Amount of substance - wikipedia Amount of substance Amount of substance is a standards - defined quantity that measures the size of an ensemble of elementary entities, such as atoms, molecules, electrons, and other particles. It is sometimes referred to as chemical amount. The International System of Units ( SI ) defines the amount of substance to be proportional to the number of elementary entities present. The SI unit for amount of substance is the mole. It has the unit symbol mol. The proportionality constant is the inverse of the Avogadro constant. The mole is defined as the amount of substance that contains an equal number of elementary entities as there are atoms in 12 g of the isotope carbon - 12. This number is called Avogadro 's number and has the value 7023602214085700000 ♠ 6.022 140 857 ( 74 ) × 10. It is the numerical value of the Avogadro constant which has the unit mol, and relates the molar mass of an amount of substance to its mass. Therefore, the amount of substance of a sample is calculated as the sample mass divided by the molar mass of the substance. Amount of substance appears in thermodynamic relations such as the ideal gas law, and in stoichiometric relations between reacting molecules as in the law of multiple proportions. Another unit of amount of substance in use in chemical engineering in the United States is the pound - mole, having the symbol lb - mol. One pound - mole is 7002453592370000000 ♠ 453.592 37 mol. Contents 1 Terminology 2 Derived quantities 3 History 4 See also 5 Notes 6 References Terminology Look up amount of substance in Wiktionary, the free dictionary. When quoting an amount of substance, it is necessary to specify the entity involved, unless there is no risk of ambiguity. One mole of chlorine could refer either to chlorine atoms, as in 58.44 g of sodium chloride, or to chlorine molecules, as in 22.711 liters of chlorine gas at STP. The simplest way to avoid ambiguity is to replace the term substance by the name of the entity or to quote the empirical formula. For example : amount of chloroform ( molecules ), CHCl amount of sodium ( atoms ), Na amount of hydrogen ( atoms ), H n ( C H ) Amount of substance replaces the term `` number of moles '' which should no longer be used according to IUPAC recommendation. However, confusion can arise due to the everyday usage of the term amount and the term `` enplethy '' has been suggested for international usage to replace amount of substance. Derived quantities When amount of substance enters into a derived quantity, it is usually as the denominator : such quantities are known as molar quantities. For example, the quantity which describes the volume occupied by a given amount of substance is called the molar volume, while the quantity which describes the mass of a given amount of substance is the molar mass. Molar quantities are sometimes denoted by a subscript Latin `` m '' in the symbol, e.g. C, molar heat capacity at constant pressure : the subscript may be omitted if there is no risk of ambiguity, as is often the case in pure chemistry. The main derived quantity in which amount of substance enters into the numerator is amount of substance concentration, c. This name is often abbreviated to amount concentration, except in clinical chemistry where substance concentration is the preferred term to avoid ambiguity with mass concentration. The term molar concentration is incorrect, but commonly used. History The alchemists, and especially the early metallurgists, probably had some notion of amount of substance, but there are no surviving records of any generalization of the idea beyond a set of recipes. In 1758, Mikhail Lomonosov questioned the idea that mass was the only measure of the quantity of matter, but he did so only in relation to his theories on gravitation. The development of the concept of amount of substance was coincidental with, and vital to, the birth of modern chemistry. 