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Review Topic 10: Gases and the Kinetic Molecular Theory
Name: Score: 30 / 30 points (100%)
Review Topic 10: Gases and the Kinetic Molecular Theory
Multiple Choice
Identify the choice that best completes the statement or answers the question.
C 1. a.
b.
C 2. D 3. c.
d.
ANSWER: C
I see an R value so PV=nRT
(400)(V)=(4)(8.31)(300)
V = 24.93
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a.
c.
b.
d.
ANSWER: C
Total = partial pressures
523.8 = 23.8 + x
x = 500
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a.
b.
c.
d.
ANSWER: D
higher kinetic energy = higher temperature
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B 4. A 5. Review Topic 10: Gases and the Kinetic Molecular Theory
(b = 100 °C)
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a.
c.
b.
d.
ANSWER: B
both increase
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a.
b.
A 6. c.
d.
ANSWER: A
CO2 has a molar mass of 44 g/mol (12+16*2)
A gas at STP has a volume of 22.4 L/mol
44g/22.4L = 1.96g/L
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a.
c.
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Review Topic 10: Gases and the Kinetic Molecular Theory
b.
d.
ANSWER: A
It’s the gas that pushes the liquid in the side tube up the highest
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A 7. The gas with the largest volume at STP is —
a. 10.0 g He
c. 10.0 g Ar
b. 10.0 g Ne
d. 10.0 g Kr
ANSWER: A
Turn to moles then multiply by 22.4
10/4 = 2.5x22.4 = 56 L
10/20 = 0.5x22.4 = 11.2 L
10/39.9 = 0.25x22.4 = 5.6 L
10/83.80 = 0.11 x 22.4 = 2.67 L
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D 8. According to Charles’ law, the volume of a fixed amount of gas is directly
proportional to —
a. isoelectric mixture
c. barometric pressure
b. vapor concentration
d. Kelvin temperature
ANSWER: D
Charles’ law is volume and temperature
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A 9. Industrial deep­sea divers must breathe a mixture of helium and oxygen to prevent a
disorienting condition known as nitrogen narcosis. If a diver’s tank is filled with a
helium­oxygen mixture to a pressure of 170 atmospheres and the partial pressure of
helium is 110 atmospheres, the partial pressure of the oxygen is —
a. 60 atm
c. 140 atm
b. 110 atm
d. 280 atm
B 10. ANSWER: A
total = partial pressures
170 = 110 + x
x = 60
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Review Topic 10: Gases and the Kinetic Molecular Theory
a. 7.87 L
b. 9.45 L
c. 10.2 L
d. 10.6 L
ANSWER: B
chart problem
1
2
? = P
98.7
102.7
T (Kelvin)
278
273
V
10
?
= 9.44
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A 11. a. decreases the pressure by 80 kPa
b. decreases the pressure by 160 kPa
D 12. c. increases the pressure by 80 kPa
d. increases the pressure by 160 kPa
ANSWER: A
100 mL = ~250 kPa
150 mL = ~175 kPa
~75 kPa and it decreased from 250 to 175
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Review Topic 10: Gases and the Kinetic Molecular Theory
a.
b.
c.
d.
The gas in balloon A is under less pressure.
The gas in balloon A is warmer.
The gas in balloon B is under more pressure.
The gas in balloon B is warmer.
ANSWER: D
a ­ A would be bigger
b ­ A would be bigger
c ­ B would be smaller
d ­ B would be bigger
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Review Topic 10: Gases and the Kinetic Molecular Theory
a.
c.
b.
d.
ANSWER: C
Looking at line D at 70 kPa, it would be slightly more than 90°C
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A 14. If 6 liters of hydrogen gas are used, how many liters of nitrogen gas will be needed for
the above reaction at STP?
a. 2 liters
c. 4 liters
b. 3 liters
d. 12 liters
ANSWER: A
6L H2 x = 2L N2
coefficients
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B 15. According to Boyle’s law, the relationship between the pressure and volume of a gas
at constant temperature is —
a. numerically equivalent
c. positively correlated
b. inversely proportional
d. totally unrelated
ANSWER: B
Pressure goes up, volume goes down. That is inverse.
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B 16. Charles’ Law states that if a given quantity of gas is held at a constant pressure, then
its volume is directly proportional to the absolute temperature. This law explains why
—
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Review Topic 10: Gases and the Kinetic Molecular Theory
a.
b.
c.
d.
the pressure of a gas increases when volume decreases
a gas­filled balloon expands when it is heated
solids require heat in order to change into gases
some gases only react with each other at high temperatures
ANSWER: B
As temperature goes up, volume goes up ­ this is stated in B
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A 17. The total pressure of an O2­Ar­He gas mixture is 755 mmHg. If the partial
pressure of Ar is 174 mmHg and the partial pressure of He is 389 mmHg,
then the partial pressure of O2 is —
a. 192 mmHg
c. 366 mmHg
b. 282 mmHg
d. 563 mmHg
ANSWER: A
Total = partial pressures
755 = 174 + 389 + x
x = 192
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B 18. A mixture of gases with a pressure of 800.0 mm Hg contains 60% nitrogen and 40%
oxygen by volume. What is the partial pressure of oxygen in this mixture?
a. 140.0 mm Hg
c. 373.0 mm Hg
b. 320.0 mm Hg
d. 480.0 mm Hg
ANSWER: B
40% of 800 = 0.40x800 = 320
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D 19. Which of these statement describes what happens to the molecules of a solid as the
temperature is lowered to absolute zero (­273ºC)?
a. They begin to take up more space.
b. They become farther apart.
c. Their kinetic energy gradually increases to a maximum.
d. Their motion gradually decreases and eventually stops.
