Test Bank General Chemistry, 10th edition 19
63. What is the mole fraction of urea, CH4N2O, in an aqueous solution that is 36% urea by
mass?
A)
0.14
B)
0.86
C)
0.36
D)
0.55
E)
0.65
64. What is the mole fraction of urea, CO(NH2)2, in a solution prepared by dissolving 6.8 g of
urea in 33.5 g of methanol, CH3OH?
A)
0.83
B)
0.17
C)
0.098
D)
0.90
E)
0.28
65. What is the mole fraction of toluene in a solution of 3.4 mol of benzene and 5.2 mol of
toluene?
A)
0.64
B)
0.54
C)
0.60
D)
0.24
E)
0.40
66. What is the mole fraction of water in a solution that contains 6.8 mol of ethanol (C2H5OH)
and 1.2 mol of water?
A)
0.15
B)
0.07
C)
0.57
D)
0.18
E)
0.85
67. What is the mole fraction of water in a water–ethanol solution that is 46.0% water by mass?
(Ethanol is C2H5OH.)
A)
0.28
B)
0.31
C)
0.25
D)
0.69
E)
0.54
68. What is the mole fraction of urea in a solution that contains 2.1 mol of urea and 4.4 mol of
water?
A)
0.77
B)
0.32
C)
0.42
D)
0.52
E)
0.68
69. Which way of expressing concentration is used to relate the vapor pressure of a solution to
the amount of nonvolatile solute dissolved in the solution?
A)
mole fraction
B)
molarity
C)
osmotic pressure
D)
mass percent
E)
molality
Test Bank General Chemistry, 10th edition 21
70. When 1 mol of a nonvolatile nonelectrolyte is dissolved in 3 mol of a solvent, the vapor
pressure of the solution compared with that of the pure solvent is
A)
1/4.
B)
4/5.
C)
1/2.
D)
1/5.
E)
3/4.
71. What is the vapor pressure at 20°C of an ideal solution prepared by the addition of 8.87 g of
the nonvolatile solute urea, CO(NH2)2, to 57.6 g of methanol, CH3OH? The vapor pressure
of pure methanol at 20°C is 89.0 mmHg.
A)
6.75 mmHg
B)
69.1 mmHg
C)
77.1 mmHg
D)
82.2 mmHg
E)
19.9 mmHg
72. What is the vapor pressure at 75°C of an aqueous solution prepared by the addition of 64.3 g
of the nonvolatile solute urea, CO(NH2)2, to 174 g of water? The vapor pressure of pure
water at 75°C is 290. mmHg.
A)
133 mmHg
B)
28.9 mmHg
C)
167 mmHg
D)
261 mmHg
E)
212 mmHg
73. Benzene, C6H6, and toluene, C6H5CH3, form ideal solutions. At 35°C the vapor pressure of
benzene is 160. torr and that of toluene is 50.0 torr. In an experiment, 67.6 g of benzene and
86.7 g of toluene are placed in a closed container at 35°C. At equilibrium, what is the
partial vapor pressure of toluene?
A)
108 torr
B)
83.3 torr
C)
24.0 torr
D)
76.7 torr
E)
26.0 torr
74. Benzene, C6H6, and toluene, C6H5CH3, form ideal solutions. At 35°C the vapor pressure of
benzene is 160. torr and that of toluene is 50.0 torr. In an experiment, 3.6 mol of benzene
and 5.5 mol of toluene are placed in a closed container at 35°C and allowed to come to
equilibrium. What is the mole fraction of toluene in the vapor phase?
A)
0.52
B)
0.68
C)
0.32
D)
0.14
E)
0.60
75. A liquid–liquid solution is called an ideal solution if
I.
it obeys PV = nRT.
II.
it obeys Raoult’s law.
III.
solute–solute, solvent–solvent, and solute–solvent interactions are very similar.
IV.
solute–solute, solvent–solvent, and solute–solvent interactions are quite
different.
A)
I, III, IV
B)
I, II, III
C)
II, III only
D)
I, II, IV
E)
II, IV only
76. A solution of two liquids, A and B, shows negative deviation from Raoult’s law. This means
that
A)
the two liquids have a positive heat of solution.
B)
molecules of A interact more strongly with B than A molecules interact with A or
B molecules interact with B.
