Question 1

What is the freezing point of a solution prepared from 50.0 g ethylene glycol (C2H6O2) and 85.0 g H2O? (For water, Kf = 1.86°C/m)

Accepted Answer

A)  17.6°C 
B)  -176°C 
C)  -1.50°C 
D)  1.50°C 
E)  -17.6°C

Question 2

Which substance is present in the largest proportion in a solution?

Accepted Answer

A)  salute 
B)  gas 
C)  solvent 
D)  solid 
E)  solute

Question 3

Diethyl ether has a vapor pressure of 400.0 torr at 18°C. When a sample of benzoic acid is dissolved in ether, the vapor pressure of the solution is 342 torr. What is the mole fraction of benzoic acid in the solution?

Accepted Answer

A)  0.0169 
B)  0.0197 
C)  0.145 
D)  0.855 
E)  0.045

Question 4

What is the freezing point of a solution made from 22.0 g of octane (C8H18) dissolved in 148.0 g of benzene? (For benzene, freezing point = 5.50°C; Kf = 5.12°C/m)

Accepted Answer

A)  -1.16°C 
B)  0.98°C 
C)  6.66°C 
D)  12.2°C 
E)  5.49°C

Question 5

Explain the following, on the basis of osmosis or osmotic pressure: In trees and plants, water is drawn from the soil up into the branches and leaves.

Accepted Answer

The answer of Explain the following, on the basis of...

Question 6

What is the value for the van't Hoff factor for all nonelectrolytes?

Accepted Answer

A)  -1 
B)  0 
C)  1 
D)  ½ 
E)  -½

Question 7

Carbon tetrachloride, once widely used in fire extinguishers and as a dry cleaning fluid, has been found to cause liver damage to those exposed to its vapors over long periods of time. What is the boiling point of a solution prepared by dissolving 375 g of sulfur (S8, 256.5 g/mol) in 1250 g of CCl4? (For CCl4, Kb = 5.05°C/m; boiling point of pure CCl4 = 76.7°C)

Accepted Answer

A)  70.8°C 
B)  75.2°C 
C)  78.2°C 
D)  82.6°C 
E)  85.7°C

Question 8

Hydration is the process in which organic solvent molecules surround a solute particle.

Accepted Answer

A) True 
 B)False

Question 9

When a nonvolatile solute is dissolved in a liquid, the vapor pressure exerted by the liquid decreases.

Accepted Answer

A) True 
 B)False

Question 10

What mass of water is required to dissolve 25.31 g of potassium nitrate (KNO3) in order to prepare a 0.1982 m solution?

Accepted Answer

A)  0.5101 kg 
B)  0.1277 kg 
C)  1.000. kg 
D)  1.263 kg 
E)  0.7917 kg

Question 11

The solubility of nitrogen gas in water at 25°C and a nitrogen pressure of 522 mmHg is 4.7 × 10-4 mol/L. What is the value of the Henry's law constant in mol L-1• atm-1?

Accepted Answer

A)  6.8 × 10-4 mol L-1• atm-1 
B)  4.7 × 10-4 mol L-1• atm-1 
C)  3.2 × 10-4 mol L-1• atm-1 
D)  9.0 × 10-7 mol L-1• atm-1 
E)  1.5 × 103 mol L-1• atm-1

Question 12

A solution is 40.00% by volume benzene (C6H6) in carbon tetrachloride at 20°C. The vapor pressure of pure benzene at this temperature is 74.61 mmHg and its density is 0.87865 g/cm3; the vapor pressure of pure carbon tetrachloride is 91.32 mmHg and its density is 1.5940 g/cm3. If this solution is ideal, its total vapor pressure at 20°C is

Accepted Answer

A)  84.64 mmHg. 
B)  84.30 mmHg. 
C)  82.96 mmHg. 
D)  81.63 mmHg. 
E)  165.93 mmHg.

Question 13

Which of these compounds is a nonelectrolyte?

Accepted Answer

A)  NaF 
B)  HNO3 
C)  CH3COOH (acetic acid) 
D)  NaOH 
E)  C6H12O6 (glucose)

Question 14

A solution of potassium hydroxide is in equilibrium with undissolved solute at 45°C. What will happen if the temperature is raised to 50°C? (ΔHsoln = -57.6 kJ/mol)

Accepted Answer

A)  The mass of undissolved KOH will increase. 
B)  The mass of undissolved KOH will decrease. 
C)  The mass of undissolved KOH will be unchanged. 
D)  The mass of water in the solution will increase. 
E)  The entropy of the system will decrease.

Question 15

Which is true regarding the solvation of a solute in a solvent?

Accepted Answer

A)  Separation of solute molecules from one another is an endothermic process, and separation of solvent molecules from one another is an exothermic process. 
B)  Separation of solute molecules from one another is an exothermic process, and separation of solvent molecules from one another is an endothermic process. 
C)  Separation of solute molecules from one another, and separation of solvent molecules from one another, are both endothermic processes. 
D)  Separation of solute molecules from one another, and separation of solvent molecules from one another, are both exothermic processes. 
E)  Separation of solute molecules from one another, and separation of solvent molecules from one another, both result in a decrease in entropy.

Question 16

The solubility of oxygen in lakes high in the Rocky Mountains is affected by the altitude. If the aqueous solubility of atmospheric O2 is 2.67 × 10-4 M at sea level and 25°C, what is the solubility of O2 at an elevation of 12,000 ft where the total pressure is 0.657 atm? Assume the temperature is 25°C, and that the mole fraction of O2 in air is 0.209 at both 12,000 ft and at sea level.

Accepted Answer

A)  1.75 × 10-4 M 
B)  2.67 × 10-4 M 
C)  3.66 × 10-5 M 
D)  4.06 × 10-4 M 
E)  5.58 × 10-5 M

Question 17

Below is a diagram representing two chambers containing solvent A, separated by a semipermeable membrane (a dashed line) which allows only solvent A to pass through.  If a solute X is added to the chamber on the left, which diagram below best represents how the system will respond in order to reach a new equilibrium?

Accepted Answer

A)   
B)   
C)   
D)   
E)

Question 18

Which of the following aqueous solutions should demonstrate the most nonideal behavior?

Accepted Answer

A)  0.1 M NaI 
B)  0.2 M CuSO4 
C)  0.5 M KBr 
D)  2.0 M CuCl2 
E)  2.5 M CsCl

Question 19

What is the molarity of a solution prepared by diluting 1.85 L of 6.5 M KOH to 11.0 L?

Accepted Answer

A)  0.28 M 
B)  0.91 M 
C)  1.1 M 
D)  3.1 M 
E)  3.9 M

Question 20

Explain the following, on the basis of osmosis or osmotic pressure: Drinking salt water actually dehydrates our tissues.

Accepted Answer

The answer of Explain the following, on the basis of...

Exam 13: Physical Properties of Solutions

What is the freezing point of a solution prepared from 50.0 g ethylene glycol (C₂H₆O₂) and 85.0 g H₂O? (For water, K_f = 1.86°C/m)