Name: __________________________
Date: ____________ Period: ________
AP Chemistry – OHS – Chapter 11 Practice Work
Mr. Daniel
1. What type of intermolecular forces must be overcome in converting each of the
following from a liquid to a gas?
(a) CO2
(b) NH3
(c) CHCl3
(d) CCl4
2. Rank the following in order of increasing strength of intermolecular forces in the pure
substances.
(a) CH3CH2CH2CH3 (butane)
(b) CH3OH (methanol)
(c) He
3. Which of the following compounds would be expected to form intermolecular
hydrogen bonds in the liquid state?
(a) H2Se
(b) HCO2H (formic acid)
(c) HI
(d) Acetone
Liquids
4. The enthalpy of vaporization of liquid mercury is 59.11 kJ/mol. What quantity of heat
is required to vaporize 0.500 mL if mercury at 357°C, its normal boiling point? The
density of mercury is 13.53 g/mL.
5. Answer the following questions using Figure 11.12 (pg. 426 in book):
(a) What is the equilibrium vapor pressure of diethyl ether at room temperature
(approximately 20°C)?
(b) Place the three compounds in Figure 11.12 in order of increasing
intermolecular forces.
(c) If the pressure in a flask is 400 mm Hg and if the temperature is 40°C, which
of the three compounds (diethyl ether, ethanol, and water) are predominately
liquids and which are gases?
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Name: __________________________
Date: ____________ Period: ________
6. Refer to figure 11.12 (pg. 426 in book) as an aid in answering these questions:
(a) You put some water at 60°C in plastic milk carton and seal the top very tightly
so gas cannot enter or leave the carton. What happens when the water cools?
(b) If you put a few drops of liquid diethyl ether on your hand, does it evaporate
completely or remain a liquid?
7. Place the following four compounds in order of increasing boiling points:
(a) C5H12 (b) CCl4 (c) C2H6 (d) Ne. (hint: draw the Lewis structures first)
8. Answer each of the following questions with increase, decrease, or does not change.
(a) If the intermolecular forces in a liquid increase, the normal boiling point of the
liquid _________________.
(b) If the intermolecular forces in a liquid decrease, the vapor pressure of the
liquid _________________.
(c) If the surface area of a liquid decreases, the vapor pressure _______________.
(d) If the temperature of a liquid increases, the equilibrium vapor pressure
_________________.
9. What types of intermolecular forces are important in the liquid phase of:
(a) C2H6
(b) (CH3)2CHOH
10. Cooking oil floats on top of water. From this observation, what conclusions can you
draw regarding the polarity or hydrogen-bonding ability of molecules found in cooking
oil?
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Name: __________________________
Date: ____________ Period: ________
15) Vapor pressure data is given here for octane, C8H18.
a) With your calculator graph the data and then,
using the Clausius–Clapeyron Equation, (below)
calculate the molar enthalpy of vaporization
of octane. (hint: remember the slope)
Ln P = -ΔHvap x 1
R
T
+C
b) Using the first two sets of data points from the graph above, use the alternative,
2-point method to calculate the ΔHvap for octane. Compare the two results.
c) Using the results from section one and what you know about boiling point, vapor
pressure and temperature relationships, use the Clausius–Clapeyron Equation to
calculate the boiling point of octane.
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Name: __________________________
Date: ____________ Period: ________
11. Select the substance in each of the following pairs that should have the higher boiling
point. Explain the logic behind each answer:
(a) Br2 or ICl:
(b) neon or krypton:
(c) CH3CH2OH (ethanol) or C2H4O (ethylene oxide, structure shown here)
12) Rank the following molecules in order of increasing intermolecular forces: CH3Cl,
HCO2H (formic acid –see structure on question 3), and CO2. Explain your reasoning.
13) Rationalize the observation that CH3CH2CH2OH, 1-propanol, has a boiling point of
97.2°C, whereas a compound with the same empirical formula and molar mass,
methyl ethyl ether (CH3 CH2OCH3) boils at 7.4°C.
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Name: __________________________
Date: ____________ Period: ________
14) Use the vapor pressure curves illustrated here to answer the questions that follow:
(a) What is the vapor pressure of ethanol, C2H5OH, at 60°
(b) Considering only carbon disulfide (CS2) and ethanol, which has the
stronger intermolecular forces in the liquid state? How do you know?
(c) At what temperature does heptane (C7H16) have a vapor pressure of 500
mm Hg?
(d) What are the approximate normal boiling points of each of the three
substances?
(e) At a pressure of 300 mm Hg and a temperature of 70°C, is each
substance a liquid, a gas, or a mixture of liquid and gas?
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