Ch 5 – Practice Problems
1.
A glass column is filled with mercury and inverted in a pool of mercury. The mercury column stabilizes at a height of 735 mm
above the pool of mercury. What is the pressure of the atmosphere?
A) 0.697 atm
B) 0.735 atm
C) 0.967 atm
D) 1.03 atm
E)
194 atm
2.
The volume of a balloon is 3.78 L at 22.8°C. The balloon is heated to 42.4°C. Calculate the new volume of the balloon.
A) 7.03 L
B) 4.03 L
C) 2.03 L
D) 3.55 L
E)
3.78 L
Use the following to answer question 3:
Consider three 1-L flasks at the same temperature and pressure. Flask A contains CO gas, flask B contains N 2 gas, and flask C
contains O2 gas.
3.
Which contains the lowest density?
A) flask A
B) flask B
C) flask C
D) All are the same.
E)
Two of the flasks contain gases at the same density.
4.
A cylinder of oxygen gas contains 26.4 g of O 2. Another cylinder, twice the volume of the cylinder containing oxygen (and at
the same conditions of pressure and temperature), contains CO 2 gas. Assuming ideal behavior, what is the mass of the carbon
dioxide?
A) 72.6 g
B) 52.8 g
C) 13.2 g
D) 36.3 g
E)
none of these
Use the following to answer question 5:
Samples of the gases H2(g) and SO2(g) have equal masses and are at the same temperature and pressure. Calculate the following:
V
5.
The ratio of volumes
A)
B)
C)
D)
1.0
0.18
32
5.6
E)
180
6.
V
H2
SO 2
A balloon contains 10.0 g of neon gas. With the temperature kept constant, 10.0 g of argon gas is added. What
happens?
A)
B)
C)
D)
E)
The balloon doubles in volume.
The volume of the balloon expands by more than 2 times.
The volume of the balloon expands by less than 2 times.
The balloon stays the same size, but the pressure increases.
none of these
7.
The volume of a helium balloon is 1.85 L at 24.0°C and 1.00 atm at sea level. The balloon is released and floats upward. At a
certain altitude, the balloon has a volume of 2.14 L and the temperature is 15.2°C. What is the atmospheric pressure at this
altitude?
A) 0.538 atm
B) 0.839 atm
C) 0.891 atm
D) 1.36 atm
E)
none of these
Use the following to answer question 8:
Three 1.00-L flasks at 25°C and 725 torr contain the gases CH4 (flask A), CO2 (flask B), and C2H6 (flask C).
8.
In which flask is there 0.039 mol of gas?
A) flask A
B) flask B
C) flask C
D) all
E)
none
9.
Body temperature is about 308 K. On a cold day, what volume of air at 273 K must a person with a lung capacity of 2.00 L
breathe in to fill the lungs?
A) 2.26 L
B) 1.77 L
C) 1.13 L
D) 3.54 L
E)
none of these
Use the following to answer question 10:
Consider two samples of helium in separate containers of the same volume. Sample 1 has an absolute temperature four times that of
Sample 2. Both samples are at the same pressure.
10.
Calculate the ratio n1/n2.
A) 1:1
B) 4:1
C) 1:4
D) 2:1
E)
1:2
11.
A cylinder is fitted with a movable piston. The pressure inside the cylinder is Pi and the volume is Vi. What is the new pressure
in the system when the piston decreases the volume of the cylinder by half?
A) (1/4)Pi
B) (1/2)Pi
C) 2Pi
D) 2ViPi
E)
Pi2
12.
A 8.80-g piece of solid CO2 (dry ice) is allowed to sublime in a balloon. The final volume of the balloon is 1.30 L at 310. K.
What is the pressure of the gas?
A) 3.91 atm
B) 0.256 atm
C) 6.88  10-5 atm
D) 1.72  102 atm
E)
47.7 atm
13.
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 will 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 these are correct.
E)
None of these is correct.
14.
Which of the following relationships is not true?
A) PV = constant when temperature and moles of gas are held constant.
B) V/T = constant when pressure and moles of gas are held constant.
C) nT = constant when pressure and volume are held constant.
D) P/n = constant when volume and temperature are held constant.
E)
All of these are true.
15.
