______ pts. out of 100 possible pts. = % = Name:

Advanced Chemistry: Test #6 (Solution Chemistry)

Multiple Choice: Circle the letter of the best answer for each of the following.  (3 pts. each)

1. Which of the following statements is true?

a. Nitrogen gas must dissolve endothermically in water because there is an increase in entropy during the dissolution process.

b. Nitrogen gas must dissolve exothermically in water because there is an increase in entropy during the dissolution process.

c. Nitrogen gas must dissolve endothermically in water because there is a decrease in entropy during the dissolution process.

d. Nitrogen gas must dissolve exothermically in water because there is a decrease in entropy during the dissolution process.

e. The dissolution of nitrogen gas could be either endothermic or exothermic because there is an increase in entropy during the dissolution process.

2. As the temperature of water increases, the solubility of nitrogen gas:

a. increases, because as the temperature goes up the entropy change becomes less important

b. increases, because as the temperature goes up the entropy change becomes more important

c. decreases, because as the temperature goes up the entropy change becomes less important

d. decreases, because as the temperature goes up the entropy change becomes more important

e. remains the same because DS is zero for the dissolution process

3. NH₄Cl dissolves endothermically in water because:

a. the lattice energy is greater than the heat of hydration

b. the lattice energy is less than the heat of hydration

c. the hydration step is endothermic

d. the change in entropy for the process is negative

e. the change in enthalpy for the process is negative

4. As the temperature of water increases, the solubility of most solids:

a. increases, because as the temperature goes up the entropy change becomes less important

b. increases, because as the temperature goes up the entropy change becomes more important

c. decreases, because as the temperature goes up the entropy change becomes less important

d. decreases, because as the temperature goes up the entropy change becomes more important

e. remains the same because DS is zero for the dissolution process

5. Which of the following statements is true?

a. Solid calcium chloride must dissolve endothermically in water because there is an increase in entropy during the dissolution process.

b. Solid calcium chloride must dissolve exothermically in water because there is an increase in entropy during the dissolution process.

c. Solid calcium chloride must dissolve endothermically in water because there is a decrease in entropy during the dissolution process.

d. Solid calcium chloride must dissolve exothermically in water because there is a decrease in entropy during the dissolution process.

e. The dissolution of calcium chloride could be either endothermic or exothermic because there is an increase in entropy during the dissolution process.

6. Solid iodine would dissolve best in:

a. H₂O

b. NH₃

c. SO₂

d. CO₂

e. HCl

7. Liquid NH₃ would be a good solvent for

a. ionic compounds

b. polar compounds

c. nonpolar compounds

d. ionic and polar compounds

e. all of the above

8. The solubility of a gas in a liquid increases with

a. a decrease in pressure

b. a decrease in temperature

c. an increase in temperature

d. an increase in the stirring of the liquid

e. none of the above

9. Stirring a liquid while dissolving a solid

a. increases the solubility of the solid

b. increases the rate at which the solid dissolves

c. decreases the solubility of the solid

d. decreases the rate at which the solid dissolves

e. has no effect on the solubility or the rate of dissolution

10. The solubility of a solid in a liquid increases with

a. an increase in temperature

b. a decrease in pressure (temperature has no effect)

c. a decrease in temperature

d. an decrease in the temperature and the pressure

e. none of the above

11. In trying to dissolve a solid in water, making the size of the crystals smaller will:

a. allow you to dissolve more solid, but will not affect the rate at which the solid dissolves

b. not affect either the amount of solid that dissolves nor the rate at which it dissolves

c. increase both the amount that you are able to dissolve and the rate at which it dissolves

d. decrease the rate at which the solid dissolves, but will increase the amount that eventually dissolves

e. increase the rate at which the solid dissolves, but will not affect the amount that you are able to dissolve

12. Which would produce the largest number of particles when dissolved in water?

a. 1 mole of NaCl

b. 1 mole of C₂H₅OH

c. 1 mole of NH₄NO₃

d. 1 mole of K₂SO₄

e. 1 mole of KOH

13. C₈H₁₈ would be a good solvent for:

a. ionic compounds

b. polar compounds

c. nonpolar compounds

d. ionic and polar compounds

e. all of the above

14. Increasing the concentration of a solute in a liquid

a. lowers the boiling point and the freezing point of the liquid

b. increases the boiling point and the freezing point of the liquid

c. increases the boiling point and lowers the freezing point of the liquid

d. lowers the boiling point and increases the freezing point of the liquid

e. increases the boiling point but does not affect the freezing point of a liquid

15. Which of the following has the highest boiling point?

a. pure water

b. 0.20 M C₆H₁₂O₆

c. 0.20 M NaCl

d. 0.20 M C₂H₅OH

e. 0.20 M Na₂SO₄

16. Compared to a 0.5 Molar NaCl solution, a 1.0 Molar NaCl solution would have:

a. a lower vapor pressure and a lower boiling point

b. a higher vapor pressure and a higher boiling point

c. a lower vapor pressure and a higher boiling point

d. a higher vapor pressure and a lower boiling point

e. the same vapor pressure and boiling point

17. Compared to a 0.5 Molar NaCl solution, a 1.0 Molar glucose solution would have:

a. a lower vapor pressure and a lower boiling point

b. a higher vapor pressure and a higher boiling point

c. a lower vapor pressure and a higher boiling point

d. a higher vapor pressure and a lower boiling point

e. the same vapor pressure and boiling point

18. Concentrated nitric acid is 70.0% HNO ₃ and has a density of 1.42 g/ml. Describe how you would make 250.0 mL of 8.00 M HNO ₃ from concentrated nitric acid. (10 pts.)

19. Describe how you would make a 600.0 ml of a 22.0% NaCl solution using solid NaCl, a centigram balance, a graduated cylinder, and distilled water. (5 pts.)

20. What is the boiling point of a solution made by dissolving 160.0 g of zinc chloride into 80.0 ml of water? (10 pts.)

21. Describe how you would make 500.0 ml of a 0.750 M NaCl solution using solid NaCl, a centigram balance, a graduated cylinder, and distilled water. (5 pts.)

22. How many grams of sodium carbonate would have to be dissolved into 65.0 ml of distilled water to give the resulting solution a freezing point of -4.50 ^oC ? (10 pts.)

23. What would be the vapor pressure of the solution described in problem 22 at 40.0 ^oC ? (9 pts.)

Vapor Pressure of Ice and Water

T v.p. T v.p. T v.p.

(^oC) (torr) (^oC) (torr) (^oC) (torr)

-10 1.95 18 15.5 80 355.1

-5 3.0 19 16.5 90 525.8

-2 3.9 20 17.5 95 633.9

-1 4.2 21 18.7 96 657.6

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