Name:    Chapter 13 Online Practice

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

1.

What is the definition of molality?
 a. moles of solute per liter of solution b. grams of solute per kg of solution c. milligrams of solute per liter of solution d. moles of solute per liter of solvent e. moles of solute per kg of solvent

2.

The weight percent of concentrated H2SO4 is 96.0% and its density is 1.84 g/mL. What is the molarity of concentrated H2SO4?
 a. 9.79 M b. 12.0 M c. 18.0 M d. 53.2 M e. 245 M

3.

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

4.

If the concentration of potassium chloride in water is 113 ppm, what is the molarity of potassium chloride in water? The molar mass of KCl is 74.55 g/mol. Assume the density of the solution is 1.00 g/mL.
 a. 1.52 ´ 10-9 M b. 1.19 ´ 10-4 M c. 1.52 ´ 10-3 M d. 8.42 ´ 10-3 M e. 0.660 M

5.

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

6.

Two nonpolar solvents, such as hexane and carbon tetrachloride, may be miscible even though the enthalpy of mixing of these liquids might be small. A reason that mixing occurs is that mixtures have greater disorder than pure solvents. The tendency toward disorder is a thermodynamic function called ____.
 a. entropy b. enthalpy c. saturation d. adhesion e. cohesion

7.

Which substance will most likely NOT quantitatively follow Henry's law when dissolved in water?
 a. He b. O2 c. CH4 d. N2 e. NH3

8.

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

9.

The Henry's law constant for O2 in water at 25 °C is 1.66 ´ 10-6 M/mm Hg. What partial pressure of O2 is necessary to achieve an equilibrium concentration of 0.150 M O2?
 a. 2.49 ´ 10-7 mm Hg b. 6.23 ´ 10-6 mm Hg c. 1.11 ´ 10-5 mm Hg d. 9.04 ´ 104 mm Hg e. 4.02 ´ 106 mm Hg

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.

What is the equilibrium partial pressure of water vapor above a mixture of 24.0 g H2O and 48.0 g CH3CH2OH at 25 °C. The partial pressure of pure water at 25.0 °C is 23.8 mm Hg. Assume ideal behavior for the solution.
 a. 0.561 mm Hg b. 7.93 mm Hg c. 10.4 mm Hg d. 11.9 mm Hg e. 13.4 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 freezing point of a solution containing 4.78 grams naphthalene (molar mass = 128.2 g/mol) dissolved in 32.0 grams paradichlorobenzene? The freezing point of pure paradichlorobenzene is 53.0 °C and the freezing point depression constant, Kfp, is -7.10 °C/m.
 a. -1.63 °C b. 44.7 °C c. 46.9 °C d. 51.9 °C e. 52.1 °C

16.

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

17.

A 0.561 m solution of an unknown electrolyte depresses the freezing point of water by 2.93 °C. What is the van't Hoff factor for this electrolyte? The freezing point depression constant, Kfp, for water is -1.86 °C/m.
 a. 0.103 b. 1.92 c. 2.81 d. 3.05 e. 3.99

18.

What concentration unit is used in the calculation of osmotic pressure for a dilute solution?
 a. molality b. weight percent c. mass fraction d. mole fraction e. molarity

19.

A solution is prepared by dissolving 4.78 g of an unknown nonelectrolyte in enough water to make 0.500 L of solution. The osmotic pressure of the solution is 1.98 atm at 27 °C. What is the molar mass of the solute? (R = 0.08206 L·atm/mol·K)
 a. 24.9 g/mol b. 59.4 g/mol c. 119 g/mol d. 233 g/mol e. 466 g/mol

20.

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