A sample of oxygen gas has a volume of 4.50 L at 27°C and 800.0 torr. How many oxygen molecules does it contain?
A) 1.16  1023
B) 5.8  1022
C) 2.32  1024
D) 1.16  1022
E)
none of these
16.
Mercury vapor contains Hg atoms. What is the volume of 200. g of mercury vapor at a temperature of 822 K and 0.500 atm?
A) 135 L
B) 82.2 L
C) 329 L
D) 67.2 L
E)
none of these
17.
A sample of nitrogen gas has a volume of 150.0 mL at STP. What volume does the gas occupy if the absolute temperature and
pressure are each tripled?
A) 450.0 mL
B) 50.00 mL
C) 150.0 mL
D) 500.0 mL
E)
67.20 L
18.
Consider a sample of neon gas in a container fitted with a movable piston (assume the piston is massless and frictionless). The
temperature of the gas is increased from 20.0°C to 40.0°C. The density of neon
A) increases less than 10%.
B) decreases less than 10%.
C) increases more than 10%.
D) decreases more than 10%.
E)
does not change.
19.
The valve between a 3.25-L tank containing O2(g) at 8.64 atm and a 2.48-L tank containing Ne(g) at 5.40 atm is opened.
Calculate the ratio of partial pressures (O2:Ne) in the container.
A) 1.31
B) 1.60
C) 2.10
D) 0.477
E)
0.615
20.
Air is 79% N2 and 21% O2 by volume. Calculate the density of air at 1.0 atm, 25°C.
A) 0.590 g/L
B) 1.18 g/L
C) 2.46 g/L
D) 14.1 g/L
E)
none of these
21.
Air is 79% N2 and 21% O2 by volume. Calculate the mass of oxygen in a 2.0-L bottle of air at 1.0 atm, 25°C.
A) 0.550 g
B) 1.81 g
C) 2.36 g
D) 2.62 g
E)
none of these
22.
At STP the mass of 860.0 mL of a certain gas is 1.075 g. What is a possible identity of this gas?
A) H2
B) N2
C) O2
D) CO2
E)
Ne
Use the following to answer questions 23-24:
Four identical 1.0-L flasks contain the gases He, Cl2, CH4, and NH3, each at 0°C and 1 atm pressure.
23.
Which gas sample has the greatest number of molecules?
A) He
B) Cl2
C) CH4
D) NH3
E)
All the gases have the same number of molecules.
24.
Which gas has the highest density?
A) He
B) Cl2
C) CH4
D) NH3
E)
All the gases have the same density.
Use the following to answer questions 25-26:
A plastic bag is weighed and then filled successively with two gases, X and Y. The following data are gathered:
Temperature: 0.0°C
Pressure: 1.00 atm
Mass of empty bag: 20.77 g
Mass of bag filled with gas X: 24.97 g
Mass of 1.12 L of air at conditions given: 1.30 g
Volume of bag: 1.12 L
Molar volume at STP: 22.4 L
25.
The mass of 1.12 L 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.
26.
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.
27.
It is found that 250. mL of gas at STP has a mass of 1.00 g. What is the molar mass?
A) 89.6 g/mol
B) 28.0 g/mol
C) 14.0 g/mol
D) 22.4 g/mol
E)
none of these
28.
Air has an average molar mass of 29.0 g/mol. The density of air at 1.00 atm and 30°C is
A) 29.0 g/L.
B) 40.0 g/mL.
C) 1.17 g/L.
D) 1.29 g/L.
E)
12 g/L.
29.
Equimolar amounts of the gases N2 and H2 are mixed in a closed container fitted with a piston (allowing the volume of the
container to change, thus keeping the pressure constant). Calculate the ratio of the final volume of the container to the initial
volume of the container when the reaction N2 + 3H2  2NH3 goes to completion.
A) 2/3
B) 3/2
C) 1
D) 1/3
E)
none of these
30.
The density of a certain diatomic gas is 1.696 g/L at STP. Identify the gas.
A) H2
B) N2
C) O2
D) F2
E)
Cl2
31.
Potassium chlorate decomposes upon heating as follows:
2KClO3(s)  2KCl(s) + 3O2(g)
A 2.36-g sample of KClO3 decomposes, and the oxygen at 23.8°C and 0.930 atm is collected. What volume of oxygen gas will
be collected, assuming 100% yield?
