Chapter 5: Gases
1. Gases generally have
A)
low density
B)
high density
C)
closely packed particles
D)
no increase in volume when temperature is increased
E)
no decrease in volume when pressure is increased
2. Pressure is
A)
defined as the mass that an object exerts when at rest
B)
measured in Newtons
C)
defined as the number of moles of substance divided by the mass of the substance
D)
defined as the force per unit area
E)
measured in grams
3. The SI unit of pressure is the
A)
ampere
B)
kilojoule
C)
newton
D)
gram
E)
pascal
4. Which of the following would represent the greatest pressure?
A)
0.680 atm
B)
517 mmHg
C)
11.4 psi
D)
62106 Pa
E)
14.1 in Hg
5. A glass column is filled with mercury and inverted in a pool of mercury. The mercury
column stabilizes at a height of 729 mm above the pool of mercury. What is the pressure of
the atmosphere?
A)
1.04 atm
B)
0.729 atm
C)
0.959 atm
D)
456 atm
E)
0.639 atm
6. The local weather forecaster reports that the current barometric pressure is 30.4 inches of
mercury. What is the current pressure in atmospheres?
A)
1.02 atm
B)
10.29 atm
C)
1.00 atm
D)
4.05 atm
E)
910 atm
7. A physics experiment is conducted at a pressure of 14.4 kPa. What is this pressure in
mmHg?
A)
18.9 mmHg
B)
1.92 mmHg
C)
mmHg
D)
108 mmHg
E)
mmHg
8. The air pressure in the inner tube of a tire on a typical racing bike is held at a pressure of
about 112 psi. Convert this pressure to atm.
A)
0.147 atm
B)
7.62 atm
C)
0.112 atm
D)
0.131 atm
E)
112 atm
9. Boyle’s law states that:
A)
Equal amounts of gases occupy the same volume at constant temperature and
pressure.
B)
The volume of a fixed amount of gas is inversely proportional to its pressure at
constant temperature.
C)
The volume of a fixed amount of gas is directly proportional to its temperature in
Kelvin at constant pressure.
D)
The total pressure of a mixture of gases is the simple sum of the partial pressure of
all of the gaseous compounds.
E)
The rates of effusion of gases are inversely proportional to the square roots of their
molar masses.
1.44 104
1.89 10−2
10. Avogadro’s law states that:
A)
Equal amounts of gases occupy the same volume at constant temperature and
pressure.
B)
The volume of a fixed amount of gas is inversely proportional to its pressure at
constant temperature.
C)
The volume of a fixed amount of gas is directly proportional to its temperature in
Kelvin at constant pressure.
D)
The total pressure of a mixture of gases is the simple sum of the partial pressure of
all of the gaseous compounds.
E)
The rates of effusion of gases are inversely proportional to the square roots of their
molar masses.
11. Charles’s law states that:
A)
Equal amounts of gases occupy the same volume at constant temperature and
pressure.
B)
The volume of a fixed amount of gas is inversely proportional to its pressure at
constant temperature.
C)
The volume of a fixed amount of gas is directly proportional to its temperature in
Kelvin at constant pressure.
D)
The total pressure of a mixture of gases is the simple sum of the partial pressure of
all of the gaseous compounds.
E)
The rates of effusion of gases are inversely proportional to the square roots of their
molar masses.
12. Consider a sample of helium gas in a container fitted with a piston, as pictured below. The
piston is frictionless, but has a mass of 10.0 kg. How many of the following processes will
cause the piston to move away from the base and decrease the pressure of the gas? Assume
ideal behavior.
10.0 kg
base
heating the helium
removing some of the helium from the container
turning the container on its side
decreasing the pressure outside the container
A)
0
B)
1
C)
2
D)
3
E)
4
13. A gas sample is held at constant pressure. The gas occupies 3.62 L of volume when the
temperature is 21.6°C. Determine the temperature at which the volume of the gas is 3.42 L.
