Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question. You may use a
calculator to complete these problems.
|
| 1. | At
constant temperature, 14.0 L of O2 at 0.882 atm is compressed to 1.75 L. What is the final
pressure of O2? a. | 0.111 atm | b. | 0.142
atm | c. | 7.06
atm | d. | 21.6
atm | e. | 27.8
atm | | |
|
| 2. | If
the volume of a confined gas is quadrupled while its temperature remains constant, what change will
be observed? a. | The pressure of
the gas will decrease to 1/4 its original value. | b. | The pressure of
the gas will quadruple. | c. | The density of the gas will decrease to 1/2 its original
value. | d. | The average velocity of the molecules will
quadruple. | e. | The average velocity of the molecules will
double. | | |
|
| 3. | A
balloon is filled with He gas to a volume of 3.22 L at 32 °C. The balloon is placed in liquid nitrogen until its
temperature reaches -132 °C. Assuming the pressure remains constant, what is the volume of the
cooled balloon? a. | 0.628
L | b. | 0.781
L | c. | 1.24
L | d. | 1.49
L | e. | 6.96
L | | |
|
| 4. | Avogadro's hypothesis states that equal volumes of gases under the same conditions of
temperature and pressure have equal ____. a. | densities | b. | particle
velocities | c. | molar masses | d. | numbers of
particles | e. | masses | | |
|
| 5. | Which
of the following relationships are true for gases?
1. | The number of moles of a gas is directly proportional to its
volume (at constant pressure). | 2. | The pressure of a gas is inversely proportional to its
temperature in Kelvins (at constant volume). | 3. | The volume of a gas is directly proportional to its pressure
(at constant temperature). | | |
a. | 1
only | b. | 2
only | c. | 3
only | d. | 1 and
2 | e. | 2 and
3 | | |
|
| 6. | If
3.67 g CO2 gas is introduced into an evacuated 2.50 L flask at 65 °C, what is the
pressure inside the flask? (R = 0.08206 L·atm/mol·K) a. | 0.178
atm | b. | 0.445
atm | c. | 0.925
atm | d. | 40.7
atm | e. | 496
atm | | |
|
| 7. | A
mass of 1.663 g of an unknown gas is introduced into an evacuated 2.00 L flask. If the pressure in
the flask is 0.544 atm at 78 °C, which of the following gases might be in the flask? (R =
0.08206 L·atm/mol·K) a. | N2 | b. | C2H2 | c. | NH3 | d. | HCl | e. | N2O | | |
|
| 8. | What
volume of O2, measured at 91.2 °C and 743 mm Hg, will be produced by the decomposition of 4.88 g
KClO3? (R = 0.08206 L·atm/mol·K)
2 KClO3(s) ® 2 KCl(s) + 3 O2(g)
a. | 0.305
L | b. | 1.22
L | c. | 1.83
L | d. | 24.0
L | e. | 37.4
L | | |
|
| 9. | Ammonia gas is synthesized according to the balanced equation
below.
N2(g) + 3 H2(g) ® 2
NH3(g)
If 2.75 L N2 react with 7.75 L
H2, what is the theoretical yield (in liters) of NH3? Assume that the volumes
of reactants and products are measured at the same temperature and pressure. a. | 2.75
L | b. | 5.17
L | c. | 5.50
L | d. | 10.5
L | e. | 15.5
L | | |
|
| 10. | The
empirical formula of a certain hydrocarbon is CH2. When 0.120 mole of the hydrocarbon is
completely combusted with excess oxygen, 17.7 L CO2 gas is produced at 27 °C and 1.00 atm.
What is the molecular formula of the hydrocarbon? (R = 0.08206
L·atm/mol·K) a. | C2H2 | b. | C2H4 | c. | C3H6 | d. | C5H10 | e. | C6H12 | | |
|
| 11. | An
unknown gaseous hydrocarbon contains 85.63 % C. Its density is 0.426 g/L at 0.465 atm and 373 K. What
is the molecular formula of the gas? (R = 0.08206 L·atm/mol·K) a. | C2H4 | b. | C3H6 | c. | C4H8 | d. | C5H10 | e. | C6H12 | | |
|
| 12. | Carbon monoxide reacts with oxygen to form carbon dioxide.
