Chemistry, 6e (McMurry/Fay)
Chapter 9 Gases: Their Properties and Behavior
9.1 Multiple-Choice Questions
1) Carbon dioxide is a gas which causes environmental concern because of the greenhouse effect. What
is the approximate percentage (by volume) of CO2 in the atmosphere?
A) less than 0.1%
B) about 1%
C) about 10%
D) more than 20%
2) Which of the following instruments directly measures the pressure of a gas?
A) spectrometer
B) manometer
C) polarimeter
D) gas chromatograph
3) Pressure is defined as
A) force divided by unit area.
B) force times unit area.
C) mass divided by acceleration.
D) mass times acceleration.
4) The SI unit for pressure is the
A) atmosphere.
B) MM Hg.
C) newton.
D) pascal.
5) Which of the following is not equivalent to 1 atm pressure?
A) 10 cm Hg
B) 14.7 lb/in2
C) 101 kPa
D) 760 mm Hg
6) Which is the smallest quantity of pressure?
A) 1 atm
B) 1 centimeter of Hg
C) 1 mm Hg
D) 1 pascal
7) Automobile tires are typically inflated to about 30 pounds of pressure per square inch. What is the
typical air pressure of a tire in kPa?
A) 2.0 × 10-3 kPa
B) 2.0 kPa
C) 2.1 × 102 kPa
D) 2.1 × 105 kPa
8) The pressure in the eye of a hurricane is less than atmospheric pressure. Which one of the following
pressure readings could not have been taken in the eye of a hurricane?
A) 15 lbs/in2
B) 69 cm Hg
C) 690 mm Hg
D) 9.22 × 104 Pa
9) If mercury (density = 13.6 g/cm3) at a height of 745 mm Hg in a mercury barometer is replaced with
water (density = 1.00 g/cm3), under the same conditions the height of water will be
A) 0.180 ft
B) 2.44 ft
C) 33.2 ft
D) 399 ft
10) Suppose you needed to closely monitor small changes in pressure inside a container using an open
end manometer. For the best accuracy, the substance in the manometer should
A) be a solid.
B) be mercury.
C) have a high density.
D) have a low density.
3
11) In an open end manometer, one end of a U-tube filled with mercury is attached to a gas-filled
container and the other end is open to the atmosphere. If the gas pressure in the container is less than
atmospheric pressure
A) Hg will be forced out of the open end of the U-tube.
B) the difference between the Hg levels in the two arms will be greater than 76 cm.
C) the Hg level will be higher in the arm connected to the container.
D) the Hg level will be higher in the arm open to the atmosphere.
12) What is the pressure in a gas container that is connected to an open-end U-tube manometer if the
pressure of the atmosphere is 752 torr and the level of mercury in the arm connected to the container is
8.60 cm higher than the level of mercury open to the atmosphere?
A) 666 mm Hg
B) 743 mm Hg
C) 761 mm Hg
D) 838 mm Hg
13) If the pressure in a gas container that is connected to an open-end U-tube manometer is 106 kPa and
the pressure of the atmosphere at the open end of the tube is 742 mm Hg, the level of mercury in the
tube will be
A) 53 mm higher in the arm open to the atmosphere.
B) 53 mm higher in the arm connected to the gas cylinder.
C) 636 mm higher in the arm open to the atmosphere.
D) 636 mm higher in the arm connected to the gas cylinder.
14) A container filled with gas is connected to an open-end U-tube manometer that is filled with mineral
oil. The pressure in the gas container is 773 mm Hg and atmospheric pressure is 754 mm Hg. What will
be the difference in the levels of mineral oil in the two arms of the manometer if the densities of Hg and
mineral oil are 13.6 g/mL and 0.822 g/mL respectively?
A) 1.15 mm
B) 15.6 mm
C) 19.0 mm
D) 314 mm
15) Which one of the following is not used to describe the condition of a gas?
A) number of moles
B) polarity
C) temperature
D) volume
16) Which of the following equations represents “Boyle’s law”?
A)
P
V
= k
B)
V
T
= k
C) PV = k
D) V = nk
17) When pressure-volume measurements are made on 1.0 mol of gas at constant temperature, a plot V
versus P results in a
A) hyperbola.
B) parabola.
C) sine curve.
D) straight line.
18) When temperature-volume measurements are made on 1.0 mol of gas at 1.0 atm, a plot V versus T
results in a
A) hyperbola.
B) parabola.
C) sine curve.
D) straight line.
19) Which law does the equation,
V
n
= k represent?
