A
20.0-g sample of methyl alcohol (CH3OH,
molar mass = 32.0 g/mol) was dissolved in 30.0 g of water. The mole fraction
of CH3OH is:
A.
0.400
B.
0.625
C.
0.728
D.
0.667
E.
none of these
2.
A solution of hydrogen peroxide is 30.0% H2O2 by mass and has a density of 1.11 g/cm3. The molarity of the solution is:
A.
7.94 M
B.
8.82 M
C.
9.79 M
D.
0.980 M
E.
none of these
3.
Calculate the molality of C2H5OH in a water solution that is prepared by mixing 50.0 mL of C2H5OH with 100.0 mL of H2O at 20°C. The density of the C2H5OH is 0.789 g/mL at 20°C.
A.
0.086 m
B.
0.094 m
C.
1.24 m
D.
8.56 m
E.
none of these
4.
How many milliliters of 18.4 M H2SO4 are needed to prepare 600.0 mL of 0.10 M H2SO4?
A.
1.8 mL
B.
2.7 mL
C.
3.3 mL
D.
4.0 mL
E.
4.6 mL
5.
Which of the following concentration measures will change in value as the temperature of a solution changes?
A.
mass percent
B.
mole fraction
C.
molality
D.
molarity
E.
all of these
6.
What is the mole percent of ethanol (C2H5OH) in 180 proof vodka, which consists of 71.0 g of ethanol for every 10.0 g of water present?
A.
73.5%
B.
71.0%
C.
87.7%
D.
26.5%
E.
22.1%
7.
If 2.00 g of helium gas and 4.00 g of oxygen gas are mixed together what is the mole fraction of helium in the solution?
A.
0.500
B.
0.333
C.
0.800
D.
0.200
E.
0.666
8.
Concentrated nitric acid is a solution that is 70% HNO3, by mass. The density of this acid is 1.42 g/cm3. What is the molarity of this acid?
A.
0.06 M
B.
6.8 M
C.
0.16 M
D.
12.4 M
E.
15.8 M
9.
Rank the following compounds according to increasing solubility in water. I. CH3–CH2–CH2–CH3 II. CH3–CH2–O–CH2–CH3 III. CH3–CH2–OH IV. CH3–OH
A.
I
<
III
<
IV
<
II
B.
I
<
II
<
IV
<
III
C.
III
<
IV
<
II
<
I
D.
I
<
II
<
III
<
IV
E.
No order is correct.
10.
Which of the following favors the solubility of an ionic solid in a liquid solvent?
A.
a large magnitude of the solvation energy of the ions
B.
a small magnitude of the lattice energy of the solute
C.
a large polarity of the solvent
D.
all of these
E.
none of these
11.
A correct statement of Henry's law is:
A.
the concentration of a gas in solution is inversely proportional to temperature.
B.
the concentration of a gas in solution is directly proportional to the mole fraction of solvent.
C.
the concentration of a gas in solution is independent of pressure.
D.
the concentration of a gas in a solution is inversely proportional to pressure.
E.
none of these
12.
The solubility of O2 in water is 0.590 g/L at an oxygen pressure of 15 atm. What is the Henry's law constant for O2 (in units of L-atm/mol)?
A.
3.93 ´ 10–3
B.
1.23 ´ 10–3
C.
8.14 ´ 102
D.
1.26
E.
None of these are within 5% of the correct answer.
13.
At a given temperature, you have a mixture of benzene (vapor pressure of pure benzene = 745 torr) and toluene (vapor pressure of pure toluene = 290. torr). The mole fraction of benzene in the solution is 0.590. Assuming ideal behavior, calculate the mole fraction of toluene in the vapor above the solution.
A.
0.213
B.
0.778
C.
0.641
D.
0.359
E.
0.590
14.
At 40°C, heptane has a vapor pressure of 92.0 torr and octane has a vapor pressure of 31.2 torr. Assuming ideal behavior, what is the vapor pressure of a solution that contains twice as many moles of heptane as octane?
A.
61.6 torr
B.
51.5 torr
C.
71.7 torr
D.
76.8 torr
E.
none of these
15.
A solution is prepared from 31.4 g of a nonvolatile, nondissociating solute and 85.0 g of water. The vapor pressure of the solution at 60°C is (142 torr). The vapor pressure of water at 60°C is 150. torr. What is the molar mass of the solute?
Answer:
16.
A solution contains 1 mole of liquid A and 3 mol of liquid B. This solution has a vapor pressure of 314 torr at 25°C. At 25°C, liquid A has a vapor pressure of 265 torr and liquid B has a vapor pressure of 355 torr. Which of the following is true?
A.
