AP Chem Review Sheet Ch. 10-11
Solids, Liquids, & Gases
1. Consider methyl alcohol, an organic compound of molecular formula CH3OH.
a. What kind of intermolecular forces would you expect to find in methyl alcohol?
b. How would you expect the normal boiling point of CH3OH to compare to that of O2? To
C2H5OH? To NaCl? To SiO2?
c. Would you expect CH3OH to conduct electricity? How would its water solubility
compare to that of O2? To SiO2?
d. Give the symbol of a solid nonmetal that is a better conductor than CH3OH. Give the
formula of a solid compound that, unlike CH3OH, has a network structure.
e. The normal boiling point of CH3OH is 65°C, the normal freezing point is -98°C, and the
critical temperature is 239°C. Draw a rough sketch of the phase diagram of methyl
alcohol, assuming the solid is more dense than the liquid.
f. If you wanted to purify methyl alcohol by sublimation, at what temperature would you
operate?
g. A sample of methyl alcohol vapor at 250°C and 1 atm is cooled at constant pressure. At
what temperature does liquid first appear?
h. Taking the normal boiling point of CH3OH to be 65°C and its heat of vaporization to be
38.0 kJ/mol, estimate its normal vapor pressure at 25°C. Estimate the temperature at
which its vapor pressure is 0.500 atom.
i. A sample of 1.00 mL of CH3OH (d = 0.792 g/mL) is placed in a one-liter flask at 35°C,
where its vapor pressure is 203 mmHg Show by calculation whether there is any liquid
left in the flask when equilibrium is established.
2. Consider camphor, C10H16O (MM = 152 g/mol), a substance obtained from the Formosa
camphor tree. It has considerable use in the polymer and drug industries.
A solution of camphor is prepared by mixing 30.0 g of camphor with 1.25 L of ethanol,
C2H5OH (d = 0.789 g/mL). Assume no change in volume when the solution is prepared.
a.
b.
c.
d.
e.
What is the mass percent of camphor in the solution?
What is the concentration of camphor is parts per million?
What is the molarity of the solution?
What is the molality of the solution?
The vapor pressure of pure ethanol at 25°C is 59.0 mmHg. What is the vapor pressure of
ethanol in the solution at this temperature?
f. What is the osmotic pressure of the solution at 25°C?
g. What is the boiling point of the solution? The normal boiling point of ethanol is 78.26°C
(kb = 1.22°C/m).
h. Camphor can also be used as a solvent. It is used in the Rast method for determining
molar mass. The molar mass of cortisone acetate is determined by dissolving 2.50 g in
50.0 g camphor (kf = 40.0°C/m). The freezing point of the mixture is determined to be
173.44°C; that of pure camphor is 178.40°C. What is the molar mass of cortisone acetate?
ANSWERS:
1. a. Dispersion, H bonds
b. Higher than O2 (dispersion only), lower than the others (C2H5OH - more dispersion; NaCl ionic; SiO2 - network)
c. no; higher than O2 (dispersion only) or SiO2 (network)
d. C(graphite) or Si; SiO2, NaCl, and so on
e. (Be sure fusion line has a positive slope)
f. below about -98°C
g. 65°C
h. 123 mmHg, 49°C
i. yes
2. a. 2.95%
b. 2.95 x 104 ppm
c. 0.158 M
d. 0.200 m
e. 58.5 mmHg
f. 3.87 atm
g. 78.50°C
h. 403 g/mol