21
18) The mole fraction of urea (MW = 60.0 g/mol) in a solution prepared by dissolving 16 g of urea in 39 g
of H2O is ________.
A) 0.58
B) 0.37
C) 0.13
D) 0.11
E) 9.1
19) The concentration of urea (MW = 60.0 g/mol) in a solution prepared by dissolving 16 g of urea in 39 g
of H2O is ________ molal.
A) 96
B) 6.8
C) 0.68
D) 6.3
E) 0.11
20) The molarity of urea in a solution prepared by dissolving 16 g of urea (MW = 60.0 g/mol) in 39 g of
H2O is ________ M. The density of the solution is 1.3 g/mL.
A) 0.11
B) 3.7
C) 6.8
D) 6.3
E) 0.16
21) What is the molarity of sodium chloride in solution that is 13.0% by mass sodium chloride and that
has a density of 1.10 g/mL?
A) 143
B) 2.45
C) 2.56
D) 2.23
E) 1.43 × 10-2
22) What is the molality of sodium chloride in solution that is 13.0% by mass sodium chloride and that
has a density of 1.10 g/mL?
A) 2.23
B) 1.30
C) 2.56
D) 2.03
E) 1.10
23) What is the mole fraction of sodium chloride in solution that is 13.0% by mass sodium chloride and
that has a density of 1.10 g/mL?
A) 0.0442
B) 0.0462
C) 0.223
D) 0.483
E) 0.505
24) The vapor pressure of pure ethanol at 60 °C is 0.459 atm. Raoult’s Law predicts that a solution
prepared by dissolving 10.0 mmol naphthalene (nonvolatile) in 90.0 mmol ethanol will have a vapor
pressure of ________ atm.
A) 0.498
B) 0.413
C) 0.790
D) 0.367
E) 0.0918
25) The vapor pressure of pure water at 25 °C is 23.8 torr. What is the vapor pressure (torr) of water above
a solution prepared by dissolving 18.0 g of glucose (a nonelectrolyte, MW = 180.0 g/mol) in 95.0 g of
water?
A) 24.3
B) 23.4
C) 0.451
D) 0.443
E) 23.8
26) What is the freezing point (°C) of a solution prepared by dissolving 11.3 g of Ca(NO3)2
(formula weight = 164 g/mol) in 115 g of water? The molal freezing point depression constant for water is
1.86 °C/m.
A) -3.34
B) -1.11
C) 3.34
D) 1.11
E) 0.00
27) A solution containing 10.0 g of an unknown liquid and 90.0 g water has a freezing point of -3.33 °C.
Given Kf = 1.86 °C/m for water, the molar mass of the unknown liquid is ________ g/mol.
A) 69.0
B) 333
C) 619
D) 161
E) 62.1
28) A solution containing 20.0 g of an unknown liquid and 110.0 g water has a freezing point of –1.32 °C.
Given Kf = 1.86 °C/m for water, the molar mass of the unknown liquid is ________ g/mol.
A) 256
B) 69.0
C) 333
D) 619
E) 78.1
29) A solution is prepared by dissolving 0.60 g of nicotine (a nonelectrolyte) in water to make 12 mL of
solution. The osmotic pressure of the solution is 7.55 atm at 25 °C. The molecular weight of nicotine is
________ g/mol.
A) 28
B) 43
C) 50
D) 160
E) 0.60
30) A solution is prepared by dissolving 6.00 g of an unknown nonelectrolyte in enough water to make
1.00 L of solution. The osmotic pressure of this solution is 0.750 atm at 25.0 °C. What is the molecular
weight (g/mol) of the unknown solute?
A) 16.4
B) 196
C) 110
D) 30.6
E) 5.12 × 10-3
31) An aqueous solution of a soluble compound (a nonelectrolyte) is prepared by dissolving 33.2 g of the
compound in sufficient water to form 250 mL of solution. The solution has an osmotic pressure of 1.2 atm
at 25 °C. What is the molar mass (g/mole) of the compound?
A) 1.0 × 103
B) 2.7 × 103
C) 2.3 × 102
D) 6.8 × 102
E) 28
32) Determine the freezing point (°C) of a 0.015 molal aqueous solution of MgSO4. Assume i = 2.0 for
MgSO4. The molal freezing-point-depression constant of water is 1.86 °C/m.
A) -0.056
B) -0.028
C) -0.17
D) -0.084
E) 0.000
33) A solution is prepared by dissolving 2.60 g of a strong electrolyte (formula weight = 101 g/mol) in
enough water to make 1.00 L of solution. The osmotic pressure of the solution is 1.25 atm at 25.0 °C. What
is the van’t Hoff factor (i) for the unknown solute?
A) 0
B) 0.99
C) 1.98
D) 2.98
E) 0.630
34) George is making spaghetti for dinner. He places 4.01 kg of water in a pan and brings it to a boil.
Before adding the pasta, he adds 58 g of table salt (NaCl) to the water and again brings it to a boil. The
temperature of the salty, boiling water is ________°C.
Assume a pressure of 1.00 atm and negligible evaporation of water. Kb for water is 0.52 °C/m.
A) 99.87
B) 100.26
C) 100.13
D) 99.74
E) 100.00
13.3 Algorithmic Questions
1) A saturated solution ________.
A) contains dissolved solute in equilibrium with undissolved solute
B) has the capacity to dissolve more solute
C) will rapidly precipitate if a seed crystal is added
D) contains no double bonds
E) cannot be attained
2) Which one of the following substances would be the most soluble in CCl4?
A) C4H10
B) Li2O
C) NH3
D) HCl
E) CH3CH2CH2OH
3) Which one of the following substances would be the least soluble in CCl4?