A)
B)
C)
D)
E)
0.504 mL
1.93 mL
0.756 mL
0.0607 mL
0.0404 mL
32.
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
33.
A volatile liquid produced 0.387 g of vapor in a 258.0-mL flask at 100.0°C and 0.995 atm. What is the molar mass of the
liquid?
A) 8.39 g/mol
B) 36.6 g/mol
C) 46.1 g/mol
D) 12.3 g/mol
E)
31.3 g/mol
34.
What volume of carbon dioxide measured at STP will be formed by the reaction of 1.30 mol of oxygen with 9.00  10–1 mol of
ethyl alcohol (CH3CH2OH)?
A) 8.70 L
B) 19.4 L
C) 28.0 L
D) 40.3 L
E)
91.9 L
35.
If a 2.15-g sample of a gas occupies 750. mL at STP, what is the molar mass of the gas at 125°C?
A) 3.07  10–2
B) 64.2
C) 70.1
D) 75.0
E)
Not enough information is given.
36.
Into a 3.50-liter container at 23°C are placed 1.18 mol of O2 gas and 4.70 mol of solid C (graphite). If the carbon and oxygen
react completely to form CO(g), what will be the final pressure in the container at 23°C?
A) 16.4 atm
B) 32.6 atm
C) 0.636 atm
D) 40.8 atm
E)
8.19 atm
37.
When a mixture is prepared from 15.0 L of ammonia and 15.0 L of chlorine measured at the same conditions, these compounds
react according to the following equation:
2NH3(g) + 3Cl2(g)  N2(g) + 6HCl(g)
When the reaction is completed, what are the volumes of the gases (NH 3, Cl2, N2, and HCl, respectively)? Assume the final
volumes are measured under identical conditions.
A)
B)
C)
D)
E)
38.
0.00 L, 5.00 L, 7.50 L, and 45.0 L
5.00 L, 0.00 L, 5.00 L, and 30.0 L
0.00 L, 0.00 L, 7.50 L, and 45.0 L
0.00 L, 0.00 L, 5.00 L, and 30.0 L
0.00 L, 10.0 L, 15.0 L, and 90.0 L
A mixture of KCl and KClO3 weighing 1.80 g was heated; the dry O2 generated occupied 1.40  102 mL at STP. What percent
of the original mixture was KClO3? KClO3 decomposes as follows:
2KClO3(s)  2KCl(s) + 3O2(g)
A)
B)
C)
D)
E)
28.4%
37.2%
42.6%
63.8%
72.6%
39.
An excess of sodium hydroxide is treated with 1.5 L of dry hydrogen chloride gas measured at STP. What is the mass of sodium
chloride formed?
A) 8.7  102 g
B) 1.5  103 g
C) 1.1  103 g
D) 3.9 g
E)
1.8  103 g
40.
Magnesium metal reacts with hydrochloric acid to form aqueous magnesium chloride and hydrogen gas. An excess of
magnesium is reacted with 20.0 mL of 3.00 M hydrochloric acid, and all of the hydrogen is collected in a balloon at 25°C and
1.00 atm. What is the expected volume of the balloon?
A) 0.672 L
B) 0.734 L
C) 1.34 L
D) 1.47 L
E)
22.4 L
41.
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
42.
A 3.50-g sample of lead(II) nitrate, Pb(NO3)2, molar mass = 331 g/mol, is heated in an evacuated cylinder with a volume of 1.75
L. The salt decomposes when heated, according to the equation
2Pb(NO3)2(s)  2PbO(s) + 4NO2(g) + O2(g)
Assuming complete decomposition, what is the pressure in the cylinder after decomposition and cooling to a temperature of 270.
K? Assume the PbO(s) takes up negligible volume.
A)
B)
C)
D)
E)
0.335 atm
0.134 atm
0.669 atm
0.469 atm
0.673 atm
43.
The purity of a sample containing zinc and weighing 0.198 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) 0.152 L
B) 0.0330 g
C) 3.42  10–3 mol
D) 1.53  1021 molecules
E)
1.53  1021 atoms
44.
