Question 1

Methane has a Henry's Law constant (k) of 9.88 × 10−2 mol/(L·atm) when dissolved in benzene at 25°C. How many grams of CH4 will dissolve in 3.00 L of benzene if the partial pressure of CH4 is 1.48 atm?

Accepted Answer

A)  0.0667 g
B)  0.146 g
C)  2.34 g
D)  4.83 g
E)  7.02 g E

Question 2

Saccharin, one of the first non-nutritive sweeteners used in soft-drinks, is 500 times sweeter than sugar in dilute aqueous solutions. The solubility of saccharin is 1.00 gram per 290 mL of solution. What is the molarity of a saturated saccharin solution? (ℳsaccharin = 183.2 g/mol)

Accepted Answer

A)  0.0188 M
B)  0.632 M
C)  1.58 M
D)  3.45 M
E)  None of these choices are correct. A

Question 3

Which of the following sets of conditions could exist when two liquids which are completely miscible in one another are mixed?

Accepted Answer

A)  Δ H soln > 0, entropy of system decreases
B)  Δ H soln ≈ 0, entropy of system decreases
C)  Δ H soln ≈ 0, entropy change of system ≈ 0
D)  Δ H soln ≈ 0, entropy of system increases
E)  None of these choices are correct. D

Question 4

An emulsion is a dispersion consisting of a

Accepted Answer

A)  solid in a liquid.
B)  liquid in a liquid.
C)  gas in a liquid.
D)  liquid in a solid.
E)  gas in a solid.

Question 5

The dimensions of typical colloidal particles are of the order of

Accepted Answer

A)  dm
B)  pm
C)  hm
D)  mm
E)  fm

Question 6

A 0.100 m K2SO4 solution has a freezing point of −0.43°C. What is the van't Hoff factor for this solution? Kf = 1.86°C/m

Accepted Answer

A)  0.77
B)  1.0
C)  2.3
D)  3.0
E)  >3.0

Question 7

Which of the following aqueous liquids will have the lowest freezing point?

Accepted Answer

A)  0.5 m C 12H 22O 11 (sucrose) 
B)  0.5 m Ca(NO 3) 2
C)  0.5 m NiSO 4
D)  0.5 m Li 3PO 4
E)  Pure water

Question 8

Carbon tetrachloride, once widely used in fire extinguishers and as a dry cleaning fluid, has been found to cause liver damage to those exposed to its vapors over long periods of time. What is the boiling point of a solution prepared by dissolving 375 g of sulfur (S8, ℳ= 256.5 g/mol) in 1250 g of CCl4? Kb = 5.05°C/m, boiling point of pure CCl4 = 76.7°C?

Accepted Answer

A)  70.8°C
B)  75.2°C
C)  78.2°C
D)  82.6°C
E)  >85°C

Question 9

Raoult's Law relates the vapor pressure of a solvent above a solution to the mole fraction of the solvent and the vapor pressure of the pure solvent.

Accepted Answer

A) True 
 B)False

Question 10

Diethyl ether has a vapor pressure of 400.0 torr at 18°C. When a sample of benzoic acid is dissolved in ether, the vapor pressure of the solution is 342 torr. What is the mole fraction of benzoic acid in the solution?

Accepted Answer

A)  0.0169
B)  0.0197
C)  0.145
D)  0.855
E)  None of these choices are correct.

Question 11

Helical segments of protein molecules arise through hydrogen bonding between C=O and N-H groups.

Accepted Answer

A) True 
 B)False

Question 12

Select the weakest electrolyte from the following set.

Accepted Answer

A)  Na 2 SO 4
B)  KCl
C)  CH 3 CH 2 COOH, propionic acid
D)  CaCl 2
E)  LiOH

Question 13

Human blood has a molar concentration of solutes of 0.30 M. What is the osmotic pressure of blood at 25°C?

Accepted Answer

A)  0.012 atm
B)  0.62 atm
C)  6.8 atm
D)  7.3 atm
E)  >10. atm

Question 14

A 0.89% (w/v) sodium chloride solution is referred to as physiological saline solution because it has the same concentration of salts as human blood. What is the molarity of a physiological saline solution?

Accepted Answer

A)  0.0028 M
B)  0.015 M
C)  0.15 M
D)  0.30 M
E)  0.35 M

Question 15

Select the strongest electrolyte from the following set.

Accepted Answer

A)  CH 3CH 2OH, ethanol
B)  LiNO 3
C)  C 6H 12O 6, glucose
D)  CCl 4
E)  HF

Question 16

Which of the following aqueous solutions should demonstrate the most non-ideal behavior?

Accepted Answer

A)  0.1 M NaI
B)  0.2 M CuSO 4
C)  0.5 M KBr
D)  2.0 M CuCl 2
E)  2.0 M CsCl

Question 17

Soda drinks bubble when the bottle is opened because

Accepted Answer

A)  the temperature of the soda increases.
B)  exposure to atmospheric pressure squeezes the carbon dioxide from solution.
C)  the partial pressure of carbon dioxide above the solution is reduced.
D)  atmospheric nitrogen molecules displace carbon dioxide molecules.
E)  the Henry's law constant changes due to the change in pressure.

Question 18

Children under the age of 6 with more than 0.10 ppm of lead in their blood can suffer a reduction in I.Q. or have behavior problems. What is the molality of a solution which contains 0.10 ppm of lead?

Accepted Answer

A)  4.8 × 10 −10 m
B)  4.8 × 10 −7 m
C)  4.8 × 10 −4 m
D)  4.8 × 10 −1 m
E)  None of these choices are correct.

Question 19

Consider the molecular substances I2, H2O, and C8H18. Which of them is/are soluble in CCl4?

Accepted Answer

A)  Only I 2
B)  Only H 2O
C)  Only C 8H 18
D)  I 2 and C 8H 18
E)  H 2O and C 8H 18

Question 20

A solution of ethanol (C2H6O) in water is sometimes used as a disinfectant. 1.00 L of this solution contains 553 g of ethanol and 335 g of water. What is the molality of the ethanol in this solution?

Accepted Answer

A)  0.392 m
B)  0.608 m
C)  13.5 m
D)  33.6 m
E)  35.8 m

Exam 13: The Properties of Mixtures: Solutions and Colloids

Methane has a Henry's Law constant (k) of 9.88 × 10⁻² mol/(L·atm) when dissolved in benzene at 25°C. How many grams of CH₄ will dissolve in 3.00 L of benzene if the partial pressure of CH₄ is 1.48 atm?

Saccharin, one of the first non-nutritive sweeteners used in soft-drinks, is 500 times sweeter than sugar in dilute aqueous solutions. The solubility of saccharin is 1.00 gram per 290 mL of solution. What is the molarity of a saturated saccharin solution? (ℳ_saccharin = 183.2 g/mol)