A) Avogadro’s law
B) Boyle’s law
C) Charles’ law
D) Graham’s law
20) An approximation of absolute zero was made from an extrapolation of
A) P vs. 1/V
B) V vs. T
C) n vs. V
D) V vs. 1/T
21) “Equal volumes of different gases at the same temperature and pressure contain the same molar
amounts” is another way of stating
A) Avogadro’s law.
B) Boyle’s law.
C) Charles’ law.
D) Graham’s law.
22) An “empty” aerosol can at 25°C still contains gas at 1.00 atmosphere pressure. If an “empty” can is
thrown into a 475°C fire, what is the final pressure in the heated can?
A) 5.26 × 10-2 atm
B) 0.398 atm
C) 2.51 atm
D) 19.0 atm
23) A basketball is inflated to a pressure of 1.50 atm in a 20.0°C garage. What is the pressure of the
basketball outside where the temperature is -5.00°C?
A) 1.37 atm
B) 1.42 atm
C) 1.58 atm
D) 1.64 atm
24) A gas bottle contains 0.650 mol of gas at 730 mm Hg pressure. If the final pressure is 1.15 atm, how
many moles of gas were added to the bottle?
A) 0.0680 mol
B) 0.128 mol
C) 0.717 mol
D) 0.778 mol
25) The volume of 350. mL of gas at 25°C is decreased to 125 mL at constant pressure. What is the final
temperature of the gas?
A) -167°C
B) 8.9°C
C) 70°C
D) 561°C
26) A balloon filled with helium gas at 20°C occupies 2.91 L at 1.00 atm. The balloon is immersed in
liquid nitrogen at -196°C, raising the pressure to 5.20 atm. What is the volume of the balloon in the
liquid nitrogen?
A) 0.15 L
B) 2.1 L
C) 4.0 L
D) 58 L
27) What is the value of the gas constant, R, in units of
3
mm Hg cm
mol K
?
A) 1.080 × 10-4
B) 0.1080
C) 62.36
D) 6.236 × 104
28) If the number of moles of gas is doubled at constant temperature and volume, the pressure of the gas
A) is halved.
B) is doubled.
C) is quadrupled.
D) remains the same.
29) Three identical flasks contain three different gases at standard temperature and pressure. Flask A
contains CH4, flask B contains CO2, flask C contains N2. Which flask contains the largest number of
molecules?
A) flask A
B) flask B
C) flask C
D) All flasks contain the same number of molecules.
30) How many molecules of N2 are in a 500.0 mL container at 780 mm Hg and 135°C?
A) 8.76 × 1021
B) 9.23 × 1021
C) 2.65 × 1022
D) 2.79 × 1022
31) A 1.75 L container filled with CO2 gas at 25°C and 225 kPa pressure springs a leak. When the
container is re-sealed, the pressure is 185 kPA and the temperature is 10°C. How many moles of gas
were lost?
A) 0.0213 mol
B) 0.463 mol
C) 0.561 mol
D) 2.16 mol
32) A 75.0 L steel tank at 20.0°C contains acetylene gas, C2H2, at a pressure of 1.39 atm. Assuming
ideal behavior, how many grams of acetylene are in the tank?
A) 4.33 g
B) 6.01 g
C) 113 g
D) 1650 g
33) A 1.00 L flask contains nitrogen gas at 25°C and 1.00 atm pressure. What is the final pressure in the
flask if an additional 2.00 g of N2 gas is added to the flask and the flask cooled to -55°C?
A) 1.28 atm
B) 2.01 atm
C) 2.56 atm
D) 3.29 atm
34) A steel bottle contains argon gas at STP. What is the final pressure if the temperature is changed to
115°C?
A) 0.704 atm
B) 0.768 atm
C) 1.30 atm
D) 1.42 atm
35) A gas occupies 22.4 L at STP and 14.5 L at 100°C and 2.00 atm pressure. How many moles of gas
did the system gain or lose?
A) 0.06 moles gained
B) 0.03 moles gained
C) 0.03 moles lost
D) 0.05 moles lost
36) How many grams of O2 gas are there in a 5.00-L cylinder at 4.00 × 103 mm Hg and 23°C?
A) 17.3 g
B) 34.7 g
C) 446 g
D) 2.63 × 104 g
37) What is the volume of 10.0 g of argon gas at 157°C and 2.50 kPa pressure?
A) 1.29 L
B) 3.53 L
C) 131 L
D) 358 L
38) What is the Celsius temperature of 100.0 g of chlorine gas in a 40.0-L container at 800 mm Hg?