At 1000°C and 10. torr, the density of a certain element in the gaseous state is 2.9  10-3 g/L. The element is
A) Ne.
B) He.
C) Na.
D) Ar.
E)
Hg.
45.
A 1.00-g sample of a gaseous compound of boron and hydrogen occupies 0.820 L at 1.00 atm and 3C. What is the molecular
formula for the compound?
A) BH3
B) B2H6
C) B4H10
D) B3H12
E)
B5H14
46.
How many of the following gases at STP are less dense than air at STP?
NH3, He, Kr, and F2
A)
B)
C)
D)
E)
47.
0
1
2
3
4
The oxidation of nitric oxide to nitrogen dioxide is
2NO(g) + O2(g)  2NO2(g)
If 100.0 mL of NO (at STP) reacts with 400.0 mL of O 2 at STP, calculate the partial pressure of NO2 in the final reaction
mixture.
A)
B)
C)
D)
E)
48.
0.222 atm
0.333 atm
0.286 atm
0.250 atm
1.00 atm
A balloon contains an anesthetic mixture of cyclopropane (C3H6) and oxygen (O2) at
170 torr and 550 torr, respectively. What is the ratio of the number of moles of cyclopropane to the number of moles of oxygen?
ncp/nO2 = ?
A)
B)
C)
D)
E)
0.24
0.76
0.31
3.2
0.27
49.
A 250.0-L cylinder contains 65.0% He(g) and 35.0% Kr(g) by mass at 25.0° C and 1.35 atm total pressure. What is the partial
pressure of He in this container?
A) 0.473 atm
B) 0.675 atm
C) 0.878 atm
D) 1.32 atm
E)
1.35 atm
50.
A 0.234-g sample of a gas in a 275-mL container at 23.5°C exerts a pressure of 0.292 atm What is the molar mass of the gas?
A) 5.62 g/mol
B) 70.9 g/mol
C) 0.0141 g/mol
D) 32.0 g/mol
E)
none of these
51.
A 130.-mL sample of gas is collected over water at 22°C and 753 torr. What is the volume of the dry gas at STP? (The vapor
pressure of water at 22°C is 20. torr.)
A) 135 mL
B) 119 mL
C) 130. mL
D) 111 mL
E)
none of these
52.
A vessel with a volume of 10.2 L contains 3.14 g of nitrogen gas, 0.596 g of hydrogen gas, and 81.6 g of argon gas. At 26.0°C,
what is the pressure in the vessel?
A) 0.513 atm
B) 2.93 atm
C) 205 atm
D) 5.89 atm
E)
9.11  104 atm
53.
A 275.0-mL sample of O2 is collected over water at 60.0°C. The total pressure is 755 torr. What is the volume of the O 2 at the
STP? (The vapor pressure of water at 60°C is 149 torr).
A) 180.0 mL
B) 224.0 mL
C) 244.0 mL
D) 333.0 mL
E)
none of these
54.
Oxygen gas, generated by the reaction 2KClO3(s)  2KCl(s) + 3O2(g), is collected over water at 27°C in a 3.76-L vessel at a
total pressure of 750. torr. (The vapor pressure of H 2O at 27°C is 26.0 torr.) How many moles of KClO 3 were consumed in the
reaction?
A) 0.104 mol
B) 1.08 mol
C) 0.0970 mol
D) 73.7 mol
E)
0.218 mol
55.
A gaseous mixture containing 1.5 mol Ar and 3.5 mol CO 2 has a total pressure of 7.0 atm. What is the partial pressure of CO 2?
A) 1.8 atm
B) 2.1 atm
C) 3.5 atm
D) 4.9 atm
E)
2.4 atm
56.
A 240.0-L cylinder contains 67.0% He(g) and 33.0% Kr(g) by mass at 24.0°C and 1.35 atm total pressure. What is the mass of
He in this container?
A) 25.6 g
B) 643 g
C) 77.6 g
D) 52.0 g
E)
35.7 g
Use the following to answer question 57:
Three 1.00-L flasks at 25°C and 725 torr contain the gases CH4 (flask A), CO2 (flask B), and C2H6 (flask C).
57.
