1. If the pressure of a sample of gas with a constant number of moles ...

1. If the pressure of a sample of gas with a constant number of moles is quadrupled and the absolute temperature is doubled, by
what factor does the volume of the sample change
A. 8
B. 2
C. 1/2
D. 1/4
E. 1/8
nRT
V = after P is quadrupled and t is doubled we get:
P
nR ⋅ 2T
V = . Thus V is increased by 2/4 or 1/2.
4P
2. If the pressure on a sample of gas (constant number of moles) is tripled and the absolute temperature is quadrupled, by what
factor will the volume of the sample change
A. 12
B. 3/4
C. 4/3
D. 1/3
E. 4
nRT
V = after P tripled P and T is quadrupled, we get:
P
nR ⋅ 4T
V = . Thus V is increased by 4/3.
3P
3. A small bubble rises from the bottom of a lake, where the temperature and pressure are 4°C and 3.0 atm, to the water's
surface, where the temperature is 25°C and pressure is 0.95 atm. Calculate the final volume of the bubble if its initial volume
was 2.1 mL.
A. 0.72 mL
B. 6.2 mL
C. 7.1 mL
D. 22.4 mL
E. 41.4 mL
P V1
P2V2
(3.0 atm)(2.1mL) (0.95 atm)(V2
= nR = ⇒
= nR =
T T
277 K
298 K
1 )
1
V 2 = 7.1 mL
2
4. Calculate the volume occupied by 35.2 g of methane gas (CH 4 , 0=16.0 g/mol.) at 25°C and 1.0 atm.
(R = 0.0821 Latm/Kmol.)
A. 0.0186 L
B. 4.5 L
C. 11.2 L
D. 49.2 L
E. 53.7 L
1mol.
n = 35.2 g x = 2.19 mol.
16.0 g
nRT (2.19 mol.)(0.0821L ⋅ atm/mol ⋅ K)(298 K)
V = =
= 53.7 L
P
1atm
5. Calculate the density in g/L of chlorine gas at STP.
A. 2.13 x 10 -2 g/L
B. 46.9 g/L
C. 1.58 g/L
D. 3.16 g/L
E. 0.316 kg/L
RT (0.0821L ⋅ atm/mol ⋅ K)(273K)
n = =
= 0.0446 mol.
PV
(1atm)(1L)
70.9 g
mass = 0.0446 mol. x = 3.16 g d = 3.16 g / 1 L = 3.16 g/L
1mol.
6. Which of the following gases will have the greatest density when they are all compared at the same temperature and
pressure
A. H 2
If they are all at the same temperature and pressure, then the moles per liter will also be the
B. CClF 3
same for all the gases. Consequently, the gas with the greatest density (g/L) will be the gas
C. CO 2
D. C 2 H 6
with the greatest molar mass, which is CClF 3
E. CF 4

7. Two moles of chlorine gas at 20.0°C are heated to 350°C while the volume is kept constant. The density of the gas
A. increases.
Density is g/L. Since both moles (thus mass) and the volume are constant, the density
B. decreases.
must also be constant.
C. remains the same.
D. not enough information given to correctly answer the question
8. A sample of unknown gas weighing 5.02 g is sealed in a 1.0 L flask at 37°C and 3.75 atm. Which one of the following is
most likely to be the unknown
mol.
A. H 2 O
RT (0.0821L ⋅atm/mol
⋅ K)(310 K)
B. HBr
n = =
= 0.147
PV (3.75 atm)(1L)
C. HCN
E. C 2 H 2
D. H 2 S
0 = 5.02 g / 0.147 mol. = 34.1 g/mol. This is the molar mass of H 2 S.
9. A mixture of three gases has a total pressure of 1,380 mmHg at 298 K. The mixture is analyzed and is found to contain 1.27
mol CO 2 , 3.04 mol CO, and 1.50 mol Ar. What is the partial pressure of Ar
A. 0.258 atm
B. 301 mmHg
C. 356 mmHg
D. 5,345 mmHg
E. 8,020 mmHg
χ
mol.
=
mol.
1.
50
=
1.27 + 3.04 + 1.50
Ar
Ar
=
total
0.258
P Ar = χ Ar·PT = (0.258)(1380 mmHg) = 356 mmHg
10. What volume of oxygen gas at 320 K and 680 torr will react with 2.50 L of NO gas at the same temperature and pressure
2NO(g) + O 2 (g) → 2NO 2 (g)
A. 1.25 L
B. 2.50 L
C. 3.00 L
D. 1.00 L
E. 5.00 L
n
RT V
= =
P n
VNO
O2 O2
NO
VO 2
=
1.25 L
O2
2.50 L V
⇒ =
2 mol. 1mol.
11. What mass of KClO 3 (0 = 122 g/mol.) must be decomposed to produce 126 L of oxygen gas at 133°C and 0.880 atm
2KClO 3 (s) → 2KCl (s) + 3O 2 (g)
A. 24.6 g
B. 70.8 g
C. 272 g
D. 408 g
E. 612 g
RT (0.0821L ⋅atm/mol
⋅K)(406 K)
n = =
= 3.33 mol.O 2
PV (0.880 atm)(126 L)
2 mol. KClO3
122 g
3.33 mol.O 2 x
x = 272 g KClO3
3 mol.O 1mol.
2
12. If equal masses of O 2 (g) and HBr (g) are in separate containers of equal volume and temperature, which one of the following
statements is true
A. The pressure in the O 2 container is greater than that in the HBr container.
B. There are more HBr molecules than O 2 molecules.
C. The average kinetic energy of O 2 molecules is greater than that of HBr molecules.
D. The average kinetic energy of HBr molecules is greater than that of O 2 molecules.
E. The pressures of both gases are the same.
P
n
O2
O2
RT P
= =
V n
HBr
HBr
Since there are equal masses of each gas, there must be more moles of O 2 than HBr, which
means that the pressure of the O 2 must also be greater.