ANSWER: D
temperature = kinetic energy = motion
so if temperature goes to 0 so would motion
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B 20. According to the kinetic­molecular theory of gases, molecules of an ideal gas ­­
a. travel in curved lines of motion
c. are separated by small distances
b. undergo elastic collisions
d. have strong forces between them
ANSWER: B
a ­ not true ­ assumes straight lines
b ­ true
c ­ not true ­ assumes large distances compared to the size of the molecules
d ­ not true ­ assumes no attraction between molecules
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Review Topic 10: Gases and the Kinetic Molecular Theory
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B 21. The partial pressures of the gases that comprise air are shown in the table.
If the total atmospheric pressure is 760.00 mm Hg, what is the partial pressure of
CO2?
a. 0.03 mm Hg
c. 7.36 mm Hg
b. 0.24 mm Hg
d. 759.76 mm Hg
A ANSWER: B
760 = 7.1 + x + 593.44 + 159.20 + 0.02
x = 0.24
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22. Which graph shows the relationship between temperature and volume as described in
the Charles’ Law?
a. Graph A
b. Graph B
c. Graph C
d. Graph D
ANSWER: A
Charles’ Law ­ As temperature increase, volume increases ­ Graph A
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Review Topic 10: Gases and the Kinetic Molecular Theory
B 23. A gas cylinder with a volume of 3.00 dm3 contains 8.00 moles of oxygen gas at a
temperature of 50.0 K. What is the pressure inside the cylinder?
a. 504 kPa
c. 2220 kPa
b. 1110 kPa
d. 3320 kPa
ANSWER: B
I see an R value so I think PV=nRT
P(3.00) = (8.00)(8.31)(50)
P=1108
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A 24. How many liters of oxygen are required to produce 2 liters of water at STP?
a. 1
c. 3
b. 2
d. 4
ANSWER: A
This is a Gay­Lussac’s 2nd gas Law Problem ­ coefficients equal relative
number of moles
2L x = 1L O2
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B 25. A tank contains N2 at 1.0 atm and O2 at 2.0 atm. Helium is added to this tank until the
total pressure is 6.0 atm. What is the partial pressure of the helium?
a. 4.0 atm
c. 2.0 atm
b. 3.0 atm
d. 1.0 atm
ANSWER: B
Total = all the partial pressures
6.0 = 1.0 + 2.0 + x
x = 3.0
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B 26. One of the main assumptions of the kinetic molecular theory of gases is that the
particles of an ideal gas —
a. must be single atoms instead of molecules
b. are in constant motion
c. must be maintained at very high pressures
d. must be highly chemically reactive
ANSWER: B
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Review Topic 10: Gases and the Kinetic Molecular Theory
kinetic molecular theory = moving molecule theory
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B 27. What change in volume occurs for 50 mL of a gas in a sealed container if the pressure
is doubled?
a. Increase by a factor of 400
c. Increases by a factor of 4
b. Decreases by a factor of 2
d. Decreases by a factor of 25
ANSWER: B
Pressure and volume are inversely proportional so when the one goes up, the
other will go down in a similar fashion. So if we double one; we will half the
other.
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D 28. Which of the following liquids would exhibit the highest vapor pressure at 25.0 °C?
a. Water, boiling point 100 °C
c. Ethyl alcohol, boiling point 78.3 °C
b. Glycerine, boiling point 290 °C
d. Ether, boiling point 34.6 °C
ANSWER: D
It has the closest boiling point to the given temperature. The closer you are to
the boiling point, the more vapor pressure you would have.
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D 29. Increasing the volume of a sealed container will cause the gas particles within the container
to ­
a. form a liquid
c. increase in molecular attraction
b. collide more frequently
d. exhibit lower pressure
ANSWER: D
By increasing the volume, you are giving the molecules more room, therefore:
form a liquid ­ incorrect, you would have to force the gas particles together to
make them turn into a liquid
collide more frequently ­ incorrect, you gave them more room so they will
collide less frequently
increase in molecular attraction ­ incorrect, you gave them more space so they
will have less opportunity to be attracted to each other
exhibit lower pressure ­ correct, and this follows Boyle’s law, as volume
increases, pressure decreases
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Numeric Response
Directions: Type your answer in the box.
30. An expandable container of oxygen gas has a volume of 125 mL at a temperature of
25.0°C. What volume (in mL) will the gas occupy at 55.0°C?
RESPONSE: 137.6
ANSWER: 137.6
Acceptable answers are: 130, 130., 137, 137., 137.5, 137.6, 138, 138., 140,
or 140.
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Review Topic 10: Gases and the Kinetic Molecular Theory
First, we need the temperature in Kelvin (+273) for this problem. Then, you
can either use the PTV trick I have shown you in class (and below) or you
can use the formula V1/T1=V2/T2.
=137.6
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