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
E)
none
Use the following to answer question 58:
Consider three 1.0-L flasks at STP. Flask A contains N2 gas, flask B contains Kr gas, and flask C contains He gas.
58.
In which flask do the gas particles have the lowest average kinetic energy?
A) flask A
B) flask B
C) flask C
D) The pas particles in all of the flasks have the same average kinetic energy.
E)
The gas particles in two of the flasks have the same average kinetic energy.
Use the following to answer questions 59-61:
Four identical 1.0-L flasks contain the gases He, Cl2, CH4, and NH3, each at 0°C and 1 atm pressure.
59.
For which gas do the molecules have the highest average velocity?
A) He
B) Cl2
C) CH4
D) NH3
E)
The molecules of all the gases have the same average velocity.
60.
For which gas are the collisions elastic?
A) He
B) Cl2
C) CH4
D) NH3
E)
The collisions are elastic for all the gases.
61.
For which gas do the molecules have the smallest average kinetic energy?
A) He
B) Cl2
C) CH4
D) NH3
E)
The molecules of all the gases have the same average kinetic energy.
Use the following to answer question 62:
Consider three 1-L flasks at the same temperature and pressure. Flask A contains CO gas, flask B contains N 2 gas, and flask C
contains O2 gas.
62.
In which flask do the molecules have the greatest momentum per impact?
A) flask A
B) flask B
C) flask C
D) The molecules in all the flasks have the same momentum per impact.
E)
The molecules in two of the flasks have the same momentum per impact.
63.
Under which of the following conditions does a gas behave most ideally?
A) STP
B) P = 1.0 atm, T = 100.0°C
C) P = 0.50 atm, T = 100.0°C
D) P = 0.50 atm, T = 0.0°C
E)
P = 2.0 atm, T = -100.0°C
Use the following to answer question 64:
Calculate the following ratios for a gas at Kelvin temperatures T1 and T2 where T2 = 2T1.
64.
Average kinetic energy at T1 : Average kinetic energy at T2
A) 0.50
B) 2.0
C) 1.0
D) 1.4
E)
0.71
65.
The kinetic-molecular theory of gases does not assume that
A) gases are made up of tiny particles in constant chaotic motion.
B) gas particles are very small compared to the average distance between the particles.
C) gas particles collide with the walls of their container in elastic collisions.
D) the average velocity of gas particles is directly proportional to the absolute temperature.
E)
All of these are correct.
66.
Which statement about kinetic energy (K.E.) is true?
A) All objects moving with the same velocity have the same K.E.
B) As the velocity of a body increases, its K.E. decreases.
C) The K.E. of a body will double if its velocity doubles.
D) The K.E. of a body is independent of its mass.
E)
None of these statements is true.
67.
Consider separate samples of Ar(g) and Ne(g). For what ratio of absolute temperatures (Ne:Ar) are the average kinetic energies
equal?
A) 0.505
B) 1.00
C) 1.41
D) 1.98
E)
none of these
68.
Which of the following statements is true concerning ideal gases?
A) The temperature of the gas sample is directly related to the average velocity of the gas particles.
B) At STP, 1.0 L of Ar(g) contains about twice the number of atoms as 1.0 L of Ne(g) because the molar mass of Ar is about
twice that of Ne.
C) A gas exerts pressure as a result of the collisions of the gas molecules with the walls of the container.
D) The gas particles in a sample exert attraction on one another.
E)
All of these statements are false.
Use the following to answer questions 69-71:
Samples of the gases H2(g) and SO2(g) have equal masses and are at the same temperature and pressure. Calculate the following:
69.
The ratio of the root-mean-square velocities
A)
B)
C)
D)
E)
1.0
0.18
32
5.6
180
urms (H 2 )
urms (SO 2 )
70.
The ratio of the forces per wall impact
A)
B)
C)
D)
E)
FH
2
F SO
2
1.0
0.18
32
5.6
180
71.
The ratio of average kinetic energies per molecule (H2:SO2)
A) 1.0
B) 0.18
C) 32
D) 5.6
E)
180
Use the following to answer questions 72-73:
Consider two 1.0-L containers, one containing He(g) at 2.50 atm and 24°C and the other containing Ar(g) at 5.00 atm and 48°C.
72.