A)
312 K
B)
278 K
C)
20.4 K
D)
295 K
E)
552 K
14. You have 41.6 g of O2 gas in a container with twice the volume as one with CO2 gas. The
pressure and temperature of both containers are the same. Calculate the mass of carbon
dioxide gas you have in the container.
A)
57.2 g
B)
0.650 g
C)
28.6 g
D)
2.60 g
E)
none of these
15. Gaseous chlorine is held in two separate containers at identical temperature and pressure.
The volume of container 1 is 1.30 L, and it contains 6.70 mol of the gas. The volume of
container 2 is 2.33 L. How many moles of the gas are in container 2?
A)
12.0 mol
B)
20.3 mol
C)
0.452 mol
D)
3.74 mol
E)
none of these
16. A balloon has a volume of 2.32 liters at 24.0°C. The balloon is heated to 48.0°C. Calculate
the new volume of the balloon.
A)
2.32 L
B)
2.51 L
C)
2.15 L
D)
4.64 L
E)
1.16 L
17. Consider a sample of gas in a container on a comfortable spring day. The Celsius
temperature suddenly doubles, and you transfer the gas to a container with twice the volume
of the first container. If the original pressure was 12 atm, what is a good estimate for the
new pressure?
A)
3 atm
B)
5.5 atm
C)
6.4 atm
D)
12 atm
E)
15 atm
18. Body temperature is about 309 K. On a cold day, what volume of air at 276 K must a person
with a lung capacity of 2.2 L breathe in to fill the lungs?
A)
2.46 L
B)
1.97 L
C)
2.08 L
D)
3.93 L
E)
none of these
19. You have a certain mass of helium gas (He) in a rigid steel container. You add the same
mass of neon gas (Ne) to this container. Which of the following best describes what
happens? Assume the temperature is constant.
A)
The pressure in the container doubles.
B)
The pressure in the container increases but does not double.
C)
The pressure in the container more than doubles.
D)
The volume of the container doubles.
E)
The volume of the container more than doubles.
20. You are holding two balloons, an orange balloon and a blue balloon. The orange balloon is
filled with neon (Ne) gas and the blue balloon is filled with argon (Ar) gas. The orange
balloon has twice the volume of the blue balloon. Which of the following best represents the
mass ratio of Ne:Ar in the balloons?
A)
1:1
B)
1:2
C)
2:1
D)
1:3
E)
3:1
21. You are holding four identical balloons each containing 10.0 g of a different gas. The
balloon containing which gas is the largest balloon?
A)
H2
B)
He
C)
Ne
D)
O2
E)
All have the same volume.
22. Which contains the largest number of molecules?
A)
Flask A
B)
Flask B
C)
Flask C
D)
All are the same.
E)
More information is need to answer this.
23. In which flask are the molecules least polar and therefore most ideal in behavior?
A)
Flask A
B)
Flask B
C)
Flask C
D)
All are the same.
E)
More information is needed to answer this.
24. In which flask do the molecules have the highest average velocity?
A)
Flask A
B)
Flask B
C)
Flask C
D)
All are the same.
E)
More information is needed to answer this.
25. The ratio of the number of moles of gas in the first container compared to that in the second
is
A)
1:1
B)
4:1
C)
1:4
D)
2:1
E)
1:2
26. The ratio of the average velocity of particles in the first container compared to that in the
second is
A)
1:1
B)
4:1
C)
1:4
D)
2:1
E)
1:2
27. In which flask is there 0.039 mol of gas?
A)
Flask A
B)
Flask B
C)
Flask C
D)
all
E)
none
28. In which single flask do the molecules have the greatest mass, the greatest average velocity,
and the highest kinetic energy?
A)
Flask A
B)
Flask B
C)
Flask C
D)
All are the same.
E)
No one flask has all these.