This solution exhibits a positive deviation from Raoult's Law.
B.
This solution exhibits a negative deviation from Raoult's Law.
C.
This solution is ideal.
17.
You have a 10.40-g mixture of table sugar (C12H22O11) and table salt (NaCl). When this mixture is dissolved in 150. g of water, the freezing point is found to be –2.24°C. Calculate the percent by mass of sugar in the original mixture.
A.
39.0%
B.
43.8%
C.
56.2%
D.
61.0%
E.
none of these
18.
A 5.50-gram sample of a compound as dissolved in 250. grams of benzene. The freezing point of this solution is 1.02°C below that of pure benzene. What is the molar mass of this compound? (Note:Kf for benzene = 5.12°C/m.)
A.
22.0 g/mol
B.
110. g/mol
C.
220. g/mol
D.
44.0 g/mol
E.
none of these
19.
What is the boiling point change for a solution containing 0.328 moles of naphthalene (a nonvolatile, nonionizing compound) in 250. g of liquid benzene? (Kb = 2.53°C/m for benzene)
A.
3.32°C
B.
7.41°C
C.
1.93°C
D.
4.31°C
E.
10.7°C
20.
Thyroxine, an important hormone that controls the rate of metabolism in the body, can be isolated from the thyroid gland. If 0.455 g of thyroxine is dissolved in 10.0 g of benzene, the freezing point of the solution is 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 molar mass of thyroxine?
A.
777,000 g/mol
B.
777 g/mol
C.
2330 g/mol
D.
285 g/mol
E.
3760 g/mol
21.
To calculate the freezing point of an ideal dilute solution of a single, nondissociating solute of a solvent, the minimum information one must know is:
A.
the molality (of the solute).
B.
the molality (of the solute) and the freezing point depression constant of the solvent.
C.
the same quantities as in b plus the freezing point of the pure solvent.
D.
all of the quantities in c plus the molecular weight of the solute.
E.
all of the quantities in c plus the weight of the solvent.
22.
Determine the change in boiling point for 300.0 g of carbon disulfide (Kb = 2.34°C kg/mol) if 35 g of a nonvolatile, nonionizing compound is dissolved in it. The molar mass of the compound is 70.0 g/mol and the boiling point of the pure carbon disulfide is 46.2°C.
A.
13.4°C
B.
10.9°C
C.
7.7°C
D.
15.6°C
E.
3.9°C
23.
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.
Water gets into the solvent after the freezing point of the pure solvent is determined.
B.
Some of the solute molecules break apart.
C.
The mass of solvent is smaller than determined from the weighing.
D.
While adding the solute, some was spilled on the lab bench.
E.
all of these
24.
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 lower the solvent's vapor pressure, thus requiring a higher temperature to cause boiling.
C.
the solute particles raise the solvent's vapor pressure, thus requiring a higher temperature to cause boiling.
D.
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).
E.
two of these are correct.
25.
A cucumber is placed in a concentrated salt solution. What will most likely happen?
A.
Water will flow from the cucumber to the solution.
B.
Water will flow from the solution to the cucumber.
C.
Salt will flow into the cucumber.
D.
Salt will precipitate out.
E.
No change will occur.
26.
Polyethylene is a synthetic polymer or plastic with many uses. 1.40 g of a polyethylene sample was dissolved in enough benzene to make 100. mL of solution, and the osmotic pressure was found to be 1.86 torr at 25°C. What is the molar mass of the polyethylene?
A.
1.06 ´ 108 g/mol
B.
1.19 ´ 104 g/mol
C.
5720 g/mol
D.
3.39 ´ 106 g/mol
E.
1.40 ´ 105 g/mol
27.
Osmotic pressure depends on all but which of the following?
A.
atmospheric pressure
B.
the molarity of the solution
C.
temperature
D.
the ratio of moles of solute to solution volume
E.
none of these
28.
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.
Water will flow from the beaker to the tube.
B.
Water will flow from the tube to the beaker.
C.
The compound will pass through the membrane into the solution.
D.
Nothing will move through the membrane either way.
E.
Equilibrium is immediately established.
29.
Determine the osmotic pressure of a solution that contains 0.025 g of a hydrocarbon solute (molar mass = 340 g/mole) dissolved in benzene to make a 350-mL solution. The temperature is 20.0°C.
A.
1.1 torr
B.
1.6 torr
C.
2.2 torr
D.
3.8 torr
E.
4.4 torr
30.
A 0.20 M solution of MgSO4 has an observed osmotic pressure of 7.8 atm at 25°C. Determine the observed van't Hoff factor for this experiment.
A.
1.2
B.
1.4
C.
1.6
D.
1.8
E.
2.0
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