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Problem 2
(a) Which kind of intermolecular attractive force is shown in each case here? (b) Predict which of the four interactions is the weakest. [Section 11.2]
Problem 4
If 42.0 kJ of heat is added to a 32.0-g sample of liquid meth-ane under 1 atm of pressure at a temperature of -170°C, what are the final state and temperature of the methane once the system equilibrates? Assume no heat is lost to the surroundings. The normal boiling point of methane is -161.5 °C. The specific heats of liquid and gaseous methane are 3.48 and 2.22 J/g-K, respectively. [Section 11.3]
Problem 5a
Using this graph of CS2 data, determine (a) the approximate vapor pressure of CS2 at 30°C,
Problem 6b
The molecules
have the same molecular formula (C3H8O) but different chemical structures. (b) Which molecule do you expect to have a larger dipole moment? [Sections 11.2 and 11.5]
Problem 7b
The phase diagram of a hypothetical substance is
(b) What is the physical state of the substance under the following conditions? (i) T = 150 K, P = 0.2 atm; (ii) T = 100 K, P = 0.8 atm; (iii) T = 300K, P = 1.0atm. [Section 11.6]
Problem 8a
At three different temperatures, T1, T2, and T3, the molecules in a liquid crystal align in these ways:
(a) At which temperature or temperatures is the substance in a liquid crystalline state? At those temperatures, which type of liquid crystalline phase is depicted?
Problem 8b
At three different temperatures, T1, T2, and T3, the molecules in a liquid crystal align in these ways:
(b) Which is the highest of these three temperatures? [Section 11.7]
Problem 9a
List the three states of matter in order of (a) increasing molecular disorder
Problem 9b
List the three states of matter in order of (b) increasing intermolecular attraction.
Problem 10a
(a) How does the average kinetic energy of molecules com- pare with the average energy of attraction between mole- cules in solids, liquids, and gases?
Problem 10c
(c) What happens to a gas if you put it under extremely high pressure?
Problem 12a
At room temperature, Si is a solid,CCl4 is a liquid, and Ar is a gas. List these substances in order of (a) increasing intermolecular energy of attraction and
Problem 13b
At standard temperature and pressure, the molar volumes of Cl2 and NH3 gases are 22.06 and 22.40 L, respectively. (b) On cooling to 160 K, both substances form crystalline solids. Do you expect the molar volumes to decrease or increase on cooling the gases to 160 K?
Problem 13c
At standard temperature and pressure, the molar volumes of Cl2 and NH3 gases are 22.06 and 22.40 L, respectively. (c) The densities of crystalline Cl2 and NH3 at 160 K are 2.02 and 0.84 g/cm3, respectively. Calculate their molar volumes.
Problem 13d
At standard temperature and pressure, the molar volumes of Cl2 and NH3 gases are 22.06 and 22.40 L, respectively. (d) Are the molar volumes in the solid state as similar as they are in the gaseous state? Explain.
Problem 14b
Benzoic acid, C6H5COOH, melts at 122 °C. The density in the liquid state at 130 °C is 1.08 g/cm3. The density of solid benzoic acid at 15 °C is 1.266 g/cm3. (b) If you converted a cubic centimeter of liquid benzoic acid into a solid, would the solid take up more, or less, volume than the original cubic centimeter of liquid?
Problem 15a
(a) Which type of intermolecular attractive force operates between all molecules?
Problem 15b
(b) Which type of intermolecular attractive force operates only between polar molecules?
Problem 15c
(c) Which type of intermolecular attractive force operates only between the hydrogen atom of a polar bond and a nearby small electronegative atom?
Problem 16b
(b) Which of these kinds of interactions are broken when a liquid is converted to a gas?
Problem 17b
Describe the intermolecular forces that must be overcome to convert these substances from a liquid to a gas: (b) CH3COOH,
Problem 18b
Which type of intermolecular force accounts for each of these differences? (b) Xe is a liquid at atmospheric pressure and 120 K, whereas Ar is a gas under the same conditions.
Problem 18d
Which type of intermolecular force accounts for each of these differences? (d) Acetone boils at 56 °C, whereas 2-methylpropane boils at -12 °C.
Problem 19
(a) List the following molecules in order of increasing polar- izability: GeCl4, CH4, SiCl4, SiH4, and GeBr4. (b) Predict the order of boiling points of the substances in part (a).
Problem 20b
True or false: (b) For the noble gases the dispersion forces decrease while the boiling points increase as you go down the column in the periodic table.
Problem 20e
True or false: (e) The larger the atom, the more polarizable it is.
Problem 21a
Which member in each pair has the greater dispersion forces? (a) H2O or H2S,
Problem 21c
Which member in each pair has the greater dispersion forces?(c) SiH4 or GeH4.
Problem 22c
Which member in each pair has the stronger intermolecular dispersion forces? (c) CH3CH2CH2Cl or (CH3)2CHCl
Problem 25b
(b) Which of the following molecules can form hydrogen bonds with other molecules of the same kind: CH3F, CH3NH2, CH3OH, CH3Br?