29. A gas sample is heated from -20.0°C to 57.0°C and the volume is increased from 2.00 L to
4.50 L. If the initial pressure is 0.140 atm, what is the final pressure?
A)
0.0477 atm
B)
–0.177 atm
C)
0.411 atm
D)
0.242 atm
E)
0.0811 atm
30. A sample of oxygen gas has a volume of 1.72 L at 27°C and 800.0 torr. How many oxygen
molecules does it contain?
A)
B)
C)
D)
E)
none of these
31. You fill a balloon with 2.50 moles of gas at 22°C at a pressure of 1.62 atm. What is the
volume of the balloon?
A)
15.7 L
B)
98.0 L
C)
37.4 L
D)
2.79 L
E)
22.4 L
4.43 1022
3.36 1025
4.92 1023
8.19 1024
32. A sample of helium gas occupies 14.7 L at 23°C and 0.956 atm. What volume will it occupy
at 40°C and 1.20 atm?
A)
19.5 L
B)
20.4 L
C)
11.1 L
D)
12.4 L
E)
14.9 L
33. A 3.60-L sample of carbon monoxide is collected at 55°C and 0.869 atm. What volume will
the gas occupy at 1.05 atm and 25°C?
A)
1.35 L
B)
3.95 L
C)
2.71 L
D)
3.28 L
E)
none of these
34. Mercury vapor contains Hg atoms. What is the volume of 201 g of mercury vapor at 822 K
and 0.512 atm?
A)
132 L
B)
L
C)
175 L
D)
34.5 L
E)
17.3 L
35. What volume is occupied by 21.0 g of methane (CH4) at 27°C and 1.25 atm?
A)
37.2 L
B)
25.8 L
C)
2.32 L
D)
L
E)
not enough data to calculate
2.65 104
4.14 102
36. An automobile tire is filled with air at a pressure of 27.0 lb/in2 at 25°C. A cold front moves
through and the temperature drops to 5°C. Assuming no change in volume, what is the new
tire pressure?
A)
5.40 lb/in2
B)
25.2 lb/in2
C)
28.9 lb/in2
D)
135 lb/in2
E)
4.63 lb/in2
37. Which conditions of P, T, and n, respectively, are most ideal?
A)
high P, high T, high n
B)
low P, low T, low n
C)
high P, low T, high n
D)
low P, high T, high n
E)
low P, high T, low n
38. A 7.94-g piece of solid CO2 (dry ice) is allowed to sublime in a balloon. The final volume of
the balloon is 1.00 L at 301 K. What is the pressure of the gas?
A)
4.46 atm
B)
atm
C)
3.11 atm
D)
0.224 atm
E)
none of these
39. A sample of 35.1 g of methane gas has a volume of 3.11 L at a pressure of 2.70 atm.
Calculate the temperature.
A)
2.92 K
B)
46.8 K
C)
320 K
D)
32.4 K
E)
35.0 K
40. A 41.1-g sample of Ne gas exerts a certain pressure in a container of fixed volume. What
mass of Ar is required to exert half the pressure at the same conditions of volume and
temperature?
1.96 102
A)
81.4 g Ar
B)
1.02 g Ar
C)
163 g Ar
D)
821 g Ar
E)
40.7 g Ar
41. A sample of gas is in a 50.0-mL container at a pressure of 645 torr and a temperature of
25°C. The entire sample is heated to a temperature of 35°C and transferred to a new
container whose volume is 98.7 mL. The pressure of the gas in the second container is
about:
A)
457 torr
B)
316 torr
C)
torr
D)
65 torr
E)
338 torr
42. Given a cylinder of fixed volume filled with 1 mol of argon gas, which of the following is
correct? (Assume all gases obey the ideal gas law.)
A)
If the temperature of the cylinder is changed from 25°C to 50°C, the pressure
inside the cylinder will double.
B)
If a second mole of argon is added to the cylinder, the ratio T/P would remain
constant.