1777 : Wenzel publishes Lessons on Affinity, in which he demonstrates that the proportions of the `` base component '' and the `` acid component '' ( cation and anion in modern terminology ) remain the same during reactions between two neutral salts. 1789 : Lavoisier publishes Treatise of Elementary Chemistry, introducing the concept of a chemical element and clarifying the Law of conservation of mass for chemical reactions. 1792 : Richter publishes the first volume of Stoichiometry or the Art of Measuring the Chemical Elements ( publication of subsequent volumes continues until 1802 ). The term `` stoichiometry '' is used for the first time. The first tables of equivalent weights are published for acid -- base reactions. Richter also notes that, for a given acid, the equivalent mass of the acid is proportional to the mass of oxygen in the base. 1794 : Proust 's Law of definite proportions generalizes the concept of equivalent weights to all types of chemical reaction, not simply acid -- base reactions. 1805 : Dalton publishes his first paper on modern atomic theory, including a `` Table of the relative weights of the ultimate particles of gaseous and other bodies ''. The concept of atoms raised the question of their weight. While many were skeptical about the reality of atoms, chemists quickly found atomic weights to be an invaluable tool in expressing stoichiometric relationships. 1808 : Publication of Dalton 's A New System of Chemical Philosophy, containing the first table of atomic weights ( based on H = 1 ). 1809 : Gay - Lussac 's Law of combining volumes, stating an integer relationship between the volumes of reactants and products in the chemical reactions of gases. 1811 : Avogadro hypothesizes that equal volumes of different gases ( at same temperature and pressure ) contain equal numbers of particles, now known as Avogadro 's law. 1813 / 1814 : Berzelius publishes the first of several tables of atomic weights based on the scale of O = 100. 1815 : Prout publishes his hypothesis that all atomic weights are integer multiple of the atomic weight of hydrogen. The hypothesis is later abandoned given the observed atomic weight of chlorine ( approx. 35.5 relative to hydrogen ). 1819 : Dulong -- Petit law relating the atomic weight of a solid element to its specific heat capacity. 1819 : Mitscherlich 's work on crystal isomorphism allows many chemical formulae to be clarified, resolving several ambiguities in the calculation of atomic weights. 1834 : Clapeyron states the ideal gas law. The ideal gas law was the first to be discovered of many relationships between the number of atoms or molecules in a system and other physical properties of the system, apart from its mass. However, this was not sufficient to convince all scientists of the existence of atoms and molecules, many considered it simply being a useful tool for calculation. 1834 : Faraday states his Laws of electrolysis, in particular that `` the chemical decomposing action of a current is constant for a constant quantity of electricity ''. 1856 : Krönig derives the ideal gas law from kinetic theory. Clausius publishes an independent derivation the following year. 1860 : The Karlsruhe Congress debates the relation between `` physical molecules '', `` chemical molecules '' and atoms, without reaching consensus. 1865 : Loschmidt makes the first estimate of the size of gas molecules and hence of number of molecules in a given volume of gas, now known as the Loschmidt constant. 1886 : va n't Hoff demonstrates the similarities in behaviour between dilute solutions and ideal gases. 1886 : Eugen Goldstein observed discrete particle rays in gas discharges that laid the foundation of mass spectrometry, a tool later used to establish the masses of atoms and molecules. 1887 : Arrhenius describes the dissociation of electrolyte in solution, resolving one of the problems in the study of colligative properties. 1893 : First recorded use of the term mole to describe a unit of amount of substance by Ostwald in a university textbook. 