Question 1

Identify the solute with the highest van't Hoff factor.

Accepted Answer

A) nonelectrolyte 
B) NaCl 
C) MgSO4 
D) MgCl2 
E) FeCl3 
A) nonelectrolyte 
B) NaCl 
C) MgSO4 
D) MgCl2 
E) FeCl3

Question 2

Calculate the mass of lactose,C12H22O11,contained in 500.0 mL of solution if the measured vapour pressure of the solution is 121.2 mbar at 50 °C.The vapour pressure of pure water at 50 °C is 123.3 mbar; assume no change in volume occurs upon dissolution.

Accepted Answer

A) 118 g 
B) 165 g 
C) 239 g 
D) 94.6 g 
E) 280 g 
A) 118 g 
B) 165 g 
C) 239 g 
D) 94.6 g 
E) 280 g

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 
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

Determine the boiling point of a solution that contains 78.8 g of naphthalene (C10H8,molar mass = 128.16 g mol-1)dissolved in 722 mL of benzene (d = 0.877 g mL-1).Pure benzene has a boiling point of 80.1 °C and a boiling point elevation constant of 2.53 °C m-1.

Accepted Answer

A) 2.2 °C 
B) 2.5 °C 
C) 82.3 °C 
D) 80.4 °C 
E) 82.6 °C 
A) 2.2 °C 
B) 2.5 °C 
C) 82.3 °C 
D) 80.4 °C 
E) 82.6 °C

Question 5

Calculate the freezing point of a solution containing 5.0 grams of KCl and 550.0 grams of water.The molal freezing point depression constant ( $K_f$ )for water is $1.86 ^ { \circ } \mathrm { Cm } ^ { - 1 }$

Accepted Answer

A) -0.45 °C 
B) +0.45 °C 
C) -0.23 °C 
D) +0.23 °C 
E) 1.23 °C 
A) -0.45 °C 
B) +0.45 °C 
C) -0.23 °C 
D) +0.23 °C 
E) 1.23 °C

Question 6

How many moles of KF are contained in 347 g of water in a 0.175 mol kg-1 KF solution?

Accepted Answer

A) 1.65 × 10-2 mol KF 
B) 5.04 × 10-2 mol KF 
C) 6.07 × 10-2 mol KF 
D) 3.22 × 10-2 mol KF 
E) 1.98 × 10-2 mol KF 
A) 1.65 × 10-2 mol KF 
B) 5.04 × 10-2 mol KF 
C) 6.07 × 10-2 mol KF 
D) 3.22 × 10-2 mol KF 
E) 1.98 × 10-2 mol KF

Question 7

To make a 0.500 mol L-1 solution,one could take 0.500 moles of solute and add

Accepted Answer

A) 1.00 L of solvent. 
B) 1.00 kg of solvent. 
C) enough solvent to make 1.00 L of solution. 
D) enough solvent to make 1.00 kg of solution. 
A) 1.00 L of solvent. 
B) 1.00 kg of solvent. 
C) enough solvent to make 1.00 L of solution. 
D) enough solvent to make 1.00 kg of solution.

Question 8

Pentane (C5H12)is mixed with 75.8 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.The total solution mass is 206.6 g.Assume ideal behaviour.

Accepted Answer

A) 335 Torr 
B) 368 Torr 
C) 263 Torr 
D) 360 Torr 
E) 294 Torr 
A) 335 Torr 
B) 368 Torr 
C) 263 Torr 
D) 360 Torr 
E) 294 Torr

Question 9

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 10

A solid can be purified through which technique?

Accepted Answer

A) recrystallization 
B) dilution 
C) dissolution 
D) boiling 
E) melting 
A) recrystallization 
B) dilution 
C) dissolution 
D) boiling 
E) melting

Question 11

A solution is prepared by dissolving 76.3 g NaI in 545 g of water.Determine the mole fraction of NaI if the final volume of the solution is 576 mL.

