SCCH 161 Homework 5
1. The intermolecular forces present in CO include which of the following?
I. dipole-dipole
II. ion-dipole
III. dispersion
IV. hydrogen bonding
A. I, II, III, and IV
B. I and III
C. I, III, and IV
D. I and II
E. II and IV
2. Each of the following substances is a liquid at –50C. Place these liquids in order of
increasing vapor pressure: dimethyl ether (CH3OCH3), propane (C3H8), and ethanol
(CH3CH2OH).
A. ethanol < propane < dimethyl ether
B. ethanol < dimethyl ether < propane
C. propane < dimethyl ether < ethanol
D. dimethyl ether < ethanol < propane
E. propane < ethanol < dimethyl ether
3. The boiling points of propanol (CH3CH2CH2OH) and pentanol (CH3CH2CH2CH2CH2OH) are 97C
and 137C, respectively. The boiling point of butanol (CH3CH2CH2CH2OH) is predicted to be:
A. < 97C
B. > 137C
C. > 97C and < 137C
D. 97C
E. 137C
4. Which one of the following substances should exhibit hydrogen bonding in the liquid state?
A. PH3
B. He
C. H2S
D. CH4
E. CH3OH
5. Which of following can form hydrogen bonds with water molecules?
(1) Na+ (2) CH3COOH (3) C2H6 (4) CH3NH2
6. Each of the following substances is a gas at 25C and 1 atmosphere pressure. Which one will
liquefy most easily when compressed at a constant temperature?
A. F2
B. H2
C. HF
D. SiH4
E. Ar
7. Which one of the following substances crystallizes as a molecular solid?
A. KI
B. SiO2
C. Sn
D. CH3OH
E. Al2(SO4)3
8. Vanadium crystallizes in a body-centered cubic lattice, and the length of the edge of a unit
cell is 305 pm. What is the density of V? (MV =50.94 g/mol)
A. 5.96  10–30 g/cm3
B. 2.98  10–6 g/cm3
C. 2.98 g/cm3
D. 5.96 g/cm3
E. 11.9 g/cm3
9. A liquid boils when its
A. vapor pressure is exactly 1 atmosphere.
B. vapor pressure is equal to, or greater than, the external pressure pushing on it.
C. temperature is equal to 273 K (standard temperature).
D. temperature is greater than room temperature.
10. Use the graph of vapor pressure to determine the normal boiling point of CHCl 3.
A. 19C
B. 52C
C. 60C
D. 64C
E. 70C
11.
The vapor pressure of ethanol is 400 mmHg at 63.5C. Its molar heat of vaporization is
39.3 kJ/mol. What is the vapor pressure of ethanol, in mmHg, at 34.9C?
A. 0.0099 mmHg
B. 4.61 mmHg
C. 100 mmHg
D. 200 mmHg
E. 1,510 mmHg
12.
The molar heats of sublimation and fusion of iodine are 62.3 kJ/mol and15.3 kJ/mol,
respectively. Calculate the molar heat of vaporization of liquid iodine.
A. –77.6 kJ/mol
B. 47.0 kJ/mol
C. –47.0 kJ/mol
D. 77.6 kJ/mol
E. 4.07 kJ/mol
13.
Based on the phase diagram shown below, how will the melting point of the substance
change if the pressure is increased above 1 atm?
14.
Crystals of elemental sulfur are easily crushed, and melt at 113C. Liquid sulfur does not
conduct electricity. What kind of crystal is this?
A. Ionic Crystal
B. Covalent Crystal
C. Metallic Crystal
D. Molecular Crystal
E. Amorphous (Not a regular crystal)
15.
Polyethylene plastic consists of long chains of carbon atoms, each of which is also
bonded to hydrogens as shown below:
Water forms beads when placed on a polyethylene surface. Why?
A. Water is nonpolar and polyethylene is nonpolar. Therefore there is very little interaction
between these compounds. Accordingly, water beads are expected.
B. Water is highly polar and polyethylene is nonpolar. Therefore there is very little
interaction between these compounds. Accordingly, water beads are expected.
C. Water is highly polar and polyethylene is polar. Therefore there is very little interaction
between these compounds. Accordingly, water beads are expected.
D. Water is highly polar and polyethylene is ionic. Therefore there is very little interaction
between these compounds. Accordingly, water beads are expected.
16.
Select True or False: All intermolecular forces must be overcome in order for a
substance to undergo a phase change from a solid to a liquid.
17.
Which one of the following substances is expected to have the lowest melting point?
A. BrI
B. CsI
C. LiI
D. NaI
E. RbI
18.
Arrange the following substances in order of increasing boiling point: CH3OH, He, CH3Cl,
and Ar
A. CH3OH < He < CH3Cl < Ar
B. He < Ar < CH3OH < CH3Cl
C. Ar < He < CH3OH < CH3Cl
D. He < Ar < CH3Cl < CH3OH
E. CH3Cl < He < Ar < CH3OH
19.
Which of the following characteristics indicates the presence of weak intermolecular
forces in a liquid?
A. a low heat of vaporization
B. a high critical temperature
C. a low vapor pressure
D. a high boiling point
20.
Which of the following properties is not influenced by hydrogen bonding?
A. melting point
B. boiling point
C. vapor pressure
D. viscosity
E. flammability