46", ["imparts a specific chemical reactivity to the\nmolecule\n"]], ["block_47", ["group with two carbon substituents attached to it\n"]], ["block_48", ["that contains carbon\n"]], ["block_49", ["carbon and hydrogen that has only single bonds\nbetween carbon atoms\n"]], ["block_50", ["organic molecules in which carbon atoms are\nrepresented by the ends of lines and bends in\nbetween lines, and hydrogen atoms attached to\nthe carbon atoms are not shown (but are\nunderstood to be present by the context of the\nstructure)\n"]], ["block_51", ["replaces hydrogen atoms in a larger hydrocarbon\nchain\n"]], ["block_52", ["replaces another in a molecule\n"]]], "page_1028": [["block_0", ["group attached to the carbonyl carbon atom, and\nesters contain an oxygen atom attached to another\ncarbon group connected to the carbonyl carbon\natom. All of these compounds contain oxidized\ncarbon atoms relative to the carbon atom of an\nalcohol group.\n"]], ["block_1", [" 20.4 Amines and Amides \n"]], ["block_2", ["The addition of nitrogen into an organic framework\n"]], ["block_3", [" Exercises \n"]], ["block_4", [" 20.1 Hydrocarbons \n"]], ["block_5", [" 1 . Write the chemical formula and Lewis structure of the following, each of which contains five carbon atoms:\n"]], ["block_6", [" 2 . What is the difference between the hybridization of carbon atoms\u2019 valence orbitals in saturated and\n"]], ["block_7", [" 3 . On a microscopic level, how does the reaction of bromine with a saturated hydrocarbon differ from its\n"]], ["block_8", [" 4 . On a microscopic level, how does the reaction of bromine with an alkene differ from its reaction with an\n"]], ["block_9", [" 5 . Explain why unbranched alkenes can form geometric isomers while unbranched alkanes cannot. Does\n"]], ["block_10", [" 6 . Explain why these two molecules are not isomers:\n"]], ["block_11", [" 7 . Explain why these two molecules are not isomers:\n"]], ["block_12", [" 8 . How does the carbon-atom hybridization change when polyethylene is prepared from ethylene?\n 9 . Write the Lewis structure and molecular formula for each of the following hydrocarbons:\n"]], ["block_13", ["(a) an alkane\n(b) an alkene\n(c) an alkyne\n"]], ["block_14", ["unsaturated hydrocarbons?\n"]], ["block_15", ["reaction with an unsaturated hydrocarbon? How are they similar?\n"]], ["block_16", ["alkyne? How are they similar?\n"]], ["block_17", ["this explanation involve the macroscopic domain or the microscopic domain?\n"]], ["block_18", [{"image_0": "1028_0.png", "coords": [89, 387, 449, 478]}]], ["block_19", [{"image_1": "1028_1.png", "coords": [89, 494, 449, 590]}]], ["block_20", ["(a) hexane\n(b) 3-methylpentane\n(c) cis-3-hexene\n(d) 4-methyl-1-pentene\n(e) 3-hexyne\n(f) 4-methyl-2-pentyne\n"]], ["block_21", ["leads to two families of molecules. Compounds\ncontaining a nitrogen atom bonded in a\nhydrocarbon framework are classified as amines.\nCompounds that have a nitrogen atom bonded to\none side of a carbonyl group are classified as\namides. Amines are a basic functional group.\nAmines and carboxylic acids can combine in a\ncondensation reaction to form amides.\n"]], ["block_22", [" 20 \u2022 Exercises \n 1015 \n"]]], "page_1029": [["block_0", [" 1016 \n 20 \u2022 Exercises \n"]], ["block_1", [" 10 . Write the chemical formula, condensed formula, and Lewis structure for each of the following\n"]], ["block_2", [" 11 . Give the complete IUPAC name for each of the following compounds:\n"]], ["block_3", [" 12 . Give the complete IUPAC name for each of the following compounds:\n"]], ["block_4", [" 13 . Butane is used as a fuel in disposable lighters. Write the Lewis structure for each isomer of butane.\n 14 . Write Lewis structures and name the five structural isomers of hexane.\n 15 . Write Lewis structures for the cis\u2013trans isomers of\n 16 . Write structures for the three isomers of the aromatic hydrocarbon xylene, C6H4(CH3)2.\n 17 . Isooctane is the common name of the isomer of C8H18 used as the standard of 100 for the gasoline octane\n"]], ["block_5", [" 18 . Write Lewis structures and IUPAC names for the alkyne isomers of C4H6.\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", ["hydrocarbons:\n(a) heptane\n(b) 3-methylhexane\n(c) trans-3-heptene\n(d) 4-methyl-1-hexene\n(e) 2-heptyne\n(f) 3,4-dimethyl-1-pentyne\n"]], ["block_8", ["(a) CH3CH2CBr2CH3\n(b) (CH3)3CCl\n(c)\n"]], ["block_9", [{"image_0": "1029_0.png", "coords": [91, 208, 316, 243]}]], ["block_10", ["(d)\n(e)\n"]], ["block_11", [{"image_1": "1029_1.png", "coords": [91, 271, 316, 307]}]], ["block_12", ["(f)\n"]], ["block_13", [{"image_2": "1029_2.png", "coords": [91, 323, 316, 370]}]], ["block_14", ["(g)\n"]], ["block_15", ["(a) (CH3)2CHF\n(b) CH3CHClCHClCH3\n(c)\n"]], ["block_16", [{"image_3": "1029_3.png", "coords": [91, 436, 316, 471]}]], ["block_17", ["(d)\n(e)\n"]], ["block_18", [{"image_4": "1029_4.png", "coords": [91, 499, 316, 535]}]], ["block_19", ["(f)\n"]], ["block_20", ["rating:\n"]], ["block_21", [{"image_5": "1029_5.png", "coords": [91, 627, 316, 681]}]], ["block_22", ["(a) What is the IUPAC name for the compound?\n(b) Name the other isomers that contain a five-carbon chain with three methyl substituents.\n"]]], "page_1030": [["block_0", [" 19 . Write Lewis structures and IUPAC names for all isomers of C4H9Cl.\n 20 . Name and write the structures of all isomers of the propyl and butyl alkyl groups.\n 21 . Write the structures for all the isomers of the \u2013C5H11 alkyl group.\n 22 . Write Lewis structures and describe the molecular geometry at each carbon atom in the following\n"]], ["block_1", [" 23 . Benzene is one of the compounds used as an octane enhancer in unleaded gasoline. It is manufactured by\n"]], ["block_2", [" 24 . Teflon is prepared by the polymerization of tetrafluoroethylene. Write the equation that describes the\n"]], ["block_3", [" 25 . Write two complete, balanced equations for each of the following reactions, one using condensed formulas\n"]], ["block_4", [" 26 . Write two complete, balanced equations for each of the following reactions, one using condensed formulas\n"]], ["block_5", [" 27 . What mass of 2-bromopropane could be prepared from 25.5 g of propene? Assume a 100% yield of\n"]], ["block_6", [" 28 . Acetylene is a very weak acid; however, it will react with moist silver(I) oxide and form water and a\n"]], ["block_7", [" 29 . Ethylene can be produced by the pyrolysis of ethane:\n"]], ["block_8", [" 20.2 Alcohols and Ethers \n"]], ["block_9", [" 30 . Why do the compounds hexane, hexanol, and hexene have such similar names?\n 31 . Write condensed formulas and provide IUPAC names for the following compounds:\n"]], ["block_10", ["compounds:\n(a) cis-3-hexene\n(b) cis-1-chloro-2-bromoethene\n(c) 2-pentyne\n(d) trans-6-ethyl-7-methyl-2-octene\n"]], ["block_11", ["the catalytic conversion of acetylene to benzene:\n"]], ["block_12", ["Draw Lewis structures for these compounds, with resonance structures as appropriate, and determine the\nhybridization of the carbon atoms in each.\n"]], ["block_13", ["polymerization using Lewis symbols.\n"]], ["block_14", ["and one using Lewis structures.\n(a) 1 mol of 1-butyne reacts with 2 mol of iodine.\n(b) Pentane is burned in air.\n"]], ["block_15", ["and one using Lewis structures.\n(a) 2-butene reacts with chlorine.\n(b) benzene burns in air.\n"]], ["block_16", ["product.\n"]], ["block_17", ["compound composed of silver and carbon. Addition of a solution of HCl to a 0.2352-g sample of the\ncompound of silver and carbon produced acetylene and 0.2822 g of AgCl.\n(a) What is the empirical formula of the compound of silver and carbon?\n(b) The production of acetylene on addition of HCl to the compound of silver and carbon suggests that the\ncarbon is present as the acetylide ion,\n. Write the formula of the compound showing the acetylide\n"]], ["block_18", ["ion.\n"]], ["block_19", ["How many kilograms of ethylene is produced by the pyrolysis of 1.000\n10kg of ethane, assuming a\n"]], ["block_20", ["100.0% yield?\n"]], ["block_21", ["(a) ethyl alcohol (in beverages)\n(b) methyl alcohol (used as a solvent, for example, in shellac)\n(c) ethylene glycol (antifreeze)\n(d) isopropyl alcohol (used in rubbing alcohol)\n(e) glycerine\n"]], ["block_22", [" 20 \u2022 Exercises \n 1017 \n"]]], "page_1031": [["block_0", [" 1018 \n 20 \u2022 Exercises \n"]], ["block_1", [" 32 . Give the complete IUPAC name for each of the following compounds:\n"]], ["block_2", [" 33 . Give the complete IUPAC name and the common name for each of the following compounds:\n"]], ["block_3", [" 34 . Write the condensed structures of both isomers with the formula C2H6O. Label the functional group of\n"]], ["block_4", [" 35 . Write the condensed structures of all isomers with the formula C2H6O2. Label the functional group (or\n"]], ["block_5", [" 36 . Draw the condensed formulas for each of the following compounds:\n"]], ["block_6", [" 37 . MTBE, Methyl tert-butyl ether, CH3OC(CH3)3, is used as an oxygen source in oxygenated gasolines. MTBE\n"]], ["block_7", [" 38 . Write two complete balanced equations for each of the following reactions, one using condensed formulas\n"]], ["block_8", [" 39 . Write two complete balanced equations for each of the following reactions, one using condensed formulas\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["(a)\n"]], ["block_11", [{"image_0": "1031_0.png", "coords": [91, 82, 208, 157]}]], ["block_12", ["(b)\n"]], ["block_13", [{"image_1": "1031_1.png", "coords": [91, 172, 208, 229]}]], ["block_14", ["(c)\n"]], ["block_15", [{"image_2": "1031_2.png", "coords": [91, 244, 325, 320]}]], ["block_16", ["(a)\n"]], ["block_17", [{"image_3": "1031_3.png", "coords": [91, 348, 325, 366]}]], ["block_18", ["(b)\n"]], ["block_19", [{"image_4": "1031_4.png", "coords": [91, 382, 325, 402]}]], ["block_20", ["(c)\n"]], ["block_21", [{"image_5": "1031_5.png", "coords": [91, 418, 325, 438]}]], ["block_22", ["each isomer.\n"]], ["block_23", ["groups) of each isomer.\n"]], ["block_24", ["(a) dipropyl ether\n(b) 2,2-dimethyl-3-hexanol\n(c) 2-ethoxybutane\n"]], ["block_25", ["is manufactured by reacting 2-methylpropene with methanol.\n(a) Using Lewis structures, write the chemical equation representing the reaction.\n(b) What volume of methanol, density 0.7915 g/mL, is required to produce exactly 1000 kg of MTBE,\nassuming a 100% yield?\n"]], ["block_26", ["and one using Lewis structures.\n(a) propanol is converted to dipropyl ether\n(b) propene is treated with water in dilute acid.\n"]], ["block_27", ["and one using Lewis structures.\n(a) 2-butene is treated with water in dilute acid\n(b) ethanol is dehydrated to yield ethene\n"]]], "page_1032": [["block_0", [" 20.3 Aldehydes, Ketones, Carboxylic Acids, and Esters \n"]], ["block_1", [" 40 . Order the following molecules from least to most oxidized, based on the marked carbon atom:\n"]], ["block_2", [" 41 . Predict the products of oxidizing the molecules shown in this problem. In each case, identify the product\n"]], ["block_3", [" 42 . Predict the products of reducing the following molecules. In each case, identify the product that will result\n"]], ["block_4", [" 43 . Explain why it is not possible to prepare a ketone that contains only two carbon atoms.\n 44 . How does hybridization of the substituted carbon atom change when an alcohol is converted into an\n"]], ["block_5", [" 45 . Fatty acids are carboxylic acids that have long hydrocarbon chains attached to a carboxylate group. How\n"]], ["block_6", [" 46 . Write a condensed structural formula, such as CH3CH3, and describe the molecular geometry at each\n"]], ["block_7", [{"image_0": "1032_0.png", "coords": [91, 89, 442, 149]}]], ["block_8", ["that will result from the minimal increase in oxidation state for the highlighted carbon atom:\n(a)\n"]], ["block_9", [{"image_1": "1032_1.png", "coords": [91, 189, 316, 241]}]], ["block_10", ["(b)\n"]], ["block_11", [{"image_2": "1032_2.png", "coords": [91, 256, 316, 283]}]], ["block_12", ["(c)\n"]], ["block_13", [{"image_3": "1032_3.png", "coords": [91, 299, 316, 343]}]], ["block_14", ["from the minimal decrease in oxidation state for the highlighted carbon atom:\n(a)\n"]], ["block_15", [{"image_4": "1032_4.png", "coords": [91, 384, 316, 429]}]], ["block_16", ["(b)\n"]], ["block_17", [{"image_5": "1032_5.png", "coords": [91, 445, 316, 491]}]], ["block_18", ["(c)\n"]], ["block_19", [{"image_6": "1032_6.png", "coords": [91, 506, 316, 547]}]], ["block_20", ["aldehyde? An aldehyde to a carboxylic acid?\n"]], ["block_21", ["does a saturated fatty acid differ from an unsaturated fatty acid? How are they similar?\n"]], ["block_22", ["carbon atom.\n(a) propene\n(b) 1-butanol\n(c) ethyl propyl ether\n(d) cis-4-bromo-2-heptene\n(e) 2,2,3-trimethylhexane\n(f) formaldehyde\n"]], ["block_23", [" 20 \u2022 Exercises \n 1019 \n"]]], "page_1033": [["block_0", [" 1020 \n 20 \u2022 Exercises \n"]], ["block_1", [" 47 . Write a condensed structural formula, such as CH3CH3, and describe the molecular geometry at each\n"]], ["block_2", [" 48 . The foul odor of rancid butter is caused by butyric acid, CH3CH2CH2CO2H.\n"]], ["block_3", [" 49 . Write the two-resonance structures for the acetate ion.\n 50 . Write two complete, balanced equations for each of the following reactions, one using condensed formulas\n"]], ["block_4", [" 51 . Write two complete balanced equations for each of the following reactions, one using condensed formulas\n"]], ["block_5", [" 52 . Yields in organic reactions are sometimes low. What is the percent yield of a process that produces 13.0 g\n"]], ["block_6", [" 53 . Alcohols A, B, and C all have the composition C4H10O. Molecules of alcohol A contain a branched carbon\n"]], ["block_7", [" 20.4 Amines and Amides \n"]], ["block_8", [" 54 . Write the Lewis structures of both isomers with the formula C2H7N.\n 55 . What is the molecular structure about the nitrogen atom in trimethyl amine and in the trimethyl\n"]], ["block_9", [" 56 . Write the two resonance structures for the pyridinium ion, C5H5NH.\n 57 . Draw Lewis structures for pyridine and its conjugate acid, the pyridinium ion, C5H5NH. What are the\n"]], ["block_10", [" 58 . Write the Lewis structures of all isomers with the formula C3H7ON that contain an amide linkage.\n 59 . Write two complete balanced equations for the following reaction, one using condensed formulas and one\n"]], ["block_11", [" 60 . Write two complete, balanced equations for each of the following reactions, one using condensed formulas\n"]], ["block_12", [" 61 . Identify any carbon atoms that change hybridization and the change in hybridization during the reactions\n"]], ["block_13", [" 62 . Identify any carbon atoms that change hybridization and the change in hybridization during the reactions\n"]], ["block_14", [" 63 . Identify any carbon atoms that change hybridization and the change in hybridization during the reactions\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["carbon atom.\n(a) 2-propanol\n(b) acetone\n(c) dimethyl ether\n(d) acetic acid\n(e) 3-methyl-1-hexene\n"]], ["block_17", ["(a) Draw the Lewis structure and determine the oxidation number and hybridization for each carbon atom\nin the molecule.\n(b) The esters formed from butyric acid are pleasant-smelling compounds found in fruits and used in\nperfumes. Draw the Lewis structure for the ester formed from the reaction of butyric acid with\n2-propanol.\n"]], ["block_18", ["and one using Lewis structures:\n(a) ethanol reacts with propionic acid\n(b) benzoic acid, C6H5CO2H, is added to a solution of sodium hydroxide\n"]], ["block_19", ["and one using Lewis structures.\n(a) 1-butanol reacts with acetic acid\n(b) propionic acid is poured onto solid calcium carbonate\n"]], ["block_20", ["of ethyl acetate from 10.0 g of CH3CO2H?\n"]], ["block_21", ["chain and can be oxidized to an aldehyde; molecules of alcohol B contain a linear carbon chain and can be\noxidized to a ketone; and molecules of alcohol C can be oxidized to neither an aldehyde nor a ketone. Write\nthe Lewis structures of these molecules.\n"]], ["block_22", ["ammonium ion, (CH3)3NH? What is the hybridization of the nitrogen atom in trimethyl amine and in the\ntrimethyl ammonium ion?\n"]], ["block_23", ["hybridizations, electron domain geometries, and molecular geometries about the nitrogen atoms in\npyridine and in the pyridinium ion?\n"]], ["block_24", ["using Lewis structures.\nMethyl amine is added to a solution of HCl.\n"]], ["block_25", ["and one using Lewis structures.\nEthylammonium chloride is added to a solution of sodium hydroxide.\n"]], ["block_26", ["in Exercise 20.26.\n"]], ["block_27", ["in Exercise 20.39.\n"]], ["block_28", ["in Exercise 20.51.\n"]]], "page_1034": [["block_0", ["electronic structure of the species involved, that is, the arrangement of the electrons around atoms, ions, or\nmolecules. Nuclear structure, the numbers of protons and neutrons within the nuclei of the atoms involved,\nremains unchanged during chemical reactions.\n"]], ["block_1", ["CHAPTER 21\nNuclear Chemistry\n"]], ["block_2", [{"image_0": "1034_0.png", "coords": [72, 104, 622, 324]}]], ["block_3", [" Figure 21.1 \nNuclear chemistry provides the basis for many useful diagnostic and therapeutic methods in medicine,\n"]], ["block_4", ["such as these positron emission tomography (PET) scans. The PET/computed tomography scan on the left shows\nmuscle activity. The brain scans in the center show chemical differences in dopamine signaling in the brains of\naddicts and nonaddicts. The images on the right show an oncological application of PET scans to identify lymph\nnode metastasis.\n"]], ["block_5", [" CHAPTER OUTLINE \n"]], ["block_6", [" 21.1 Nuclear Structure and Stability \n 21.2 Nuclear Equations \n 21.3 Radioactive Decay \n 21.4 Transmutation and Nuclear Energy \n 21.5 Uses of Radioisotopes \n 21.6 Biological Effects of Radiation \n"]], ["block_7", [" INTRODUCTION \n"]], ["block_8", ["This chapter will introduce the topic of nuclear chemistry, which began with the discovery of radioactivity in\n1896 by French physicist Antoine Becquerel and has become increasingly important during the twentieth and\ntwenty-first centuries, providing the basis for various technologies related to energy, medicine, geology, and\nmany other areas.\n"]], ["block_9", ["The chemical reactions that we have considered in previous chapters involve changes in the\n"]]], "page_1035": [["block_0", [" 1022 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", [" 21.1 Nuclear Structure and Stability \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", [" Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The chapter on atoms,\nmolecules, and ions introduced the basic idea of nuclear structure, that the nucleus of an atom is composed of\nprotons and, with the exception of\nneutrons. Recall that the number of protons in the nucleus is called the\n"]], ["block_4", ["atomic number (Z) of the element, and the sum of the number of protons and the number of neutrons is the\nmass number (A). Atoms with the same atomic number but different mass numbers are isotopes of the same\nelement. When referring to a single type of nucleus, we often use the term nuclide and identify it by the\nnotation\nwhere X is the symbol for the element, A is the mass number, and Z is the atomic number (for\n"]], ["block_5", ["example,\nOften a nuclide is referenced by the name of the element followed by a hyphen and the mass\n"]], ["block_6", ["number. For example,\nis called \u201ccarbon-14.\u201d\n"]], ["block_7", ["Protons and neutrons, collectively called nucleons , are packed together tightly in a nucleus. With a radius of\nabout 10meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10\n"]], ["block_8", ["meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8\n10grams per cubic centimeter.\n"]], ["block_9", ["For example, water has a density of 1 gram per cubic centimeter, and iridium, one of the densest elements\nknown, has a density of 22.6 g/cm. If the earth\u2019s density were equal to the average nuclear density, the earth\u2019s\nradius would be only about 200 meters (earth\u2019s actual radius is approximately 6.4\n10meters, 30,000 times\n"]], ["block_10", ["larger). Example 21.1 demonstrates just how great nuclear densities can be in the natural world.\n"]], ["block_11", [" Density of a Neutron Star \n"]], ["block_12", ["Neutron stars form when the core of a very massive star undergoes gravitational collapse, causing the star\u2019s\nouter layers to explode in a supernova. Composed almost completely of neutrons, they are the densest-known\nstars in the universe, with densities comparable to the average density of an atomic nucleus. A neutron star in\na faraway galaxy has a mass equal to 2.4 solar masses (1 solar mass =\n= mass of the sun = 1.99\n10kg)\n"]], ["block_13", ["and a diameter of 26 km.\n"]], ["block_14", ["(a) What is the density of this neutron star?\n"]], ["block_15", ["(b) How does this neutron star\u2019s density compare to the density of a uranium nucleus, which has a diameter of\nabout 15 fm (1 fm = 10m)?\n"]], ["block_16", [" Solution \n"]], ["block_17", ["We can treat both the neutron star and the U-235 nucleus as spheres. Then the density for both is given by:\n"]], ["block_18", ["(a) The radius of the neutron star is\nso the density of the\n"]], ["block_19", ["neutron star is:\n"]], ["block_20", ["(b) The radius of the U-235 nucleus is\nso the density of the U-235\n"]], ["block_21", ["nucleus is:\n"]], ["block_22", [" Access for free at openstax.org \n"]], ["block_23", ["\u2022\nDescribe nuclear structure in terms of protons, neutrons, and electrons\n"]], ["block_24", ["\u2022\nCalculate mass defect and binding energy for nuclei\n"]], ["block_25", ["\u2022\nExplain trends in the relative stability of nuclei\n"]], ["block_26", ["EXAMPLE 21.1\n"]]], "page_1036": [["block_0", ["These values are fairly similar (same order of magnitude), but the neutron star is more than twice as dense as\nthe U-235 nucleus.\n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["Find the density of a neutron star with a mass of 1.97 solar masses and a diameter of 13 km, and compare it to\nthe density of a hydrogen nucleus, which has a diameter of 1.75 fm (1 fm = 1\n10m).\n"]], ["block_3", [" Answer: \nThe density of the neutron star is 3.4\n10kg/m. The density of a hydrogen nucleus is 6.0\n10kg/m. The\n"]], ["block_4", ["neutron star is 5.7 times denser than the hydrogen nucleus.\n"]], ["block_5", ["To hold positively charged protons together in the very small volume of a nucleus requires very strong\nattractive forces because the positively charged protons repel one another strongly at such short distances.\nThe force of attraction that holds the nucleus together is the strong nuclear force . (The strong force is one of\nthe four fundamental forces that are known to exist. The others are the electromagnetic force, the gravitational\nforce, and the nuclear weak force.) This force acts between protons, between neutrons, and between protons\nand neutrons. It is very different from the electrostatic force that holds negatively charged electrons around a\npositively charged nucleus (the attraction between opposite charges). Over distances less than 10meters\nand within the nucleus, the strong nuclear force is much stronger than electrostatic repulsions between\nprotons; over larger distances and outside the nucleus, it is essentially nonexistent.\n"]], ["block_6", ["Visit this website (http://openstax.org/l/16fourfund) for more information about the four fundamental forces.\n"]], ["block_7", [" Nuclear Binding Energy \n"]], ["block_8", ["As a simple example of the energy associated with the strong nuclear force, consider the helium atom\ncomposed of two protons, two neutrons, and two electrons. The total mass of these six subatomic particles may\nbe calculated as:\n"]], ["block_9", ["However, mass spectrometric measurements reveal that the mass of an\natom is 4.0026 amu, less than the\n"]], ["block_10", ["combined masses of its six constituent subatomic particles. This difference between the calculated and\nexperimentally measured masses is known as the mass defect of the atom. In the case of helium, the mass\ndefect indicates a \u201closs\u201d in mass of 4.0331 amu \u2013 4.0026 amu = 0.0305 amu. The loss in mass accompanying\nthe formation of an atom from protons, neutrons, and electrons is due to the conversion of that mass into\nenergy that is evolved as the atom forms. The nuclear binding energy is the energy produced when the atoms\u2019\nnucleons are bound together; this is also the energy needed to break a nucleus into its constituent protons and\nneutrons. In comparison to chemical bond energies, nuclear binding energies are vastly greater, as we will\nlearn in this section. Consequently, the energy changes associated with nuclear reactions are vastly greater\nthan are those for chemical reactions.\n"]], ["block_11", ["The conversion between mass and energy is most identifiably represented by the mass-energy equivalence \n equation as stated by Albert Einstein:\n"]], ["block_12", ["where E is energy, m is mass of the matter being converted, and c is the speed of light in a vacuum. This\nequation can be used to find the amount of energy that results when matter is converted into energy. Using this\n"]], ["block_13", ["LINK TO LEARNING\n"]], ["block_14", [" 21.1 \u2022 Nuclear Structure and Stability \n 1023 \n"]]], "page_1037": [["block_0", [" 1024 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", ["mass-energy equivalence equation, the nuclear binding energy of a nucleus may be calculated from its mass\ndefect, as demonstrated in Example 21.2. A variety of units are commonly used for nuclear binding energies,\nincluding electron volts (eV) , with 1 eV equaling the amount of energy necessary to the move the charge of an\nelectron across an electric potential difference of 1 volt, making 1 eV = 1.602\n10J.\n"]], ["block_2", [" Calculation of Nuclear Binding Energy \n"]], ["block_3", ["Determine the binding energy for the nuclide\nin:\n"]], ["block_4", ["(a) joules per mole of nuclei\n"]], ["block_5", ["(b) joules per nucleus\n"]], ["block_6", ["(c) MeV per nucleus\n"]], ["block_7", [" Solution \n"]], ["block_8", ["The mass defect for a\nnucleus is 0.0305 amu, as shown previously. Determine the binding energy in joules\n"]], ["block_9", ["per nuclide using the mass-energy equivalence equation. To accommodate the requested energy units, the\nmass defect must be expressed in kilograms (recall that 1 J = 1 kg m/s).\n"]], ["block_10", ["(a) First, express the mass defect in g/mol. This is easily done considering the numerical equivalence of atomic\nmass (amu) and molar mass (g/mol) that results from the definitions of the amu and mole units (refer to the\nprevious discussion in the chapter on atoms, molecules, and ions if needed). The mass defect is therefore\n0.0305 g/mol. To accommodate the units of the other terms in the mass-energy equation, the mass must be\nexpressed in kg, since 1 J = 1 kg m/s. Converting grams into kilograms yields a mass defect of 3.05\n10kg/\n"]], ["block_11", ["mol. Substituting this quantity into the mass-energy equivalence equation yields:\n"]], ["block_12", ["Note that this tremendous amount of energy is associated with the conversion of a very small amount of matter\n(about 30 mg, roughly the mass of typical drop of water).\n"]], ["block_13", ["(b) The binding energy for a single nucleus is computed from the molar binding energy using Avogadro\u2019s\nnumber:\n"]], ["block_14", ["(c) Recall that 1 eV = 1.602\n10J. Using the binding energy computed in part (b):\n"]], ["block_15", [" Check Your Learning \n"]], ["block_16", ["What is the binding energy for the nuclide\n(atomic mass: 18.9984 amu) in MeV per nucleus?\n"]], ["block_17", [" Answer: \n148.4 MeV\n"]], ["block_18", ["Because the energy changes for breaking and forming bonds are so small compared to the energy changes for\nbreaking or forming nuclei, the changes in mass during all ordinary chemical reactions are virtually\nundetectable. As described in the chapter on thermochemistry, the most energetic chemical reactions exhibit\n"]], ["block_19", [" Access for free at openstax.org \n"]], ["block_20", ["EXAMPLE 21.2\n"]]], "page_1038": [["block_0", ["enthalpies on the order of thousands of kJ/mol, which is equivalent to mass differences in the nanogram range\n(10g). On the other hand, nuclear binding energies are typically on the order of billions of kJ/mol,\ncorresponding to mass differences in the milligram range (10g).\n"]], ["block_1", [" Nuclear Stability \n"]], ["block_2", ["A nucleus is stable if it cannot be transformed into another configuration without adding energy from the\noutside. Of the thousands of nuclides that exist, about 250 are stable. A plot of the number of neutrons versus\nthe number of protons for stable nuclei reveals that the stable isotopes fall into a narrow band. This region is\nknown as the band of stability (also called the belt, zone, or valley of stability). The straight line in Figure 21.2\nrepresents nuclei that have a 1:1 ratio of protons to neutrons (n:p ratio). Note that the lighter stable nuclei, in\ngeneral, have equal numbers of protons and neutrons. For example, nitrogen-14 has seven protons and seven\nneutrons. Heavier stable nuclei, however, have increasingly more neutrons than protons. For example: iron-56\nhas 30 neutrons and 26 protons, an n:p ratio of 1.15, whereas the stable nuclide lead-207 has 125 neutrons\nand 82 protons, an n:p ratio equal to 1.52. This is because larger nuclei have more proton-proton repulsions,\nand require larger numbers of neutrons to provide compensating strong forces to overcome these electrostatic\nrepulsions and hold the nucleus together.\n"]], ["block_3", [" 21.1 \u2022 Nuclear Structure and Stability \n 1025 \n"]]], "page_1039": [["block_0", [" 1026 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", [{"image_0": "1039_0.png", "coords": [72, 57, 540, 561]}]], ["block_2", [" FIGURE 21.2 \nThis plot shows the nuclides that are known to exist and those that are stable. The stable nuclides\n"]], ["block_3", ["are indicated in blue, and the unstable nuclides are indicated in green. Note that all isotopes of elements with\natomic numbers greater than 83 are unstable. The solid line is the line where n = Z.\n"]], ["block_4", ["The nuclei that are to the left or to the right of the band of stability are unstable and exhibit radioactivity . They\nchange spontaneously (decay) into other nuclei that are either in, or closer to, the band of stability. These\nnuclear decay reactions convert one unstable isotope (or radioisotope ) into another, more stable, isotope. We\nwill discuss the nature and products of this radioactive decay in subsequent sections of this chapter.\n"]], ["block_5", ["Several observations may be made regarding the relationship between the stability of a nucleus and its\nstructure. Nuclei with even numbers of protons, neutrons, or both are more likely to be stable (see Table 21.1).\nNuclei with certain numbers of nucleons, known as magic numbers , are stable against nuclear decay. These\nnumbers of protons or neutrons (2, 8, 20, 28, 50, 82, and 126) make complete shells in the nucleus. These are\nsimilar in concept to the stable electron shells observed for the noble gases. Nuclei that have magic numbers of\n"]], ["block_6", [" Access for free at openstax.org \n"]]], "page_1040": [["block_0", ["both protons and neutrons, such as\nand\nare called \u201cdouble magic\u201d and are particularly\n"]], ["block_1", ["stable. These trends in nuclear stability may be rationalized by considering a quantum mechanical model of\nnuclear energy states analogous to that used to describe electronic states earlier in this textbook. The details of\nthis model are beyond the scope of this chapter.\n"]], ["block_2", ["The relative stability of a nucleus is correlated with its binding energy per nucleon , the total binding energy\nfor the nucleus divided by the number or nucleons in the nucleus. For instance, we saw in Example 21.2 that\nthe binding energy for a\nnucleus is 28.4 MeV. The binding energy per nucleon for a\nnucleus is\n"]], ["block_3", ["therefore:\n"]], ["block_4", ["In Example 21.3, we learn how to calculate the binding energy per nucleon of a nuclide on the curve shown in\nFigure 21.3.\n"]], ["block_5", [" FIGURE 21.3 \nThe binding energy per nucleon is largest for nuclides with mass number of approximately 56.\n"]], ["block_6", [{"image_0": "1040_0.png", "coords": [130, 422, 481, 707]}]], ["block_7", [" TABLE 21.1 \n"]], ["block_8", [" Number of Stable Isotopes \n Proton Number \n Neutron Number \n"]], ["block_9", ["157\neven\neven\n"]], ["block_10", ["53\neven\nodd\n"]], ["block_11", ["50\nodd\neven\n"]], ["block_12", ["5\nodd\nodd\n"]], ["block_13", ["Stable Nuclear Isotopes\n"]], ["block_14", [" 21.1 \u2022 Nuclear Structure and Stability \n 1027 \n"]]], "page_1041": [["block_0", [" 1028 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", [" Calculation of Binding Energy per Nucleon \n"]], ["block_2", ["The iron nuclide\nlies near the top of the binding energy curve (Figure 21.3) and is one of the most stable\n"]], ["block_3", ["nuclides. What is the binding energy per nucleon (in MeV) for the nuclide\n(atomic mass of 55.9349 amu)?\n"]], ["block_4", [" Solution \n"]], ["block_5", ["As in Example 21.2, we first determine the mass defect of the nuclide, which is the difference between the\nmass of 26 protons, 30 neutrons, and 26 electrons, and the observed mass of an\natom:\n"]], ["block_6", ["We next calculate the binding energy for one nucleus from the mass defect using the mass-energy equivalence\nequation:\n"]], ["block_7", ["We then convert the binding energy in joules per nucleus into units of MeV per nuclide:\n"]], ["block_8", ["Finally, we determine the binding energy per nucleon by dividing the total nuclear binding energy by the\nnumber of nucleons in the atom:\n"]], ["block_9", ["Note that this is almost 25% larger than the binding energy per nucleon for\n"]], ["block_10", ["(Note also that this is the same process as in Example 21.1, but with the additional step of dividing the total\nnuclear binding energy by the number of nucleons.)\n"]], ["block_11", [" Check Your Learning \n"]], ["block_12", ["What is the binding energy per nucleon in\n(atomic mass, 18.9984 amu)?\n"]], ["block_13", [" Answer: \n7.810 MeV/nucleon\n"]], ["block_14", [" 21.2 Nuclear Equations \n"]], ["block_15", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_16", ["Changes of nuclei that result in changes in their atomic numbers, mass numbers, or energy states are nuclear \n reactions . To describe a nuclear reaction, we use an equation that identifies the nuclides involved in the\nreaction, their mass numbers and atomic numbers, and the other particles involved in the reaction.\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["\u2022\nIdentify common particles and energies involved in nuclear reactions\n"]], ["block_19", ["\u2022\nWrite and balance nuclear equations\n"]], ["block_20", ["EXAMPLE 21.3\n"]]], "page_1042": [["block_0", [" Types of Particles in Nuclear Reactions \n"]], ["block_1", ["Many entities can be involved in nuclear reactions. The most common are protons, neutrons, alpha particles,\nbeta particles, positrons, and gamma rays, as shown in Figure 21.4. Protons\nalso represented by the\n"]], ["block_2", ["symbol\nand neutrons\nare the constituents of atomic nuclei, and have been described previously.\n"]], ["block_3", [" Alpha particles \nalso represented by the symbol\nare high-energy helium nuclei. Beta particles \n"]], ["block_4", ["high-energy electromagnetic radiation. Positrons \nalso represented by the symbol\nare positively\n"]], ["block_5", ["charged electrons (\u201canti-electrons\u201d). The subscripts and superscripts are necessary for balancing nuclear\nequations, but are usually optional in other circumstances. For example, an alpha particle is a helium nucleus\n(He) with a charge of +2 and a mass number of 4, so it is symbolized\nThis works because, in general, the\n"]], ["block_6", ["ion charge is not important in the balancing of nuclear equations.\n"]], ["block_7", [{"image_0": "1042_0.png", "coords": [72, 220, 540, 472]}]], ["block_8", [" FIGURE 21.4 \nAlthough many species are encountered in nuclear reactions, this table summarizes the names,\n"]], ["block_9", ["symbols, representations, and descriptions of the most common of these.\n"]], ["block_10", ["Note that positrons are exactly like electrons, except they have the opposite charge. They are the most common\nexample of antimatter , particles with the same mass but the opposite state of another property (for example,\ncharge) than ordinary matter. When antimatter encounters ordinary matter, both are annihilated and their\nmass is converted into energy in the form of gamma rays ( \u03b3 ) \u2014and other much smaller subnuclear particles,\nwhich are beyond the scope of this chapter\u2014according to the mass-energy equivalence equation E = mc, seen\nin the preceding section. For example, when a positron and an electron collide, both are annihilated and two\ngamma ray photons are created:\n"]], ["block_11", ["As seen in the chapter discussing light and electromagnetic radiation, gamma rays compose short wavelength,\nhigh-energy electromagnetic radiation and are (much) more energetic than better-known X-rays that can\nbehave as particles in the wave-particle duality sense. Gamma rays are a type of high energy electromagnetic\nradiation produced when a nucleus undergoes a transition from a higher to a lower energy state, similar to\nhow a photon is produced by an electronic transition from a higher to a lower energy level. Due to the much\nlarger energy differences between nuclear energy shells, gamma rays emanating from a nucleus have energies\nthat are typically millions of times larger than electromagnetic radiation emanating from electronic\ntransitions.\n"]], ["block_12", ["also represented by the symbol\nare high-energy electrons, and gamma rays are photons of very\n"]], ["block_13", [" 21.2 \u2022 Nuclear Equations \n 1029 \n"]]], "page_1043": [["block_0", [" 1030 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", [" Balancing Nuclear Reactions \n"]], ["block_2", ["A balanced chemical reaction equation reflects the fact that during a chemical reaction, bonds break and form,\nand atoms are rearranged, but the total numbers of atoms of each element are conserved and do not change. A\nbalanced nuclear reaction equation indicates that there is a rearrangement during a nuclear reaction, but of\nnucleons (subatomic particles within the atoms\u2019 nuclei) rather than atoms. Nuclear reactions also follow\nconservation laws, and they are balanced in two ways:\n"]], ["block_3", ["If the atomic number and the mass number of all but one of the particles in a nuclear reaction are known, we\ncan identify the particle by balancing the reaction. For instance, we could determine that\nis a product of\n"]], ["block_4", ["the nuclear reaction of\nand\nif we knew that a proton,\nwas one of the two products. Example 21.4\n"]], ["block_5", ["shows how we can identify a nuclide by balancing the nuclear reaction.\n"]], ["block_6", [" Balancing Equations for Nuclear Reactions \n"]], ["block_7", ["The reaction of an \u03b1 particle with magnesium-25\nproduces a proton and a nuclide of another element.\n"]], ["block_8", ["Identify the new nuclide produced.\n"]], ["block_9", [" Solution \n"]], ["block_10", ["The nuclear reaction can be written as:\n"]], ["block_11", ["where A is the mass number and Z is the atomic number of the new nuclide, X. Because the sum of the mass\nnumbers of the reactants must equal the sum of the mass numbers of the products:\n"]], ["block_12", ["Similarly, the charges must balance, so:\n"]], ["block_13", ["Check the periodic table: The element with nuclear charge = +13 is aluminum. Thus, the product is\n"]], ["block_14", [" Check Your Learning \n"]], ["block_15", ["The nuclide\ncombines with an electron and produces a new nucleus and no other massive particles. What\n"]], ["block_16", ["is the equation for this reaction?\n"]], ["block_17", [" Answer: \n"]], ["block_18", ["Following are the equations of several nuclear reactions that have important roles in the history of nuclear\nchemistry:\n"]], ["block_19", [" Access for free at openstax.org \n"]], ["block_20", ["1.\nThe sum of the mass numbers of the reactants equals the sum of the mass numbers of the products.\n"]], ["block_21", ["2.\nThe sum of the charges of the reactants equals the sum of the charges of the products.\n"]], ["block_22", ["\u2022\nThe first naturally occurring unstable element that was isolated, polonium, was discovered by the Polish\nscientist Marie Curie and her husband Pierre in 1898. It decays, emitting \u03b1 particles:\n"]], ["block_23", ["\u2022\nThe first nuclide to be prepared by artificial means was an isotope of oxygen, O. It was made by Ernest\nRutherford in 1919 by bombarding nitrogen atoms with \u03b1 particles:\n"]], ["block_24", ["\u2022\nJames Chadwick discovered the neutron in 1932, as a previously unknown neutral particle produced\nalong with C by the nuclear reaction between Be and He:\n"]], ["block_25", ["EXAMPLE 21.4\n"]]], "page_1044": [["block_0", [" 21.3 Radioactive Decay \n"]], ["block_1", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_2", ["Following the somewhat serendipitous discovery of radioactivity by Becquerel, many prominent scientists\nbegan to investigate this new, intriguing phenomenon. Among them were Marie Curie (the first woman to win a\nNobel Prize, and the only person to win two Nobel Prizes in different sciences\u2014chemistry and physics), who\nwas the first to coin the term \u201cradioactivity,\u201d and Ernest Rutherford (of gold foil experiment fame), who\ninvestigated and named three of the most common types of radiation. During the beginning of the twentieth\ncentury, many radioactive substances were discovered, the properties of radiation were investigated and\nquantified, and a solid understanding of radiation and nuclear decay was developed.\n"]], ["block_3", ["The spontaneous change of an unstable nuclide into another is radioactive decay . The unstable nuclide is\ncalled the parent nuclide ; the nuclide that results from the decay is known as the daughter nuclide . The\ndaughter nuclide may be stable, or it may decay itself. The radiation produced during radioactive decay is such\nthat the daughter nuclide lies closer to the band of stability than the parent nuclide, so the location of a nuclide\nrelative to the band of stability can serve as a guide to the kind of decay it will undergo (Figure 21.5).\n"]], ["block_4", [" FIGURE 21.5 \nA nucleus of uranium-238 (the parent nuclide) undergoes \u03b1 decay to form thorium-234 (the\n"]], ["block_5", ["daughter nuclide). The alpha particle removes two protons (green) and two neutrons (gray) from the uranium-238\nnucleus.\n"]], ["block_6", ["Although the radioactive decay of a nucleus is too small to see with the naked eye, we can indirectly view\nradioactive decay in an environment called a cloud chamber. Click here (http://openstax.org/l/16cloudchamb)\nto learn about cloud chambers and to view an interesting Cloud Chamber Demonstration from the Jefferson\nLab.\n"]], ["block_7", ["\u2022\nThe first element to be prepared that does not occur naturally on the earth, technetium, was created by\nbombardment of molybdenum by deuterons (heavy hydrogen,\n, by Emilio Segre and Carlo Perrier in\n"]], ["block_8", ["\u2022\nThe first controlled nuclear chain reaction was carried out in a reactor at the University of Chicago in\n1942. One of the many reactions involved was:\n"]], ["block_9", ["\u2022\nRecognize common modes of radioactive decay\n"]], ["block_10", ["\u2022\nIdentify common particles and energies involved in nuclear decay reactions\n"]], ["block_11", ["\u2022\nWrite and balance nuclear decay equations\n"]], ["block_12", ["\u2022\nCalculate kinetic parameters for decay processes, including half-life\n"]], ["block_13", ["\u2022\nDescribe common radiometric dating techniques\n"]], ["block_14", ["1937:\n"]], ["block_15", ["LINK TO LEARNING\n"]], ["block_16", [{"image_0": "1044_0.png", "coords": [130, 469, 481, 594]}]], ["block_17", [" 21.3 \u2022 Radioactive Decay \n 1031 \n"]]], "page_1045": [["block_0", [" 1032 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", [" Types of Radioactive Decay \n"]], ["block_2", ["Ernest Rutherford\u2019s experiments involving the interaction of radiation with a magnetic or electric field (Figure\n21.6) helped him determine that one type of radiation consisted of positively charged and relatively massive \u03b1\nparticles; a second type was made up of negatively charged and much less massive \u03b2 particles; and a third was\nuncharged electromagnetic waves, \u03b3 rays. We now know that \u03b1 particles are high-energy helium nuclei, \u03b2\nparticles are high-energy electrons, and \u03b3 radiation compose high-energy electromagnetic radiation. We\nclassify different types of radioactive decay by the radiation produced.\n"]], ["block_3", [" FIGURE 21.6 \nAlpha particles, which are attracted to the negative plate and deflected by a relatively small amount,\n"]], ["block_4", ["must be positively charged and relatively massive. Beta particles, which are attracted to the positive plate and\ndeflected a relatively large amount, must be negatively charged and relatively light. Gamma rays, which are\nunaffected by the electric field, must be uncharged.\n"]], ["block_5", [" Alpha ( \u03b1 ) decay is the emission of an \u03b1 particle from the nucleus. For example, polonium-210 undergoes \u03b1\ndecay:\n"]], ["block_6", ["Alpha decay occurs primarily in heavy nuclei (A > 200, Z > 83). Because the loss of an \u03b1 particle gives a\ndaughter nuclide with a mass number four units smaller and an atomic number two units smaller than those\nof the parent nuclide, the daughter nuclide has a larger n:p ratio than the parent nuclide. If the parent nuclide\nundergoing \u03b1 decay lies below the band of stability (refer to Figure 21.2), the daughter nuclide will lie closer to\nthe band.\n"]], ["block_7", [" Beta ( \u03b2 ) decay is the emission of an electron from a nucleus. Iodine-131 is an example of a nuclide that\nundergoes \u03b2 decay:\n"]], ["block_8", ["Beta decay, which can be thought of as the conversion of a neutron into a proton and a \u03b2 particle, is observed in\nnuclides with a large n:p ratio. The beta particle (electron) emitted is from the atomic nucleus and is not one of\nthe electrons surrounding the nucleus. Such nuclei lie above the band of stability. Emission of an electron does\nnot change the mass number of the nuclide but does increase the number of its protons and decrease the\nnumber of its neutrons. Consequently, the n:p ratio is decreased, and the daughter nuclide lies closer to the\nband of stability than did the parent nuclide.\n"]], ["block_9", [" Gamma emission ( \u03b3 emission) is observed when a nuclide is formed in an excited state and then decays to its\nground state with the emission of a \u03b3 ray, a quantum of high-energy electromagnetic radiation. The presence\nof a nucleus in an excited state is often indicated by an asterisk (*). Cobalt-60 emits \u03b3 radiation and is used in\nmany applications including cancer treatment:\n"]], ["block_10", ["There is no change in mass number or atomic number during the emission of a \u03b3 ray unless the \u03b3 emission\naccompanies one of the other modes of decay.\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", [{"image_0": "1045_0.png", "coords": [130, 159, 481, 313]}]]], "page_1046": [["block_0", [" Positron emission ( \u03b2 + decay ) is the emission of a positron from the nucleus. Oxygen-15 is an example of a\nnuclide that undergoes positron emission:\n"]], ["block_1", ["Positron emission is observed for nuclides in which the n:p ratio is low. These nuclides lie below the band of\nstability. Positron decay is the conversion of a proton into a neutron with the emission of a positron. The n:p\nratio increases, and the daughter nuclide lies closer to the band of stability than did the parent nuclide.\n"]], ["block_2", [" Electron capture occurs when one of the inner electrons in an atom is captured by the atom\u2019s nucleus. For\nexample, potassium-40 undergoes electron capture:\n"]], ["block_3", ["Electron capture occurs when an inner shell electron combines with a proton and is converted into a neutron.\nThe loss of an inner shell electron leaves a vacancy that will be filled by one of the outer electrons. As the outer\nelectron drops into the vacancy, it will emit energy. In most cases, the energy emitted will be in the form of an\nX-ray. Like positron emission, electron capture occurs for \u201cproton-rich\u201d nuclei that lie below the band of\nstability. Electron capture has the same effect on the nucleus as does positron emission: The atomic number is\ndecreased by one and the mass number does not change. This increases the n:p ratio, and the daughter\nnuclide lies closer to the band of stability than did the parent nuclide. Whether electron capture or positron\nemission occurs is difficult to predict. The choice is primarily due to kinetic factors, with the one requiring the\nsmaller activation energy being the one more likely to occur.\n"]], ["block_4", ["Figure 21.7 summarizes these types of decay, along with their equations and changes in atomic and mass\nnumbers.\n"]], ["block_5", [{"image_0": "1046_0.png", "coords": [72, 358, 540, 669]}]], ["block_6", [" FIGURE 21.7 \nThis table summarizes the type, nuclear equation, representation, and any changes in the mass or\n"]], ["block_7", ["atomic numbers for various types of decay.\n"]], ["block_8", [" 21.3 \u2022 Radioactive Decay \n 1033 \n"]]], "page_1047": [["block_0", [" 1034 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", [" Radioactive Decay Series \n"]], ["block_2", ["The naturally occurring radioactive isotopes of the heaviest elements fall into chains of successive\ndisintegrations, or decays, and all the species in one chain constitute a radioactive family, or radioactive \n decay series . Three of these series include most of the naturally radioactive elements of the periodic table.