Question 1

A solution of methanol and water has a vapour pressure of 213 Torr. What would you predict as the mole fractions of each component, assuming ideal behaviour? The vapour pressures of methanol and water are 256 Torr and 55.3 Torr, respectively.

Accepted Answer

A)    = 0.214,  = 0.786 
B)    = 0.786,  = 0.214
C)    = 0.885,  = 0.115
D)    = 0.900,  = 0.100
E)    = 0.115,  = 0.885

Question 2

A solution is prepared by dissolving 49.3 g of KBr in enough water to form 473 mL of solution. Calculate the mass % of KBr in the solution if the density is 1.12 g mL-1.

Accepted Answer

A)  10.4%
B)  8.57%
C)  10.1%
D)  11.7%
E)  9.31%

Question 3

Choose the solvent below that would show the greatest boiling point elevation when used to make a 0.10 mol kg-1 nonelectrolyte solution.

Accepted Answer

A)  CCl4, Kb = 29.9 °C m-1
B)  C6H6, Kb = 5.12 °C m-1
C)  CH3CH2OCH2CH3, Kb = 1.79 °C m-1
D)  CH3CH2OH, Kb = 1.99 °C m-1
E)  CHCl3, Kb = 4.70 °C m-1

Question 4

What is the weight percent of a caffeine solution made by dissolving 8.35 g of caffeine, C8H10N4O2, in 75 g of benzene, C6H6?

Accepted Answer

A)  0.010%
B)  0.011%
C)  10%
D)  11%

Question 5

Choose the aqueous solution with the lowest vapour pressure. These are all solutions of nonvolatile solutes and you should assume ideal van't Hoff factors where applicable.

Accepted Answer

A)  0.120 mol kg-1 C2H6O2
B)  0.040 mol kg-1 (NH4) 2SO4
C)  0.060 mol kg-1 K2CO3
D)  0.030 mol kg-1 LiC2H3O2
E)  They all have the same vapour pressure.

Question 6

Which of the following defines dynamic equilibrium of a solution?

Accepted Answer

A)  rate of dissolution = rate of deposition
B)  rate of dissolution 
C)  rate of dissolution > rate of deposition
D)  rate of bubbling > rate of dissolving
E)  rate of evaporating > rate of condensing

Question 7

Calculate the molality of a solution that is prepared by mixing 25.5 mL of CH3OH (d = 0.792 g mL-1) and 387 mL of CH3CH2CH2OH (d = 0.811 g mL-1) .

Accepted Answer

A)  0.630 mol kg-1
B)  0.812 mol kg-1
C)  1.57 mol kg-1
D)  2.01 mol kg-1
E)  4.98 mol kg-1

Question 8

The boiling point elevation of an aqueous sucrose solution is found to be 0.39 °C. What mass of sucrose (molar mass = 342.30 g mol-1) would be needed to dissolve in 500.0 g of water? Kb (water) = 0.512 °C m-1.

Accepted Answer

A)  261 g sucrose
B)  528 g sucrose
C)  762 g sucrose
D)  223 g sucrose
E)  130. g sucrose

Question 9

A nonelectrolyte compound with a molar mass of 648 g mol-1 was dissolved in enough water to make 250 mL of solution at 25 °C and produced an osmotic pressure of 27.4 mbar. Calculate the mass of the compound, in g, used to make this solution.

Accepted Answer

A)  0.267 g
B)  0.179 g
C)  0.106 g
D)  0.0873 g
E)  0.236 g

Question 10

Place the following aqueous solutions of nonvolatile, nonionic compounds in order of decreasing osmotic pressure. I. 0.011 mol L-1 sucrose II. 0.00095 mol L-1 glucose III. 0.0060 mol L-1 glycerin

Accepted Answer

A)  I > III > II
B)  I > II > III
C)  II > III > I
D)  III > I > II
E)  II > I > III

Question 11

How many moles of KF are contained in 244 mL of 0.135 mol kg-1 KF solution? The density of the solution is 1.22 g mL-1.

Accepted Answer

A)  4.31 × 10-2 mol KF
B)  4.02 × 10-2 mol KF
C)  3.29 × 10-2 mol KF
D)  2.32 × 10-2 mol KF
E)  1.67 × 10-2 mol KF

Question 12

A solution of LiCl in water is 20.0 wt% LiCl. What is the mole fraction of LiCl? Assume the density of the solution is 1.00 g mL-1.