A) Na2SO4
B) C4H10
C) F2
D) HCl
E) CH3CH2CH2CH2OH
4) The Henry’s law constant for helium gas in water at 30 °C is 3.70 × 10-4 M/atm. When the partial
pressure of helium above a sample of water is 0.400 atm, the concentration of helium in the water is
________ M.
A) 9.25 × 10-4
B) 1.08 × 103
C) 0.800
D) 1.48 × 10-4
E) 3.70 × 10-4
5) The solubility of oxygen gas in water at 25 °C and 1.0 atm pressure of oxygen is 0.041 g/L. The
solubility of oxygen in water at 4.0 atm and 25 °C is ________ g/L.
A) 0.041
B) 0.014
C) 0.31
D) 0.16
E) 4.0
6) The solubility of nitrogen gas in water at 25 °C and a nitrogen pressure of 1.0 atm is 6.9 × 10–4 M. The
solubility of nitrogen in water at a nitrogen pressure of 2.0 atm is ________ M.
A) 0.0014
B) 0.00086
C) 120
D) 0.0037
E) 2.0
7) On a clear day at sea level, with a temperature of 25 °C, the partial pressure of N2 in air is 0.78 atm and
the concentration of nitrogen in water is 5.3 × 10–4 M. When the partial pressure of N2 is ________ atm,
the concentration in water is 2.0 × 10-3 M.
A) 0.63
B) 0.68
C) 1.0
D) 3.0
E) 3.2
8) A solution is prepared by dissolving 27.7 g of CaCl2 in 375 g of water. The density of the resulting
solution is 1.05 g/mL. The concentration of CaCl2 is ________% by mass.
A) 6.88
B) 7.22
C) 0.0722
D) 0.0688
E) 6.24
9) The concentration of urea in a solution prepared by dissolving 16 g of urea in 25 g of H2O is ________%
by mass. The molar mass of urea is 60.0 g/mol.
A) 39
B) 64
C) 0.39
D) 0.64
E) 0.48
10) A solution contains 39% phosphoric acid by mass. This means that ________.
A) 100 g of this solution contains 39 g of phosphoric acid
B) 1 mL of this solution contains 39 g of phosphoric acid
C) 1 L of this solution has a mass of 39 g
D) 1 L of this solution contains 39 mL of phosphoric acid
E) the density of this solution is 3.9 g/mL
11) Calculate the molality of a 24.4% (by mass) aqueous solution of phosphoric acid (H3PO4).
A) 3.29 m
B) 323 m
C) 6.59 m
D) 1.65 m
E) The density of the solution is needed to solve the problem.
12) Calculate the molarity of phosphoric acid (H3PO4) in a 38.4% (by mass) aqueous solution.
A) 0.115 m
B) 0.206 m
C) 0.0514 m
D) 0.103 m
E) The density of the solution is needed to solve the problem.
13) Calculate the mole fraction of phosphoric acid (H3PO4) in a 38.5% (by mass) aqueous solution.
A) 0.103
B) 0.115
C) 0.206
D) 0.0516
E) The density of the solution is needed to solve the problem.
14) Calculate the molality of a 10.0% (by mass) aqueous solution of hydrochloric acid.
A) 3.32 m
B) 121 m
C) 1.10 m
D) 1.66 m
E) The density of the solution is needed to solve the problem.
15) Calculate the mole fraction of HCl in a 9.45% (by mass) aqueous solution.
A) 0.0491
B) 0.0516
C) 0.0981
D) 0.0245
E) The density of the solution is needed to solve the problem.
16) Calculate the molality of a 27.0% (by mass) aqueous solution of nitric acid.
A) 4.56
B) 370
C) 1.51
D) 2.28
E) The density of the solution is needed to solve the problem.
17) Calculate the mole fraction of nitric acid of an 8.37% (by mass) aqueous solution of nitric acid.
A) 0.0199
B) 0.0203
C) 0.0398
D) 0.00995
E) The density of the solution is needed to solve the problem.
18) A solution contains 30 ppm of benzene. The density of the solution is 1.00 g/mL. This means that
________.
A) there are 30 mg of benzene in 1.0 L of this solution
B) 100 g of the solution contains 30 g of benzene
C) 100 g of the solution contains 30 mg of benzene
D) the solution is 30% by mass of benzene
E) the molarity of the solution is 30 M
19) The concentration of nitrate ion in a solution that contains 0.800 M aluminum nitrate is _______ M.
A) 0.800
B) 0.400
C) 0.267
D) 2.40
E) 1.60
20) The concentration of KBr in a solution prepared by dissolving 2.10 g of KBr in 897 g of water is
________ molal.
A) 2.46
B) 0.0000207
C) 0.0197
D) 0.0167
E) 0.0186
21) The concentration of lead nitrate (Pb(NO3)2) in a 0.926 M solution is ________ molal. The density of
the solution is 1.202 g/mL.
A) 0.770
B) 2.13
C) 1.03
D) 0.819
E) 0.650
22) The concentration of a benzene solution prepared by mixing 15.0 g C6H6 with 38.0 g CCl4
is ________ molal.
A) 5.05
B) 2.40
C) 0.622
D) 0.395
E) 0.508
23) A solution is prepared by dissolving 11.0 g of NH3 in 250.0 g of water. The density of the resulting
solution is 0.974 g/mL. The mole fraction of NH3 in the solution is ________.
A) 0.0440
B) 0.0445
C) 0.940
D) 0.922
E) 16.8
24) A solution is prepared by adding 1.10 mol of KCl to 889 g of water. The concentration of KCl is
________ molal.
A) 1.24 × 10-3
B) 808
C) 0.808
D) 978
E) 1.24