\nThey are the uranium series, the actinide series, and the thorium series. The neptunium series is a fourth\nseries, which is no longer significant on the earth because of the short half-lives of the species involved. Each\nseries is characterized by a parent (first member) that has a long half-life and a series of daughter nuclides that\nultimately lead to a stable end-product\u2014that is, a nuclide on the band of stability (Figure 21.9). In all three\nseries, the end-product is a stable isotope of lead. The neptunium series, previously thought to terminate with\nbismuth-209, terminates with thallium-205.\n"]], ["block_3", [" Access for free at openstax.org \n"]], ["block_4", ["Chemistry in Everyday Life\n"]], ["block_5", [" PET Scan \nPositron emission tomography (PET) scans use radiation to diagnose and track health conditions and\nmonitor medical treatments by revealing how parts of a patient\u2019s body function (Figure 21.8). To perform a\nPET scan, a positron-emitting radioisotope is produced in a cyclotron and then attached to a substance that\nis used by the part of the body being investigated. This \u201ctagged\u201d compound, or radiotracer, is then put into\nthe patient (injected via IV or breathed in as a gas), and how it is used by the tissue reveals how that organ\nor other area of the body functions.\n"]], ["block_6", [" FIGURE 21.8 \nA PET scanner (a) uses radiation to provide an image of how part of a patient\u2019s body functions.\n"]], ["block_7", ["The scans it produces can be used to image a healthy brain (b) or can be used for diagnosing medical conditions\nsuch as Alzheimer\u2019s disease (c). (credit a: modification of work by Jens Maus)\n"]], ["block_8", ["For example, F-18 is produced by proton bombardment of O\nand incorporated\n"]], ["block_9", ["into a glucose analog called fludeoxyglucose (FDG). How FDG is used by the body provides critical\ndiagnostic information; for example, since cancers use glucose differently than normal tissues, FDG can\nreveal cancers. The F emits positrons that interact with nearby electrons, producing a burst of gamma\nradiation. This energy is detected by the scanner and converted into a detailed, three-dimensional, color\nimage that shows how that part of the patient\u2019s body functions. Different levels of gamma radiation produce\ndifferent amounts of brightness and colors in the image, which can then be interpreted by a radiologist to\nreveal what is going on. PET scans can detect heart damage and heart disease, help diagnose Alzheimer\u2019s\ndisease, indicate the part of a brain that is affected by epilepsy, reveal cancer, show what stage it is, and\nhow much it has spread, and whether treatments are effective. Unlike magnetic resonance imaging and X-\nrays, which only show how something looks, the big advantage of PET scans is that they show how\nsomething functions. PET scans are now usually performed in conjunction with a computed tomography\nscan.\n"]], ["block_10", [{"image_0": "1047_0.png", "coords": [130, 180, 481, 300]}]]], "page_1048": [["block_0", [{"image_0": "1048_0.png", "coords": [72, 57, 540, 365]}]], ["block_1", [" FIGURE 21.9 \nUranium-238 undergoes a radioactive decay series consisting of 14 separate steps before producing\n"]], ["block_2", ["stable lead-206. This series consists of eight \u03b1 decays and six \u03b2 decays.\n"]], ["block_3", [" Radioactive Half-Lives \n"]], ["block_4", ["Radioactive decay follows first-order kinetics. Since first-order reactions have already been covered in detail in\nthe kinetics chapter, we will now apply those concepts to nuclear decay reactions. Each radioactive nuclide has\na characteristic, constant half-life (t1/2), the time required for half of the atoms in a sample to decay. An\nisotope\u2019s half-life allows us to determine how long a sample of a useful isotope will be available, and how long a\nsample of an undesirable or dangerous isotope must be stored before it decays to a low-enough radiation level\nthat is no longer a problem.\n"]], ["block_5", ["For example, cobalt-60, an isotope that emits gamma rays used to treat cancer, has a half-life of 5.27 years\n(Figure 21.10). In a given cobalt-60 source, since half of the\nnuclei decay every 5.27 years, both the\n"]], ["block_6", ["amount of material and the intensity of the radiation emitted is cut in half every 5.27 years. (Note that for a\ngiven substance, the intensity of radiation that it produces is directly proportional to the rate of decay of the\nsubstance and the amount of the substance.) This is as expected for a process following first-order kinetics.\nThus, a cobalt-60 source that is used for cancer treatment must be replaced regularly to continue to be\neffective.\n"]], ["block_7", [" 21.3 \u2022 Radioactive Decay \n 1035 \n"]]], "page_1049": [["block_0", [" 1036 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", [" FIGURE 21.10 \nFor cobalt-60, which has a half-life of 5.27 years, 50% remains after 5.27 years (one half-life), 25%\n"]], ["block_2", ["remains after 10.54 years (two half-lives), 12.5% remains after 15.81 years (three half-lives), and so on.\n"]], ["block_3", ["Since nuclear decay follows first-order kinetics, we can adapt the mathematical relationships used for first-\norder chemical reactions. We generally substitute the number of nuclei, N, for the concentration. If the rate is\nstated in nuclear decays per second, we refer to it as the activity of the radioactive sample. The rate for\nradioactive decay is:\n"]], ["block_4", ["decay rate = \u03bbN with \u03bb = the decay constant for the particular radioisotope\n"]], ["block_5", ["The decay constant, \u03bb, which is the same as a rate constant discussed in the kinetics chapter. It is possible to\nexpress the decay constant in terms of the half-life, t1/2:\n"]], ["block_6", ["The first-order equations relating amount, N, and time are:\n"]], ["block_7", ["where N0 is the initial number of nuclei or moles of the isotope, and Nt is the number of nuclei/moles\nremaining at time t. Example 21.5 applies these calculations to find the rates of radioactive decay for specific\nnuclides.\n"]], ["block_8", [" Rates of Radioactive Decay \n"]], ["block_9", ["(a) What is the decay constant for the radioactive disintegration of cobalt-60?\n"]], ["block_10", ["(b) Calculate the fraction of a sample of the\nisotope that will remain after 15 years.\n"]], ["block_11", ["(c) How long does it take for a sample of\nto disintegrate to the extent that only 2.0% of the original amount\n"]], ["block_12", ["remains?\n"]], ["block_13", [" Solution \n"]], ["block_14", ["(a) The value of the rate constant is given by:\n"]], ["block_15", [" Access for free at openstax.org \n"]], ["block_16", ["decays with a half-life of 5.27 years to produce\n"]], ["block_17", ["EXAMPLE 21.5\n"]], ["block_18", [{"image_0": "1049_0.png", "coords": [130, 57, 481, 271]}]]], "page_1050": [["block_0", ["N0eto solve for this ratio yields:\n"]], ["block_1", ["(b) The fraction of\nthat is left after time t is given by\nRearranging the first-order relationship Nt =\n"]], ["block_2", ["The fraction of\nthat will remain after 15.0 years is 0.138. Or put another way, 13.8% of the\noriginally\n"]], ["block_3", ["present will remain after 15 years.\n"]], ["block_4", ["(c) 2.00% of the original amount of\nis equal to 0.0200\nN0. Substituting this into the equation for time for\n"]], ["block_5", ["first-order kinetics, we have:\n"]], ["block_6", [" Check Your Learning \n"]], ["block_7", ["Radon-222,\nhas a half-life of 3.823 days. How long will it take a sample of radon-222 with a mass of\n"]], ["block_8", ["0.750 g to decay into other elements, leaving only 0.100 g of radon-222?\n"]], ["block_9", [" Answer: \n11.1 days\n"]], ["block_10", ["Because each nuclide has a specific number of nucleons, a particular balance of repulsion and attraction, and\nits own degree of stability, the half-lives of radioactive nuclides vary widely. For example: the half-life of\n"]], ["block_11", ["is 1.9\n10years;\nis 24,000 years;\nis 3.82 days; and element-111 (Rg for roentgenium) is 1.5\n"]], ["block_12", ["10seconds. The half-lives of a number of radioactive isotopes important to medicine are shown in Table\n21.2, and others are listed in Appendix M.\n"]], ["block_13", [" Radiometric Dating \n"]], ["block_14", ["Several radioisotopes have half-lives and other properties that make them useful for purposes of \u201cdating\u201d the\norigin of objects such as archaeological artifacts, formerly living organisms, or geological formations. This\nprocess is radiometric dating and has been responsible for many breakthrough scientific discoveries about\n"]], ["block_15", ["1 The \u201cm\u201d in Tc-99m stands for \u201cmetastable,\u201d indicating that this is an unstable, high-energy state of Tc-99. Metastable isotopes\nemit \u03b3 radiation to rid themselves of excess energy and become (more) stable.\n"]], ["block_16", [" TABLE 21.2 \n"]], ["block_17", [" Type 1 \n Decay Mode \n Half-Life \n Uses \n"]], ["block_18", ["F-18\n\u03b2decay\n110. minutes\nPET scans\n"]], ["block_19", ["Co-60\n\u03b2 decay, \u03b3 decay\n5.27 years\ncancer treatment\n"]], ["block_20", ["Tc-99m\n\u03b3 decay\n8.01 hours\nscans of brain, lung, heart, bone\n"]], ["block_21", ["I-131\n\u03b2 decay\n8.02 days\nthyroid scans and treatment\n"]], ["block_22", ["Tl-201\nelectron capture\n73 hours\nheart and arteries scans; cardiac stress tests\n"]], ["block_23", ["Half-lives of Radioactive Isotopes Important to Medicine\n"]], ["block_24", [" 21.3 \u2022 Radioactive Decay \n 1037 \n"]]], "page_1051": [["block_0", [" 1038 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", ["the geological history of the earth, the evolution of life, and the history of human civilization. We will explore\nsome of the most common types of radioactive dating and how the particular isotopes work for each type.\n"]], ["block_2", [" Radioactive Dating Using Carbon-14 \nThe radioactivity of carbon-14 provides a method for dating objects that were a part of a living organism. This\nmethod of radiometric dating, which is also called radiocarbon dating or carbon-14 dating, is accurate for\ndating carbon-containing substances that are up to about 30,000 years old, and can provide reasonably\naccurate dates up to a maximum of about 50,000 years old.\n"]], ["block_3", ["Naturally occurring carbon consists of three isotopes:\nwhich constitutes about 99% of the carbon on\n"]], ["block_4", ["earth;\nabout 1% of the total; and trace amounts of\nCarbon-14 forms in the upper atmosphere by the\n"]], ["block_5", ["reaction of nitrogen atoms with neutrons from cosmic rays in space:\n"]], ["block_6", ["All isotopes of carbon react with oxygen to produce CO2 molecules. The ratio of\nto\ndepends on\n"]], ["block_7", ["the ratio of\nto\nin the atmosphere. The natural abundance of\nin the atmosphere is\n"]], ["block_8", ["approximately 1 part per trillion; until recently, this has generally been constant over time, as seen is gas\nsamples found trapped in ice. The incorporation of\nand\ninto plants is a regular part of the\n"]], ["block_9", ["photosynthesis process, which means that the\nratio found in a living plant is the same as the\n"]], ["block_10", ["Because\nis a stable isotope and does not undergo radioactive decay, its concentration in the plant does not\n"]], ["block_11", ["change. However, carbon-14 decays by \u03b2 emission with a half-life of 5730 years:\n"]], ["block_12", ["Thus, the\nratio gradually decreases after the plant dies. The decrease in the ratio with time provides\n"]], ["block_13", ["a measure of the time that has elapsed since the death of the plant (or other organism that ate the plant).\nFigure 21.11 visually depicts this process.\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["ratio in the atmosphere. But when the plant dies, it no longer traps carbon through photosynthesis.\n"]]], "page_1052": [["block_0", [" FIGURE 21.11 \nAlong with stable carbon-12, radioactive carbon-14 is taken in by plants and animals, and remains\n"]], ["block_1", ["at a constant level within them while they are alive. After death, the C-14 decays and the C-14:C-12 ratio in the\nremains decreases. Comparing this ratio to the C-14:C-12 ratio in living organisms allows us to determine how long\nago the organism lived (and died).\n"]], ["block_2", ["For example, with the half-life of\nbeing 5730 years, if the\nratio in a wooden object found in an\n"]], ["block_3", ["archaeological dig is half what it is in a living tree, this indicates that the wooden object is 5730 years old.\nHighly accurate determinations of\nratios can be obtained from very small samples (as little as a\n"]], ["block_4", ["milligram) by the use of a mass spectrometer.\n"]], ["block_5", ["Visit this website (http://openstax.org/l/16phetradiom) to perform simulations of radiometric dating.\n"]], ["block_6", [" Radiocarbon Dating \n"]], ["block_7", ["A tiny piece of paper (produced from formerly living plant matter) taken from the Dead Sea Scrolls has an\nactivity of 10.8 disintegrations per minute per gram of carbon. If the initial C-14 activity was 13.6\ndisintegrations/min/g of C, estimate the age of the Dead Sea Scrolls.\n"]], ["block_8", [" Solution \n"]], ["block_9", ["The rate of decay (number of disintegrations/minute/gram of carbon) is proportional to the amount of\nradioactive C-14 left in the paper, so we can substitute the rates for the amounts, N, in the relationship:\n"]], ["block_10", ["LINK TO LEARNING\n"]], ["block_11", ["EXAMPLE 21.6\n"]], ["block_12", [{"image_0": "1052_0.png", "coords": [130, 57, 481, 380]}]], ["block_13", [" 21.3 \u2022 Radioactive Decay \n 1039 \n"]]], "page_1053": [["block_0", [" 1040 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", ["where the subscript 0 represents the time when the plants were cut to make the paper, and the subscript t\nrepresents the current time.\n"]], ["block_2", ["The decay constant can be determined from the half-life of C-14, 5730 years:\n"]], ["block_3", ["Substituting and solving, we have:\n"]], ["block_4", ["Therefore, the Dead Sea Scrolls are approximately 1900 years old (Figure 21.12).\n"]], ["block_5", [" FIGURE 21.12 \nCarbon-14 dating has shown that these pages from the Dead Sea Scrolls were written or copied on\n"]], ["block_6", ["paper made from plants that died between 100 BC and AD 50.\n"]], ["block_7", [" Check Your Learning \n"]], ["block_8", ["More accurate dates of the reigns of ancient Egyptian pharaohs have been determined recently using plants\nthat were preserved in their tombs. Samples of seeds and plant matter from King Tutankhamun\u2019s tomb have a\nC-14 decay rate of 9.07 disintegrations/min/g of C. How long ago did King Tut\u2019s reign come to an end?\n"]], ["block_9", [" Answer: \nabout 3350 years ago, or approximately 1340 BC\n"]], ["block_10", ["There have been some significant, well-documented changes to the\nratio. The accuracy of a\n"]], ["block_11", ["straightforward application of this technique depends on the\nratio in a living plant being the same\n"]], ["block_12", ["now as it was in an earlier era, but this is not always valid. Due to the increasing accumulation of CO2\nmolecules (largely\nin the atmosphere caused by combustion of fossil fuels (in which essentially all of\n"]], ["block_13", ["the\nhas decayed), the ratio of\nin the atmosphere may be changing. This manmade increase in\n"]], ["block_14", ["living organisms on the earth. Fortunately, however, we can use other data, such as tree dating via examination\nof annual growth rings, to calculate correction factors. With these correction factors, accurate dates can be\ndetermined. In general, radioactive dating only works for about 10 half-lives; therefore, the limit for carbon-14\ndating is about 57,000 years.\n"]], ["block_15", [" Radioactive Dating Using Nuclides Other than Carbon-14 \nRadioactive dating can also use other radioactive nuclides with longer half-lives to date older events. For\nexample, uranium-238 (which decays in a series of steps into lead-206) can be used for establishing the age of\nrocks (and the approximate age of the oldest rocks on earth). Since U-238 has a half-life of 4.5 billion years, it\ntakes that amount of time for half of the original U-238 to decay into Pb-206. In a sample of rock that does not\ncontain appreciable amounts of Pb-208, the most abundant isotope of lead, we can assume that lead was not\npresent when the rock was formed. Therefore, by measuring and analyzing the ratio of U-238:Pb-206, we can\ndetermine the age of the rock. This assumes that all of the lead-206 present came from the decay of\nuranium-238. If there is additional lead-206 present, which is indicated by the presence of other lead isotopes\nin the sample, it is necessary to make an adjustment. Potassium-argon dating uses a similar method. K-40\ndecays by positron emission and electron capture to form Ar-40 with a half-life of 1.25 billion years. If a rock\nsample is crushed and the amount of Ar-40 gas that escapes is measured, determination of the Ar-40:K-40\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["in the atmosphere causes the\nratio to decrease, and this in turn affects the ratio in currently\n"]], ["block_18", [{"image_0": "1053_0.png", "coords": [126, 210, 486, 295]}]]], "page_1054": [["block_0", ["ratio yields the age of the rock. Other methods, such as rubidium-strontium dating (Rb-87 decays into Sr-87\nwith a half-life of 48.8 billion years), operate on the same principle. To estimate the lower limit for the earth\u2019s\nage, scientists determine the age of various rocks and minerals, making the assumption that the earth is older\nthan the oldest rocks and minerals in its crust. As of 2014, the oldest known rocks on earth are the Jack Hills\nzircons from Australia, found by uranium-lead dating to be almost 4.4 billion years old.\n"]], ["block_1", [" Radioactive Dating of Rocks \n"]], ["block_2", ["An igneous rock contains 9.58\n10g of U-238 and 2.51\n10g of Pb-206, and much, much smaller\n"]], ["block_3", ["amounts of Pb-208. Determine the approximate time at which the rock formed.\n"]], ["block_4", [" Solution \n"]], ["block_5", ["The sample of rock contains very little Pb-208, the most common isotope of lead, so we can safely assume that\nall the Pb-206 in the rock was produced by the radioactive decay of U-238. When the rock formed, it contained\nall of the U-238 currently in it, plus some U-238 that has since undergone radioactive decay.\n"]], ["block_6", ["The amount of U-238 currently in the rock is:\n"]], ["block_7", ["Because when one mole of U-238 decays, it produces one mole of Pb-206, the amount of U-238 that has\nundergone radioactive decay since the rock was formed is:\n"]], ["block_8", ["The total amount of U-238 originally present in the rock is therefore:\n"]], ["block_9", ["The amount of time that has passed since the formation of the rock is given by:\n"]], ["block_10", ["with N0 representing the original amount of U-238 and Nt representing the present amount of U-238.\n"]], ["block_11", ["U-238 decays into Pb-206 with a half-life of 4.5\n10y, so the decay constant \u03bb is:\n"]], ["block_12", ["Substituting and solving, we have:\n"]], ["block_13", ["Therefore, the rock is approximately 1.7 billion years old.\n"]], ["block_14", [" Check Your Learning \n"]], ["block_15", ["A sample of rock contains 6.14\n10g of Rb-87 and 3.51\n10g of Sr-87. Calculate the age of the rock. (The\n"]], ["block_16", ["half-life of the \u03b2 decay of Rb-87 is 4.7\n10y.)\n"]], ["block_17", [" Answer: \n3.7\n10y\n"]], ["block_18", ["EXAMPLE 21.7\n"]], ["block_19", [" 21.3 \u2022 Radioactive Decay \n 1041 \n"]]], "page_1055": [["block_0", [" 1042 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", [" 21.4 Transmutation and Nuclear Energy \n"]], ["block_2", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_3", ["After the discovery of radioactivity, the field of nuclear chemistry was created and developed rapidly during\nthe early twentieth century. A slew of new discoveries in the 1930s and 1940s, along with World War II,\ncombined to usher in the Nuclear Age in the mid-twentieth century. Scientists learned how to create new\nsubstances, and certain isotopes of certain elements were found to possess the capacity to produce\nunprecedented amounts of energy, with the potential to cause tremendous damage during war, as well as\nproduce enormous amounts of power for society\u2019s needs during peace.\n"]], ["block_4", [" Synthesis of Nuclides \n"]], ["block_5", [" Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a\nnucleus, or the reaction of a nucleus with another particle. The first manmade nucleus was produced in Ernest\nRutherford\u2019s laboratory in 1919 by a transmutation reaction, the bombardment of one type of nuclei with\nother nuclei or with neutrons. Rutherford bombarded nitrogen atoms with high-speed \u03b1 particles from a\nnatural radioactive isotope of radium and observed protons resulting from the reaction:\n"]], ["block_6", ["The\nand\nnuclei that are produced are stable, so no further (nuclear) changes occur.\n"]], ["block_7", ["To reach the kinetic energies necessary to produce transmutation reactions, devices called particle \n accelerators are used. These devices use magnetic and electric fields to increase the speeds of nuclear\nparticles. In all accelerators, the particles move in a vacuum to avoid collisions with gas molecules. When\nneutrons are required for transmutation reactions, they are usually obtained from radioactive decay reactions\nor from various nuclear reactions occurring in nuclear reactors. The Chemistry in Everyday Life feature that\nfollows discusses a famous particle accelerator that made worldwide news.\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", ["\u2022\nDescribe the synthesis of transuranium nuclides\n"]], ["block_10", ["\u2022\nExplain nuclear fission and fusion processes\n"]], ["block_11", ["\u2022\nRelate the concepts of critical mass and nuclear chain reactions\n"]], ["block_12", ["\u2022\nSummarize basic requirements for nuclear fission and fusion reactors\n"]], ["block_13", ["Chemistry in Everyday Life\n"]], ["block_14", [" CERN Particle Accelerator \nLocated near Geneva, the CERN (\u201cConseil Europ\u00e9en pour la Recherche Nucl\u00e9aire,\u201d or European Council for\nNuclear Research) Laboratory is the world\u2019s premier center for the investigations of the fundamental\nparticles that make up matter. It contains the 27-kilometer (17 mile) long, circular Large Hadron Collider\n(LHC), the largest particle accelerator in the world (Figure 21.13). In the LHC, particles are boosted to high\nenergies and are then made to collide with each other or with stationary targets at nearly the speed of light.\nSuperconducting electromagnets are used to produce a strong magnetic field that guides the particles\naround the ring. Specialized, purpose-built detectors observe and record the results of these collisions,\nwhich are then analyzed by CERN scientists using powerful computers.\n"]]], "page_1056": [["block_0", ["Famous physicist Brian Cox talks about his work on the Large Hadron Collider at CERN, providing an\nentertaining and engaging tour (http://openstax.org/l/16tedCERN) of this massive project and the physics\nbehind it.\n"]], ["block_1", ["View a short video (http://openstax.org/l/16CERNvideo) from CERN, describing the basics of how its particle\naccelerators work.\n"]], ["block_2", ["Prior to 1940, the heaviest-known element was uranium, whose atomic number is 92. Now, many artificial\nelements have been synthesized and isolated, including several on such a large scale that they have had a\nprofound effect on society. One of these\u2014element 93, neptunium (Np)\u2014was first made in 1940 by McMillan\nand Abelson by bombarding uranium-238 with neutrons. The reaction creates unstable uranium-239, with a\nhalf-life of 23.5 minutes, which then decays into neptunium-239. Neptunium-239 is also radioactive, with a\nhalf-life of 2.36 days, and it decays into plutonium-239. The nuclear reactions are:\n"]], ["block_3", ["Plutonium is now mostly formed in nuclear reactors as a byproduct during the fission of U-235. Additional\nneutrons are released during this fission process (see the next section), some of which combine with U-238\nnuclei to form uranium-239; this undergoes \u03b2 decay to form neptunium-239, which in turn undergoes \u03b2 decay\nto form plutonium-239 as illustrated in the preceding three equations. These processes are summarized in the\nequation:\n"]], ["block_4", ["Heavier isotopes of plutonium\u2014Pu-240, Pu-241, and Pu-242\u2014are also produced when lighter plutonium\n"]], ["block_5", ["In 2012, CERN announced that experiments at the LHC showed the first observations of the Higgs boson,\nan elementary particle that helps explain the origin of mass in fundamental particles. This long-\nanticipated discovery made worldwide news and resulted in the awarding of the 2013 Nobel Prize in\nPhysics to Fran\u00e7ois Englert and Peter Higgs, who had predicted the existence of this particle almost 50\nyears previously.\n"]], ["block_6", [" FIGURE 21.13 \nA small section of the LHC is shown with workers traveling along it. (credit: Christophe Delaere)\n"]], ["block_7", ["LINK TO LEARNING\n"]], ["block_8", [{"image_0": "1056_0.png", "coords": [189, 57, 423, 233]}]], ["block_9", [" 21.4 \u2022 Transmutation and Nuclear Energy \n 1043 \n"]]], "page_1057": [["block_0", [" 1044 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", ["nuclei capture neutrons. Some of this highly radioactive plutonium is used to produce military weapons, and\nthe rest presents a serious storage problem because they have half-lives from thousands to hundreds of\nthousands of years.\n"]], ["block_2", ["Although they have not been prepared in the same quantity as plutonium, many other synthetic nuclei have\nbeen produced. Nuclear medicine has developed from the ability to convert atoms of one type into other types\nof atoms. Radioactive isotopes of several dozen elements are currently used for medical applications. The\nradiation produced by their decay is used to image or treat various organs or portions of the body, among other\nuses.\n"]], ["block_3", ["The elements beyond element 92 (uranium) are called transuranium elements . As of this writing, 22\ntransuranium elements have been produced and officially recognized by IUPAC; several other elements have\nformation claims that are waiting for approval. Some of these elements are shown in Table 21.3.\n"]], ["block_4", [" Nuclear Fission \n"]], ["block_5", ["Many heavier elements with smaller binding energies per nucleon can decompose into more stable elements\nthat have intermediate mass numbers and larger binding energies per nucleon\u2014that is, mass numbers and\nbinding energies per nucleon that are closer to the \u201cpeak\u201d of the binding energy graph near 56 (see Figure\n21.3). Sometimes neutrons are also produced. This decomposition is called fission , the breaking of a large\nnucleus into smaller pieces. The breaking is rather random with the formation of a large number of different\nproducts. Fission usually does not occur naturally, but is induced by bombardment with neutrons. The first\nreported nuclear fission occurred in 1939 when three German scientists, Lise Meitner, Otto Hahn, and Fritz\nStrassman, bombarded uranium-235 atoms with slow-moving neutrons that split the U-238 nuclei into\nsmaller fragments that consisted of several neutrons and elements near the middle of the periodic table. Since\nthen, fission has been observed in many other isotopes, including most actinide isotopes that have an odd\nnumber of neutrons. A typical nuclear fission reaction is shown in Figure 21.14.\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [" TABLE 21.3 \n"]], ["block_8", [" Name \n Symbol \n Atomic Number \n Reaction \n"]], ["block_9", ["americium\nAm\n95\n"]], ["block_10", ["curium\nCm\n96\n"]], ["block_11", ["californium\nCf\n98\n"]], ["block_12", ["einsteinium\nEs\n99\n"]], ["block_13", ["mendelevium\nMd\n101\n"]], ["block_14", ["nobelium\nNo\n102\n"]], ["block_15", ["rutherfordium\nRf\n104\n"]], ["block_16", ["seaborgium\nSg\n106\n"]], ["block_17", ["meitnerium\nMt\n107\n"]], ["block_18", ["Preparation of Some of the Transuranium Elements\n"]]], "page_1058": [["block_0", [{"image_0": "1058_0.png", "coords": [72, 57, 540, 264]}]], ["block_1", [" FIGURE 21.14 \nWhen a slow neutron hits a fissionable U-235 nucleus, it is absorbed and forms an unstable U-236\n"]], ["block_2", ["nucleus. The U-236 nucleus then rapidly breaks apart into two smaller nuclei (in this case, Ba-141 and Kr-92) along\nwith several neutrons (usually two or three), and releases a very large amount of energy.\n"]], ["block_3", ["Among the products of Meitner, Hahn, and Strassman\u2019s fission reaction were barium, krypton, lanthanum, and\ncerium, all of which have nuclei that are more stable than uranium-235. Since then, hundreds of different\nisotopes have been observed among the products of fissionable substances. A few of the many reactions that\noccur for U-235, and a graph showing the distribution of its fission products and their yields, are shown in\nFigure 21.15. Similar fission reactions have been observed with other uranium isotopes, as well as with a\nvariety of other isotopes such as those of plutonium.\n"]], ["block_4", [{"image_1": "1058_1.png", "coords": [72, 393, 540, 613]}]], ["block_5", [" FIGURE 21.15 \n(a) Nuclear fission of U-235 produces a range of fission products. (b) The larger fission products of\n"]], ["block_6", ["U-235 are typically one isotope with a mass number around 85\u2013105, and another isotope with a mass number that\nis about 50% larger, that is, about 130\u2013150.\n"]], ["block_7", ["View this link (http://openstax.org/l/16fission) to see a simulation of nuclear fission.\n"]], ["block_8", ["A tremendous amount of energy is produced by the fission of heavy elements. For instance, when one mole of\n"]], ["block_9", ["LINK TO LEARNING\n"]], ["block_10", [" 21.4 \u2022 Transmutation and Nuclear Energy \n 1045 \n"]]], "page_1059": [["block_0", [" 1046 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", ["U-235 undergoes fission, the products weigh about 0.2 grams less than the reactants; this \u201clost\u201d mass is\nconverted into a very large amount of energy, about 1.8\n10kJ per mole of U-235. Nuclear fission reactions\n"]], ["block_2", ["produce incredibly large amounts of energy compared to chemical reactions. The fission of 1 kilogram of\nuranium-235, for example, produces about 2.5 million times as much energy as is produced by burning 1\nkilogram of coal.\n"]], ["block_3", ["As described earlier, when undergoing fission U-235 produces two \u201cmedium-sized\u201d nuclei, and two or three\nneutrons. These neutrons may then cause the fission of other uranium-235 atoms, which in turn provide more\nneutrons that can cause fission of even more nuclei, and so on. If this occurs, we have a nuclear chain reaction \n(see Figure 21.16). On the other hand, if too many neutrons escape the bulk material without interacting with a\nnucleus, then no chain reaction will occur.\n"]], ["block_4", [{"image_0": "1059_0.png", "coords": [72, 196, 540, 691]}]], ["block_5", [" FIGURE 21.16 \nThe fission of a large nucleus, such as U-235, produces two or three neutrons, each of which is\n"]], ["block_6", ["capable of causing fission of another nucleus by the reactions shown. If this process continues, a nuclear chain\nreaction occurs.\n"]], ["block_7", [" Access for free at openstax.org \n"]]], "page_1060": [["block_0", ["Material that can sustain a nuclear fission chain reaction is said to be fissile or fissionable . (Technically, fissile\nmaterial can undergo fission with neutrons of any energy, whereas fissionable material requires high-energy\nneutrons.) Nuclear fission becomes self-sustaining when the number of neutrons produced by fission equals\nor exceeds the number of neutrons absorbed by splitting nuclei plus the number that escape into the\nsurroundings. The amount of a fissionable material that will support a self-sustaining chain reaction is a\n critical mass . An amount of fissionable material that cannot sustain a chain reaction is a subcritical mass . An\namount of material in which there is an increasing rate of fission is known as a supercritical mass . The\ncritical mass depends on the type of material: its purity, the temperature, the shape of the sample, and how the\nneutron reactions are controlled (Figure 21.17).\n"]], ["block_1", [" FIGURE 21.17 \n(a) In a subcritical mass, the fissile material is too small and allows too many neutrons to escape\n"]], ["block_2", ["the material, so a chain reaction does not occur. (b) In a critical mass, a large enough number of neutrons in the\nfissile material induce fission to create a chain reaction.\n"]], ["block_3", ["An atomic bomb (Figure 21.18) contains several pounds of fissionable material,\nor\na source of\n"]], ["block_4", ["neutrons, and an explosive device for compressing it quickly into a small volume. When fissionable material is\nin small pieces, the proportion of neutrons that escape through the relatively large surface area is great, and a\nchain reaction does not take place. When the small pieces of fissionable material are brought together quickly\nto form a body with a mass larger than the critical mass, the relative number of escaping neutrons decreases,\nand a chain reaction and explosion result.\n"]], ["block_5", [{"image_0": "1060_0.png", "coords": [130, 177, 481, 372]}]], ["block_6", [" 21.4 \u2022 Transmutation and Nuclear Energy \n 1047 \n"]]], "page_1061": [["block_0", [" 1048 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", [{"image_0": "1061_0.png", "coords": [72, 57, 540, 403]}]], ["block_2", [" FIGURE 21.18 \n(a) The nuclear fission bomb that destroyed Hiroshima on August 6, 1945, consisted of two\n"]], ["block_3", ["subcritical masses of U-235, where conventional explosives were used to fire one of the subcritical masses into the\nother, creating the critical mass for the nuclear explosion. (b) The plutonium bomb that destroyed Nagasaki on\nAugust 9, 1945, consisted of a hollow sphere of plutonium that was rapidly compressed by conventional explosives.\nThis led to a concentration of plutonium in the center that was greater than the critical mass necessary for the\nnuclear explosion.\n"]], ["block_4", [" Fission Reactors \nChain reactions of fissionable materials can be controlled and sustained without an explosion in a nuclear \n reactor (Figure 21.19). Any nuclear reactor that produces power via the fission of uranium or plutonium by\nbombardment with neutrons must have at least five components: nuclear fuel consisting of fissionable\nmaterial, a nuclear moderator, reactor coolant, control rods, and a shield and containment system. We will\ndiscuss these components in greater detail later in the section. The reactor works by separating the fissionable\nnuclear material such that a critical mass cannot be formed, controlling both the flux and absorption of\nneutrons to allow shutting down the fission reactions. In a nuclear reactor used for the production of\nelectricity, the energy released by fission reactions is trapped as thermal energy and used to boil water and\nproduce steam. The steam is used to turn a turbine, which powers a generator for the production of electricity.\n"]], ["block_5", [" Access for free at openstax.org \n"]]], "page_1062": [["block_0", [{"image_0": "1062_0.png", "coords": [72, 57, 540, 272]}]], ["block_1", [" FIGURE 21.19 \n(a) The Diablo Canyon Nuclear Power Plant near San Luis Obispo is the only nuclear power plant\n"]], ["block_2", ["currently in operation in California. The domes are the containment structures for the nuclear reactors, and the\nbrown building houses the turbine where electricity is generated. Ocean water is used for cooling. (b) The Diablo\nCanyon uses a pressurized water reactor, one of a few different fission reactor designs in use around the world, to\nproduce electricity. Energy from the nuclear fission reactions in the core heats water in a closed, pressurized\nsystem. Heat from this system produces steam that drives a turbine, which in turn produces electricity. (credit a:\nmodification of work by \u201cMike\u201d Michael L. Baird; credit b: modification of work by the Nuclear Regulatory\nCommission)\n"]], ["block_3", [" Nuclear Fuels \n"]], ["block_4", [" Nuclear fuel consists of a fissionable isotope, such as uranium-235, which must be present in sufficient\nquantity to provide a self-sustaining chain reaction. In the United States, uranium ores contain from\n0.05\u20130.3% of the uranium oxide U3O8; the uranium in the ore is about 99.3% nonfissionable U-238 with only\n0.7% fissionable U-235. Nuclear reactors require a fuel with a higher concentration of U-235 than is found in\nnature; it is normally enriched to have about 5% of uranium mass as U-235. At this concentration, it is not\npossible to achieve the supercritical mass necessary for a nuclear explosion. Uranium can be enriched by\ngaseous diffusion (the only method currently used in the US), using a gas centrifuge, or by laser separation.\n"]], ["block_5", ["In the gaseous diffusion enrichment plant where U-235 fuel is prepared, UF6 (uranium hexafluoride) gas at low\npressure moves through barriers that have holes just barely large enough for UF6 to pass through. The slightly\nlighter UF6 molecules diffuse through the barrier slightly faster than the heavier UF6 molecules. This\nprocess is repeated through hundreds of barriers, gradually increasing the concentration of UF6 to the level\nneeded by the nuclear reactor. The basis for this process, Graham\u2019s law, is described in the chapter on gases.\nThe enriched UF6 gas is collected, cooled until it solidifies, and then taken to a fabrication facility where it is\nmade into fuel assemblies. Each fuel assembly consists of fuel rods that contain many thimble-sized, ceramic-\nencased, enriched uranium (usually UO2) fuel pellets. Modern nuclear reactors may contain as many as 10\nmillion fuel pellets. The amount of energy in each of these pellets is equal to that in almost a ton of coal or 150\ngallons of oil.\n"]], ["block_6", [" Nuclear Moderators \n"]], ["block_7", ["Neutrons produced by nuclear reactions move too fast to cause fission (refer back to Figure 21.17). They must\nfirst be slowed to be absorbed by the fuel and produce additional nuclear reactions. A nuclear moderator is a\nsubstance that slows the neutrons to a speed that is low enough to cause fission. Early reactors used high-\npurity graphite as a moderator. Modern reactors in the US exclusively use heavy water\nor light water\n"]], ["block_8", ["(ordinary H2O), whereas some reactors in other countries use other materials, such as carbon dioxide,\nberyllium, or graphite.\n"]], ["block_9", [" 21.4 \u2022 Transmutation and Nuclear Energy \n 1049 \n"]]], "page_1063": [["block_0", [" 1050 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", [" Reactor Coolants \n"]], ["block_2", ["A nuclear reactor coolant is used to carry the heat produced by the fission reaction to an external boiler and\nturbine, where it is transformed into electricity. Two overlapping coolant loops are often used; this counteracts\nthe transfer of radioactivity from the reactor to the primary coolant loop. All nuclear power plants in the US\nuse water as a coolant. Other coolants include molten sodium, lead, a lead-bismuth mixture, or molten salts.\n"]], ["block_3", [" Control Rods \n"]], ["block_4", ["Nuclear reactors use control rods (Figure 21.20) to control the fission rate of the nuclear fuel by adjusting the\nnumber of slow neutrons present to keep the rate of the chain reaction at a safe level. Control rods are made of\nboron, cadmium, hafnium, or other elements that are able to absorb neutrons. Boron-10, for example, absorbs\nneutrons by a reaction that produces lithium-7 and alpha particles:\n"]], ["block_5", ["When control rod assemblies are inserted into the fuel element in the reactor core, they absorb a larger\nfraction of the slow neutrons, thereby slowing the rate of the fission reaction and decreasing the power\nproduced. Conversely, if the control rods are removed, fewer neutrons are absorbed, and the fission rate and\nenergy production increase. In an emergency, the chain reaction can be shut down by fully inserting all of the\ncontrol rods into the nuclear core between the fuel rods.\n"]], ["block_6", [{"image_0": "1063_0.png", "coords": [72, 300, 540, 708]}]], ["block_7", [" FIGURE 21.20 \nThe nuclear reactor core shown in (a) contains the fuel and control rod assembly shown in (b).\n"]], ["block_8", [" Access for free at openstax.org \n"]]], "page_1064": [["block_0", ["(credit: modification of work by E. Generalic, http://glossary.periodni.com/glossary.php?en=control+rod)\n"]], ["block_1", [" Shield and Containment System \n"]], ["block_2", ["During its operation, a nuclear reactor produces neutrons and other radiation. Even when shut down, the\ndecay products are radioactive. In addition, an operating reactor is thermally very hot, and high pressures\nresult from the circulation of water or another coolant through it. Thus, a reactor must withstand high\ntemperatures and pressures, and must protect operating personnel from the radiation. Reactors are equipped\nwith a containment system (or shield) that consists of three parts:\n"]], ["block_3", ["In addition, reactors are often covered with a steel or concrete dome that is designed to contain any radioactive\nmaterials might be released by a reactor accident.\n"]], ["block_4", ["Click here to watch a 3-minute video (http://openstax.org/l/16nucreactors) from the Nuclear Energy Institute\non how nuclear reactors work.\n"]], ["block_5", ["Nuclear power plants are designed in such a way that they cannot form a supercritical mass of fissionable\nmaterial and therefore cannot create a nuclear explosion. But as history has shown, failures of systems and\nsafeguards can cause catastrophic accidents, including chemical explosions and nuclear meltdowns (damage\nto the reactor core from overheating). The following Chemistry in Everyday Life feature explores three\ninfamous meltdown incidents.\n"]], ["block_6", ["1.\nThe reactor vessel, a steel shell that is 3\u201320-centimeters thick and, with the moderator, absorbs much of\nthe radiation produced by the reactor\n"]], ["block_7", ["2.\nA main shield of 1\u20133 meters of high-density concrete\n"]], ["block_8", ["3.\nA personnel shield of lighter materials that protects operators from \u03b3 rays and X-rays\n"]], ["block_9", ["Chemistry in Everyday Life\n"]], ["block_10", [" Nuclear Accidents \nThe importance of cooling and containment are amply illustrated by three major accidents that occurred\nwith the nuclear reactors at nuclear power generating stations in the United States (Three Mile Island), the\nformer Soviet Union (Chernobyl), and Japan (Fukushima).\n"]], ["block_11", ["In March 1979, the cooling system of the Unit 2 reactor at Three Mile Island Nuclear Generating Station in\nPennsylvania failed, and the cooling water spilled from the reactor onto the floor of the containment\nbuilding. After the pumps stopped, the reactors overheated due to the high radioactive decay heat\nproduced in the first few days after the nuclear reactor shut down. The temperature of the core climbed to\nat least 2200 \u00b0C, and the upper portion of the core began to melt. In addition, the zirconium alloy cladding\nof the fuel rods began to react with steam and produced hydrogen:\n"]], ["block_12", ["The hydrogen accumulated in the confinement building, and it was feared that there was danger of an\nexplosion of the mixture of hydrogen and air in the building. Consequently, hydrogen gas and radioactive\ngases (primarily krypton and xenon) were vented from the building. Within a week, cooling water\ncirculation was restored and the core began to cool. The plant was closed for nearly 10 years during the\ncleanup process.\n"]], ["block_13", ["Although zero discharge of radioactive material is desirable, the discharge of radioactive krypton and\nxenon, such as occurred at the Three Mile Island plant, is among the most tolerable. These gases readily\ndisperse in the atmosphere and thus do not produce highly radioactive areas. Moreover, they are noble\ngases and are not incorporated into plant and animal matter in the food chain. Effectively none of the\nheavy elements of the core of the reactor were released into the environment, and no cleanup of the area\noutside of the containment building was necessary (Figure 21.21).\n"]], ["block_14", ["LINK TO LEARNING\n"]], ["block_15", [" 21.4 \u2022 Transmutation and Nuclear Energy \n 1051 \n"]]], "page_1065": [["block_0", [" 1052 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" FIGURE 21.21 \n(a) In this 2010 photo of Three Mile Island, the remaining structures from the damaged Unit 2\n"]], ["block_3", ["reactor are seen on the left, whereas the separate Unit 1 reactor, unaffected by the accident, continues\ngenerating power to this day (right). (b) President Jimmy Carter visited the Unit 2 control room a few days after\nthe accident in 1979.\n"]], ["block_4", ["Another major nuclear accident involving a reactor occurred in April 1986, at the Chernobyl Nuclear Power\nPlant in Ukraine, which was still a part of the former Soviet Union. While operating at low power during an\nunauthorized experiment with some of its safety devices shut off, one of the reactors at the plant became\nunstable. Its chain reaction became uncontrollable and increased to a level far beyond what the reactor was\ndesigned for. The steam pressure in the reactor rose to between 100 and 500 times the full power pressure\nand ruptured the reactor. Because the reactor was not enclosed in a containment building, a large amount\nof radioactive material spewed out, and additional fission products were released, as the graphite (carbon)\nmoderator of the core ignited and burned. The fire was controlled, but over 200 plant workers and\nfirefighters developed acute radiation sickness and at least 32 soon died from the effects of the radiation. It\nis predicted that about 4000 more deaths will occur among emergency workers and former Chernobyl\nresidents from radiation-induced cancer and leukemia. The reactor has since been encapsulated in steel\nand concrete, a now-decaying structure known as the sarcophagus. Almost 30 years later, significant\nradiation problems still persist in the area, and Chernobyl largely remains a wasteland.\n"]], ["block_5", ["In 2011, the Fukushima Daiichi Nuclear Power Plant in Japan was badly damaged by a 9.0-magnitude\nearthquake and resulting tsunami. Three reactors up and running at the time were shut down\nautomatically, and emergency generators came online to power electronics and coolant systems. However,\nthe tsunami quickly flooded the emergency generators and cut power to the pumps that circulated coolant\nwater through the reactors. High-temperature steam in the reactors reacted with zirconium alloy to\nproduce hydrogen gas. The gas escaped into the containment building, and the mixture of hydrogen and\nair exploded. Radioactive material was released from the containment vessels as the result of deliberate\nventing to reduce the hydrogen pressure, deliberate discharge of coolant water into the sea, and accidental\nor uncontrolled events.\n"]], ["block_6", ["An evacuation zone around the damaged plant extended over 12.4 miles away, and an estimated 200,000\npeople were evacuated from the area. All 48 of Japan\u2019s nuclear power plants were subsequently shut down,\nremaining shuttered as of December 2014. Since the disaster, public opinion has shifted from largely\nfavoring to largely opposing increasing the use of nuclear power plants, and a restart of Japan\u2019s atomic\nenergy program is still stalled (Figure 21.22).\n"]], ["block_7", [{"image_0": "1065_0.png", "coords": [130, 57, 481, 213]}]]], "page_1066": [["block_0", ["The energy produced by a reactor fueled with enriched uranium results from the fission of uranium as well as\nfrom the fission of plutonium produced as the reactor operates. As discussed previously, the plutonium forms\nfrom the combination of neutrons and the uranium in the fuel. In any nuclear reactor, only about 0.1% of the\nmass of the fuel is converted into energy. The other 99.9% remains in the fuel rods as fission products and\nunused fuel. All of the fission products absorb neutrons, and after a period of several months to a few years,\ndepending on the reactor, the fission products must be removed by changing the fuel rods. Otherwise, the\nconcentration of these fission products would increase and absorb more neutrons until the reactor could no\nlonger operate.\n"]], ["block_1", ["Spent fuel rods contain a variety of products, consisting of unstable nuclei ranging in atomic number from 25\nto 60, some transuranium elements, including plutonium and americium, and unreacted uranium isotopes.\nThe unstable nuclei and the transuranium isotopes give the spent fuel a dangerously high level of radioactivity.\nThe long-lived isotopes require thousands of years to decay to a safe level. The ultimate fate of the nuclear\nreactor as a significant source of energy in the United States probably rests on whether or not a politically and\nscientifically satisfactory technique for processing and storing the components of spent fuel rods can be\ndeveloped.\n"]], ["block_2", ["Explore the information in this link (http://openstax.org/l/16wastemgmt) to learn about the approaches to\nnuclear waste management.\n"]], ["block_3", [" Nuclear Fusion and Fusion Reactors \n"]], ["block_4", ["The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass\ninto large amounts of energy, a process called fusion . The principal source of energy in the sun is a net fusion\nreaction in which four hydrogen nuclei fuse and produce one helium nucleus and two positrons. This is a net\nreaction of a more complicated series of events:\n"]], ["block_5", ["A helium nucleus has a mass that is 0.7% less than that of four hydrogen nuclei; this lost mass is converted\ninto energy during the fusion. This reaction produces about 3.6\n10kJ of energy per mole of\nproduced.\n"]], ["block_6", ["This is somewhat larger than the energy produced by the nuclear fission of one mole of U-235 (1.8\n10kJ),\n"]], ["block_7", ["and over 3 million times larger than the energy produced by the (chemical) combustion of one mole of octane\n(5471 kJ).