Accepted Answer

A) 6.04 × 10-3 
B) 1.65 × 10-2 
C) 1.40 × 10-3 
D) 1.32 × 10-2 
E) 8.84 × 10-2 
A) 6.04 × 10-3 
B) 1.65 × 10-2 
C) 1.40 × 10-3 
D) 1.32 × 10-2 
E) 8.84 × 10-2

Question 12

Determine the vapour pressure of a solution at 25 °C that contains 76.6 g of glucose (C6H12O6)in 250.0 mL of water.The vapour pressure of pure water at 25 °C is 0.03173 bar.

Accepted Answer

A) 0.360 bar 
B) 0.318 bar 
C) 0.0308 bar 
D) 0.0387 bar 
E) 0.00567 bar 
A) 0.360 bar 
B) 0.318 bar 
C) 0.0308 bar 
D) 0.0387 bar 
E) 0.00567 bar

Question 13

An unknown nonelectrolyte and nonvolatile compound is dissolved in enough pure water to make 348 mL of solution.The vapour pressure above the solution drops from 198.7 mbar to 196.7 mbar when 100.0 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) 689 g mol-1 
B) 342 g mol-1 
C) 180 g mol-1 
D) 509 g mol-1 
E) 243 g mol-1 
A) 689 g mol-1 
B) 342 g mol-1 
C) 180 g mol-1 
D) 509 g mol-1 
E) 243 g mol-1

Question 14

Choose the statement below that is TRUE.

Accepted Answer

A) A solution will form between two substances if the solute-solvent interactions are of comparable strength to the solute-solute and solvent-solvent interactions. 
B) A solution will form between two substances if the solute-solvent interactions are small enough to be overcome by the solute-solute and solvent-solvent interactions. 
C) A solution will form between two substances if the solute-solute interactions are strong enough to overcome the solvent-solvent interactions. 
D) A solution will form between two substances only if the solvent-solvent interactions are weak enough to overcome the solute-solvent interactions. 
E) None of the above is true. 
A) A solution will form between two substances if the solute-solvent interactions are of comparable strength to the solute-solute and solvent-solvent interactions. 
B) A solution will form between two substances if the solute-solvent interactions are small enough to be overcome by the solute-solute and solvent-solvent interactions. 
C) A solution will form between two substances if the solute-solute interactions are strong enough to overcome the solvent-solvent interactions. 
D) A solution will form between two substances only if the solvent-solvent interactions are weak enough to overcome the solute-solvent interactions. 
E) None of the above is true.

Question 15

At 20 °C,a 0.389 mol L-1 aqueous solution of ammonium chloride has a density of 1.0064 $\mathrm { g } \mathrm { mL } ^ { - 1 }$ What is the mass % of ammonium chloride in the solution? The formula weight of $\mathrm { NH } _ { 4 }$ Cl is $53.50 \mathrm {~g} \mathrm {~mol} ^ { - 1 }$

Accepted Answer

A) 0.732% 
B) 2.59% 
C) 0.395% 
D) 0.387% 
E) 2.07% 
A) 0.732% 
B) 2.59% 
C) 0.395% 
D) 0.387% 
E) 2.07%

Question 16

An aqueous solution has a normal boiling point of 103.0 °C.What is the freezing point of this solution? For water $K \mathrm {~b} = 0.51 ^ { \circ } \mathrm { C } m ^ { - 1 }$ and $K \mathrm { f } = 1.86 ^ { \circ } \mathrm { C } m ^ { - 1 }$

Accepted Answer

A) -0.82 °C 
B) -3.0 °C 
C) -3.6 °C 
D) -11 °C 
A) -0.82 °C 
B) -3.0 °C 
C) -3.6 °C 
D) -11 °C

Question 17

Which cation in each set is expected to have the larger (more negative)hydration energy? 
I $\quad$Be2+ or Ca2+
II $\quad$Rb+ or Zn2+

Accepted Answer

A) Be2+ in set I and Rb+ in set II 
B) Be2+ in set I and Zn2+ in set II 
C) Ca2+ in set I and Rb+ in set II 
D) Ca2+ in set I and Zn2+ in set II 
A) Be2+ in set I and Rb+ in set II 
B) Be2+ in set I and Zn2+ in set II 
C) Ca2+ in set I and Rb+ in set II 
D) Ca2+ in set I and Zn2+ in set II

Question 18

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.

