Name:    Practice Test - Colligative Properties

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.

1.

To prepare 1.000 kg of 5.5% by mass KCl(aq), one may dissolve
 a. 994.5 g KCl in 5.5 g of water. b. 5.5 g KCl in 994.5 g of water. c. 5.5 g KCl in 1000.0 g of water. d. 55 g KCl in 945 g of water. e. 55.0 g KCl in 1000.0 g of water.

2.

What is the molality of 13.82% by mass sulfuric acid? The molar mass of H2SO4 is 98.08 g/mol.
 a. 0.1409 m b. 1.409 m c. 1.635 m d. 13.55 m e. 15.73 m

3.

What is the mole fraction of MgCl2 in a solution that is 11.04% by mass MgCl2(aq)? The molar mass of MgCl2 is 95.21 g/mol.
 a. 0.02295 b. 0.02349 c. 0.1104 d. 0.1160 e. 1.303

4.

What is the weight percent of ammonia in 3.33 m NH3(aq)?
 a. 0.332% b. 5.37% c. 5.67% d. 6.01% e. 56.7%

5.

A solution is prepared by mixing 66.7 g H2O with 33.3 g HOCH2CH2OH (ethylene glycol). What is the concentration of ethylene glycol in units of molality? The molar masses of water and ethylene glycol are 18.02 g/mol and 62.07 g/mol, respectively.
 a. 0.127 m b. 0.333 m c. 4.99 m d. 5.36 m e. 8.04 m

6.

What mass of Cu(NO3)2 must be added to 1.00 kg H2O to prepare 97 ppm Cu2+(aq)?
 a. 3.3 x 10-4 g b. 5.2 x 10-4 g c. 9.7 x 10-3 g d. 0.033 g e. 0.29 g

7.

Which of the following statements are CORRECT?

 1. Solubility is the concentration of solute in equilibrium with undissolved solute in a saturated solution. 2. If two liquids mix to an appreciable extent to form a solution, they are immiscible. 3. If two liquids mix completely in any proportion to form a solution, the resulting solution is supersaturated.
 a. 1 only b. 2 only c. 3 only d. 1 and 2 e. 2 and 3

8.

The Henry's law constant for N2 in water at 37 °C is 8.2 ´ 10-7 M/mm Hg. What is the equilibrium concentration of N2 in water when the partial pressure of N2 is 634 mm Hg?
 a. 1.3 x 10-9 M b. 5.2 x 10-4 M c. 1.9 x 10-2 M d. 1.9 x 103 M e. 7.7 x 108 M

9.

Which action(s) will decrease the equilibrium concentration of a non-reacting gas in water?

 1. decreasing the temperature of the water 2. decreasing the volume of water 3. decreasing the pressure of the gas above the liquid
 a. 1 only b. 2 only c. 3 only d. 1 and 3 e. 1, 2, and 3

10.

Ideally, colligative properties depend only on the
 a. concentration of solute particles in a solution. b. identity of the solute particles in a solution. c. color of a solution. d. hydrated radii of the molecules or ions dissolved in a solution. e. partial pressure of the gases above the surface of a solution.

11.

The vapor pressure of pure water at 45 °C is 71.9 mm Hg. What is the vapor pressure of a mixture of 21.0 g sucrose (C12H22O11, molar mass 342.3 g/mol) and 79.0 g water?
 a. 0.992 mm Hg b. 15.1 mm Hg c. 19.1 mm Hg d. 55.8 mm Hg e. 70.9 mm Hg

12.

Which of the following aqueous solutions should have the lowest freezing point?
 a. pure H2O b. 1 m NaBr c. 1 m Ca(NO3)2 d. 1 m NH3 e. 1 m C6H12O6

13.

Which of the following aqueous solutions should have the lowest boiling point?
 a. 0.50 m KCl b. 0.50 m Na2SO4 c. 0.50 m CaBr2 d. 1.5 m KI e. 2.0 m C6H12O6

14.

The freezing point depression constant for water is -1.86 °C/m. At what temperature will a solution containing 7.99 g BaCl2 and 52.0 g H2O begin to freeze? Assume that no ion-pairing occurs between Ba2+ and Cl-.
 a. -4.12 °C b. -2.75 °C c. -1.37 °C d. -0.857 °C e. -0.248 °C

15.

What is the molar mass of a nonpolar molecular compound if 5.52 grams dissolved in 36.0 grams of benzene begins to freeze at -1.87 °C? The freezing point of pure benzene is 5.50 °C and the freezing point depression constant, Kfp, is -5.12 °C/m.
 a. 46.1 g/mol b. 107 g/mol c. 216 g/mol d. 221 g/mol e. 419 g/mol

16.

What is the boiling point of a solution containing 2.33 g of caffeine, C8H10N4O2, dissolved in 15.0 g of benzene? The boiling point of pure benzene is 80.1 °C and the boiling point elevation constant, Kbp, is 2.53 °C/m.
 a. 2.02 °C b. 78.1 °C c. 80.2 °C d. 82.1 °C e. 83.3 °C

17.

What mass of NaCl must be dissolved in 65.0 grams of water to lower the freezing point by 7.50 °C? The freezing point depression constant, Kfp, for water is -1.86 °C/m. Assume the van't Hoff factor for NaCl is 1.87.
 a. 0.140 g b. 1.76 g c. 4.55 g d. 8.19 g e. 15.3 g

18.

Which of the following is an application of osmotic pressure?
 a. salting meats for preservation b. mixing water and ethylene glycol in antifreeze c. pressurizing beverages with carbon dioxide d. salting icy roads e. using a pressure cooker to increase the boiling point of water

19.

All of the following are colloidal dispersions EXCEPT
 a. ice cubes. b. cheese. c. butter. d. clouds. e. shaving cream.

20.

Cheese and butter are colloidal dispersions that contain a liquid dispersed in a solid medium. This type of colloid is called a(n) ____.
 a. emulsion b. sol c. foam d. aerosol e. gel