1897 : First recorded use of the term mole in English. By the turn of the twentieth century, the concept of atomic and molecular entities was generally accepted, but many questions remained, not least the size of atoms and their number in a given sample. The concurrent development of mass spectrometry, starting in 1886, supported the concept of atomic and molecular mass and provided a tool of direct relative measurement. 1905 : Einstein 's paper on Brownian motion dispels any last doubts on the physical reality of atoms, and opens the way for an accurate determination of their mass. 1909 : Perrin coins the name Avogadro constant and estimates its value. 1913 : Discovery of isotopes of non-radioactive elements by Soddy and Thomson. 1914 : Richards receives the Nobel Prize in Chemistry for `` his determinations of the atomic weight of a large number of elements ''. 1920 : Aston proposes the whole number rule, an updated version of Prout 's hypothesis. 1921 : Soddy receives the Nobel Prize in Chemistry `` for his work on the chemistry of radioactive substances and investigations into isotopes ''. 1922 : Aston receives the Nobel Prize in Chemistry `` for his discovery of isotopes in a large number of non-radioactive elements, and for his whole - number rule ''. 1926 : Perrin receives the Nobel Prize in Physics, in part for his work in measuring Avogadro 's constant. 1959 / 1960 : Unified atomic weight scale based on C = 12 adopted by IUPAP and IUPAC. 1968 : The mole is recommended for inclusion in the International System of Units ( SI ) by the International Committee for Weights and Measures ( CIPM ). 1972 : The mole is approved as the SI base unit of amount of substance. See also Amount fraction International System of Quantities Notes Jump up ^ This relation is exact, from the definition of the international avoirdupois pound. References ^ Jump up to : International Bureau of Weights and Measures ( 2006 ), The International System of Units ( SI ) ( PDF ) ( 8th ed. ), pp. 114 -- 15, ISBN 92 - 822 - 2213 - 6, archived ( PDF ) from the original on 2017 - 08 - 14 Jump up ^ International Union of Pure and Applied Chemistry Commission on Atomic Weights and Isotopic Abundances ( CIAAW ), P. ; Peiser, H.S. ( 1992 ). `` Atomic Weight : The Name, Its History, Definition and Units ''. Pure and Applied Chemistry. 64 ( 10 ) : 1535 -- 43. doi : 10.1351 / pac199264101535. Jump up ^ `` CODATA Value : Avogadro constant ''. The NIST Reference on Constants, Units, and Uncertainty. US National Institute of Standards and Technology. June 2015. Retrieved 2015 - 09 - 25. 2014 CODATA recommended values Jump up ^ Talty, John T. ( 1988 ). Industrial Hygiene Engineering : Recognition, Measurement, Evaluation, and Control. William Andrew. p. 142. ISBN 0 - 8155 - 1175 - 2. Jump up ^ Lee, C.C. ( 2005 ). Environmental Engineering Dictionary ( 4th ed. ). Rowman & Littlefield. p. 506. ISBN 0 - 86587 - 848 - X. Jump up ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. ( the `` Gold Book '' ) ( 1997 ). Online corrected version : ( 2006 -- ) `` amount of substance, n ''. Jump up ^ International Union of Pure and Applied Chemistry ( 1993 ). Quantities, Units and Symbols in Physical Chemistry, 2nd edition, Oxford : Blackwell Science. ISBN 0 - 632 - 03583 - 8. p. 46. Electronic version. Jump up ^ `` E.R. Cohen, T. Cvitas, J.G. Frey, B. Holmström, K. Kuchitsu, R. Marquardt, I. Mills, F. Pavese, M. Quack, J. Stohner, H.L. Strauss, M. Takami, and A.J. Thor, `` Quantities, Units and Symbols in Physical Chemistry '', IUPAC Green Book, 3rd Edition, 2nd Printing, IUPAC & RSC Publishing, Cambridge ( 2008 ) '' ( PDF ). ^ Jump up to : International Union of Pure and Applied Chemistry ( 1993 ). Quantities, Units and Symbols in Physical Chemistry, 2nd edition, Oxford : Blackwell Science. ISBN 0 - 632 - 03583 - 8. p. 7. Electronic version. Jump up ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. ( the `` Gold Book '' ) ( 1997 ). Online corrected version : ( 2006 -- ) `` amount - of - substance concentration ''. Jump up ^ International