C)
A cylinder of identical volume filled with the same pressure of helium must
contain more atoms of gas because He has a smaller atomic radius than argon.
D)
Two of the above.
E)
None of the above.
43. For an ideal gas, which pairs of variables are inversely proportional to each other (if all
other factors remain constant)?
1. V and T
2. T and n
3. n and V
4. P and T
A)
1 and 2 only
B)
3 and 4 only
C)
2 only
D)
1 and 3 only
1.32 103
E)
1, 3, and 4 only
44. For a gas, which two variables are directly proportional to each other (if all other conditions
remain constant)?
1. T and n
2. V and n
3. V and T
A)
1 only
B)
2 only
C)
3 only
D)
1 and 2 only
E)
2 and 3 only
45. The temperature of a specific amount of gas in a sealed container changes from 20.0°C to
40.0°C. If the volume remains constant, the pressure will change from 755 mmHg to
A)
1510 mmHg
B)
707 mmHg
C)
378 mmHg
D)
807 mmHg
E)
755 mmHg
46. Which gas has the highest density?
A)
He
B)
Cl2
C)
CH4
D)
NH3
E)
all gases the same
47. For which gas do the molecules have the highest average velocity?
A)
He
B)
Cl2
C)
CH4
D)
NH3
E)
all gases the same
48. Which gas sample has the greatest number of molecules?
A)
He
B)
Cl2
C)
CH4
D)
NH3
E)
all gases the same
49. For which gas are the molecules diatomic?
A)
He
B)
Cl2
C)
CH4
D)
NH3
E)
all gases the same
50. For which gas are the collisions elastic?
A)
He
B)
Cl2
C)
CH4
D)
NH3
E)
all gases the same
51. For which gas do the molecules have the smallest average kinetic energy?
A)
He
B)
Cl2
C)
CH4
D)
NH3
E)
all gases the same
A plastic bag is weighed and then filled successively with two gases, X and Y. The following
data are gathered:
Temperature: 0.0°C (273 K)
Pressure: 1.00 atmosphere
Mass of empty bag: 20.77 g
Mass of bag filled with gas X: 24.97 g
Mass of 1.12 liters of air at conditions given: 1.30 g
Volume of bag: 1.12 liter
Molar volume at STP: 22.4 liters
52. The mass of 1.12 liters of gas Y is found to be 6.23 g. The density of gas Y is
A)
10.6 g/L
B)
5.56 g/L
C)
15.6 g/L
D)
0.200 g/L
E)
0.180 g/L
53. The molar mass of gas Y is
A)
56.0 g/mol
B)
89.0 g/mol
C)
125 g/mol
D)
140. g/mol
E)
157 g/mol
54. The bag is emptied and refilled, successively, with gases X and Y, this time at 1 atm pressure
and a temperature 30°C higher. Assume that the volume of the bag is the same as before.
Which one of the following statements is wrong?
A)
The full bag contains fewer molecules of each gas than it did at 0.0°C.
B)
The ratio of the density of gas Y to the density of gas X is the same as at 0.0°C.
C)
The molar masses of the two gases are the same as they were at 0.0°C.
D)
The mass of each gas filling the bag is now 303/273 times the mass held at 0.0°C.
E)
The average velocity of the molecules of gas X at 30°C is higher than it was at
0.0°C.
55. Argon has a density of 1.78 g/L at STP. How many of the following gases have a density at
STP greater than that of argon?
Cl2
He
NH3
NO2
A)
0
B)
1
C)
2
D)
3
E)
4
56. Which of the following is the best qualitative graph of P versus molar mass of a 1-g sample
of different gases at constant volume and temperature?
A)
B)
C)
D)
E)
none of these
57. It is found that 250. mL of a gas at STP has a mass of 0.700 g. What is the molar mass?
A)
62.7 g/mol
B)
2.80 g/mol
C)
15.9 g/mol
D)
11.2 g/mol
E)
128 g/mol
58. Given reaction 2NH3(g) + 3Cl2(g) → N2(g) + 6HCl(g), you react 5.0 L of NH3 with 5.0 L of
Cl2 measured at the same conditions in a closed container. Calculate the ratio of pressures in
the container (Pfinal/Pinitial).
