3U-gases-prac-test
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
1. Which of the following is NOT a characteristic of a gas at STP?
a. high rate of diffusion
d. highly defined shape
b. high compressibility
e. high level of translational motion
c. high fluidity
____
2. Pure oxygen boils at –183ºC and freezes at –219ºC. What state will the oxygen be in if the temperature is
brought to within 50 K of absolute zero?
a. solid
d. plasma
b. liquid
e. solution
c. gas
____
3. At a fixed temperature and pressure, the average distance between molecules would be greater in a sample of
a. air
d. NaCl
b. concrete
e. liquid perfume
c. sponge
____
4. The random motion of gas molecules is a significant part of the explanation for the
a. low density of gases
b. transparency of gases
c. high compressibility of gases
d. low reactivity of gases
e. the reason why gases always fill their containers over time
____
5. Welders use two types of compressed gases to produce very high temperatures to cut or weld metals. What
are the two gases used by welders to accomplish this?
a. oxygen and hydrogen
d. propane and oxygen
b. methane and oxygen
e. acetylene and hydrogen
c. acetylene and oxygen
____
6. A sample of a gas with a volume of 1 L at 25ºC and a pressure of 101.325 kPa is subjected to an increase in
pressure and a decrease in temperature. The volume of the gas will
a. decrease
b. increase
c. remain the same
d. become zero
e. either increase or decrease, depending on the magnitude of the pressure and temperature
changes
____
7. Under conditions of constant temperature and amount of molecules, Boyle's law requires that
(i) P1V1 = P2V2
(ii) PV = constant
(iii)
a. (i) only
b. (ii) only
c. (iii) only
d. (i), (ii), and (iii)
e. none of the above
2
____
8. What pressure would be exerted by 76.0 g of fluorine gas in a flask with a volume of 1.50 L at a temperature
of –37ºC?
a. 2.61  103 kPa
d. 8511 kPa
b. 415 kPa
e. 831 kPa
c. 1.98  106 kPa
____
9. For a gas, which pair of variables are inversely proportional to one another if all other conditions remain
constant?
a. P and T
d. n and V
b. P and V
e. n and P
c. V and T
____ 10. Which of the following is NOT an observed property of gases?
a. Gases are compressible and can liquefy under pressure.
b. Gases have variable shape and volume.
c. Gases expand to fill their container.
d. Gases have a density greater than 1.00 g/mol.
e. Gases diffuse and are completely miscible.
____ 11. Which of the following express standard atmospheric pressure?
a. 125 kPa
d. 96.7 kPa
b. 100 atm
e. 10.0 atm
c. 1.00 atm
____ 12. Which of the following changes increases the pressure in a gaseous system?
a. Increasing the volume occupied by the gas.
b. Decreasing the temperature of the gas.
c. Increasing the number of gas molecules within the system.
d. all of the above
e. none of the above
____ 13. Which of the following graphs represents the plot of pressure versus volume at constant temperature?
a. A
b. B
c. C
d. D
e. E
____ 14. Laughing gas, N2O, and tear gas, NH3, are released at the same time at an equal distance away from you.
Particles of laughing gas and tear gas move by simple diffusion and each molecule has the same kinetic
energy. The room is perfectly sealed with no prevalent air current. Would you laugh or cry first?
a.
b.
c.
d.
You would laugh first.
You would cry first.
You would laugh and cry at the same time.
You would do neither because the gases would neutralize each other before reaching you.
3
e. This is impossible to determine because too many variables are not controlled.
____ 15. The temperature of a gas remains constant while the volume of a given amount of gas is tripled. What will
happen to the pressure reading compared to the initial pressure?
a. No change in pressure will be recorded.
b. The final pressure will be three times that of the initial pressure.
c. The final pressure will be one-third greater than the initial pressure.
d. The final pressure will be one-third the value of the initial pressure.
e. The final pressure will decrease by one-third from the initial pressure.