\n"]], ["block_8", [" FIGURE 21.22 \n(a) After the accident, contaminated waste had to be removed, and (b) an evacuation zone was\n"]], ["block_9", ["set up around the plant in areas that received heavy doses of radioactive fallout. (credit a: modification of work\nby \u201cLive Action Hero\u201d/Flickr)\n"]], ["block_10", [{"image_0": "1066_0.png", "coords": [90, 57, 522, 217]}]], ["block_11", ["LINK TO LEARNING\n"]], ["block_12", [" 21.4 \u2022 Transmutation and Nuclear Energy \n 1053 \n"]]], "page_1067": [["block_0", [" 1054 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", ["It has been determined that the nuclei of the heavy isotopes of hydrogen, a deuteron,\nand a triton,\n"]], ["block_2", ["undergo fusion at extremely high temperatures (thermonuclear fusion). They form a helium nucleus and a\nneutron:\n"]], ["block_3", ["This change proceeds with a mass loss of 0.0188 amu, corresponding to the release of 1.69\n10kilojoules per\n"]], ["block_4", ["mole of\nformed. The very high temperature is necessary to give the nuclei enough kinetic energy to\n"]], ["block_5", ["overcome the very strong repulsive forces resulting from the positive charges on their nuclei so they can\ncollide.\n"]], ["block_6", ["Useful fusion reactions require very high temperatures for their initiation\u2014about 15,000,000 K or more. At\nthese temperatures, all molecules dissociate into atoms, and the atoms ionize, forming plasma. These\nconditions occur in an extremely large number of locations throughout the universe\u2014stars are powered by\nfusion. Humans have already figured out how to create temperatures high enough to achieve fusion on a large\nscale in thermonuclear weapons. A thermonuclear weapon such as a hydrogen bomb contains a nuclear\nfission bomb that, when exploded, gives off enough energy to produce the extremely high temperatures\nnecessary for fusion to occur.\n"]], ["block_7", ["Another much more beneficial way to create fusion reactions is in a fusion reactor , a nuclear reactor in which\nfusion reactions of light nuclei are controlled. Because no solid materials are stable at such high temperatures,\nmechanical devices cannot contain the plasma in which fusion reactions occur. Two techniques to contain\nplasma at the density and temperature necessary for a fusion reaction are currently the focus of intensive\nresearch efforts: containment by a magnetic field and by the use of focused laser beams (Figure 21.23). A\nnumber of large projects are working to attain one of the biggest goals in science: getting hydrogen fuel to\nignite and produce more energy than the amount supplied to achieve the extremely high temperatures and\npressures that are required for fusion. At the time of this writing, there are no self-sustaining fusion reactors\noperating in the world, although small-scale controlled fusion reactions have been run for very brief periods.\n"]], ["block_8", [" FIGURE 21.23 \n(a) This model is of the International Thermonuclear Experimental Reactor (ITER) reactor. Currently\n"]], ["block_9", ["under construction in the south of France with an expected completion date of 2027, the ITER will be the world\u2019s\nlargest experimental Tokamak nuclear fusion reactor with a goal of achieving large-scale sustained energy\nproduction. (b) In 2012, the National Ignition Facility at Lawrence Livermore National Laboratory briefly produced\nover 500,000,000,000 watts (500 terawatts, or 500 TW) of peak power and delivered 1,850,000 joules (1.85 MJ) of\nenergy, the largest laser energy ever produced and 1000 times the power usage of the entire United States in any\ngiven moment. Although lasting only a few billionths of a second, the 192 lasers attained the conditions needed for\nnuclear fusion ignition. This image shows the target prior to the laser shot. (credit a: modification of work by Stephan\nMosel)\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [{"image_0": "1067_0.png", "coords": [130, 396, 481, 562]}]]], "page_1068": [["block_0", [" 21.5 Uses of Radioisotopes \n"]], ["block_1", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_2", ["Radioactive isotopes have the same chemical properties as stable isotopes of the same element, but they emit\nradiation, which can be detected. If we replace one (or more) atom(s) with radioisotope(s) in a compound, we\ncan track them by monitoring their radioactive emissions. This type of compound is called a radioactive \n tracer (or radioactive label ). Radioisotopes are used to follow the paths of biochemical reactions or to\ndetermine how a substance is distributed within an organism. Radioactive tracers are also used in many\nmedical applications, including both diagnosis and treatment. They are used to measure engine wear, analyze\nthe geological formation around oil wells, and much more.\n"]], ["block_3", ["Radioimmunossays (RIA), for example, rely on radioisotopes to detect the presence and/or concentration of\ncertain antigens. Developed by Rosalyn Sussman Yalow and Solomon Berson in the 1950s, the technique is\nknown for extreme sensitivity, meaning that it can detect and measure very small quantities of a substance.\nPrior to its discovery, most similar detection relied on large enough quantities to produce visible outcomes.\nRIA revolutionized and expanded entire fields of study, most notably endocrinology, and is commonly used in\nnarcotics detection, blood bank screening, early cancer screening, hormone measurement, and allergy\ndiagnosis. Based on her significant contribution to medicine, Yalow received a Nobel Prize, making her the\nsecond woman to be awarded the prize for medicine.\n"]], ["block_4", ["Radioisotopes have revolutionized medical practice (see Appendix M), where they are used extensively. Over\n10 million nuclear medicine procedures and more than 100 million nuclear medicine tests are performed\nannually in the United States. Four typical examples of radioactive tracers used in medicine are technetium-99\n"]], ["block_5", ["and lungs absorb certain compounds of technetium-99 preferentially. After it is injected, the location of the\ntechnetium compound, and hence the damaged tissue, can be determined by detecting the \u03b3 rays emitted by\nthe Tc-99 isotope. Thallium-201 (Figure 21.24) becomes concentrated in healthy heart tissue, so the two\nisotopes, Tc-99 and Tl-201, are used together to study heart tissue. Iodine-131 concentrates in the thyroid\ngland, the liver, and some parts of the brain. It can therefore be used to monitor goiter and treat thyroid\nconditions, such as Grave\u2019s disease, as well as liver and brain tumors. Salt solutions containing compounds of\nsodium-24 are injected into the bloodstream to help locate obstructions to the flow of blood.\n"]], ["block_6", ["\u2022\nList common applications of radioactive isotopes\n"]], ["block_7", [", thallium-201\n, iodine-131\n, and sodium-24\n. Damaged tissues in the heart, liver,\n"]], ["block_8", [" 21.5 \u2022 Uses of Radioisotopes \n 1055 \n"]]], "page_1069": [["block_0", [" 1056 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", [" FIGURE 21.24 \nAdministering thallium-201 to a patient and subsequently performing a stress test offer medical\n"]], ["block_2", ["professionals an opportunity to visually analyze heart function and blood flow. (credit: modification of work by\n\u201cBlue0ctane\u201d/Wikimedia Commons)\n"]], ["block_3", ["Radioisotopes used in medicine typically have short half-lives\u2014for example, the ubiquitous Tc-99m has a half-\nlife of 6.01 hours. This makes Tc-99m essentially impossible to store and prohibitively expensive to transport,\nso it is made on-site instead. Hospitals and other medical facilities use Mo-99 (which is primarily extracted\nfrom U-235 fission products) to generate Tc-99. Mo-99 undergoes \u03b2 decay with a half-life of 66 hours, and the\nTc-99 is then chemically extracted (Figure 21.25). The parent nuclide Mo-99 is part of a molybdate ion,\n"]], ["block_4", ["by column chromatography, with the higher charge molybdate ion adsorbing onto the alumina in the column,\nand the lower charge pertechnetate ion passing through the column in the solution. A few micrograms of\nMo-99 can produce enough Tc-99 to perform as many as 10,000 tests.\n"]], ["block_5", [" FIGURE 21.25 \n(a) The first Tc-99m generator (circa 1958) is used to separate Tc-99 from Mo-99. The\nis\n"]], ["block_6", ["retained by the matrix in the column, whereas the\npasses through and is collected. (b) Tc-99 was used in\n"]], ["block_7", ["this scan of the neck of a patient with Grave\u2019s disease. The scan shows the location of high concentrations of Tc-99.\n(credit a: modification of work by the Department of Energy; credit b: modification of work by \u201cMBq\u201d/Wikimedia\nCommons)\n"]], ["block_8", ["Radioisotopes can also be used, typically in higher doses than as a tracer, as treatment. Radiation therapy is\nthe use of high-energy radiation to damage the DNA of cancer cells, which kills them or keeps them from\ndividing (Figure 21.26). A cancer patient may receive external beam radiation therapy delivered by a\nmachine outside the body, or internal radiation therapy (brachytherapy) from a radioactive substance that\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", ["when it decays, it forms the pertechnetate ion,\nThese two water-soluble ions are separated\n"]], ["block_11", [{"image_0": "1069_0.png", "coords": [189, 57, 423, 303]}]], ["block_12", [{"image_1": "1069_1.png", "coords": [189, 470, 423, 600]}]]], "page_1070": [["block_0", ["has been introduced into the body. Note that chemotherapy is similar to internal radiation therapy in that the\ncancer treatment is injected into the body, but differs in that chemotherapy uses chemical rather than\nradioactive substances to kill the cancer cells.\n"]], ["block_1", [" FIGURE 21.26 \nThe cartoon in (a) shows a cobalt-60 machine used in the treatment of cancer. The diagram in (b)\n"]], ["block_2", ["shows how the gantry of the Co-60 machine swings through an arc, focusing radiation on the targeted region\n(tumor) and minimizing the amount of radiation that passes through nearby regions.\n"]], ["block_3", ["Cobalt-60 is a synthetic radioisotope produced by the neutron activation of Co-59, which then undergoes \u03b2\ndecay to form Ni-60, along with the emission of \u03b3 radiation. The overall process is:\n"]], ["block_4", ["The overall decay scheme for this is shown graphically in Figure 21.27.\n"]], ["block_5", [{"image_0": "1070_0.png", "coords": [72, 486, 540, 711]}]], ["block_6", [" FIGURE 21.27 \nCo-60 undergoes a series of radioactive decays. The \u03b3 emissions are used for radiation therapy.\n"]], ["block_7", [{"image_1": "1070_1.png", "coords": [96, 101, 515, 367]}]], ["block_8", [" 21.5 \u2022 Uses of Radioisotopes \n 1057 \n"]]], "page_1071": [["block_0", [" 1058 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", ["Radioisotopes are used in diverse ways to study the mechanisms of chemical reactions in plants and animals.\nThese include labeling fertilizers in studies of nutrient uptake by plants and crop growth, investigations of\ndigestive and milk-producing processes in cows, and studies on the growth and metabolism of animals and\nplants.\n"]], ["block_2", ["For example, the radioisotope C-14 was used to elucidate the details of how photosynthesis occurs. The overall\nreaction is:\n"]], ["block_3", ["but the process is much more complex, proceeding through a series of steps in which various organic\ncompounds are produced. In studies of the pathway of this reaction, plants were exposed to CO2 containing a\nhigh concentration of\n. At regular intervals, the plants were analyzed to determine which organic\n"]], ["block_4", ["compounds contained carbon-14 and how much of each compound was present. From the time sequence in\nwhich the compounds appeared and the amount of each present at given time intervals, scientists learned\nmore about the pathway of the reaction.\n"]], ["block_5", ["Commercial applications of radioactive materials are equally diverse (Figure 21.28). They include determining\nthe thickness of films and thin metal sheets by exploiting the penetration power of various types of radiation.\nFlaws in metals used for structural purposes can be detected using high-energy gamma rays from cobalt-60 in\na fashion similar to the way X-rays are used to examine the human body. In one form of pest control, flies are\ncontrolled by sterilizing male flies with \u03b3 radiation so that females breeding with them do not produce\noffspring. Many foods are preserved by radiation that kills microorganisms that cause the foods to spoil.\n"]], ["block_6", [{"image_0": "1071_0.png", "coords": [72, 328, 540, 529]}]], ["block_7", [" FIGURE 21.28 \nCommon commercial uses of radiation include (a) X-ray examination of luggage at an airport and (b)\n"]], ["block_8", ["preservation of food. (credit a: modification of work by the Department of the Navy; credit b: modification of work by\nthe US Department of Agriculture)\n"]], ["block_9", ["Americium-241, an \u03b1 emitter with a half-life of 458 years, is used in tiny amounts in ionization-type smoke\ndetectors (Figure 21.29). The \u03b1 emissions from Am-241 ionize the air between two electrode plates in the\nionizing chamber. A battery supplies a potential that causes movement of the ions, thus creating a small\nelectric current. When smoke enters the chamber, the movement of the ions is impeded, reducing the\nconductivity of the air. This causes a marked drop in the current, triggering an alarm.\n"]], ["block_10", [" Access for free at openstax.org \n"]]], "page_1072": [["block_0", [{"image_0": "1072_0.png", "coords": [72, 57, 540, 278]}]], ["block_1", [" FIGURE 21.29 \nInside a smoke detector, Am-241 emits \u03b1 particles that ionize the air, creating a small electric\n"]], ["block_2", ["current. During a fire, smoke particles impede the flow of ions, reducing the current and triggering an alarm. (credit\na: modification of work by \u201cMuffet\u201d/Wikimedia Commons)\n"]], ["block_3", [" 21.6 Biological Effects of Radiation \n"]], ["block_4", [" LEARNING OBJECTIVES \nBy the end of this section, you will be able to:\n"]], ["block_5", ["The increased use of radioisotopes has led to increased concerns over the effects of these materials on\nbiological systems (such as humans). All radioactive nuclides emit high-energy particles or electromagnetic\nwaves. When this radiation encounters living cells, it can cause heating, break chemical bonds, or ionize\nmolecules. The most serious biological damage results when these radioactive emissions fragment or ionize\nmolecules. For example, alpha and beta particles emitted from nuclear decay reactions possess much higher\nenergies than ordinary chemical bond energies. When these particles strike and penetrate matter, they\nproduce ions and molecular fragments that are extremely reactive. The damage this does to biomolecules in\nliving organisms can cause serious malfunctions in normal cell processes, taxing the organism\u2019s repair\nmechanisms and possibly causing illness or even death (Figure 21.30).\n"]], ["block_6", [" FIGURE 21.30 \nRadiation can harm biological systems by damaging the DNA of cells. If this damage is not properly\n"]], ["block_7", ["repaired, the cells may divide in an uncontrolled manner and cause cancer.\n"]], ["block_8", ["\u2022\nDescribe the biological impact of ionizing radiation\n"]], ["block_9", ["\u2022\nDefine units for measuring radiation exposure\n"]], ["block_10", ["\u2022\nExplain the operation of common tools for detecting radioactivity\n"]], ["block_11", ["\u2022\nList common sources of radiation exposure in the US\n"]], ["block_12", [{"image_1": "1072_1.png", "coords": [130, 552, 481, 693]}]], ["block_13", [" 21.6 \u2022 Biological Effects of Radiation \n 1059 \n"]]], "page_1073": [["block_0", [" 1060 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", [" Ionizing and Nonionizing Radiation \n"]], ["block_2", ["There is a large difference in the magnitude of the biological effects of nonionizing radiation (for example,\nlight and microwaves) and ionizing radiation , emissions energetic enough to knock electrons out of molecules\n(for example, \u03b1 and \u03b2 particles, \u03b3 rays, X-rays, and high-energy ultraviolet radiation) (Figure 21.31).\n"]], ["block_3", [{"image_0": "1073_0.png", "coords": [72, 121, 540, 323]}]], ["block_4", [" FIGURE 21.31 \nLower frequency, lower-energy electromagnetic radiation is nonionizing, and higher frequency,\n"]], ["block_5", ["higher-energy electromagnetic radiation is ionizing.\n"]], ["block_6", ["Energy absorbed from nonionizing radiation speeds up the movement of atoms and molecules, which is\nequivalent to heating the sample. Although biological systems are sensitive to heat (as we might know from\ntouching a hot stove or spending a day at the beach in the sun), a large amount of nonionizing radiation is\nnecessary before dangerous levels are reached. Ionizing radiation, however, may cause much more severe\ndamage by breaking bonds or removing electrons in biological molecules, disrupting their structure and\nfunction. The damage can also be done indirectly, by first ionizing H2O (the most abundant molecule in living\norganisms), which forms a H2Oion that reacts with water, forming a hydronium ion and a hydroxyl radical:\n"]], ["block_7", [{"image_1": "1073_1.png", "coords": [72, 452, 334, 484]}]], ["block_8", ["Because the hydroxyl radical has an unpaired electron, it is highly reactive. (This is true of any substance with\nunpaired electrons, known as a free radical.) This hydroxyl radical can react with all kinds of biological\nmolecules (DNA, proteins, enzymes, and so on), causing damage to the molecules and disrupting physiological\nprocesses. Examples of direct and indirect damage are shown in Figure 21.32.\n"]], ["block_9", [{"image_2": "1073_2.png", "coords": [72, 544, 540, 706]}]], ["block_10", [" FIGURE 21.32 \nIonizing radiation can (a) directly damage a biomolecule by ionizing it or breaking its bonds, or (b)\n"]], ["block_11", ["create an H2Oion, which reacts with H2O to form a hydroxyl radical, which in turn reacts with the biomolecule,\n"]], ["block_12", [" Access for free at openstax.org \n"]]], "page_1074": [["block_0", ["causing damage indirectly.\n"]], ["block_1", [" Biological Effects of Exposure to Radiation \nRadiation can harm either the whole body (somatic damage) or eggs and sperm (genetic damage). Its effects\nare more pronounced in cells that reproduce rapidly, such as the stomach lining, hair follicles, bone marrow,\nand embryos. This is why patients undergoing radiation therapy often feel nauseous or sick to their stomach,\nlose hair, have bone aches, and so on, and why particular care must be taken when undergoing radiation\ntherapy during pregnancy.\n"]], ["block_2", ["Different types of radiation have differing abilities to pass through material (Figure 21.33). A very thin barrier,\nsuch as a sheet or two of paper, or the top layer of skin cells, usually stops alpha particles. Because of this,\nalpha particle sources are usually not dangerous if outside the body, but are quite hazardous if ingested or\ninhaled (see the Chemistry in Everyday Life feature on Radon Exposure). Beta particles will pass through a\nhand, or a thin layer of material like paper or wood, but are stopped by a thin layer of metal. Gamma radiation\nis very penetrating and can pass through a thick layer of most materials. Some high-energy gamma radiation\nis able to pass through a few feet of concrete. Certain dense, high atomic number elements (such as lead) can\neffectively attenuate gamma radiation with thinner material and are used for shielding. The ability of various\nkinds of emissions to cause ionization varies greatly, and some particles have almost no tendency to produce\nionization. Alpha particles have about twice the ionizing power of fast-moving neutrons, about 10 times that of\n\u03b2 particles, and about 20 times that of \u03b3 rays and X-rays.\n"]], ["block_3", [{"image_0": "1074_0.png", "coords": [72, 304, 540, 504]}]], ["block_4", [" FIGURE 21.33 \nThe ability of different types of radiation to pass through material is shown. From least to most\n"]], ["block_5", ["penetrating, they are alpha < beta < neutron < gamma.\n"]], ["block_6", ["Chemistry in Everyday Life\n"]], ["block_7", [" Radon Exposure \nFor many people, one of the largest sources of exposure to radiation is from radon gas (Rn-222). Radon-222\nis an \u03b1 emitter with a half\u2013life of 3.82 days. It is one of the products of the radioactive decay series of U-238\n(Figure 21.9), which is found in trace amounts in soil and rocks. The radon gas that is produced slowly\nescapes from the ground and gradually seeps into homes and other structures above. Since it is about eight\ntimes more dense than air, radon gas accumulates in basements and lower floors, and slowly diffuses\nthroughout buildings (Figure 21.34).\n"]], ["block_8", [" 21.6 \u2022 Biological Effects of Radiation \n 1061 \n"]]], "page_1075": [["block_0", [" 1062 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", [" Measuring Radiation Exposure \n"]], ["block_2", ["Several different devices are used to detect and measure radiation, including Geiger counters, scintillation\ncounters (scintillators), and radiation dosimeters (Figure 21.35). Probably the best-known radiation\ninstrument, the Geiger counter (also called the Geiger-M\u00fcller counter) detects and measures radiation.\nRadiation causes the ionization of the gas in a Geiger-M\u00fcller tube. The rate of ionization is proportional to the\namount of radiation. A scintillation counter contains a scintillator\u2014a material that emits light (luminesces)\nwhen excited by ionizing radiation\u2014and a sensor that converts the light into an electric signal. Radiation \n dosimeters also measure ionizing radiation and are often used to determine personal radiation exposure.\nCommonly used types are electronic, film badge, thermoluminescent, and quartz fiber dosimeters.\n"]], ["block_3", [" Access for free at openstax.org \n"]], ["block_4", [" FIGURE 21.34 \nRadon-222 seeps into houses and other buildings from rocks that contain uranium-238, a\n"]], ["block_5", ["radon emitter. The radon enters through cracks in concrete foundations and basement floors, stone or porous\ncinderblock foundations, and openings for water and gas pipes.\n"]], ["block_6", ["Radon is found in buildings across the country, with amounts depending on where you live. The average\nconcentration of radon inside houses in the US (1.25 pCi/L) is about three times the levels found in outside\nair, and about one in six houses have radon levels high enough that remediation efforts to reduce the radon\nconcentration are recommended. Exposure to radon increases one\u2019s risk of getting cancer (especially lung\ncancer), and high radon levels can be as bad for health as smoking a carton of cigarettes a day. Radon is the\nnumber one cause of lung cancer in nonsmokers and the second leading cause of lung cancer overall.\nRadon exposure is believed to cause over 20,000 deaths in the US per year.\n"]], ["block_7", [{"image_0": "1075_0.png", "coords": [90, 57, 522, 421]}]]], "page_1076": [["block_0", [" FIGURE 21.35 \nDevices such as (a) Geiger counters, (b) scintillators, and (c) dosimeters can be used to measure\n"]], ["block_1", ["radiation. (credit c: modification of work by \u201cosaMu\u201d/Wikimedia commons)\n"]], ["block_2", ["A variety of units are used to measure various aspects of radiation (Figure 21.36). The SI unit for rate of\nradioactive decay is the becquerel (Bq) , with 1 Bq = 1 disintegration per second. The curie (Ci) and millicurie \n (mCi) are much larger units and are frequently used in medicine (1 curie = 1 Ci = 3.7\n10disintegrations\n"]], ["block_3", ["per second). The SI unit for measuring radiation dose is the gray (Gy) , with 1 Gy = 1 J of energy absorbed per\nkilogram of tissue. In medical applications, the radiation absorbed dose (rad) is more often used (1 rad = 0.01\nGy; 1 rad results in the absorption of 0.01 J/kg of tissue). The SI unit measuring tissue damage caused by\nradiation is the sievert (Sv) . This takes into account both the energy and the biological effects of the type of\nradiation involved in the radiation dose. The roentgen equivalent for man (rem) is the unit for radiation\ndamage that is used most frequently in medicine (100 rem = 1 Sv). Note that the tissue damage units (rem or\nSv) includes the energy of the radiation dose (rad or Gy) along with a biological factor referred to as the RBE \n(for relative biological effectiveness ) that is an approximate measure of the relative damage done by the\nradiation. These are related by:\n"]], ["block_4", ["with RBE approximately 10 for \u03b1 radiation, 2(+) for protons and neutrons, and 1 for \u03b2 and \u03b3 radiation.\n"]], ["block_5", [{"image_0": "1076_0.png", "coords": [72, 392, 540, 604]}]], ["block_6", [" FIGURE 21.36 \nDifferent units are used to measure the rate of emission from a radioactive source, the energy that\n"]], ["block_7", ["is absorbed from the source, and the amount of damage the absorbed radiation does.\n"]], ["block_8", [" Units of Radiation Measurement \nTable 21.4 summarizes the units used for measuring radiation.\n"]], ["block_9", [{"image_1": "1076_1.png", "coords": [130, 57, 481, 166]}]], ["block_10", [" 21.6 \u2022 Biological Effects of Radiation \n 1063 \n"]]], "page_1077": [["block_0", [" 1064 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", [" TABLE 21.4 \n"]], ["block_2", [" Amount of Radiation \n"]], ["block_3", ["Cobalt-60 (t1/2 = 5.26 y) is used in cancer therapy since the \u03b3 rays it emits can be focused in small areas where\nthe cancer is located. A 5.00-g sample of Co-60 is available for cancer treatment.\n"]], ["block_4", ["(a) What is its activity in Bq?\n"]], ["block_5", ["(b) What is its activity in Ci?\n"]], ["block_6", [" Solution \n"]], ["block_7", ["The activity is given by:\n"]], ["block_8", ["And to convert this to decays per second:\n"]], ["block_9", ["(a) Since 1 Bq =\nthe activity in Becquerel (Bq) is:\n"]], ["block_10", [" Access for free at openstax.org \n"]], ["block_11", [" Measurement \n Purpose \n Unit \n Quantity Measured \n Description \n"]], ["block_12", ["activity of\nsource\n"]], ["block_13", ["absorbed dose\n"]], ["block_14", ["biologically\neffective dose\n"]], ["block_15", ["EXAMPLE 21.8\n"]], ["block_16", ["becquerel (Bq)\n"]], ["block_17", ["curie (Ci)\namount of sample that undergoes 3.7\n"]], ["block_18", ["gray (Gy)\n"]], ["block_19", ["radiation absorbed\ndose (rad)\n1 rad = 0.01 J/kg tissue\n"]], ["block_20", ["sievert (Sv)\n"]], ["block_21", ["roentgen equivalent\nfor man (rem)\nRem = RBE\nrad\n"]], ["block_22", ["Units Used for Measuring Radiation\n"]], ["block_23", ["radioactive decays\nor emissions\n"]], ["block_24", ["energy absorbed per\nkg of tissue\n"]], ["block_25", ["tissue damage\n"]], ["block_26", ["amount of sample that undergoes 1\ndecay/second\n"]], ["block_27", ["1 Gy = 1 J/kg tissue\n"]], ["block_28", ["Sv = RBE\nGy\n"]], ["block_29", ["10decays/second\n"]]], "page_1078": [["block_0", ["(b) Since 1 Ci =\nthe activity in curie (Ci) is:\n"]], ["block_1", [" Check Your Learning \n"]], ["block_2", ["Tritium is a radioactive isotope of hydrogen (t1/2 = 12.32 y) that has several uses, including self-powered\nlighting, in which electrons emitted in tritium radioactive decay cause phosphorus to glow. Its nucleus\ncontains one proton and two neutrons, and the atomic mass of tritium is 3.016 amu. What is the activity of a\nsample containing 1.00mg of tritium (a) in Bq and (b) in Ci?\n"]], ["block_3", [" Answer: \n(a) 3.56\n10Bq; (b) 0.962 Ci\n"]], ["block_4", [" Effects of Long-term Radiation Exposure on the Human Body \n"]], ["block_5", ["The effects of radiation depend on the type, energy, and location of the radiation source, and the length of\nexposure. As shown in Figure 21.37, the average person is exposed to background radiation, including cosmic\nrays from the sun and radon from uranium in the ground (see the Chemistry in Everyday Life feature on Radon\nExposure); radiation from medical exposure, including CAT scans, radioisotope tests, X-rays, and so on; and\nsmall amounts of radiation from other human activities, such as airplane flights (which are bombarded by\nincreased numbers of cosmic rays in the upper atmosphere), radioactivity from consumer products, and a\nvariety of radionuclides that enter our bodies when we breathe (for example, carbon-14) or through the food\nchain (for example, potassium-40, strontium-90, and iodine-131).\n"]], ["block_6", [" FIGURE 21.37 \nThe total annual radiation exposure for a person in the US is about 620 mrem. The various sources\n"]], ["block_7", ["and their relative amounts are shown in this bar graph. (source: U.S. Nuclear Regulatory Commission)\n"]], ["block_8", ["A short-term, sudden dose of a large amount of radiation can cause a wide range of health effects, from\n"]], ["block_9", [{"image_0": "1078_0.png", "coords": [130, 376, 481, 683]}]], ["block_10", [" 21.6 \u2022 Biological Effects of Radiation \n 1065 \n"]]], "page_1079": [["block_0", [" 1066 \n 21 \u2022 Nuclear Chemistry \n"]], ["block_1", ["changes in blood chemistry to death. Short-term exposure to tens of rems of radiation will likely cause very\nnoticeable symptoms or illness; a dose of about 500 rems is estimated to have a 50% probability of causing the\ndeath of the victim within 30 days of exposure. Exposure to radioactive emissions has a cumulative effect on\nthe body during a person\u2019s lifetime, which is another reason why it is important to avoid any unnecessary\nexposure to radiation. Health effects of short-term exposure to radiation are shown in Table 21.5.\n"]], ["block_2", ["It is impossible to avoid some exposure to ionizing radiation. We are constantly exposed to background\nradiation from a variety of natural sources, including cosmic radiation, rocks, medical procedures, consumer\nproducts, and even our own atoms. We can minimize our exposure by blocking or shielding the radiation,\nmoving farther from the source, and limiting the time of exposure.\n"]], ["block_3", ["2 Source: US Environmental Protection Agency\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", [" TABLE 21.5 \n"]], ["block_6", [" Exposure (rem) \n Health Effect \n Time to Onset (without treatment) \n"]], ["block_7", ["5\u201310\nchanges in blood chemistry\n\u2014\n"]], ["block_8", ["50\nnausea\nhours\n"]], ["block_9", ["55\nfatigue\n\u2014\n"]], ["block_10", ["70\nvomiting\n\u2014\n"]], ["block_11", ["75\nhair loss\n2\u20133 weeks\n"]], ["block_12", ["90\ndiarrhea\n\u2014\n"]], ["block_13", ["100\nhemorrhage\n\u2014\n"]], ["block_14", ["400\npossible death\nwithin 2 months\n"]], ["block_15", ["1000\n"]], ["block_16", ["2000\n"]], ["block_17", ["destruction of intestinal lining\n\u2014\n"]], ["block_18", ["internal bleeding\n\u2014\n"]], ["block_19", ["death\n1\u20132 weeks\n"]], ["block_20", ["damage to central nervous system\n\u2014\n"]], ["block_21", ["loss of consciousness;\nminutes\n"]], ["block_22", ["death\nhours to days\n"]], ["block_23", ["Health Effects of Radiation\n"]]], "page_1080": [["block_0", [" Key Terms \n"]], ["block_1", [" alpha ( \u03b1 ) decay \nloss of an alpha particle during\n"]], ["block_2", [" alpha particle \n ( \u03b1 or\nor\nhigh-energy\n"]], ["block_3", [" antimatter \nparticles with the same mass but\n"]], ["block_4", [" band of stability \n(also, belt of stability, zone of\n"]], ["block_5", [" becquerel (Bq) \nSI unit for rate of radioactive decay;\n"]], ["block_6", [" beta ( \u03b2 ) decay \nbreakdown of a neutron into a\n"]], ["block_7", [" beta particle \nor\nor\nhigh-energy\n"]], ["block_8", [" binding energy per nucleon \ntotal binding energy\n"]], ["block_9", ["chain reaction\nrepeated fission caused when the\n"]], ["block_10", [" chemotherapy \nsimilar to internal radiation\n"]], ["block_11", [" containment system \n(also, shield) a three-part\n"]], ["block_12", [" control rod \nmaterial inserted into the fuel\n"]], ["block_13", [" critical mass \namount of fissionable material that\n"]], ["block_14", [" curie (Ci) \nlarger unit for rate of radioactive decay\n"]], ["block_15", [" daughter nuclide \nnuclide produced by the\n"]], ["block_16", [" electron capture \ncombination of a core electron\n"]], ["block_17", ["radioactive decay\n"]], ["block_18", ["helium nucleus; a helium atom that has lost two\nelectrons and contains two protons and two\nneutrons\n"]], ["block_19", ["opposite properties (such as charge) of ordinary\nparticles\n"]], ["block_20", ["stability, or valley of stability) region of graph of\nnumber of protons versus number of neutrons\ncontaining stable (nonradioactive) nuclides\n"]], ["block_21", ["1 Bq = 1 disintegration/s\n"]], ["block_22", ["proton, which remains in the nucleus, and an\nelectron, which is emitted as a beta particle\n"]], ["block_23", ["electron\n"]], ["block_24", ["for the nucleus divided by the number of\nnucleons in the nucleus\n"]], ["block_25", ["neutrons released in fission bombard other\natoms\n"]], ["block_26", ["therapy, but chemical rather than radioactive\nsubstances are introduced into the body to kill\ncancer cells\n"]], ["block_27", ["structure of materials that protects the exterior of\na nuclear fission reactor and operating personnel\nfrom the high temperatures, pressures, and\nradiation levels inside the reactor\n"]], ["block_28", ["assembly that absorbs neutrons and can be\nraised or lowered to adjust the rate of a fission\nreaction\n"]], ["block_29", ["will support a self-sustaining (nuclear fission)\nchain reaction\n"]], ["block_30", ["frequently used in medicine; 1 Ci = 3.7\n10\n"]], ["block_31", ["disintegrations/s\n"]], ["block_32", ["radioactive decay of another nuclide; may be\nstable or may decay further\n"]], ["block_33", ["with a proton to yield a neutron within the\nnucleus\n"]], ["block_34", [" electron volt (eV) \nmeasurement unit of nuclear\n"]], ["block_35", [" external beam radiation therapy \nradiation\n"]], ["block_36", [" fissile (or fissionable) \nwhen a material is capable\n"]], ["block_37", [" fission \nsplitting of a heavier nucleus into two or\n"]], ["block_38", [" fusion \ncombination of very light nuclei into\n"]], ["block_39", [" fusion reactor \nnuclear reactor in which fusion\n"]], ["block_40", [" gamma ( \u03b3 ) emission \ndecay of an excited-state\n"]], ["block_41", [" gamma ray \n ( \u03b3 or\nshort wavelength, high-\n"]], ["block_42", [" Geiger counter \ninstrument that detects and\n"]], ["block_43", [" gray (Gy) \nSI unit for measuring radiation dose; 1\n"]], ["block_44", [" half-life (t 1/2 ) \ntime required for half of the atoms in\n"]], ["block_45", [" internal radiation therapy \n(also, brachytherapy)\n"]], ["block_46", [" ionizing radiation \nradiation that can cause a\n"]], ["block_47", [" magic number \nnuclei with specific numbers of\n"]], ["block_48", [" mass defect \ndifference between the mass of an\n"]], ["block_49", [" mass-energy equivalence equation \nAlbert\n"]], ["block_50", [" millicurie (mCi) \nlarger unit for rate of radioactive\n"]], ["block_51", [" nonionizing radiation \nradiation that speeds up the\n"]], ["block_52", [" nuclear binding energy \nenergy lost when an\n"]], ["block_53", ["binding energies, with 1 eV equaling the amount\nenergy due to the moving an electron across an\nelectric potential difference of 1 volt\n"]], ["block_54", ["delivered by a machine outside the body\n"]], ["block_55", ["of sustaining a nuclear fission reaction\n"]], ["block_56", ["more lighter nuclei, usually accompanied by the\nconversion of mass into large amounts of energy\n"]], ["block_57", ["heavier nuclei, accompanied by the conversion of\nmass into large amounts of energy\n"]], ["block_58", ["reactions of light nuclei are controlled\n"]], ["block_59", ["nuclide accompanied by emission of a gamma ray\n"]], ["block_60", ["energy electromagnetic radiation that exhibits\nwave-particle duality\n"]], ["block_61", ["measures radiation via the ionization produced in\na Geiger-M\u00fcller tube\n"]], ["block_62", ["Gy = 1 J absorbed/kg tissue\n"]], ["block_63", ["a radioactive sample to decay\n"]], ["block_64", ["radiation from a radioactive substance\nintroduced into the body to kill cancer cells\n"]], ["block_65", ["molecule to lose an electron and form an ion\n"]], ["block_66", ["nucleons that are within the band of stability\n"]], ["block_67", ["atom and the summed mass of its constituent\nsubatomic particles (or the mass \u201clost\u201d when\nnucleons are brought together to form a nucleus)\n"]], ["block_68", ["Einstein\u2019s relationship showing that mass and\nenergy are equivalent\n"]], ["block_69", ["decay frequently used in medicine; 1 Ci = 3.7\n10disintegrations/s\n"]], ["block_70", ["movement of atoms and molecules; it is\nequivalent to heating a sample, but is not\nenergetic enough to cause the ionization of\nmolecules\n"]], ["block_71", [" 21 \u2022 Key Terms \n 1067 \n"]]], "page_1081": [["block_0", [" 1068 \n 21 \u2022 Key Equations \n"]], ["block_1", [" nuclear chemistry \nstudy of the structure of atomic\n"]], ["block_2", [" nuclear fuel \nfissionable isotope present in\n"]], ["block_3", [" nuclear moderator \nsubstance that slows neutrons\n"]], ["block_4", [" nuclear reaction \nchange to a nucleus resulting in\n"]], ["block_5", [" nuclear reactor \nenvironment that produces\n"]], ["block_6", [" nuclear transmutation \nconversion of one nuclide\n"]], ["block_7", [" nucleon \ncollective term for protons and neutrons\n"]], ["block_8", [" nuclide \nnucleus of a particular isotope\n"]], ["block_9", [" parent nuclide \nunstable nuclide that changes\n"]], ["block_10", [" particle accelerator \ndevice that uses electric and\n"]], ["block_11", [" positron \n or \nantiparticle to the electron;\n"]], ["block_12", [" positron emission \n(also, \u03b2decay) conversion of a\n"]], ["block_13", [" radiation absorbed dose (rad) \nSI unit for\n"]], ["block_14", [" radiation dosimeter \ndevice that measures ionizing\n"]], ["block_15", [" radiation therapy \nuse of high-energy radiation to\n"]], ["block_16", [" radioactive decay \nspontaneous decay of an\n"]], ["block_17", [" radioactive decay series \nchains of successive\n"]], ["block_18", [" radioactive tracer \n(also, radioactive label)\n"]], ["block_19", [" Key Equations \n"]], ["block_20", [" Access for free at openstax.org \n"]], ["block_21", ["E = mc\n"]], ["block_22", ["atom\u2019s nucleons are bound together (or the\nenergy needed to break a nucleus into its\nconstituent protons and neutrons)\n"]], ["block_23", ["nuclei and processes that change nuclear\nstructure\n"]], ["block_24", ["sufficient quantities to provide a self-sustaining\nchain reaction in a nuclear reactor\n"]], ["block_25", ["to a speed low enough to cause fission\n"]], ["block_26", ["changes in the atomic number, mass number, or\nenergy state\n"]], ["block_27", ["energy via nuclear fission in which the chain\nreaction is controlled and sustained without\nexplosion\n"]], ["block_28", ["into another nuclide\n"]], ["block_29", ["in a nucleus\n"]], ["block_30", ["spontaneously into another (daughter) nuclide\n"]], ["block_31", ["magnetic fields to increase the kinetic energy of\nnuclei used in transmutation reactions\n"]], ["block_32", ["it has identical properties to an electron, except\nfor having the opposite (positive) charge\n"]], ["block_33", ["proton into a neutron, which remains in the\nnucleus, and a positron, which is emitted\n"]], ["block_34", ["measuring radiation dose, frequently used in\nmedical applications; 1 rad = 0.01 Gy\n"]], ["block_35", ["radiation and is used to determine personal\nradiation exposure\n"]], ["block_36", ["damage the DNA of cancer cells, which kills them\nor keeps them from dividing\n"]], ["block_37", ["unstable nuclide into another nuclide\n"]], ["block_38", ["disintegrations (radioactive decays) that\nultimately lead to a stable end-product\n"]], ["block_39", [" radioactivity \nphenomenon exhibited by an\n"]], ["block_40", [" radiocarbon dating \nhighly accurate means of\n"]], ["block_41", [" radioisotope \nisotope that is unstable and\n"]], ["block_42", [" radiometric dating \nuse of radioisotopes and their\n"]], ["block_43", [" reactor coolant \nassembly used to carry the heat\n"]], ["block_44", [" relative biological effectiveness (RBE) \nmeasure of\n"]], ["block_45", [" roentgen equivalent man (rem) \nunit for radiation\n"]], ["block_46", [" scintillation counter \ninstrument that uses a\n"]], ["block_47", [" sievert (Sv) \nSI unit measuring tissue damage\n"]], ["block_48", [" strong nuclear force \nforce of attraction between\n"]], ["block_49", [" subcritical mass \namount of fissionable material\n"]], ["block_50", [" supercritical mass \namount of material in which\n"]], ["block_51", [" transmutation reaction \nbombardment of one type\n"]], ["block_52", [" transuranium element \nelement with an atomic\n"]], ["block_53", ["radioisotope used to track or follow a substance\nby monitoring its radioactive emissions\n"]], ["block_54", ["unstable nucleon that spontaneously undergoes\nchange into a nucleon that is more stable; an\nunstable nucleon is said to be radioactive\n"]], ["block_55", ["dating objects 30,000\u201350,000 years old that were\nderived from once-living matter; achieved by\ncalculating the ratio of\nin the object vs.\n"]], ["block_56", ["the ratio of\nin the present-day\n"]], ["block_57", ["atmosphere\n"]], ["block_58", ["undergoes conversion into a different, more\nstable isotope\n"]], ["block_59", ["properties to date the formation of objects such\nas archeological artifacts, formerly living\norganisms, or geological formations\n"]], ["block_60", ["produced by fission in a reactor to an external\nboiler and turbine where it is transformed into\nelectricity\n"]], ["block_61", ["the relative damage done by radiation\n"]], ["block_62", ["damage, frequently used in medicine; 100 rem =\n1 Sv\n"]], ["block_63", ["scintillator\u2014a material that emits light when\nexcited by ionizing radiation\u2014to detect and\nmeasure radiation\n"]], ["block_64", ["caused by radiation; takes into account energy\nand biological effects of radiation\n"]], ["block_65", ["nucleons that holds a nucleus together\n"]], ["block_66", ["that cannot sustain a chain reaction; less than a\ncritical mass\n"]], ["block_67", ["there is an increasing rate of fission\n"]], ["block_68", ["of nuclei with other nuclei or neutrons\n"]], ["block_69", ["number greater than 92; these elements do not\noccur in nature\n"]]], "page_1082": [["block_0", [" Summary \n"]], ["block_1", [" 21.1 Nuclear Structure and Stability \n"]], ["block_2", ["An atomic nucleus consists of protons and neutrons,\ncollectively called nucleons. Although protons repel\neach other, the nucleus is held tightly together by a\nshort-range, but very strong, force called the strong\nnuclear force. A nucleus has less mass than the total\nmass of its constituent nucleons. This \u201cmissing\u201d\nmass is the mass defect, which has been converted\ninto the binding energy that holds the nucleus\ntogether according to Einstein\u2019s mass-energy\nequivalence equation, E = mc. Of the many nuclides\nthat exist, only a small number are stable. Nuclides\nwith even numbers of protons or neutrons, or those\nwith magic numbers of nucleons, are especially\nlikely to be stable. These stable nuclides occupy a\nnarrow band of stability on a graph of number of\nprotons versus number of neutrons. The binding\nenergy per nucleon is largest for the elements with\nmass numbers near 56; these are the most stable\nnuclei.\n"]], ["block_3", [" 21.2 Nuclear Equations \n"]], ["block_4", ["Nuclei can undergo reactions that change their\nnumber of protons, number of neutrons, or energy\nstate. Many different particles can be involved in\nnuclear reactions. The most common are protons,\nneutrons, positrons (which are positively charged\nelectrons), alpha (\u03b1) particles (which are high-\nenergy helium nuclei), beta (\u03b2) particles (which are\nhigh-energy electrons), and gamma (\u03b3) rays (which\ncompose high-energy electromagnetic radiation). As\nwith chemical reactions, nuclear reactions are\nalways balanced. When a nuclear reaction occurs,\nthe total mass (number) and the total charge remain\nunchanged.\n"]], ["block_5", [" 21.3 Radioactive Decay \n"]], ["block_6", ["Nuclei that have unstable n:p ratios undergo\nspontaneous radioactive decay. The most common\ntypes of radioactivity are \u03b1 decay, \u03b2 decay, \u03b3\nemission, positron emission, and electron capture.\nNuclear reactions also often involve \u03b3 rays, and\nsome nuclei decay by electron capture. Each of these\nmodes of decay leads to the formation of a new\nnucleus with a more stable n:p ratio. Some\n"]], ["block_7", ["decay rate = \u03bbN\n"]], ["block_8", ["rem = RBE\nrad\n"]], ["block_9", ["Sv = RBE\nGy\n"]], ["block_10", ["substances undergo radioactive decay series,\nproceeding through multiple decays before ending\nin a stable isotope. All nuclear decay processes\nfollow first-order kinetics, and each radioisotope has\nits own characteristic half-life, the time that is\nrequired for half of its atoms to decay. Because of the\nlarge differences in stability among nuclides, there\nis a very wide range of half-lives of radioactive\nsubstances. Many of these substances have found\nuseful applications in medical diagnosis and\ntreatment, determining the age of archaeological\nand geological objects, and more.\n"]], ["block_11", [" 21.4 Transmutation and Nuclear Energy \n"]], ["block_12", ["It is possible to produce new atoms by bombarding\nother atoms with nuclei or high-speed particles. The\nproducts of these transmutation reactions can be\nstable or radioactive. A number of artificial\nelements, including technetium, astatine, and the\ntransuranium elements, have been produced in this\nway.\n"]], ["block_13", ["Nuclear power as well as nuclear weapon\ndetonations can be generated through fission\n(reactions in which a heavy nucleus is split into two\nor more lighter nuclei and several neutrons).\nBecause the neutrons may induce additional fission\nreactions when they combine with other heavy\nnuclei, a chain reaction can result. Useful power is\nobtained if the fission process is carried out in a\nnuclear reactor. The conversion of light nuclei into\nheavier nuclei (fusion) also produces energy. At\npresent, this energy has not been contained\nadequately and is too expensive to be feasible for\ncommercial energy production.\n"]], ["block_14", [" 21.5 Uses of Radioisotopes \n"]], ["block_15", ["Compounds known as radioactive tracers can be\nused to follow reactions, track the distribution of a\nsubstance, diagnose and treat medical conditions,\nand much more. Other radioactive substances are\nhelpful for controlling pests, visualizing structures,\nproviding fire warnings, and for many other\napplications. Hundreds of millions of nuclear\nmedicine tests and procedures, using a wide variety\nof radioisotopes with relatively short half-lives, are\n"]], ["block_16", [" 21 \u2022 Summary \n 1069 \n"]]], "page_1083": [["block_0", [" 1070 \n 21 \u2022 Exercises \n"]], ["block_1", ["performed every year in the US. Most of these\nradioisotopes have relatively short half-lives; some\nare short enough that the radioisotope must be\nmade on-site at medical facilities. Radiation therapy\nuses high-energy radiation to kill cancer cells by\ndamaging their DNA. The radiation used for this\ntreatment may be delivered externally or internally.\n"]], ["block_2", [" 21.6 Biological Effects of Radiation \n"]], ["block_3", ["We are constantly exposed to radiation from a\nvariety of naturally occurring and human-produced\nsources. This radiation can affect living organisms.\nIonizing radiation is the most harmful because it can\nionize molecules or break chemical bonds, which\ndamages the molecule and causes malfunctions in\ncell processes. It can also create reactive hydroxyl\nradicals that damage biological molecules and\ndisrupt physiological processes. Radiation can cause\nsomatic or genetic damage, and is most harmful to\n"]], ["block_4", [" Exercises \n"]], ["block_5", [" 21.1 Nuclear Structure and Stability \n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", [" 1 . Write the following isotopes in hyphenated form (e.g., \u201ccarbon-14\u201d)\n"]], ["block_8", [" 2 . Write the following isotopes in nuclide notation (e.g.,\n"]], ["block_9", [" 3 . For the following isotopes that have missing information, fill in the missing information to complete the\n"]], ["block_10", [" 4 . For each of the isotopes in Exercise 21.1, determine the numbers of protons, neutrons, and electrons in a\n"]], ["block_11", [" 5 . Write the nuclide notation, including charge if applicable, for atoms with the following characteristics:\n"]], ["block_12", [" 6 . Calculate the density of the\nnucleus in g/mL, assuming that it has the typical nuclear diameter of 1\n"]], ["block_13", [" 7 . What are the two principal differences between nuclear reactions and ordinary chemical changes?\n"]], ["block_14", ["(a)\n"]], ["block_15", ["(b)\n"]], ["block_16", ["(c)\n"]], ["block_17", ["(d)\n"]], ["block_18", ["(a) oxygen-14\n(b) copper-70\n(c) tantalum-175\n(d) francium-217\n"]], ["block_19", ["notation\n(a)\n"]], ["block_20", ["(b)\n"]], ["block_21", ["(c)\n"]], ["block_22", ["(d)\n"]], ["block_23", ["neutral atom of the isotope.\n"]], ["block_24", ["(a) 25 protons, 20 neutrons, 24 electrons\n(b) 45 protons, 24 neutrons, 43 electrons\n(c) 53 protons, 89 neutrons, 54 electrons\n(d) 97 protons, 146 neutrons, 97 electrons\n"]], ["block_25", ["10cm and is spherical in shape.\n"]], ["block_26", ["rapidly reproducing cells. Types of radiation differ\nin their ability to penetrate material and damage\ntissue, with alpha particles the least penetrating but\npotentially most damaging and gamma rays the\nmost penetrating.\n"]], ["block_27", ["Various devices, including Geiger counters,\nscintillators, and dosimeters, are used to detect and\nmeasure radiation, and monitor radiation exposure.\nWe use several units to measure radiation:\nbecquerels or curies for rates of radioactive decay;\ngray or rads for energy absorbed; and rems or\nsieverts for biological effects of radiation. Exposure\nto radiation can cause a wide range of health effects,\nfrom minor to severe, and including death. We can\nminimize the effects of radiation by shielding with\ndense materials such as lead, moving away from the\nsource, and limiting time of exposure.