A) -91°C
B) 91°C
C) 182°C
D) 364°C
39) Cyanogen is a gas which contains 46.2% C and 53.8% N by mass. At a temperature of 25°C and a
pressure of 750 mm Hg, 1.50 g of cyanogen occupies 0.714 L. What is the molecular formula of
cyanogen?
A) CN
B) C2N2
C) C3N4
D) C4N5
40) A 0.286-g sample of gas occupies 125 mL at 60. cm of Hg and 25°C. What is the molar mass of the
gas?
A) 5.9 g/mol
B) 44 g/mol
C) 59 g/mol
D) 71 g/mol
41) What is the density of fluorine gas at STP?
A) 0.590 g/L
B) 0.848 g/L
C) 1.55 g/L
D) 1.70 g/L
42) One mole of which gas has the greatest density at STP?
A) Ar
B) N2
C) CO
D) All three gases have the same density.
43) Which of the following would have a density of 1.21 g/L at 7.0°C and 0.987 atm?
A) Ar
B) N2
C) Ne
D) O2
44) Given three cylinders containing O2 gas at the same volume and pressure. Cylinder A is at -20°C,
cylinder B is at -15°F, cylinder C is at 260 K. Which cylinder contains the largest mass of oxygen?
A) cylinder A
B) cylinder B
C) cylinder C
D) All cylinders contain the same mass of O2.
45) Chloroform is a volatile liquid once commonly used in the laboratory but now being phased out due
to its ozone depletion potential. If the pressure of gaseous chloroform in a flask is 195 mm Hg at 25°C
and its density is 1.25 g/L, what is the molar mass of chloroform?
A) 10.0 g/mol
B) 76.3 g/mol
C) 119 g/mol
D) None of these
46) The action of some commercial drain cleaners is based on the following reaction:
2 NaOH(s) + 2 Al(s) + 6 H2O(l) → 2 NaAl(OH)4(s) + 3 H2(g)
What is the volume of H2 gas formed at STP when 4.32 g of Al reacts with excess NaOH?
A) 2.39 L
B) 3.59 L
C) 5.38 L
D) 5.87 L
47) At STP how many grams of Mg are required to produce 35 mL of H2 in the reaction shown below?
Mg(s) + 2 HCl(aq) → H2(g) + MgCl2(aq)
A) 0.035 g
B) 0.038 g
C) 26 g
D) 29 g
48) When 15.0 g of zinc metal reacts with excess HCl, how many liters of H2 gas are produced at STP?
A) 0.229 L
B) 0.458 L
C) 5.14 L
D) 10.3 L
49) A lungful of air (500 mL) contains 4.1% CO2 by volume. How many grams of KO2(s) is needed to
remove the CO2 from a lungful of air at STP according to the following reaction?
4 KO2(s) + 2 CO2(g) → 2 K2CO3(s) + 3 O2(g)
A) 0.065 g
B) 0.13 g
C) 0.26 g
D) 1.2 g
50) How many liters of oxygen are needed to exactly react with 27.8 g of methane at STP?
CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l)
A) 19.5 L
B) 39.0 L
C) 77.6 L
D) 85.0 L
11
51) How many grams of XeF6 are required to react with 0.579 L of hydrogen gas at 2.46 atm and 45°C
in the reaction shown below?
XeF6(s) + 3 H2(g) → Xe(g) + 6 HF(g)
A) 3.65 g
B) 4.46 g
C) 13.4 g
D) 40.2 g
52) How many liters of SO3(g) are produced at 25°C and 1.00 atm from the combustion of 1.00 kg of
coal which is 1.00% S by weight? Assume all the sulfur in the coal ends up as SO3.
A) 0.640 L
B) 5.08 L
C) 7.63 L
D) 11.4 L
53) At STP how many liters of NH3 can be produced from the reaction of 6.00 mol of N2 with 6.00 mol
of H2?
N2(g) + 3 H2(g) → 2 NH3(g)
A) 44.8 L
B) 89.6 L
C) 134 L
D) 269 L
54) A 10.0-L flask containing He, 2.00 mole of Ar, and 3.00 mole of Ne has a total pressure of 24.5 atm
at 25°C. How many moles of He are in the flask?
A) 5.00 mol
B) 10.0 mol
C) 114 mol
D) 119 mol
55) A balloon contains 0.76 mol N2, 0.18 mol O2, 0.031 mol He, and 0.026 mol H2 at 739 mm Hg.