Accepted Answer

A)  0.0960
B)  0.106
C)  0.472
D)  4.44

Question 13

Choose the aqueous solution below with the lowest freezing point. These are all solutions of nonvolatile solutes and you should assume ideal van't Hoff factors where applicable.

Accepted Answer

A)  0.075 mol kg-1 NaI
B)  0.075 mol kg-1 (NH4) 3PO4
C)  0.075 mol kg-1 NaBrO4
D)  0.075 mol kg-1 LiCN
E)  0.075 mol kg-1 KNO2

Question 14

Determine the Henry's law constant for ammonia in water at 25 °C if an ammonia pressure of 0.022 bar produces a solution with a concentration of 1.3 mol L-1.

Accepted Answer

A)  59 mol L-1 bar-1
B)  0.017 mol L-1 bar-1
C)  0.029 mol L-1 bar-1
D)  35 mol L-1 bar-1
E)  0.038 mol L-1 bar-1

Question 15

What mass of NaCl is contained in 24.88 g of a 15.00% by mass solution of NaCl in water?

Accepted Answer

A)  20.00 g
B)  21.15 g
C)  3.73 g
D)  1.50 g
E)  12.44 g

Question 16

Determine ΔsoluteH for KBr if the ΔsolutionH for KBr is +19.9 kJ mol-1 and the ΔhydrationH for KBr is -670. kJ mol-1.

Accepted Answer

A)  +650 kJ mol-1
B)  -650 kJ mol-1
C)  +690 kJ mol-1
D)  -710 kJ mol-1
E)  -690 kJ mol-1

Question 17

Which of the following solutions will have the lowest freezing point?

Accepted Answer

A)  0.010 mol kg-1 K Br
B)  0.010 mol kg-1 Na2CO3
C)  0.035 mol kg-1 CH3CH2OH 
D)  0.015 mol kg-1 BaCl2

Question 18

What volume of 3.00 mol L-1 CH3OH solution is needed to provide 0.220 mol of CH3OH?

Accepted Answer

A)  1.52 mL
B)  13.6 mL
C)  73.3 mL
D)  660 mL

Question 19

Identify the compound whose solubility is least affected by temperature.

Accepted Answer

A)  Na2SO4
B)  K2Cr2O7
C)  KNO3
D)  KClO3
E)  NaCl

Question 20

A solution is prepared by dissolving 98.6 g of NaCl in enough water to form 875 mL of solution. Calculate the mass % of the solution if the density of the solution is 1.06 g mL-1.

Accepted Answer

A)  11.3%
B)  12.7%
C)  9.4%
D)  10.6%
E)  11.9%

Exam 12: Solutions

Determine the Henry's law constant for ammonia in water at 25 °C if an ammonia pressure of 0.022 bar produces a solution with a concentration of 1.3 mol L-1.

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Which of the following defines dynamic equilibrium of a solution?

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What mass of NaCl is contained in 24.88 g of a 15.00% by mass solution of NaCl in water?

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Place the following aqueous solutions of nonvolatile, nonionic compounds in order of decreasing osmotic pressure. I. 0.011 mol L-1 sucrose II. 0.00095 mol L-1 glucose III. 0.0060 mol L-1 glycerin

Correct AnswerverifiedShow Answer

A solution of methanol and water has a vapour pressure of 213 Torr. What would you predict as the mole fractions of each component, assuming ideal behaviour? The vapour pressures of methanol and water are 256 Torr and 55.3 Torr, respectively.

Correct AnswerverifiedShow Answer

A solution of LiCl in water is 20.0 wt% LiCl. What is the mole fraction of LiCl? Assume the density of the solution is 1.00 g mL-1.

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What volume of 3.00 mol L-1 CH3OH solution is needed to provide 0.220 mol of CH3OH?

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Which of the following solutions will have the lowest freezing point?

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A solution is prepared by dissolving 49.3 g of KBr in enough water to form 473 mL of solution. Calculate the mass % of KBr in the solution if the density is 1.12 g mL-1.

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What is the weight percent of a caffeine solution made by dissolving 8.35 g of caffeine, C8H10N4O2, in 75 g of benzene, C6H6?

Correct AnswerverifiedShow Answer

Choose the solvent below that would show the greatest boiling point elevation when used to make a 0.10 mol kg-1 nonelectrolyte solution.

Correct AnswerverifiedShow Answer

Calculate the molality of a solution that is prepared by mixing 25.5 mL of CH3OH (d = 0.792 g mL-1) and 387 mL of CH3CH2CH2OH (d = 0.811 g mL-1) .