Question 19

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 
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 20

Determine the vapour pressure of a solution at 55 °C that contains 34.2 g NaCl in 375 mL of water.The vapour pressure of pure water at 55 °C is 0.1574 bar.

Accepted Answer

A) 0.153 bar 
B) 0.127 bar 
C) 0.0967 bar 
D) 0.108 bar 
E) 0.0907 bar 
A) 0.153 bar 
B) 0.127 bar 
C) 0.0967 bar 
D) 0.108 bar 
E) 0.0907 bar

Exam 12: Solutions

Identify the solute with the highest van't Hoff factor.

Calculate the mass of lactose,C12H22O11,contained in 500.0 mL of solution if the measured vapour pressure of the solution is 121.2 mbar at 50 °C.The vapour pressure of pure water at 50 °C is 123.3 mbar; assume no change in volume occurs upon dissolution.

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

Determine the boiling point of a solution that contains 78.8 g of naphthalene (C10H8,molar mass = 128.16 g mol-1)dissolved in 722 mL of benzene (d = 0.877 g mL-1).Pure benzene has a boiling point of 80.1 °C and a boiling point elevation constant of 2.53 °C m-1.

Calculate the freezing point of a solution containing 5.0 grams of KCl and 550.0 grams of water.The molal freezing point depression constant ( KfK_fKf​ )for water is 1.86∘Cm−11.86 ^ { \circ } \mathrm { Cm } ^ { - 1 }1.86∘Cm−1

How many moles of KF are contained in 347 g of water in a 0.175 mol kg-1 KF solution?

To make a 0.500 mol L-1 solution,one could take 0.500 moles of solute and add

Pentane (C5H12)is mixed with 75.8 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.The total solution mass is 206.6 g.Assume ideal behaviour.

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.

A solid can be purified through which technique?

A solution is prepared by dissolving 76.3 g NaI in 545 g of water.Determine the mole fraction of NaI if the final volume of the solution is 576 mL.

Determine the vapour pressure of a solution at 25 °C that contains 76.6 g of glucose (C6H12O6)in 250.0 mL of water.The vapour pressure of pure water at 25 °C is 0.03173 bar.

Choose the statement below that is TRUE.

Which cation in each set is expected to have the larger (more negative)hydration energy? I \quad Be2+ or Ca2+ II \quad Rb+ or Zn2+

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

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

Determine the vapour pressure of a solution at 55 °C that contains 34.2 g NaCl in 375 mL of water.The vapour pressure of pure water at 55 °C is 0.1574 bar.

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Filters

Calculate the mass of lactose,C₁₂H₂₂O₁₁,contained in 500.0 mL of solution if the measured vapour pressure of the solution is 121.2 mbar at 50 °C.The vapour pressure of pure water at 50 °C is 123.3 mbar; assume no change in volume occurs upon dissolution.

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

Determine the boiling point of a solution that contains 78.8 g of naphthalene (C₁₀H₈,molar mass = 128.16 g mol^-1)dissolved in 722 mL of benzene (d = 0.877 g mL^-1).Pure benzene has a boiling point of 80.1 °C and a boiling point elevation constant of 2.53 °C m^-1.

Calculate the freezing point of a solution containing 5.0 grams of KCl and 550.0 grams of water.The molal freezing point depression constant ( $K_f$ )for water is $1.86 ^ { \circ } \mathrm { Cm } ^ { - 1 }$

How many moles of KF are contained in 347 g of water in a 0.175 mol kg^-1 KF solution?

To make a 0.500 mol L^-1 solution,one could take 0.500 moles of solute and add

Pentane (C₅H₁₂)is mixed with 75.8 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.The total solution mass is 206.6 g.Assume ideal behaviour.

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.

Determine the vapour pressure of a solution at 25 °C that contains 76.6 g of glucose (C₆H₁₂O₆)in 250.0 mL of water.The vapour pressure of pure water at 25 °C is 0.03173 bar.

Which cation in each set is expected to have the larger (more negative)hydration energy? I $\quad$ Be²⁺ or Ca²⁺ II $\quad$ Rb⁺ or Zn²⁺