What is the partial pressure of O2?
A) 19 mm Hg
B) 23 mm Hg
C) 130 mm Hg
D) 560 mm Hg
56) What is the total pressure in a 10.0 L flask which contains 0.127 mol of H2(g) and 0.288 mol of
N2(g) at 20.0°C?
A) 0.306 atm
B) 0.681 atm
C) 0.693 atm
D) 0.998 atm
57) A 1.000 kg sample of nitroglycerine, C3H5N3O9, explodes and releases gases with a temperature of
1985°C at 1.000 atm. What is the volume of gas produced?
4 C3H5N3O9(l) → 12 CO2(g) + 10 H2O(g) + 6 N2(g) + O2(g)
A) 816.4 L
B) 3878 L
C) 5203 L
D) 5919 L
58) If the Earth’s ozone (O3) layer has a total volume of 1.00 × 1020 km3, a partial pressure of 1.6 × 10–
9 atm, and an average temperature of 230 K, how many ozone molecules are in the Earth’s ozone layer?
A) 2.3 × 1035 molecules
B) 5.1 × 1035 molecules
C) 2.3 × 1045 molecules
D) 5.1 × 1045 molecules
59) Hydrogen gas is collected over water in an inverted buret. If the atmospheric pressure is 745 mm
Hg, the vapor pressure of water is 18 mm Hg, and a 15.0 cm-high column of water remains in the buret,
the pressure of the hydrogen gas is
A) 763 mm.
B) 745 mm Hg.
C) 727 mm Hg.
D) less than 727 mm Hg.
60) In the laboratory, hydrogen gas is usually made by the following reaction:
Zn(s) + 2 HCl(aq) → H2(g) + ZnCl2(aq)
How many liters of H2 gas, collected over water at an atmospheric pressure of 752 mm Hg and a
temperature of 21.0°C, can be made from 1.566 g of Zn and excess HCl? The partial pressure of water
vapor is 18.65 mm Hg at 21.0°C.
A) 0.0428 L
B) 0.573 L
C) 0.585 L
D) 0.599 L
61) The ozone molecules in the stratosphere absorb much of the ultraviolet radiation from the sun,
protecting life on Earth. At a certain altitude, the temperature of the stratosphere is 240 K and the partial
pressure of ozone is 1.4 × 10-7 atm. Calculate the number of ozone molecules present in 1.00 L of
atmosphere at that altitude.
A) 2.1 × 1015 molecules of O3
B) 4.3 × 1015 molecules of O3
C) 8.0 × 1031 molecules of O3
D) 1.8 × 1032 molecules of O3
62) A 0.500 g sample containing Ag2O and inert material is heated, causing the silver oxide to
decompose according to the following equation:
2 Ag2O(s) → 4 Ag(s) + O2(g)
If 13.8 mL of gas are collected over water at 27°C and 1.00 atm external pressure, what is the percentage
of silver oxide in the sample? The partial pressure of water is 26.7 mm Hg at 27°C.
A) 12.5%
B) 25.1%
C) 50.1%
D) 51.9%
63) Some assumptions from the kinetic molecular theory are listed below. Which one is most frequently
cited to explain Charles’ law?
A) The average kinetic energy of gas particles is proportional to the Kelvin temperature.
B) Collisions of gas particles are elastic and total kinetic energy of the gas is constant.
C) A gas consists of tiny particles moving in random straight line motion.
D) The volume of the particles is negligible compared to the volume of the gas.
64) Some assumptions from the kinetic molecular theory are listed below. Which one is most frequently
cited to explain compressibility of a gas?
A) The average kinetic energy of gas particles is proportional to the Kelvin temperature.
B) Collisions of gas particles are elastic and total kinetic energy of the gas is constant.
C) A gas consist of tiny particles moving in random straight line motion.
D) The volume of the particles is negligible compared to the volume of the gas.
65) Some assumptions from the kinetic molecular theory are listed below. Which one is most frequently
cited to explain diffusion of a gas?
A) The average kinetic energy of gas particles is proportional to the Kelvin temperature.
B) Collisions of gas particles are elastic and total kinetic energy of the gas is constant.
C) A gas consist of tiny particles moving in random straight line motion.
D) The volume of the particles is negligible compared to the volume of the gas.
66) According to the kinetic molecular theory, the pressure of a gas in a container will decrease if the
A) number of collisions with the container wall increases.
B) number of moles of the gas increases.
C) temperature of the gas decreases.
D) volume of the container decreases.