Calculate the ratio of average velocities (He:Ar).
A) 0.108
B) 0.200
C) 4.98
D) 9.22
E)
none of these
73.
Calculate the ratio of impacts with the wall per second (He:Ar).
A) 1.64
B) 4.98
C) 6.25
D) 9.22
E)
none of these
74.
The root-mean-square velocity of N2 gas at 30°C is
A) 520 m/s.
B) 163 m/s.
C) 51.6 m/s.
D) 16.4 m/s
E)
5.17 m/s
75.
Calculate the temperature at which the average velocity of Ar(g) equals the average velocity of Ne(g) at 25°C.
A) 317°C
B) 151°C
C) 49.5°C
D) 25°C
E)
none of these
76.
Calculate the ratio of the change in momentum per wall impact for Ar(g) to that for He(g) if the gases are at the same
temperature and pressure.
A) 9.98
B) 3.16
C) 0.316
D) 0.100
E)
none of these
77.
The root-mean-square velocity of a gas in a closed container of fixed volume is increased from 345 m/s to 690 m/s. Which one
of the following statements might explain correctly how this change was accomplished?
A) By heating the gas, the temperature was doubled.
B) By pumping out 75% of the gas at constant temperature, the pressure was decreased to 25% of its original value.
C) By heating the gas, the pressure was quadrupled.
D) By pumping in more gas at constant temperature, the pressure was quadrupled.
E)
None of these statements correctly explains the change.
78.
Calculate the temperature at which the average kinetic energy of O2 gas is twice that of He gas at 10.0°C.
A) 2.50°C
B) 10.0°C
C) 20.0°C
D) 160.0°C
E)
293°C
79.
At 200 K, the molecules or atoms of an unknown gas, X, have an average velocity equal to that of Ar atoms at 400 K. What is
X? (Assume ideal behavior.)
A) He
B) CO
C) HF
D) HBr
E)
F2
80.
Consider the following gas samples:
Sample A
Sample B
S2(g)
O2(g)
n = 1 mol
n = 2 mol
T = 800 K
T = 400 K
P = 0.20 atm
P = 0.40 atm
Which one of the following statements is false?
A)
B)
C)
D)
E)
81.
The volume of sample A is twice the volume of sample B.
The average kinetic energy of the molecules in sample A is twice the average kinetic energy of the molecules in sample B.
The fraction of molecules in sample A having a kinetic energies greater than some high fixed value is larger than the
fraction of molecules in sample B having kinetic energies greater than that same high fixed value.
The root-mean-square velocity of molecules in sample A is twice as large as the root-mean-square velocity of molecules
in sample B.
Assuming identical intermolecular forces in the two samples, sample A should be more nearly ideal than sample B.
Order the following according to increasing rate of effusion:
F2, Cl2, NO, NO2, CH4
A)
B)
C)
D)
E)
Cl2
Cl2
CH4
CH4
F2
<
<
<
<
<
NO2
F2
NO2
NO
NO
< F2
< NO2
< NO
< F2
< Cl2
<
<
<
<
<
NO
CH4
F2
NO2
NO2
<
<
<
<
<
CH4
NO
Cl2
Cl2
CH4
Use the following to answer question 82:
Calculate the following ratios for a gas at Kelvin temperatures T1 and T2 where T2 = 2T1.
82.
Effusion rate at T1 : Effusion rate at T2
A) 0.50
B) 2.0
C) 1.0
D) 1.4
E)
0.71
83.
The diffusion rate of H2 gas is 6.45 times as great as that of a certain noble gas (both gases are at the same temperature). What
is the noble gas?
A) Ne
B) He
C) Ar
D) Kr
E)
Xe
84.
A sample of N2 gas is contaminated with a gas (gas A) of unknown molar mass. The partial pressure of each gas is known to be
200. torr at 25°C. The gases are allowed to effuse through a pinhole, and it is found that gas A escapes at 2.65 times the rate of
N2. The molar mass of gas A is
A) 3.99 g/mol.
B) 197 g/mol.
C) 74.2 g/mol.
D) 10.6 g/mol.
E)
none of these
Use the following to answer question 85:
Consider two samples of helium in separate containers of the same volume. Sample 1 has an absolute temperature four times that of
Sample 2. Both samples are at the same pressure.