Union of Pure and Applied Chemistry ( 1996 ). `` Glossary of Terms in Quantities and Units in Clinical Chemistry '' ( PDF ). Pure Appl. Chem. 68 : 957 -- 1000. Jump up ^ `` Molar concentration '' should refer to a concentration per mole, i.e. an amount fraction. The use of molar as a unit, equal to 1 mol / dm, symbol M, is frequent, but, as of May 2007, not condoned by IUPAC : International Union of Pure and Applied Chemistry ( 1993 ). Quantities, Units and Symbols in Physical Chemistry, 2nd edition, Oxford : Blackwell Science. ISBN 0 - 632 - 03583 - 8. p. 42 ( n. 15 ). Electronic version. Jump up ^ Lomonosov, Mikhail ( 1970 ). `` On the Relation of the Amount of Material and Weight ''. In Leicester, Henry M. Mikhail Vasil'evich Lomonosov on the Corpuscular Theory. Cambridge, MA : Harvard University Press. pp. 224 -- 33 -- via Internet Archive. ^ Jump up to : `` Atome ''. Grand dictionnaire universel du XIXe siècle. Paris : Pierre Larousse. 1 : 868 -- 73. 1866... ( in French ) Jump up ^ Lavoisier, Antoine ( 1789 ). Traité élémentaire de chimie, présenté dans un ordre nouveau et d'après les découvertes modernes. Paris : Chez Cuchet... ( in French ) Jump up ^ Dalton, John ( 1805 ). `` On the Absorption of Gases by Water and Other Liquids ''. Memoirs of the Literary and Philosophical Society of Manchester, 2nd Series. 1 : 271 -- 87. Jump up ^ Dalton, John ( 1808 ). A New System of Chemical Philosophy. Manchester. Jump up ^ Gay - Lussac, Joseph Louis ( 1809 ). `` Memoire sur la combinaison des substances gazeuses, les unes avec les autres ''. Mémoires de la Société d'Arcueil. 2 : 207. English translation. Jump up ^ Avogadro, Amedeo ( 1811 ). `` Essai d'une maniere de determiner les masses relatives des molecules elementaires des corps, et les proportions selon lesquelles elles entrent dans ces combinaisons ''. Journal de Physique. 73 : 58 -- 76. English translation. Jump up ^ Excerpts from Berzelius ' essay : Part II ; Part III. Jump up ^ Berzelius ' first atomic weight measurements were published in Swedish in 1810 : Hisinger, W. ; Berzelius, J.J. ( 1810 ). `` Forsok rorande de bestamda proportioner, havari den oorganiska naturens bestandsdelar finnas forenada ''. Afh. Fys., Kemi Mineral. 3 : 162. Jump up ^ Prout, William ( 1815 ). `` On the relation between the specific gravities of bodies in their gaseous state and the weights of their atoms ''. Annals of Philosophy. 6 : 321 -- 30. Jump up ^ Petit, Alexis Thérèse ; Dulong, Pierre - Louis ( 1819 ). `` Recherches sur quelques points importants de la Théorie de la Chaleur ''. Annales de Chimie et de Physique. 10 : 395 -- 413. English translation Jump up ^ Clapeyron, Émile ( 1834 ). `` Puissance motrice de la chaleur ''. Journal de l'École Royale Polytechnique. 14 ( 23 ) : 153 -- 90. Jump up ^ Faraday, Michael ( 1834 ). `` On Electrical Decomposition ''. Philosophical Transactions of the Royal Society. 124 : 77 -- 122. doi : 10.1098 / rstl. 1834.0008. Jump up ^ Krönig, August ( 1856 ). `` Grundzüge einer Theorie der Gase ''. Annalen der Physik. 99 ( 10 ) : 315 -- 22. Bibcode : 1856AnP... 175... 315K. doi : 10.1002 / andp. 18561751008. Jump up ^ Clausius, Rudolf ( 1857 ). `` Ueber die Art der Bewegung, welche wir Wärme nennen ''. Annalen der Physik. 176 ( 3 ) : 353 -- 79. Bibcode : 1857AnP... 176... 353C. doi : 10.1002 / andp. 18571760302. Jump up ^ Wurtz 's Account of the Sessions of the International Congress of Chemists in Karlsruhe, on 3, 4, and 5 September 1860. Jump up ^ Loschmidt, J. ( 1865 ). `` Zur Grösse der Luftmoleküle ''. Sitzungsberichte der kaiserlichen Akademie der Wissenschaften Wien. 52 ( 2 ) : 395 -- 413. English translation Archived February 7, 2006, at the Wayback Machine... Jump up ^ Arrhenius, Svante ( 1887 ). Zeitschrift für Physikalische Chemie. 