C)
molecules of A interact strongly with other A-type molecules.
D)
molecules of A interact weakly, if at all, with B molecules.
E)
molecules of A hinder the strong interaction between B molecules.
77. A solution of CF3H in H2CO is most likely to
A)
be ideal.
B)
not be ideal, but the deviations cannot be predicted.
C)
show negative deviations from Raoult’s law.
D)
obey Raoult’s law.
E)
show positive deviations from Raoult’s law.
78. The fact that the boiling point of a pure solvent is lower than the boiling point of a solution
of the same solvent is a direct consequence of the
A)
freezing-point depression of the solution.
B)
vapor pressure of the solution being higher than the vapor pressure of the pure
solvent.
C)
osmotic pressure of the solvent being lower than the osmotic pressure of the
solution.
D)
vapor pressure of the solution being lower than the vapor pressure of the pure
solvent.
E)
osmotic pressure of the solvent being higher than the osmotic pressure of the
solution.
79. A solute added to a solvent raises the boiling point of the solution because
A)
the temperature to cause boiling must be great enough to boil not only the solvent
but also the solute.
B)
the solute particles raise the solvent’s vapor pressure, thus requiring a higher
temperature to cause boiling.
C)
the solute increases the volume of the solution, and an increase in volume requires
an increase in the temperature to reach the boiling point (derived from PV = nRT).
D)
the solute particles lower the solvent’s vapor pressure, thus requiring a higher
temperature to cause boiling.
E)
two of these explanations are correct.
Test Bank General Chemistry, 10th edition 24
80. What is the freezing point of a 0.24 m solution of glucose, C6H12O6, in water? (Kf for water
is 1.858°C/m.)
A)
0.22°C
B)
0.45°C
C)
–0.45°C
D)
–0.22°C
E)
–0.89°C
81. What is the boiling-point change for a solution containing 0.432 mol of naphthalene (a
nonvolatile, nonionizing compound) in 250. g of liquid benzene? (Kb = 2.53°C/m for
benzene)
A)
4.37 °C
B)
5.86 °C
C)
0.273 °C
D)
1.46 °C
E)
1.093 °C
82. Substance A has a greater molar mass than substance B. If 50 g of substance A are dissolved
in 250 g of water in one beaker, and 50 g of substance B are dissolved in 250 g of water in
another beaker, then
A)
the vapor pressure of solution A will be lower than the vapor pressure of
solution B.
B)
the solution of A will freeze at a lower temperature than the solution of B.
C)
the two solutions will have the same vapor pressure.
D)
the boiling point of solution A will be lower than the boiling point of solution B.
E)
the solution of A will have a higher osmotic pressure than the solution of B.
83. A solution consisting of 0.228 mol of methylbenzene, C6H5CH3, in 255 g of nitrobenzene,
C6H5NO2, freezes at –0.3°C. Pure nitrobenzene freezes at 6.0°C. What is the freezing-point
depression constant of nitrobenzene?
A)
1.1°C/m
B)
27°C/m
C)
14.0°C/m
D)
3.5°C/m
E)
7.0°C/m
84. What is the mass percent of ethylene glycol (HOCH2CH2OH) in a solution of ethylene
glycol in water that has a freezing point of –19.2°C? (Kf for water is 1.858°C/m.)
A)
99.8%
B)
39.1%
C)
64.1%
D)
60.1%
E)
10.3%
85. Which of the following methods cannot be used to determine the molar mass of a
nonelectrolyte?
A)
measurement of the freezing-point depression of a solution of the compound
B)
measurement of the boiling-point elevation of a solution of the compound
C)
measurement of the pressure, temperature, volume, and mass of the compound in
the gaseous state
D)
measurement of the x-ray diffraction of a pure crystal of the compound
E)
measurement of the osmotic pressure of a solution of the compound
86. Trimellitic acid is an organic acid that has a composition of 51.44% C, 2.88% H, and
45.68% O by mass. A 5.02-g sample of trimellitic acid dissolved in 20 g of acetone,
CH3COCH3, has a boiling point of 58.24°C. What is the molecular formula of trimellitic
acid? (Kb for acetone is 1.71°C/m, and pure acetone has a boiling point of 56.20°C.)
