Name: 
 

Intermolecular Forces


Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

 1. 
Which of the following statements concerning intermolecular forces are CORRECT?

1.
London dispersion forces exist in all molecular solids.
2.
Dipole-dipole attractions occur in all molecules that contain polar bonds.
3.
Hydrogen bonding only occurs for molecules containing OH bonds.
a.
1 only
b.
2 only
c.
3 only
d.
1 and 2
e.
1, 2, and 3
 

 2. 
Which one of the following substances will exhibit dipole-dipole intermolecular forces?
a.
C2H4
b.
SO2
c.
CO2
d.
F2
e.
Ar
 

 3. 
What intermolecular force or bond is primarily responsible for the solubility of H2S in water?
a.
ion-dipole force
b.
dipole-dipole force
c.
ionic bonding
d.
covalent bonding
e.
hydrogen bonding
 

 4. 
What intermolecular force or bond is primarily responsible for the solubility of chlorine (Cl2) in water?
a.
dipole/dipole force
b.
hydrogen bonding
c.
dipole/induced dipole force
d.
ion-dipole force
e.
ion-induced dipole force
 

 5. 
As molecular solids, which of the following will exhibit dipole-dipole intermolecular forces: PH3, SO3, Br2, and SiCl4?
a.
PH3 only
b.
PH3 and SO3
c.
SO3 and SiCl4
d.
Br2 and SiCl4
e.
PH3, SO3, and SiCl4
 

 6. 
Which of the following molecules will have the highest boiling point?
a.
H2
b.
CH4
c.
Ne
d.
Cl2
e.
O2
 

 7. 
Which one of the following molecules will have the lowest boiling point?
a.
CCl4
b.
CHCl3
c.
CH2Cl2
d.
CH3Cl
e.
CH4
 

 8. 
Arrange H2O, H2S, and H2Se in order from lowest to highest boiling point.
a.
H2O < H2S < H2Se
b.
H2O < H2Se < H2S
c.
H2S < H2Se < H2O
d.
H2S < H2O < H2Se
e.
H2Se < H2O < H2S
 

 9. 
Hydrogen bonding is present in all of the following molecular solids EXCEPT ____ .
a.
CH3OCH3
b.
H2O
c.
NH3
d.
HF
e.
H2O2
 

 10. 
Which of the following phase transitions is endothermic?
a.
gas to solid
b.
liquid to gas
c.
liquid to solid
d.
gas to liquid
e.
none of the above
 

 11. 
Which of the following statements are correct?
 
1.
Above the critical pressure, only the solid phase of a pure substance can exist.
2.
Above the critical temperature, a gas may not be condensed to a liquid.
3.
At the critical point, three phases (gas, liquid, and solid) may coexist at equilibrium.
a.
1 only
b.
2 only
c.
3 only
d.
1 and 2
e.
1 and 3
 

 12. 
Which of the following statements concerning the phase diagram below are CORRECT?

imforces-2_files/i0130000.jpg

1.
Moving from point B to A results in a phase transition from liquid to gas.
2.
Point D lies at the critical point.
3.
At point C, liquid and gas phases coexist at equilibrium.
a.
1 only
b.
2 only
c.
3 only
d.
1 and 3
e.
2 and 3
 

 13. 
An atom located on a face of a unit cell is shared equally between ____ unit cells.
a.
2
b.
4
c.
6
d.
8
e.
10
 

 14. 
Which equation represents the number of atoms in a body-centered cubic unit cell?
a.
# atoms = imforces-2_files/i0150000.jpg(8)
b.
# atoms = imforces-2_files/i0150001.jpg(8)
c.
# atoms = 1 + imforces-2_files/i0150002.jpg(8)
d.
# atoms = imforces-2_files/i0150003.jpg(6) + imforces-2_files/i0150004.jpg(8)
e.
# atoms = 1 + imforces-2_files/i0150005.jpg(6) + imforces-2_files/i0150006.jpg(8)
 

 15. 
If a metal crystallizes in a face-centered cubic lattice, each metal atom has ____ "nearest neighbors."
a.
6
b.
8
c.
10
d.
12
e.
16
 

