Feedback Page Your feedback would be helpful as we continually strive to improve this laboratory manual. Please take a few minutes as you complete and write up experiments to share on this feedback page corrections, suggestions for improvements in the clarity of instructions, ideas for other experiments, comments on prelabs – whatever you wish. Keep this log as you go through the semester and at the last lab there will be an envelope you can place this sheet in anonymously. Use additional sheets if necessary. Thanks for your help. Dr. Buckley Experiment Corrections, suggestions, etc. Exp. 1 – Laboratory Safety Exp. 2 – Measurements, Accuracy, and Precision Exp. 3 – Using Physical Properties to Determine the Identity of an Unknown Exp. 4 – Sugar in Soft Drinks and Fruit Juices Exp. 5 – Separation of a Mixture Exp. 6 – Determination of an Empirical Chemical Formula Exp. 7 – Preparation of a Alum Exp. 8 – Metathesis Reactions
Exp. 9 – Molar Stoichiometry in a Chemical Reaction Exp. 10 – Determination of Acetic Acid in Vinegar Exp. 11 – Determination of the Enthalpy of Fusion of Water Exp. 12 – Comparison of the Energy Content of Fuels by Combustion Exp. 13 – Regularities in the Properties of Elements Exp. 14 – Molecular Modeling Exp. 15 – Molar Mass of a Volatile Liquid by the Dumas Method
Laboratory Equipment (not to scale) General Use Glassware: ←Griffin beakers – you will have 50 mL, 100 mL, 150 mL, 250 mL, and 400 mL Griffin beakers in your lab drawer ←Erlenmeyer flasks – you will have three 125 mL Erlenmeyer flasks in your drawer ←Test tubes – you will have six (all the same size) in your drawer. Size is measured as width x length in mm. Volume Measurement: ←Graduated cylinders – you will have 10 mL and 50 mL graduated cylinders in your drawer ←Pipette – will be distributed as needed. Various volumes and types available. ←Burette – will be distributed as needed. We typically use burettes which stand about 60 cm tall. Other Drawer Items: ←Plastic funnel for separation of solids from liquids ←Watch glass ←Glass stirring rod ←Metal spatula ←Test tube brush Equipment in Common Areas: ←Bunsen burner ← Jack Stand ← Hot plate or hot plate/stirrer ← Assorted clamps ← Metal rods for insertion into holes on table tops
cyclohexane solubility Refractive Index (if completed): The refractive index of my unknown is __________________ Unknown Identification Conclusion: The density, boiling point, solubility, and refractive index agree best with the compound _____________ which is my unknown # _________ . EXPERIMENT #3: USING PHYSICAL PROPERTIES TO DETERMINE THE IDENTITY OF AN UNKNOWN Post -Lab Based on your experiences with high altitude directions in cooking, pressure cookers, the textbook, and anything else you might know, would you expect the boiling points of these materials to be higher or lower if one conducted this experiment at the top of Pike’s Peak? If you don’t have actual experience with the high altitude cooking directions, just wander into a store and read a few boxes. Explain your reasoning. When determining the volume of an unknown, a student read the volume at the top of the meniscus rather than the bottom. Would this error increase, decrease, or not affect the measured volume? Explain your reasoning. If the student used the volume read in question 3 to calculate the density of the material, would the calculated density be high, low, or the same compared to the actual value? Explain your reasoning. Use the back of the page if necessary. Suppose in determining the density of an unknown the student measured the volume correctly but forgot to zero the balance before recording the mass. If the balance was reading -0.50 g before the student placed the object on the balance, how would the mistake of not zeroing the balance affect the calculated density? Explain your reasoning. Use the back of the page if necessary. This page is intentionally left blank.