A)
CH2O
B)
C9H6O6
C)
C3HO2
D)
C18HO16
E)
C6H2O4
87. When a 28.4-g sample of an unknown compound is dissolved in 500. g of benzene, the
freezing point of the resulting solution is 3.77°C. The freezing point of pure benzene is
5.48°C, and Kf for benzene is 5.12°C/m. Calculate the molar mass of the unknown
compound.
A)
145 g/mol
B)
170. g/mol
C)
85.0 g/mol
D)
340 g/mol
E)
16.6 g/mol
88. Thyroxine, an important hormone that controls the rate of metabolism in the body, can be
isolated from the thyroid gland. If 0.453 g of thyroxine is dissolved in 10.0 g of benzene, the
freezing point of the solution could be measured as 5.144°C. Pure benzene freezes at
5.444°C and has a value for the molal freezing-point-depression constant of Kf of 5.12°C/m.
What is the approximate molar mass of thyroxine?
A)
773 g/mol
B)
7.73 g/mol
C)
7.73 105 g/mol
D)
42.6 g/mol
E)
11.3 g/mol
89. If a 18.0-g sample of a nonelectrolyte is dissolved in 112.0 g of water, the resulting solution
will freeze at –0.94°C. What is the molar mass of the nonelectrolyte? (Kf for water is
1.858°C/m.)
A)
77 g/mol
B)
0.32 g/mol
C)
550 g/mol
D)
280 g/mol
E)
320 g/mol
Test Bank General Chemistry, 10th edition 27
90. What is the molar mass of an aromatic hydrocarbon if 0.85 g of the compound depresses the
freezing point of 128 g of benzene by 0.37°C? (Kf for benzene is 5.12°C/m.)
A)
35 g/mol
B)
150 g/mol
C)
93 g/mol 92
D)
2100 g/mol
E)
140 g/mol
91. Which of the following will cause the calculated molar mass of a compound determined by
the freezing-point-depression method to be greater than the true molar mass?
A)
When the solute was added, some was spilled on the lab bench.
B)
Water gets into the solvent after the freezing point of the pure solvent is
determined.
C)
Some of the solute molecules break apart.
D)
The mass of solvent is smaller than that determined from the weighing.
E)
all of the above
92. A compound containing carbon and nitrogen has a composition of 46.16% carbon and
53.84% nitrogen by mass. A solution prepared by dissolving 1.542 g of this compound in
30.00 g of carbon tetrachloride, CCl4, produces a solution that boils at 81.69°C. What is the
molecular formula of the compound? (Kb for CCl4 is 5.03°C/m, and pure CCl4 has a
freezing point of 76.72°C.)
A)
C2N2
B)
CN2
C)
C3N3
D)
CN
E)
C2N4
93. A compound containing sulfur, nitrogen, and hydrogen has a composition of 86.6% sulfur,
12.6% nitrogen, and 0.91% hydrogen by mass. A solution prepared by dissolving 2.072 g of
this compound in 35.00 g of bromoform, CHBr3, produces a solution that freezes at 3.97°C.
What is the molecular formula of the compound? (Kf for bromoform is 14.4°C/m, and pure
bromoform has a freezing point of 7.8°C.)
Test Bank General Chemistry, 10th edition 28
A)
SNH
B)
S3N2H2
C)
S6N2H2
D)
S3NH
E)
S2N2H2
94. A cucumber is placed in a concentrated salt solution. What is most likely to happen?
A)
Water will flow from the solution to the cucumber.
B)
No change will occur.
C)
Salt will flow into the cucumber.
D)
Salt will precipitate out.
E)
Water will flow from the cucumber to the solution.
95. A red blood cell placed in pure water will swell because
A)
the osmotic pressure is greater in the water than in the cell.
B)
the osmotic pressure is the same in the cell and the water.
C)
the osmotic pressure is greater in the cell than in the water.
D)
water moves from a higher osmotic pressure to a lower osmotic pressure.
E)
the vapor pressure of the water in the cell is greater than the vapor pressure of pure
water.
