Question 1

At 20 °C, a 2.72 mol L-1 aqueous solution of ammonium chloride has a density of   What is the molality of ammonium chloride in the solution? The formula weight of   Cl is

Accepted Answer

A)  0.339 mol kg-1 
B)  2.72 mol kg-1 
C)  0.393 mol kg-1 
D)  13.6 mol kg-1 
E)  2.95 mol kg-1 
A)  0.339 mol kg-1 
B)  2.72 mol kg-1 
C)  0.393 mol kg-1 
D)  13.6 mol kg-1 
E)  2.95 mol kg-1

Question 2

A solution of methanol and water has a vapour pressure of 248 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)    = 0.990,   = 0.010 
B)    = 0.940,   = 0.060 
C)    = 0.960,   = 0.040 
D)    = 0.910,   = 0.090 
E)    = 0.900,   = 0.100 
A)    = 0.990,   = 0.010 
B)    = 0.940,   = 0.060 
C)    = 0.960,   = 0.040 
D)    = 0.910,   = 0.090 
E)    = 0.900,   = 0.100

Question 3

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. 
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 4

Determine the molality of an aqueous solution prepared by dissolving 0.112 moles of LiCl in 13.7 moles of H2O.

Accepted Answer

A)  0.454 mol kg-1 
B)  0.220 mol kg-1 
C)  0.818 mol kg-1 
D)  0.122 mol kg-1 
E)  0.153 mol kg-1 
A)  0.454 mol kg-1 
B)  0.220 mol kg-1 
C)  0.818 mol kg-1 
D)  0.122 mol kg-1 
E)  0.153 mol kg-1

Question 5

Choose the situation below that would result in an endothermic ΔsolutionH.

Accepted Answer

A)  when   >   
B)  when      
E)  There isn't enough information to determine the answer. 
A)  when   >   
B)  when      
E)  There isn't enough information to determine the answer.

Question 6

Calculate the mole fraction of total ions in an aqueous solution prepared by dissolving 0.400 moles of MgCl2 in 850.0 g of water.

Accepted Answer

A)  0.00841 
B)  0.0270 
C)  0.00900 
D)  0.0248 
E)  0.0167 
A)  0.00841 
B)  0.0270 
C)  0.00900 
D)  0.0248 
E)  0.0167

Question 7

Identify the major force between acetone and chloroform.

Accepted Answer

A)  dipole-dipole 
B)  dispersion 
C)  hydrogen bonding 
D)  ion-ion 
E)  ion-dipole 
A)  dipole-dipole 
B)  dispersion 
C)  hydrogen bonding 
D)  ion-ion 
E)  ion-dipole

Question 8

Calculate the volume of solution that has a vapour pressure of 25.8 mbar and contains 200.3 g of galactose, C6H12O6, at a temperature of 22.0 °C. The vapour pressure of pure water at 22 °C is 26.40 mbar, the density of water is 1.00 g mL-1, and assume no change in volume occurs upon dissolution.

Accepted Answer

A)  200 mL 
B)  91.3 mL 
C)  769 mL 
D)  862 mL 
E)  981 mL 
A)  200 mL 
B)  91.3 mL 
C)  769 mL 
D)  862 mL 
E)  981 mL

Question 9

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

Accepted Answer

A)  0.50 mol kg-1 C3H8O3 
B)  0.50 mol kg-1 C2H6O2 
C)  0.50 mol kg-1 C6H12O6 
D)  0.50 mol kg-1 C12H22O11 
E)  They all have about the same vapour pressure. 
A)  0.50 mol kg-1 C3H8O3 
B)  0.50 mol kg-1 C2H6O2 
C)  0.50 mol kg-1 C6H12O6 
D)  0.50 mol kg-1 C12H22O11 
E)  They all have about the same vapour pressure.

Question 10

Which of the following compounds will be most soluble in pentane (C5H12)?

Accepted Answer

A)  pentanol (CH3CH2CH2CH2CH2OH) 
B)  benzene (C6H6) 
C)  acetic acid (CH3CO2H) 
D)  ethyl methyl ketone (CH3CH2COCH3) 
E)  None of these compounds should be soluble in pentane. 
A)  pentanol (CH3CH2CH2CH2CH2OH) 
B)  benzene (C6H6) 
C)  acetic acid (CH3CO2H) 
D)  ethyl methyl ketone (CH3CH2COCH3) 
E)  None of these compounds should be soluble in pentane.

Question 11

Explain why water does not dissolve in gasoline.

Accepted Answer

Water is p

Question 12

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

Question 13

An unknown nonelectrolyte and nonvolatile compound is dissolved in enough pure water to make 229 mL of solution. The vapour pressure above the solution drops from 233.7 Torr to 229.1 Torr when 82.3 g of the compound is dissolved at constant temperature. Determine the molar mass of the unknown compound. Assume no change in volume occurs upon dissolution.

Accepted Answer

A)  323 g mol-1 
B)  480 g mol-1 
C)  414 g mol-1 
D)  459 g mol-1 
E)  508 g mol-1 
A)  323 g mol-1 
B)  480 g mol-1 
C)  414 g mol-1 
D)  459 g mol-1 
E)  508 g mol-1

Question 14

What is the molality of a glucose solution prepared by dissolving 18.0 g of glucose, C6H12O6, in 125.9 g of water?

Accepted Answer

A)  7.94 × 10-4 mol kg-1 
B)  0. 143 mol kg-1 
C)  0.695 mol kg-1 
D)  0.794 mol kg-1 
A)  7.94 × 10-4 mol kg-1 
B)  0. 143 mol kg-1 
C)  0.695 mol kg-1 
D)  0.794 mol kg-1

Question 15

A 125.0 mL sample of an aqueous solution at 25 °C contains 29.4 mg of an unknown nonelectrolyte compound. If the solution has an osmotic pressure of 24.4 mbar, what is the molar mass of the unknown compound?