\n"]]], "page_1084": [["block_0", [" 10 . Which of the following nuclei lie within the band of stability shown in Figure 21.2?\n"]], ["block_1", [" 21.2 Nuclear Equations \n"]], ["block_2", [" 11 . Write a brief description or definition of each of the following:\n"]], ["block_3", [" 12 . Which of the various particles (\u03b1 particles, \u03b2 particles, and so on) that may be produced in a nuclear\n"]], ["block_4", [" 13 . Complete each of the following equations by adding the missing species:\n"]], ["block_5", [" 14 . Complete each of the following equations:\n"]], ["block_6", [" 15 . Write a balanced equation for each of the following nuclear reactions:\n"]], ["block_7", [" 8 . The mass of the atom\nis 22.9898 amu.\n"]], ["block_8", [" 9 . Which of the following nuclei lie within the band of stability shown in Figure 21.2?\n"]], ["block_9", ["(a) Calculate its binding energy per atom in millions of electron volts.\n(b) Calculate its binding energy per nucleon.\n"]], ["block_10", ["(a) chlorine-37\n(b) calcium-40\n(c) Bi\n(d) Fe\n(e) Pb\n(f) Pb\n(g) Rn\n(h) carbon-14\n"]], ["block_11", ["(a) argon-40\n(b) oxygen-16\n(c) Ba\n(d) Ni\n(e) Tl\n(f) Tl\n(g) Ra\n(h) magnesium-24\n"]], ["block_12", ["(a) nucleon\n(b) \u03b1 particle\n(c) \u03b2 particle\n(d) positron\n(e) \u03b3 ray\n(f) nuclide\n(g) mass number\n(h) atomic number\n"]], ["block_13", ["reaction are actually nuclei?\n"]], ["block_14", ["(a)\n"]], ["block_15", ["(b)\n"]], ["block_16", ["(c)\n"]], ["block_17", ["(d)\n"]], ["block_18", ["(a)\n"]], ["block_19", ["(b)\n"]], ["block_20", ["(c)\n"]], ["block_21", ["(d)\n"]], ["block_22", ["(a) the production of O from N by \u03b1 particle bombardment\n(b) the production of C from N by neutron bombardment\n(c) the production of Th from Th by neutron bombardment\n(d) the production of U from U by\nbombardment\n"]], ["block_23", [" 21 \u2022 Exercises \n 1071 \n"]]], "page_1085": [["block_0", [" 1072 \n 21 \u2022 Exercises \n"]], ["block_1", [" 16 . Technetium-99 is prepared from Mo. Molybdenum-98 combines with a neutron to give\n"]], ["block_2", [" 17 . The mass of the atom\nis 18.99840 amu.\n"]], ["block_3", [" 18 . For the reaction\nif 100.0 g of carbon reacts, what volume of nitrogen gas (N2) is\n"]], ["block_4", [" 21.3 Radioactive Decay \n"]], ["block_5", [" 19 . What are the types of radiation emitted by the nuclei of radioactive elements?\n 20 . What changes occur to the atomic number and mass of a nucleus during each of the following decay\n"]], ["block_6", [" 21 . What is the change in the nucleus that results from the following decay scenarios?\n"]], ["block_7", [" 22 . Many nuclides with atomic numbers greater than 83 decay by processes such as electron emission.\n"]], ["block_8", [" 23 . Why is electron capture accompanied by the emission of an X-ray?\n 24 . Explain, in terms of Figure 21.2, how unstable heavy nuclides (atomic number > 83) may decompose to\n"]], ["block_9", [" 25 . Which of the following nuclei is most likely to decay by positron emission? Explain your choice.\n"]], ["block_10", [" 26 . The following nuclei do not lie in the band of stability. How would they be expected to decay? Explain your\n"]], ["block_11", [" 27 . The following nuclei do not lie in the band of stability. How would they be expected to decay?\n"]], ["block_12", [" Access for free at openstax.org \n"]], ["block_13", ["molybdenum-99, an unstable isotope that emits a \u03b2 particle to yield an excited form of technetium-99,\nrepresented as Tc. This excited nucleus relaxes to the ground state, represented as Tc, by emitting a \u03b3\nray. The ground state of Tc then emits a \u03b2 particle. Write the equations for each of these nuclear\nreactions.\n"]], ["block_14", ["(a) Calculate its binding energy per atom in millions of electron volts.\n(b) Calculate its binding energy per nucleon.\n"]], ["block_15", ["produced at 273K and 1 atm?\n"]], ["block_16", ["scenarios?\n(a) an \u03b1 particle is emitted\n(b) a \u03b2 particle is emitted\n(c) \u03b3 radiation is emitted\n(d) a positron is emitted\n(e) an electron is captured\n"]], ["block_17", ["(a) emission of a \u03b2 particle\n(b) emission of a \u03b2particle\n(c) capture of an electron\n"]], ["block_18", ["Explain the observation that the emissions from these unstable nuclides also normally include \u03b1 particles.\n"]], ["block_19", ["form nuclides of greater stability (a) if they are below the band of stability and (b) if they are above the\nband of stability.\n"]], ["block_20", ["(a) chromium-53\n(b) manganese-51\n(c) iron-59\n"]], ["block_21", ["answer.\n(a)\n"]], ["block_22", ["(b)\n"]], ["block_23", ["(c)\n"]], ["block_24", ["(d)\n"]], ["block_25", ["(e)\n"]], ["block_26", ["(a)\n"]], ["block_27", ["(b)\n"]], ["block_28", ["(c)\n"]], ["block_29", ["(d)\n"]], ["block_30", ["(e)\n"]]], "page_1086": [["block_0", [" 28 . Predict by what mode(s) of spontaneous radioactive decay each of the following unstable isotopes might\n"]], ["block_1", [" 29 . Write a nuclear reaction for each step in the formation of\nfrom\nwhich proceeds by a series of\n"]], ["block_2", [" 30 . Write a nuclear reaction for each step in the formation of\nfrom\nwhich proceeds by a series of\n"]], ["block_3", [" 31 . Define the term half-life and illustrate it with an example.\n 32 . A 1.00\n10-g sample of nobelium,\nhas a half-life of 55 seconds after it is formed. What is the\n"]], ["block_4", [" 33 .\n239Pu is a nuclear waste byproduct with a half-life of 24,000 y. What fraction of the 239Pu present today will\nbe present in 1000 y?\n"]], ["block_5", [" 34 . The isotope Tl undergoes \u03b2 decay with a half-life of 3.1 min.\n"]], ["block_6", [" 35 . If 1.000 g of\nproduces 0.0001 mL of the gas\nat STP (standard temperature and pressure) in\n"]], ["block_7", [" 36 . The isotope\nis one of the extremely hazardous species in the residues from nuclear power\n"]], ["block_8", [" 37 . Technetium-99 is often used for assessing heart, liver, and lung damage because certain technetium\n"]], ["block_9", [" 38 . What is the age of mummified primate skin that contains 8.25% of the original quantity of C?\n 39 . A sample of rock was found to contain 8.23 mg of rubidium-87 and 0.47 mg of strontium-87.\n"]], ["block_10", [" 40 . A laboratory investigation shows that a sample of uranium ore contains 5.37 mg of\nand 2.52 mg of\n"]], ["block_11", [" 41 . Plutonium was detected in trace amounts in natural uranium deposits by Glenn Seaborg and his\n"]], ["block_12", [" 42 . A\natom (mass = 7.0169 amu) decays into a\natom (mass = 7.0160 amu) by electron capture. How\n"]], ["block_13", [" 43 . A\natom (mass = 8.0246 amu) decays into a\natom (mass = 8.0053 amu) by loss of a \u03b2particle (mass\n"]], ["block_14", ["proceed:\n(a)\n"]], ["block_15", ["(b)\n"]], ["block_16", ["(c)\n"]], ["block_17", ["(d)\n"]], ["block_18", ["(e) F\n(f) Ba\n(g) Pu\n"]], ["block_19", ["decay reactions involving the step-wise emission of \u03b1, \u03b2, \u03b2, \u03b1, \u03b1, \u03b1 particles, in that order.\n"]], ["block_20", ["decay reactions involving the step-wise emission of \u03b1, \u03b1, \u03b1, \u03b1, \u03b2, \u03b2, \u03b1 particles, in that order.\n"]], ["block_21", ["percentage of\nremaining at the following times?\n"]], ["block_22", ["(a) 5.0 min after it forms\n(b) 1.0 h after it forms\n"]], ["block_23", ["(a) What isotope is produced by the decay?\n(b) How long will it take for 99.0% of a sample of pure Tl to decay?\n(c) What percentage of a sample of pure Tl remains un-decayed after 1.0 h?\n"]], ["block_24", ["24 h, what is the half-life of Ra in years?\n"]], ["block_25", ["generation. The strontium in a 0.500-g sample diminishes to 0.393 g in 10.0 y. Calculate the half-life.\n"]], ["block_26", ["compounds are absorbed by damaged tissues. It has a half-life of 6.0 h. Calculate the rate constant for the\ndecay of\n"]], ["block_27", ["(a) Calculate the age of the rock if the half-life of the decay of rubidium by \u03b2 emission is 4.7\n10y.\n"]], ["block_28", ["(b) If some\nwas initially present in the rock, would the rock be younger, older, or the same age as the\n"]], ["block_29", ["age calculated in (a)? Explain your answer.\n"]], ["block_30", ["associates in 1941. They proposed that the source of this Pu was the capture of neutrons by U nuclei.\nWhy is this plutonium not likely to have been trapped at the time the solar system formed 4.7\n10years\n"]], ["block_31", ["ago?\n"]], ["block_32", ["much energy (in millions of electron volts, MeV) is produced by this reaction?\n"]], ["block_33", ["= 0.00055 amu) or by electron capture. How much energy (in millions of electron volts) is produced by this\nreaction?\n"]], ["block_34", ["Calculate the age of the ore. The half-life of\nis 4.5\n10yr.\n"]], ["block_35", [" 21 \u2022 Exercises \n 1073 \n"]]], "page_1087": [["block_0", [" 1074 \n 21 \u2022 Exercises \n"]], ["block_1", [" 44 . Isotopes such as Al (half-life: 7.2\n10years) are believed to have been present in our solar system as it\n"]], ["block_2", [" 45 . Write a balanced equation for each of the following nuclear reactions:\n"]], ["block_3", [" 46 . Write a balanced equation for each of the following nuclear reactions:\n"]], ["block_4", [" 21.4 Transmutation and Nuclear Energy \n"]], ["block_5", [" 47 . Write the balanced nuclear equation for the production of the following transuranium elements:\n"]], ["block_6", [" 48 . How does nuclear fission differ from nuclear fusion? Why are both of these processes exothermic?\n 49 . Both fusion and fission are nuclear reactions. Why is a very high temperature required for fusion, but not\n"]], ["block_7", [" 50 . Cite the conditions necessary for a nuclear chain reaction to take place. Explain how it can be controlled to\n"]], ["block_8", [" 51 . Describe the components of a nuclear reactor.\n 52 . In usual practice, both a moderator and control rods are necessary to operate a nuclear chain reaction\n"]], ["block_9", [" 53 . Describe how the potential energy of uranium is converted into electrical energy in a nuclear power plant.\n 54 . The mass of a hydrogen atom\nis 1.007825 amu; that of a tritium atom\nis 3.01605 amu; and that\n"]], ["block_10", [" 21.5 Uses of Radioisotopes \n"]], ["block_11", [" 55 . How can a radioactive nuclide be used to show that the equilibrium:\n"]], ["block_12", [" 56 . Technetium-99m has a half-life of 6.01 hours. If a patient injected with technetium-99m is safe to leave\n"]], ["block_13", [" 57 . Iodine that enters the body is stored in the thyroid gland from which it is released to control growth and\n"]], ["block_14", [" Access for free at openstax.org \n"]], ["block_15", ["formed, but have since decayed and are now called extinct nuclides.\n(a) Al decays by \u03b2emission or electron capture. Write the equations for these two nuclear\ntransformations.\n(b) The earth was formed about 4.7\n10(4.7 billion) years ago. How old was the earth when 99.999999%\n"]], ["block_16", ["of the Al originally present had decayed?\n"]], ["block_17", ["(a) bismuth-212 decays into polonium-212\n(b) beryllium-8 and a positron are produced by the decay of an unstable nucleus\n(c) neptunium-239 forms from the reaction of uranium-238 with a neutron and then spontaneously\nconverts into plutonium-239\n(d) strontium-90 decays into yttrium-90\n"]], ["block_18", ["(a) mercury-180 decays into platinum-176\n(b) zirconium-90 and an electron are produced by the decay of an unstable nucleus\n(c) thorium-232 decays and produces an alpha particle and a radium-228 nucleus, which decays into\nactinium-228 by beta decay\n(d) neon-19 decays into fluorine-19\n"]], ["block_19", ["(a) berkelium-244, made by the reaction of Am-241 and He-4\n(b) fermium-254, made by the reaction of Pu-239 with a large number of neutrons\n(c) lawrencium-257, made by the reaction of Cf-250 and B-11\n(d) dubnium-260, made by the reaction of Cf-249 and N-15\n"]], ["block_20", ["for fission?\n"]], ["block_21", ["produce energy, but not produce an explosion.\n"]], ["block_22", ["safely for the purpose of energy production. Cite the function of each and explain why both are necessary.\n"]], ["block_23", ["of an \u03b1 particle is 4.00150 amu. How much energy in kilojoules per mole of\nproduced is released by\n"]], ["block_24", ["the following fusion reaction:\n"]], ["block_25", ["is a dynamic equilibrium?\n"]], ["block_26", ["the hospital once 75% of the dose has decayed, when is the patient allowed to leave?\n"]], ["block_27", ["metabolism. The thyroid can be imaged if iodine-131 is injected into the body. In larger doses, I-133 is\nalso used as a means of treating cancer of the thyroid. I-131 has a half-life of 8.70 days and decays by \u03b2\n"]], ["block_28", ["emission.\n(a) Write an equation for the decay.\n(b) How long will it take for 95.0% of a dose of I-131 to decay?\n"]]], "page_1088": [["block_0", [" 21.6 Biological Effects of Radiation \n"]], ["block_1", [" 58 . If a hospital were storing radioisotopes, what is the minimum containment needed to protect against:\n"]], ["block_2", [" 59 . Based on what is known about Radon-222\u2019s primary decay method, why is inhalation so dangerous?\n 60 . Given specimens uranium-232 (t1/2 = 68.9 y) and uranium-233 (t1/2 = 159,200 y) of equal mass, which one\n"]], ["block_3", [" 61 . A scientist is studying a 2.234 g sample of thorium-229 (t1/2 = 7340 y) in a laboratory.\n"]], ["block_4", [" 62 . Given specimens neon-24 (t1/2 = 3.38 min) and bismuth-211 (t1/2 = 2.14 min) of equal mass, which one\n"]], ["block_5", ["(a) cobalt-60 (a strong \u03b3 emitter used for irradiation)\n(b) molybdenum-99 (a beta emitter used to produce technetium-99 for imaging)\n"]], ["block_6", ["would have greater activity and why?\n"]], ["block_7", ["(a) What is its activity in Bq?\n(b) What is its activity in Ci?\n"]], ["block_8", ["would have greater activity and why?\n"]], ["block_9", [" 21 \u2022 Exercises \n 1075 \n"]]], "page_1089": [["block_0", [" 1076 \n 21 \u2022 Exercises \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_1090": [["block_0", [" APPENDIX A \n"]], ["block_1", [" The Periodic Table \n"]], ["block_2", [{"image_0": "1090_0.png", "coords": [72, 155, 540, 521]}]], ["block_3", [" FIGURE A1 \n"]], ["block_4", [" A \u2022 The Periodic Table \n 1077 \n"]]], "page_1091": [["block_0", [" 1078 \n A \u2022 The Periodic Table \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_1092": [["block_0", [" APPENDIX B \n"]], ["block_1", [" Essential Mathematics \n"]], ["block_2", [" Exponential Arithmetic \n"]], ["block_3", ["Exponential notation is used to express very large and very small numbers as a product of two numbers. The\nfirst number of the product, the digit term, is usually a number not less than 1 and not equal to or greater than\n10. The second number of the product, the exponential term, is written as 10 with an exponent. Some\nexamples of exponential notation are:\n"]], ["block_4", ["The power (exponent) of 10 is equal to the number of places the decimal is shifted to give the digit number. The\nexponential method is particularly useful notation for very large and very small numbers. For example,\n1,230,000,000 = 1.23\n10, and 0.00000000036 = 3.6\n10.\n"]], ["block_5", [" Addition of Exponentials \n"]], ["block_6", ["Convert all numbers to the same power of 10, add the digit terms of the numbers, and if appropriate, convert\nthe digit term back to a number between 1 and 10 by adjusting the exponential term.\n"]], ["block_7", [" Adding Exponentials \n"]], ["block_8", ["Add 5.00\n10and 3.00\n10.\n"]], ["block_9", [" Solution \n"]], ["block_10", [" Subtraction of Exponentials \n"]], ["block_11", ["Convert all numbers to the same power of 10, take the difference of the digit terms, and if appropriate, convert\nthe digit term back to a number between 1 and 10 by adjusting the exponential term.\n"]], ["block_12", [" Subtracting Exponentials \n"]], ["block_13", ["Subtract 4.0\n10from 5.0\n10.\n"]], ["block_14", ["EXAMPLE B1\n"]], ["block_15", ["EXAMPLE B2\n"]], ["block_16", [" B \u2022 Essential Mathematics \n 1079 \n"]]], "page_1093": [["block_0", [" 1080 \n B \u2022 Essential Mathematics \n"]], ["block_1", [" Solution \n"]], ["block_2", [" Multiplication of Exponentials \n"]], ["block_3", ["Multiply the digit terms in the usual way and add the exponents of the exponential terms.\n"]], ["block_4", [" Multiplying Exponentials \n"]], ["block_5", ["Multiply 4.2\n10by 2.0\n10.\n"]], ["block_6", [" Solution \n"]], ["block_7", [" Division of Exponentials \n"]], ["block_8", ["Divide the digit term of the numerator by the digit term of the denominator and subtract the exponents of the\nexponential terms.\n"]], ["block_9", [" Dividing Exponentials \n"]], ["block_10", ["Divide 3.6\n10by 6.0\n10.\n"]], ["block_11", [" Solution \n"]], ["block_12", [" Squaring of Exponentials \n"]], ["block_13", ["Square the digit term in the usual way and multiply the exponent of the exponential term by 2.\n"]], ["block_14", [" Squaring Exponentials \n"]], ["block_15", ["Square the number 4.0\n10.\n"]], ["block_16", [" Solution \n"]], ["block_17", [" Cubing of Exponentials \n"]], ["block_18", ["Cube the digit term in the usual way and multiply the exponent of the exponential term by 3.\n"]], ["block_19", [" Access for free at openstax.org \n"]], ["block_20", ["EXAMPLE B3\n"]], ["block_21", ["EXAMPLE B4\n"]], ["block_22", ["EXAMPLE B5\n"]], ["block_23", ["EXAMPLE B6\n"]]], "page_1094": [["block_0", [" Cubing Exponentials \n"]], ["block_1", ["Cube the number 2\n10.\n"]], ["block_2", [" Solution \n"]], ["block_3", [" Taking Square Roots of Exponentials \n"]], ["block_4", ["If necessary, decrease or increase the exponential term so that the power of 10 is evenly divisible by 2. Extract\nthe square root of the digit term and divide the exponential term by 2.\n"]], ["block_5", [" Finding the Square Root of Exponentials \n"]], ["block_6", ["Find the square root of 1.6\n10.\n"]], ["block_7", [" Solution \n"]], ["block_8", [" Significant Figures \n"]], ["block_9", ["A beekeeper reports that he has 525,341 bees. The last three figures of the number are obviously inaccurate,\nfor during the time the keeper was counting the bees, some of them died and others hatched; this makes it\nquite difficult to determine the exact number of bees. It would have been more reasonable if the beekeeper had\nreported the number 525,000. In other words, the last three figures are not significant, except to set the\nposition of the decimal point. Their exact values have no useful meaning in this situation. When reporting\nquantities, use only as many significant figures as the accuracy of the measurement warrants.\n"]], ["block_10", ["The importance of significant figures lies in their application to fundamental computation. In addition and\nsubtraction, the sum or difference should contain as many digits to the right of the decimal as that in the least\ncertain of the numbers used in the computation (indicated by underscoring in the following example).\n"]], ["block_11", [" Addition and Subtraction with Significant Figures \n"]], ["block_12", ["Add 4.383 g and 0.0023 g.\n"]], ["block_13", [" Solution \n"]], ["block_14", ["In multiplication and division, the product or quotient should contain no more digits than that in the factor\ncontaining the least number of significant figures.\n"]], ["block_15", ["EXAMPLE B7\n"]], ["block_16", ["EXAMPLE B8\n"]], ["block_17", ["EXAMPLE B9\n"]], ["block_18", [" B \u2022 Essential Mathematics \n 1081 \n"]]], "page_1095": [["block_0", ["To obtain the natural logarithm of a number, use the ln button on your calculator. To calculate a number from\nits natural logarithm, enter the natural logarithm and take the inverse ln of the natural logarithm, or calculate\ne(where x is the natural logarithm of the number).\n"]], ["block_1", [" 1082 \n B \u2022 Essential Mathematics \n"]], ["block_2", [" Multiplication and Division with Significant Figures \n"]], ["block_3", ["Multiply 0.6238 by 6.6.\n"]], ["block_4", [" Solution \n"]], ["block_5", ["When rounding numbers, increase the retained digit by 1 if it is followed by a number larger than 5 (\u201cround\nup\u201d). Do not change the retained digit if the digits that follow are less than 5 (\u201cround down\u201d). If the retained\ndigit is followed by 5, round up if the retained digit is odd, or round down if it is even (after rounding, the\nretained digit will thus always be even).\n"]], ["block_6", [" The Use of Logarithms and Exponential Numbers \n"]], ["block_7", ["The common logarithm of a number (log) is the power to which 10 must be raised to equal that number. For\nexample, the common logarithm of 100 is 2, because 10 must be raised to the second power to equal 100.\nAdditional examples follow.\n"]], ["block_8", ["What is the common logarithm of 60? Because 60 lies between 10 and 100, which have logarithms of 1 and 2,\nrespectively, the logarithm of 60 is 1.7782; that is,\n"]], ["block_9", ["The common logarithm of a number less than 1 has a negative value. The logarithm of 0.03918 is \u22121.4069, or\n"]], ["block_10", ["To obtain the common logarithm of a number, use the log button on your calculator. To calculate a number\nfrom its logarithm, take the inverse log of the logarithm, or calculate 10(where x is the logarithm of the\nnumber).\n"]], ["block_11", ["The natural logarithm of a number (ln) is the power to which e must be raised to equal the number; e is the\nconstant 2.7182818. For example, the natural logarithm of 10 is 2.303; that is,\n"]], ["block_12", ["Logarithms are exponents; thus, operations involving logarithms follow the same rules as operations involving\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", [" TABLE B1 \n"]], ["block_15", [" Number \n Number Expressed Exponentially\n Common Logarithm \n"]], ["block_16", ["1000\n10\n3\n"]], ["block_17", ["10\n10\n1\n"]], ["block_18", ["1\n10\n0\n"]], ["block_19", ["0.1\n10\n\u22121\n"]], ["block_20", ["0.001\n10\n\u22123\n"]], ["block_21", ["Logarithms and Exponential Numbers\n"]]], "page_1096": [["block_0", ["When the value of y is changing as a function of x (that is, different values of x correspond to different values of\ny), a graph of this change can be plotted or sketched. The graph can be produced by using specific values for\n(x,y) data pairs.\n"]], ["block_1", ["exponents.\n"]], ["block_2", [" The Solution of Quadratic Equations \n"]], ["block_3", ["Mathematical functions of this form are known as second-order polynomials or, more commonly, quadratic\nfunctions.\n"]], ["block_4", ["The solution or roots for any quadratic equation can be calculated using the following formula:\n"]], ["block_5", [" Solving Quadratic Equations \n"]], ["block_6", ["Solve the quadratic equation 3x+ 13x \u2212 10 = 0.\n"]], ["block_7", [" Solution \n"]], ["block_8", ["Substituting the values a = 3, b = 13, c = \u221210 in the formula, we obtain\n"]], ["block_9", ["The two roots are therefore\n"]], ["block_10", ["Quadratic equations constructed on physical data always have real roots, and of these real roots, often only\nthose having positive values are of any significance.\n"]], ["block_11", [" Two-Dimensional (x-y) Graphing \n"]], ["block_12", ["The relationship between any two properties of a system can be represented graphically by a two-dimensional\ndata plot. Such a graph has two axes: a horizontal one corresponding to the independent variable, or the\nvariable whose value is being controlled (x), and a vertical axis corresponding to the dependent variable, or the\nvariable whose value is being observed or measured (y).\n"]], ["block_13", ["1.\nThe logarithm of a product of two numbers is the sum of the logarithms of the two numbers.\n"]], ["block_14", ["2.\nThe logarithm of the number resulting from the division of two numbers is the difference between the\nlogarithms of the two numbers.\n"]], ["block_15", ["3.\nThe logarithm of a number raised to an exponent is the product of the exponent and the logarithm of the\nnumber.\n"]], ["block_16", ["EXAMPLE B10\n"]], ["block_17", ["EXAMPLE B11\n"]], ["block_18", [" B \u2022 Essential Mathematics \n 1083 \n"]]], "page_1097": [["block_0", [" 1084 \n B \u2022 Essential Mathematics \n"]], ["block_1", [" Graphing the Dependence of y on x \n"]], ["block_2", ["This table contains the following points: (1,5), (2,10), (3,7), and (4,14). Each of these points can be plotted on a\ngraph and connected to produce a graphical representation of the dependence of y on x.\n"]], ["block_3", [{"image_0": "1097_0.png", "coords": [72, 265, 432, 504]}]], ["block_4", ["If the function that describes the dependence of y on x is known, it may be used to compute x,y data pairs that\nmay subsequently be plotted.\n"]], ["block_5", [" Plotting Data Pairs \n"]], ["block_6", ["If we know that y = x+ 2, we can produce a table of a few (x,y) values and then plot the line based on the data\nshown here.\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", ["EXAMPLE B12\n"]], ["block_9", [" x \ny = x 2 + 2\n"]], ["block_10", ["1\n3\n"]], ["block_11", ["2\n6\n"]], ["block_12", [" x \n y \n"]], ["block_13", ["1\n5\n"]], ["block_14", ["2\n10\n"]], ["block_15", ["3\n7\n"]], ["block_16", ["4\n14\n"]]], "page_1098": [["block_0", [{"image_0": "1098_0.png", "coords": [72, 147, 432, 430]}]], ["block_1", [" x \ny = x 2 + 2\n"]], ["block_2", ["3\n11\n"]], ["block_3", ["4\n18\n"]], ["block_4", [" B \u2022 Essential Mathematics \n 1085 \n"]]], "page_1099": [["block_0", [" 1086 \n B \u2022 Essential Mathematics \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_1100": [["block_0", [" APPENDIX C \n"]], ["block_1", [" Units and Conversion Factors \n"]], ["block_2", [" TABLE C2 \n"]], ["block_3", ["liter (L)\n"]], ["block_4", ["milliliter (mL)\n= 0.001 L (exact, definition)\n= 1 cm(exact, definition)\n"]], ["block_5", ["microliter\n= 10L (exact, definition)\n= 10cm(exact, definition)\n"]], ["block_6", ["liquid quart (US)\n"]], ["block_7", ["dry quart\n= 1.1012 L\n"]], ["block_8", ["cubic foot (US)\n= 28.316 L\n"]], ["block_9", [" TABLE C1 \n"]], ["block_10", ["meter (m)\n= 39.37 inches (in.)\n= 1.094 yards (yd)\n"]], ["block_11", ["centimeter (cm)\n= 0.01 m (exact, definition)\n"]], ["block_12", ["millimeter (mm)\n= 0.001 m (exact, definition)\n"]], ["block_13", ["kilometer (km)\n= 1000 m (exact, definition)\n"]], ["block_14", ["angstrom (\u00c5)\n= 10cm (exact, definition)\n= 10m (exact, definition)\n"]], ["block_15", ["yard (yd)\n= 0.9144 m\n"]], ["block_16", ["inch (in.)\n= 2.54 cm (exact, definition)\n"]], ["block_17", ["mile (US)\n= 1.60934 km\n"]], ["block_18", ["= 0.001 m(exact, definition)\n= 1000 cm(exact, definition)\n= 1.057 (US) quarts\n"]], ["block_19", ["= 32 (US) liquid ounces (exact, definition)\n= 0.25 (US) gallon (exact, definition)\n= 0.9463 L\n"]], ["block_20", ["Units of Volume\n"]], ["block_21", ["Units of Length\n"]], ["block_22", [" C \u2022 Units and Conversion Factors \n 1087 \n"]]], "page_1101": [["block_0", [" 1088 \n C \u2022 Units and Conversion Factors \n"]], ["block_1", ["1 BTU is the amount of energy needed to heat one pound of water by one degree Fahrenheit. Therefore, the exact relationship of\nBTU to joules and other energy units depends on the temperature at which BTU is measured. 59 \u00b0F (15 \u00b0C) is the most widely used\nreference temperature for BTU definition in the United States. At this temperature, the conversion factor is the one provided in this\ntable.\n"]], ["block_2", [" Access for free at openstax.org \n"]], ["block_3", [" TABLE C4 \n"]], ["block_4", ["4.184 joule (J)\n= 1 thermochemical calorie (cal)\n"]], ["block_5", ["1 thermochemical calorie (cal)\n= 4.184\n10erg\n"]], ["block_6", ["erg\n= 10J (exact, definition)\n"]], ["block_7", ["electron-volt (eV)\n= 1.60218\n10J = 23.061 kcal mol\n"]], ["block_8", ["liter\u2219atmosphere\n= 24.217 cal = 101.325 J (exact, definition)\n"]], ["block_9", ["nutritional calorie (Cal)\n= 1000 cal (exact, definition) = 4184 J\n"]], ["block_10", ["British thermal unit (BTU)\n= 1054.804 J\n"]], ["block_11", [" TABLE C5 \n"]], ["block_12", ["torr\n= 1 mm Hg (exact, definition)\n"]], ["block_13", [" TABLE C3 \n"]], ["block_14", ["gram (g)\n= 0.001 kg (exact, definition)\n"]], ["block_15", ["milligram (mg)\n= 0.001 g (exact, definition)\n"]], ["block_16", ["kilogram (kg)\n= 1000 g (exact, definition)\n= 2.205 lb\n"]], ["block_17", ["ton (metric)\n=1000 kg (exact, definition)\n= 2204.62 lb\n"]], ["block_18", ["ounce (oz)\n= 28.35 g\n"]], ["block_19", ["pound (lb)\n= 0.4535924 kg\n"]], ["block_20", ["ton (short)\n=2000 lb (exact, definition)\n= 907.185 kg\n"]], ["block_21", ["ton (long)\n= 2240 lb (exact, definition)\n= 1.016 metric ton\n"]], ["block_22", ["Units of Pressure\n"]], ["block_23", ["Units of Energy\n"]], ["block_24", ["Units of Mass\n"]]], "page_1102": [["block_0", [" TABLE C5 \n"]], ["block_1", ["pascal (Pa)\n= N m(exact, definition)\n= kg ms(exact, definition)\n"]], ["block_2", ["atmosphere (atm)\n"]], ["block_3", ["bar\n= 10Pa (exact, definition)\n= 10kg ms(exact, definition)\n"]], ["block_4", ["= 760 mm Hg (exact, definition)\n= 760 torr (exact, definition)\n= 101,325 N m(exact, definition)\n= 101,325 Pa (exact, definition)\n"]], ["block_5", [" C \u2022 Units and Conversion Factors \n 1089 \n"]]], "page_1103": [["block_0", [" 1090 \n C \u2022 Units and Conversion Factors \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_1104": [["block_0", [" APPENDIX D \n"]], ["block_1", ["Fundamental Physical Constants\n"]], ["block_2", [" TABLE D1 \n"]], ["block_3", [" Name and Symbol \n Value \n"]], ["block_4", ["atomic mass unit (amu)\n1.6605402\n10kg\n"]], ["block_5", ["Avogadro\u2019s number\n6.02214076\n10mol\n"]], ["block_6", ["Boltzmann\u2019s constant (k)\n1.380649\n10J K\n"]], ["block_7", ["charge-to-mass ratio for electron (e/me)\n1.75881962\n10C kg\n"]], ["block_8", ["fundamental unit of charge (e)\n1.602176634\n10C\n"]], ["block_9", ["electron rest mass (me)\n9.1093897\n10kg\n"]], ["block_10", ["Faraday\u2019s constant (F)\n9.6485309\n10C mol\n"]], ["block_11", ["gas constant (R)\n8.205784\n10L atm molK= 8.314510 J molK\n"]], ["block_12", ["molar volume of an ideal gas, 1 atm, 0 \u00b0C\n22.41409 L mol\n"]], ["block_13", ["molar volume of an ideal gas, 1 bar, 0 \u00b0C\n22.71108 L mol\n"]], ["block_14", ["neutron rest mass (mn)\n1.6749274\n10kg\n"]], ["block_15", ["Planck\u2019s constant (h)\n6.62607015\n10J s\n"]], ["block_16", ["proton rest mass (mp)\n1.6726231\n10kg\n"]], ["block_17", ["Rydberg constant (R)\n1.0973731534\n10m= 2.1798736\n10J\n"]], ["block_18", ["speed of light (in vacuum) (c)\n2.99792458\n10m s\n"]], ["block_19", ["Fundamental Physical Constants\n"]], ["block_20", [" D \u2022 Fundamental Physical Constants \n 1091 \n"]]], "page_1105": [["block_0", [" 1092 \n D \u2022 Fundamental Physical Constants \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_1106": [["block_0", [" APPENDIX E \n"]], ["block_1", [" Water Properties \n"]], ["block_2", [" TABLE E1 \n"]], ["block_3", ["Water Density (g/mL) at Different Temperatures (\u00b0C)\n"]], ["block_4", [" Temperature \n Density (g/mL) \n"]], ["block_5", ["0\n0.9998395\n"]], ["block_6", ["4\n0.9999720 (density maximum)\n"]], ["block_7", ["10\n0.9997026\n"]], ["block_8", ["15\n0.9991026\n"]], ["block_9", ["20\n0.9982071\n"]], ["block_10", ["22\n0.9977735\n"]], ["block_11", ["25\n0.9970479\n"]], ["block_12", ["30\n0.9956502\n"]], ["block_13", ["40\n0.9922\n"]], ["block_14", ["60\n0.9832\n"]], ["block_15", ["80\n0.9718\n"]], ["block_16", ["100\n0.9584\n"]], ["block_17", [" E \u2022 Water Properties \n 1093 \n"]]], "page_1107": [["block_0", [" 1094 \n E \u2022 Water Properties \n"]], ["block_1", [{"image_0": "1107_0.png", "coords": [72, 57, 423, 308]}]], ["block_2", [" Access for free at openstax.org \n"]], ["block_3", [" TABLE E2 \n"]], ["block_4", [" Temperature \n Vapor Pressure (torr) \n Vapor Pressure (Pa) \n"]], ["block_5", ["0\n4.6\n613.2812\n"]], ["block_6", ["4\n6.1\n813.2642\n"]], ["block_7", ["10\n9.2\n1226.562\n"]], ["block_8", ["15\n12.8\n1706.522\n"]], ["block_9", ["20\n17.5\n2333.135\n"]], ["block_10", ["22\n19.8\n2639.776\n"]], ["block_11", ["25\n23.8\n3173.064\n"]], ["block_12", ["30\n31.8\n4239.64\n"]], ["block_13", ["35\n42.2\n5626.188\n"]], ["block_14", ["40\n55.3\n7372.707\n"]], ["block_15", ["45\n71.9\n9585.852\n"]], ["block_16", ["50\n92.5\n12332.29\n"]], ["block_17", ["55\n118.0\n15732\n"]], ["block_18", ["Water Vapor Pressure at Different Temperatures (\u00b0C)\n"]]], "page_1108": [["block_0", [{"image_0": "1108_0.png", "coords": [72, 346, 423, 611]}]], ["block_1", ["1 pKw = \u2013log10(Kw)\n"]], ["block_2", [" TABLE E2 \n"]], ["block_3", [" Temperature \n Vapor Pressure (torr) \n Vapor Pressure (Pa) \n"]], ["block_4", ["60\n149.4\n19918.31\n"]], ["block_5", ["65\n187.5\n24997.88\n"]], ["block_6", ["70\n233.7\n31157.35\n"]], ["block_7", ["75\n289.1\n38543.39\n"]], ["block_8", ["80\n355.1\n47342.64\n"]], ["block_9", ["85\n433.6\n57808.42\n"]], ["block_10", ["90\n525.8\n70100.71\n"]], ["block_11", ["95\n633.9\n84512.82\n"]], ["block_12", ["100\n760.0\n101324.7\n"]], ["block_13", [" TABLE E3 \n"]], ["block_14", ["Water Kw and pKw at Different Temperatures (\u00b0C)\n"]], ["block_15", [" Temperature \n K w 10 \u201314 \n pK w \n"]], ["block_16", ["0\n0.112\n14.95\n"]], ["block_17", [" 1 \n"]], ["block_18", [" E \u2022 Water Properties \n 1095 \n"]]], "page_1109": [["block_0", [" 1096 \n E \u2022 Water Properties \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE E3 \n"]], ["block_3", [" Temperature \n K w 10 \u201314 \n pK w \n"]], ["block_4", ["5\n0.182\n14.74\n"]], ["block_5", ["10\n0.288\n14.54\n"]], ["block_6", ["15\n0.465\n14.33\n"]], ["block_7", ["20\n0.671\n14.17\n"]], ["block_8", ["25\n0.991\n14.00\n"]], ["block_9", ["30\n1.432\n13.84\n"]], ["block_10", ["35\n2.042\n13.69\n"]], ["block_11", ["40\n2.851\n13.55\n"]], ["block_12", ["45\n3.917\n13.41\n"]], ["block_13", ["50\n5.297\n13.28\n"]], ["block_14", ["55\n7.080\n13.15\n"]], ["block_15", ["60\n9.311\n13.03\n"]], ["block_16", ["75\n19.95\n12.70\n"]], ["block_17", ["100\n56.23\n12.25\n"]], ["block_18", [" 1 \n"]]], "page_1110": [["block_0", [{"image_0": "1110_0.png", "coords": [72, 57, 423, 322]}]], ["block_1", [" TABLE E6 \n"]], ["block_2", ["Water Cryoscopic (Freezing Point Depression) and Ebullioscopic (Boiling Point Elevation) Constants\n"]], ["block_3", ["Kf = 1.86\u00b0C\u2219kg\u2219mol(cryoscopic constant)\n"]], ["block_4", ["Kb = 0.51\u00b0C\u2219kg\u2219mol(ebullioscopic constant)\n"]], ["block_5", [" TABLE E5 \n"]], ["block_6", ["Standard Water Melting and Boiling Temperatures and Enthalpies of the Transitions\n"]], ["block_7", ["melting\n273.15\n6.088\n"]], ["block_8", ["boiling\n373.15\n40.656 (44.016 at 298 K)\n"]], ["block_9", [" Temperature (K) \n \u0394H (kJ/mol) \n"]], ["block_10", [" TABLE E4 \n"]], ["block_11", ["Specific Heat Capacity for Water\n"]], ["block_12", ["C\u00b0(H2O(l)) = 4.184 J\u2219g\u2219\u00b0C\n"]], ["block_13", ["C\u00b0(H2O(s)) = 1.864 J\u2219K\u2219g\n"]], ["block_14", ["C\u00b0(H2O(g)) = 2.093 J\u2219K\u2219g\n"]], ["block_15", [" E \u2022 Water Properties \n 1097 \n"]]], "page_1111": [["block_0", [" 1098 \n E \u2022 Water Properties \n"]], ["block_1", [{"image_0": "1111_0.png", "coords": [72, 57, 540, 369]}]], ["block_2", [" FIGURE E1 \nThe plot shows the extent of light absorption versus wavelength for water. Absorption is reported in\n"]], ["block_3", ["reciprocal meters and corresponds to the inverse of the distance light may travel through water before its intensity\nis diminished by 1/e (~37%).\n"]], ["block_4", [" Access for free at openstax.org \n"]]], "page_1112": [["block_0", [" APPENDIX F \n"]], ["block_1", ["Composition of Commercial Acids and Bases\n"]], ["block_2", ["1 Acids and bases are commercially available as aqueous solutions. This table lists properties (densities and concentrations) of\ncommon acid and base solutions. Nominal values are provided in cases where the manufacturer cites a range of concentrations and\ndensities.\n2 This column contains specific gravity data. In the case of this table, specific gravity is the ratio of density of a substance to the\ndensity of pure water at the same conditions. Specific gravity is often cited on commercial labels.\n3 This solution is sometimes called \u201cammonium hydroxide,\u201d although this term is not chemically accurate.\n"]], ["block_3", [" TABLE F1 \n"]], ["block_4", [" Acid or Base 1 \n Density (g/mL) 2 \n Percentage by Mass \n Molarity \n"]], ["block_5", ["acetic acid, glacial\n1.05\n99.5%\n17.4\n"]], ["block_6", ["aqueous ammonia\n0.90\n28%\n14.8\n"]], ["block_7", ["hydrochloric acid\n1.18\n36%\n11.6\n"]], ["block_8", ["nitric acid\n1.42\n71%\n16.0\n"]], ["block_9", ["perchloric acid\n1.67\n70%\n11.65\n"]], ["block_10", ["phosphoric acid\n1.70\n85%\n14.7\n"]], ["block_11", ["sodium hydroxide\n1.53\n50%\n19.1\n"]], ["block_12", ["sulfuric acid\n1.84\n96%\n18.0\n"]], ["block_13", ["Composition of Commercial Acids and Bases\n"]], ["block_14", [" F \u2022 Composition of Commercial Acids and Bases \n 1099 \n"]]], "page_1113": [["block_0", [" 1100 \n F \u2022 Composition of Commercial Acids and Bases \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_1114": [["block_0", [" APPENDIX G \n"]], ["block_1", ["Standard Thermodynamic Properties for Selected Substances\n"]], ["block_2", [" TABLE G1 \n"]], ["block_3", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_4", ["aluminum\n"]], ["block_5", ["Al(s)\n0\n0\n28.3\n"]], ["block_6", ["Al(g)\n324.4\n285.7\n164.54\n"]], ["block_7", ["Al(aq)\n\u2013531\n\u2013485\n\u2013321.7\n"]], ["block_8", ["Al2O3(s)\n\u20131676\n\u20131582\n50.92\n"]], ["block_9", ["AlF3(s)\n\u20131510.4\n\u20131425\n66.5\n"]], ["block_10", ["AlCl3(s)\n\u2013704.2\n\u2013628.8\n110.67\n"]], ["block_11", ["AlCl3\u00b76H2O(s)\n\u20132691.57\n\u20132269.40\n376.56\n"]], ["block_12", ["Al2S3(s)\n\u2013724.0\n\u2013492.4\n116.9\n"]], ["block_13", ["Al2(SO4)3(s)\n\u20133445.06\n\u20133506.61\n239.32\n"]], ["block_14", ["antimony\n"]], ["block_15", ["Sb(s)\n0\n0\n45.69\n"]], ["block_16", ["Sb(g)\n262.34\n222.17\n180.16\n"]], ["block_17", ["Sb4O6(s)\n\u20131440.55\n\u20131268.17\n220.92\n"]], ["block_18", ["SbCl3(g)\n\u2013313.8\n\u2013301.2\n337.80\n"]], ["block_19", ["SbCl5(g)\n\u2013394.34\n\u2013334.29\n401.94\n"]], ["block_20", ["Sb2S3(s)\n\u2013174.89\n\u2013173.64\n182.00\n"]], ["block_21", ["SbCl3(s)\n\u2013382.17\n\u2013323.72\n184.10\n"]], ["block_22", ["SbOCl(s)\n\u2013374.0\n\u2014\n\u2014\n"]], ["block_23", ["Standard Thermodynamic Properties for Selected Substances\n"]], ["block_24", [" G \u2022 Standard Thermodynamic Properties for Selected Substances \n 1101 \n"]]], "page_1115": [["block_0", [" 1102 \n G \u2022 Standard Thermodynamic Properties for Selected Substances \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE G1 \n"]], ["block_3", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_4", ["arsenic\n"]], ["block_5", ["As(s)\n0\n0\n35.1\n"]], ["block_6", ["As(g)\n302.5\n261.0\n174.21\n"]], ["block_7", ["As4(g)\n143.9\n92.4\n314\n"]], ["block_8", ["As4O6(s)\n\u20131313.94\n\u20131152.52\n214.22\n"]], ["block_9", ["As2O5(s)\n\u2013924.87\n\u2013782.41\n105.44\n"]], ["block_10", ["AsCl3(g)\n\u2013261.50\n\u2013248.95\n327.06\n"]], ["block_11", ["As2S3(s)\n\u2013169.03\n\u2013168.62\n163.59\n"]], ["block_12", ["AsH3(g)\n66.44\n68.93\n222.78\n"]], ["block_13", ["H3AsO4(s)\n\u2013906.3\n\u2014\n\u2014\n"]], ["block_14", ["barium\n"]], ["block_15", ["Ba(s)\n0\n0\n62.5\n"]], ["block_16", ["Ba(g)\n180\n146\n170.24\n"]], ["block_17", ["Ba(aq)\n\u2013537.6\n\u2013560.8\n9.6\n"]], ["block_18", ["BaO(s)\n\u2013548.0\n\u2013520.3\n72.1\n"]], ["block_19", ["BaCl2(s)\n\u2013855.0\n\u2013806.7\n123.7\n"]], ["block_20", ["BaSO4(s)\n\u20131473.2\n\u20131362.3\n132.2\n"]], ["block_21", ["beryllium\n"]], ["block_22", ["Be(s)\n0\n0\n9.50\n"]], ["block_23", ["Be(g)\n324.3\n286.6\n136.27\n"]], ["block_24", ["BeO(s)\n\u2013609.4\n\u2013580.1\n13.8\n"]], ["block_25", ["bismuth\n"]], ["block_26", ["Bi(s)\n0\n0\n56.74\n"]], ["block_27", ["Bi(g)\n207.1\n168.2\n187.00\n"]]], "page_1116": [["block_0", [" TABLE G1 \n"]], ["block_1", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_2", ["Bi2O3(s)\n\u2013573.88\n\u2013493.7\n151.5\n"]], ["block_3", ["BiCl3(s)\n\u2013379.07\n\u2013315.06\n176.98\n"]], ["block_4", ["Bi2S3(s)\n\u2013143.1\n\u2013140.6\n200.4\n"]], ["block_5", ["boron\n"]], ["block_6", ["B(s)\n0\n0\n5.86\n"]], ["block_7", ["B(g)\n565.0\n521.0\n153.4\n"]], ["block_8", ["B2O3(s)\n\u20131273.5\n\u20131194.3\n53.97\n"]], ["block_9", ["B2H6(g)\n36.4\n87.6\n232.1\n"]], ["block_10", ["H3BO3(s)\n\u20131094.33\n\u2013968.92\n88.83\n"]], ["block_11", ["BF3(g)\n\u20131136.0\n\u20131119.4\n254.4\n"]], ["block_12", ["BCl3(g)\n\u2013403.8\n\u2013388.7\n290.1\n"]], ["block_13", ["B3N3H6(l)\n\u2013540.99\n\u2013392.79\n199.58\n"]], ["block_14", ["HBO2(s)\n\u2013794.25\n\u2013723.41\n37.66\n"]], ["block_15", ["bromine\n"]], ["block_16", ["Br2(l)\n0\n0\n152.23\n"]], ["block_17", ["Br2(g)\n30.91\n3.142\n245.5\n"]], ["block_18", ["Br(g)\n111.88\n82.429\n175.0\n"]], ["block_19", ["Br(aq)\n\u2013120.9\n\u2013102.82\n80.71\n"]], ["block_20", ["BrF3(g)\n\u2013255.60\n\u2013229.45\n292.42\n"]], ["block_21", ["HBr(g)\n\u201336.3\n\u201353.43\n198.7\n"]], ["block_22", ["cadmium\n"]], ["block_23", ["Cd(s)\n0\n0\n51.76\n"]], ["block_24", ["Cd(g)\n112.01\n77.41\n167.75\n"]], ["block_25", ["Cd(aq)\n\u201375.90\n\u201377.61\n\u201373.2\n"]], ["block_26", [" G \u2022 Standard Thermodynamic Properties for Selected Substances \n 1103 \n"]]], "page_1117": [["block_0", [" 1104 \n G \u2022 Standard Thermodynamic Properties for Selected Substances \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE G1 \n"]], ["block_3", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_4", ["CdO(s)\n\u2013258.2\n\u2013228.4\n54.8\n"]], ["block_5", ["CdCl2(s)\n\u2013391.5\n\u2013343.9\n115.3\n"]], ["block_6", ["CdSO4(s)\n\u2013933.3\n\u2013822.7\n123.0\n"]], ["block_7", ["CdS(s)\n\u2013161.9\n\u2013156.5\n64.9\n"]], ["block_8", ["calcium\n"]], ["block_9", ["Ca(s)\n0\n0\n41.6\n"]], ["block_10", ["Ca(g)\n178.2\n144.3\n154.88\n"]], ["block_11", ["Ca(aq)\n\u2013542.96\n\u2013553.04\n\u201355.2\n"]], ["block_12", ["CaO(s)\n\u2013634.9\n\u2013603.3\n38.1\n"]], ["block_13", ["Ca(OH)2(s)\n\u2013985.2\n\u2013897.5\n83.4\n"]], ["block_14", ["CaSO4(s)\n\u20131434.5\n\u20131322.0\n106.5\n"]], ["block_15", ["CaSO4\u00b72H2O(s)\n\u20132022.63\n\u20131797.45\n194.14\n"]], ["block_16", ["CaCO3(s) (calcite)\n\u20131220.0\n\u20131081.4\n110.0\n"]], ["block_17", ["CaSO3\u00b7H2O(s)\n\u20131752.68\n\u20131555.19\n184.10\n"]], ["block_18", ["carbon\n"]], ["block_19", ["C(s) (graphite)\n0\n0\n5.740\n"]], ["block_20", ["C(s) (diamond)\n1.89\n2.90\n2.38\n"]], ["block_21", ["C(g)\n716.681\n671.2\n158.1\n"]], ["block_22", ["CO(g)\n\u2013110.52\n\u2013137.15\n197.7\n"]], ["block_23", ["CO2(g)\n\u2013393.51\n\u2013394.36\n213.8\n"]], ["block_24", ["CO3 (aq)\n\u2013677.1\n\u2013527.8\n\u201356.9\n"]], ["block_25", ["CH4(g)\n\u201374.6\n\u201350.5\n186.3\n"]], ["block_26", ["CH3OH(l)\n\u2013239.2\n\u2013166.6\n126.8\n"]], ["block_27", ["CH3OH(g)\n\u2013201.0\n\u2013162.3\n239.9\n"]]], "page_1118": [["block_0", [" TABLE G1 \n"]], ["block_1", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_2", ["CCl4(l)\n\u2013128.2\n\u201362.5\n214.4\n"]], ["block_3", ["CCl4(g)\n\u201395.7\n\u201358.2\n309.7\n"]], ["block_4", ["CHCl3(l)\n\u2013134.1\n\u201373.7\n201.7\n"]], ["block_5", ["CHCl3(g)\n\u2013103.14\n\u201370.34\n295.71\n"]], ["block_6", ["CS2(l)\n89.70\n65.27\n151.34\n"]], ["block_7", ["CS2(g)\n116.9\n66.8\n238.0\n"]], ["block_8", ["C2H2(g)\n227.4\n209.2\n200.9\n"]], ["block_9", ["C2H4(g)\n52.4\n68.4\n219.3\n"]], ["block_10", ["C2H6(g)\n\u201384.0\n\u201332.0\n229.2\n"]], ["block_11", ["CH3CO2H(l)\n\u2013484.3\n\u2013389.9\n159.8\n"]], ["block_12", ["CH3CO2H(g)\n\u2013434.84\n\u2013376.69\n282.50\n"]], ["block_13", ["C2H5OH(l)\n\u2013277.6\n\u2013174.8\n160.7\n"]], ["block_14", ["C2H5OH(g)\n\u2013234.8\n\u2013167.9\n281.6\n"]], ["block_15", ["HCO3 (aq)\n\u2013691.11\n\u2013587.06\n95\n"]], ["block_16", ["C3H8(g)\n\u2013103.8\n\u201323.4\n270.3\n"]], ["block_17", ["C6H6(g)\n82.927\n129.66\n269.2\n"]], ["block_18", ["C6H6(l)\n49.1\n124.50\n173.4\n"]], ["block_19", ["CH2Cl2(l)\n\u2013124.2\n\u201363.2\n177.8\n"]], ["block_20", ["CH2Cl2(g)\n\u201395.4\n\u201365.90\n270.2\n"]], ["block_21", ["CH3Cl(g)\n\u201381.9\n\u201360.2\n234.6\n"]], ["block_22", ["C2H5Cl(l)\n\u2013136.52\n\u201359.31\n190.79\n"]], ["block_23", ["C2H5Cl(g)\n\u2013112.17\n\u201360.39\n276.00\n"]], ["block_24", ["C2N2(g)\n308.98\n297.36\n241.90\n"]], ["block_25", ["HCN(l)\n108.9\n125.0\n112.8\n"]], ["block_26", [" G \u2022 Standard Thermodynamic Properties for Selected Substances \n 1105 \n"]]], "page_1119": [["block_0", [" 1106 \n G \u2022 Standard Thermodynamic Properties for Selected Substances \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE G1 \n"]], ["block_3", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_4", ["HCN(g)\n135.5\n124.7\n201.8\n"]], ["block_5", ["cesium\n"]], ["block_6", ["Cs(aq)\n\u2013248\n\u2013282.0\n133\n"]], ["block_7", ["chlorine\n"]], ["block_8", ["Cl2(g)\n0\n0\n223.1\n"]], ["block_9", ["Cl(g)\n121.3\n105.70\n165.2\n"]], ["block_10", ["Cl(aq)\n\u2013167.2\n\u2013131.2\n56.5\n"]], ["block_11", ["ClF(g)\n\u201354.48\n\u201355.94\n217.78\n"]], ["block_12", ["ClF3(g)\n\u2013158.99\n\u2013118.83\n281.50\n"]], ["block_13", ["Cl2O(g)\n80.3\n97.9\n266.2\n"]], ["block_14", ["Cl2O7(l)\n238.1\n\u2014\n\u2014\n"]], ["block_15", ["Cl2O7(g)\n272.0\n\u2014\n\u2014\n"]], ["block_16", ["HCl(g)\n\u201392.307\n\u201395.299\n186.9\n"]], ["block_17", ["HClO4(l)\n\u201340.58\n\u2014\n\u2014\n"]], ["block_18", ["chromium\n"]], ["block_19", ["Cr(s)\n0\n0\n23.77\n"]], ["block_20", ["Cr(g)\n396.6\n351.8\n174.50\n"]], ["block_21", ["CrO4 (aq)\n\u2013881.2\n\u2013727.8\n50.21\n"]], ["block_22", ["Cr2O7 (aq)\n\u20131490.3\n\u20131301.1\n261.9\n"]], ["block_23", ["Cr2O3(s)\n\u20131139.7\n\u20131058.1\n81.2\n"]], ["block_24", ["CrO3(s)\n\u2013589.5\n\u2014\n\u2014\n"]], ["block_25", ["(NH4)2Cr2O7(s)\n\u20131806.7\n\u2014\n\u2014\n"]], ["block_26", ["cobalt\n"]], ["block_27", ["Co(s)\n0\n0\n30.0\n"]]], "page_1120": [["block_0", [" TABLE G1 \n"]], ["block_1", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_2", ["Co(aq)\n\u201367.4\n\u201351.5\n\u2013155\n"]], ["block_3", ["Co(aq)\n92\n134\n\u2013305.0\n"]], ["block_4", ["CoO(s)\n\u2013237.9\n\u2013214.2\n52.97\n"]], ["block_5", ["Co3O4(s)\n\u2013910.02\n\u2013794.98\n114.22\n"]], ["block_6", ["Co(NO3)2(s)\n\u2013420.5\n\u2014\n\u2014\n"]], ["block_7", ["copper\n"]], ["block_8", ["Cu(s)\n0\n0\n33.15\n"]], ["block_9", ["Cu(g)\n338.32\n298.58\n166.38\n"]], ["block_10", ["Cu(aq)\n51.9\n50.2\n\u201326\n"]], ["block_11", ["Cu(aq)\n64.77\n65.49\n\u201399.6\n"]], ["block_12", ["CuO(s)\n\u2013157.3\n\u2013129.7\n42.63\n"]], ["block_13", ["Cu2O(s)\n\u2013168.6\n\u2013146.0\n93.14\n"]], ["block_14", ["CuS(s)\n\u201353.1\n\u201353.6\n66.5\n"]], ["block_15", ["Cu2S(s)\n\u201379.5\n\u201386.2\n120.9\n"]], ["block_16", ["CuSO4(s)\n\u2013771.36\n\u2013662.2\n109.2\n"]], ["block_17", ["Cu(NO3)2(s)\n\u2013302.9\n\u2014\n\u2014\n"]], ["block_18", ["fluorine\n"]], ["block_19", ["F2(g)\n0\n0\n202.8\n"]], ["block_20", ["F(g)\n79.4\n62.3\n158.8\n"]], ["block_21", ["F(aq)\n\u2013332.6\n\u2013278.8\n\u201313.8\n"]], ["block_22", ["F2O(g)\n24.7\n41.9\n247.43\n"]], ["block_23", ["HF(g)\n\u2013273.3\n\u2013275.4\n173.8\n"]], ["block_24", ["hydrogen\n"]], ["block_25", ["H2(g)\n0\n0\n130.7\n"]], ["block_26", [" G \u2022 Standard Thermodynamic Properties for Selected Substances \n 1107 \n"]]], "page_1121": [["block_0", [" 1108 \n G \u2022 Standard Thermodynamic Properties for Selected Substances \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE G1 \n"]], ["block_3", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_4", ["H(g)\n217.97\n203.26\n114.7\n"]], ["block_5", ["H(aq)\n0\n0\n0\n"]], ["block_6", ["OH(aq)\n\u2013230.0\n\u2013157.2\n\u201310.75\n"]], ["block_7", ["H3O(aq)\n\u2013285.8\n69.91\n"]], ["block_8", ["H2O(l)\n\u2013285.83\n\u2013237.1\n70.0\n"]], ["block_9", ["H2O(g)\n\u2013241.82\n\u2013228.59\n188.8\n"]], ["block_10", ["H2O2(l)\n\u2013187.78\n\u2013120.35\n109.6\n"]], ["block_11", ["H2O2(g)\n\u2013136.3\n\u2013105.6\n232.7\n"]], ["block_12", ["HF(g)\n\u2013273.3\n\u2013275.4\n173.8\n"]], ["block_13", ["HCl(g)\n\u201392.307\n\u201395.299\n186.9\n"]], ["block_14", ["HBr(g)\n\u201336.3\n\u201353.43\n198.7\n"]], ["block_15", ["HI(g)\n26.48\n1.70\n206.59\n"]], ["block_16", ["H2S(g)\n\u201320.6\n\u201333.4\n205.8\n"]], ["block_17", ["H2Se(g)\n29.7\n15.9\n219.0\n"]], ["block_18", ["HNO3\n\u2013206.64\n\u2014\n\u2014\n"]], ["block_19", ["iodine\n"]], ["block_20", ["I2(s)\n0\n0\n116.14\n"]], ["block_21", ["I2(g)\n62.438\n19.3\n260.7\n"]], ["block_22", ["I(g)\n106.84\n70.2\n180.8\n"]], ["block_23", ["I(aq)\n\u201355.19\n\u201351.57\n11.13\n"]], ["block_24", ["IF(g)\n95.65\n\u2013118.49\n236.06\n"]], ["block_25", ["ICl(g)\n17.78\n\u20135.44\n247.44\n"]], ["block_26", ["IBr(g)\n40.84\n3.72\n258.66\n"]], ["block_27", ["IF7(g)\n\u2013943.91\n\u2013818.39\n346.44\n"]]], "page_1122": [["block_0", [" TABLE G1 \n"]], ["block_1", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_2", ["HI(g)\n26.48\n1.70\n206.59\n"]], ["block_3", ["iron\n"]], ["block_4", ["Fe(s)\n0\n0\n27.3\n"]], ["block_5", ["Fe(g)\n416.3\n370.7\n180.5\n"]], ["block_6", ["Fe(aq)\n\u201389.1\n\u201378.90\n\u2013137.7\n"]], ["block_7", ["Fe(aq)\n\u201348.5\n\u20134.7\n\u2013315.9\n"]], ["block_8", ["Fe2O3(s)\n\u2013824.2\n\u2013742.2\n87.40\n"]], ["block_9", ["Fe3O4(s)\n\u20131118.4\n\u20131015.4\n146.4\n"]], ["block_10", ["Fe(CO)5(l)\n\u2013774.04\n\u2013705.42\n338.07\n"]], ["block_11", ["Fe(CO)5(g)\n\u2013733.87\n\u2013697.26\n445.18\n"]], ["block_12", ["FeCl2(s)\n\u2013341.79\n\u2013302.30\n117.95\n"]], ["block_13", ["FeCl3(s)\n\u2013399.49\n\u2013334.00\n142.3\n"]], ["block_14", ["FeO(s)\n\u2013272.0\n\u2013255.2\n60.75\n"]], ["block_15", ["Fe(OH)2(s)\n\u2013569.0\n\u2013486.5\n88.\n"]], ["block_16", ["Fe(OH)3(s)\n\u2013823.0\n\u2013696.5\n106.7\n"]], ["block_17", ["FeS(s)\n\u2013100.0\n\u2013100.4\n60.29\n"]], ["block_18", ["Fe3C(s)\n25.10\n20.08\n104.60\n"]], ["block_19", ["lead\n"]], ["block_20", ["Pb(s)\n0\n0\n64.81\n"]], ["block_21", ["Pb(g)\n195.2\n162.