A)
0.75
B)
1.00
C)
1.33
D)
1.50
E)
none of these
59. Given reaction N2 + 3H2 → 2NH3, you mix 1 mol each of nitrogen and hydrogen gases
under the same conditions in a container fitted with a piston. Calculate the ratio of volumes
of the container (Vfinal/Vinitial).
A)
0.67
B)
1.00
C)
1.33
D)
1.50
E)
none of these
60. You carry out the reaction represented by the following balanced equation:
N2(g) + 3H2(g) → 2NH3(g)
You add an equal number of moles of nitrogen and hydrogen gases in a balloon. The
volume of the balloon is 1.00 L before any reaction occurs. Determine the volume of the
balloon after the reaction is complete. Assume constant temperature.
A)
0.330 L
B)
0.670 L
C)
1.00 L
D)
1.50 L
E)
3.00 L
61. When 0.72 g of a liquid is vaporized at 110°C and 0.967 atm, the gas occupies a volume of
0.559 L. The empirical formula of the gas is CH2. What is the molecular formula of the gas?
A)
CH2
B)
C2H4
C)
C3H6
D)
C4H8
E)
none of these
62. Gaseous reacts with according to the following equation:
What volume of oxygen gas at STP is needed to react with 5.75 mol of ?
A)
17.3 L
L
3.86 102
D)
L
E)
Not enough information is given to solve the problem.
63. A 3.54 gram sample of a certain diatomic gas occupies a volume of 3.30-L at 1.00 atm and a
temperature of 45°C. Identify this gas.
A)
B)
C)
D)
E)
64. Air has an average molar mass of 29.0 g/mol. The density of air at 0.97 atm and 30.0°C is:
A)
29.0 g/L
B)
39.0 g/mL
C)
1.13 g/L
D)
1.35 g/mL
E)
11.4 g/L
65. Calculate the density of nitrogen at STP.
A)
0.312 g/L
B)
0.625 g/L
C)
0.800 g/L
D)
1.25 g/L
E)
1.60 g/L
66. If a 17.90-g sample of a gas occupies 10.0 L at STP, what is the molar mass of the gas at
125°C?
A)
5.48 g/mol
B)
40.1 g/mol
C)
18.4 g/mol
D)
58.5 g/mol
E)
Not enough information is given.
1.29 102
67. A 3.31-g sample of lead nitrate, , molar mass = 331 g/mol, is heated in an
evacuated cylinder with a volume of 2.37 L. The salt decomposes when heated, according to
the equation:
Assuming complete decomposition, what is the pressure in the cylinder after decomposition
and cooling to a temperature of 300. K? Assume the takes up negligible volume.
A)
0.260 atm
B)
0.208 atm
C)
0.0519 atm
D)
0.364 atm
E)
34.4 atm
68. The purity of a sample containing zinc and weighing 0.312 g is determined by measuring
the amount of hydrogen formed when the sample reacts with an excess of hydrochloric acid.
The determination shows the sample to be 84.0% zinc. What amount of hydrogen (measured
at STP) was obtained?
A)
L
B)
g
C)
mole
D)
molecules
E)
atoms
69. What volume of carbon dioxide measured at STP will be formed by the reaction of 1.47 mol
of oxygen with 0.900 mol of ethyl alcohol, CH3CH2OH?
A)
40.3 mL
B)
22.0 L
C)
32.9 L
D)
49.4 L
E)
0.980 L
70. What volume of measured at STP is produced by the combustion of 6.27 g of
natural gas according to the following equation?
2.62 10−1
1.30 10−1
4.77 10−3
2.41 1021
2.41 1021