96. What is reverse osmosis?
A)
the application, to a dilute solution, of a pressure that is greater than the osmotic
pressure, such that solvent flows from the concentrated solution to the dilute
solution
B)
the application, to a dilute solution, of a pressure that is greater than the osmotic
pressure, such that solute flows from the concentrated solution to the dilute
solution
C)
the application, to a concentrated solution, of a pressure that is greater than the
osmotic pressure, such that solute flows from the concentrated solution to the
dilute solution
Test Bank General Chemistry, 10th edition 29
D)
the application, to a concentrated solution, of a pressure that is greater than the
osmotic pressure, such that solvent flows from the concentrated solution to the
dilute solution
E)
the application, to a concentrated solution, of a pressure that is greater than the
osmotic pressure, such that solvent flows from the dilute solution to the
concentrated solution
97. A solution of water and a nonvolatile, nonionizing compound is placed in a tube with a
semipermeable membrane on one side. The tube is placed in a beaker of pure water. What
initial net effect will occur?
A)
Nothing will move through the membrane either way.
B)
Water will flow from the beaker to the tube.
C)
Water will flow from the tube to the beaker.
D)
Equilibrium will be immediately established.
E)
The compound will pass through the membrane into the solution.
98. Determine the osmotic pressure of a solution that contains 0.014 g of a hydrocarbon solute
(molar mass = 340 g/mol) dissolved in benzene to make a 350-mL solution. The
temperature is 20.0°C.
A)
0.9 torr
B)
2.0 torr
C)
0.14 torr
D)
0.7 torr
E)
2.1 torr
99. A 2.4-g sample of a small protein having a molecular weight of 62,000 g/mol is dissolved in
59.6 mL of water at 29°C. What is the osmotic pressure of the solution?
(R = 0.0821 L · atm/(K · mol))
A)
12 mmHg
B)
760 mmHg
C)
1.2 mmHg
D)
47,000 mmHg
E)
0.016 mmHg
100. Osmotic pressure is
A)
inversely proportional to mass fraction.
B)
directly proportional to lattice energy.
C)
inversely proportional to molality.
D)
inversely proportional to mole fraction.
E)
directly proportional to molarity.
101. Calculate the molecular weight of a small protein if a 0.24-g sample dissolved in 108 mL of
water has an osmotic pressure of 9.5 mmHg at 22°C. (R = 0.0821 L · atm/(K · mol))
A)
3.2 102 g/mol
B)
4.3 103 g/mol
C)
5.7 g/mol
D)
1.8 102 g/mol
E)
5.7 10–3 g/mol
102. To determine the molar mass of a small protein in the range of 20,000–40,000 g/mol, it
would be best to measure
A)
the freezing point of the solvent and of the solution and the weight of the solute
and solvent.
B)
the boiling point of the solvent and of the solution and the weight of the solute and
solvent.
C)
the vapor pressure of the solvent and of the solution and the weight of the solute
and solvent.
D)
the osmotic pressure of the solution and the weight of the solute and solvent.
E)
the density of the protein and to make x-ray measurements.
103. For a dilute solution of (NH4)3PO4, the van’t Hoff factor (i) would be approximately
A)
4.
B)
2.
C)
3.
D)
1.
E)
5.
104. For a dilute solution of FeCl3, the van’t Hoff factor (i) would be approximately
A)
4.
B)
2.
C)
3.
D)
1.
E)
5.
105. Based on the formulas of the following solutes, which compound would have the smallest
van’t Hoff factor (i)?
A)
Ca(NO3)2(aq)
B)
K2SO4(aq)
C)
Th(SO4)2(aq)
D)
Al2(SO4)3(aq)
E)
MgSO4(aq)
106. Which of the following solutes in aqueous solution would be expected to exhibit the
smallest freezing-point lowering (assuming ideal behavior)?
A)
0.1 m NaCl
B)
0.2 m CH3COOH
C)
0.05 m Al2(SO4)3
D)
0.1 m MgCl2
E)
0.25 m NH3
107. Which of the following solutions would have the highest osmotic pressure?
A)
0.15 M MgBr2
B)
0.15 M NaCl
C)
0.20 M C12H22O11
D)
0.20 M C6H12O6
E)
0.20 M CH3OH
108. What is the freezing point of an aqueous 1.66 m CaCl2 solution? (Kf for water is 1.858°C/m.)
A)
9.3°C
B)
3.1°C
C)
–9.3°C
D)
0.0°C
E)
–3.1°C
109. Which of the following amounts of solute, dissolved in 1.0 kg of water, creates a solution
with the lowest freezing temperature? (assuming ideal behavior)
A)
0.0015 mol of sulfuric acid, H2SO4
B)
0.0015 mol of H2SO3
C)
0.0030 mol of ethanol, C2H5OH
D)
0.0030 mol of methanol, CH3OH
E)
0.0015 mol of sucrose, C12H22O11
110. Which of the following solutes, dissolved in 1.0 kg of water, creates a solution that boils at
the highest temperature?