\n175.4\n"]], ["block_22", ["Pb(aq)\n\u20131.7\n\u201324.43\n10.5\n"]], ["block_23", ["PbO(s) (yellow)\n\u2013217.32\n\u2013187.89\n68.70\n"]], ["block_24", ["PbO(s) (red)\n\u2013218.99\n\u2013188.93\n66.5\n"]], ["block_25", ["Pb(OH)2(s)\n\u2013515.9\n\u2014\n\u2014\n"]], ["block_26", [" G \u2022 Standard Thermodynamic Properties for Selected Substances \n 1109 \n"]]], "page_1123": [["block_0", [" 1110 \n G \u2022 Standard Thermodynamic Properties for Selected Substances \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE G1 \n"]], ["block_3", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_4", ["PbS(s)\n\u2013100.4\n\u201398.7\n91.2\n"]], ["block_5", ["Pb(NO3)2(s)\n\u2013451.9\n\u2014\n\u2014\n"]], ["block_6", ["PbO2(s)\n\u2013277.4\n\u2013217.3\n68.6\n"]], ["block_7", ["PbCl2(s)\n\u2013359.4\n\u2013314.1\n136.0\n"]], ["block_8", ["lithium\n"]], ["block_9", ["Li(s)\n0\n0\n29.1\n"]], ["block_10", ["Li(g)\n159.3\n126.6\n138.8\n"]], ["block_11", ["Li(aq)\n\u2013278.5\n\u2013293.3\n13.4\n"]], ["block_12", ["LiH(s)\n\u201390.5\n\u201368.3\n20.0\n"]], ["block_13", ["Li(OH)(s)\n\u2013487.5\n\u2013441.5\n42.8\n"]], ["block_14", ["LiF(s)\n\u2013616.0\n\u2013587.5\n35.7\n"]], ["block_15", ["Li2CO3(s)\n\u20131216.04\n\u20131132.19\n90.17\n"]], ["block_16", ["magnesium\n"]], ["block_17", ["Mg(aq)\n\u2013466.9\n\u2013454.8\n\u2013138.1\n"]], ["block_18", ["manganese\n"]], ["block_19", ["Mn(s)\n0\n0\n32.0\n"]], ["block_20", ["Mn(g)\n280.7\n238.5\n173.7\n"]], ["block_21", ["Mn(aq)\n\u2013220.8\n\u2013228.1\n\u201373.6\n"]], ["block_22", ["MnO(s)\n\u2013385.2\n\u2013362.9\n59.71\n"]], ["block_23", ["MnO2(s)\n\u2013520.03\n\u2013465.1\n53.05\n"]], ["block_24", ["Mn2O3(s)\n\u2013958.97\n\u2013881.15\n110.46\n"]], ["block_25", ["Mn3O4(s)\n\u20131378.83\n\u20131283.23\n155.64\n"]], ["block_26", ["MnO4 (aq)\n\u2013541.4\n\u2013447.2\n191.2\n"]], ["block_27", ["MnO4 (aq)\n\u2013653.0\n\u2013500.7\n59\n"]]], "page_1124": [["block_0", [" TABLE G1 \n"]], ["block_1", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_2", ["mercury\n"]], ["block_3", ["Hg(l)\n0\n0\n75.9\n"]], ["block_4", ["Hg(g)\n61.4\n31.8\n175.0\n"]], ["block_5", ["Hg(aq)\n164.8\n"]], ["block_6", ["Hg(aq)\n172.4\n153.9\n84.5\n"]], ["block_7", ["HgO(s) (red)\n\u201390.83\n\u201358.5\n70.29\n"]], ["block_8", ["HgO(s) (yellow)\n\u201390.46\n\u201358.43\n71.13\n"]], ["block_9", ["HgCl2(s)\n\u2013224.3\n\u2013178.6\n146.0\n"]], ["block_10", ["Hg2Cl2(s)\n\u2013265.4\n\u2013210.7\n191.6\n"]], ["block_11", ["HgS(s) (red)\n\u201358.16\n\u201350.6\n82.4\n"]], ["block_12", ["HgS(s) (black)\n\u201353.56\n\u201347.70\n88.28\n"]], ["block_13", ["HgSO4(s)\n\u2013707.51\n\u2013594.13\n0.00\n"]], ["block_14", ["nickel\n"]], ["block_15", ["Ni(aq)\n\u201364.0\n\u201346.4\n\u2013159\n"]], ["block_16", ["nitrogen\n"]], ["block_17", ["N2(g)\n0\n0\n191.6\n"]], ["block_18", ["N(g)\n472.704\n455.5\n153.3\n"]], ["block_19", ["NO(g)\n90.25\n87.6\n210.8\n"]], ["block_20", ["NO2(g)\n33.2\n51.30\n240.1\n"]], ["block_21", ["N2O(g)\n81.6\n103.7\n220.0\n"]], ["block_22", ["N2O3(g)\n83.72\n139.41\n312.17\n"]], ["block_23", ["NO3 (aq)\n\u2013205.0\n\u2013108.7\n146.4\n"]], ["block_24", ["N2O4(g)\n11.1\n99.8\n304.4\n"]], ["block_25", ["N2O5(g)\n11.3\n115.1\n355.7\n"]], ["block_26", [" G \u2022 Standard Thermodynamic Properties for Selected Substances \n 1111 \n"]]], "page_1125": [["block_0", [" 1112 \n G \u2022 Standard Thermodynamic Properties for Selected Substances \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE G1 \n"]], ["block_3", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_4", ["NH3(g)\n\u201345.9\n\u201316.5\n192.8\n"]], ["block_5", ["NH4 (aq)\n\u2013132.5\n\u201379.31\n113.4\n"]], ["block_6", ["N2H4(l)\n50.63\n149.43\n121.21\n"]], ["block_7", ["N2H4(g)\n95.4\n159.4\n238.5\n"]], ["block_8", ["NH4NO3(s)\n\u2013365.56\n\u2013183.87\n151.08\n"]], ["block_9", ["NH4Cl(s)\n\u2013314.43\n\u2013202.87\n94.6\n"]], ["block_10", ["NH4Br(s)\n\u2013270.8\n\u2013175.2\n113.0\n"]], ["block_11", ["NH4I(s)\n\u2013201.4\n\u2013112.5\n117.0\n"]], ["block_12", ["NH4NO2(s)\n\u2013256.5\n\u2014\n\u2014\n"]], ["block_13", ["HNO3(l)\n\u2013174.1\n\u201380.7\n155.6\n"]], ["block_14", ["HNO3(g)\n\u2013133.9\n\u201373.5\n266.9\n"]], ["block_15", ["HNO3(aq)\n\u2013207.4\n\u2013110.5\n146\n"]], ["block_16", ["oxygen\n"]], ["block_17", ["O2(g)\n0\n0\n205.2\n"]], ["block_18", ["O(g)\n249.17\n231.7\n161.1\n"]], ["block_19", ["O3(g)\n142.7\n163.2\n238.9\n"]], ["block_20", ["phosphorus\n"]], ["block_21", ["P4(s)\n0\n0\n164.4\n"]], ["block_22", ["P4(g)\n58.91\n24.4\n280.0\n"]], ["block_23", ["P(g)\n314.64\n278.25\n163.19\n"]], ["block_24", ["PH3(g)\n5.4\n13.5\n210.2\n"]], ["block_25", ["PCl3(g)\n\u2013287.0\n\u2013267.8\n311.78\n"]], ["block_26", ["PCl5(g)\n\u2013374.9\n\u2013305.0\n364.4\n"]], ["block_27", ["P4O6(s)\n\u20131640.1\n\u2014\n\u2014\n"]]], "page_1126": [["block_0", [" TABLE G1 \n"]], ["block_1", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_2", ["P4O10(s)\n\u20132984.0\n\u20132697.0\n228.86\n"]], ["block_3", ["PO4 (aq)\n\u20131277\n\u20131019\n\u2013222\n"]], ["block_4", ["HPO3(s)\n\u2013948.5\n\u2014\n\u2014\n"]], ["block_5", ["HPO4 (aq)\n\u20131292.1\n\u20131089.3\n\u201333\n"]], ["block_6", ["H2PO4 (aq)\n\u20131296.3\n\u20131130.4\n90.4\n"]], ["block_7", ["H3PO2(s)\n\u2013604.6\n\u2014\n\u2014\n"]], ["block_8", ["H3PO3(s)\n\u2013964.4\n\u2014\n\u2014\n"]], ["block_9", ["H3PO4(s)\n\u20131279.0\n\u20131119.1\n110.50\n"]], ["block_10", ["H3PO4(l)\n\u20131266.9\n\u20131124.3\n110.5\n"]], ["block_11", ["H4P2O7(s)\n\u20132241.0\n\u2014\n\u2014\n"]], ["block_12", ["POCl3(l)\n\u2013597.1\n\u2013520.8\n222.5\n"]], ["block_13", ["POCl3(g)\n\u2013558.5\n\u2013512.9\n325.5\n"]], ["block_14", ["potassium\n"]], ["block_15", ["K(s)\n0\n0\n64.7\n"]], ["block_16", ["K(g)\n89.0\n60.5\n160.3\n"]], ["block_17", ["K(aq)\n\u2013252.4\n\u2013283.3\n102.5\n"]], ["block_18", ["KF(s)\n\u2013576.27\n\u2013537.75\n66.57\n"]], ["block_19", ["KCl(s)\n\u2013436.5\n\u2013408.5\n82.6\n"]], ["block_20", ["rubidium\n"]], ["block_21", ["Rb(aq)\n\u2013246\n\u2013282.2\n124\n"]], ["block_22", ["silicon\n"]], ["block_23", ["Si(s)\n0\n0\n18.8\n"]], ["block_24", ["Si(g)\n450.0\n405.5\n168.0\n"]], ["block_25", ["SiO2(s)\n\u2013910.7\n\u2013856.3\n41.5\n"]], ["block_26", [" G \u2022 Standard Thermodynamic Properties for Selected Substances \n 1113 \n"]]], "page_1127": [["block_0", [" 1114 \n G \u2022 Standard Thermodynamic Properties for Selected Substances \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE G1 \n"]], ["block_3", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_4", ["SiH4(g)\n34.3\n56.9\n204.6\n"]], ["block_5", ["H2SiO3(s)\n\u20131188.67\n\u20131092.44\n133.89\n"]], ["block_6", ["H4SiO4(s)\n\u20131481.14\n\u20131333.02\n192.46\n"]], ["block_7", ["SiF4(g)\n\u20131615.0\n\u20131572.8\n282.8\n"]], ["block_8", ["SiCl4(l)\n\u2013687.0\n\u2013619.8\n239.7\n"]], ["block_9", ["SiCl4(g)\n\u2013662.75\n\u2013622.58\n330.62\n"]], ["block_10", ["SiC(s, beta cubic)\n\u201373.22\n\u201370.71\n16.61\n"]], ["block_11", ["SiC(s, alpha hexagonal)\n\u201371.55\n\u201369.04\n16.48\n"]], ["block_12", ["silver\n"]], ["block_13", ["Ag(s)\n0\n0\n42.55\n"]], ["block_14", ["Ag(g)\n284.9\n246.0\n172.89\n"]], ["block_15", ["Ag(aq)\n105.6\n77.11\n72.68\n"]], ["block_16", ["Ag2O(s)\n\u201331.05\n\u201311.20\n121.3\n"]], ["block_17", ["AgCl(s)\n\u2013127.0\n\u2013109.8\n96.3\n"]], ["block_18", ["Ag2S(s)\n\u201332.6\n\u201340.7\n144.0\n"]], ["block_19", ["sodium\n"]], ["block_20", ["Na(s)\n0\n0\n51.3\n"]], ["block_21", ["Na(g)\n107.5\n77.0\n153.7\n"]], ["block_22", ["Na(aq)\n\u2013240.1\n\u2013261.9\n59\n"]], ["block_23", ["Na2O(s)\n\u2013414.2\n\u2013375.5\n75.1\n"]], ["block_24", ["NaCl(s)\n\u2013411.2\n\u2013384.1\n72.1\n"]], ["block_25", ["strontium\n"]], ["block_26", ["Sr(aq)\n\u2013545.8\n\u2013557.3\n\u201332.6\n"]], ["block_27", ["sulfur\n"]]], "page_1128": [["block_0", [" TABLE G1 \n"]], ["block_1", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_2", ["S8(s) (rhombic)\n0\n0\n256.8\n"]], ["block_3", ["S(g)\n278.81\n238.25\n167.82\n"]], ["block_4", ["S(aq)\n41.8\n83.7\n22\n"]], ["block_5", ["SO2(g)\n\u2013296.83\n\u2013300.1\n248.2\n"]], ["block_6", ["SO3(g)\n\u2013395.72\n\u2013371.06\n256.76\n"]], ["block_7", ["SO4 (aq)\n\u2013909.3\n\u2013744.5\n20.1\n"]], ["block_8", ["S2O3 (aq)\n\u2013648.5\n\u2013522.5\n67\n"]], ["block_9", ["H2S(g)\n\u201320.6\n\u201333.4\n205.8\n"]], ["block_10", ["HS(aq)\n\u201317.7\n12.6\n61.1\n"]], ["block_11", ["H2SO4(l)\n\u2013813.989\n\u2013690.00\n156.90\n"]], ["block_12", ["HSO4 (aq)\n\u2013885.75\n\u2013752.87\n126.9\n"]], ["block_13", ["H2S2O7(s)\n\u20131273.6\n\u2014\n\u2014\n"]], ["block_14", ["SF4(g)\n\u2013728.43\n\u2013684.84\n291.12\n"]], ["block_15", ["SF6(g)\n\u20131220.5\n\u20131116.5\n291.5\n"]], ["block_16", ["SCl2(l)\n\u201350\n\u2014\n\u2014\n"]], ["block_17", ["SCl2(g)\n\u201319.7\n\u2014\n\u2014\n"]], ["block_18", ["S2Cl2(l)\n\u201359.4\n\u2014\n\u2014\n"]], ["block_19", ["S2Cl2(g)\n\u201319.50\n\u201329.25\n319.45\n"]], ["block_20", ["SOCl2(g)\n\u2013212.55\n\u2013198.32\n309.66\n"]], ["block_21", ["SOCl2(l)\n\u2013245.6\n\u2014\n\u2014\n"]], ["block_22", ["SO2Cl2(l)\n\u2013394.1\n\u2014\n\u2014\n"]], ["block_23", ["SO2Cl2(g)\n\u2013354.80\n\u2013310.45\n311.83\n"]], ["block_24", ["tin\n"]], ["block_25", ["Sn(s)\n0\n0\n51.2\n"]], ["block_26", [" G \u2022 Standard Thermodynamic Properties for Selected Substances \n 1115 \n"]]], "page_1129": [["block_0", [" 1116 \n G \u2022 Standard Thermodynamic Properties for Selected Substances \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE G1 \n"]], ["block_3", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_4", ["Sn(g)\n301.2\n266.2\n168.5\n"]], ["block_5", ["SnO(s)\n\u2013285.8\n\u2013256.9\n56.5\n"]], ["block_6", ["SnO2(s)\n\u2013577.6\n\u2013515.8\n49.0\n"]], ["block_7", ["SnCl4(l)\n\u2013511.3\n\u2013440.1\n258.6\n"]], ["block_8", ["SnCl4(g)\n\u2013471.5\n\u2013432.2\n365.8\n"]], ["block_9", ["titanium\n"]], ["block_10", ["Ti(s)\n0\n0\n30.7\n"]], ["block_11", ["Ti(g)\n473.0\n428.4\n180.3\n"]], ["block_12", ["TiO2(s)\n\u2013944.0\n\u2013888.8\n50.6\n"]], ["block_13", ["TiCl4(l)\n\u2013804.2\n\u2013737.2\n252.4\n"]], ["block_14", ["TiCl4(g)\n\u2013763.2\n\u2013726.3\n353.2\n"]], ["block_15", ["tungsten\n"]], ["block_16", ["W(s)\n0\n0\n32.6\n"]], ["block_17", ["W(g)\n849.4\n807.1\n174.0\n"]], ["block_18", ["WO3(s)\n\u2013842.9\n\u2013764.0\n75.9\n"]], ["block_19", ["zinc\n"]], ["block_20", ["Zn(s)\n0\n0\n41.6\n"]], ["block_21", ["Zn(g)\n130.73\n95.14\n160.98\n"]], ["block_22", ["Zn(aq)\n\u2013153.9\n\u2013147.1\n\u2013112.1\n"]], ["block_23", ["ZnO(s)\n\u2013350.5\n\u2013320.5\n43.7\n"]], ["block_24", ["ZnCl2(s)\n\u2013415.1\n\u2013369.43\n111.5\n"]], ["block_25", ["ZnS(s)\n\u2013206.0\n\u2013201.3\n57.7\n"]], ["block_26", ["ZnSO4(s)\n\u2013982.8\n\u2013871.5\n110.5\n"]], ["block_27", ["ZnCO3(s)\n\u2013812.78\n\u2013731.57\n82.42\n"]]], "page_1130": [["block_0", [" TABLE G1 \n"]], ["block_1", [" Substance \n (kJ mol \u20131 ) \n (kJ mol \u20131 ) \n (J K \u20131 mol \u20131 ) \n"]], ["block_2", ["complexes\n"]], ["block_3", ["[Co(NH3)4(NO2)2]NO3, cis\n\u2013898.7\n\u2014\n\u2014\n"]], ["block_4", ["[Co(NH3)4(NO2)2]NO3, trans\n\u2013896.2\n\u2014\n\u2014\n"]], ["block_5", ["NH4[Co(NH3)2(NO2)4]\n\u2013837.6\n\u2014\n\u2014\n"]], ["block_6", ["[Co(NH3)6][Co(NH3)2(NO2)4]3\n\u20132733.0\n\u2014\n\u2014\n"]], ["block_7", ["[Co(NH3)4Cl2]Cl, cis\n\u2013874.9\n\u2014\n\u2014\n"]], ["block_8", ["[Co(NH3)4Cl2]Cl, trans\n\u2013877.4\n\u2014\n\u2014\n"]], ["block_9", ["[Co(en)2(NO2)2]NO3, cis\n\u2013689.5\n\u2014\n\u2014\n"]], ["block_10", ["[Co(en)2Cl2]Cl, cis\n\u2013681.2\n\u2014\n\u2014\n"]], ["block_11", ["[Co(en)2Cl2]Cl, trans\n\u2013677.4\n\u2014\n\u2014\n"]], ["block_12", ["[Co(en)3](ClO4)3\n\u2013762.7\n\u2014\n\u2014\n"]], ["block_13", ["[Co(en)3]Br2\n\u2013595.8\n\u2014\n\u2014\n"]], ["block_14", ["[Co(en)3]I2\n\u2013475.3\n\u2014\n\u2014\n"]], ["block_15", ["[Co(en)3]I3\n\u2013519.2\n\u2014\n\u2014\n"]], ["block_16", ["[Co(NH3)6](ClO4)3\n\u20131034.7\n\u2013221.1\n615\n"]], ["block_17", ["[Co(NH3)5NO2](NO3)2\n\u20131088.7\n\u2013412.9\n331\n"]], ["block_18", ["[Co(NH3)6](NO3)3\n\u20131282.0\n\u2013524.5\n448\n"]], ["block_19", ["[Co(NH3)5Cl]Cl2\n\u20131017.1\n\u2013582.5\n366.1\n"]], ["block_20", ["[Pt(NH3)4]Cl2\n\u2013725.5\n\u2014\n\u2014\n"]], ["block_21", ["[Ni(NH3)6]Cl2\n\u2013994.1\n\u2014\n\u2014\n"]], ["block_22", ["[Ni(NH3)6]Br2\n\u2013923.8\n\u2014\n\u2014\n"]], ["block_23", ["[Ni(NH3)6]I2\n\u2013808.3\n\u2014\n\u2014\n"]], ["block_24", [" G \u2022 Standard Thermodynamic Properties for Selected Substances \n 1117 \n"]]], "page_1131": [["block_0", [" 1118 \n G \u2022 Standard Thermodynamic Properties for Selected Substances \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_1132": [["block_0", [" APPENDIX H \n"]], ["block_1", ["Ionization Constants of Weak Acids\n"]], ["block_2", [" TABLE H1 \n"]], ["block_3", [" Acid \n Formula \n K a at 25 \u00b0C \n Lewis Structure \n"]], ["block_4", ["acetic\nCH3CO2 H \n1.8\n10\n"]], ["block_5", ["arsenic\n"]], ["block_6", ["arsenous\n H 3 AsO3\n5.1\n10\n"]], ["block_7", ["boric\n H 3 BO3\n5.4\n10\n"]], ["block_8", ["carbonic\n"]], ["block_9", ["cyanic\n H CNO\n2\n10\n"]], ["block_10", ["formic\nHCO2 H \n1.8\n10\n"]], ["block_11", [" H 3 AsO4\n5.5\n10\n"]], ["block_12", [{"image_0": "1132_0.png", "coords": [206, 311, 249, 330]}]], ["block_13", [{"image_1": "1132_1.png", "coords": [206, 346, 249, 364]}]], ["block_14", [" H 2 CO3\n4.3\n10\n"]], ["block_15", [{"image_2": "1132_2.png", "coords": [206, 566, 241, 585]}]], ["block_16", ["Ionization Constants of Weak Acids\n"]], ["block_17", ["1.7\n10\n"]], ["block_18", ["3.0\n10\n"]], ["block_19", ["4.7\n10\n"]], ["block_20", [{"image_3": "1132_3.png", "coords": [323, 214, 399, 270]}]], ["block_21", [{"image_4": "1132_4.png", "coords": [323, 295, 387, 355]}]], ["block_22", [{"image_5": "1132_5.png", "coords": [323, 380, 384, 437]}]], ["block_23", [{"image_6": "1132_6.png", "coords": [323, 453, 387, 525]}]], ["block_24", [{"image_7": "1132_7.png", "coords": [323, 541, 379, 584]}]], ["block_25", [{"image_8": "1132_8.png", "coords": [323, 600, 387, 633]}]], ["block_26", [{"image_9": "1132_9.png", "coords": [323, 649, 375, 681]}]], ["block_27", [" H \u2022 Ionization Constants of Weak Acids \n 1119 \n"]]], "page_1133": [["block_0", [" 1120 \n H \u2022 Ionization Constants of Weak Acids \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE H1 \n"]], ["block_3", [" Acid \n Formula \n K a at 25 \u00b0C \n Lewis Structure \n"]], ["block_4", ["hydrazoic\n H N3\n2.5\n10\n"]], ["block_5", ["hydrocyanic\n H CN\n4.9\n10\n"]], ["block_6", ["hydrofluoric\n H F\n6.4\n10\n"]], ["block_7", ["hydrogen peroxide\n H 2 O2\n2.4\n10\n"]], ["block_8", ["hydrogen selenide\n"]], ["block_9", ["hydrogen sulfate ion\n"]], ["block_10", ["hydrogen sulfide\n"]], ["block_11", ["hydrogen telluride\n"]], ["block_12", ["hypobromous\n H BrO\n2.8\n10\n"]], ["block_13", ["hypochlorous\n H ClO\n2.9\n10\n"]], ["block_14", ["nitrous\n H NO2\n4.6\n10\n"]], ["block_15", ["oxalic\n"]], ["block_16", ["phosphoric\n"]], ["block_17", [" H 2 Se\n1.29\n10\n"]], ["block_18", [" H Se\n1\n10\n"]], ["block_19", [{"image_0": "1133_0.png", "coords": [206, 305, 241, 324]}]], ["block_20", [" H 2 S\n8.9\n10\n"]], ["block_21", [" H S\n1.0\n10\n"]], ["block_22", [" H 2 Te\n2.3\n10\n"]], ["block_23", [" H Te\n1.6\n10\n"]], ["block_24", [" H 2 C2O4\n6.0\n10\n"]], ["block_25", [{"image_1": "1133_1.png", "coords": [206, 584, 245, 603]}]], ["block_26", [" H 3 PO4\n7.5\n10\n"]], ["block_27", [{"image_2": "1133_2.png", "coords": [206, 644, 245, 663]}]], ["block_28", [{"image_3": "1133_3.png", "coords": [206, 678, 244, 697]}]], ["block_29", ["1.2\n10\n"]], ["block_30", ["6.1\n10\n"]], ["block_31", ["6.2\n10\n"]], ["block_32", ["4.2\n10\n"]], ["block_33", [{"image_4": "1133_4.png", "coords": [323, 90, 505, 131]}]], ["block_34", [{"image_5": "1133_5.png", "coords": [323, 198, 394, 220]}]], ["block_35", [{"image_6": "1133_6.png", "coords": [323, 286, 383, 342]}]], ["block_36", [{"image_7": "1133_7.png", "coords": [323, 511, 380, 543]}]], ["block_37", [{"image_8": "1133_8.png", "coords": [323, 562, 434, 599]}]], ["block_38", [{"image_9": "1133_9.png", "coords": [323, 621, 394, 694]}]]], "page_1134": [["block_0", [" TABLE H1 \n"]], ["block_1", [" Acid \n Formula \n K a at 25 \u00b0C \n Lewis Structure \n"]], ["block_2", ["phosphorous\n"]], ["block_3", ["sulfurous\n"]], ["block_4", [" H 3 PO3\n5\n10\n"]], ["block_5", [{"image_0": "1134_0.png", "coords": [206, 115, 244, 134]}]], ["block_6", [" H 2 SO3\n1.6\n10\n"]], ["block_7", [{"image_1": "1134_1.png", "coords": [206, 175, 241, 194]}]], ["block_8", ["2.0\n10\n"]], ["block_9", ["6.4\n10\n"]], ["block_10", [{"image_2": "1134_2.png", "coords": [323, 91, 387, 133]}]], ["block_11", [{"image_3": "1134_3.png", "coords": [323, 151, 385, 194]}]], ["block_12", [" H \u2022 Ionization Constants of Weak Acids \n 1121 \n"]]], "page_1135": [["block_0", [" 1122 \n H \u2022 Ionization Constants of Weak Acids \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_1136": [["block_0", [" APPENDIX I \n"]], ["block_1", ["Ionization Constants of Weak Bases\n"]], ["block_2", [" TABLE I1 \n"]], ["block_3", [" Base \n Lewis Structure \n K b at 25 \u00b0C \n"]], ["block_4", ["ammonia\n"]], ["block_5", ["dimethylamine\n"]], ["block_6", ["methylamine\n"]], ["block_7", ["phenylamine (aniline)\n"]], ["block_8", ["trimethylamine\n"]], ["block_9", ["Ionization Constants of Weak Bases\n"]], ["block_10", [{"image_0": "1136_0.png", "coords": [283, 214, 334, 251]}]], ["block_11", [{"image_1": "1136_1.png", "coords": [283, 267, 374, 318]}]], ["block_12", [{"image_2": "1136_2.png", "coords": [283, 334, 354, 386]}]], ["block_13", [{"image_3": "1136_3.png", "coords": [283, 402, 369, 504]}]], ["block_14", [{"image_4": "1136_4.png", "coords": [283, 519, 369, 601]}]], ["block_15", [" I \u2022 Ionization Constants of Weak Bases \n 1123 \n"]], ["block_16", ["1.8\n10\n"]], ["block_17", ["5.9\n10\n"]], ["block_18", ["4.4\n10\n"]], ["block_19", ["4.3\n10\n"]], ["block_20", ["6.3\n10\n"]]], "page_1137": [["block_0", [" 1124 \n I \u2022 Ionization Constants of Weak Bases \n"]], ["block_1", [" Access for free at openstax.org \n"]]], "page_1138": [["block_0", [" APPENDIX J \n"]], ["block_1", ["Solubility Products\n"]], ["block_2", [" TABLE J1 \n"]], ["block_3", [" Substance \n K sp at 25 \u00b0C \n"]], ["block_4", ["Al(OH)3\n2\n10\n"]], ["block_5", ["BaCO3\n1.6\n10\n"]], ["block_6", ["BaC2O4\u00b72H2O\n1.1\n10\n"]], ["block_7", ["BaSO4\n2.3\n10\n"]], ["block_8", ["BaCrO4\n8.5\n10\n"]], ["block_9", ["BaF2\n2.4\n10\n"]], ["block_10", ["Ba(OH)2\u00b78H2O\n5.0\n10\n"]], ["block_11", ["Ba3(PO4)2\n6\n10\n"]], ["block_12", ["Ba3(AsO4)2\n1.1\n10\n"]], ["block_13", ["BiO(OH)\n4\n10\n"]], ["block_14", ["BiOCl\n1.8\n10\n"]], ["block_15", ["Bi2S3\n1\n10\n"]], ["block_16", ["Cd(OH)2\n5.9\n10\n"]], ["block_17", ["CdS\n1.0\n10\n"]], ["block_18", ["CdCO3\n5.2\n10\n"]], ["block_19", ["Solubility Products\n"]], ["block_20", ["aluminum\n"]], ["block_21", ["cadmium\n"]], ["block_22", ["bismuth\n"]], ["block_23", ["barium\n"]], ["block_24", [" J \u2022 Solubility Products \n 1125 \n"]]], "page_1139": [["block_0", [" 1126 \n J \u2022 Solubility Products \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE J1 \n"]], ["block_3", [" Substance \n K sp at 25 \u00b0C \n"]], ["block_4", ["Ca(OH)2\n1.3\n10\n"]], ["block_5", ["CaCO3\n8.7\n10\n"]], ["block_6", ["CaSO4\u00b72H2O\n6.1\n10\n"]], ["block_7", ["CaC2O4\u00b7H2O\n1.96\n10\n"]], ["block_8", ["Ca3(PO4)2\n1.3\n10\n"]], ["block_9", ["CaHPO4\n7\n10\n"]], ["block_10", ["CaF2\n4.0\n10\n"]], ["block_11", ["Cr(OH)3\n6.7\n10\n"]], ["block_12", ["Co(OH)2\n2.5\n10\n"]], ["block_13", ["CoS(\u03b1)\n5\n10\n"]], ["block_14", ["CoS(\u03b2)\n3\n10\n"]], ["block_15", ["CoCO3\n1.4\n10\n"]], ["block_16", ["Co(OH)3\n2.5\n10\n"]], ["block_17", ["CuCl\n1.2\n10\n"]], ["block_18", ["CuBr\n6.27\n10\n"]], ["block_19", ["CuI\n1.27\n10\n"]], ["block_20", ["CuSCN\n1.6\n10\n"]], ["block_21", ["Cu2S\n2.5\n10\n"]], ["block_22", ["Cu(OH)2\n2.2\n10\n"]], ["block_23", ["CuS\n8.5\n10\n"]], ["block_24", ["chromium\n"]], ["block_25", ["calcium\n"]], ["block_26", ["copper\n"]], ["block_27", ["cobalt\n"]]], "page_1140": [["block_0", [" TABLE J1 \n"]], ["block_1", [" Substance \n K sp at 25 \u00b0C \n"]], ["block_2", ["CuCO3\n2.5\n10\n"]], ["block_3", ["Fe(OH)2\n1.8\n10\n"]], ["block_4", ["FeCO3\n2.1\n10\n"]], ["block_5", ["FeS\n3.7\n10\n"]], ["block_6", ["Fe(OH)3\n4\n10\n"]], ["block_7", ["Pb(OH)2\n1.2\n10\n"]], ["block_8", ["PbF2\n4\n10\n"]], ["block_9", ["PbCl2\n1.6\n10\n"]], ["block_10", ["PbBr2\n4.6\n10\n"]], ["block_11", ["PbI2\n1.4\n10\n"]], ["block_12", ["PbCO3\n1.5\n10\n"]], ["block_13", ["PbS\n7\n10\n"]], ["block_14", ["PbCrO4\n2\n10\n"]], ["block_15", ["PbSO4\n1.3\n10\n"]], ["block_16", ["Pb3(PO4)2\n1\n10\n"]], ["block_17", ["Mg(OH)2\n8.9\n10\n"]], ["block_18", ["MgCO3\u00b73H2O\nca 1\n10\n"]], ["block_19", ["MgNH4PO4\n3\n10\n"]], ["block_20", ["MgF2\n6.4\n10\n"]], ["block_21", ["MgC2O4\n7\n10\n"]], ["block_22", ["magnesium\n"]], ["block_23", ["manganese\n"]], ["block_24", ["lead\n"]], ["block_25", ["iron\n"]], ["block_26", [" J \u2022 Solubility Products \n 1127 \n"]]], "page_1141": [["block_0", [" 1128 \n J \u2022 Solubility Products \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE J1 \n"]], ["block_3", [" Substance \n K sp at 25 \u00b0C \n"]], ["block_4", ["Mn(OH)2\n2\n10\n"]], ["block_5", ["MnCO3\n8.8\n10\n"]], ["block_6", ["MnS\n2.3\n10\n"]], ["block_7", ["Hg2O\u00b7H2O\n3.6\n10\n"]], ["block_8", ["Hg2Cl2\n1.1\n10\n"]], ["block_9", ["Hg2Br2\n1.3\n10\n"]], ["block_10", ["Hg2I2\n4.5\n10\n"]], ["block_11", ["Hg2CO3\n9\n10\n"]], ["block_12", ["Hg2SO4\n7.4\n10\n"]], ["block_13", ["Hg2S\n1.0\n10\n"]], ["block_14", ["Hg2CrO4\n2\n10\n"]], ["block_15", ["HgS\n1.6\n10\n"]], ["block_16", ["Ni(OH)2\n1.6\n10\n"]], ["block_17", ["NiCO3\n1.4\n10\n"]], ["block_18", ["NiS(\u03b1)\n4\n10\n"]], ["block_19", ["NiS(\u03b2)\n1.3\n10\n"]], ["block_20", ["KClO4\n1.05\n10\n"]], ["block_21", ["K2PtCl6\n7.48\n10\n"]], ["block_22", ["KHC4H4O6\n3\n10\n"]], ["block_23", ["potassium\n"]], ["block_24", ["mercury\n"]], ["block_25", ["nickel\n"]], ["block_26", ["silver\n"]], ["block_27", ["2\n10\n"]]], "page_1142": [["block_0", [" TABLE J1 \n"]], ["block_1", [" Substance \n K sp at 25 \u00b0C \n"]], ["block_2", ["AgCl\n1.6\n10\n"]], ["block_3", ["AgBr\n5.0\n10\n"]], ["block_4", ["AgI\n1.5\n10\n"]], ["block_5", ["AgCN\n1.2\n10\n"]], ["block_6", ["AgSCN\n1.0\n10\n"]], ["block_7", ["Ag2S\n1.6\n10\n"]], ["block_8", ["Ag2CO3\n8.1\n10\n"]], ["block_9", ["Ag2CrO4\n9.0\n10\n"]], ["block_10", ["Ag4Fe(CN)6\n1.55\n10\n"]], ["block_11", ["Ag2SO4\n1.2\n10\n"]], ["block_12", ["Ag3PO4\n1.8\n10\n"]], ["block_13", ["Sr(OH)2\u00b78H2O\n3.2\n10\n"]], ["block_14", ["SrCO3\n7\n10\n"]], ["block_15", ["SrCrO4\n3.6\n10\n"]], ["block_16", ["SrSO4\n3.2\n10\n"]], ["block_17", ["SrC2O4\u00b7H2O\n4\n10\n"]], ["block_18", ["TlCl\n1.7\n10\n"]], ["block_19", ["TlSCN\n1.6\n10\n"]], ["block_20", ["Tl2S\n6\n10\n"]], ["block_21", ["Tl(OH)3\n6.3\n10\n"]], ["block_22", ["Sn(OH)2\n3\n10\n"]], ["block_23", ["strontium\n"]], ["block_24", ["thallium\n"]], ["block_25", ["tin\n"]], ["block_26", [" J \u2022 Solubility Products \n 1129 \n"]]], "page_1143": [["block_0", [" 1130 \n J \u2022 Solubility Products \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE J1 \n"]], ["block_3", [" Substance \n K sp at 25 \u00b0C \n"]], ["block_4", ["SnS\n1\n10\n"]], ["block_5", ["Sn(OH)4\n1.0\n10\n"]], ["block_6", ["ZnCO3\n2\n10\n"]], ["block_7", ["zinc\n"]]], "page_1144": [["block_0", [" APPENDIX K \n"]], ["block_1", ["Formation Constants for Complex Ions\n"]], ["block_2", [" TABLE K1 \n"]], ["block_3", [" Equilibrium \n K f \n"]], ["block_4", ["Formation Constants for Complex Ions\n"]], ["block_5", [" K \u2022 Formation Constants for Complex Ions \n 1131 \n"]], ["block_6", ["7\n10\n"]], ["block_7", ["1.3\n10\n"]], ["block_8", ["3\n10\n"]], ["block_9", ["1.3\n10\n"]], ["block_10", ["2.3\n10\n"]], ["block_11", ["1.0\n10\n"]], ["block_12", ["1.7\n10\n"]], ["block_13", ["1.5\n10\n"]], ["block_14", ["2\n10\n"]], ["block_15", ["3.2\n10\n"]], ["block_16", ["1.1\n10\n"]], ["block_17", ["2.0\n10\n"]], ["block_18", ["1.8\n10\n"]], ["block_19", ["1\n10\n"]], ["block_20", ["1.7\n10\n"]], ["block_21", ["2.1\n10\n"]], ["block_22", ["2\n10\n"]]], "page_1145": [["block_0", [" 1132 \n K \u2022 Formation Constants for Complex Ions \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE K1 \n"]], ["block_3", [" Equilibrium \n K f \n"]], ["block_4", ["8.9\n10\n"]], ["block_5", ["1.2\n10\n"]], ["block_6", ["3.0\n10\n"]], ["block_7", ["1\n10\n"]], ["block_8", ["1.0\n10\n"]], ["block_9", ["1\n10\n"]]], "page_1146": [["block_0", [" APPENDIX L \n"]], ["block_1", ["Standard Electrode (Half-Cell) Potentials\n"]], ["block_2", [" TABLE L1 \n"]], ["block_3", [" Half-Reaction \n E\u00b0 (V) \n"]], ["block_4", ["Standard Electrode (Half-Cell) Potentials\n"]], ["block_5", [" L \u2022 Standard Electrode (Half-Cell) Potentials \n 1133 \n"]], ["block_6", ["+0.7996\n"]], ["block_7", ["+0.22233\n"]], ["block_8", ["\u22120.31\n"]], ["block_9", ["+0.45\n"]], ["block_10", ["+0.373\n"]], ["block_11", ["+0.017\n"]], ["block_12", ["\u22122.07\n"]], ["block_13", ["\u22121.662\n"]], ["block_14", ["\u22122.048\n"]], ["block_15", ["+1.498\n"]], ["block_16", ["+1.692\n"]], ["block_17", ["\u22122.912\n"]], ["block_18", ["\u22121.847\n"]], ["block_19", ["+1.0873\n"]], ["block_20", ["\u22122.868\n"]], ["block_21", ["\u22122.483\n"]], ["block_22", ["+1.61\n"]], ["block_23", ["\u22120.4030\n"]], ["block_24", ["\u22121.09\n"]]], "page_1147": [["block_0", [" 1134 \n L \u2022 Standard Electrode (Half-Cell) Potentials \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE L1 \n"]], ["block_3", [" Half-Reaction \n E\u00b0 (V) \n"]], ["block_4", ["\u22120.61\n"]], ["block_5", ["\u22121.17\n"]], ["block_6", ["+1.35827\n"]], ["block_7", ["+0.36\n"]], ["block_8", ["+0.33\n"]], ["block_9", ["+0.66\n"]], ["block_10", ["+0.89\n"]], ["block_11", ["+1.189\n"]], ["block_12", ["+1.21\n"]], ["block_13", ["+1.482\n"]], ["block_14", ["+1.611\n"]], ["block_15", ["+1.628\n"]], ["block_16", ["+1.83\n"]], ["block_17", ["\u22120.28\n"]], ["block_18", ["+0.1\n"]], ["block_19", ["+0.17\n"]], ["block_20", ["\u22120.744\n"]], ["block_21", ["\u22120.407\n"]], ["block_22", ["\u22120.913\n"]], ["block_23", ["\u22120.43\n"]], ["block_24", ["\u22120.13\n"]], ["block_25", ["+1.232\n"]], ["block_26", ["\u22121.2\n"]]], "page_1148": [["block_0", [" TABLE L1 \n"]], ["block_1", [" Half-Reaction \n E\u00b0 (V) \n"]], ["block_2", [" L \u2022 Standard Electrode (Half-Cell) Potentials \n 1135 \n"]], ["block_3", ["\u22121.48\n"]], ["block_4", ["+0.153\n"]], ["block_5", ["+0.34\n"]], ["block_6", ["+0.521\n"]], ["block_7", ["+2.866\n"]], ["block_8", ["\u22120.447\n"]], ["block_9", ["+0.771\n"]], ["block_10", ["+0.36\n"]], ["block_11", ["\u22120.88\n"]], ["block_12", ["\u22121.01\n"]], ["block_13", ["\u22120.549\n"]], ["block_14", ["\u22122.279\n"]], ["block_15", ["\u22122.23\n"]], ["block_16", ["\u22120.8277\n"]], ["block_17", ["+1.776\n"]], ["block_18", ["0.00\n"]], ["block_19", ["+0.878\n"]], ["block_20", ["\u22121.55\n"]], ["block_21", ["+0.851\n"]], ["block_22", ["+0.92\n"]], ["block_23", ["+0.7973\n"]], ["block_24", ["+0.21\n"]], ["block_25", ["+0.26808\n"]]], "page_1149": [["block_0", [" 1136 \n L \u2022 Standard Electrode (Half-Cell) Potentials \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE L1 \n"]], ["block_3", [" Half-Reaction \n E\u00b0 (V) \n"]], ["block_4", ["\u22120.37\n"]], ["block_5", ["\u22120.04\n"]], ["block_6", ["\u22120.70\n"]], ["block_7", ["+0.5355\n"]], ["block_8", ["\u22120.3382\n"]], ["block_9", ["\u22122.931\n"]], ["block_10", ["\u22122.52\n"]], ["block_11", ["\u22123.04\n"]], ["block_12", ["\u22122.28\n"]], ["block_13", ["\u22122.372\n"]], ["block_14", ["\u22121.185\n"]], ["block_15", ["\u22120.05\n"]], ["block_16", ["+0.558\n"]], ["block_17", ["+1.23\n"]], ["block_18", ["+1.507\n"]], ["block_19", ["\u22122.71\n"]], ["block_20", ["\u22122.323\n"]], ["block_21", ["\u22120.257\n"]], ["block_22", ["\u22120.49\n"]], ["block_23", ["+1.593\n"]], ["block_24", ["+0.49\n"]], ["block_25", ["+0.76\n"]], ["block_26", ["+0.957\n"]], ["block_27", ["+0.92\n"]]], "page_1150": [["block_0", [" TABLE L1 \n"]], ["block_1", [" Half-Reaction \n E\u00b0 (V) \n"]], ["block_2", [" L \u2022 Standard Electrode (Half-Cell) Potentials \n 1137 \n"]], ["block_3", ["+0.10\n"]], ["block_4", ["\u22121.856\n"]], ["block_5", ["+0.401\n"]], ["block_6", ["+0.695\n"]], ["block_7", ["+1.229\n"]], ["block_8", ["\u22120.1262\n"]], ["block_9", ["+1.69\n"]], ["block_10", ["\u22120.95\n"]], ["block_11", ["\u22120.3505\n"]], ["block_12", ["+0.987\n"]], ["block_13", ["+0.591\n"]], ["block_14", ["+1.20\n"]], ["block_15", ["+0.58\n"]], ["block_16", ["+0.755\n"]], ["block_17", ["+0.68\n"]], ["block_18", ["\u22122.03\n"]], ["block_19", ["\u22122.92\n"]], ["block_20", ["\u22122.98\n"]], ["block_21", ["+0.44\n"]], ["block_22", ["\u22120.47627\n"]], ["block_23", ["+0.142\n"]], ["block_24", ["\u22122.09\n"]], ["block_25", ["\u22120.399\n"]], ["block_26", ["\u22121.2\n"]]], "page_1151": [["block_0", [" 1138 \n L \u2022 Standard Electrode (Half-Cell) Potentials \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [" TABLE L1 \n"]], ["block_3", [" Half-Reaction \n E\u00b0 (V) \n"]], ["block_4", ["\u22121.697\n"]], ["block_5", ["\u22120.86\n"]], ["block_6", ["\u22122.304\n"]], ["block_7", ["+0.151\n"]], ["block_8", ["\u22120.1375\n"]], ["block_9", ["\u22120.25\n"]], ["block_10", ["\u22120.94\n"]], ["block_11", ["\u22122.89\n"]], ["block_12", ["+0.593\n"]], ["block_13", ["\u22121.90\n"]], ["block_14", ["\u22121.630\n"]], ["block_15", ["\u22121.79\n"]], ["block_16", ["\u22121.19\n"]], ["block_17", ["\u22122.37\n"]], ["block_18", ["\u22120.7618\n"]], ["block_19", ["\u22121.26\n"]], ["block_20", ["\u22121.04\n"]], ["block_21", ["\u22121.245\n"]], ["block_22", ["\u22121.199\n"]], ["block_23", ["\u22121.40\n"]], ["block_24", ["\u22121.539\n"]]], "page_1152": [["block_0", [" APPENDIX M \n"]], ["block_1", ["Half-Lives for Several Radioactive Isotopes\n"]], ["block_2", ["1 y = years, d = days, h = hours, m = minutes, s = seconds\n2 E.C. = electron capture, S.F. = Spontaneous fission\n3 y = years, d = days, h = hours, m = minutes, s = seconds\n"]], ["block_3", [" Isotope \n Half-Life 1 \n Type of Emission 2 \n Isotope \n Half-Life 3 \n Type of Emission 4 \n"]], ["block_4", ["5730 y\n5.01 d\n"]], ["block_5", ["9.97 m\n60.55 m\n"]], ["block_6", ["4.1\n10s\n138.4 d\n"]], ["block_7", ["15.00 h\n3\n10s\n"]], ["block_8", ["14.29 d\n0.15 s\n"]], ["block_9", ["1.27\n10y\n3.05 m\n"]], ["block_10", ["0.08 s\n1.0\n10s\n"]], ["block_11", ["2.6\n10y\n1.6 s\n"]], ["block_12", ["5.27 y\n55.6 s\n"]], ["block_13", ["4.7\n10y\n3.82 d\n"]], ["block_14", ["29 y\n3.66 d\n"]], ["block_15", ["5.1\n10y\n1600 y\n"]], ["block_16", ["8.040 d\n5.75 y\n"]], ["block_17", ["5\n10y\n6.13 h\n"]], ["block_18", ["3.07 m\n1.913 y\n"]], ["block_19", ["22.3 y\n1.4\n10y\n"]], ["block_20", ["10.6 h\n22 m\n"]], ["block_21", ["26.8 m\n"]], ["block_22", ["Half-Lives for Several Radioactive Isotopes\n"]], ["block_23", [" M \u2022 Half-Lives for Several Radioactive Isotopes \n 1139 \n"]]], "page_1153": [["block_0", [" 1140 \n M \u2022 Half-Lives for Several Radioactive Isotopes \n"]], ["block_1", ["4 E.C. = electron capture, S.F. = Spontaneous fission\n"]], ["block_2", [" Access for free at openstax.org \n"]], ["block_3", [" TABLE M1 \n"]], ["block_4", [" Isotope \n Half-Life 1 \n Type of Emission 2 \n Isotope \n Half-Life 3 \n Type of Emission 4 \n"]], ["block_5", ["6.243 d\n27 d\n"]], ["block_6", ["1.59\n10y\n162.8 d\n"]], ["block_7", ["2.45\n10y\n4.5 h\n"]], ["block_8", ["7.03\n10y\n20.47 d\n"]], ["block_9", ["4.47\n10y\n3.24 h\n"]], ["block_10", ["23.54 m\n20.1 h\n"]], ["block_11", ["2.3 d\n76 m\n"]], ["block_12", ["2.407\n10y\n55 s\n"]], ["block_13", ["6.54\n10y\n0.65 s\n"]], ["block_14", ["14.4 y\n1.5 s\n"]], ["block_15", ["432.2 y\n0.8 s\n"]]], "page_1154": [["block_0", [" ANSWER KEY \n"]], ["block_1", [" Chapter 1 \n"]], ["block_2", [" 11 . The mixture can have a variety of compositions; a pure substance has a definite composition. Both have\n"]], ["block_3", [" 13 . Molecules of elements contain only one type of atom; molecules of compounds contain two or more types\n"]], ["block_4", [" 15 . Answers will vary. Sample answer: Gatorade contains water, sugar, dextrose, citric acid, salt, sodium\n"]], ["block_5", [" 17 . (a) element; (b) element; (c) compound; (d) mixture; (e) compound; (f) compound; (g) compound; (h)\n"]], ["block_6", [" 19 . In each case, a molecule consists of two or more combined atoms. They differ in that the types of atoms\n"]], ["block_7", [" 21 . Gasoline (a mixture of compounds), oxygen, and to a lesser extent, nitrogen are consumed. Carbon\n"]], ["block_8", [" 23 . (a) Increased as it would have combined with oxygen in the air thus increasing the amount of matter and\n"]], ["block_9", [" 25 . (a) 200.0 g; (b) The mass of the container and contents would decrease as carbon dioxide is a gaseous\n"]], ["block_10", [" 27 . (a) physical; (b) chemical; (c) chemical; (d) physical; (e) physical\n 29 . physical\n 31 . The value of an extensive property depends upon the amount of matter being considered, whereas the\n"]], ["block_11", [" 33 . Being extensive properties, both mass and volume are directly proportional to the amount of substance\n"]], ["block_12", [" 35 . about a yard\n 37 . (a) kilograms; (b) meters; (c) meters/second; (d) kilograms/cubic meter; (e) kelvin; (f) square meters; (g)\n"]], ["block_13", [" 39 . (a) centi-,\n10; (b) deci-,\n10; (c) Giga-,\n10; (d) kilo-,\n10; (e) milli-,\n10; (f) nano-,\n10; (g)\n"]], ["block_14", [" 41 . (a) m = 18.58 g, V = 5.7 mL. (b) d = 3.3 g/mL (c) dioptase (copper cyclosilicate, d = 3.28\u20143.31 g/mL);\n"]], ["block_15", [" 43 . (a) displaced water volume = 2.8 mL; (b) displaced water mass = 2.8 g; (c) The block mass is 2.76 g,\n"]], ["block_16", [" 45 . (a) 7.04\n10; (b) 3.344\n10; (c) 5.479\n10; (d) 2.2086\n10; (e) 1.00000\n10; (f) 6.51\n10; (g)\n"]], ["block_17", [" 47 . (a) exact; (b) exact; (c) uncertain; (d) exact; (e) uncertain; (f) uncertain\n"]], ["block_18", [" 1 . Place a glass of water outside. It will freeze if the temperature is below 0 \u00b0C.\n 3 . (a) law (states a consistently observed phenomenon, can be used for prediction); (b) theory (a widely\n"]], ["block_19", [" 5 . (a) symbolic, microscopic; (b) macroscopic; (c) symbolic, macroscopic; (d) microscopic\n 7 . Macroscopic. The heat required is determined from macroscopic properties.\n 9 . Liquids can change their shape (flow); solids can\u2019t. Gases can undergo large volume changes as pressure\n"]], ["block_20", ["accepted explanation of the behavior of matter); (c) hypothesis (a tentative explanation, can be\ninvestigated by experimentation)\n"]], ["block_21", ["changes; liquids do not. Gases flow and change volume; solids do not.\n"]], ["block_22", ["the same composition from point to point.\n"]], ["block_23", ["of atoms. They are similar in that both are comprised of two or more atoms chemically bonded together.\n"]], ["block_24", ["chloride, monopotassium phosphate, and sucrose acetate isobutyrate.\n"]], ["block_25", ["mixture\n"]], ["block_26", ["change from one substance to the next.\n"]], ["block_27", ["dioxide and water are the principal products. Carbon monoxide and nitrogen oxides are produced in\nlesser amounts.\n"]], ["block_28", ["therefore the mass. (b) 0.9 g\n"]], ["block_29", ["product and would leave the container. (c) 102.3 g\n"]], ["block_30", ["value of an intensive property is the same regardless of the amount of matter being considered.\n"]], ["block_31", ["under study. Dividing one extensive property by another will in effect \u201ccancel\u201d this dependence on\namount, yielding a ratio that is independent of amount (an intensive property).\n"]], ["block_32", ["cubic meters\n"]], ["block_33", ["pico-,\n10; (h) tera-,\n10\n"]], ["block_34", ["malachite (basic copper carbonate, d = 3.25\u20144.10 g/mL); Paraiba tourmaline (sodium lithium boron\nsilicate with copper, d = 2.82\u20143.32 g/mL)\n"]], ["block_35", ["essentially equal to the mass of displaced water (2.8 g) and consistent with Archimedes\u2019 principle of\nbuoyancy.\n"]], ["block_36", ["7.157\n10\n"]], ["block_37", [" 1141 \n"]]], "page_1155": [["block_0", [" 1142 \n"]], ["block_1", [" 49 . (a) two; (b) three; (c) five; (d) four; (e) six; (f) two; (g) five\n 51 . (a) 0.44; (b) 9.0; (c) 27; (d) 140; (e) 1.5\n10; (f) 0.44\n"]], ["block_2", [" 53 . (a) 2.15\n10; (b) 4.2\n10; (c) 2.08; (d) 0.19; (e) 27,440; (f) 43.0\n"]], ["block_3", [" 55 . (a) Archer X; (b) Archer W; (c) Archer Y\n"]], ["block_4", [" 57 . (a)\n; (b)\n; (c)\n"]], ["block_5", [" 59 .\n"]], ["block_6", [" 61 . 68\u201371 cm; 400\u2013450 g\n 63 . 355 mL\n 65 . 8\n10cm\n"]], ["block_7", [" 67 . yes; weight = 89.4 kg\n 69 . 5.0\n10mL\n"]], ["block_8", [" 71 . (a) 1.3\n10kg; (b) 2.32\n10kg; (c) 5.23\n10m; (d) 8.63\n10kg; (e) 3.76\n10m; (f) 5.4\n10\n"]], ["block_9", [" 73 . 45.4 L\n 75 . 1.0160\n10kg\n"]], ["block_10", [" 77 . (a) 394 ft; (b) 5.9634 km; (c) 6.0\n10; (d) 2.64 L; (e) 5.1\n10kg; (f) 14.5 kg; (g) 324 mg\n"]], ["block_11", [" 79 . 0.46 m; 1.5 ft/cubit\n 81 . Yes, the acid\u2019s volume is 123 mL.\n 83 . 62.6 in (about 5 ft 3 in.) and 101 lb\n 85 . (a) 3.81 cm\n8.89 cm\n2.44 m; (b) 40.6 cm\n"]], ["block_12", [" 87 . 2.70 g/cm\n"]], ["block_13", [" 89 . (a) 81.6 g; (b) 17.6 g\n 91 . (a) 5.1 mL; (b) 37 L\n 93 . 5371 \u00b0F, 3239 K\n 95 . \u221223 \u00b0C, 250 K\n 97 . \u221233.4 \u00b0C, 239.8 K\n 99 . 113 \u00b0F\n"]], ["block_14", [" Chapter 2 \n"]], ["block_15", [" 11 . (a) Cs; (b) I; (c) P; (d) Co\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", [" 1 . The starting materials consist of one green sphere and two purple spheres. The products consist of two\n"]], ["block_18", [" 3 . This statement violates Dalton\u2019s fourth postulate: In a given compound, the numbers of atoms of each type\n"]], ["block_19", [" 5 . Dalton originally thought that all atoms of a particular element had identical properties, including mass.\n"]], ["block_20", [" 7 . Both are subatomic particles that reside in an atom\u2019s nucleus. Both have approximately the same mass.\n"]], ["block_21", [" 9 . (a) The Rutherford atom has a small, positively charged nucleus, so most \u03b1 particles will pass through\n"]], ["block_22", ["green spheres and two purple spheres. This violates Dalton\u2019s postulate that that atoms are not created\nduring a chemical change, but are merely redistributed.\n"]], ["block_23", ["(and thus also the percentage) always have the same ratio.\n"]], ["block_24", ["Thus, the concept of isotopes, in which an element has different masses, was a violation of the original\nidea. To account for the existence of isotopes, the second postulate of his atomic theory was modified to\nstate that atoms of the same element must have identical chemical properties.\n"]], ["block_25", ["Protons are positively charged, whereas neutrons are uncharged.\n"]], ["block_26", ["empty space far from the nucleus and be undeflected. Those \u03b1 particles that pass near the nucleus will be\ndeflected from their paths due to positive-positive repulsion. The more directly toward the nucleus the \u03b1\nparticles are headed, the larger the deflection angle will be. (b) Higher-energy \u03b1 particles that pass near\nthe nucleus will still undergo deflection, but the faster they travel, the less the expected angle of deflection.\n(c) If the nucleus is smaller, the positive charge is smaller and the expected deflections are smaller\u2014both\nin terms of how closely the \u03b1 particles pass by the nucleus undeflected and the angle of deflection. If the\nnucleus is larger, the positive charge is larger and the expected deflections are larger\u2014more \u03b1 particles\nwill be deflected, and the deflection angles will be larger. (d) The paths followed by the \u03b1 particles match\nthe predictions from (a), (b), and (c).\n"]], ["block_27", ["Only two significant figures are justified.\n"]], ["block_28", ["m; (g) 1\n10s; (h) 2.7\n10s; (i) 1.5\n10K\n"]]], "page_1156": [["block_0", [" 13 . (a) Carbon-12, C; (b) This atom contains six protons and six neutrons. There are six electrons in a\n"]], ["block_1", [" 15 . (a) Lithium-6 contains three protons, three neutrons, and three electrons. The isotope symbol is Li or\n"]], ["block_2", [" 17 . (a) Iron, 26 protons, 24 electrons, and 32 neutrons; (b) iodine, 53 protons, 54 electrons, and 74 neutrons\n 19 . (a) 3 protons, 3 electrons, 4 neutrons; (b) 52 protons, 52 electrons, 73 neutrons; (c) 47 protons, 47\n"]], ["block_3", [" 21 . Let us use neon as an example. Since there are three isotopes, there is no way to be sure to accurately\n"]], ["block_4", [" 23 . 79.90 amu\n 25 . Turkey source: 20.3% (of 10.0129 amu isotope); US source: 19.1% (of 10.0129 amu isotope)\n 27 . The symbol for the element oxygen, O, represents both the element and one atom of oxygen. A molecule of\n"]], ["block_5", [" 29 . (a) molecular CO2, empirical CO2; (b) molecular C2H2, empirical CH; (c) molecular C2H4, empirical CH2; (d)\n"]], ["block_6", [" 31 . (a) C4H5N2O; (b) C12H22O11; (c) HO; (d) CH2O; (e) C3H4O3\n 33 . (a) CH2O; (b) C2H4O\n 35 . (a) ethanol\n"]], ["block_7", [" 37 . (a) metal, inner transition metal; (b) nonmetal, representative element; (c) metal, representative element;\n"]], ["block_8", [" 39 . (a) He; (b) Be; (c) Li; (d) O\n 41 . (a) krypton, Kr; (b) calcium, Ca; (c) fluorine, F; (d) tellurium, Te\n 43 . (a)\n; (b)\n; (c)\n; (d)\n"]], ["block_9", [" 45 . Ionic: KCl, MgCl2; Covalent: NCl3, ICl, PCl5, CCl4\n 47 . (a) covalent; (b) ionic, Ba, O; (c) ionic,\n(d) ionic, Sr,\n(e) covalent; (f) ionic,\n"]], ["block_10", [" 49 . (a) CaS; (b) (NH4)2SO4; (c) AlBr3; (d) Na2HPO4; (e) Mg3 (PO4)2\n 51 . (a) cesium chloride; (b) barium oxide; (c) potassium sulfide; (d) beryllium chloride; (e) hydrogen bromide;\n"]], ["block_11", [" 53 . (a) RbBr; (b) MgSe; (c) Na2O; (d) CaCl2; (e) HF; (f) GaP; (g) AlBr3; (h) (NH4)2SO4\n 55 . (a) ClO2; (b) N2O4; (c) K3P; (d) Ag2S; (e) AIF3\u00b73H2O; (f) SiO2\n 57 . (a) chromium(III) oxide; (b) iron(II) chloride; (c) chromium(VI) oxide; (d) titanium(IV) chloride; (e)\n"]], ["block_12", ["neutral C atom. The net charge of such a neutral atom is zero, and the mass number is 12. (c) The\npreceding answers are correct. (d) The atom will be stable since C-12 is a stable isotope of carbon. (e) The\npreceding answer is correct. Other answers for this exercise are possible if a different element of isotope\nis chosen.\n"]], ["block_13", ["(b) Lior\n"]], ["block_14", ["electrons, 62 neutrons; (d) 7 protons, 7 electrons, 8 neutrons; (e) 15 protons, 15 electrons, 16 neutrons\n"]], ["block_15", ["predict the abundances to make the total of 20.18 amu average atomic mass. Let us guess that the\nabundances are 9% Ne-22, 91% Ne-20, and only a trace of Ne-21. The average mass would be 20.18 amu.\nChecking the nature\u2019s mix of isotopes shows that the abundances are 90.48% Ne-20, 9.25% Ne-22, and\n0.27% Ne-21, so our guessed amounts have to be slightly adjusted.\n"]], ["block_16", ["oxygen, O2, contains two oxygen atoms; the subscript 2 in the formula must be used to distinguish the\ndiatomic molecule from two single oxygen atoms.\n"]], ["block_17", ["molecular H2SO4, empirical H2SO4\n"]], ["block_18", [{"image_0": "1156_0.png", "coords": [91, 376, 208, 426]}]], ["block_19", ["(b) methoxymethane, more commonly known as dimethyl ether\n"]], ["block_20", [{"image_1": "1156_1.png", "coords": [91, 441, 208, 491]}]], ["block_21", ["(c) These molecules have the same chemical composition (types and number of atoms) but different\nchemical structures. They are structural isomers.\n"]], ["block_22", ["(d) nonmetal, representative element; (e) metal, transition metal; (f) metal, inner transition metal; (g)\nmetal, transition metal; (h) nonmetal, representative element; (i) nonmetal, representative element; (j)\nmetal, representative element\n"]], ["block_23", ["Na, O\n"]], ["block_24", ["(f) aluminum fluoride\n"]], ["block_25", [" 1143 \n"]]], "page_1157": [["block_0", [" 1144 \n"]], ["block_1", [" 59 . (a) K3PO4; (b) CuSO4; (c) CaCl2; (d) TiO2; (e) NH4NO3; (f) NaHSO4\n 61 . (a) manganese(IV) oxide; (b) mercury(I) chloride; (c) iron(III) nitrate; (d) titanium(IV) chloride; (e)\n"]], ["block_2", [" Chapter 3 \n"]], ["block_3", [" 11 . The two masses have the same numerical value, but the units are different: The molecular mass is the\n"]], ["block_4", [" 13 . (a) 256.48 g/mol; (b) 72.150 g mol; (c) 378.103 g mol; (d) 58.080 g mol; (e) 180.158 g mol\n"]], ["block_5", [" 15 . (a) 197.382 g mol; (b) 257.163 g mol; (c) 194.193 g mol; (d) 60.056 g mol; (e) 306.464 g mol\n"]], ["block_6", [" 17 . (a) 0.819 g; (b) 307 g; (c) 0.23 g; (d) 1.235\n10g (1235 kg); (e) 765 g\n"]], ["block_7", [" 19 . (a) 99.41 g; (b) 2.27 g; (c) 3.5 g; (d) 222 kg; (e) 160.1 g\n 21 . (a) 9.60 g; (b) 19.2 g; (c) 28.8 g\n 23 . zirconium: 2.038\n10atoms; 30.87 g; silicon: 2.038\n10atoms; 9.504 g; oxygen: 8.151\n10atoms;\n"]], ["block_8", [" 25 . AlPO4: 1.000 mol, or 26.98 g Al; Al2Cl6: 1.994 mol, or 53.74 g Al; Al2S3: 3.00 mol, or 80.94 g Al; The Al2S3\n"]], ["block_9", [" 27 . 3.113\n10C atoms\n"]], ["block_10", [" 29 . 0.865 servings, or about 1 serving.\n 31 . 20.0 g H2O represents the least number of molecules since it has the least number of moles.\n 33 . (a) % N = 82.24%, % H = 17.76%; (b) % Na = 29.08%, % S = 40.56%, % O = 30.36%; (c) % Ca= 38.76%\n 35 . % NH3 = 38.2%\n 37 . (a) CS2; (b) CH2O\n 39 . C6H6\n 41 . Mg3Si2H3O8 (empirical formula), Mg6Si4H6O16 (molecular formula)\n 43 . C15H15N3\n 45 . We need to know the number of moles of sulfuric acid dissolved in the solution and the volume of the\n"]], ["block_11", [" 47 . (a) 0.679 M; (b) 1.00 M; (c) 0.06998 M; (d) 1.75 M; (e) 0.070 M; (f) 6.6 M\n 49 . (a) determine the number of moles of glucose in 0.500 L of solution; determine the molar mass of glucose;\n"]], ["block_12", [" 51 . (a) 37.0 mol H2SO4, 3.63\n10g H2SO4; (b) 3.8\n10mol NaCN, 1.9\n10g NaCN; (c) 73.2 mol H2CO,\n"]], ["block_13", [" 53 . (a) Determine the molar mass of KMnO4; determine the number of moles of KMnO4 in the solution; from\n"]], ["block_14", [" 55 . (a) 5.04\n10M; (b) 0.499 M; (c) 9.92 M; (d) 1.1\n10M\n"]], ["block_15", [" 57 . 0.025 M\n 59 . 0.5000 L\n 61 . 1.9 mL\n 63 . (a) 0.125 M; (b) 0.04888 M; (c) 0.206 M; (d) 0.0056 M\n 65 . 11.9 M\n 67 . 1.6 L\n 69 . (a) The dilution equation can be used, appropriately modified to accommodate mass-based concentration\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", [" 1 . (a) 12.01 amu; (b) 12.01 amu; (c) 144.12 amu; (d) 60.05 amu\n 3 . (a) 123.896 amu; (b) 18.015 amu; (c) 164.086 amu; (d) 60.052 amu; (e) 342.297 amu\n 5 . (a) 56.107 amu; (b) 54.091 amu; (c) 199.9976 amu; (d) 97.9950 amu\n 7 . Use the molecular formula to find the molar mass; to obtain the number of moles, divide the mass of\n"]], ["block_18", [" 9 . Formic acid. Its formula has twice as many oxygen atoms as the other two compounds (one each).\n"]], ["block_19", ["compound by the molar mass of the compound expressed in grams.\n"]], ["block_20", ["Therefore, 0.60 mol of formic acid would be equivalent to 1.20 mol of a compound containing a single\noxygen atom.\n"]], ["block_21", ["cobalt(II) chloride hexahydrate; (f) molybdenum(IV) sulfide\n"]], ["block_22", ["copper(II) bromide\n"]], ["block_23", ["mass of 1 molecule while the molar mass is the mass of 6.022\n10molecules.\n"]], ["block_24", ["21.66 g\n"]], ["block_25", ["sample thus contains the greatest mass of Al.\n"]], ["block_26", ["solution.\n"]], ["block_27", ["determine the mass of glucose from the number of moles and its molar mass; (b) 27 g\n"]], ["block_28", ["2.20 kg H2CO; (d) 5.9\n10mol FeSO4, 8.9\n10g FeSO4\n"]], ["block_29", ["the number of moles and the volume of solution, determine the molarity; (b) 1.15\n10M\n"]], ["block_30", ["units:\n. This equation can be rearranged to isolate mass1 and the\n"]], ["block_31", ["given quantities substituted into this equation. (b) 58.8 g\n"]]], "page_1158": [["block_0", [" 71 . 114 g\n 73 . 1.75\n10M\n"]], ["block_1", [" 75 . 95 mg/dL\n 77 . 2.38\n10mol\n"]], ["block_2", [" 79 . 0.29 mol\n"]], ["block_3", [" Chapter 4 \n"]], ["block_4", [" 11 . (a)\n"]], ["block_5", [" 13 . (a) oxidation-reduction (addition); (b) acid-base (neutralization); (c) oxidation-reduction (combustion)\n 15 . It is an oxidation-reduction reaction because the oxidation state of the silver changes during the reaction.\n 17 . (a) H +1, P +5, O \u22122; (b) Al +3, H +1, O \u22122; (c) Se +4, O \u22122; (d) K +1, N +3, O \u22122; (e) In +3, S \u22122; (f) P +3, O \u22122\n 19 . (a) acid-base; (b) oxidation-reduction: Na is oxidized, His reduced; (c) oxidation-reduction: Mg is\n"]], ["block_6", [" 21 . (a)\n(b)\n"]], ["block_7", [" 23 . (a)\n(b)\n(c)\n"]], ["block_8", [" 25 . (a)\n(b)\n"]], ["block_9", [" 27 .\n 29 .\n 31 .\n 33 . (a)\n(b)\n"]], ["block_10", [" 35 . (a) step 1:\nstep 2:\n"]], ["block_11", [" 1 . An equation is balanced when the same number of each element is represented on the reactant and\n"]], ["block_12", [" 3 . (a)\n(b)\n"]], ["block_13", [" 5 . (a)\n(b)\n(c)\n"]], ["block_14", [" 7 . (a) Ba(NO3)2, KClO3; (b)\n(c)\n"]], ["block_15", [" 9 . (a)\n(b) complete ionic equation:\n"]], ["block_16", ["product sides. Equations must be balanced to accurately reflect the law of conservation of matter.\n"]], ["block_17", ["(b)\n"]], ["block_18", ["(c)\n"]], ["block_19", ["oxidized, Cl2 is reduced; (d) acid-base; (e) oxidation-reduction: Pis oxidized, O2 is reduced; (f) acid-base\n"]], ["block_20", ["(d)\n"]], ["block_21", ["(e)\n(f)\n"]], ["block_22", ["(d)\n"]], ["block_23", ["(a solution of H2SO4); (c)\n"]], ["block_24", ["(g)\n(h)\n"]], ["block_25", ["(d)\n"]], ["block_26", ["(c)\n(d)\n"]], ["block_27", ["(b)\n"]], ["block_28", ["net ionic equation:\n"]], ["block_29", [" 1145 \n"]]], "page_1159": [["block_0", [" 1146 \n"]], ["block_1", [" 37 . (a)\n(b)\n(c)\n"]], ["block_2", [" 39 . (a)\n(b)\n"]], ["block_3", [" 41 . (a)\n(b)\n"]], ["block_4", [" 43 . (a) 0.435 mol Na, 0.217 mol Cl2, 15.4 g Cl2; (b) 0.005780 mol HgO, 2.890\n10mol O2, 9.248\n10g O2;\n"]], ["block_5", [" 45 . (a) 0.0686 mol Mg, 1.67 g Mg; (b) 2.701\n10mol O2, 0.08644 g O2; (c) 6.43 mol MgCO3, 542 g MgCO3 (d)\n"]], ["block_6", [" 47 . (a)\n(b) 1.25 mol GaCl3, 2.2\n10g GaCl3\n"]], ["block_7", [" 49 . (a) 5.337\n10molecules; (b) 10.41 g Zn(CN)2\n"]], ["block_8", [" 51 .\n4.50 kg SiO2\n"]], ["block_9", [" 53 . 5.00\n10kg\n"]], ["block_10", [" 55 . 