____ 16. At a constant pressure, a 10.0-L volume of gas is cooled from 546 K to 273 K. What will the final volume of
this gas be assuming no liquefying occurs.
a. 10.0 L
d. 20.0 L
b. 2.00 L
e. 5.00 L
c. 8.00 L
____ 17. For any confined ideal gas, when the temperature is increased and the volume is decreased at the same time,
the
a. molecules move more slowly
d. pressure stays constant
b. average kinetic energy is decreased
e. pressure increases
c. number of collisions is decreased
____ 18. A mixture of 90.0 g of methane gas, CH4, and 10.0 g of Ar has a total pressure of 250 mm Hg under
conditions of constant temperature and volume. Determine the partial pressure of CH4.
a. 143 mm Hg
d. 239 mm Hg
b. 100 mm Hg
e. 26.6 mm Hg
c. 10.7 mm Hg
____ 19. The number of molecules in 1.00 L of O2 gas at STP is
a. the same as the number of molecules in 1.00 L of H2 gas at STP
b. 16 times the number of molecules in 1.00 L of H2 at STP
c.
times the number of molecules in 1.00 L of H at STP
2
d. 6.02  1023
e. variable due to the porosity of the container
____ 20. You have 10.0 g of hydrogen gas in a closed container. You heat the flask from 273 K to 546 K and reweigh
the flask. The new reading on the scale will read
a. 0.0916 g
d. 20.0 g
b. 5.0 g
e. variable reading due to density in gas
c. 10.0 g
____ 21. Equal masses of hydrogen and oxygen gases are placed into a container that is then tightly stoppered. Which
of the following statements about the system is true?
a. There are more hydrogen molecules than oxygen molecules.
b. All of the molecules have the same velocity.
c. Both gases exert the same partial pressure.
d. All of the molecules strike the walls with the same force.
e. There are more oxygen atoms than hydrogen atoms in the container.
____ 22. A rigid container contains 2.50 mol O2, 0.50 mol N2, and 1.00 mol CO2. The total pressure of the system is
200 kPa. The partial pressure exerted by the N2 in the mixture is
a. 25.0 kPa
d. 125 kPa
4
b. 50.0 kPa
c. 100 kPa
e. 150 kPa
Short Answer
23. Rank the following states of matter on their fluidity, from the most fluid to the least fluid:
(a) solid
(b) liquid
(c) gas
24. Solve for the missing variable in the following chart:
V1
V2
T1
T2
L
125 L
450 K
373 K
25. Determine the value for a new universal gas constant if 1.00 mol of N2 occupies a volume of 22.4 L at 273 K
and 760 mm Hg.
26. What would the net effect on the volume of an ideal gas be if the absolute temperature is decreased by onehalf and the pressure is doubled?
27. Propane is used as the fuel for barbeques. What volume of oxygen would be required to completely burn 2 L
of propane, C3H8, and produce CO2 and H2O?
28. Hydrofluoroether is a promising alternative to CFCs. What common type of natural material would also act as
an excellent coolant, is readily available, has zero ozone depletion factor, and would have a negligible effect
on greenhouse gases?
Problem
29. What is the initial pressure of a gas if it occupied a volume of 375 mL, but now occupies a volume of 1.25 L
at a pressure of 95.5 kPa. Assume that the temperature remains constant throughout the process.
30. A balloon filled with helium gas has a volume of 5.80 L measured at 101.325 kPa and is placed into a
hyperbaric chamber at a pressure of 1255 mm of Hg. What will the new volume be if the temperature remains
constant throughout the process?
31. Determine the number of moles of neon gas contained in a 5.25-L gas tank at 105 kPa and a temperature of
299 K. If the gas is nitrogen instead of neon, will the answer be the same? Explain your reasoning.
32. A balloon is brought to the top of Mt. Logan where it occupies a volume of 775 mL at a temperature of –28ºC
and a pressure of 92.5 kPa. What is the pressure at the bottom of the mountain if the same balloon has a
volume of 825 mL at a temperature of 15ºC?
33. A pressure reading of 275 kPa is found when the temperature of air in a piston is 35ºC and the volume is 2.5
L. What will the temperature reading be, in degrees Celsius, if the volume doubles and the pressure becomes
100 kPa?