1 : 631. CS1 maint : Untitled periodical ( link ) English translation. Jump up ^ Ostwald, Wilhelm ( 1893 ). Hand - und Hilfsbuch zur ausführung physiko - chemischer Messungen. Leipzig. Jump up ^ Helm, Georg ( 1897 ). The Principles of Mathematical Chemistry : The Energetics of Chemical Phenomena. ( Transl. Livingston, J. ; Morgan, R. ). New York : Wiley. p. 6. Jump up ^ Einstein, Albert ( 1905 ). `` Über die von der molekularkinetischen Theorie der Wärme geforderte Bewegung von in ruhenden Flüssigkeiten suspendierten Teilchen '' ( PDF ). Annalen der Physik. 17 ( 8 ) : 549 -- 60. Bibcode : 1905AnP... 322... 549E. doi : 10.1002 / andp. 19053220806. Jump up ^ Perrin, Jean ( 1909 ). `` Mouvement brownien et réalité moléculaire ''. Annales de Chimie et de Physique. 8 Série. 18 : 1 -- 114. Extract in English, translation by Frederick Soddy. Jump up ^ Soddy, Frederick ( 1913 ). `` The Radio - elements and the Periodic Law ''. Chemical News. 107 : 97 -- 99. Jump up ^ Thomson, J.J. ( 1913 ). `` Rays of positive electricity ''. Proceedings of the Royal Society A. 89 ( 607 ) : 1 -- 20. Bibcode : 1913RSPSA... 89... 1T. doi : 10.1098 / rspa. 1913.0057. Jump up ^ Söderbaum, H.G. ( November 11, 1915 ). Statement regarding the 1914 Nobel Prize in Chemistry. Jump up ^ Aston, Francis W. ( 1920 ). `` The constitution of atmospheric neon ''. Philosophical Magazine. 39 ( 6 ) : 449 -- 55. doi : 10.1080 / 14786440408636058. Jump up ^ Söderbaum, H.G. ( December 10, 1921 ). Presentation Speech for the 1921 Nobel Prize in Chemistry. Jump up ^ Söderbaum, H.G. ( December 10, 1922 ). Presentation Speech for the 1922 Nobel Prize in Chemistry. Jump up ^ Oseen, C.W. ( December 10, 1926 ). Presentation Speech for the 1926 Nobel Prize in Physics. Jump up ^ Holden, Norman E. ( 2004 ). `` Atomic Weights and the International Committee -- A Historical Review ''. Chemistry International. 26 ( 1 ) : 4 -- 7. Mole concepts Physical quantities Mass concentration Molar concentration Molality Mass Volume Density Mole fraction Mass fraction Amount of substance Molar mass Atomic mass Particle number Avogadro constant Pressure Kelvin temperature Gas constant Molar volume Specific volume Laws Charles 's law Boyle 's law Gay - Lussac 's law Combined gas law Ideal gas law SI base quantities Base quantity Quantity SI unit Name Symbol Dimension symbol Unit name ( symbol ) Example length l, x, r, ( etc. ) metre ( m ) r = 10 m mass m kilogram ( kg ) m = 10 kg time, duration second ( s ) t = 10 s electric current I, i I ampere ( A ) I = 10 A thermodynamic temperature Θ kelvin ( K ) T = 10 K amount of substance n mole ( mol ) n = 10 mol luminous intensity J candela ( cd ) I = 10 cd Specification The quantity ( not the unit ) can have a specification : T = 300 K Derived quantity Definition A quantity Q is expressed in the base quantities : Q = f ( l, m, t, I, T, n, I v ) ( displaystyle Q = f left ( ( mathit ( l, m, t, I, T, n, I ) ) mathrm ( _ ( v ) ) \right ) ) Derived dimension dim Q = L M T I Θ N J ( Superscripts a -- g are algebraic exponents, usually a positive, negative or zero integer. ) Example Quantity acceleration = l t, dim acceleration = L T possible units : m s, km Ms, etc. See also History of the metric system International System of Quantities Proposed redefinitions Systems of measurement Book Outline Retrieved from `` https://en.wikipedia.org/w/index.php?title=Amount_of_substance&oldid=801256861 '' Categories : Amount of substance SI base quantities Hidden categories : Articles with French - language external links Webarchive template wayback links CS1 maint : Untitled periodical Talk Contents About Wikipedia Bân - lâm - gú Беларуская Boarisch Brezhoneg Català Čeština Dansk Deutsch Eesti Español Esperanto فارسی Français 한국어 हिन्दी Hrvatski Bahasa Indonesia Italiano Latviešu Magyar Македонски Bahasa Melayu Nederlands 日本 語 Nordfriisk Norsk Norsk nynorsk Plattdüütsch Polski Português Română Русский Scots Simple English Slovenčina Српски / srpski Srpskohrvatski / српскохрватски Suomi Svenska தமிழ் Українська 文言 Winaray 粵語 中文 Edit links This page was last edited on 18 September 2017, at 16 : 48. 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Question: which is a metric unit of amount of a pure substance
Answer: the mole