Wolpa/AP Chemistry
Chapter 14: Solutions and Their Behavior
Problem Set 2
1. Which solution is expected to have the higher boiling point, 0.10 m Na2SO4 or
0.15 m sugar?
2. When a solution of sodium hydroxide is form a large amount of heat is
evolved. Is solid NaOH more or less soluble as the temperature is increased?
3. Instead of using NaCl to melt ice on your sidewalk, you decide to use CaCl2.
If you add 35.0 g of CaCl2 to 150.0 g water, what is the freezing point of the
solution?
4. Solutions of salts have boiling points higher than those calculated by using
the equation Tb = kb m (where m is the molality of the salt). Briefly explain this
observation.
5. Hydrochloric acid is sold as a concentrated aqueous solution. If the molarity
of commercial HCl is 12.0 and its density is 1.18 g/cm3, calculate
a. the molality of the solution
b. the mass percent of HCl in the solution.
6. A protozoan (single-celled animal) that normally lives in the ocean is placed in
the fresh water. Will it shrivel or burst? Explain briefly.
8. In chemical research we often send newly synthesized compounds to
commercial laboratories for analysis. These laboratories determine the mass
percent of C and H by burning the compound and collecting the evolved CO2 and
H2O. They determine the molar mass by measuring the osmotic pressure of a
solution of the compound. Calculate the empirical and molecular formulas of a
compound CxHyCr, given the following information:
a. The compound contains 73.94% C and 8.27% H; the remainder is chromium.
b. At 25 oC, the osmotic pressure of a solution containing 5.00 mg of the
unknown dissolved in 100.0 mL of chloroform is 3.17 mm Hg.