2 CO(g) + O2(g) ® 2 CO2(g)
In a 1.00 L flask, 2.40 atm of CO reacts with 4.50 atm of
O2. Assuming that the temperature remains constant, what is the final pressure in the
flask? a. | 1.20
atm | b. | 2.40
atm | c. | 3.30
atm | d. | 3.60
atm | e. | 5.70
atm | | |
|
| 13. | A
mixture of He and O2 is placed in a 4.00 L flask at 32 °C. The partial
pressure of the He is 2.7 atm and the partial pressure of the O2 is 1.4 atm. What is the
mole fraction of O2? a. | 0.224 | b. | 0.341 | c. | 0.481 | d. | 0.518 | e. | 0.659 | | |
|
| 14. | Which
of the following are postulates of kinetic-molecular theory of gases?
1. | The distance between gas molecules is large in comparison to
their size. | 2. | Gas molecules are in constant, random
motion. | 3. | The kinetic
energy of gas particles is proportional to the Kelvin temperature. | | |
a. | 1 only | b. | 2
only | c. | 3
only | d. | 1 and
2 | e. | 1, 2, and
3 | | |
|
| 15. | What
is the root-mean-square velocity of ethane molecules (C2H6) at 273
K? a. | 15.0
m/s | b. | 47.2
m/s | c. | 275
m/s | d. | 476
m/s | e. | 652
m/s | | |
|
| 16. | Place
the following gases in order of increasing average velocity at 325 K: Ar, Ne, N2, and
SO2. a. | Ar < Ne <
N2 < SO2 | b. | Ne < Ar < N2 <
SO2 | c. | N2 < SO2 < Ne <
Ar | d. | SO2
< Ar < N2 < Ne | e. | Ar = Ne = N2 =
SO2 | | |
|
| 17. | The
average velocity of a gas molecule is a. | inversely proportional to its kinetic
energy. | b. | directly proportional to the gas constant,
R. | c. | directly proportional to the square root of its temperature in
K. | d. | inversely
proportional to the square of its mass. | e. | directly proportional to the square root of its
mass. | | |
|
| 18. | Carbon monoxide gas diffuses through a barrier at a rate of 0.480 mL/minute. If an
unknown gas diffuses through the same barrier at a rate of 0.277 mL/minute, what is the molar mass of
the gas? a. | 9.33
g/mol | b. | 21.3 g/mol | c. | 36.9
g/mol | d. | 44.01 g/mol | e. | 84.1
g/mol | | |
|
| 19. | Non-ideal behavior for a gas is most likely to be observed under conditions
of a. | high temperature
and low pressure. | b. | high temperature and high pressure. | c. | low temperature
and low pressure. | d. | standard temperature and pressure. | e. | low temperature
and high pressure. | | |
|
| 20. | One
way in which real gases differ from ideal gases is that the molecules of a real gas a. | are attracted to
each other. | b. | are liquids or solids above 273.15 K. | c. | are always
polar. | d. | move in circles rather than straight
paths. | e. | have no kinetic energy. | | |
|
| 21. | If
4.00 g S8 react with 4.25 L O2 at 39 °C and 1.00 atm, what is the maximum mass of SO3
produced? (R = 0.08206 L·atm/mol·K)
S8(s) + 12 O2(g) ® 8
SO3(g)
a. | 2.83 g | b. | 8.86
g | c. | 9.99
g | d. | 13.3
g | e. | 19.9
g | | |
|
| 22. | If a
gas effuses 1.618 times faster than Kr, what is its molar mass? a. | 18.02
g/mol | b. | 28.01 g/mol | c. | 32.01
g/mol | d. | 51.79 g/mol | e. | 65.88
g/mol | | |
|