Correct AnswerverifiedShow Answer

Identify the compound whose solubility is least affected by temperature.

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Choose the aqueous solution below with the lowest freezing point. These are all solutions of nonvolatile solutes and you should assume ideal van't Hoff factors where applicable.

Correct AnswerverifiedShow Answer

A solution is prepared by dissolving 98.6 g of NaCl in enough water to form 875 mL of solution. Calculate the mass % of the solution if the density of the solution is 1.06 g mL-1.

Correct AnswerverifiedShow Answer

The boiling point elevation of an aqueous sucrose solution is found to be 0.39 °C. What mass of sucrose (molar mass = 342.30 g mol-1) would be needed to dissolve in 500.0 g of water? Kb (water) = 0.512 °C m-1.

Correct AnswerverifiedShow Answer

Choose the aqueous solution with the lowest vapour pressure. These are all solutions of nonvolatile solutes and you should assume ideal van't Hoff factors where applicable.

Correct AnswerverifiedShow Answer

How many moles of KF are contained in 244 mL of 0.135 mol kg-1 KF solution? The density of the solution is 1.22 g mL-1.

Correct AnswerverifiedShow Answer

Determine ΔsoluteH for KBr if the ΔsolutionH for KBr is +19.9 kJ mol-1 and the ΔhydrationH for KBr is -670. kJ mol-1.

Correct AnswerverifiedShow Answer

A nonelectrolyte compound with a molar mass of 648 g mol-1 was dissolved in enough water to make 250 mL of solution at 25 °C and produced an osmotic pressure of 27.4 mbar. Calculate the mass of the compound, in g, used to make this solution.

Correct AnswerverifiedShow Answer

Determine the Henry's law constant for ammonia in water at 25 °C if an ammonia pressure of 0.022 bar produces a solution with a concentration of 1.3 mol L^-1.

Correct Answer
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Correct Answer
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Correct Answer
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Place the following aqueous solutions of nonvolatile, nonionic compounds in order of decreasing osmotic pressure. I. 0.011 mol L^-1 sucrose II. 0.00095 mol L^-1 glucose III. 0.0060 mol L^-1 glycerin

Correct Answer
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Correct Answer
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A solution of LiCl in water is 20.0 wt% LiCl. What is the mole fraction of LiCl? Assume the density of the solution is 1.00 g mL^-1.

Correct Answer
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What volume of 3.00 mol L^-1 CH₃OH solution is needed to provide 0.220 mol of CH₃OH?

Correct Answer
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Correct Answer
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A solution is prepared by dissolving 49.3 g of KBr in enough water to form 473 mL of solution. Calculate the mass % of KBr in the solution if the density is 1.12 g mL^-1.

Correct Answer
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What is the weight percent of a caffeine solution made by dissolving 8.35 g of caffeine, C₈H₁₀N₄O₂, in 75 g of benzene, C₆H₆?

Correct Answer
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Choose the solvent below that would show the greatest boiling point elevation when used to make a 0.10 mol kg^-1 nonelectrolyte solution.

Correct Answer
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Calculate the molality of a solution that is prepared by mixing 25.5 mL of CH₃OH (d = 0.792 g mL^-1) and 387 mL of CH₃CH₂CH₂OH (d = 0.811 g mL^-1) .

Correct Answer
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Correct Answer
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Correct Answer
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A solution is prepared by dissolving 98.6 g of NaCl in enough water to form 875 mL of solution. Calculate the mass % of the solution if the density of the solution is 1.06 g mL^-1.

Correct Answer
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The boiling point elevation of an aqueous sucrose solution is found to be 0.39 °C. What mass of sucrose (molar mass = 342.30 g mol^-1) would be needed to dissolve in 500.0 g of water? K_b (water) = 0.512 °C m^-1.

Correct Answer
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Correct Answer
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How many moles of KF are contained in 244 mL of 0.135 mol kg^-1 KF solution? The density of the solution is 1.22 g mL^-1.

Correct Answer
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Determine Δ_soluteH for KBr if the Δ_solutionHfor KBr is +19.9 kJ mol^-1 and the Δ_hydrationH for KBr is -670. kJ mol^-1.

Correct Answer
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A nonelectrolyte compound with a molar mass of 648 g mol^-1 was dissolved in enough water to make 250 mL of solution at 25 °C and produced an osmotic pressure of 27.4 mbar. Calculate the mass of the compound, in g, used to make this solution.

Correct Answer
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