1.28\n10g CO2\n"]], ["block_11", [" 57 . 161.4 mL KI solution\n 59 . 176 g TiO2\n 61 . The limiting reactant is Cl2.\n 63 .\n 65 .\n 67 .\n 69 . Convert mass of ethanol to moles of ethanol; relate the moles of ethanol to the moles of ether produced\n"]], ["block_12", [" 71 . The conversion needed is\nThen compare the amount of Cr to the amount of acid\n"]], ["block_13", [" 73 . Na2C2O4 is the limiting reactant. percent yield = 86.56%\n 75 . Only four molecules can be made.\n 77 . This amount cannot be weighted by ordinary balances and is worthless.\n 79 . 3.4\n10M H2SO4\n"]], ["block_14", [" 81 . 9.6\n10M Cl\n"]], ["block_15", [" 83 . 22.4%\n 85 . The empirical formula is BH3. The molecular formula is B2H6.\n 87 . 49.6 mL\n 89 . 13.64 mL\n 91 . 0.0122 M\n 93 . 34.99 mL KOH\n 95 . The empirical formula is WCl4.\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["(c) 8.00 mol NaNO3, 6.8\n10g NaNO3; (d) 1665 mol CO2, 73.3 kg CO2; (e) 18.86 mol CuO, 2.330 kg CuCO3;\n"]], ["block_18", ["(f) 0.4580 mol C2H4Br2, 86.05 g C2H4Br2\n"]], ["block_19", ["768 mol H2O, 13.8 kg H2O; (e) 16.31 mol BaO2, 2762 g BaO2; (f) 0.207 mol C2H4, 5.81 g C2H4\n"]], ["block_20", ["using the stoichiometry of the balanced equation. Convert moles of ether to grams; divide the actual\ngrams of ether (determined through the density) by the theoretical mass to determine the percent yield;\n87.6%\n"]], ["block_21", ["present. Cr is the limiting reactant.\n"]], ["block_22", ["(c)\nand\n"]], ["block_23", ["(d)\n(e)\n"]], ["block_24", ["(e)\n"]], ["block_25", ["(f)\n(g)\n"]], ["block_26", ["(h)\n"]], ["block_27", ["(c)\n"]], ["block_28", ["(c)\n"]], ["block_29", ["(d)\n"]]], "page_1160": [["block_0", [" Chapter 5 \n"]], ["block_1", [" 7 . 1310 J; 313 cal\n 9 . 7.15 \u00b0C\n 11 . (a) 0.390 J/g \u00b0C; (b) Copper is a likely candidate.\n 13 . We assume that the density of water is 1.0 g/cm(1 g/mL) and that it takes as much energy to keep the\n"]], ["block_2", [" 15 . lesser; more heat would be lost to the coffee cup and the environment and so \u0394T for the water would be\n"]], ["block_3", [" 17 . greater, since taking the calorimeter\u2019s heat capacity into account will compensate for the thermal energy\n"]], ["block_4", [" 19 . The temperature of the coffee will drop 1 degree.\n 21 . 5.7\n10kJ\n"]], ["block_5", [" 23 . 38.5 \u00b0C\n 25 . \u22122.2 kJ; The heat produced shows that the reaction is exothermic.\n 27 . 1.4 kJ\n 29 . 22.6. Since the mass and the heat capacity of the solution is approximately equal to that of the water, the\n"]], ["block_6", [" 31 . 11.7 kJ\n 33 . 30%\n 35 . 0.24 g\n 37 . 1.4\n10Calories\n"]], ["block_7", [" 39 . The enthalpy change of the indicated reaction is for exactly 1 mol HCL and 1 mol NaOH; the heat in the\n"]], ["block_8", [" 41 . 25 kJ mol\n"]], ["block_9", [" 43 . 81 kJ mol\n"]], ["block_10", [" 45 . 5204.4 kJ\n 47 . 1.83\n10mol\n"]], ["block_11", [" 49 . \u2013802 kJ mol\n"]], ["block_12", [" 51 . 15.5 kJ/\u00baC\n 53 . 7.43 g\n 55 . Yes.\n 57 . 459.6 kJ\n 59 . \u2212494 kJ/mol\n 61 . 44.01 kJ/mol\n 63 . \u2212394 kJ\n 65 . 265 kJ\n 67 . 90.3 kJ/mol\n 69 . (a) \u22121615.0 kJ mol; (b) \u2212484.3 kJ mol; (c) 164.2 kJ; (d) \u2212232.1 kJ\n 71 . \u221254.04 kJ mol\n"]], ["block_13", [" 73 . \u22122660 kJ mol\n"]], ["block_14", [" 1 . The temperature of 1 gram of burning wood is approximately the same for both a match and a bonfire.\n"]], ["block_15", [" 3 . Heat capacity refers to the heat required to raise the temperature of the mass of the substance 1 degree;\n"]], ["block_16", [" 5 . (a) 47.6 J/\u00b0C; 11.38 cal \u00b0C; (b) 407 J/\u00b0C; 97.3 cal \u00b0C\n"]], ["block_17", ["This is an intensive property and depends on the material (wood). However, the overall amount of\nproduced heat depends on the amount of material; this is an extensive property. The amount of wood in a\nbonfire is much greater than that in a match; the total amount of produced heat is also much greater,\nwhich is why we can sit around a bonfire to stay warm, but a match would not provide enough heat to keep\nus from getting cold.\n"]], ["block_18", ["specific heat refers to the heat required to raise the temperature of 1 gram of the substance 1 degree. Thus,\nheat capacity is an extensive property, and specific heat is an intensive one.\n"]], ["block_19", ["water at 85 \u00b0F as to heat it from 72 \u00b0F to 85 \u00b0F. We also assume that only the water is going to be heated.\nEnergy required = 7.47 kWh\n"]], ["block_20", ["lesser and the calculated q would be lesser\n"]], ["block_21", ["transferred to the solution from the calorimeter; this approach includes the calorimeter itself, along with\nthe solution, as \u201csurroundings\u201d: qrxn = \u2212(qsolution + qcalorimeter); since both qsolution and qcalorimeter are\nnegative, including the latter term (qrxn) will yield a greater value for the heat of the dissolution\n"]], ["block_22", ["two-fold increase in the amount of water leads to a two-fold decrease of the temperature change.\n"]], ["block_23", ["example is produced by 0.0500 mol HCl and 0.0500 mol NaOH.\n"]], ["block_24", [" 1147 \n"]]], "page_1161": [["block_0", [" 1148 \n"]], ["block_1", [" 75 . \u201366.4 kJ\n 77 . \u2212122.8 kJ\n 79 . 3.7 kg\n 81 . On the assumption that the best rocket fuel is the one that gives off the most heat, B2H6 is the prime\n"]], ["block_2", [" 83 . \u221288.2 kJ\n 85 . (a)\n(b) 1570 L air; (c) \u2212104.5 kJ mol; (d) 75.4 \u00b0C\n"]], ["block_3", [" Chapter 6 \n"]], ["block_4", [" 11 . E = 9.502\n10J; \u03bd = 1.434\n10s\n"]], ["block_5", [" 13 . Red: 660 nm; 4.54\n10Hz; 3.01\n10J. Green: 520 nm; 5.77\n10Hz; 3.82\n10J. Blue: 440 nm;\n"]], ["block_6", [" 15 . 5.49\n10s; no\n"]], ["block_7", [" 17 . Quantized energy means that the electrons can possess only certain discrete energy values; values\n"]], ["block_8", [" 19 .\n 21 . \u22128.716\n10J\n"]], ["block_9", [" 23 . \u22123.405\n10J\n"]], ["block_10", [" 25 . 33.9 \u00c5\n 27 . 1.471\n10J\n"]], ["block_11", [" 29 . Both involve a relatively heavy nucleus with electrons moving around it, although strictly speaking, the\n"]], ["block_12", [" 31 . Both models have a central positively charged nucleus with electrons moving about the nucleus in\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", [" 1 . The spectrum consists of colored lines, at least one of which (probably the brightest) is red.\n 3 . 3.15 m\n 5 . 3.233\n10J; 2.018 eV\n"]], ["block_15", [" 7 . \u03bd = 4.568\n10s; \u03bb = 656.3 nm; Energy mol= 1.823\n10J mol; red\n"]], ["block_16", [" 9 . (a) \u03bb = 8.69\n10m; E = 2.29\n10J; (b) \u03bb = 4.59\n10m; E = 4.33\n10J; The color of (a) is red; (b)\n"]], ["block_17", ["is blue.\n"]], ["block_18", ["candidate.\n"]], ["block_19", ["6.81\n10Hz; 4.51\n10J. Somewhat different numbers are also possible.\n"]], ["block_20", ["between those quantized values are not permitted.\n"]], ["block_21", ["Bohr model works only for one-electron atoms or ions. According to classical mechanics, the Rutherford\nmodel predicts a miniature \u201csolar system\u201d with electrons moving about the nucleus in circular or elliptical\norbits that are confined to planes. If the requirements of classical electromagnetic theory that electrons in\nsuch orbits would emit electromagnetic radiation are ignored, such atoms would be stable, having\nconstant energy and angular momentum, but would not emit any visible light (contrary to observation). If\nclassical electromagnetic theory is applied, then the Rutherford atom would emit electromagnetic\nradiation of continually increasing frequency (contrary to the observed discrete spectra), thereby losing\nenergy until the atom collapsed in an absurdly short time (contrary to the observed long-term stability of\natoms). The Bohr model retains the classical mechanics view of circular orbits confined to planes having\nconstant energy and angular momentum, but restricts these to quantized values dependent on a single\nquantum number, n. The orbiting electron in Bohr\u2019s model is assumed not to emit any electromagnetic\nradiation while moving about the nucleus in its stationary orbits, but the atom can emit or absorb\nelectromagnetic radiation when the electron changes from one orbit to another. Because of the quantized\norbits, such \u201cquantum jumps\u201d will produce discrete spectra, in agreement with observations.\n"]], ["block_22", ["accordance with the Coulomb electrostatic potential. The Bohr model assumes that the electrons move in\ncircular orbits that have quantized energies, angular momentum, and radii that are specified by a single\nquantum number, n = 1, 2, 3, \u2026, but this quantization is an ad hoc assumption made by Bohr to\nincorporate quantization into an essentially classical mechanics description of the atom. Bohr also\nassumed that electrons orbiting the nucleus normally do not emit or absorb electromagnetic radiation,\nbut do so when the electron switches to a different orbit. In the quantum mechanical model, the electrons\ndo not move in precise orbits (such orbits violate the Heisenberg uncertainty principle) and, instead, a\nprobabilistic interpretation of the electron\u2019s position at any given instant is used, with a mathematical\nfunction \u03c8 called a wavefunction that can be used to determine the electron\u2019s spatial probability\ndistribution. These wavefunctions, or orbitals, are three-dimensional stationary waves that can be\nspecified by three quantum numbers that arise naturally from their underlying mathematics (no ad hoc\n"]]], "page_1162": [["block_0", [" 33 . n determines the general range for the value of energy and the probable distances that the electron can be\n"]], ["block_1", [" 35 . (a) 2p; (b) 4d; (c) 6s\n 37 . (a) 3d; (b) 1s; (c) 4f\n 39 .\n"]], ["block_2", [" 41 . (a) x. 2, y. 2, z. 2; (b) x. 1, y. 3, z. 0; (c) x. 4 0 0\ny. 2 1 0\nz. 3 2 0\n(d) x. 1, y. 2, z. 3; (e) x. l = 0, ml = 0, y.\n"]], ["block_3", [" 43 . 12\n 45 .\n"]], ["block_4", [" 47 . For example, Na: 1s2s2p; Ca: 1s2s2p3s3p; Sn: 1s2s2p3s3p3d4s4p4d5s; F:\n"]], ["block_5", [" 49 . (a) 1s2s2p; (b) 1s2s2p3s3p; (c) 1s2s2p3s3p4s3d; (d)\n"]], ["block_6", [" 51 . The charge on the ion.\n 53 . (a)\n"]], ["block_7", ["l = 1, ml = \u20131, 0, or +1, z. l = 2, ml = \u20132, \u20131, 0, +1, +2\n"]], ["block_8", ["assumptions required): the principal quantum number, n (the same one used by Bohr), which specifies\nshells such that orbitals having the same n all have the same energy and approximately the same spatial\nextent; the angular momentum quantum number l, which is a measure of the orbital\u2019s angular\nmomentum and corresponds to the orbitals\u2019 general shapes, as well as specifying subshells such that\norbitals having the same l (and n) all have the same energy; and the orientation quantum number m,\nwhich is a measure of the z component of the angular momentum and corresponds to the orientations of\nthe orbitals. The Bohr model gives the same expression for the energy as the quantum mechanical\nexpression and, hence, both properly account for hydrogen\u2019s discrete spectrum (an example of getting the\nright answers for the wrong reasons, something that many chemistry students can sympathize with), but\ngives the wrong expression for the angular momentum (Bohr orbits necessarily all have non-zero angular\nmomentum, but some quantum orbitals [s orbitals] can have zero angular momentum).\n"]], ["block_9", ["from the nucleus. l determines the shape of the orbital. m1 determines the orientation of the orbitals of the\nsame l value with respect to one another. ms determines the spin of an electron.\n"]], ["block_10", [{"image_0": "1162_0.png", "coords": [91, 265, 325, 368]}]], ["block_11", ["1s2s2p; O: 1s2s2p; Cl: 1s2s2p3s3p.\n"]], ["block_12", ["1s2s2p3s3p4s3d4p5s4d5p; (e) 1s2s2p3s3p4s3d4p5s4d5p6s4f\n"]], ["block_13", [" n \n l \nm l \n s \n"]], ["block_14", ["4\n0\n0\n"]], ["block_15", ["4\n0\n0\n"]], ["block_16", ["4\n1\n\u22121\n"]], ["block_17", ["4\n1\n0\n"]], ["block_18", ["4\n1\n+1\n"]], ["block_19", ["4\n1\n\u22121\n"]], ["block_20", [" 1149 \n"]]], "page_1163": [["block_0", [" 1150 \n"]], ["block_1", [" 55 . Zr\n 57 . Rb, Se\n"]], ["block_2", [" 59 . Although both (b) and (c) are correct, (e) encompasses both and is the best answer.\n 61 . K\n 63 . 1s2s2p3s3p4s3d4p5s4d5p6s4f5d\n"]], ["block_3", [" 65 . Co has 27 protons, 27 electrons, and 33 neutrons: 1s2s2p3s3p4s3d. I has 53 protons, 53 electrons,\n"]], ["block_4", [" 67 . Cl\n 69 . O\n 71 . Rb < Li < N < F\n 73 . 15 (5A)\n 75 . Mg < Ca < Rb < Cs\n 77 . Si< Al< Ca< K\n"]], ["block_5", [" 79 . Se, As\n"]], ["block_6", [" 81 . Mg< K< Br< As\n"]], ["block_7", [" 83 . O, IE1\n 85 . Ra\n"]], ["block_8", [" Chapter 7 \n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", [" 1 . The protons in the nucleus do not change during normal chemical reactions. Only the outer electrons\n"]], ["block_11", [" 3 . P, I, Cl, and O would form anions because they are nonmetals. Mg, In, Cs, Pb, and Co would form cations\n"]], ["block_12", [" 5 . (a) P; (b) Mg; (c) Al; (d) O; (e) Cl; (f) Cs\n"]], ["block_13", [" 7 . (a) [Ar]4s3d4p; (b) [Kr]4d5s5p(c) 1s(d) [Kr]4d; (e) [He]2s2p; (f) [Ar]3d; (g) 1s(h) [He]2s2p\n"]], ["block_14", ["move. Positive charges form when electrons are lost.\n"]], ["block_15", ["because they are metals.\n"]], ["block_16", ["(i) [Kr]4d5s(j) [Ar]3d(k) [Ar]3d, (l) [Ar]3d4s\n"]], ["block_17", [{"image_0": "1163_0.png", "coords": [91, 57, 325, 102]}]], ["block_18", ["(b)\n"]], ["block_19", [{"image_1": "1163_1.png", "coords": [91, 131, 325, 174]}]], ["block_20", ["(c)\n"]], ["block_21", [{"image_2": "1163_2.png", "coords": [91, 202, 325, 244]}]], ["block_22", ["(d)\n"]], ["block_23", [{"image_3": "1163_3.png", "coords": [91, 272, 325, 315]}]], ["block_24", ["(e)\n"]], ["block_25", [{"image_4": "1163_4.png", "coords": [91, 343, 325, 385]}]], ["block_26", ["and 78 neutrons: 1s2s2p3s3p3d4s4p4d5s5p.\n"]]], "page_1164": [["block_0", [" 11 . NaCl consists of discrete ions arranged in a crystal lattice, not covalently bonded molecules.\n 13 . ionic: (b), (d), (e), (g), and (i); covalent: (a), (c), (f), (h), (j), and (k)\n 15 . (a) Cl; (b) O; (c) O; (d) S; (e) N; (f) P; (g) N\n 17 . (a) H, C, N, O, F; (b) H, I, Br, Cl, F; (c) H, P, S, O, F; (d) Na, Al, H, P, O; (e) Ba, H, As, N, O\n 19 . N, O, F, and Cl\n 21 . (a) HF; (b) CO; (c) OH; (d) PCl; (e) NH; (f) PO; (g) CN\n 23 . (a) eight electrons:\n"]], ["block_1", [" 25 . (a)\n"]], ["block_2", [" 27 .\n"]], ["block_3", [" 29 . (a)\n"]], ["block_4", [" 9 . (a) 1s2s2p3s3p; Al: 1s2s2p; (b) 1s2s2p3s3p3d4s4p; 1s2s2p3s3p3d4s4p; (c)\n"]], ["block_5", ["1s2s2p3s3p3d4s4p5s; Sr: 1s2s2p3s3p3d4s4p; (d) 1s2s; Li: 1s; (e)\n1s2s2p3s3p3d4s4p; 1s2s2p3s3p3d4s4p; (f) 1s2s2p3s3p; 1s2s2p3s3p\n"]], ["block_6", [{"image_0": "1164_0.png", "coords": [91, 183, 208, 205]}]], ["block_7", ["(b) eight electrons:\n"]], ["block_8", [{"image_1": "1164_1.png", "coords": [91, 233, 208, 255]}]], ["block_9", ["(c) no electrons Be\n"]], ["block_10", ["(d) eight electrons:\n"]], ["block_11", [{"image_2": "1164_2.png", "coords": [91, 296, 208, 318]}]], ["block_12", ["(e) no electrons Ga\n"]], ["block_13", ["(f) no electrons Li\n"]], ["block_14", ["(g) eight electrons:\n"]], ["block_15", [{"image_3": "1164_3.png", "coords": [91, 371, 208, 393]}]], ["block_16", [{"image_4": "1164_4.png", "coords": [91, 409, 208, 431]}]], ["block_17", ["(b)\n"]], ["block_18", [{"image_5": "1164_5.png", "coords": [91, 459, 208, 481]}]], ["block_19", ["(c)\n"]], ["block_20", [{"image_6": "1164_6.png", "coords": [91, 509, 208, 531]}]], ["block_21", ["(d)\n"]], ["block_22", [{"image_7": "1164_7.png", "coords": [91, 559, 208, 581]}]], ["block_23", ["(e)\n"]], ["block_24", [{"image_8": "1164_8.png", "coords": [91, 609, 208, 631]}]], ["block_25", ["(f)\n"]], ["block_26", [{"image_9": "1164_9.png", "coords": [91, 659, 208, 681]}]], ["block_27", [{"image_10": "1164_10.png", "coords": [91, 697, 208, 710]}]], ["block_28", [" 1151 \n"]]], "page_1165": [["block_0", [" 1152 \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [{"image_0": "1165_0.png", "coords": [91, 57, 133, 74]}]], ["block_3", ["In this case, the Lewis structure is inadequate to depict the fact that experimental studies have shown two\nunpaired electrons in each oxygen molecule.\n(b)\n"]], ["block_4", [{"image_1": "1165_1.png", "coords": [91, 127, 143, 164]}]], ["block_5", ["(c)\n"]], ["block_6", [{"image_2": "1165_2.png", "coords": [91, 193, 145, 228]}]], ["block_7", ["(d)\n"]], ["block_8", [{"image_3": "1165_3.png", "coords": [91, 256, 208, 276]}]], ["block_9", ["(e)\n"]], ["block_10", [{"image_4": "1165_4.png", "coords": [91, 305, 154, 367]}]], ["block_11", ["(f)\n"]], ["block_12", [{"image_5": "1165_5.png", "coords": [91, 395, 208, 440]}]], ["block_13", ["(g)\n"]], ["block_14", [{"image_6": "1165_6.png", "coords": [91, 468, 208, 527]}]], ["block_15", ["(h)\n"]], ["block_16", [{"image_7": "1165_7.png", "coords": [91, 555, 208, 615]}]], ["block_17", ["(i)\n"]], ["block_18", [{"image_8": "1165_8.png", "coords": [91, 643, 162, 656]}]], ["block_19", ["(j)\n"]], ["block_20", [{"image_9": "1165_9.png", "coords": [91, 684, 153, 706]}]]], "page_1166": [["block_0", [" 31 . (a) SeF6:\n"]], ["block_1", [" 33 . Two valence electrons per Pb atom are transferred to Cl atoms; the resulting Pbion has a 6svalence\n"]], ["block_2", [" 35 .\n"]], ["block_3", [" 37 .\n"]], ["block_4", [" 39 . (a)\n"]], ["block_5", ["(k)\n"]], ["block_6", [{"image_0": "1166_0.png", "coords": [91, 70, 130, 86]}]], ["block_7", [{"image_1": "1166_1.png", "coords": [91, 101, 208, 160]}]], ["block_8", ["(b) XeF4:\n"]], ["block_9", [{"image_2": "1166_2.png", "coords": [91, 188, 151, 250]}]], ["block_10", ["(c)\n"]], ["block_11", [{"image_3": "1166_3.png", "coords": [91, 278, 208, 323]}]], ["block_12", ["(d) Cl2BBCl2:\n"]], ["block_13", [{"image_4": "1166_4.png", "coords": [91, 351, 162, 404]}]], ["block_14", ["shell configuration. Two of the valence electrons in the HCl molecule are shared, and the other six are\nlocated on the Cl atom as lone pairs of electrons.\n"]], ["block_15", [{"image_5": "1166_5.png", "coords": [91, 451, 559, 578]}]], ["block_16", [{"image_6": "1166_6.png", "coords": [91, 587, 217, 649]}]], ["block_17", [" 1153 \n"]]], "page_1167": [["block_0", [" 1154 \n"]], ["block_1", [" 41 .\n"]], ["block_2", [" 43 . Each bond includes a sharing of electrons between atoms. Two electrons are shared in a single bond; four\n"]], ["block_3", [" 45 . (a)\n"]], ["block_4", [" Access for free at openstax.org \n"]], ["block_5", [{"image_0": "1167_0.png", "coords": [91, 57, 202, 150]}]], ["block_6", ["(b)\n"]], ["block_7", [{"image_1": "1167_1.png", "coords": [91, 178, 182, 220]}]], ["block_8", ["(c)\n"]], ["block_9", [{"image_2": "1167_2.png", "coords": [91, 248, 197, 302]}]], ["block_10", ["(d)\n"]], ["block_11", [{"image_3": "1167_3.png", "coords": [91, 330, 177, 427]}]], ["block_12", ["(e)\n"]], ["block_13", [{"image_4": "1167_4.png", "coords": [91, 455, 182, 497]}]], ["block_14", [{"image_5": "1167_5.png", "coords": [91, 506, 208, 558]}]], ["block_15", ["electrons are shared in a double bond; and six electrons are shared in a triple bond.\n"]], ["block_16", [{"image_6": "1167_6.png", "coords": [91, 599, 262, 622]}]], ["block_17", ["(b)\n"]], ["block_18", [{"image_7": "1167_7.png", "coords": [91, 650, 442, 705]}]], ["block_19", ["(c)\n"]]], "page_1168": [["block_0", [" 47 .\n"]], ["block_1", [" 49 . (a)\n"]], ["block_2", [" 51 . (a) H: 0, Cl: 0; (b) C: 0, F: 0; (c) P: 0, Cl 0; (d) P: 0, F: 0\n 53 . Cl in Cl2: 0; Cl in BeCl2: 0; Cl in ClF5: 0\n 55 . (a)\n"]], ["block_3", [{"image_0": "1168_0.png", "coords": [91, 57, 325, 112]}]], ["block_4", ["(d)\n"]], ["block_5", [{"image_1": "1168_1.png", "coords": [91, 140, 303, 217]}]], ["block_6", ["(e)\n"]], ["block_7", [{"image_2": "1168_2.png", "coords": [91, 245, 366, 282]}]], ["block_8", [{"image_3": "1168_3.png", "coords": [91, 298, 442, 337]}]], ["block_9", [{"image_4": "1168_4.png", "coords": [91, 352, 208, 374]}]], ["block_10", ["(b)\n"]], ["block_11", [{"image_5": "1168_5.png", "coords": [91, 402, 208, 413]}]], ["block_12", ["CO has the strongest carbon-oxygen bond because there is a triple bond joining C and O. CO2 has double\nbonds.\n"]], ["block_13", [{"image_6": "1168_6.png", "coords": [91, 492, 442, 528]}]], ["block_14", ["(b)\n"]], ["block_15", [{"image_7": "1168_7.png", "coords": [91, 556, 442, 591]}]], ["block_16", ["(c)\n"]], ["block_17", [{"image_8": "1168_8.png", "coords": [91, 619, 442, 672]}]], ["block_18", ["(d)\n"]], ["block_19", [" 1155 \n"]]], "page_1169": [["block_0", [" 1156 \n"]], ["block_1", [" 57 . HOCl\n 59 . The structure that gives zero formal charges is consistent with the actual structure:\n"]], ["block_2", [" 61 . NF3;\n"]], ["block_3", [" 63 .\n"]], ["block_4", [" 65 . (a) \u2212114 kJ; (b) 30 kJ; (c) \u22121055 kJ\n 67 . The greater bond energy is in the figure on the left. It is the more stable form.\n 69 .\n"]], ["block_5", [" 71 . The S\u2013F bond in SF4 is stronger.\n 73 .\n"]], ["block_6", [" 75 . (a) When two electrons are removed from the valence shell, the Ca radius loses the outermost energy level\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [{"image_0": "1169_0.png", "coords": [91, 57, 451, 131]}]], ["block_9", [{"image_1": "1169_1.png", "coords": [91, 159, 154, 207]}]], ["block_10", [{"image_2": "1169_2.png", "coords": [91, 223, 132, 285]}]], ["block_11", [{"image_3": "1169_3.png", "coords": [91, 301, 167, 362]}]], ["block_12", [{"image_4": "1169_4.png", "coords": [91, 579, 243, 632]}]], ["block_13", ["The C\u2013C single bonds are longest.\n"]], ["block_14", ["and reverts to the lower n = 3 level, which is much smaller in radius. (b) The +2 charge on calcium pulls\nthe oxygen much closer compared with K, thereby increasing the lattice energy relative to a less charged\nion. (c) Removal of the 4s electron in Ca requires more energy than removal of the 4s electron in K because\nof the stronger attraction of the nucleus and the extra energy required to break the pairing of the\n"]]], "page_1170": [["block_0", [" 77 . (d)\n 79 . 4008 kJ/mol; both ions in MgO have twice the charge of the ions in LiF; the bond length is very similar and\n"]], ["block_1", [" 81 . (a) Na2O; Nahas a smaller radius than K; (b) BaS; Ba has a larger charge than K; (c) BaS; Ba and S have\n"]], ["block_2", [" 83 . (e)\n 85 . The placement of the two sets of unpaired electrons in water forces the bonds to assume a tetrahedral\n"]], ["block_3", [" 87 . Space must be provided for each pair of electrons whether they are in a bond or are present as lone pairs.\n"]], ["block_4", [" 89 . As long as the polar bonds are compensated (for example. two identical atoms are found directly across\n"]], ["block_5", [" 91 . (a) Both the electron geometry and the molecular structure are octahedral. (b) Both the electron geometry\n"]], ["block_6", [" 93 . (a) electron-pair geometry: octahedral, molecular structure: square pyramidal; (b) electron-pair\n"]], ["block_7", [" 95 . (a) electron-pair geometry: trigonal planar, molecular structure: bent (120\u00b0); (b) electron-pair geometry:\n"]], ["block_8", [" 97 . All of these molecules and ions contain polar bonds. Only ClF5,\nPCl3, SeF4, and\nhave dipole\n"]], ["block_9", [" 99 . SeS2, CCl2F2, PCl3, and ClNO all have dipole moments.\n 101 . P\n 103 . nonpolar\n 105 . (a) tetrahedral; (b) trigonal pyramidal; (c) bent (109\u00b0); (d) trigonal planar; (e) bent (109\u00b0); (f) bent (109\u00b0);\n"]], ["block_10", [" 107 .\n"]], ["block_11", [" 109 . (a)\n"]], ["block_12", ["electrons. The second ionization energy for K requires that an electron be removed from a lower energy\nlevel, where the attraction is much stronger from the nucleus for the electron. In addition, energy is\nrequired to unpair two electrons in a full orbital. For Ca, the second ionization potential requires removing\nonly a lone electron in the exposed outer energy level. (d) In Al, the removed electron is relatively\nunprotected and unpaired in a p orbital. The higher energy for Mg mainly reflects the unpairing of the 2s\nelectron.\n"]], ["block_13", ["both have the same structure; a quadrupling of the energy is expected based on the equation for lattice\nenergy\n"]], ["block_14", ["larger charges; (d) BaS; S has a larger charge\n"]], ["block_15", ["arrangement, and the resulting HOH molecule is bent. The HBeH molecule (in which Be has only two\nelectrons to bond with the two electrons from the hydrogens) must have the electron pairs as far from one\nanother as possible and is therefore linear.\n"]], ["block_16", ["Electron-pair geometry considers the placement of all electrons. Molecular structure considers only the\nbonding-pair geometry.\n"]], ["block_17", ["the central atom from one another), the molecule can be nonpolar.\n"]], ["block_18", ["and the molecular structure are trigonal bipyramid. (c) Both the electron geometry and the molecular\nstructure are linear. (d) Both the electron geometry and the molecular structure are trigonal planar.\n"]], ["block_19", ["geometry: tetrahedral, molecular structure: bent; (c) electron-pair geometry: octahedral, molecular\nstructure: square planar; (d) electron-pair geometry: tetrahedral, molecular structure: trigonal pyramidal;\n(e) electron-pair geometry: trigonal bypyramidal, molecular structure: seesaw; (f) electron-pair geometry:\ntetrahedral, molecular structure: bent (109\u00b0)\n"]], ["block_20", ["linear, molecular structure: linear; (c) electron-pair geometry: trigonal planar, molecular structure:\ntrigonal planar; (d) electron-pair geometry: tetrahedral, molecular structure: trigonal pyramidal; (e)\nelectron-pair geometry: tetrahedral, molecular structure: tetrahedral; (f) electron-pair geometry: trigonal\nbipyramidal, molecular structure: seesaw; (g) electron-pair geometry: tetrahedral, molecular structure:\ntrigonal pyramidal\n"]], ["block_21", ["moments.\n"]], ["block_22", ["(g) CH3CCH tetrahedral, CH3CCH linear; (h) tetrahedral; (i) H2CCCH2 linear; H2CCCH2 trigonal planar\n"]], ["block_23", [{"image_0": "1170_0.png", "coords": [96, 612, 330, 707]}]], ["block_24", [" 1157 \n"]]], "page_1171": [["block_0", [" 1158 \n"]], ["block_1", [" 111 . The Lewis structure is made from three units, but the atoms must be rearranged:\n"]], ["block_2", [" 113 . The molecular dipole points away from the hydrogen atoms.\n 115 . The structures are very similar. In the model mode, each electron group occupies the same amount of\n"]], ["block_3", [" Chapter 8 \n"]], ["block_4", [" 9 . Hybridization is introduced to explain the geometry of bonding orbitals in valance bond theory.\n 11 . There are no d orbitals in the valence shell of carbon.\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", [" 1 . Similarities: Both types of bonds result from overlap of atomic orbitals on adjacent atoms and contain a\n"]], ["block_7", [" 3 . The specific average bond distance is the distance with the lowest energy. At distances less than the bond\n"]], ["block_8", [" 5 . Bonding: One \u03c3 bond and one \u03c0 bond. The s orbitals are filled and do not overlap. The p orbitals overlap\n"]], ["block_9", [" 7 . No, two of the p orbitals (one on each N) will be oriented end-to-end and will form a \u03c3 bond.\n"]], ["block_10", ["maximum of two electrons. Differences: \u03c3 bonds are stronger and result from end-to-end overlap and all\nsingle bonds are \u03c3 bonds; \u03c0 bonds between the same two atoms are weaker because they result from side-\nby-side overlap, and multiple bonds contain one or more \u03c0 bonds (in addition to a \u03c3 bond).\n"]], ["block_11", ["distance, the positive charges on the two nuclei repel each other, and the overall energy increases.\n"]], ["block_12", ["along the axis to form a \u03c3 bond and side-by-side to form the \u03c0 bond.\n"]], ["block_13", [{"image_0": "1171_0.png", "coords": [89, 504, 440, 596]}]], ["block_14", [{"image_1": "1171_1.png", "coords": [89, 611, 323, 704]}]], ["block_15", [{"image_2": "1171_2.png", "coords": [96, 57, 447, 113]}]], ["block_16", ["(b)\n"]], ["block_17", [{"image_3": "1171_3.png", "coords": [96, 141, 213, 160]}]], ["block_18", ["(c)\n"]], ["block_19", [{"image_4": "1171_4.png", "coords": [96, 189, 213, 199]}]], ["block_20", ["(d)\nincludes three regions of electron density (all are bonds with no lone pairs); the shape is\n"]], ["block_21", ["trigonal planar; CS2 has only two regions of electron density (all bonds with no lone pairs); the shape is\nlinear\n"]], ["block_22", [{"image_5": "1171_5.png", "coords": [96, 265, 188, 318]}]], ["block_23", ["space, so the bond angle is shown as 109.5\u00b0. In the \u201creal\u201d mode, the lone pairs are larger, causing the\nhydrogens to be compressed. This leads to the smaller angle of 104.5\u00b0.\n"]]], "page_1172": [["block_0", [" 13 . trigonal planar, sp; trigonal pyramidal (one lone pair on A) sp; T-shaped (two lone pairs on A spd, or\n"]], ["block_1", [" 15 . (a) Each S has a bent (109\u00b0) geometry, sp\n"]], ["block_2", [" 17 . (a) XeF2\n"]], ["block_3", [" 19 . (a)\n"]], ["block_4", [" 21 .\n"]], ["block_5", ["(three lone pairs on A) spd\n"]], ["block_6", [{"image_0": "1172_0.png", "coords": [91, 95, 208, 177]}]], ["block_7", ["(b) Bent (120\u00b0), sp\n"]], ["block_8", [{"image_1": "1172_1.png", "coords": [91, 205, 325, 230]}]], ["block_9", ["(c) Trigonal planar, sp\n"]], ["block_10", [{"image_2": "1172_2.png", "coords": [91, 258, 208, 321]}]], ["block_11", ["(d) Tetrahedral, sp\n"]], ["block_12", [{"image_3": "1172_3.png", "coords": [91, 349, 208, 402]}]], ["block_13", ["(b)\n"]], ["block_14", [{"image_4": "1172_4.png", "coords": [91, 431, 208, 450]}]], ["block_15", ["(c) linear (d) spd\n"]], ["block_16", [{"image_5": "1172_5.png", "coords": [91, 490, 325, 565]}]], ["block_17", ["(b) P atoms, trigonal pyramidal; S atoms, bent, with two lone pairs; Cl atoms, trigonal pyramidal; (c)\nHybridization about P, S, and Cl is, in all cases, sp; (d) Oxidation states P +1, S\nCl +5, O \u20132. Formal\n"]], ["block_18", ["charges: P 0; S 0; Cl +2: O \u20131\n"]], ["block_19", [{"image_6": "1172_6.png", "coords": [91, 627, 325, 689]}]], ["block_20", ["Phosphorus and nitrogen can form sphybrids to form three bonds and hold one lone pair in PF3 and NF3,\nrespectively. However, nitrogen has no valence d orbitals, so it cannot form a set of spd hybrid orbitals to\nbind five fluorine atoms in NF5. Phosphorus has d orbitals and can bind five fluorine atoms with spd\n"]], ["block_21", [" 1159 \n"]]], "page_1173": [["block_0", [" 1160 \n"]], ["block_1", [" 23 . A triple bond consists of one \u03c3 bond and two \u03c0 bonds. A \u03c3 bond is stronger than a \u03c0 bond due to greater\n"]], ["block_2", [" 25 . (a)\n"]], ["block_3", [" 27 . (a) sp; (b) sp; (c) sp; (d) sp; (e) sp; (f) spd; (g) sp\n"]], ["block_4", [" 29 . (a) sp, delocalized; (b) sp, localized; (c) sp, delocalized; (d) sp, delocalized\n 31 .\n"]], ["block_5", [" 33 . (a) Similarities: Both are bonding orbitals that can contain a maximum of two electrons. Differences: \u03c3\n"]], ["block_6", [" 35 . An odd number of electrons can never be paired, regardless of the arrangement of the molecular orbitals.\n"]], ["block_7", [" 37 . Bonding orbitals have electron density in close proximity to more than one nucleus. The interaction\n"]], ["block_8", [" 39 . The pairing of the two bonding electrons lowers the energy of the system relative to the energy of the\n"]], ["block_9", [" 41 . (a) H2 bond order = 1,\nbond order = 0.5,\nbond order = 0.5, strongest bond is H2; (b) O2 bond\n"]], ["block_10", [" 43 . (a) H2; (b) N2; (c) O; (d) C2; (e) B2\n 45 . Yes, fluorine is a smaller atom than Li, so atoms in the 2s orbital are closer to the nucleus and more stable.\n 47 . 2+\n 49 . N2 has s-p mixing, so the \u03c0 orbitals are the last filled in\nO2 does not have s-p mixing, so the \u03c3p\n"]], ["block_11", [" Access for free at openstax.org \n"]], ["block_12", ["hybrid orbitals in PF5.\n"]], ["block_13", ["overlap.\n"]], ["block_14", [{"image_0": "1173_0.png", "coords": [91, 114, 325, 170]}]], ["block_15", ["(b) The terminal carbon atom uses sphybrid orbitals, while the central carbon atom is sp hybridized. (c)\nEach of the two \u03c0 bonds is formed by overlap of a 2p orbital on carbon and a nitrogen 2p orbital.\n"]], ["block_16", [{"image_1": "1173_1.png", "coords": [91, 243, 559, 387]}]], ["block_17", ["Each of the four electrons is in a separate orbital and overlaps with an electron on an oxygen atom.\n"]], ["block_18", ["orbitals are end-to-end combinations of atomic orbitals, whereas \u03c0 orbitals are formed by side-by-side\noverlap of orbitals. (b) Similarities: Both are quantum-mechanical constructs that represent the\nprobability of finding the electron about the atom or the molecule. Differences: \u03c8 for an atomic orbital\ndescribes the behavior of only one electron at a time based on the atom. For a molecule, \u03c8 represents a\nmathematical combination of atomic orbitals. (c) Similarities: Both are orbitals that can contain two\nelectrons. Differences: Bonding orbitals result in holding two or more atoms together. Antibonding\norbitals have the effect of destabilizing any bonding that has occurred.\n"]], ["block_19", ["It will always be paramagnetic.\n"]], ["block_20", ["between the bonding positively charged nuclei and negatively charged electrons stabilizes the system.\n"]], ["block_21", ["nonbonded electrons.\n"]], ["block_22", ["order = 2,\nbond order = 3;\nbond order = 1, strongest bond is\n(c) Li2 bond order = 1,\n"]], ["block_23", ["bond order = 0.5, Be2 bond order = 0, strongest bond is\n;(d) F2 bond order = 1,\nbond order = 1.5,\n"]], ["block_24", ["order = 2.5, strongest bond is N2\n"]], ["block_25", ["orbital fills before the \u03c0 orbitals.\n"]], ["block_26", ["bond order = 0.5, strongest bond is\n(e) N2 bond order = 3,\nbond order = 2.5,\nbond\n"]]], "page_1174": [["block_0", [" Chapter 9 \n"]], ["block_1", [" 11 . (a) 101.5 kPa; (b) 51 torr drop\n 13 . (a) 264 torr; (b) 35,200 Pa; (c) 0.352 bar\n 15 . (a) 623 mm Hg; (b) 0.820 atm; (c) 83.1 kPa\n 17 . With a closed-end manometer, no change would be observed, since the vaporized liquid would contribute\n"]], ["block_2", [" 19 . As the bubbles rise, the pressure decreases, so their volume increases as suggested by Boyle\u2019s law.\n 21 . (a) The number of particles in the gas increases as the volume increases. (b) temperature, pressure\n 23 . The curve would be farther to the right and higher up, but the same basic shape.\n 25 . About 12.5 L\n 27 . 3.40\n10torr\n"]], ["block_3", [" 29 . 12.1 L\n 31 . 217 L\n 33 . 8.190\n10mol; 5.553 g\n"]], ["block_4", [" 35 . (a) 7.24\n10g; (b) 23.1 g; (c) 1.5\n10g\n"]], ["block_5", [" 37 . 5561 L\n 39 . 46.4 g\n 41 . For a gas exhibiting ideal behavior:\n"]], ["block_6", [" 1 . The cutting edge of a knife that has been sharpened has a smaller surface area than a dull knife. Since\n"]], ["block_7", [" 3 . Lying down distributes your weight over a larger surface area, exerting less pressure on the ice compared\n"]], ["block_8", [" 5 . 0.809 atm; 82.0 kPa\n 7 . 2.2\n10kPa\n"]], ["block_9", [" 9 . Earth: 14.7 lb in; Venus: 1.30 \u00d7 10lb in\n"]], ["block_10", ["pressure is force per unit area, a sharp knife will exert a higher pressure with the same amount of force\nand cut through material more effectively.\n"]], ["block_11", ["to standing up. If you exert less pressure, you are less likely to break through thin ice.\n"]], ["block_12", ["equal, opposing pressures in both arms of the manometer tube. However, with an open-ended\nmanometer, a higher pressure reading of the gas would be obtained than expected, since Pgas = Patm + Pvol\n"]], ["block_13", ["liquid\n"]], ["block_14", [" 1161 \n"]]], "page_1175": [["block_0", [" 1162 \n"]], ["block_1", [" 43 . (a) 1.85 L CCl2F2; (b) 4.66 L CH3CH2F\n 45 . 0.644 atm\n 47 . The pressure decreases by a factor of 3.\n 49 . 4.64 g L\n"]], ["block_2", [" 51 . 38.8 g\n 53 . 72.0 g mol\n"]], ["block_3", [" 55 . 88.1 g mol; PF3\n 57 . 141 atm, 107,000 torr, 14,300 kPa\n 59 . CH4: 276 kPa; C2H6: 27 kPa; C3H8: 3.4 kPa\n 61 . Yes\n 63 . 740 torr\n 65 . (a) Determine the moles of HgO that decompose; using the chemical equation, determine the moles of O2\n"]], ["block_4", [" 67 . (a) Determine the molar mass of CCl2F2. From the balanced equation, calculate the moles of H2 needed for\n"]], ["block_5", [" 69 . (a) Balance the equation. Determine the grams of CO2 produced and the number of moles. From the ideal\n"]], ["block_6", [" 71 . 42.00 L\n 73 . (a) 18.0 L; (b) 0.533 atm\n 75 . 10.57 L O2\n"]], ["block_7", [" Access for free at openstax.org \n"]], ["block_8", [{"image_0": "1175_0.png", "coords": [91, 57, 559, 454]}]], ["block_9", ["produced by decomposition of this amount of HgO; and determine the volume of O2 from the moles of O2,\ntemperature, and pressure. (b) 0.308 L\n"]], ["block_10", ["the complete reaction. From the ideal gas law, convert moles of H2 into volume. (b) 3.72\n10L\n"]], ["block_11", ["gas law, determine the volume of gas. (b) 7.43\n10L\n"]]], "page_1176": [["block_0", [" 77 . 5.40\n10L\n"]], ["block_1", [" 79 . XeF4\n 81 . 4.2 hours\n 83 . Effusion can be defined as the process by which a gas escapes through a pinhole into a vacuum. Graham\u2019s\n"]], ["block_2", [" 85 . F2, N2O, Cl2, H2S\n 87 . 1.4; 1.2\n 89 . 51.7 cm\n 91 . Yes. At any given instant, there are a range of values of molecular speeds in a sample of gas. Any single\n"]], ["block_3", [" 93 . H2O. Cooling slows the speeds of the He atoms, causing them to behave as though they were heavier.\n 95 . (a) The number of collisions per unit area of the container wall is constant. (b) The average kinetic energy\n"]], ["block_4", [" 97 . (a) equal; (b) less than; (c) 29.48 g mol; (d) 1.0966 g L; (e) 0.129 g/L; (f) 4.01\n10g; net lifting capacity\n"]], ["block_5", [" 99 . Gases C, E, and F\n 101 . The gas behavior most like an ideal gas will occur under the conditions in (b). Molecules have high\n"]], ["block_6", [" 103 . SF6\n 105 . (a) A straight horizontal line at 1.0; (b) When real gases are at low pressures and high temperatures, they\n"]], ["block_7", [" Chapter 10 \n"]], ["block_8", [" 1 . Liquids and solids are similar in that they are matter composed of atoms, ions, or molecules. They are\n"]], ["block_9", [" 3 . They are similar in that the atoms or molecules are free to move from one position to another. They differ\n"]], ["block_10", ["incompressible and have similar densities that are both much larger than those of gases. They are\ndifferent in that liquids have no fixed shape, and solids are rigid.\n"]], ["block_11", ["in that the particles of a liquid are confined to the shape of the vessel in which they are placed. In contrast,\na gas will expand without limit to fill the space into which it is placed.\n"]], ["block_12", ["law states that with a mixture of two gases A and B:\nBoth A and B are in the\n"]], ["block_13", ["same container at the same temperature, and therefore will have the same kinetic energy:\n"]], ["block_14", ["Therefore,\n"]], ["block_15", ["molecule can speed up or slow down as it collides with other molecules. The average speed of all the\nmolecules is constant at constant temperature.\n"]], ["block_16", ["doubles. (c) The root mean square speed increases to\ntimes its initial value; urms is proportional to\n"]], ["block_17", ["= 384 lb; (g) 270 L; (h) 39.1 kJ min\n"]], ["block_18", ["speeds and move through greater distances between collision; they also have shorter contact times and\ninteractions are less likely. Deviations occur with the conditions described in (a) and (c). Under\nconditions of (a), some gases may liquefy. Under conditions of (c), most gases will liquefy.\n"]], ["block_19", ["behave close enough to ideal gases that they are approximated as such; however, in some cases, we see\nthat at a high pressure and temperature, the ideal gas approximation breaks down and is significantly\ndifferent from the pressure calculated by the ideal gas equation. (c) The greater the compressibility, the\nmore the volume matters. At low pressures, the correction factor for intermolecular attractions is more\nsignificant, and the effect of the volume of the gas molecules on Z would be a small lowering\ncompressibility. At higher pressures, the effect of the volume of the gas molecules themselves on Z would\nincrease compressibility (see Figure 9.35). (d) Once again, at low pressures, the effect of intermolecular\nattractions on Z would be more important than the correction factor for the volume of the gas molecules\nthemselves, though perhaps still small. At higher pressures and low temperatures, the effect of\nintermolecular attractions would be larger. See Figure 9.35. (e) Low temperatures\n"]], ["block_20", [" 1163 \n"]]], "page_1177": [["block_0", [" 1164 \n"]], ["block_1", [" 9 . The London forces typically increase as the number of electrons increase.\n 11 . (a) SiH4 < HCl < H2O; (b) F2 < Cl2 < Br2; (c) CH4 < C2H6 < C3H8; (d) N2 < O2 < NO\n 13 . Only rather small dipole-dipole interactions from C-H bonds are available to hold n-butane in the liquid\n"]], ["block_2", [" 15 . \u221285 \u00b0C. Water has stronger hydrogen bonds, so it melts at a higher temperature.\n 17 . The hydrogen bond between two hydrogen fluoride molecules is stronger than that between two water\n"]], ["block_3", [" 19 . H-bonding is the principle IMF holding the protein strands together. The H-bonding is between the\n"]], ["block_4", [" 21 . (a) hydrogen bonding, dipole-dipole attraction, and dispersion forces; (b) dispersion forces; (c) dipole-\n"]], ["block_5", [" 23 . The water molecules have strong intermolecular forces of hydrogen bonding. The water molecules are\n"]], ["block_6", [" 25 . Temperature has an effect on intermolecular forces: The higher the temperature, the greater the kinetic\n"]], ["block_7", [" 27 . (a) As the water reaches higher temperatures, the increased kinetic energies of its molecules are more\n"]], ["block_8", [" 29 . 1.7\n10m\n"]], ["block_9", [" 31 . The heat is absorbed by the ice, providing the energy required to partially overcome intermolecular\n"]], ["block_10", [" 33 . We can see the amount of liquid in an open container decrease and we can smell the vapor of some\n"]], ["block_11", [" 35 . The vapor pressure of a liquid decreases as the strength of its intermolecular forces increases.\n 37 . As the temperature increases, the average kinetic energy of the molecules of gasoline increases and so a\n"]], ["block_12", [" 39 . They are equal when the pressure of gas above the liquid is exactly 1 atm.\n 41 . approximately 95 \u00b0C\n 43 . (a) At 5000 feet, the atmospheric pressure is lower than at sea level, and water will therefore boil at a lower\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", [" 5 . All atoms and molecules will condense into a liquid or solid in which the attractive forces exceed the\n"]], ["block_15", [" 7 . (a) Dispersion forces occur as an atom develops a temporary dipole moment when its electrons are\n"]], ["block_16", ["kinetic energy of the molecules, at sufficiently low temperature.\n"]], ["block_17", ["distributed asymmetrically about the nucleus. This structure is more prevalent in large atoms such as\nargon or radon. A second atom can then be distorted by the appearance of the dipole in the first atom. The\nelectrons of the second atom are attracted toward the positive end of the first atom, which sets up a dipole\nin the second atom. The net result is rapidly fluctuating, temporary dipoles that attract one another (e.g.,\nAr). (b) A dipole-dipole attraction is a force that results from an electrostatic attraction of the positive end\nof one polar molecule for the negative end of another polar molecule (e.g., ICI molecules attract one\nanother by dipole-dipole interaction). (c) Hydrogen bonds form whenever a hydrogen atom is bonded to\none of the more electronegative atoms, such as a fluorine, oxygen, or nitrogen atom. The electrostatic\nattraction between the partially positive hydrogen atom in one molecule and the partially negative atom in\nanother molecule gives rise to a strong dipole-dipole interaction called a hydrogen bond (e.g.,\n"]], ["block_18", ["state. Chloroethane, however, has rather large dipole interactions because of the Cl-C bond; the\ninteraction, therefore, is stronger, leading to a higher boiling point.\n"]], ["block_19", ["molecules because the electronegativity of F is greater than that of O. Consequently, the partial negative\ncharge on F is greater than that on O. The hydrogen bond between the partially positive H and the larger\npartially negative F will be stronger than that formed between H and O.\n"]], ["block_20", ["and\n"]], ["block_21", ["dipole attraction and dispersion forces\n"]], ["block_22", ["thus attracted strongly to one another and exhibit a relatively large surface tension, forming a type of\n\u201cskin\u201d at its surface. This skin can support a bug or paper clip if gently placed on the water.\n"]], ["block_23", ["energies of the molecules and the greater the extent to which their intermolecular forces are overcome,\nand so the more fluid (less viscous) the liquid. The lower the temperature, the less the intermolecular\nforces are overcome, and so the less viscous the liquid.\n"]], ["block_24", ["effective in overcoming hydrogen bonding, and so its surface tension decreases. Surface tension and\nintermolecular forces are directly related. (b) The same trend in viscosity is seen as in surface tension,\nand for the same reason.\n"]], ["block_25", ["attractive forces in the solid and causing a phase transition to liquid water. The solution remains at 0 \u00b0C\nuntil all the ice is melted. Only the amount of water existing as ice changes until the ice disappears. Then\nthe temperature of the water can rise.\n"]], ["block_26", ["liquids.\n"]], ["block_27", ["greater fraction of molecules have sufficient energy to escape from the liquid than at lower temperatures.\n"]], ["block_28", ["temperature. This lower temperature will cause the physical and chemical changes involved in cooking\nthe egg to proceed more slowly, and a longer time is required to fully cook the egg. (b) As long as the air\n"]]], "page_1178": [["block_0", [" 45 . Dispersion forces increase with molecular mass or size. As the number of atoms composing the molecules\n"]], ["block_1", [" 47 . The boiling point of CS2 is higher than that of CO2 partially because of the higher molecular weight of CS2;\n"]], ["block_2", [" 49 . The thermal energy (heat) needed to evaporate the liquid is removed from the skin.\n 51 . 1130 kJ\n 53 . (a) 13.0 kJ; (b) It is likely that the heat of vaporization will have a larger magnitude since in the case of\n"]], ["block_3", [" 55 . At low pressures and 0.005 \u00b0C, the water is a gas. As the pressure increases to 4.6 torr, the water becomes\n"]], ["block_4", [" 57 . (a) gas; (b) gas; (c) gas; (d) gas; (e) solid; (f) gas\n 59 .\n"]], ["block_5", [" 61 . Yes, ice will sublime, although it may take it several days. Ice has a small vapor pressure, and some ice\n"]], ["block_6", [" 63 . (a)\n"]], ["block_7", ["surrounding the body contains less water vapor than the maximum that air can hold at that temperature,\nperspiration will evaporate, thereby cooling the body by removing the heat of vaporization required to\nvaporize the water.\n"]], ["block_8", ["in this homologous series increases, so does the extent of intermolecular attraction via dispersion forces\nand, consequently, the energy required to overcome these forces and vaporize the liquids.\n"]], ["block_9", ["consequently, the attractive forces are stronger in CS2. It would be expected, therefore, that the heat of\nvaporization would be greater than that of 9.8 kJ/mol for CO2. A value of 28 kJ/mol would seem\nreasonable. A value of \u22128.4 kJ/mol would indicate a release of energy upon vaporization, which is clearly\nimplausible.\n"]], ["block_10", ["vaporization the intermolecular interactions have to be completely overcome, while melting weakens or\ndestroys only some of them.\n"]], ["block_11", ["a solid; as the pressure increases still more, it becomes a liquid. At 40 \u00b0C, water at low pressure is a vapor;\nat pressures higher than about 75 torr, it converts into a liquid. At \u221240 \u00b0C, water goes from a gas to a solid\nas the pressure increases above very low values.\n"]], ["block_12", [{"image_0": "1178_0.png", "coords": [91, 334, 325, 463]}]], ["block_13", ["molecules form gas and escape from the ice crystals. As time passes, more and more solid converts to gas\nuntil eventually the clothes are dry.\n"]], ["block_14", [" 1165 \n"]]], "page_1179": [["block_0", [" 1166 \n"]], ["block_1", [" Access for free at openstax.org \n"]], ["block_2", [{"image_0": "1179_0.png", "coords": [91, 57, 325, 321]}]], ["block_3", ["(b)\n"]], ["block_4", [{"image_1": "1179_1.png", "coords": [91, 349, 325, 613]}]], ["block_5", ["(c)\n"]]], "page_1180": [["block_0", [" 65 . (e) molecular crystals\n 67 . Ice has a crystalline structure stabilized by hydrogen bonding. These intermolecular forces are of\n"]], ["block_1", [" 69 . (a) ionic; (b) covalent network; (c) molecular; (d) metallic; (e) covalent network; (f) molecular; (g)\n"]], ["block_2", [{"image_0": "1180_0.png", "coords": [91, 57, 325, 321]}]], ["block_3", ["(d)\n"]], ["block_4", [{"image_1": "1180_1.png", "coords": [91, 349, 325, 614]}]], ["block_5", ["(e) liquid phase (f) sublimation\n"]], ["block_6", ["comparable strength and thus require the same amount of energy to overcome. As a result, ice melts at a\nsingle temperature and not over a range of temperatures. The various, very large molecules that compose\nbutter experience varied van der Waals attractions of various strengths that are overcome at various\ntemperatures, and so the melting process occurs over a wide temperature range.\n"]], ["block_7", [" 1167 \n"]]], "page_1181": [["block_0", [" 1168 \n"]], ["block_1", [" 71 . X = ionic; Y = metallic; Z = covalent network\n 73 . (b) metallic solid\n 75 . The structure of this low-temperature form of iron (below 910 \u00b0C) is body-centered cubic. There is one-\n"]], ["block_2", [" 77 . eight\n 79 . 12\n 81 . (a) 1.370 \u00c5; (b) 19.26 g/cm\n 83 . (a) 2.176 \u00c5; (b) 3.595 g/cm\n"]], ["block_3", [" 85 . The crystal structure of Si shows that it is less tightly packed (coordination number 4) in the solid than Al\n"]], ["block_4", [" 87 . In a closest-packed array, two tetrahedral holes exist for each anion. If only half the tetrahedral holes are\n"]], ["block_5", [" 89 . Co3O4\n 91 . In a simple cubic array, only one cubic hole can be occupied be a cation for each anion in the array. The\n"]], ["block_6", [" 93 . 