 16. 
Cesium chloride forms a simple cubic crystal with chloride ions at the lattice points. The cesium ions occupy cubic holes. How many chloride ions surround each cesium ion in cesium chloride?
a.
1
b.
2
c.
4
d.
8
e.
12
 

 17. 
Arrange NaCl, HCl, CCl4, and GeCl4 in order of increasing boiling point.
a.
HCl < CCl4 < GeCl4 < NaCl
b.
HCl < GeCl4 < CCl4 < NaCl
c.
CCl4 < NaCl < HCl < GeCl4
d.
GeCl4 < NaCl < HCl < CCl4
e.
NaCl < GeCl4 < CCl4 < HCl
 

 18. 
Ammonia, NH3, is used as a refrigerant. At its boiling point of -33 °C, the enthalpy of vaporization of ammonia is 23.3 kJ/mol. How much heat is required to vaporize 355 g of ammonia at -33 °C?
a.
1.12 kJ
b.
152 kJ
c.
251 kJ
d.
486 kJ
e.
8.27 x 103 kJ
 

 19. 
At its boiling point of -42.1 °C, 14.6 kJ of heat is required to vaporize 33.9 g of propane (C3H8). What is the molar enthalpy of vaporization of propane?
a.
2.32 kJ/mol
b.
11.2 kJ/mol
c.
19.0 kJ/mol
d.
97.8 kJ/mol
e.
473 kJ/mol
 

 20. 
At 50.0 °C, water has an equilibrium vapor pressure of 92.5 mm Hg. If 4.700 g H2O is sealed in an evacuated 10.0-L flask and heated to 50.0 °C, what mass of H2O will evaporate? Assume any liquid remaining in the flask has a negligible volume. (R = 0.08206 L·atm/mol·K, 1 atm = 760 mm Hg)
a.
0.0459 g
b.
0.827 g
c.
1.21 g
d.
3.873 g
e.
4.700 g
 

 21. 
A phase diagram of a pure compound has a triple point at 27 °C and 65 mm Hg, a normal melting point at 24 °C, and a normal boiling point at 118 °C. Which of the following statements regarding this compound are CORRECT?

1.
The density of the solid is greater than that of the liquid.
2.
Sublimation occurs if the temperature of the solid phase is increased from 11 °C to 34 °C at a constant pressure of 61 mm Hg.
3.
Evaporation occurs if the pressure is raised from 65 mm Hg to 820 mm Hg at a constant temperature of 24 °C.
a.
1 only
b.
2 only
c.
3 only
d.
2 and 3
e.
1, 2, and 3
 

 22. 
The phase diagram for CO2 has a triple point at -56.6 °C and 5.19 atm, and a critical point at 31.0 °C and 73 atm. The solid and liquid phases are in equilibrium at -78.7 °C and 1.00 atm. Which of the following statements regarding CO2 are CORRECT?

1.
Sublimation occurs if the temperature of the solid phase is increased from -79.0 °C to 0.0 °C at a constant pressure of 2.5 atm.
2.
CO2 is a supercritical fluid at 55 °C and 75 atm.
3.
Condensation occurs if the pressure is decreased from 73 atm to 5.0 atm at 34 °C.
a.
1 only
b.
2 only
c.
3 only
d.
1 and 2
e.
1, 2, and 3
 

 23. 
Which statement about boiling point is FALSE?
a.
The boiling point is higher for compounds with strong intermolecular forces.
b.
The boiling point is higher for compounds with a high viscosity.
c.
The boiling point of a compound is an absolute constant.
d.
The boiling point of a compound is higher for nonvolatile compounds.
e.
All of the above statements are true.
 

 24. 
The rate of vaporization of a liquid can be increased by
      1.  increasing the surface area
      2.  increasing the temperature
      3.  decreasing the strength of the intermolecular forces
a.
1 only
b.
2 only
c.
3 only
d.
1 and 2 only 
e.
2 and 3 only
 

 25. 
Rank the compounds NH3, CH4, and PH3 in order of increasing boiling point.
a.
NH3 < CH4< PH3
b.
CH4< NH3 < PH3
c.
NH3 < PH3< CH4
d.
CH4 < PH3 < NH3
e.
PH3< NH33 < CH4
 



 
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