5
34. A balloon has been filled with He gas to a volume of 10.0 L at STP conditions. The volume can increase by
another 12% before the balloon will burst. Will the balloon burst if it is brought outside where conditions are
at SATP? Show all of your work to justify your answer.
35. A fire extinguisher filled with carbon dioxide has a mass of 3500 g. After releasing all of the CO2, the mass of
the extinguisher is 2735 g. What was the pressure reading on the gauge before any CO2 was released, if the
volume of the extinguisher is 4.25 L and it is stored at a temperature of 25ºC?
36. Determine the volume of a balloon filled with 4.25 mol of He gas when the atmospheric pressure is 92.7 kPa
and the temperature is 30ºC.
37. Acetylene is burned in the presence of oxygen gas during the welding process according to the following
balanced chemical equation: 2C2H2 (g) + 5O2 (g)  2H2O (g) + 4CO2 (g)
If you have 40 L of acetylene at STP, what volume of oxygen gas will you need at STP to completely burn
the acetylene?
38. Black gunpowder stored in a barrel has been ignited and 1245 g of KNO3 (s) are found in the exploding
mixture. What will the total volume be of all the gases produced in this explosion at a temperature of 350ºC
and a pressure of 2000 kPa?
KNO3 (s) + C(s) + S8 (s)  N2 (g) + CO2 (g) + K2S(s)
6
3U-gases-prac-test
Answer Section
MULTIPLE CHOICE
1. ANS:
STA:
2. ANS:
STA:
3. ANS:
STA:
4. ANS:
STA:
5. ANS:
STA:
6. ANS:
STA:
7. ANS:
STA:
8. ANS:
STA:
9. ANS:
STA:
10. ANS:
STA:
11. ANS:
STA:
12. ANS:
STA:
13. ANS:
STA:
14. ANS:
STA:
15. ANS:
STA:
16. ANS:
STA:
17. ANS:
STA:
18. ANS:
STA:
19. ANS:
STA:
20. ANS:
STA:
21. ANS:
STA:
22. ANS:
STA:
D
GA1.02
A
GA2.02
A
GA1.01
E
GA1.02
C
GA3.03
A
GA1.03
E
GA1.03
A
GA2.04
B
GA1.03
D
GA1.02
C
GA2.01
C
GA1.04
E
GA2.03
B
GA3.04
D
GA1.04
E
GA1.04
E
GA1.03
D
GA2.04
A
GA1.04
C
GA1.02
A
GA1.04
A
GA1.04
PTS: 1
REF: K/U
OBJ: 9.1
PTS: 1
REF: I
OBJ: 9.2
PTS: 1
REF: K/U
OBJ: 9.1
PTS: 1
REF: K/U
OBJ: 9.1
PTS: 1
REF: MC
OBJ: 9.3
PTS: 1
REF: K/U
OBJ: 9.2
PTS: 1
REF: K/U
OBJ: 9.2
PTS: 1
REF: I
OBJ: 9.4
PTS: 1
REF: K/U
OBJ: 9.2
PTS: 1
REF: K/U
OBJ: 9.1
PTS: 1
REF: I
OBJ: 9.2
PTS: 1
REF: K/U
OBJ: 9.2
PTS: 1
REF: I
OBJ: 9.2
PTS: 1
REF: MC
OBJ: 9.2
PTS: 1
REF: K/U
OBJ: 9.2
PTS: 1
REF: K/U
OBJ: 9.2
PTS: 1
REF: K/U
OBJ: 9.2
PTS: 1
REF: C
OBJ: 10.1
PTS: 1
REF: K/U
OBJ: 10.2
PTS: 1
REF: K/U
OBJ: 10.2
PTS: 1
REF: K/U
OBJ: 10.2
PTS: 1
REF: K/U
OBJ: 10.1
7
SHORT ANSWER
23. ANS:
gas, liquid, solid
PTS: 1
24. ANS:
REF: K/U
OBJ: 9.1
STA: GA1.01
PTS: 1
25. ANS:
P = 760 mm Hg
V = 22.4 L
n = 1.00 mol
T = 273 K
R=?
