CHM 2046 Module 8II Chapter 14

Sample Multiple Choice Test#1

Based on Kotz 5^th Edition

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1. The molality of a solution is

a.	moles of solute per liter of solution.
b.	moles of solute per mole of solvent.
c.	moles of solute per liter of solvent.
d.	moles of solute per kilogram of solvent.
e.	moles of solute per kilogram of solution.

2. If 0.100 mole of naphthalene is dissolved in 100. g of benzene (C₆H₆), the molality is

a.	0.100.
b.	0.900.
c.	1.00.
d.	1.28.
e.	12.8.

3. What is the mole fraction methanol, CH₃OH, in an ethanol, C₂H₅OH, solution that is 60.0% ethanol by mass?

a.	0.40
b.	0.46
c.	0.49
d.	0.54
e.	0.60

4. A solution is prepared by dissolving 0.500 mole of Al₂(SO₄)₃·18 H₂O in 838 g of water. The water of hydration becomes part of the solvent. In terms of the anhydrous salt (Al₂(SO₄)₃), the solution has the concentration

a.	0.500 m.
b.	0.600 m.
c.	0.500 M.
d.	0.600 M.
e.	0.400 m.

5. If 32.0 g of NaCl is dissolved in 350. g of H₂O, what is the percent by weight (by mass) of NaCl in the solution?

a.	0.0838%
b.	0.0914%
c.	10.7%
d.	9.14%
e.	8.38%

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6. A water sample contains 0.35 mg of arsenic in 275 g of water. The concentration of arsenic in ppm is

a.	1.3.
b.	2.3.
c.	3.5.
d.	7.6.
e.	23.

7. Calculate the mole fraction of urea (CO(NH₂)₂) that results from mixing 12.0 g of urea with 32.0 g of methanol (CH₃OH).

a.	0.125
b.	0.167
c.	0.375
d.	0.625
e.	0.833

8. Miscible liquids

a.	are polar.
b.	are nonpolar.
c.	are stable.
d.	are unstable.
e.	dissolve in each other.

9. What is the molarity of 20.0% nitric acid solution, HNO₃(aq) if the density of the solution is 1.12 g/cm³?

a.	3.56 M
b.	3.89 M
c.	4.21 M
d.	4.48 M
e.	4.84 M

10. If the dissolution of an ionic solid in water in endothermic, then it can be concluded that

a.	the solubility of the solid will increase with increasing temperature.
b.	DH is negative.
c.	the solution process releases heat.
d.	the hydration energy exceeds the lattice energy.
e.	the solubility of the solid is independent of the temperature.

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11. Which of the following pairs of liquids are miscible with each other?

a.	1 only
b.	2 only
c.	3 only
d.	1 and 2 only
e.	1, 2, and 3

12. All of the following affect the solubility of gases in solvents EXCEPT

a.	nature of the gas.
b.	nature of the solvent.
c.	pressure of the gas.
d.	temperature.
e.	atmospheric pressure.

13. If the pressure of a gas over a liquid decreases, the amount of gas dissolved in the liquid will

a.	increase.
b.	decrease.
c.	remain the same.
d.	depend on the polarity of the solvent.
e.	depend on the polarity of the gas.

14. All of the following are colligative properties of a solution EXCEPT

a.	freezing point depression.
b.	boiling point elevation.
c.	vapor pressure lowering.
d.	osmotic pressure.
e.	solute solubility.

15. The vapor pressure of a solution containing a nonvolatile solute is directly proportional to the

a.	mole fraction of solvent.
b.	mole fraction of solute.
c.	molality of the solvent.
d.	molality of the solute.
e.	osmotic pressure of the solute.

16. Consider that an ideal solution is formed from a mixture of the nonvolatile solute, urea (CO(NH₂)₂), and methanol (CH₃OH). The vapor pressure of pure methanol at 20°C is 89 mm Hg. Calculate the mole fraction of urea that is obtained from mixing 6.0 g of urea with 32.0 g of methanol. Top of Form

a.	0.091
b.	0.10
c.	0.16
d.	0.84
e.	0.91

17. Consider that an ideal solution is formed from a mixture of the nonvolatile solute, urea (CO(NH₂)_2,), and methanol (CH₃OH). The vapor pressure of pure methanol at 20?C is 89 mm Hg. Calculate the vapor pressure of the methanol solution in problem No. 16.

a.	8.1 mm Hg
b.	8.9 mm Hg
c.	14 mm Hg
d.	75 mm Hg
e.	81 mm Hg

18. Consider that an ideal solution is formed from a mixture of the nonvolatile solute, urea (CO(NH₂)₂), and methanol (CH₃OH). The vapor pressure of pure methanol at 20°C is 89 mm Hg. Calculate the vapor pressure-lowering for the methanol solution in problem No. 16.

a.	6.0 mm Hg
b.	8.0 mm Hg
c.	14 mm Hg
d.	75 mm Hg
e.	81 mm Hg

19. The freezing point of a 0.025 m solution of formaldehyde (CH₂O) in water would be (K_f for water is -1.86°C/m).

a.	-1.86°C
b.	-0.046°C
c.	0.046°C
d.	0.093°C
e.	-0.093°C

20. The freezing point of an aqueous solution of a nonelectrolyte is -0.23°C. The molality of this solution is (K_f(H₂O) = -1.86°C/m)

a.	0.12.
b.	0.25.
c.	0.45.
d.	0.51.
e.	1.86.

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21. A compound containing boron, nitrogen, and hydrogen analyzes 40.3% B, 52.2% N, and 7.5% H. A 3.562 g sample of this compound was dissolved in 50.00 g of benzene producing a solution freezing at 1.3°C. K_f for benzene is -5.12°C/molal. Pure benzene has a freezing point of 5.48°C. Determine the empirical formula of the compound from the percentage composition. The empirical weight of the B, N, H compound is

a.	25.8.
b.	26.8.
c.	50.6.
d.	51.6.
e.	106.

22. A compound containing boron, nitrogen, and hydrogen analyzes 40.3% B, 52.2% N, and 7.5% H. A 3.562 g sample of this compound was dissolved in 50.00 g of benzene producing a solution freezing at 1.3°C. K_f for benzene is -5.12°C/molal. Pure benzene has a freezing point of 5.48°C. The molality of the benzene solution is

a.	0.071.
b.	0.24.
c.	0.70.
d.	0.82.
e.	1.07

23. A compound containing boron, nitrogen, and hydrogen analyzes 40.3% B, 52.2% N, and 7.5% H. A 3.562 g sample of this compound was dissolved in 50.00 g of benzene producing a solution freezing at 1.3°C. K_f for benzene is -5.12°C/molal. Pure benzene has a freezing point of 5.48°C. The experimental molecular weight for the compound is

a.	67.
b.	87.
c.	102.
d.	106.
e.	297.

24. A compound containing boron, nitrogen, and hydrogen analyzes 40.3% B, 52.2% N, and 7.5% H. A 3.562 g sample of this compound was dissolved in 50.00 g of benzene producing a solution freezing at 1.3°C. K_f for benzene is -5.12°C/molal. Pure benzene has a freezing point of 5.48°C. The molecular formula for the compound is

a.	B2N2H.
b.	B4N4H2.
c.	BNH2.
d.	B3N3H6.
e.	B4N4H8.

25. For a 0.001 molal solution of Al₂(SO₄)₃, the van't Hoff factor, i, would be about

a.	1
b.	2
c.	3
d.	4
e.	5

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