13. Which gas has molecules with the greatest average molecular speed at 25°C
A. CH 4
B. Kr
C. N 2
D. CO 2
E. Ar
Kinetic energy will be the same for all molecules since they are at the same temperature.
Since kinetic energy = ½(mass)(speed) 2 , lighter molecules must have greater speeds.
14. In which of the following gases do molecules have the highest average kinetic energy at 25°C
A. H 2
B. O 2
C. N 2
D. Cl 2
E. all have the same
Kinetic energy is the same for all molecules at the same temperature.
15. For a substance that remains a gas under the conditions listed, deviation from the ideal gas law would be most pronounced at
A. 100°C and 2.0 atm.
B. 0°C and 2.0 atm.
C. -100°C and 2.0 atm.
D. -100°C and 4.0 atm.
E. 100°C and 4.0 atm.
Gases deviate from ideal behavior at lower temperatures and higher pressures since
IMF's and molecular (and atomic) volumes become significant.
16. Helium atoms do not combine to form He 2 molecules, yet He atoms do attract one another weakly through
A. dipole-dipole forces.
B. ion-dipole forces.
C. dispersion forces.
D. dipole-induced dipole forces.
E. hydrogen bonding.
17. Which one of the following substances should exhibit hydrogen bonding in the liquid state
A. PH 3
B. H 2
C. H 2 S
D. CH 4
E. NH 3
Hydrogen bonding requires H bonded to either N, O or F.
18. Which of the following should have the highest boiling point
A. CH 4
All the molecules have dispersion forces; only CH 3 Cl has dipole interactions as well.
B. Cl 2
Thus CH
C. Kr
3 Cl will have the strongest intermolecular forces and the highest boiling point.
D. CH 3 Cl
E. N 2
19. Which of the following liquids would have the highest viscosity at the same temperature
A. CH 3 OCH 3
B. CH 2 Cl 2
C. C 2 H 5 OH
D. CH 3 Br
E. HOCH 2 CH 2 OH
All the molecules have dispersion and dipoles forces. In addition, C 2 H 5 OH and
HOCH 2 CH 2 OH have hydrogen bonding. HOCH 2 CH 2 OH is capable of hydrogen
bonding through both OH groups and will thus have the strongest intermolecular forces
and the highest viscosity.

20. Each of the following substances is a liquid at -50°C. Place these liquids in order of increasing vapor pressure.
H H
H H
H H H
H C O C H H C C OH H C C C
H H
H H
H H H
dimethyl ether ethanol propane
H
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
Vapor pressure depends on the facility by which a molecule can leave the
liquid and become a gas. The more easily this occurs, the higher the
resulting vapor pressure. For this process to be facile, the intermolecular
forces must be weak. Propane, with only dispersion forces, will have the
weakest IMF's. Ethanol, with H-bonding, will have the strongest IMF's.
21. Arrange the following in order of increasing boiling point: RbCl, CH 3 Cl, CH 3 OH, CH 4 .
A. CH 3 OH < CH 3 Cl < RbCl < CH 4
B. CH 3 OH < CH 4 < CH 3 Cl < RbCl
C. RbCl < CH 3 Cl < CH 3 OH < CH 4
D. CH 4 < CH 3 OH < CH 3 Cl < RbCl
E. CH 4 < CH 3 Cl < CH 3 OH < RbCl
RbCl is an ionic solid and would consequently have a higher boiling point than
the three molecular solids. The three would be ordered by IMF's.
CH 3 OH: H-bonding, dipole, dispersion
CH 3 Cl: dipole, dispersion
CH 4 : dispersion
22. Which one of the following substances would exhibit hydrogen bonding in the liquid state
A. SiH 4
B. H 2
C. H 2 S
D. CH 4
E. CH 3 NH 2
Hydrogen bonding requires H bonded to either N, O or F.
23. Which one of the following crystallizes in a metallic lattice
A. C (graphite)
B. NaMnO 4
C. K As the only metal, K will crystallize in a metallic lattice
D. LiClO 4
E. K 2 Cr 2 O 7
24. 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.
25. Which of the following is not an endothermic process
A. melting of a solid
B. vaporization
C. raising the temperature of a gas
D. condensation of water vapor
E. sublimation of dry ice
All the processes except for condensation require that energy be put into
the system, that heat be added, and are thus endothermic. Only
condensation give off energy (put another way: is facilitated by cooling)
and is therefore exothermic.

B
(s)
(")
P (mm Hg)
(g)
90
A
28
27
75
114
T (°C)
535
26. In the phase diagram of I 2 , the point represented by A is the
A. boiling point.
B. critical point.
C. melting point.
D. sublimation point.
E. triple point.
27. What is the phase of I 2 at 80 mmHg and 200°C
A. gas
B. liquid
C. solid
D. super critical fluid
E. Bose-Einstein condensate
28. If I 2 at 85 mmHg and 150°C is cooled to 75°C (still 85 mmHg), what phase change would occur
A. Condensation
B. Deposition
C. Freezing
D. Sublimation
E. No phase change would occur.

temperature
2 3
4
5
1
time
29. The graph above represents the heating of a piece of solid potassium over time. The region labeled 2 represents
A. vaporization of the liquid phase.
B. heating of the solid phase.
C. heating of the liquid phase.
D. heating of the gas phase.
E. melting of the solid phase.
30. The graph above represents the heating of a piece of solid potassium over time. The region labeled 5 represents
A. vaporization of the liquid phase.
B. heating of the solid phase.
C. heating of the liquid phase.
D. heating of the gas phase.
E. melting of the solid phase.