REF: I
OBJ: 9.2
STA: GA2.04
PTS: 1
26. ANS:
REF: I
OBJ: 9.4
STA: GA2.04
Both of these changes are negative growth factors, hence, the volume of the gas will be reduced to
original volume.
PTS: 1
REF: K/U
27. ANS:
C3H8 + 5O2  3CO2 + 4H2O
OBJ: 9.2
STA: GA1.03
PTS: 1
28. ANS:
OBJ: 10.2
STA: GA2.01
REF: I
of its
8
hydrocarbons such as propane, pentane, isobutane, or cyclopentane
PTS: 1
REF: MC
OBJ: 10.2
STA: GA3.01
OBJ: 9.2
STA: GA2.04
PROBLEM
29. ANS:
V1 = 375 mL
P2 = 95.5 kPa
V2 = 1.25 L
P1 = ?
Convert mL to L for V1:
The pressure of the gas was 318 kPa.
PTS: 1
REF: I
30. ANS:
P1 = 101.325 kPa
V1 = 5.80 L
P2 = 1255 mm of Hg
V2 = ?
Convert P2 to kPa unit:
The new volume of the balloon will be 3.51 L.
PTS: 1
31. ANS:
V = 5.25 L
REF: I
OBJ: 9.2
STA: GA2.04
9
P = 105 kPa
T = 299 K
R = 8.31 kPa L/mol K
n=?
The answer would be the same if the question asked for the number of moles of nitrogen gas. The question
assumes ideal gases and Avogadro's theory states that two gases at the same temperature, pressure, and
volume would contain the same number of molecules. If you have the same number of molecules, you have
the same number of moles; however, the masses will be different.
PTS: 1
REF: C
32. ANS:
V1 = 775 mL
V2 = 825 mL
T1 = –28ºC + 273 = 245 K
T2 = 15 K + 273 K = 288 K
P1 = 92.5 kPa
P2 = ?
OBJ: 9.4
STA: GA2.04
The pressure at the base of Mt. Logan is 101 kPa.
PTS: 1
33. ANS:
REF: I
OBJ: 9.2
STA: GA2.04
P1
V1
T1
P2
V2
T2
275 kPa
2.5 L
35ºC + 273 = 308 K
100 kPa
5.0 L
?
10
The new temperature will be –49ºC.
PTS: 1
34. ANS:
REF: I
OBJ: 9.2
STA: GA2.04
P1
V1
T1
P2
V2
T2
101.325 kPa
10.0 L
273 K
100 kPa
?
298 K
The difference in size would be 11.1 L – 10.0 L = 1.1 L.
The balloon will not burst since there is room for a 12% increase in its volume.
PTS: 1
REF: I
35. ANS:
mass of full extinguisher = 3500 g
mass of empty extinguisher = 2735 g
V = 4.25 L
T = 25ºC + 273 = 298 K
R = 8.31 kPa L/mol K
P=?
n=?
mass of CO2 = 3500 g – 2735 g = 765 g
OBJ: 9.2
STA: GA2.04
11
The pressure reading was 1.01  104 kPa.
PTS: 1
36. ANS:
REF: I
OBJ: 9.4
STA: GA2.04
P
V
n
R
T
92.7 kPa
?
4.25 mol
8.31 kPa L/mol K
30 oC + 273 = 303 K
The volume of the balloon will be 115 L.
PTS: 1
37. ANS:
REF: I
OBJ: 9.4
STA: GA2.04
According to the law of combining volumes, 100 L of O2 are required.
PTS: 1
REF: I
OBJ: 10.2
38. ANS:
16KNO3 (s) + 24C(s) + S8 (s)  8N2 (g) + 24CO2 (g) + 8K2S(s)
STA: GA2.04
12
The total volume of all the gases produced in the explosion is 63.7 L.
PTS: 1
REF: I
OBJ: 10.4
STA: GA2.05