85.
Calculate the ratio Z1/Z2.
A) 1:1
B) 2:1
C) 4:1
D) 1:4
E)
1:2
86.
Consider two gas samples:
Sample A
Sample B
Contains SF6(g)
Contains SF4(g)
Molar mass = 146
Molar mass = 108
n = 1.00 mol
n = 1.00 mol
V = 1.00 L
V = 1.00 L
T = 50°C
T=?
Calculate the temperature of the SF4(g) sample in which the number of wall impacts per second is the same as in the sample of
SF6(g).
A) -236°C
B) 177 K
C) -34°C
D) 437 K
E)
none of these
Use the following to answer question 87:
Samples of the gases H2(g) and SO2(g) have equal masses and are at the same temperature and pressure. Calculate the following:
87.
The ratio of rates of impact with the walls (H2:SO2)
A) 1.0
B) 0.18
C) 32
D) 5.6
E)
180
88.
Consider two samples of gas at the same volume and temperature that each contains 1.0 mol of gas. Sample A contains H 2 and
sample B contains an unknown gas. The ratio of the impacts per second of gas A with the walls of the container to the impacts
per second of gas B with the walls of the container is 4. Identify gas B.
A) O2
B) Ar
C) He
D) CO2
E)
Ne
Use the following to answer questions 89-90:
Calculate the following ratios for a gas at Kelvin temperatures T1 and T2 where T2 = 2T1.
89.
Mean free path at T1 : Mean free path at T2
A) 0.50
B) 2.0
C) 1.0
D) 1.4
E)
0.71
90.
Collision frequency between O2 molecules at T1 : Collision frequency between O2 molecules at T2
A) 0.50
B) 2.0
C) 1.0
D) 1.4
E)
0.71
Use the following to answer question 91:
Consider three 1-L flasks at the same temperature and pressure. Flask A contains CO gas, flask B contains N 2 gas, and flask C
contains O2 gas.
91.
In which flask do the molecules have the greatest kinetic energy?
A) flask A
B) flask B
C) flask C
D) The molecules in all the flasks have the same kinetic energy.
E)
The molecules in two of the flasks have the same kinetic energy.
Use the following to answer question 92:
Consider three 1.0-L flasks at STP. Flask A contains N2 gas, flask B contains Kr gas, and flask C contains He gas.
92.
In which flask do the gas particles have the highest average velocity?
A) flask A
B) flask B
C) flask C
D) The gas particles in all the flasks have the same average velocity.
E)
The gas particles in two of the flasks have the same average velocity.
93.
How is the observed pressure of a gas related to the ideal pressure?
A) The observed pressure is less than the ideal pressure.
B) The observed pressure is greater than the ideal pressure.
C) They are equal.
D) The relationship depends on the gas.
E)
none of these
94.
How is the volume of the container related to the volume of an ideal gas?
A) The volume of the container is less than the volume of an ideal gas.
B) The volume of the container is more than the volume of an ideal gas.
C) They are equal.
D) The relationship depends on the gas.
E)
none of these
95.
Which gas, He or H2O vapor, has the lower value of a in the van der Waals equation?
A) He
B) H2O
C) The two gases have the same value of a.
D) It depends on the conditions of pressure and temperature.
96.
Which gas, Kr or CO2 , has the lower value of b in the van der Waals equation?
A) Kr
B) CO2
C) The two gases have the same value of b.
D) It depends on the conditions of pressure and temperature.
Answer Key
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
C
B
E
A
C
C
B
D
B
C
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
C
A
E
E
A
A
C
B
C
B
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
A
B
E
B
B
C
A
C
A
D
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
C
D
C
B
B
A
B
A
D
B
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
C
A
D
C
B
C
A
C
D
B
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
E
D
A
C
D
D
E
D
A
E
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
E
C
C
A
D
E
B
C
D
B
71.
72.
73.
74.
75.
76.
77.
78.
79.
80.
A
E
A
A
A
B
C
E
C
D
81.
82.
83.
84.
85.
86.
87.
88.
89.
90.
A
E
D
A
E
C
E
A
C
E
91.
92.
93.
94.
95.
96.
D
C
A
B
A
A