Solids, Liquids, and Intermolecular Forces: Review Questions for AP Chemistry

Review the following concepts if necessary:

• Structures and Intermolecular Forces for AP Chemistry
• The Liquid State for AP Chemistry
• The Solid State for AP Chemistry
• Phase Diagrams and Phase Changes for AP Chemistry

Problems

Answer the following questions. You have 20 minutes, and you may not use a calculator. You may use the periodic table at the back of this book.

Choose from the following descriptions of solids for questions 1–4.

1. composed of macromolecules held together by strong bonds
2. composed of atoms held together by delocalized electrons
3. composed of positive and negative ions held together by electrostatic attractions
4. composed of molecules held together by intermolecular dipole–dipole interactions
5. composed of molecules held together by intermolecular London forces
1. Fe(s)
2. KNO₃(s)
3. SiO₂(s)
4. HCl(s)

For questions 5 and 6 choose from the following.

1. an ionic solid
2. a metallic solid
3. a molecular solid containing nonpolar molecules
4. a covalent network solid
5. a molecular solid containing polar molecules
5. Diamond, C(s)
6. Solid sulfur dioxide, SO₂(s)
7. The approximate boiling points for hydrogen compounds of some elements in the nitrogen family are: (SbH₃ 15°C), (AsH₃ –62°C), (PH₃ –87°C), and (NH₃ –33°C). The best explanation for the fact that NH3 does not follow the trend of the other hydrogen compounds is
   1. NH₃ is the only one to exhibit hydrogen bonding
   2. NH₃ is the only one that is water-soluble
   3. NH₃ is the only one that is nearly ideal in the gas phase
   4. NH₃ is the only one that is a base
   5. NH₃ is the only one that is nonpolar
8. The critical point is
   1. the highest temperature and pressure where the substance may exist as discrete liquid and gas phases
   2. the temperature and pressure where the substance exists in equilibrium as solid, liquid, and gas phases
   3. the highest temperature and pressure where a substance can sublime
   4. the highest temperature and pressure where the substance may exist as discrete liquid and solid phases
   5. the highest temperature and pressure where the substance may exist as discrete solid and gas phases
9. For all one-component phase diagrams, choose the correct statement from the following list.
   1. The line separating the gas from the liquid phase may have a positive or negative slope.
   2. The line separating the solid from the liquid phase may have a positive or negative slope.
   3. The line separating the solid from the liquid phase has a positive slope.
   4. The temperature at the triple point is the same as at the freezing point.
   5. The triple point is at a pressure above 1 atm.

Choose the appropriate answer from the following list for questions 10 and 11.

1. London dispersion forces
2. covalent bonding
3. hydrogen bonding
4. metallic bonding
5. ionic bonding
10. This is the reason why argon may be solidified at a sufficiently low temperature.
11. This is the reason why diamond is so hard.
12. The triple point
    1. represents the highest pressure at which the liquid can exist
    2. is the lowest pressure at which the liquid can exist
    3. represents the lowest temperature at which the vapor can exist
    4. is 0.15 K higher than the melting point of the solid
    5. is at a pressure of 1 atm
13. A sample of a pure liquid is placed in an open container and heated to the boiling point. Which of the following may increase the boiling point of the liquid?
    1. The size of the container is increased.
    2. The container is sealed.
    3. A vacuum is created over the liquid.
    1. II and III
    2. and III
    3. III only
    4. II only
    5. I only
14. Which of the following best explains why 1-butanol, CH₃CH₂CH₂CH₂OH, has a higher surface tension than its isomer, diethyl ether, CH₃CH₂OCH₂CH₃?
    1. the higher density of 1-butanol
    2. the lower specific heat of 1-butanol
    3. the lack of hydrogen bonding in 1-butanol
    4. the higher molecular mass of 1-butanol
    5. the presence of hydrogen bonding in 1-butanol
15. Pick the answer that most likely represents the substances' relative solubilities in water.
    1. CH₃CH₂CH₂CH₃     <     CH₃CH₂CH₂OH     <     HOCH₂CH₂OH
    2. CH₃CH₂CH₂OH     <     CH₃CH₂CH₂CH₃     <     HOCH₂CH₂OH
    3. CH₃CH₂CH₂CH₃     <     HOCH₂CH₂OH     <     CH₃CH₂CH₂OH
    4. HOCH₂CH₂OH     <     CH₃CH₂CH₂OH     <     CH₃CH₂CH₂CH₃
    5. CH₃CH₂CH₂OH     <     HOCH₂CH₂OH     <     CH₃CH₂CH₂CH₃
16. What is the energy change that accompanies the conversion of molecules in the gas phase to a liquid?
    1. heat of condensation
    2. heat of deposition
    3. heat of sublimation
    4. heat of fusion
    5. heat of vaporization
17. Which of the following explains why the melting point of sodium chloride (NaCl 801°C) is lower than the melting point of calcium fluoride (CaF₂ 1423°C)?
    1. The chloride ion is smaller than the fluoride ion.
    2. The ratio of anions to cations is lower in sodium chloride.
    3. The charge on a sodium ion is less than the charge on a calcium ion.
    1. I and II
    2. I, II, and III
    3. III only
    4. II only
    5. I only
18. Which point on the diagram below might represent the normal melting point?



1. C
2. B
3. E
4. A
5. D



19. The above diagram represents the heating curve for a pure crystalline substance. The solid is the only phase present up to point
    1. C
    2. B
    3. E
    4. A
    5. D