Accepted Answer

A)  116 g mol-1 
B)  281 g mol-1 
C)  239 g mol-1 
D)  98.6 g mol-1 
E)  311 g mol-1 
A)  116 g mol-1 
B)  281 g mol-1 
C)  239 g mol-1 
D)  98.6 g mol-1 
E)  311 g mol-1

Question 16

A mixture of chloroform and acetone has a vapour pressure of 311 Torr. Calculate the mole fraction of acetone in the mixture. The vapour pressures of chloroform and acetone are 295 Torr and 332 Torr, respectively. Assume ideal behaviour.

Accepted Answer

A)  0.432 
B)  0.730 
C)  0.270 
D)  0.619 
E)  0.568 
A)  0.432 
B)  0.730 
C)  0.270 
D)  0.619 
E)  0.568

Question 17

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

Question 18

At 20 °C, an aqueous solution that is 24.0% by mass in ammonium chloride has a density of 1.0674   What is the molarity of ammonium chloride in the solution? The formula weight of   Cl is

Accepted Answer

A)  0.209 mol L-1 
B)  0.0445 mol L-1 
C)  22.5 mol L-1 
D)  0.479 mol L-1 
E)  4.79 mol L-1 
A)  0.209 mol L-1 
B)  0.0445 mol L-1 
C)  22.5 mol L-1 
D)  0.479 mol L-1 
E)  4.79 mol L-1

Question 19

A small amount, 6.78 g, of pentane (C5H12) is mixed with 100.00 g hexane (C6H14). Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.

Accepted Answer

A)  201 Torr 
B)  158 Torr 
C)  183 Torr 
D)  164 Torr 
E)  172 Torr 
A)  201 Torr 
B)  158 Torr 
C)  183 Torr 
D)  164 Torr 
E)  172 Torr

Question 20

Give the reason that antifreeze is added to a car radiator.

Accepted Answer

A)  The freezing point is lowered and the boiling point is elevated. 
B)  The freezing point is elevated and the boiling point is lowered. 
C)  The freezing point and the boiling point are elevated. 
D)  The freezing point and the boiling point are lowered. 
E)  None of the above. 
A)  The freezing point is lowered and the boiling point is elevated. 
B)  The freezing point is elevated and the boiling point is lowered. 
C)  The freezing point and the boiling point are elevated. 
D)  The freezing point and the boiling point are lowered. 
E)  None of the above.

Exam 12: Solutions

At 20 °C, a 2.72 mol L-1 aqueous solution of ammonium chloride has a density of What is the molality of ammonium chloride in the solution? The formula weight of Cl is

A solution of methanol and water has a vapour pressure of 248 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.

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.

Determine the molality of an aqueous solution prepared by dissolving 0.112 moles of LiCl in 13.7 moles of H2O.

Choose the situation below that would result in an endothermic ΔsolutionH.

Calculate the mole fraction of total ions in an aqueous solution prepared by dissolving 0.400 moles of MgCl2 in 850.0 g of water.

Identify the major force between acetone and chloroform.

Calculate the volume of solution that has a vapour pressure of 25.8 mbar and contains 200.3 g of galactose, C6H12O6, at a temperature of 22.0 °C. The vapour pressure of pure water at 22 °C is 26.40 mbar, the density of water is 1.00 g mL-1, and assume no change in volume occurs upon dissolution.

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

Which of the following compounds will be most soluble in pentane (C5H12)?

Explain why water does not dissolve in gasoline.

What volume of 3.00 mol L-1 CH3OH solution is needed to provide 0. 220 mol of CH3OH?

What is the molality of a glucose solution prepared by dissolving 18.0 g of glucose, C6H12O6, in 125.9 g of water?

A 125.0 mL sample of an aqueous solution at 25 °C contains 29.4 mg of an unknown nonelectrolyte compound. If the solution has an osmotic pressure of 24.4 mbar, what is the molar mass of the unknown compound?

A mixture of chloroform and acetone has a vapour pressure of 311 Torr. Calculate the mole fraction of acetone in the mixture. The vapour pressures of chloroform and acetone are 295 Torr and 332 Torr, respectively. Assume ideal behaviour.

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.

At 20 °C, an aqueous solution that is 24.0% by mass in ammonium chloride has a density of 1.0674 What is the molarity of ammonium chloride in the solution? The formula weight of Cl is

A small amount, 6.78 g, of pentane (C5H12) is mixed with 100.00 g hexane (C6H14). Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.

Give the reason that antifreeze is added to a car radiator.

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At 20 °C, a 2.72 mol L^-1 aqueous solution of ammonium chloride has a density of What is the molality of ammonium chloride in the solution? The formula weight of Cl is

Determine the molality of an aqueous solution prepared by dissolving 0.112 moles of LiCl in 13.7 moles of H₂O.

Choose the situation below that would result in an endothermic Δ_solutionH.

Calculate the mole fraction of total ions in an aqueous solution prepared by dissolving 0.400 moles of MgCl₂ in 850.0 g of water.

Which of the following compounds will be most soluble in pentane (C₅H₁₂)?

What volume of 3.00 mol L^-1 CH₃OH solution is needed to provide 0. 220 mol of CH₃OH?

What is the molality of a glucose solution prepared by dissolving 18.0 g of glucose, C₆H₁₂O₆, in 125.9 g of water?

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.

A small amount, 6.78 g, of pentane (C₅H₁₂) is mixed with 100.00 g hexane (C₆H₁₄). Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.