5.
NAME: ______________________________________
AP CHEMISTRY
CHAPTER 8, #5
(Questions 1-3) Choose the letter that best answers the question or completes the statement.
_____ 1. Which of the following solutions has the HIGHEST boiling point?
A. 0.100 m
CaCl
2
B. 0.100 m
C
6
H
12
O
6
C. 0.100 m
KCl
D. 0.100 m
AgNO
3
E. 0.100 m
NaCl
_____ 2. MgF
2
is MOST soluble in which of the following liquids?
A. H
2
O
B. CCl
4
C. SiF
4
D. NO
2
E. PF
5
_____ 3. A solution is made by dissolving a nonvolatile solute in pure solvent.
Compared to the pure solvent, the solution
A. has a lower than normal boiling point
B.
C. has a higher vapor pressure has the same vapor pressure
D. has a lower than normal freezing point
E. is more nearly ideal
Answer the following to the best of your ability.
4. Vitamin K is involved in the blood clotting mechanism. When 0.500 grams is dissolved in 10.0 grams of camphor, the freezing point is lowered by 4.43
o
C. The molal freezing point depression constant for camphor is 40.0 o
C/ m
. Calculate the molar mass of Vitamin K.
A solution is 72% phosphoric acid by mass and has a density of 3.256 g/cm
Calculate the molarity of the solution.
3
.

6. Calculate the vapor pressure of a solution made by mixing 52.0 grams of sodium sulfate with 258 grams of water at 25°C. The vapor pressure of pure water at
25°C is 23.76 torr.
7. Seawater is 3.5% by mass sodium chloride. Calculate the normal boiling point of seawater. K b
for water is 0.52
o
C/ m
).
8. Which of the following should give a greater freezing point depression, a 1.50 m
C
12
H
22
O
11
solution, a 1.00 m
AlBr
3
a 0.25 m
NaCl solution? Explain your answer.
9.
(Questions 9-11) A solution is prepared by dissolving 2.53 grams of a substance (molar mass = 147.0 g/mol) in 25.86 grams of naphthalene (molar mass = 128.2 g/mol). The freezing point of pure naphthalene is 80.2°C. The solution prepared has a freezing point of 75.7°C.
Calculate the freezing-point depression constant of naphthalene.

10. Calculate the mole fraction of naphthalene when 2.53 grams of the substance dissolves in 25.86 grams of naphthalene.
11. Another trial is done in which a solution of 2.42 grams of a different undissociating unknown substance is dissolved in 26.7 grams of naphthalene. This solution is found to freeze at 76.2°C. Calculate the molar mass of the unknown substance.
12. Calculate the molarity of a 2.12 m
of sulfuric acid solution that has a density of
1.30 g/mL.
13. A phosphoric acid solution has a density of 1.562 g/cm
3
and is 85.0% solute.
Calculate the molarity, molality and mole fraction of phosphoric acid.
14. Calculate the osmotic pressure at 25°C of a 0.75 M solution of aluminum sulfate in water. Would you expect the measured osmotic pressure of 0.75 M aluminum sulfate to be higher or lower than the value you calculated? Explain