5 Steps to a 5 AP Chemistry 2019

Solids, Liquids, and Intermolecular Forces ❮ 177

❯ Answers and Explanations

1. B—This answer describes a metallic solid.


2. C—This answer describes an ionic solid.


3. A—This answer describes a covalent network
   solid.


4. D—This answer describes a solid consisting of
   discrete polar molecules. Even though HCl(aq)
   is a strong acid with ions in solution, there is no
   water here to lead to ionization.


5. D—Each of the carbon atoms is covalently
   bonded to four other carbon atoms.


6. C—Sulfur dioxide exists as molecules that are
   polar.


7. A—Hydrogen bonding occurs when hydrogen is
   directly bonded to F, O, and in this case, N.


8. A—Argon is a noble gas; none of the other
   bonding choices is an option.


9. B—Diamond is a covalent network solid with
   many strong covalent bonds between the carbon
   atoms.


10. D—The size of the container and the number
    of moles are irrelevant. Sealing the container will
    cause an increase in pressure that will increase
    the boiling point. A decrease in pressure will
    lower the boiling point.
    11. D—The compound with the higher surface ten-
    sion is the one with the stronger intermolecular
    force. The –OH groups can form hydrogen
    bonds. The hydrogen bonding in 1-butanol is
    stronger than the dipole–dipole attractions in
    diethyl ether.
    12. C—Butane is nonpolar, whereas the other two
    compounds can form hydrogen bonds through
    the –OH groups. The more –OH groups, the
    more hydrogen bonding, and the more soluble
    in water (where hydrogen bonding also occurs).
    13. C—If the structures are similar and the inter-
    ionic distances are about the same, then the only
    factor remaining that will influence the lattice
    energy is the magnitude of the charges. The
    ionic charges are Li+, Cl-, Mg^2 +, O^2 - , Al^3 +, N^3 - ,
    Na+, and F-. The largest magnitude charges are
    in AlN, which will lead to the greatest attraction
    between the ions, as indicated by the highest lat-
    tice energy.


11. C—For ionic compounds, the key factors are the
    sizes and the charges on the ions. Smaller ions
    lead to higher melting points. Higher charges
    lead to higher melting points. Answer C deals
    with size; however, if this were the key factor,
    the melting point of sodium fluoride would be
    higher, which is not the case. This leads to C


12. Which of the following liquids will probably
    have the highest viscosity at a given temperature?
    (A) CH 3 CH 2 CH 2 OH
    (B) PCl 3
    (C) CCl 4
    (D) CH 3 CH 2 CH 2 CH 3


13. Most molecular species vaporize as simple mol-
    ecules. However, acetic acid, CH 3 COOH, is an
    exception. In the gaseous state, acetic acid mol-
    ecules exist as pairs known as dimers. What is the
    most probable cause of this behavior?
    (A) London dispersion forces
    (B) covalent bonding
    (C) hydrogen bonding
    (D) metallic bonding

A

B

C

D

E

F

Heat added

T

18. The above diagram represents the heating curve

for a pure crystalline substance. Both solid and

liquid are present in which region of the heating

curve?

(A) between points A and B

(B) between points B and C

(C) between points C and D

(D) between points D and E