59.95%; The oxidation number of titanium is +4.\n 95 . Both ions are close in size: Mg, 0.65; Li, 0.60. This similarity allows the two to interchange rather easily.\n"]], ["block_7", [" 97 . Mn2O3\n 99 . 1.48 \u00c5\n 101 . 2.874 \u00c5\n 103 . 20.2\u00b0\n 105 . 1.74\n10eV\n"]], ["block_8", [" Chapter 11 \n"]], ["block_9", [" 11 . (a) Fe(NO3)3 is a strong electrolyte, thus it should completely dissociate into Feand\nions.\n"]], ["block_10", [" 13 . (a) high conductivity (solute is an ionic compound that will dissociate when dissolved); (b) high\n"]], ["block_11", [" 15 . (a) ion-dipole; (b) hydrogen bonds; (c) dispersion forces; (d) dipole-dipole attractions; (e) dispersion forces\n 17 . The solubility of solids usually decreases upon cooling a solution, while the solubility of gases usually\n"]], ["block_12", [" 19 . 40%\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", [" 1 . A solution can vary in composition, while a compound cannot vary in composition. Solutions are\n"]], ["block_15", [" 3 . (a) The process is endothermic as the solution is consuming heat. (b) Attraction between the Kand\n"]], ["block_16", [" 5 . (a) ion-dipole forces; (b) dipole-dipole forces; (c) dispersion forces; (d) dispersion forces; (e) hydrogen\n"]], ["block_17", [" 7 . Heat is released when the total intermolecular forces (IMFs) between the solute and solvent molecules are\n"]], ["block_18", [" 9 . Crystals of NaCl dissolve in water, a polar liquid with a very large dipole moment, and the individual ions\n"]], ["block_19", ["homogeneous at the molecular level, while other mixtures are heterogeneous.\n"]], ["block_20", ["ions is stronger than between the ions and water molecules (the ion-ion interactions have a lower, more\nnegative energy). Therefore, the dissolution process increases the energy of the molecular interactions,\nand it consumes the thermal energy of the solution to make up for the difference. (c) No, an ideal solution\nis formed with no appreciable heat release or consumption.\n"]], ["block_21", ["bonding\n"]], ["block_22", ["stronger than the total IMFs in the pure solute and in the pure solvent: Breaking weaker IMFs and forming\nstronger IMFs releases heat. Heat is absorbed when the total IMFs in the solution are weaker than the total\nof those in the pure solute and in the pure solvent: Breaking stronger IMFs and forming weaker IMFs\nabsorbs heat.\n"]], ["block_23", ["become strongly solvated. Hexane is a nonpolar liquid with a dipole moment of zero and, therefore, does\nnot significantly interact with the ions of the NaCl crystals.\n"]], ["block_24", ["molecular; (h) ionic; (i) ionic\n"]], ["block_25", ["eighth atom at each of the eight corners of the cube and one atom in the center of the cube.\n"]], ["block_26", ["(coordination number 12).\n"]], ["block_27", ["occupied, the numbers of anions and cations are equal. The formula for cadmium sulfide is CdS.\n"]], ["block_28", ["ratio of thallium to iodide must be 1:1; therefore, the formula for thallium is TlI.\n"]], ["block_29", ["The difference in charge is generally compensated by the switch of Sifor Al.\n"]], ["block_30", ["Therefore, (z) best represents the solution. (b)\n"]], ["block_31", ["conductivity (solute is a strong acid and will ionize completely when dissolved); (c) nonconductive (solute\nis a covalent compound, neither acid nor base, unreactive towards water); (d) low conductivity (solute is a\nweak base and will partially ionize when dissolved)\n"]], ["block_32", ["decreases upon heating.\n"]]], "page_1182": [["block_0", [" 21 . 2.8 g\n 23 . 2.9 atm\n 25 . 102 L HCl\n 27 . The strength of the bonds between like molecules is stronger than the strength between unlike molecules.\n"]], ["block_1", [" 29 . Both form homogeneous solutions; their boiling point elevations are the same, as are their lowering of\n"]], ["block_2", [" 31 . (a) Find number of moles of HNO3 and H2O in 100 g of the solution. Find the mole fractions for the\n"]], ["block_3", [" 33 . (a)\n(b)\n(c)\n"]], ["block_4", [" 35 . In a 1 M solution, the mole is contained in exactly 1 L of solution. In a 1 m solution, the mole is contained\n"]], ["block_5", [" 37 . (a) Determine the molar mass of HNO3. Determine the number of moles of acid in the solution. From the\n"]], ["block_6", [" 39 . (a) 6.70\n10m; (b) 5.67 m; (c) 2.8 m; (d) 0.0358 m\n"]], ["block_7", [" 41 . 1.08 m\n 43 . (a) Determine the molar mass of sucrose; determine the number of moles of sucrose in the solution;\n"]], ["block_8", [" 45 . (a) Determine the molar mass of sucrose; determine the number of moles of sucrose in the solution;\n"]], ["block_9", [" 47 . (a) Determine the molar mass of Ca(NO3)2; determine the number of moles of Ca(NO3)2 in the solution;\n"]], ["block_10", [" 49 . (a) Determine the molal concentration from the change in boiling point and Kb; determine the moles of\n"]], ["block_11", [" 51 . No. Pure benzene freezes at 5.5 \u00b0C, and so the observed freezing point of this solution is depressed by \u0394Tf\n"]], ["block_12", [" 53 . 144 g mol\n"]], ["block_13", [" 55 . 0.870 \u00b0C\n 57 . S8\n 59 . 1.39\n10g mol\n"]], ["block_14", [" 61 . 54 g\n 63 . 100.26 \u00b0C\n 65 . (a)\n(b) Vapor pressures are: CH3OH: 55 torr; C2H5OH: 18 torr; (c)\n"]], ["block_15", [" 67 . The ions and compounds present in the water in the beef lower the freezing point of the beef below \u22121 \u00b0C.\n"]], ["block_16", [" 69 .\n"]], ["block_17", ["Therefore, some regions will exist in which the water molecules will exclude oil molecules and other\nregions will exist in which oil molecules will exclude water molecules, forming a heterogeneous region.\n"]], ["block_18", ["vapor pressures. Osmotic pressure and the lowering of the freezing point are also the same for both\nsolutions.\n"]], ["block_19", ["components. (b) The mole fraction of HNO3 is 0.378. The mole fraction of H2O is 0.622.\n"]], ["block_20", ["in exactly 1 kg of solvent.\n"]], ["block_21", ["number of moles and the mass of solvent, determine the molality. (b) 33.7 m\n"]], ["block_22", ["convert the mass of solvent to units of kilograms; from the number of moles and the mass of solvent,\ndetermine the molality; determine the difference between the boiling point of water and the boiling point\nof the solution; determine the new boiling point. (b) 100.5 \u00b0C\n"]], ["block_23", ["convert the mass of solvent to units of kilograms; from the number of moles and the mass of solvent,\ndetermine the molality; determine the difference between the freezing temperature of water and the\nfreezing temperature of the solution; determine the new freezing temperature. (b) \u22121.8 \u00b0C\n"]], ["block_24", ["determine the number of moles of ions in the solution; determine the molarity of ions, then the osmotic\npressure. (b) 2.67 atm\n"]], ["block_25", ["solute in the solution from the molal concentration and mass of solvent; determine the molar mass from\nthe number of moles and the mass of solute. (b) 2.1\n10g mol\n"]], ["block_26", ["= 5.5 \u2212 0.4 = 5.1 \u00b0C. The value computed, assuming no ionization of HCl, is \u0394Tf = (1.0 m)(5.14 \u00b0C/m) = 5.1\n\u00b0C. Agreement of these values supports the assumption that HCl is not ionized.\n"]], ["block_27", ["CH3OH: 0.75; C2H5OH: 0.25\n"]], ["block_28", ["The observed change equals the theoretical change; therefore, no dissociation occurs.\n"]], ["block_29", ["(d)\n"]], ["block_30", [" 1169 \n"]]], "page_1183": [["block_0", [" 1170 \n"]], ["block_1", [" 71 .\n"]], ["block_2", [" 73 . Colloidal dispersions consist of particles that are much bigger than the solutes of typical solutions.\n"]], ["block_3", [" 75 . If they are placed in an electrolytic cell, dispersed particles will move toward the electrode that carries a\n"]], ["block_4", [" Chapter 12 \n"]], ["block_5", [" 11 . (a) very slow; (b) As the temperature is increased, the reaction proceeds at a faster rate. The amount of\n"]], ["block_6", [" 13 . (a) 2; (b) 1\n 15 . (a) The process reduces the rate by a factor of 4. (b) Since CO does not appear in the rate law, the rate is not\n"]], ["block_7", [" 17 . 4.3\n10mol/L/s\n"]], ["block_8", [" Access for free at openstax.org \n"]], ["block_9", [" 1 . The instantaneous rate is the rate of a reaction at any particular point in time, a period of time that is so\n"]], ["block_10", [" 3 .\n"]], ["block_11", [" 5 . (a) average rate, 0 \u2212 10 s = 0.0375 mol Ls; average rate, 10 \u2212 20 s = 0.0265 mol Ls; (b)\n"]], ["block_12", [" 7 . Higher molarity increases the rate of the reaction. Higher temperature increases the rate of the reaction.\n"]], ["block_13", [" 9 . (a) Depending on the angle selected, the atom may take a long time to collide with the molecule and, when\n"]], ["block_14", ["short that the concentrations of reactants and products change by a negligible amount. The initial rate is\nthe instantaneous rate of reaction as it starts (as product just begins to form). Average rate is the average of\nthe instantaneous rates over a time period.\n"]], ["block_15", ["instantaneous rate, 15 s = 0.023 mol Ls; (c) average rate for B formation = 0.0188 mol Ls;\ninstantaneous rate for B formation = 0.012 mol Ls\n"]], ["block_16", ["Smaller pieces of magnesium metal will react more rapidly than larger pieces because more reactive\nsurface exists.\n"]], ["block_17", ["a collision does occur, it may not result in the breaking of the bond and the forming of the other. (b)\nParticles of reactant must come into contact with each other before they can react.\n"]], ["block_18", ["Colloidal particles are either very large molecules or aggregates of smaller species that usually are big\nenough to scatter light. Colloids are homogeneous on a macroscopic (visual) scale, while solutions are\nhomogeneous on a microscopic (molecular) scale.\n"]], ["block_19", ["charge opposite to their own charge. At this electrode, the charged particles will be neutralized and will\ncoagulate as a precipitate.\n"]], ["block_20", ["reactants decreases, and the amount of products increases. After a while, there is a roughly equal amount\nof BC, AB, and C in the mixture and a slight excess of A.\n"]], ["block_21", ["affected.\n"]], ["block_22", [" Colloidal System \n Dispersed Phase \n Dispersion Medium \n"]], ["block_23", ["starch dispersion\nstarch\nwater\n"]], ["block_24", ["smoke\nsolid particles\nair\n"]], ["block_25", ["fog\nwater\nair\n"]], ["block_26", ["pearl\nwater\ncalcium carbonate (CaCO3)\n"]], ["block_27", ["whipped cream\nair\ncream\n"]], ["block_28", ["floating soap\nair\nsoap\n"]], ["block_29", ["jelly\nfruit juice\npectin gel\n"]], ["block_30", ["milk\nbutterfat\nwater\n"]], ["block_31", ["ruby\nchromium(III) oxide (Cr2O3)\naluminum oxide (Al2O3)\n"]]], "page_1184": [["block_0", [" 19 . 7.9\n10mol/L/year\n"]], ["block_1", [" 21 . rate = k; k = 2.0\n10mol Lh(about 0.9 g Lhfor the average male); The reaction is zero order.\n"]], ["block_2", [" 23 . rate = k[NOCl]; k = 8.0\n10L/mol/h; second order\n"]], ["block_3", [" 25 . rate = k[NO][Cl2]; k = 9.1 Lmolh; second order in NO; first order in Cl2\n 27 . (a) The rate law is second order in A and is written as rate = k[A]. (b) k = 7.88\n10L mols\n"]], ["block_4", [" 29 . (a) 2.5\n10mol/L/min\n"]], ["block_5", [" 31 . rate = k[I][OCl]; k = 6.1\n10L mol s\n"]], ["block_6", [" 33 . Plotting a graph of ln[SO2Cl2] versus t reveals a linear trend; therefore we know this is a first-order\n"]], ["block_7", ["k = 2.20\n10s\n"]], ["block_8", ["reaction:\n"]], ["block_9", [{"image_0": "1184_0.png", "coords": [91, 171, 416, 425]}]], ["block_10", [" 1171 \n"]]], "page_1185": [["block_0", [" 1172 \n"]], ["block_1", [" 34 .\n"]], ["block_2", [" 36 . 14.3 d\n 38 . 8.3\n10s\n"]], ["block_3", [" 40 . 0.826 s\n 42 . The reaction is first order. k = 1.0\n10L molmin\n"]], ["block_4", [" 44 . 1.16 \u00d7 10s ; 20% remains\n 46 . 252 days\n 48 .\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", [{"image_0": "1185_0.png", "coords": [91, 63, 325, 391]}]], ["block_7", ["The plot is nicely linear, so the reaction is second order. k = 50.1 L molh\n"]], ["block_8", [" [A] 0 (M) \n k \n 10 3 (s \u22121 ) \n"]], ["block_9", ["4.88\n2.45\n"]], ["block_10", ["3.52\n2.51\n"]], ["block_11", ["2.29\n2.53\n"]], ["block_12", ["1.81\n2.58\n"]], ["block_13", ["5.33\n2.36\n"]], ["block_14", ["4.05\n2.47\n"]], ["block_15", ["2.95\n2.48\n"]]], "page_1186": [["block_0", [" 50 . The reactants either may be moving too slowly to have enough kinetic energy to exceed the activation\n"]], ["block_1", [" 52 . The activation energy is the minimum amount of energy necessary to form the activated complex in a\n"]], ["block_2", [" 54 . After finding k at several different temperatures, a plot of ln k versus\ngives a straight line with the slope\n"]], ["block_3", [" 56 . (a) 4-times faster (b) 128-times faster\n 58 .\n 60 . 43.0 kJ/mol\n 62 . 177 kJ/mol\n 64 . Ea = 108 kJ; A = 2.0\n10s; k = 3.2\n10s; (b) 1.81\n10h or 7.6\n10day; (c) Assuming that the\n"]], ["block_4", [" 66 . The A atom has enough energy to react with BC; however, the different angles at which it bounces off of BC\n"]], ["block_5", [" 68 . No. In general, for the overall reaction, we cannot predict the effect of changing the concentration without\n"]], ["block_6", [" 70 . Rate = k[A][B]; Rate = k[A]\n"]], ["block_7", [" 72 . (a) Rate1 = k[O3]; (b) Rate2 = k[O3][Cl]; (c) Rate3 = k[ClO][O]; (d) Rate2 = k[O3][NO]; (e) Rate3 = k[NO2][O]\n 74 . (a) Doubling [H2] doubles the rate. [H2] must enter the rate law to the first power. Doubling [NO] increases\n"]], ["block_8", [" 76 . The general mode of action for a catalyst is to provide a mechanism by which the reactants can unite more\n"]], ["block_9", [" 78 . (a) Chlorine atoms are a catalyst because they react in the second step but are regenerated in the third\n"]], ["block_10", [" 80 . The lowering of the transition state energy indicates the effect of a catalyst. (a) B; (b) B\n 82 . The energy needed to go from the initial state to the transition state is (a) 10 kJ; (b) 10 kJ.\n 84 . Both diagrams describe two-step, exothermic reactions, but with different changes in enthalpy, suggesting\n"]], ["block_11", [" Chapter 13 \n"]], ["block_12", [" 1 . The reaction can proceed in both the forward and reverse directions.\n 3 . When a system has reached equilibrium, no further changes in the reactant and product concentrations\n"]], ["block_13", [" 5 . Not necessarily. A system at equilibrium is characterized by constant reactant and product\n"]], ["block_14", [" 7 . Equilibrium cannot be established between the liquid and the gas phase if the top is removed from the\n"]], ["block_15", ["occur; the forward and reverse reactions continue to proceed, but at equal rates.\n"]], ["block_16", ["concentrations, but the values of the reactant and product concentrations themselves need not be equal.\n"]], ["block_17", ["energy for the reaction, or the orientation of the molecules when they collide may prevent the reaction\nfrom occurring.\n"]], ["block_18", ["reaction. It is usually expressed as the energy necessary to form one mole of activated complex.\n"]], ["block_19", ["reaction is irreversible simplifies the calculation because we do not have to account for any reactant that,\nhaving been converted to product, returns to the original state.\n"]], ["block_20", ["without reacting indicate that the orientation of the molecule is an important part of the reaction kinetics\nand determines whether a reaction will occur.\n"]], ["block_21", ["knowing the rate law. Yes. If the reaction is an elementary reaction, then doubling the concentration of A\ndoubles the rate.\n"]], ["block_22", ["the rate by a factor of 4. [NO] must enter the rate law to the second power. (b) Rate = k [NO][H2]; (c) k = 5.0\n"]], ["block_23", ["adequate amount, steps 1 and 2 combine to give\nThis reaction corresponds\n"]], ["block_24", ["to the observed rate law. Combine steps 1 and 2 with step 3, which occurs by supposition in a rapid\nfashion, to give the appropriate stoichiometry.\n"]], ["block_25", ["readily by taking a path with a lower reaction energy. The rates of both the forward and the reverse\nreactions are increased, leading to a faster achievement of equilibrium.\n"]], ["block_26", ["step. Thus, they are not used up, which is a characteristic of catalysts. (b) NO is a catalyst for the same\nreason as in part (a).\n"]], ["block_27", ["the diagrams depict two different overall reactions.\n"]], ["block_28", ["10molLmin; (d) 0.0050 mol/L; (e) Step II is the rate-determining step. If step I gives N2O2 in\n"]], ["block_29", ["from which Ea may be determined.\n"]], ["block_30", [" [A] 0 (M) \n k \n 10 3 (s \u22121 ) \n"]], ["block_31", ["1.72\n2.43\n"]], ["block_32", [" 1173 \n"]]], "page_1187": [["block_0", [" 1174 \n"]], ["block_1", [" 11 . Since\na value of Kc \u2248 10 means that C6H6 predominates over C2H2. In such a case, the\n"]], ["block_2", [" 13 . Kc > 1\n"]], ["block_3", [" 15 . (a)\n(b)\n(c)\n(d) Qc = [SO2]; (e)\n(f)\n"]], ["block_4", [" 17 . (a) Qc 25 proceeds left; (b) QP 0.22 proceeds right; (c) Qc undefined proceeds left; (d) QP 1.00 proceeds\n"]], ["block_5", [" 19 . The system will shift toward the reactants to reach equilibrium.\n 21 . (a) homogenous; (b) homogenous; (c) homogenous; (d) heterogeneous; (e) heterogeneous; (f) homogenous;\n"]], ["block_6", [" 23 . This situation occurs in (a) and (b).\n 25 . (a) KP = 1.6\n10; (b) KP = 50.2; (c) Kc = 5.34\n10; (d) Kc = 4.60\n10\n"]], ["block_7", [" 27 .\n"]], ["block_8", [" 29 .\n"]], ["block_9", [" 31 . The amount of CaCO3 must be so small that\nis less than KP when the CaCO3 has completely\n"]], ["block_10", [" 33 . The change in enthalpy may be used. If the reaction is exothermic, the heat produced can be thought of as\n"]], ["block_11", [" 34 . No, it is not at equilibrium. Because the system is not confined, products continuously escape from the\n"]], ["block_12", [" 36 . Add N2; add H2; decrease the container volume; heat the mixture.\n 38 . (a) T increase = shift right, V decrease = shift left; (b) T increase = shift right, V = no effect; (c) T increase =\n"]], ["block_13", [" 40 . (a)\n(b) [H2] increases, [CO] decreases, [CH3OH] increases; (c), [H2] increases, [CO]\n"]], ["block_14", [" 42 . (a)\n(b) [H2O] no change, [CO] no change, [H2] no change; (c) [H2O] decreases, [CO]\n"]], ["block_15", [" 44 . Only (b)\n 46 . Add NaCl or some other salt that produces Clto the solution. Cooling the solution forces the equilibrium\n"]], ["block_16", [" 48 . Though the solution is saturated, the dynamic nature of the solubility equilibrium means the opposing\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", [" 9 . (a) Kc = [Ag][Cl] < 1. AgCl is insoluble; thus, the concentrations of ions are much less than 1 M; (b)\n"]], ["block_19", ["bottle because the system is not closed; one of the components of the equilibrium, the Br2 vapor, would\nescape from the bottle until all liquid disappeared. Thus, more liquid would evaporate than can condense\nback from the gas phase to the liquid phase.\n"]], ["block_20", ["of ions to a low level (<1 M).\n"]], ["block_21", ["reaction would be commercially feasible if the rate to equilibrium is suitable.\n"]], ["block_22", ["right; (e) QP 0 proceeds right; (f) Qc 4 proceeds left\n"]], ["block_23", ["(g) heterogeneous; (h) heterogeneous\n"]], ["block_24", ["decomposed. In other words, the starting amount of CaCO3 cannot completely generate the full\n"]], ["block_25", ["required for equilibrium.\n"]], ["block_26", ["a product. If the reaction is endothermic the heat added can be thought of as a reactant. Additional heat\nwould shift an exothermic reaction back to the reactants but would shift an endothermic reaction to the\nproducts. Cooling an exothermic reaction causes the reaction to shift toward the product side; cooling an\nendothermic reaction would cause it to shift to the reactants\u2019 side.\n"]], ["block_27", ["region of the flame; reactants are also added continuously from the burner and surrounding atmosphere.\n"]], ["block_28", ["shift left, V decrease = shift left; (d) T increase = shift left, V decrease = shift right.\n"]], ["block_29", ["decreases, [CH3OH] decreases; (d), [H2] increases, [CO] increases, [CH3OH] increases; (e), [H2] increases,\n[CO] increases, [CH3OH] decreases; (f), no changes.\n"]], ["block_30", ["decreases, [H2] decreases; (d) [H2O] increases, [CO] increases, [H2] decreases; (e) [H2O] decreases, [CO]\nincreases, [H2] increases. In (b), (c), (d), and (e), the mass of carbon will change, but its concentration\n(activity) will not change.\n"]], ["block_31", ["to the right, precipitating more AgCl(s).\n"]], ["block_32", ["processes of solid dissolution and precipitation continue to occur (just at equal rates, meaning the\ndissolved ion concentrations and the amount of undissolved solid remain constant). The radioactive Ag\n"]], ["block_33", ["(g)\n(h) Qc = [H2O]\n"]], ["block_34", ["> 1 because PbCl2 is insoluble and formation of the solid will reduce the concentration\n"]]], "page_1188": [["block_0", [" 50 .\n[A] = 0.1 M, [B] = 0.1 M, [C] = 1 M; and [A] = 0.01, [B] = 0.250, [C] = 0.791.\n"]], ["block_1", [" 52 . Kc = 6.00\n10\n"]], ["block_2", [" 54 . Kc = 0.50\n 56 . KP = 1.9\n10\n"]], ["block_3", [" 58 . KP = 3.06\n 60 . (a) \u22122x, +2x; (b)\n,\n, \u22122x; (c) \u22122x, 3x; (d) x, \u2013x, \u22123x; (e) +x; (f)\n"]], ["block_4", [" 62 . Activities of pure crystalline solids equal 1 and are constant; however, the mass of Ni does change.\n 64 . [NH3] = 9.1\n10M\n"]], ["block_5", [" 66 . PBrCl = 4.9\n10atm\n"]], ["block_6", [" 68 . [CO] = 2.04\n10M\n"]], ["block_7", [" 70 .\n"]], ["block_8", [" 72 . Calculate Q based on the calculated concentrations and see if it is equal to Kc. Because Q does equal 4.32,\n"]], ["block_9", [" 74 . (a) [NO2] = 1.17\n10M; [N2O4] = 0.128 M; (b) The assumption that x is negligibly small compared to\n"]], ["block_10", [" 76 . (a) [H2S] = 0.810 atm, [H2] = 0.014 atm, [S2] = 0.0072 atm; (b) The assumption that 2x is negligibly small\n"]], ["block_11", [" 78 . [PCl5] = 1.80 M; [Cl2] = 0.195 M; [PCl3] = 0.195 M.\n 79 . 507 g\n 81 . 330 g\n 84 . (a) 0.33 mol. (b) [CO2] = 0.50 M. Added H2 forms some water as a result of a shift to the left after H2 is\n"]], ["block_12", [" 86 . (a)\n(b) [NH3] must increase for Qc to reach Kc. (c) The increase in system volume\n"]], ["block_13", [" 88 .\n"]], ["block_14", [" Chapter 14 \n"]], ["block_15", [" 11 . Amphiprotic species may either gain or lose a proton in a chemical reaction, thus acting as a base or an\n"]], ["block_16", [" 13 . amphiprotic: (a)\n(b)\n"]], ["block_17", [" 1 . One example for NH3 as a conjugate acid:\nas a conjugate base:\n"]], ["block_18", [" 3 . (a)\n(b)\n(c)\n"]], ["block_19", [" 5 . (a)\n(b)\n(c)\n"]], ["block_20", [" 7 . (a) H2O, O; (b) H3O, OH; (c) H2CO3,\n(d)\n(e) H2SO4,\n(f)\n(g)\n"]], ["block_21", [" 9 . The labels are Br\u00f8nsted-Lowry acid = BA; its conjugate base = CB; Br\u00f8nsted-Lowry base = BB; its conjugate\n"]], ["block_22", ["H2S; S; (h)\nH4N2\n"]], ["block_23", ["acid = CA. (a) HNO3(BA), H2O(BB), H3O(CA),\n(b) CN(BB), H2O(BA), HCN(CA), OH(CB); (c)\n"]], ["block_24", ["H2SO4(BA), Cl(BB), HCl(CA),\n(d)\nOH(BB),\n(CB), H2O(CA); (e) O(BB),\n"]], ["block_25", ["H2O(BA) OH(CB and CA); (f) [Cu(H2O)3(OH)](BB), [Al(H2O)6](BA), [Cu(H2O)4](CA), [Al(H2O)5(OH)](CB);\n(g) H2S(BA),\nHS(CB), NH3(CA)\n"]], ["block_26", ["ions detected in the solution phase come from dissolution of the added solid, and their presence is\ncountered by precipitation of nonradioactive Ag.\n"]], ["block_27", ["the system must be at equilibrium.\n"]], ["block_28", ["0.129 is confirmed by comparing the initial concentration of the N2O4 to its concentration at equilibrium\n(they differ by just 1 in the least significant digit\u2019s place).\n"]], ["block_29", ["compared to 0.824 is confirmed by comparing the initial concentration of the H2S to its concentration at\nequilibrium (0.824 atm versus 0.810 atm, a difference of less than 2%).\n"]], ["block_30", ["added.\n"]], ["block_31", ["would lower the partial pressures of all reactants (including NO2). (d)\n"]], ["block_32", ["acid. An example is H2O. As an acid:\nAs a base:\n"]], ["block_33", ["(f)\n"]], ["block_34", ["(d)\n(e)\n"]], ["block_35", ["(f)\n"]], ["block_36", ["(d)\n(e)\n"]], ["block_37", [" 1175 \n"]]], "page_1189": [["block_0", [" 1176 \n"]], ["block_1", [" 15 . In a neutral solution [H3O] = [OH]. At 40 \u00b0C, [H3O] = [OH] = (2.910 \u00d7 10)= 1.7\n10.\n"]], ["block_2", [" 17 . x = 3.051\n10M = [H3O] = [OH]; pH = \u2212log3.051\n10= \u2212(\u22126.5156) = 6.5156; pOH = pH = 6.5156\n"]], ["block_3", [" 19 . (a) pH = 3.587; pOH = 10.413; (b) pOH = 0.68; pH = 13.32; (c) pOH = 3.85; pH = 10.15; (d) pOH = \u22120.40; pH\n"]], ["block_4", [" 21 . [H3O] = 3.0\n10M; [OH] = 3.3\n10M\n"]], ["block_5", [" 23 . [H3O] = 1\n10M; [OH] = 1\n10M\n"]], ["block_6", [" 25 . [OH] = 3.1\n10M\n"]], ["block_7", [" 27 . The salt ionizes in solution, but the anion slightly reacts with water to form the weak acid. This reaction\n"]], ["block_8", [" 29 . [H2O] > [CH3CO2H] >\n\u2248\n> [OH]\n"]], ["block_9", [" 31 . The oxidation state of the sulfur in H2SO4 is greater than the oxidation state of the sulfur in H2SO3.\n"]], ["block_10", [" 33 .\n"]], ["block_11", [" 35 .\n 37 . The stronger base or stronger acid is the one with the larger Kb or Ka, respectively. In these two examples,\n"]], ["block_12", [" 39 . triethylamine\n 41 . (a)\nhigher electronegativity of the central ion. (b) H2O; NH3 is a base and water is neutral, or\n"]], ["block_13", [" 43 . (a) NaHSeO3 < NaHSO3 < NaHSO4; in polyoxy acids, the more electronegative central element\u2014S, in this\n"]], ["block_14", [" 45 .\n 47 . 1. Assume that the change in initial concentration of the acid as the equilibrium is established can be\n"]], ["block_15", [" 48 . (b) The addition of HCl\n 50 . (a) Adding HCl will add H3Oions, which will then react with the OHions, lowering their concentration.\n"]], ["block_16", [" Access for free at openstax.org \n"]], ["block_17", ["Br; (d)\n(e)\n"]], ["block_18", ["= 14.4\n"]], ["block_19", ["also forms OH, which causes the solution to be basic.\n"]], ["block_20", ["they are (CH3)2NH and\n"]], ["block_21", ["decide on the basis of Ka values. (c) HI; PH3 is weaker than HCl; HCl is weaker than HI. Thus, PH3 is weaker\nthan HI. (d) PH3; in binary compounds of hydrogen with nonmetals, the acidity increases for the element\nlower in a group. (e) HBr; in a period, the acidity increases from left to right; in a group, it increases from\ntop to bottom. Br is to the left and below S, so HBr is the stronger acid.\n"]], ["block_22", ["case\u2014forms the stronger acid. The larger number of oxygen atoms on the central atom (giving it a higher\noxidation state) also creates a greater release of hydrogen atoms, resulting in a stronger acid. As a salt, the\nacidity increases in the same manner. (b)\nthe basicity of the anions in a series\n"]], ["block_23", ["of acids will be the opposite of the acidity in their oxyacids. The acidity increases as the electronegativity\nof the central atom increases. Cl is more electronegative than Br, and I is the least electronegative of the\nthree. (c) HOI < HOBr < HOCl; in a series of the same form of oxyacids, the acidity increases as the\nelectronegativity of the central atom increases. Cl is more electronegative than Br, and I is the least\nelectronegative of the three. (d) HOCl < HOClO < HOClO2 < HOClO3; in a series of oxyacids of the same\ncentral element, the acidity increases as the number of oxygen atoms increases (or as the oxidation state\nof the central atom increases). (e)\nand\nare anions of weak\n"]], ["block_24", ["bases, so they act as strong bases toward H.\nand HSare anions of weak acids, so they have less\n"]], ["block_25", ["basic character. In a periodic group, the more electronegative element has the more basic anion. (f)\n"]], ["block_26", ["of the central ion increases), the corresponding acid becomes more acidic and the anion consequently\nless basic.\n"]], ["block_27", ["neglected, so this concentration can be assumed constant and equal to the initial value of the total acid\nconcentration. 2. Assume we can neglect the contribution of water to the equilibrium concentration of\nH3O.\n"]], ["block_28", ["The equilibrium will shift to the right, increasing the concentration of HNO2, and decreasing the\nconcentration of\nions. (b) Adding HNO2 increases the concentration of HNO2 and shifts the\n"]], ["block_29", ["equilibrium to the left, increasing the concentration of\nions and decreasing the concentration of\n"]], ["block_30", ["OHions. (c) Adding NaOH adds OHions, which shifts the equilibrium to the left, increasing the\nconcentration of\nions and decreasing the concentrations of HNO2. (d) Adding NaCl has no effect on\n"]], ["block_31", ["the concentrations of the ions. (e) Adding KNO2 adds\nions and shifts the equilibrium to the right,\n"]], ["block_32", ["with a larger number of oxygen atoms (that is, as the oxidation state\n"]], ["block_33", ["not amphiprotic: (c)\n"]]], "page_1190": [["block_0", [" 52 . This is a case in which the solution contains a mixture of acids of different ionization strengths. In\n"]], ["block_1", [" 54 . (a)\n(b)\n(c)\n(d)\n"]], ["block_2", [" 56 .\n 58 . (a)\n(b)\n(c)\n(d)\n(e)\n"]], ["block_3", [" 60 . (a)\n"]], ["block_4", [" 62 . pH = 2.41\n 64 . [C10H14N2] = 0.049 M; [C10H14N2H] = 1.9\n10M;\n= 1.4\n10M; [OH] = 1.9\n10\n"]], ["block_5", [" 66 .\n 68 .\n 70 . (a) acidic; (b) basic; (c) acidic; (d) neutral\n 72 . [H3O] and\nare practically equal\n"]], ["block_6", [" 74 . [C6H4(CO2H)2] 7.2\n10M, [C6H4(CO2H)(CO2)] = [H3O] 2.8\n10M,\n3.9\n10M,\n"]], ["block_7", ["M; [H3O] = 5.3\n10M\n"]], ["block_8", ["increasing the HNO2 and OHion concentrations.\n"]], ["block_9", ["solution, the HCO2H exists primarily as HCO2H molecules because the ionization of the weak acid is\nsuppressed by the strong acid. Therefore, the HCO2H contributes a negligible amount of hydronium ions\nto the solution. The stronger acid, HCl, is the dominant producer of hydronium ions because it is\ncompletely ionized. In such a solution, the stronger acid determines the concentration of hydronium ions,\nand the ionization of the weaker acid is fixed by the [H3O] produced by the stronger acid.\n"]], ["block_10", ["(f)\n"]], ["block_11", ["Solving for x gives 1.63\n10M. This value is less than 5% of 0.0092, so the assumption that it can be\n"]], ["block_12", ["neglected is valid. Thus, the concentrations of solute species at equilibrium are:\n[H3O] = [ClO] = 1.6\n10M\n"]], ["block_13", ["[HClO] = 0.0092 M\n[OH] = 6.1\n10M;\n"]], ["block_14", ["(b)\n"]], ["block_15", ["Solving for x gives 5.81\n10M. This value is less than 5% of 0.0784, so the assumption that it can be\n"]], ["block_16", ["neglected is valid. Thus, the concentrations of solute species at equilibrium are:\n"]], ["block_17", ["[C6H5NH2] = 0.0784 M\n[H3O] = 1.7\n10M;\n"]], ["block_18", ["(c)\n"]], ["block_19", ["Solving for x gives 6.30\n10M. This value is less than 5% of 0.0810, so the assumption that it can be\n"]], ["block_20", ["neglected is valid. Thus, the concentrations of solute species at equilibrium are:\n[H3O] = [CN] = 6.3\n10M\n"]], ["block_21", ["[HCN] = 0.0810 M\n[OH] = 1.6\n10M;\n"]], ["block_22", ["(d)\n"]], ["block_23", ["Solving for x gives 2.63\n10M. This value is less than 5% of 0.11, so the assumption that it can be\n"]], ["block_24", ["neglected is valid. Thus, the concentrations of solute species at equilibrium are:\n[(CH3)3NH] = [OH] = 2.6\n10M\n"]], ["block_25", ["[(CH3)3N] = 0.11 M\n[H3O] = 3.8\n10M;\n"]], ["block_26", ["(e)\n"]], ["block_27", ["Solving for x gives 1.39\n10M. This value is less than 5% of 0.120, so the assumption that it can be\n"]], ["block_28", ["neglected is valid. Thus, the concentrations of solute species at equilibrium are:\n[Fe(H2O)5(OH)] = [H3O] = 1.4\n10M\n"]], ["block_29", ["[OH] = 7.2\n10M\n"]], ["block_30", ["= [OH] = 5.8\n10M\n"]], ["block_31", ["= 0.120 M\n"]], ["block_32", [" 1177 \n"]]], "page_1191": [["block_0", [" 1178 \n"]], ["block_1", [" 76 . (a)\n"]], ["block_2", [" 78 . Excess H3Ois removed primarily by the reaction:\n"]], ["block_3", [" 80 . [H3O] = 1.5\n10M\n"]], ["block_4", [" 82 . [OH] = 4.2\n10M\n"]], ["block_5", [" 84 . (a) The added HCl will increase the concentration of H3Oslightly, which will react with\nand\n"]], ["block_6", [" 86 . pH = 8.95\n 88 . 37 g (0.27 mol)\n 90 . (a) pH = 5.222; (b) The solution is acidic. (c) pH = 5.220\n 92 . At the equivalence point in the titration of a weak base with a strong acid, the resulting solution is slightly\n"]], ["block_7", [" 94 . (a) pH = 2.50; (b) pH = 4.01; (c) pH = 5.60; (d) pH = 8.35; (e) pH = 11.08\n"]], ["block_8", [" Chapter 15 \n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", [" 1 . (a)\n"]], ["block_11", [" 3 . There is no change. A solid has an activity of 1 whether there is a little or a lot.\n 5 . The solubility of silver bromide at the new temperature must be known. Normally the solubility increases\n"]], ["block_12", ["(b)\n"]], ["block_13", ["(c)\n"]], ["block_14", ["(d)\n"]], ["block_15", ["(e)\n"]], ["block_16", ["and some of the solid silver bromide will dissolve.\n"]], ["block_17", ["[OH] 3.6\n10M\n"]], ["block_18", ["(b)\n"]], ["block_19", ["(c)\n"]], ["block_20", ["Solving for x gives 1.5\n10M. Therefore, compared with 0.014 M, this value is negligible (1.1\n"]], ["block_21", ["10%).\n"]], ["block_22", ["Excess base is removed by the reaction:\n"]], ["block_23", ["produce CH3CO2H in the process. Thus,\ndecreases and [CH3CO2H] increases. (b) The added\n"]], ["block_24", ["KCH3CO2 will increase the concentration of\nwhich will react with H3Oand produce CH3CO2\n"]], ["block_25", ["H in the process. Thus, [H3O] decreases slightly and [CH3CO2H] increases. (c) The added NaCl will have no\neffect on the concentration of the ions. (d) The added KOH will produce OHions, which will react with the\nH3O, thus reducing [H3O]. Some additional CH3CO2H will dissociate, producing\nions in the\n"]], ["block_26", ["process. Thus, [CH3CO2H] decreases slightly and\nincreases. (e) The added CH3CO2H will\n"]], ["block_27", ["increase its concentration, causing more of it to dissociate and producing more\nand H3Oin\n"]], ["block_28", ["the process. Thus, [H3O] increases slightly and\nincreases.\n"]], ["block_29", ["acidic due to the presence of the conjugate acid. Thus, pick an indicator that changes color in the acidic\nrange and brackets the pH at the equivalence point. Methyl orange is a good example.\n"]]], "page_1192": [["block_0", [" 11 . (a)1.77\n10; (b) 1.6\n10; (c) 2.2\n10; (d) 7.91\n10\n"]], ["block_1", [" 13 . (a) 2\n10M; (b) 1.5\n10M; (c) 2.27\n10M; (d) 2.2\n10M\n"]], ["block_2", [" 15 . (a) 6.4\n10M = [Ag], [Cl] = 0.025 M. Check:\nan insignificant\n"]], ["block_3", [" 17 . (a) [Cl] = 7.6\n10M\n"]], ["block_4", [" 19 . The changes in concentration are greater than 5% and thus exceed the maximum value for disregarding\n"]], ["block_5", [" 21 . CaSO4\u22192H2O is the most soluble Ca salt in mol/L, and it is also the most soluble Ca salt in g/L.\n 23 . 4.8\n10M =\n= [Ca]; Since this concentration is higher than 2.60\n10M, \u201cgyp\u201d water does\n"]], ["block_6", [" 25 . Mass (CaSO4\u00b72H2O) = 0.72 g/L\n 27 . (a) [Ag] = [I] = 1.3\n10M; (b) [Ag] = 2.88\n10M,\n= 1.44\n10M; (c) [Mn] = 3.7\n10M,\n"]], ["block_7", [" 29 . (a) 1.45\n10; (b) 8.2\n10; (c) 1.35\n10; (d) 1.18\n10; (e) 1.08\n10\n"]], ["block_8", [" 31 . (a) CaCO3 does precipitate. (b) The compound does not precipitate. (c) The compound does not precipitate.\n"]], ["block_9", [" 7 . CaF2, MnCO3, and ZnS\n 9 . (a)\n"]], ["block_10", ["(b)\n"]], ["block_11", ["(c)\n"]], ["block_12", ["(d)\n"]], ["block_13", ["change;\n"]], ["block_14", ["(b) 2.2\n10M = [Ca], [F] = 0.0013 M. Check:\nThis value is less than\n"]], ["block_15", ["5% and can be ignored.\n"]], ["block_16", ["(c) 0.2238 M =\n[Ag] = 7.4\n10M. Check:\nthe condition is\n"]], ["block_17", ["satisfied.\n"]], ["block_18", ["(d) [OH] = 2.8\n10M; 5.7\n10M = [Zn]. Check:\nx is less than\n"]], ["block_19", ["5% of [OH] and is, therefore, negligible.\n"]], ["block_20", ["Check:\n"]], ["block_21", ["This value is too large to drop x. Therefore solve by using the quadratic equation:\n[Ti] = 3.1\n10M\n"]], ["block_22", ["[Cl] = 6.1\n10\n"]], ["block_23", ["(b) [Ba] = 7.7\n10M\n"]], ["block_24", ["Check:\n"]], ["block_25", ["Therefore, the condition is satisfied.\n[Ba] = 7.7\n10M\n"]], ["block_26", ["[F] = 0.0321 M;\n(c) Mg(NO3)2 = 0.02444 M\n"]], ["block_27", ["Check:\n"]], ["block_28", ["The condition is satisfied; the above value is less than 5%.\n"]], ["block_29", ["[Mg] = 0.0244 M\n(d) [OH] = 0.0501 M\n[Ca] = 3.15\n10\n"]], ["block_30", ["Check:\n"]], ["block_31", ["This value is greater than 5%, so a more exact method, such as successive approximations, must be used.\n[Ca] = 2.8\n10M\n"]], ["block_32", ["[OH] = 0.053\n10M\n"]], ["block_33", ["the change.\n"]], ["block_34", ["not meet the standards.\n"]], ["block_35", ["[OH] = 7.4\n10M; (d) [Sr] = 4.3\n10M, [OH] = 8.6\n10M; (e) [Mg] = 1.3\n10M, [OH] = 2.6\n"]], ["block_36", ["10M.\n"]], ["block_37", [" 1179 \n"]]], "page_1193": [["block_0", [" 1180 \n"]], ["block_1", [" 33 . 3.03\n10M\n"]], ["block_2", [" 35 . 9.2\n10M\n"]], ["block_3", [" 37 . [Ag] = 1.8\n10M\n"]], ["block_4", [" 39 . 6.3\n10\n"]], ["block_5", [" 41 . (a) 2.25 L; (b) 7.2\n10g\n"]], ["block_6", [" 43 . 100% of it is dissolved\n 45 . (a)\nand Cu: Add\n(b)\nand Cl: Add Ba. (c) Hgand Co: Add S. (d) Znand\n"]], ["block_7", [" 47 . AgI will precipitate first.\n 49 . 1.5\n10M\n"]], ["block_8", [" 51 . 3.99 kg\n 53 . (a) 3.1\n10; (b) [Cu] = 2.6\n10;\n= 5.3\n10\n"]], ["block_9", [" 55 . 1.8\n10g Pb(OH)2\n"]], ["block_10", [" 57 .\n"]], ["block_11", [" 59 . MnCO3 will form first since it has the smallest Ksp value among these homologous compounds and is\n"]], ["block_12", [" 62 . when the amount of solid is so small that a saturated solution is not produced\n 64 . 1.8\n10M\n"]], ["block_13", [" 66 . 5\n10\n"]], ["block_14", [" 68 .\n"]], ["block_15", [" 70 . [Co] = 3.0\n10M; [NH3] = 1.8\n10M\n"]], ["block_16", [" 72 . 1.3 g\n 74 . 0.79 g\n 76 . (a)\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", ["(d) The compound precipitates.\n"]], ["block_19", ["Sr: Add OHuntil [OH] = 0.050 M. (e) Baand Mg: Add\n(f)\nand OH: Add Ba.\n"]], ["block_20", ["1.23\n10g Mg(OH)2\n"]], ["block_21", ["therefore the least soluble. MgCO3\u20223H2O will be the last to precipitate since it has the largest K_sp value\nand is the most soluble. Ksp value.\n"]], ["block_22", [{"image_0": "1193_0.png", "coords": [91, 345, 442, 419]}]], ["block_23", ["[Cd] = 9.5\n10M; [CN] = 3.8\n10M\n"]], ["block_24", [{"image_1": "1193_1.png", "coords": [91, 498, 325, 552]}]], ["block_25", ["(b)\n"]], ["block_26", [{"image_2": "1193_2.png", "coords": [91, 580, 442, 653]}]], ["block_27", ["(c)\n"]], ["block_28", [{"image_3": "1193_3.png", "coords": [91, 681, 325, 722]}]]], "page_1194": [["block_0", [" 78 . (a)\n"]], ["block_1", [" 80 . 0.0281 g\n 82 .\n 84 . (a)\n(b) The electronic and molecular shapes are the same\u2014both\n"]], ["block_2", [" 86 . 0.014 M\n 88 . 7.2\n10M\n"]], ["block_3", ["(d)\n"]], ["block_4", [{"image_0": "1194_0.png", "coords": [91, 82, 325, 158]}]], ["block_5", ["(e)\n"]], ["block_6", [{"image_1": "1194_1.png", "coords": [91, 186, 325, 260]}]], ["block_7", [{"image_2": "1194_2.png", "coords": [91, 276, 442, 385]}]], ["block_8", ["(b)\n"]], ["block_9", [{"image_3": "1194_3.png", "coords": [91, 413, 523, 469]}]], ["block_10", ["(c)\n"]], ["block_11", [{"image_4": "1194_4.png", "coords": [91, 498, 442, 559]}]], ["block_12", ["(d)\n"]], ["block_13", [{"image_5": "1194_5.png", "coords": [91, 588, 523, 651]}]], ["block_14", ["tetrahedral. (c) The tetrahedral structure is consistent with sphybridization.\n"]], ["block_15", [" 1181 \n"]]], "page_1195": [["block_0", [" 1182 \n"]], ["block_1", [" 90 . 4.4\n10M\n"]], ["block_2", [" 93 . [OH] = 4.5\n10; [Al] = 2\n10(molar solubility)\n"]], ["block_3", [" 95 .\n; [Ba] = 4.7\n10(molar solubility)\n"]], ["block_4", [" 97 . [OH] = 7.6\n10M; [Pb] = 2.1\n10(molar solubility)\n"]], ["block_5", [" 99 . 7.66\n 101 . (a) Ksp = [Mg][F]= (1.21\n10)(2\n1.21\n10)= 7.09\n10\n"]], ["block_6", [" 103 . BaF2, Ca3(PO4)2, ZnS; each is a salt of a weak acid, and the\nfrom perchloric acid reduces the\n"]], ["block_7", [" 105 . Effect on amount of solid CaHPO4, [Ca], [OH]: (a) increase, increase, decrease; (b) decrease, increase,\n"]], ["block_8", [" Chapter 16 \n"]], ["block_9", [" 11 . There is only one initial state. For the final state, the energy can be contained in pairs A-C, A-D, B-C, or B-D.\n"]], ["block_10", [" 13 . The masses of these molecules would suggest the opposite trend in their entropies. The observed trend is\n"]], ["block_11", [" 15 . (a) C3H7OH(l) as it is a larger molecule (more complex and more massive), and so more microstates\n"]], ["block_12", [" 17 . (a) Negative. The relatively ordered solid precipitating decreases the number of mobile ions in solution.\n"]], ["block_13", [" Access for free at openstax.org \n"]], ["block_14", [" 1 . A reaction has a natural tendency to occur and takes place without the continual input of energy from an\n"]], ["block_15", [" 3 . (a) spontaneous; (b) nonspontaneous; (c) spontaneous; (d) nonspontaneous; (e) spontaneous; (f)\n"]], ["block_16", [" 5 . Although the oxidation of plastics is spontaneous, the rate of oxidation is very slow. Plastics are therefore\n"]], ["block_17", [" 7 . There are four initial microstates and four final microstates.\n"]], ["block_18", [" 9 . The probability for all the particles to be on one side is\nThis probability is noticeably lower than the\n"]], ["block_19", ["external source.\n"]], ["block_20", ["spontaneous\n"]], ["block_21", ["kinetically stable and do not decompose appreciably even over relatively long periods of time.\n"]], ["block_22", ["result for the four-particle system. The conclusion we can make is that the probability for all the particles\nto stay in only one part of the system will decrease rapidly as the number of particles increases, and, for\ninstance, the probability for all molecules of gas to gather in only one side of a room at room temperature\nand pressure is negligible since the number of gas molecules in the room is very large.\n"]], ["block_23", ["Thus, there are four final possible states.\n"]], ["block_24", ["a result of the more significant variation of entropy with a physical state. At room temperature, I2 is a\nsolid, Br2 is a liquid, and Cl2 is a gas.\n"]], ["block_25", ["describing its motions are available at any given temperature. (b) C2H5OH(g) as it is in the gaseous state.\n(c) 2H(g), since entropy is an extensive property, and so two H atoms (or two moles of H atoms) possess\ntwice as much entropy as one atom (or one mole of atoms).\n"]], ["block_26", ["(b) Negative. There is a net loss of three moles of gas from reactants to products. (c) Positive. There is a net\n"]], ["block_27", ["M Mg(NO3)2 = 1.00\n10M\n"]], ["block_28", ["M NaF = 1.33\n10M\n"]], ["block_29", ["(b) 7.09\n10M\n"]], ["block_30", ["(c) Determine the concentration of Mgand Fthat will be present in the final volume. Compare the\nvalue of the ion product [Mg][F]with Ksp. If this value is larger than Ksp, precipitation will occur.\n0.1000 L\n3.00\n10M Mg(NO3)2 = 0.3000 L\nM Mg(NO3)2\n"]], ["block_31", ["0.2000 L\n2.00\n10M NaF = 0.3000 L\nM NaF\n"]], ["block_32", ["ion product = (1.00\n10)(1.33\n10)= 1.77\n10This value is smaller than Ksp, so no precipitation\n"]], ["block_33", ["will occur.\n(d) MgF2 is less soluble at 27 \u00b0C than at 18 \u00b0C. Because added heat acts like an added reagent, when it\nappears on the product side, the Le Ch\u00e2telier\u2019s principle states that the equilibrium will shift to the\nreactants\u2019 side to counter the stress. Consequently, less reagent will dissolve. This situation is found in\nour case. Therefore, the reaction is exothermic.\n"]], ["block_34", ["equilibrium concentration of the anion, thereby increasing the concentration of the cations\n"]], ["block_35", ["decrease; (c) no effect, no effect, no effect; (d) decrease, increase, decrease; (e) increase, no effect, no\neffect\n"]]], "page_1196": [["block_0", [" 19 .\n"]], ["block_1", [" 21 . (a) 107 J/K; (b) \u221286.4 J/K; (c) 133.2 J/K; (d) 118.8 J/K; (e) \u2212326.6 J/K; (f) \u2212171.9 J/K; (g) \u22127.2 J/K\n 23 . 100.6 J/K\n 25 . (a) \u2212198.1 J/K; (b) \u2212348.9 J/K\n 27 . As \u0394Suniv < 0 at each of these temperatures, melting is not spontaneous at either of them. The given values\n"]], ["block_2", [" 29 . (a) 2.86 J/K; (b) 24.8 J/K; (c) \u2212113.2 J/K; (d) \u221224.7 J/K; (e) 15.5 J/K; (f) 290.0 J/K\n 31 . The reaction is nonspontaneous at room temperature.\n"]], ["block_3", [" 33 . (a) 465.1 kJ nonspontaneous; (b) \u2212106.86 kJ spontaneous; (c) \u2212291.9 kJ spontaneous; (d) \u221283.4 kJ\n"]], ["block_4", [" 35 . (a) The standard free energy of formation is \u20131124.3 kJ/mol. (b) The calculation agrees with the value in\n"]], ["block_5", [" 37 . (a) The reaction is nonspontaneous; (b) Above 566 \u00b0C the process is spontaneous.\n 39 . (a) 1.5\n10kJ; (b) \u221221.9 kJ; (c) \u22125.34 kJ; (d) \u22120.383 kJ; (e) 18 kJ; (f) 71 kJ\n"]], ["block_6", [" 41 . (a) K = 41; (b) K = 0.053; (c) K = 6.9\n10; (d) K = 1.9; (e) K = 0.04\n"]], ["block_7", [" 43 . In each of the following, the value of \u0394G is not given at the temperature of the reaction. Therefore, we must\n"]], ["block_8", [" 45 . The standard free energy change is\nWhen reactants and products are in\n"]], ["block_9", [" 47 . The reaction will be spontaneous at temperatures greater than 287 K.\n 49 . K = 5.35\n10; The process is exothermic.\n"]], ["block_10", [" 51 . 1.0\n10atm. This is the maximum pressure of the gases under the stated conditions.\n"]], ["block_11", [" 53 .\n"]], ["block_12", [" 55 . \u22120.16 kJ\n 56 . (a) 22.1 kJ; (b) 98.9 kJ/mol\n 58 . 90 kJ/mol\n 60 . (a) Under standard thermodynamic conditions, the evaporation is nonspontaneous; (b) Kp = 0.031; (c) The\n"]], ["block_13", [" 62 . (a) Nonspontaneous as\n(b)\n"]], ["block_14", [" 64 . \u0394G is negative as the process is spontaneous. \u0394H is positive as with the solution becoming cold, the\n"]], ["block_15", [" 66 . (a) Increasing the oxygen partial pressure will yield a decrease in Q and\nthus becomes more negative.\n"]], ["block_16", [" Chapter 17 \n"]], ["block_17", [" 1 . (a) reduction; (b) oxidation; (c) oxidation; (d) reduction\n 3 . (a)\n(b)\n(c)\n(d)\n"]], ["block_18", ["increase of seven moles of gas from reactants to products.\n"]], ["block_19", ["There are 7.5 moles of gas initially, and 3 + 6 = 9 moles of gas in the end. Therefore, it is likely that the\nentropy increases as a result of this reaction, and \u0394S is positive.\n"]], ["block_20", ["for entropy and enthalpy are for NaCl at 298 K. It is assumed that these do not change significantly at the\nhigher temperatures used in the problem.\n"]], ["block_21", ["Above 400 K, \u0394G will become negative, and the reaction will become spontaneous.\n"]], ["block_22", ["spontaneous; (e) \u2212406.7 kJ spontaneous; (f) \u2212154.3 kJ spontaneous\n"]], ["block_23", ["Appendix G because free energy is a state function (just like the enthalpy and entropy), so its change\ndepends only on the initial and final states, not the path between them.\n"]], ["block_24", ["calculate \u0394G from the values \u0394H\u00b0 and \u0394S and then calculate \u0394G from the relation \u0394G = \u0394H\u00b0 \u2212 T\u0394S\u00b0. (a) K =\n1.07 \u00d7 10; (b) K = 2.51\n10; (c) K = 4.83\n10; (d) K = 0.219; (e) K = 16.1\n"]], ["block_25", ["their standard states (1 bar or 1 atm), Q = 1. As the reaction proceeds toward equilibrium, the reaction\nshifts left (the amount of products drops while the amount of reactants increases): Q < 1, and\nbecomes\n"]], ["block_26", ["less positive as it approaches zero. At equilibrium, Q = K, and \u0394G = 0.\n"]], ["block_27", ["evaporation of water is spontaneous; (d)\nmust always be less than Kp or less than 0.031 atm. 0.031\n"]], ["block_28", ["atm represents air saturated with water vapor at 25 \u00b0C, or 100% humidity.\n"]], ["block_29", ["spontaneous under these conditions.\n"]], ["block_30", ["dissolving must be endothermic. \u0394S must be positive as this drives the process, and it is expected for the\ndissolution of any soluble ionic compound.\n"]], ["block_31", ["(b) Increasing the oxygen partial pressure will yield a decrease in Q and\nthus becomes more negative.\n"]], ["block_32", ["(c) Increasing the oxygen partial pressure will yield an increase in Q and\nthus becomes more positive.\n"]], ["block_33", ["The forward reaction to produce F6P is\n"]], ["block_34", [" 1183 \n"]]], "page_1197": [["block_0", [" 1184 \n"]], ["block_1", [" 11 . (a)\n(b)\n(c)\n"]], ["block_2", [" 13 . (a)\n(b)\n"]], ["block_3", [" 15 . Species oxidized = reducing agent: (a) Al(s); (b) NO(g); (c) Mg(s); and (d) MnO2(s); Species reduced =\n"]], ["block_4", [" 17 . Without the salt bridge, the circuit would be open (or broken) and no current could flow. With a salt bridge,\n"]], ["block_5", [" 19 . Active electrodes participate in the oxidation-reduction reaction. Since metals form cations, the electrode\n"]], ["block_6", [" 21 . (a) +2.115 V (spontaneous); (b) +0.4626 V (spontaneous); (c) +1.0589 V (spontaneous); (d) +0.727 V\n"]], ["block_7", [" 23 .\n+1.16 V; spontaneous\n"]], ["block_8", [" 25 .\n\u22121.259 V; nonspontaneous\n"]], ["block_9", [" 27 . (a) 0 kJ/mol; (b) \u221283.7 kJ/mol; (c) +235.3 kJ/mol\n 29 . (a) standard cell potential: 1.50 V, spontaneous; cell potential under stated conditions: 1.43 V,\n"]], ["block_10", [" 31 . (a) 1.7\n10; (b) 2.6\n10; (c) 4.693\n10; (d) 1.0\n10\n"]], ["block_11", [" 33 . (a)\n(b) 3.5\n10; (c) 5.6\n10\n"]], ["block_12", [" 34 . Batteries are self-contained and have a limited supply of reagents to expend before going dead.