A)
0.010 mol H3PO4
B)
0.010 mol HClO4
C)
0.010 mol H2SO4
D)
0.010 mol HCl
E)
0.010 mol HF
111. Which of the following solutes, dissolved in 1000 g of water, would provide a solution with
the lowest freezing point?
A)
0.030 mol of barium chloride, BaCl2
B)
0.030 mol of urea, CO(NH2)2
C)
0.030 mol of calcium sulfate, CaSO4
D)
0.030 mol of acetic acid, CH3COOH
E)
0.030 mol of ammonium nitrate, NH4NO3
112. Which of the following solutions has the lowest osmotic pressure?
A)
0.10 M Al(NO3)3
B)
0.20 M C6H12O6
C)
0.15 M Ba(NO3)2
D)
0.10 M CaCl2
E)
0.15 M Na2S
113. At 37°C, what is the osmotic pressure of a 0.59% NaCl by weight aqueous solution?
Assume the density of the solution is 1.0 g/mL. (R = 0.0821 L · atm/(K · mol))
A)
0.26 atm
B)
2.6 atm
C)
3.0 102 atm
D)
5.1 atm
E)
0.61 atm
114. For which of the following aqueous solutions would one expect to have the largest van’t
Hoff factor (i)?
A)
0.400 m K2SO4
B)
0.400 m NaCl
C)
0.400 m C6H12O6 (glucose)
D)
0.040 m K2SO4
E)
0.040 m NaCl
115. The molal boiling-point constant for water is 0.51°C/molal. The boiling point of a 1.00 m
solution of Ca(NO3)2 should be increased by
A)
exactly 1.53°C.
B)
exactly 1.02°C.
C)
somewhat less than 1.02°C.
D)
exactly 0.51°C.
E)
somewhat less than 1.53°C.
116. What type of colloid is formed when a liquid is dispersed in a gas?
A)
foam
B)
emulsion
C)
aerosol
D)
sol
E)
gel
117. What type of colloid is formed when a gas is dispersed in a solid?
A)
foam
B)
aerosol
C)
sol
D)
emulsion
E)
gel
118. What type of colloid is formed when a liquid is dispersed in a solid?
A)
emulsion
B)
gel
C)
sol
D)
foam
E)
aerosol
119. What type of colloid is formed when a solid is dispersed in a liquid?
A)
emulsion
B)
gel
C)
aerosol
D)
sol
E)
foam
120. When a liquid is dispersed in another liquid, the resulting colloid is called a(n)
A)
emulsion.
B)
sol.
C)
foam.
D)
aerosol.
E)
gel.
121. A suspension of silver particles in water is most likely to form what type of colloid?
A)
aerosol
B)
micelle
C)
hydrophobic colloid
D)
association colloid
E)
hydrophilic colloid
122. Which of the following statements describes the process of coagulation?
A)
The dispersed phase of an association colloid aggregates and forms a hydrophilic
colloid.
B)
The continuous phase of a colloid aggregates and separates from the dispersed
phase.
C)
The dispersed phase of an association colloid aggregates and forms a hydrophobic
colloid.
D)
The dispersed phase of a colloid aggregates and separates from the continuous
phase.
E)
The dispersed phase of an association colloid aggregates and forms a micelle.
123. A suspension of sodium dodecanoate, CH3(CH2)10COONa, in water is most likely to form
what type of colloid?
A)
hydrophilic colloid
B)
association colloid
C)
emulsion
D)
aerosol
E)
hydrophobic colloid
124. Synthetic detergent dispersed in water is an example of a(n)
A)
micelle.
B)
hydrophilic colloid.
C)
coagulant.
D)
hydrophobic colloid.
E)
association colloid.