\n"]], ["block_13", [" 36 . Ecell, as described in the Nernst equation, has a term that is directly proportional to temperature. At low\n"]], ["block_14", [" 38 . Mg and Zn\n 40 . Both examples involve cathodic protection. The (sacrificial) anode is the metal that corrodes (oxidizes or\n"]], ["block_15", [" 42 . While the reduction potential of lithium would make it capable of protecting the other metals, this high\n"]], ["block_16", [" 46 . (a)\n(b)\n(c)\n(d)\n"]], ["block_17", [" Access for free at openstax.org \n"]], ["block_18", [" 5 . Oxidized: (a) Sn; (b) Hg; (c) Al; reduced: (a) H2O2; (b) PbO2; (c)\noxidizing agent: (a) H2O2; (b)\n"]], ["block_19", [" 7 . Oxidized = reducing agent: (a)\n(b) Mn(OH)2; (c) H2; (d) Al; reduced = oxidizing agent: (a) Cu(OH)2;\n"]], ["block_20", [" 9 . In basic solution, [OH] > 1\n10M > [H]. Hydrogen ion cannot appear as a reactant because its\n"]], ["block_21", ["PbO2; (c)\nreducing agent: (a) Sn; (b) Hg; (c) Al\n"]], ["block_22", ["(b) O2; (c)\n(d)\n"]], ["block_23", ["concentration is essentially zero. If it were produced, it would instantly react with the excess hydroxide ion\nto produce water. Thus, hydrogen ion should not appear as a reactant or product in basic solution.\n"]], ["block_24", ["M\n"]], ["block_25", ["oxidizing agent: (a) Zr(aq); (b) Ag(aq); (c)\n; and (d)\n"]], ["block_26", ["each half-cell remains electrically neutral and current can flow through the circuit.\n"]], ["block_27", ["would lose mass if metal atoms in the electrode were to oxidize and go into solution. Oxidation occurs at\nthe anode.\n"]], ["block_28", ["(spontaneous)\n"]], ["block_29", ["spontaneous; (b) standard cell potential: 1.405 V, spontaneous; cell potential under stated conditions:\n1.423 V, spontaneous; (c) standard cell potential: \u22122.749 V, nonspontaneous; cell potential under stated\nconditions: \u22122.757 V, nonspontaneous\n"]], ["block_30", ["Alternatively, battery reaction byproducts accumulate and interfere with the reaction. Because a fuel cell\nis constantly resupplied with reactants and products are expelled, it can continue to function as long as\nreagents are supplied.\n"]], ["block_31", ["temperatures, this term is decreased, resulting in a lower cell voltage provided by the battery to the\ndevice\u2014the same effect as a battery running dead.\n"]], ["block_32", ["reacts). In the case of iron (\u22120.447 V) and zinc (\u22120.7618 V), zinc has a more negative standard reduction\npotential and so serves as the anode. In the case of iron and copper (0.34 V), iron has the smaller standard\nreduction potential and so corrodes (serves as the anode).\n"]], ["block_33", ["potential is also indicative of how reactive lithium is; it would have a spontaneous reaction with most\nsubstances. This means that the lithium would react quickly with other substances, even those that would\nnot oxidize the metal it is attempting to protect. Reactivity like this means the sacrificial anode would be\ndepleted rapidly and need to be replaced frequently. (Optional additional reason: fire hazard in the\npresence of water.)\n"]], ["block_34", ["(d)\n"]]], "page_1198": [["block_0", [" 48 . 0.79 L\n"]], ["block_1", [" Chapter 18 \n"]], ["block_2", [" 9 . 11 lb\n 11 . Yes, tin reacts with hydrochloric acid to produce hydrogen gas.\n 13 . In PbCl2, the bonding is ionic, as indicated by its melting point of 501 \u00b0C. In PbCl4, the bonding is covalent,\n"]], ["block_3", [" 15 .\n"]], ["block_4", [" 17 . Cathode (reduction):\nAnode (oxidation):\nOverall\n"]], ["block_5", [" 19 . 0.5035 g H2\n 21 . Despite its reactivity, magnesium can be used in construction even when the magnesium is going to come\n"]], ["block_6", [" 23 . Extract from ore:\n"]], ["block_7", [" 25 . 25.83%\n 27 . 39 kg\n 29 . (a) H3BPH3:\n"]], ["block_8", [" 1 . The alkali metals all have a single s electron in their outermost shell. In contrast, the alkaline earth metals\n"]], ["block_9", [" 3 .\n"]], ["block_10", [" 5 . The possible ways of distinguishing between the two include infrared spectroscopy by comparison of\n"]], ["block_11", [" 7 . (a)\n(b)\n(c)\n"]], ["block_12", ["have a completed s subshell in their outermost shell. In general, the alkali metals react faster and are more\nreactive than the corresponding alkaline earth metals in the same period.\n"]], ["block_13", ["known compounds, a flame test that gives the characteristic yellow color for sodium (strontium has a red\n"]], ["block_14", ["flame), or comparison of their solubilities in water. At 20 \u00b0C, NaCl dissolves to the extent of\n"]], ["block_15", ["compared with\nfor SrCl2. Heating to 100 \u00b0C provides an easy test, since the solubility of NaCl is\n"]], ["block_16", ["enough difference (2.165 g/mL NaCl and 3.052 g/mL SrCl2) that this method would be viable and perhaps\nthe easiest and least expensive test to perform.\n"]], ["block_17", ["as evidenced by it being an unstable liquid at room temperature.\n"]], ["block_18", ["reaction:\n"]], ["block_19", ["in contact with a flame because a protective oxide coating is formed, preventing gross oxidation. Only if\nthe metal is finely subdivided or present in a thin sheet will a high-intensity flame cause its rapid burning.\n"]], ["block_20", ["Recover:\n"]], ["block_21", ["Sinter:\nDissolve in Na3AlF6(l) and electrolyze:\n"]], ["block_22", ["but that of SrCl2 is\nDensity determination on a solid is sometimes difficult, but there is\n"]], ["block_23", ["(d)\n(e)\n"]], ["block_24", [" 1185 \n"]]], "page_1199": [["block_0", [" 1186 \n"]], ["block_1", [" 31 . 1s2s2p3s3p3d.\n 33 . (a) (CH3)3SiH: spbonding about Si; the structure is tetrahedral; (b)\nspbonding about Si; the\n"]], ["block_2", [" 35 . (a) nonpolar; (b) nonpolar; (c) polar; (d) nonpolar; (e) polar\n 37 . (a) tellurium dioxide or tellurium(IV) oxide; (b) antimony(III) sulfide; (c) germanium(IV) fluoride; (d) silane\n"]], ["block_3", [" 39 . Boron has only s and p orbitals available, which can accommodate a maximum of four electron pairs.\n"]], ["block_4", [" 41 . (a) \u0394H\u00b0 = 87 kJ; \u0394G\u00b0 = 44 kJ; (b) \u0394H\u00b0 = \u2212109.9 kJ; \u0394G\u00b0 = \u2212154.7 kJ; (c) \u0394H\u00b0 = \u2212510 kJ; \u0394G\u00b0 = \u2212601.5 kJ\n 43 . A mild solution of hydrofluoric acid would dissolve the silicate and would not harm the diamond.\n 45 . In the N2 molecule, the nitrogen atoms have an \u03c3 bond and two \u03c0 bonds holding the two atoms together.\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", [{"image_0": "1199_0.png", "coords": [91, 57, 162, 109]}]], ["block_7", ["(b)\n"]], ["block_8", [{"image_1": "1199_1.png", "coords": [91, 137, 167, 195]}]], ["block_9", ["(c) BBr3:\n"]], ["block_10", [{"image_2": "1199_2.png", "coords": [91, 223, 134, 284]}]], ["block_11", ["(d) B(CH3)3:\n"]], ["block_12", [{"image_3": "1199_3.png", "coords": [91, 312, 182, 404]}]], ["block_13", ["(e) B(OH)3:\n"]], ["block_14", [{"image_4": "1199_4.png", "coords": [91, 432, 147, 525]}]], ["block_15", ["structure is tetrahedral; (c) Si2H6: spbonding about each Si; the structure is linear along the Si-Si bond;\n(d) Si(OH)4: spbonding about Si; the structure is tetrahedral; (e)\nspdbonding about Si; the\n"]], ["block_16", ["structure is octahedral\n"]], ["block_17", ["or silicon(IV) hydride; (e) germanium(IV) hydride\n"]], ["block_18", ["Unlike silicon, no d orbitals are available in boron.\n"]], ["block_19", ["The presence of three strong bonds makes N2 a very stable molecule. Phosphorus is a third-period\nelement, and as such, does not form \u03c0 bonds efficiently; therefore, it must fulfill its bonding requirement\nby forming three \u03c3 bonds.\n"]]], "page_1200": [["block_0", [" 47 . (a) H = 1+, C = 2+, and N = 3\u2212; (b) O = 2+ and F = 1\u2212; (c) As = 3+ and Cl = 1\u2212\n 49 . S < Cl < O < F\n 51 . The electronegativity of the nonmetals is greater than that of hydrogen. Thus, the negative charge is better\n"]], ["block_1", [" 53 . Hydrogen has only one orbital with which to bond to other atoms. Consequently, only one two-electron\n"]], ["block_2", [" 55 . 0.43 g H2\n 57 . (a)\n(b)\n"]], ["block_3", [" 59 . (a) NH:\n"]], ["block_4", [" 61 . Ammonia acts as a Br\u00f8nsted base because it readily accepts protons and as a Lewis base in that it has an\n"]], ["block_5", [" 63 . (a) NO2:\n"]], ["block_6", ["represented on the nonmetal, which has the greater tendency to attract electrons in the bond to itself.\n"]], ["block_7", ["bond can form.\n"]], ["block_8", ["(c)\n"]], ["block_9", [{"image_0": "1200_0.png", "coords": [91, 183, 208, 210]}]], ["block_10", ["(b) N2F4:\n"]], ["block_11", [{"image_1": "1200_1.png", "coords": [91, 238, 208, 294]}]], ["block_12", ["(c)\n"]], ["block_13", [{"image_2": "1200_2.png", "coords": [91, 323, 208, 364]}]], ["block_14", ["(d) NF3:\n"]], ["block_15", [{"image_3": "1200_3.png", "coords": [91, 392, 208, 434]}]], ["block_16", ["(e)\n"]], ["block_17", [{"image_4": "1200_4.png", "coords": [91, 462, 451, 492]}]], ["block_18", ["electron pair to donate.\nBr\u00f8nsted base:\nLewis base:\n"]], ["block_19", [{"image_5": "1200_5.png", "coords": [91, 558, 325, 596]}]], ["block_20", ["Nitrogen is sphybridized. The molecule has a bent geometry with an ONO bond angle of approximately\n120\u00b0.\n(b)\n"]], ["block_21", [{"image_6": "1200_6.png", "coords": [91, 650, 325, 694]}]], ["block_22", ["Nitrogen is sphybridized. The molecule has a bent geometry with an ONO bond angle slightly less than\n"]], ["block_23", [" 1187 \n"]]], "page_1201": [["block_0", [" 1188 \n"]], ["block_1", [" 65 . Nitrogen cannot form a NF5 molecule because it does not have d orbitals to bond with the additional two\n"]], ["block_2", [" 67 . (a)\n"]], ["block_3", [" 69 . (a)\n(b)\n(c)\n(d)\n"]], ["block_4", [" 71 . 291 mL\n 73 . 28 tons\n 75 . (a)\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", ["120\u00b0.\n(c)\n"]], ["block_7", [{"image_0": "1201_0.png", "coords": [91, 82, 208, 110]}]], ["block_8", ["Nitrogen is sp hybridized. The molecule has a linear geometry with an ONO bond angle of 180\u00b0.\n"]], ["block_9", ["fluorine atoms.\n"]], ["block_10", [{"image_1": "1201_1.png", "coords": [91, 176, 208, 207]}]], ["block_11", ["(b)\n"]], ["block_12", [{"image_2": "1201_2.png", "coords": [91, 235, 208, 279]}]], ["block_13", ["(c)\n"]], ["block_14", [{"image_3": "1201_3.png", "coords": [91, 307, 208, 344]}]], ["block_15", ["(d)\n"]], ["block_16", [{"image_4": "1201_4.png", "coords": [91, 372, 208, 421]}]], ["block_17", ["(e)\n"]], ["block_18", [{"image_5": "1201_5.png", "coords": [91, 449, 208, 510]}]], ["block_19", [{"image_6": "1201_6.png", "coords": [91, 589, 208, 656]}]], ["block_20", ["(b)\n"]], ["block_21", ["or\n(e)\nor\n"]], ["block_22", ["(f)\n"]]], "page_1202": [["block_0", [" 77 . (a) P = 3+; (b) P = 5+; (c) P = 3+; (d) P = 5+; (e) P = 3\u2212; (f) P = 5+\n 79 . FrO2\n 81 . (a)\n(b)\n(c)\n"]], ["block_1", [" 83 .\n"]], ["block_2", [" 85 . (a)\n(b)\n"]], ["block_3", [" 87 . HClO4 is the stronger acid because, in a series of oxyacids with similar formulas, the higher the\n"]], ["block_4", [" 89 . As H2SO4 and H2SeO4 are both oxyacids and their central atoms both have the same oxidation number, the\n"]], ["block_5", [" 91 . SO2, sp4+; SO3, sp, 6+; H2SO4, sp, 6+\n 93 . SF6: S = 6+; SO2F2: S = 6+; KHS: S = 2\u2212\n 95 . Sulfur is able to form double bonds only at high temperatures (substantially endothermic conditions),\n"]], ["block_6", [" 97 . There are many possible answers including:\n"]], ["block_7", [" 99 . 5.1\n10g\n"]], ["block_8", [" 101 . SnCl4 is not a salt because it is covalently bonded. A salt must have ionic bonds.\n 103 . In oxyacids with similar formulas, the acid strength increases as the electronegativity of the central atom\n"]], ["block_9", [" 105 . (a)\n"]], ["block_10", [{"image_0": "1202_0.png", "coords": [91, 57, 208, 136]}]], ["block_11", ["(c)\n"]], ["block_12", [{"image_1": "1202_1.png", "coords": [91, 164, 208, 245]}]], ["block_13", ["(d)\n"]], ["block_14", [{"image_2": "1202_2.png", "coords": [91, 273, 208, 340]}]], ["block_15", ["(c)\n(d)\n"]], ["block_16", ["electronegativity of the central atom, the stronger is the attraction of the central atom for the electrons of\nthe oxygen(s). The stronger attraction of the oxygen electron results in a stronger attraction of oxygen for\nthe electrons in the O-H bond, making the hydrogen more easily released. The weaker this bond, the\nstronger the acid.\n"]], ["block_17", ["acid strength depends on the relative electronegativity of the central atom. As sulfur is more\nelectronegative than selenium, H2SO4 is the stronger acid.\n"]], ["block_18", ["which is not the case for oxygen.\n"]], ["block_19", ["and\n"]], ["block_20", ["increases. HClO3 is stronger than HBrO3; Cl is more electronegative than Br.\n"]], ["block_21", ["(e)\n"]], ["block_22", ["(d)\n"]], ["block_23", [" 1189 \n"]]], "page_1203": [["block_0", [" 1190 \n"]], ["block_1", [" 107 . (a) bromine trifluoride; (b) sodium bromate; (c) phosphorus pentabromide; (d) sodium perchlorate; (e)\n"]], ["block_2", [" 109 . (a) I: 7+; (b) I: 7+; (c) Cl: 4+; (d) I: 3+; Cl: 1\u2212; (e) F: 0\n 111 . (a) spd hybridized; (b) spdhybridized; (c) sphybridized; (d) sphybridized; (e) spdhybridized;\n 113 . (a) nonpolar; (b) nonpolar; (c) polar; (d) nonpolar; (e) polar\n"]], ["block_3", [" 115 . The empirical formula is XeF6, and the balanced reactions are:\n"]], ["block_4", [" Chapter 19 \n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", [" 1 . (a) Sc: [Ar]4s3d; (b) Ti: [Ar]4s3d; (c) Cr: [Ar]4s3d; (d) Fe: [Ar]4s3d; (e) Ru: [Kr]5s4d\n"]], ["block_7", [" 3 . (a) La: [Xe]6s5d, La: [Xe]; (b) Sm: [Xe]6s4f, Sm: [Xe]4f; (c) Lu: [Xe]6s4f5d, Lu: [Xe]4f\n"]], ["block_8", [" 5 . Al is used because it is the strongest reducing agent and the only option listed that can provide sufficient\n"]], ["block_9", [" 7 . Mo\n 9 . The CaSiO3 slag is less dense than the molten iron, so it can easily be separated. Also, the floating slag\n"]], ["block_10", ["driving force to convert La(III) into La.\n"]], ["block_11", ["layer creates a barrier that prevents the molten iron from exposure to O2, which would oxidize the Fe back\n"]], ["block_12", [{"image_0": "1203_0.png", "coords": [96, 57, 213, 136]}]], ["block_13", ["(b)\n"]], ["block_14", [{"image_1": "1203_1.png", "coords": [96, 164, 213, 203]}]], ["block_15", ["(c)\n"]], ["block_16", [{"image_2": "1203_2.png", "coords": [96, 231, 213, 309]}]], ["block_17", ["(d)\n"]], ["block_18", [{"image_3": "1203_3.png", "coords": [96, 337, 213, 390]}]], ["block_19", ["(e)\n"]], ["block_20", [{"image_4": "1203_4.png", "coords": [96, 418, 213, 476]}]], ["block_21", ["potassium hypochlorite\n"]]], "page_1204": [["block_0", [" 11 . 2.57%\n 13 . 0.167 V\n 15 . E\u00b0 = \u22120.6 V, E\u00b0 is negative so this reduction is not spontaneous. E\u00b0 = +1.1 V\n 17 . (a)\n(b)\n"]], ["block_1", [" 19 . (a)\n"]], ["block_2", [" 21 . (a)\n(b)\n"]], ["block_3", [" 23 . As CNis added,\n"]], ["block_4", [" 25 . (a) Sc; (b) Ti; (c) V; (d) Cr; (e) Mn; (f) Feand Fe; (g) Coand Co; (h) Ni; (i) Cu\n"]], ["block_5", [" 27 . (a) 4, [Zn(OH)4]; (b) 6, [Pd(CN)6]; (c) 2, [AuCl2]; (d) 4, [Pt(NH3)2Cl2]; (e) 6, K[Cr(NH3)2Cl4]; (f) 6,\n"]], ["block_6", [" 29 . (a) [Pt(H2O)2Br2]:\n"]], ["block_7", ["to Fe2O3.\n"]], ["block_8", ["(f)\n"]], ["block_9", ["(b)\n(c) In acid\n"]], ["block_10", ["solution between pH 2 and pH 6,\nforms\nwhich is in equilibrium with dichromate ion.\n"]], ["block_11", ["The reaction is\nAt other acidic pHs, the reaction is\n"]], ["block_12", ["As more CNis added,\n"]], ["block_13", ["[Co(NH3)6][Cr(CN)6]; (g) 6, [Co(en)2Br2]NO3\n"]], ["block_14", [{"image_0": "1204_0.png", "coords": [91, 496, 325, 545]}]], ["block_15", ["(b) [Pt(NH3)(py)(Cl)(Br)]:\n"]], ["block_16", [{"image_1": "1204_1.png", "coords": [91, 573, 325, 611]}]], ["block_17", ["(c) [Zn(NH3)3Cl]:\n"]], ["block_18", [{"image_2": "1204_2.png", "coords": [91, 639, 208, 698]}]], ["block_19", ["(d) [Pt(NH3)3Cl]:\n"]], ["block_20", ["(e)\n"]], ["block_21", ["(e)\n"]], ["block_22", ["(d)\n"]], ["block_23", ["(g)\n"]], ["block_24", ["(d)\n"]], ["block_25", ["(f)\n"]], ["block_26", ["(c)\n"]], ["block_27", ["(f)\n"]], ["block_28", ["(c)\n"]], ["block_29", ["(d)\n"]], ["block_30", ["(e)\n"]], ["block_31", [" 1191 \n"]]], "page_1205": [["block_0", [" 1192 \n"]], ["block_1", [" 31 . (a) tricarbonatocobaltate(III) ion; (b) tetraaminecopper(II) ion; (c) tetraaminedibromocobalt(III) sulfate; (d)\n"]], ["block_2", [" 33 . (a) none; (b) none; (c) The two Cl ligands can be cis or trans. When they are cis, there will also be an optical\n"]], ["block_3", [" 35 .\n"]], ["block_4", [" 37 .\n"]], ["block_5", [" Access for free at openstax.org \n"]], ["block_6", [{"image_0": "1205_0.png", "coords": [91, 57, 208, 109]}]], ["block_7", ["(e) [Ni(H2O)4Cl2]:\n"]], ["block_8", [{"image_1": "1205_1.png", "coords": [91, 137, 325, 211]}]], ["block_9", ["(f) [Co(C2O4)2Cl2]:\n"]], ["block_10", [{"image_2": "1205_2.png", "coords": [91, 239, 442, 409]}]], ["block_11", ["tetraamineplatinum(II) tetrachloroplatinate(II); (e) tris-(ethylenediamine)chromium(III) nitrate; (f)\ndiaminedibromopalladium(II); (g) potassium pentachlorocuprate(II); (h) diaminedichlorozinc(II)\n"]], ["block_12", ["isomer.\n"]], ["block_13", [{"image_3": "1205_3.png", "coords": [91, 481, 442, 705]}]]], "page_1206": [["block_0", [" 39 . [Co(H2O)6]Cl2 with three unpaired electrons.\n 41 . (a) 4; (b) 2; (c) 1; (d) 5; (e) 0\n 43 . (a) [Fe(CN)6]; (b) [Co(NH3)6]; (c) [Mn(CN)6]\n"]], ["block_1", [" 45 . The complex does not have any unpaired electrons. The complex does not have any geometric isomers,\n"]], ["block_2", [" 47 . No. Auhas a complete 5d sublevel.\n"]], ["block_3", [" Chapter 20 \n"]], ["block_4", [" 1 . There are several sets of answers; one is:\n"]], ["block_5", [" 3 . Both reactions result in bromine being incorporated into the structure of the product. The difference is the\n"]], ["block_6", [" 5 . Unbranched alkanes have free rotation about the C\u2013C bonds, yielding all orientations of the substituents\n"]], ["block_7", [" 7 . They are the same compound because each is a saturated hydrocarbon containing an unbranched chain of\n"]], ["block_8", [" 9 . (a) C6H14\n"]], ["block_9", ["(a) C5H12\n"]], ["block_10", [{"image_0": "1206_0.png", "coords": [89, 316, 314, 368]}]], ["block_11", ["(b) C5H10\n"]], ["block_12", [{"image_1": "1206_1.png", "coords": [89, 396, 314, 449]}]], ["block_13", ["(c) C5H8\n"]], ["block_14", [{"image_2": "1206_2.png", "coords": [89, 477, 314, 533]}]], ["block_15", ["way in which that incorporation takes place. In the saturated hydrocarbon, an existing C\u2013H bond is\nbroken, and a bond between the C and the Br can then be formed. In the unsaturated hydrocarbon, the\nonly bond broken in the hydrocarbon is the \u03c0 bond whose electrons can be used to form a bond to one of\nthe bromine atoms in Br2 (the electrons from the Br\u2013Br bond form the other C\u2013Br bond on the other\ncarbon that was part of the \u03c0 bond in the starting unsaturated hydrocarbon).\n"]], ["block_16", ["about these bonds equivalent, interchangeable by rotation. In the unbranched alkenes, the inability to\nrotate about the\nbond results in fixed (unchanging) substituent orientations, thus permitting\n"]], ["block_17", ["different isomers. Since these concepts pertain to phenomena at the molecular level, this explanation\ninvolves the microscopic domain.\n"]], ["block_18", ["six carbon atoms.\n"]], ["block_19", [{"image_3": "1206_3.png", "coords": [91, 57, 451, 180]}]], ["block_20", ["but the mirror image is nonsuperimposable, so it has an optical isomer.\n"]], ["block_21", [" 1193 \n"]]], "page_1207": [["block_0", [" 1194 \n"]], ["block_1", [" 11 . (a) 2,2-dibromobutane; (b) 2-chloro-2-methylpropane; (c) 2-methylbutane; (d) 1-butyne; (e)\n"]], ["block_2", [" Access for free at openstax.org \n"]], ["block_3", [{"image_0": "1207_0.png", "coords": [89, 57, 314, 112]}]], ["block_4", ["(b) C6H14\n"]], ["block_5", [{"image_1": "1207_1.png", "coords": [89, 140, 314, 235]}]], ["block_6", ["(c) C6H12\n"]], ["block_7", [{"image_2": "1207_2.png", "coords": [89, 263, 314, 333]}]], ["block_8", ["(d) C6H12\n"]], ["block_9", [{"image_3": "1207_3.png", "coords": [89, 361, 314, 453]}]], ["block_10", ["(e) C6H10\n"]], ["block_11", [{"image_4": "1207_4.png", "coords": [89, 481, 314, 535]}]], ["block_12", ["(f) C6H10\n"]], ["block_13", [{"image_5": "1207_5.png", "coords": [89, 563, 314, 656]}]], ["block_14", ["4-fluoro-4-methyl-1-octyne; (f) trans-1-chloropropene; (g) 4-methyl-1-pentene\n"]]], "page_1208": [["block_0", [" 13 .\n"]], ["block_1", [" 15 .\n"]], ["block_2", [" 17 . (a) 2,2,4-trimethylpentane; (b) 2,2,3-trimethylpentane, 2,3,4-trimethylpentane, and\n"]], ["block_3", [" 19 .\n"]], ["block_4", [" 21 . In the following, the carbon backbone and the appropriate number of hydrogen atoms are shown in\n"]], ["block_5", [{"image_0": "1208_0.png", "coords": [91, 63, 442, 171]}]], ["block_6", [{"image_1": "1208_1.png", "coords": [91, 181, 316, 244]}]], ["block_7", ["2,3,3-trimethylpentane:\n"]], ["block_8", [{"image_2": "1208_2.png", "coords": [91, 272, 463, 333]}]], ["block_9", [{"image_3": "1208_3.png", "coords": [91, 342, 451, 514]}]], ["block_10", ["condensed form:\n"]], ["block_11", [{"image_4": "1208_4.png", "coords": [91, 542, 451, 714]}]], ["block_12", [" 1195 \n"]]], "page_1209": [["block_0", [" 1196 \n"]], ["block_1", [" 23 .\n"]], ["block_2", [" 25 . (a)\n"]], ["block_3", [" 27 . 65.2 g\n 29 . 9.328\n10kg\n"]], ["block_4", [" 31 . (a) ethyl alcohol, ethanol: CH3CH2OH; (b) methyl alcohol, methanol: CH3OH; (c) ethylene glycol,\n"]], ["block_5", [" 33 . (a) 1-ethoxybutane, butyl ethyl ether; (b) 1-ethoxypropane, ethyl propyl ether; (c) 1-methoxypropane,\n"]], ["block_6", [" 35 . HOCH2CH2OH, two alcohol groups; CH3OCH2OH, ether and alcohol groups\n 37 . (a)\n"]], ["block_7", [" 39 . (a)\n"]], ["block_8", [" 41 . (a)\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", [{"image_0": "1209_0.png", "coords": [91, 63, 316, 146]}]], ["block_11", ["In acetylene, the bonding uses sp hybrids on carbon atoms and s orbitals on hydrogen atoms. In benzene,\nthe carbon atoms are sphybridized.\n"]], ["block_12", [{"image_1": "1209_1.png", "coords": [91, 187, 451, 241]}]], ["block_13", ["(b)\n"]], ["block_14", [{"image_2": "1209_2.png", "coords": [91, 269, 463, 323]}]], ["block_15", ["ethanediol: HOCH2CH2OH; (d) isopropyl alcohol, 2-propanol: CH3CH(OH)CH3; (e) glycerine,\nl,2,3-trihydroxypropane: HOCH2CH(OH)CH2OH\n"]], ["block_16", ["methyl propyl ether\n"]], ["block_17", [{"image_3": "1209_3.png", "coords": [91, 439, 442, 492]}]], ["block_18", ["(b) 4.593\n10L\n"]], ["block_19", [{"image_4": "1209_4.png", "coords": [91, 533, 451, 605]}]], ["block_20", ["(b)\n"]], ["block_21", [{"image_5": "1209_5.png", "coords": [91, 633, 442, 696]}]]], "page_1210": [["block_0", [" 43 . A ketone contains a group bonded to two additional carbon atoms; thus, a minimum of three carbon\n"]], ["block_1", [" 45 . Since they are both carboxylic acids, they each contain the \u2013COOH functional group and its\n"]], ["block_2", [" 47 . (a) CH3CH(OH)CH3: all carbons are tetrahedral; (b)\nthe end carbons are tetrahedral and the\n"]], ["block_3", [" 49 .\n"]], ["block_4", [" 51 . (a)\n"]], ["block_5", [{"image_0": "1210_0.png", "coords": [91, 57, 316, 99]}]], ["block_6", ["(b)\n"]], ["block_7", [{"image_1": "1210_1.png", "coords": [91, 127, 316, 170]}]], ["block_8", ["(c)\n"]], ["block_9", [{"image_2": "1210_2.png", "coords": [91, 198, 316, 242]}]], ["block_10", ["atoms are needed.\n"]], ["block_11", ["characteristics. The difference is the hydrocarbon chain in a saturated fatty acid contains no double or\ntriple bonds, whereas the hydrocarbon chain in an unsaturated fatty acid contains one or more multiple\nbonds.\n"]], ["block_12", ["central carbon is trigonal planar; (c) CH3OCH3: all are tetrahedral; (d) CH3COOH: the methyl carbon is\ntetrahedral and the acid carbon is trigonal planar; (e) CH3CH2CH2CH(CH3)CHCH2: all are tetrahedral\nexcept the right-most two carbons, which are trigonal planar\n"]], ["block_13", [{"image_3": "1210_3.png", "coords": [91, 377, 316, 447]}]], ["block_14", [{"image_4": "1210_4.png", "coords": [91, 463, 523, 515]}]], ["block_15", ["(b)\n"]], ["block_16", [{"image_5": "1210_5.png", "coords": [91, 544, 559, 607]}]], ["block_17", [" 1197 \n"]]], "page_1211": [["block_0", [" 1198 \n"]], ["block_1", [" 53 .\n"]], ["block_2", [" 55 . Trimethyl amine: trigonal pyramidal, sp; trimethyl ammonium ion: tetrahedral, sp\n"]], ["block_3", [" 57 .\n"]], ["block_4", [" 59 .\n"]], ["block_5", [" 61 . CH3CH = CHCH3(sp) + Cl\nCH3CH(Cl)H(Cl)CH3(sp); 2C6H6(sp) + 15O2\n12CO2(sp) + 6H2O\n"]], ["block_6", [" 63 . The carbon in CO3, initially at sp, changes hybridization to sp in CO2.\n"]], ["block_7", [" Chapter 21 \n"]], ["block_8", [" 9 . (a), (b), (c), (d), and (e)\n 11 . (a) A nucleon is any particle contained in the nucleus of the atom, so it can refer to protons and neutrons.\n"]], ["block_9", [" Access for free at openstax.org \n"]], ["block_10", [" 1 . (a) sodium-24; (b) aluminum-29; (c) krypton-73; (d) iridium-194\n 3 . (a)\n(b)\n(c)\n(d)\n"]], ["block_11", [" 5 . (a)\n(b)\n(c)\n(d)\n"]], ["block_12", [" 7 . Nuclear reactions usually change one type of nucleus into another; chemical changes rearrange atoms.\n"]], ["block_13", ["Nuclear reactions involve much larger energies than chemical reactions and have measureable mass\nchanges.\n"]], ["block_14", [{"image_0": "1211_0.png", "coords": [91, 63, 451, 222]}]], ["block_15", [{"image_1": "1211_1.png", "coords": [91, 244, 316, 407]}]], ["block_16", [{"image_2": "1211_2.png", "coords": [91, 423, 487, 488]}]], ["block_17", ["(b) An \u03b1 particle is one product of natural radioactivity and is the nucleus of a helium atom. (c) A \u03b2 particle\nis a product of natural radioactivity and is a high-speed electron. (d) A positron is a particle with the same\nmass as an electron but with a positive charge. (e) Gamma rays compose electromagnetic radiation of high\nenergy and short wavelength. (f) Nuclide is a term used when referring to a single type of nucleus. (g) The\nmass number is the sum of the number of protons and the number of neutrons in an element. (h) The\natomic number is the number of protons in the nucleus of an element.\n"]]], "page_1212": [["block_0", [" 13 . (a)\n(b)\n(c)\n(d)\n"]], ["block_1", [" 15 . (a)\n(b)\n(c)\n(d)\n"]], ["block_2", [" 17 . (a) 148.8 MeV per atom; (b) 7.808 MeV/nucleon\n 19 . \u03b1 (helium nuclei), \u03b2 (electrons), \u03b2(positrons), and \u03b7 (neutrons) may be emitted from a radioactive\n"]], ["block_3", [" 21 . (a) conversion of a neutron to a proton:\n(b) conversion of a proton to a neutron; the\n"]], ["block_4", [" 23 . The electron pulled into the nucleus was most likely found in the 1s orbital. As an electron falls from a\n"]], ["block_5", [" 25 . Manganese-51 is most likely to decay by positron emission. The n:p ratio for Cr-53 is\n= 1.21; for\n"]], ["block_6", [" 27 . (a) \u03b2 decay; (b) \u03b1 decay; (c) positron emission; (d) \u03b2 decay; (e) \u03b1 decay\n 29 .\n"]], ["block_7", [" 31 . Half-life is the time required for half the atoms in a sample to decay. Example (answers may vary): For\n"]], ["block_8", [" 33 .\nor 97.3%\n"]], ["block_9", [" 35 . 2\n10y\n"]], ["block_10", [" 37 . 0.12 h\n"]], ["block_11", [" 39 . (a) 3.8 billion years; (b) The rock would be younger than the age calculated in part (a). If Sr was originally\n"]], ["block_12", [" 41 . c = 0; This shows that no Pu-239 could remain since the formation of the earth. Consequently, the\n"]], ["block_13", [" 43 . 17.5 MeV\n 45 . (a)\n(b)\n(c)\n"]], ["block_14", [" 47 . (a)\n(b)\n(c)\n"]], ["block_15", [" 49 . Two nuclei must collide for fusion to occur. High temperatures are required to give the nuclei enough\n"]], ["block_16", [" 51 . A nuclear reactor consists of the following:\n"]], ["block_17", ["element, all of which are particles; \u03b3 rays also may be emitted.\n"]], ["block_18", ["positron has the same mass as an electron and the same magnitude of positive charge as the electron has\nnegative charge; when the n:p ratio of a nucleus is too low, a proton is converted into a neutron with the\nemission of a positron:\n(c) In a proton-rich nucleus, an inner atomic electron can be\n"]], ["block_19", ["absorbed. In simplest form, this changes a proton into a neutron:\n"]], ["block_20", ["higher energy level to replace it, the difference in the energy of the replacement electron in its two energy\nlevels is given off as an X-ray.\n"]], ["block_21", ["Mn-51, it is\n= 1.04; for Fe-59, it is\n= 1.27. Positron decay occurs when the n:p ratio is low. Mn-51\n"]], ["block_22", ["has the lowest n:p ratio and therefore is most likely to decay by positron emission. Besides,\nis a stable\n"]], ["block_23", ["isotope, and\ndecays by beta emission.\n"]], ["block_24", ["C-14, the half-life is 5770 years. A 10-g sample of C-14 would contain 5 g of C-14 after 5770 years; a 0.20-g\nsample of C-14 would contain 0.10 g after 5770 years.\n"]], ["block_25", ["in the rock, the amount produced by radioactive decay would equal the present amount minus the initial\namount. As this amount would be smaller than the amount used to calculate the age of the rock and the\nage is proportional to the amount of Sr, the rock would be younger.\n"]], ["block_26", ["plutonium now present could not have been formed with the uranium.\n"]], ["block_27", ["kinetic energy to overcome the very strong repulsion resulting from their positive charges.\n"]], ["block_28", ["1.\nA nuclear fuel. A fissionable isotope must be present in large enough quantities to sustain a controlled\nchain reaction. The radioactive isotope is contained in tubes called fuel rods.\n"]], ["block_29", ["2.\nA moderator. A moderator slows neutrons produced by nuclear reactions so that they can be absorbed\nby the fuel and cause additional nuclear reactions.\n"]], ["block_30", ["3.\nA coolant. The coolant carries heat from the fission reaction to an external boiler and turbine where it\nis transformed into electricity.\n"]], ["block_31", ["4.\nA control system. The control system consists of control rods placed between fuel rods to absorb\nneutrons and is used to adjust the number of neutrons and keep the rate of the chain reaction at a safe\n"]], ["block_32", ["(d)\n"]], ["block_33", ["(d)\n"]], ["block_34", [" 1199 \n"]]], "page_1213": [["block_0", [" 1200 \n"]], ["block_1", [" 53 . The fission of uranium generates heat, which is carried to an external steam generator (boiler). The\n"]], ["block_2", [" 55 . Introduction of either radioactive Agor radioactive Clinto the solution containing the stated reaction,\n"]], ["block_3", [" 57 . (a)\n(b) 37.6 days\n"]], ["block_4", [" 59 . Alpha particles can be stopped by very thin shielding but have much stronger ionizing potential than beta\n"]], ["block_5", [" 61 . (a) 7.64\n10Bq; (b) 2.06\n10Ci\n"]], ["block_6", [" Access for free at openstax.org \n"]], ["block_7", ["resulting steam turns a turbine that powers an electrical generator.\n"]], ["block_8", ["with subsequent time given for equilibration, will produce a radioactive precipitate that was originally\ndevoid of radiation.\n"]], ["block_9", ["particles, X-rays, and \u03b3-rays. When inhaled, there is no protective skin covering the cells of the lungs,\nmaking it possible to damage the DNA in those cells and cause cancer.\n"]], ["block_10", ["5.\nA shield and containment system. The function of this component is to protect workers from\nradiation produced by the nuclear reactions and to withstand the high pressures resulting from high-\ntemperature reactions.\n"]], ["block_11", ["level.\n"]]], "page_1214": [["block_0", ["acid-ionization constant, Ka\n703\nacidic\n697\n"]], ["block_1", ["activation energy (Ea)\n626\n"]], ["block_2", ["\u03c3s molecular orbital\n395\n"]], ["block_3", [" INDEX \n"]], ["block_4", [" Symbols \n\u0394oct\n963\n"]], ["block_5", ["\u03c0* antibonding molecular\norbital\n396\n"]], ["block_6", ["\u03c3s*\u03c3s* molecular orbital\n396\n"]], ["block_7", [" A \nabsolute zero\n427\n"]], ["block_8", ["accuracy\n40\n"]], ["block_9", ["acid\n169\n"]], ["block_10", ["acid anhydrides\n879\n"]], ["block_11", ["acid ionization\n694\n"]], ["block_12", ["acid-base indicators\n734\n"]], ["block_13", ["acid-base reaction\n169\n"]], ["block_14", ["acids\n96\n"]], ["block_15", ["actinide series\n936\n"]], ["block_16", ["actinides\n87\n"]], ["block_17", ["actinoid series\n936\n"]], ["block_18", ["activated complex\n626\n"]], ["block_19", ["active electrodes\n823\n"]], ["block_20", ["activity\n582\n"]], ["block_21", ["actual yield\n188\n"]], ["block_22", ["addition reaction\n991\n"]], ["block_23", ["adhesive forces\n490\n"]], ["block_24", ["Alcohols\n995\n"]], ["block_25", ["aldehydes\n999\n"]], ["block_26", ["alkali metals\n87\n"]], ["block_27", ["Alkaline batteries\n835\n"]], ["block_28", ["alkaline earth metals\n87, 861\n"]], ["block_29", ["Alkanes\n978\n"]], ["block_30", ["alkenes\n988\n"]], ["block_31", ["alkyl group\n984\n"]], ["block_32", ["alkynes\n992\n"]], ["block_33", ["Allotropes\n866\n"]], ["block_34", ["alloys\n548\n"]], ["block_35", ["Alpha (\u03b1) decay\n1032\n"]], ["block_36", ["Alpha particles\n1029\n"]], ["block_37", ["alpha particles (\u03b1 particles)\n69\n"]], ["block_38", ["Amides\n1008\n"]], ["block_39", ["Avogadro\u2019s number (NA)\n121\n"]], ["block_40", ["base-ionization constant (Kb)\n704\n"]], ["block_41", ["Amines\n1005\n"]], ["block_42", ["Amontons\u2019s law\n426\n"]], ["block_43", ["amorphous\n872\n"]], ["block_44", ["amorphous solids\n510\n"]], ["block_45", ["amphiphilic\n587\n"]], ["block_46", ["amphiprotic\n695\n"]], ["block_47", ["amphoteric\n695\n"]], ["block_48", ["amplitude\n259\n"]], ["block_49", ["analyte\n191\n"]], ["block_50", ["anion\n72\n"]], ["block_51", ["anode\n821\n"]], ["block_52", ["antibonding orbitals\n396\n"]], ["block_53", ["antimatter\n1029\n"]], ["block_54", ["aqueous solution\n137\n"]], ["block_55", ["aromatic hydrocarbons\n993\n"]], ["block_56", ["Arrhenius\n694\n"]], ["block_57", ["Arrhenius equation\n627\n"]], ["block_58", ["atmosphere (atm)\n417\n"]], ["block_59", ["atom\n19, 62\n"]], ["block_60", ["atomic mass\n77\n"]], ["block_61", ["atomic mass unit (amu)\n71\n"]], ["block_62", ["atomic number (Z)\n72\n"]], ["block_63", ["atomic orbital\n280\n"]], ["block_64", ["Atwater system\n232\n"]], ["block_65", ["Aufbau principle\n288\n"]], ["block_66", ["autoionization\n695\n"]], ["block_67", ["Autumn\n481\n"]], ["block_68", ["average rate\n601\n"]], ["block_69", ["Avogadro\u2019s law\n433\n"]], ["block_70", ["axial position\n347\n"]], ["block_71", [" B \nbalanced\n161\n"]], ["block_72", ["Balmer\n269\n"]], ["block_73", ["band of stability\n1025\n"]], ["block_74", ["bar\n417\n"]], ["block_75", ["barometer\n418\n"]], ["block_76", ["Bartlett\n920\n"]], ["block_77", ["base\n171\n"]], ["block_78", ["base anhydrides\n904\n"]], ["block_79", ["Base ionization\n694\n"]], ["block_80", ["basic\n697\n"]], ["block_81", ["battery\n834\n"]], ["block_82", ["becquerel (Bq)\n1063\n"]], ["block_83", ["Beta (\u03b2) decay\n1032\n"]], ["block_84", ["Beta particles\n1029\n"]], ["block_85", ["bicarbonate anion\n891\n"]], ["block_86", ["Bidentate ligands\n950\n"]], ["block_87", ["bimolecular reaction\n631\n"]], ["block_88", ["binary acid\n102\n"]], ["block_89", ["binary compounds\n96\n"]], ["block_90", ["binding energy per nucleon\n1027\nbiofuel\n239\n"]], ["block_91", ["Bismuth\n866\n"]], ["block_92", ["blackbody\n264\n"]], ["block_93", ["body-centered cubic (BCC)\nsolid\n519\n"]], ["block_94", ["body-centered cubic unit cell\n519\nBohr\n269, 270\n"]], ["block_95", ["Bohr\u2019s model\n270\n"]], ["block_96", ["boiling point\n495\n"]], ["block_97", ["boiling point elevation\n571\n"]], ["block_98", ["boiling point elevation constant\n571\nBoltzmann\n788\n"]], ["block_99", ["bomb calorimeter\n230\n"]], ["block_100", ["bond angle\n343\n"]], ["block_101", ["bond dipole moment\n354\n"]], ["block_102", ["bond distance\n343\n"]], ["block_103", ["bond length\n317\n"]], ["block_104", ["bond order\n400\n"]], ["block_105", ["bonding orbitals\n396\n"]], ["block_106", ["Borates\n875\n"]], ["block_107", ["Born\n279\n"]], ["block_108", ["Born-Haber cycle\n341\n"]], ["block_109", ["Boyle\n694\n"]], ["block_110", ["Boyle\u2019s law\n431\n"]], ["block_111", ["Bragg\n530\n"]], ["block_112", ["Bragg equation\n530\n"]], ["block_113", ["Br\u00f8nsted-Lowry acid\n694\n"]], ["block_114", ["Br\u00f8nsted-Lowry base\n694\n"]], ["block_115", ["buffer\n724\n"]], ["block_116", ["buffer capacity\n727\n"]], ["block_117", [" Index \n 1201 \n"]]], "page_1215": [["block_0", ["cis configuration\n955\n"]], ["block_1", [" 1202 \n Index \n"]], ["block_2", ["buret\n191\n"]], ["block_3", [" C \ncalories (cal)\n216\n"]], ["block_4", ["calorimeter\n221\n"]], ["block_5", ["calorimetry\n221\n"]], ["block_6", ["capillary action\n490\n"]], ["block_7", ["carbonates\n891\n"]], ["block_8", ["carbonyl group\n999\n"]], ["block_9", ["carboxylic acids\n1003\n"]], ["block_10", ["Carnot\n787\n"]], ["block_11", ["catalysts\n607\n"]], ["block_12", ["cathode\n821\n"]], ["block_13", ["cathode ray\n66\n"]], ["block_14", ["cathodic protection\n842\n"]], ["block_15", ["cations\n72\n"]], ["block_16", ["cell notations\n822\n"]], ["block_17", ["cell potentials, Ecell\n824\n"]], ["block_18", ["cell schematics\n822\n"]], ["block_19", ["Celsius (\u00b0C)\n30\n"]], ["block_20", ["central metal\n949\n"]], ["block_21", ["Chadwick\n70, 1030\n"]], ["block_22", ["chain reaction\n1046\n"]], ["block_23", ["chalcogens\n87\n"]], ["block_24", ["Charles\u2019s law\n428\n"]], ["block_25", ["chelate\n950\n"]], ["block_26", ["chelating ligands\n950\n"]], ["block_27", ["chemical change\n24\n"]], ["block_28", ["chemical equation\n160\n"]], ["block_29", ["chemical property\n24\n"]], ["block_30", ["chemical reduction\n869\n"]], ["block_31", ["chemical symbol\n73\n"]], ["block_32", ["chemical thermodynamics\n233\n"]], ["block_33", ["chemistry\n11\n"]], ["block_34", ["chemotherapy\n1057\n"]], ["block_35", ["chlor-alkali process\n904\n"]], ["block_36", ["Clausius\n787\n"]], ["block_37", ["Clausius-Clapeyron equation\n496\ncoefficients\n160\n"]], ["block_38", ["cohesive forces\n488\n"]], ["block_39", ["colligative properties\n564\n"]], ["block_40", ["Collision theory\n625\n"]], ["block_41", ["colloidal dispersions\n583\n"]], ["block_42", ["colloids\n583\n"]], ["block_43", ["color change interval\n735\n"]], ["block_44", ["combustion analysis\n195\n"]], ["block_45", ["combustion reactions\n177\n"]], ["block_46", [" Access for free at openstax.org \n"]], ["block_47", [" D \nd orbitals\n280\n"]], ["block_48", ["d-block elements\n935\n"]], ["block_49", ["complete ionic equation\n165\n"]], ["block_50", ["compounds\n16\n"]], ["block_51", ["compressibility factor (Z)\n459\n"]], ["block_52", ["concentrated\n137\n"]], ["block_53", ["concentration\n137\n"]], ["block_54", ["concentration cell\n833\n"]], ["block_55", ["condensation\n493\n"]], ["block_56", ["containment system\n1051\n"]], ["block_57", ["continuous spectrum\n264\n"]], ["block_58", ["control rods\n1050\n"]], ["block_59", ["coordinate covalent bond\n763\n"]], ["block_60", ["coordination compounds\n938,\n"]], ["block_61", ["949\ncoordination isomers\n957\n"]], ["block_62", ["coordination number\n517, 949\n"]], ["block_63", ["coordination sphere\n949\n"]], ["block_64", ["core electrons\n291\n"]], ["block_65", ["Corrosion\n840\n"]], ["block_66", ["Cottrell\n589\n"]], ["block_67", ["covalent bonds\n92, 317\n"]], ["block_68", ["Covalent network solids\n512\n"]], ["block_69", ["covalent radius\n296\n"]], ["block_70", ["crenation\n578\n"]], ["block_71", ["Crick\n532\n"]], ["block_72", ["critical mass\n1047\n"]], ["block_73", ["critical point\n508\n"]], ["block_74", ["Cronin\n82\n"]], ["block_75", ["crystal field splitting\n963\n"]], ["block_76", ["crystal field theory\n962\n"]], ["block_77", ["crystalline solids\n510\n"]], ["block_78", ["cubic centimeter (cm3)\n31\n"]], ["block_79", ["cubic closest packing (CCP)\n520\n"]], ["block_80", ["cubic meter (m3)\n31\n"]], ["block_81", ["Curie\n1030\n"]], ["block_82", ["curie (Ci)\n1063\n"]], ["block_83", ["Dalton\n19\n"]], ["block_84", ["Dalton (Da)\n71\n"]], ["block_85", ["Dalton\u2019s atomic theory\n62\n"]], ["block_86", ["Dalton\u2019s law of partial\npressures\n440\n"]], ["block_87", ["daughter nuclide\n1031\n"]], ["block_88", ["Davisson\n276\n"]], ["block_89", ["Davy\n694\n"]], ["block_90", ["de Broglie\n275\n"]], ["block_91", ["Debye\n582\n"]], ["block_92", ["dissociation constant (Kd)\n765\n"]], ["block_93", [" E \neffective nuclear charge, Zeff\n298\neffusion\n450\n"]], ["block_94", ["eg orbitals\n963\n"]], ["block_95", ["degenerate orbitals\n283, 397\n"]], ["block_96", ["density\n31\n"]], ["block_97", ["deposition\n499\n"]], ["block_98", ["diamagnetic\n394\n"]], ["block_99", ["Diffraction\n530\n"]], ["block_100", ["diffusion\n449\n"]], ["block_101", ["dilute\n137\n"]], ["block_102", ["Dilution\n141\n"]], ["block_103", ["dimensional analysis\n42\n"]], ["block_104", ["dipole moment\n354\n"]], ["block_105", ["dipole-dipole attraction\n482\n"]], ["block_106", ["Diprotic acids\n722\n"]], ["block_107", ["diprotic base\n724\n"]], ["block_108", ["dispersed phase\n585\n"]], ["block_109", ["dispersion force\n478\n"]], ["block_110", ["dispersion medium\n585\n"]], ["block_111", ["disproportionation reactions\n879\ndissociation\n554\n"]], ["block_112", ["dissolved\n137\n"]], ["block_113", ["donor atom\n949\n"]], ["block_114", ["double bond\n325\n"]], ["block_115", ["Downs cell\n867\n"]], ["block_116", ["dry cell\n835\n"]], ["block_117", ["dynamic equilibrium\n493\n"]], ["block_118", ["electrode potential (EX)\n825\n"]], ["block_119", ["electrolysis\n843\n"]], ["block_120", ["electrolytes\n552\n"]], ["block_121", ["electromagnetic radiation\n258\n"]], ["block_122", ["electromagnetic spectrum\n259\n"]], ["block_123", ["electron\n67\n"]], ["block_124", ["electron affinity\n302\n"]], ["block_125", ["Electron capture\n1033\n"]], ["block_126", ["electron configuration\n288\n"]], ["block_127", ["electron volts (eV)\n1024\n"]], ["block_128", ["electron-pair geometry\n345\n"]], ["block_129", ["electronegativity\n319\n"]], ["block_130", ["electroplating\n846\n"]], ["block_131", ["element\n62\n"]], ["block_132", ["elementary reaction\n630\n"]], ["block_133", ["elements\n16\n"]], ["block_134", ["empirical formula\n81\n"]]], "page_1216": [["block_0", ["enthalpy (H)\n234\n"]], ["block_1", ["enthalpy change (\u0394H)\n234\n"]], ["block_2", ["entropy (S)\n787\n"]], ["block_3", ["equilibrium constant, K\n663\n"]], ["block_4", [" F \nf orbitals\n281\n"]], ["block_5", ["f-block elements\n935\n"]], ["block_6", ["formation constant (Kf)\n765\n"]], ["block_7", ["free energy change (\u0394G)\n797\n"]], ["block_8", ["empirical formula mass\n135\n"]], ["block_9", ["emulsifying agent\n586\n"]], ["block_10", ["emulsion\n586\n"]], ["block_11", ["enantiomers\n956\n"]], ["block_12", ["end point\n191\n"]], ["block_13", ["endothermic process\n215\n"]], ["block_14", ["Energy\n213\n"]], ["block_15", ["equatorial position\n347\n"]], ["block_16", ["equilibrium\n658\n"]], ["block_17", ["equivalence point\n191\n"]], ["block_18", ["esters\n1003\n"]], ["block_19", ["Ethers\n996\n"]], ["block_20", ["exact number\n34\n"]], ["block_21", ["excess reactant\n186\n"]], ["block_22", ["excited electronic state\n271\n"]], ["block_23", ["exothermic process\n215\n"]], ["block_24", ["expansion work\n233\n"]], ["block_25", ["extensive property\n25\n"]], ["block_26", ["external beam radiation\ntherapy\n1056\n"]], ["block_27", ["face-centered cubic (FCC) solid\n520\nface-centered cubic unit cell\n519\nfactor-label method\n42\n"]], ["block_28", ["Fahrenheit\n45\n"]], ["block_29", ["first law of thermodynamics\n233\nfirst transition series\n936\n"]], ["block_30", ["fissile\n1047\n"]], ["block_31", ["fission\n1044\n"]], ["block_32", ["fissionable\n1047\n"]], ["block_33", ["formal charge\n332\n"]], ["block_34", ["formula mass\n118\n"]], ["block_35", ["fourth transition series\n936\n"]], ["block_36", ["Franklin\n532\n"]], ["block_37", ["Frasch process\n913\n"]], ["block_38", ["free radicals\n330\n"]], ["block_39", ["freezing\n499\n"]], ["block_40", ["Gibbs free energy (G)\n797\n"]], ["block_41", ["half-life of a reaction (t1/2)\n622\n"]], ["block_42", ["Heat (q)\n215\n"]], ["block_43", ["freezing point\n499\n"]], ["block_44", ["freezing point depression\n573\n"]], ["block_45", ["freezing point depression\nconstant\n573\n"]], ["block_46", ["frequency\n259\n"]], ["block_47", ["frequency factor\n627\n"]], ["block_48", ["fuel cell\n839\n"]], ["block_49", ["Fuller\n313, 881\n"]], ["block_50", ["functional group\n988\n"]], ["block_51", ["fundamental unit of charge (e)\n71\nfusion\n1053\n"]], ["block_52", ["fusion reactor\n1054\n"]], ["block_53", [" G \ngalvanic cells\n821\n"]], ["block_54", ["galvanization\n842\n"]], ["block_55", ["Gamma emission (\u03b3 emission)\n1032\ngamma rays (\u03b3)\n1029\n"]], ["block_56", ["gas\n14\n"]], ["block_57", ["Gay-Lussac\u2019s law\n426\n"]], ["block_58", ["Geiger\n69\n"]], ["block_59", ["Geiger counter\n1062\n"]], ["block_60", ["Geim\n514, 882\n"]], ["block_61", ["gel\n590\n"]], ["block_62", ["Germer\n276\n"]], ["block_63", ["Gibbs\n797\n"]], ["block_64", ["Gouy\n394\n"]], ["block_65", ["Graham\u2019s law of 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changes,\n\u0394G\u00b0\n798\n"]], ["block_48", ["standard free energy of\nformation \u0394Gf\u00b0\n799\n"]], ["block_49", ["significant digits\n35\n"]], ["block_50", ["significant figures\n35\n"]], ["block_51", ["Silicates\n877\n"]], ["block_52", ["simple cubic structure\n517\n"]], ["block_53", ["simple cubic unit cell\n517\n"]], ["block_54", ["single bond\n324\n"]], ["block_55", ["Single-displacement\n(replacement) reactions\n177\n"]], ["block_56", ["skeletal structure\n979\n"]], ["block_57", ["Smalley\n329, 881\n"]], ["block_58", ["smelting\n940\n"]], ["block_59", ["Soddy\n70\n"]], ["block_60", ["solid\n14\n"]], ["block_61", ["Solomon\n448\n"]], ["block_62", ["solubility\n166, 555\n"]], ["block_63", ["soluble\n166\n"]], ["block_64", ["solute\n137\n"]], ["block_65", ["solution\n17\n"]], ["block_66", ["solvation\n550\n"]], ["block_67", ["solvent\n137\n"]], ["block_68", ["space lattice\n528\n"]], ["block_69", ["spatial isomers\n84\n"]], ["block_70", ["spectator ions\n165\n"]], ["block_71", ["spectrochemical series\n963\n"]], ["block_72", ["spin quantum number\n283\n"]], ["block_73", ["spontaneous process\n549, 784\n"]], ["block_74", ["standard cell potential, E\u00b0cell\n824\nstandard electrode potential,\nE\u00b0X\n825\n"]], ["block_75", ["Standard enthalpy of\ncombustion\n237\n"]], ["block_76", ["standard enthalpy of formation\n\u0394Hf\u00b0\u0394Hf\u00b0\n240\n"]], ["block_77", ["standard hydrogen electrode\n(SHE)\n824\n"]], ["block_78", [" T \nt2g orbitals\n963\n"]], ["block_79", ["standard molar volume\n436\n"]], ["block_80", ["standard state\n237\n"]], ["block_81", ["standard temperature and\npressure (STP)\n436\n"]], ["block_82", ["Standing waves\n263\n"]], ["block_83", ["state function\n234\n"]], ["block_84", ["stationary waves\n263\n"]], ["block_85", ["Steel\n942\n"]], ["block_86", ["stepwise ionization\n722\n"]], ["block_87", ["stoichiometric factors\n181\n"]], ["block_88", ["stoichiometry\n181\n"]], ["block_89", ["strong acids\n170\n"]], ["block_90", ["strong bases\n171\n"]], ["block_91", ["strong electrolyte\n552\n"]], ["block_92", ["strong nuclear force\n1023\n"]], ["block_93", ["strong-field ligands\n964\n"]], ["block_94", ["structural formula\n80\n"]], ["block_95", ["structural isomers\n83\n"]], ["block_96", ["subcritical mass\n1047\n"]], ["block_97", ["sublimation\n499\n"]], ["block_98", ["subshell\n280\n"]], ["block_99", ["substituents\n983\n"]], ["block_100", ["substitution reaction\n987\n"]], ["block_101", ["sulfates\n907\n"]], ["block_102", ["sulfites\n907\n"]], ["block_103", ["superconductor\n947\n"]], ["block_104", ["supercritical fluid\n508\n"]], ["block_105", ["supercritical mass\n1047\n"]], ["block_106", ["superoxides\n901\n"]], ["block_107", ["supersaturated\n555\n"]], ["block_108", ["Surface tension\n489\n"]], ["block_109", ["surroundings\n221\n"]], ["block_110", ["suspensions\n583\n"]], ["block_111", ["symbolic domain\n13\n"]], ["block_112", ["system\n221\n"]], ["block_113", ["temperature\n45, 213\n"]], ["block_114", ["termolecular reaction\n632\n"]], ["block_115", ["tetrahedral\n344\n"]], ["block_116", ["tetrahedral hole\n525\n"]], ["block_117", ["theoretical yield\n188\n"]], ["block_118", ["theories\n12\n"]], ["block_119", ["Thermal energy\n213\n"]], ["block_120", ["thermochemistry\n212\n"]], ["block_121", ["third law of thermodynamics\n795\nthird transition series\n936\n"]]], "page_1220": [["block_0", ["trans configuration\n955\n"]], ["block_1", ["Thomson\n66\n"]], ["block_2", ["titrant\n191\n"]], ["block_3", ["titration analysis\n191\n"]], ["block_4", ["titration curve\n730\n"]], ["block_5", ["torr\n419\n"]], ["block_6", ["transition metals\n87\n"]], ["block_7", ["transition state\n626\n"]], ["block_8", ["transmutation\n1042\n"]], ["block_9", ["transuranium elements\n1044\n"]], ["block_10", ["trigonal bipyramidal\n344\n"]], ["block_11", ["trigonal planar\n344\n"]], ["block_12", ["triple bond\n325\n"]], ["block_13", ["triple point\n506\n"]], ["block_14", ["triprotic acid\n724\n"]], ["block_15", ["Tyndall effect\n584\n"]], ["block_16", [" U \nuncertainty\n34\n"]], ["block_17", ["unified atomic mass unit (u)\n71\n"]], ["block_18", ["unimolecular reaction\n631\n"]], ["block_19", ["unit cell\n516\n"]], ["block_20", ["unit conversion factor\n42\n"]], ["block_21", ["urms\n456\n"]], ["block_22", ["van\u2019t Hoff factor (i)\n581\n"]], ["block_23", ["Units\n28\n"]], ["block_24", ["unsaturated\n555\n"]], ["block_25", [" V \n V acancies\n515\n"]], ["block_26", ["Valence bond theory\n376\n"]], ["block_27", ["valence electrons\n291\n"]], ["block_28", ["valence shell\n294\n"]], ["block_29", ["Valence shell electron-pair\nrepulsion theory (VSEPR\ntheory)\n343\n"]], ["block_30", ["van der Waals equation\n460\n"]], ["block_31", ["van der Waals forces\n478\n"]], ["block_32", ["vapor pressure\n493\n"]], ["block_33", ["vapor pressure of water\n443\n"]], ["block_34", ["vaporization\n493\n"]], ["block_35", ["vector\n354\n"]], ["block_36", ["viscosity\n487\n"]], ["block_37", ["voltaic cells\n821\n"]], ["block_38", ["Volume\n31\n"]], ["block_39", ["volume percentage\n146\n"]], ["block_40", ["work (w)\n213\n"]], ["block_41", [" W \n W atson\n532\n"]], ["block_42", ["wave\n258\n"]], ["block_43", ["wave-particle duality\n266\n"]], ["block_44", ["wavefunctions\n279\n"]], ["block_45", ["wavelength\n259\n"]], ["block_46", ["weak acids\n170\n"]], ["block_47", ["weak bases\n171\n"]], ["block_48", ["weak electrolyte\n552\n"]], ["block_49", ["weak-field ligands\n964\n"]], ["block_50", ["Weight\n15\n"]], ["block_51", ["Wilkins\n532\n"]], ["block_52", ["Wohler\n977\n"]], ["block_53", [" X \n X -ray crystallography\n530\n"]], ["block_54", [" Y \n Y oung\n258\n"]], ["block_55", [" Index \n 1207 \n"]]]}