67) What is the average speed (actually the root-mean-square speed) of a neon atom at 27°C?
A) 5.78 m/s
B) 19.3 m/s
C) 183 m/s
D) 609 m/s
68) Which of the following gases has the highest average speed at 400K?
A) CO2
B) N2O4
C) SF6
D) UF6
69) Which of the following gases has the lowest average speed at 25°C?
A) CH4
B) H2S
C) NH3
D) O2
70) What is the temperature of CO2 gas if the average speed (actually the root-mean-square speed) of
the molecules is 750 m/s?
A) 1.32 K
B) 9.92 × 102 K
C) 1.31 × 103 K
D) 9.92 × 105 K
71) At what temperature will sulfur hexafluoride molecules have the same average speed as argon atoms
at 20°C?
A) -22.0°C
B) 73.2°C
C) 381°C
D) 799°C
72) You are given two flasks of equal volume. One contains H2 at 0°C and 1 atm while the other
contains CO2 at 0°C and 2 atm. Which of the following quantities will be the same for both flasks?
A) average molecular kinetic energy
B) average molecular speed
C) density
D) number of molecules present
73) Each of three identical 15.0-L gas cylinders contains 7.50 mol of gas at 295 K. Cylinder A contains
Ar, cylinder B contains Cl2, and cylinder C contains N2. According to the kinetic molecular theory,
which gas has the highest collision frequency?
A) Ar
B) Cl2
C) N2
D) All have identical collision frequencies
74) Each of three identical 15.0-L gas cylinders contains 7.50 mol of gas at 295 K. Cylinder A contains
Ar, cylinder B contains Cl2, and cylinder C contains N2. According to the kinetic molecular theory,
which gas has the highest average speed?
A) Ar
B) Cl2
C) N2
D) All have identical average speeds
75) Each of three identical 15.0-L gas cylinders contains 7.50 mol of gas at 295 K. Cylinder A contains
Ar, cylinder B contains Cl2, and cylinder C contains N2. According to the kinetic molecular theory,
which gas has the highest pressure?
A) Ar
B) Cl2
C) N2
D) All have identical pressures
76) Each of three identical 15.0-L gas cylinders contains 7.50 mol of gas at 295 K. Cylinder A contains
Ar, cylinder B contains Cl2, and cylinder C contains N2. According to the kinetic molecular theory,
which gas has the highest density?
A) Ar
B) Cl2
C) N2
D) All have identical densities
77) Each of three identical 15.0-L gas cylinders contains 7.50 mol of gas at 295 K. Cylinder A contains
Ar, cylinder B contains Cl2, and cylinder C contains N2. According to the kinetic molecular theory,
which gas has the highest average kinetic energy?
A) Ar
B) Cl2
C) N2
D) All have identical average kinetic energies
78) The mixing of different gases by random molecular motion with frequent collisions is called
A) Avogadro’s law.
B) compressibility.
C) diffusion.
D) effusion.
79) A process by which gas molecules escape through a tiny hole in a membrane into a vacuum without
collisions is called
A) Boyle’s law.
B) diffusion.
C) effusion.
D) sublimation.
80) Which one of the following gases will have the highest rate of effusion?
A) NO2
B) N2O
C) N2O4
D) NO3
81) Which one of the following gases will have the lowest rate of effusion?
A) SF4
B) SCl4
C) S2O5
D) SO3
82) An unknown gas effuses 1.73 times faster than krypton. What is the molar mass of the gas?
A) 28.0 g/mol
B) 48.4 g/mol
C) 110 g/mol
D) 251 g/mol
83) An unknown gas effuses 2.3 times faster than N2O4 at the same temperature. What is the identity of
the unknown gas?
A) CN2
B) NH3
C) N2O
D) O3
84) If CO2 and NH3 are allowed to effuse through a porous membrane under identical conditions, the
rate of effusion for NH3 will be ________ times that of CO2.
A) 0.39
B) 0.62
C) 1.6
D) 2.6
85) An unknown gas contains 83% C and 17% H by mass. If effuses at 0.87 times the rate of CO2 gas
under the same conditions. What is the molecular formula of the unknown gas?
A) C2H5
B) C3H3
C) C4H10
D) C7H17
86) Which of the noble gases should show the greatest deviation from the ideal gas law at high
pressures?
A) He
B) Ar
C) Rn
D) All deviate equally.
87) Which statement about real gases is true?
A) The volume of the gas particles is zero.
B) The mass of the gas particles is zero.
C) Forces of attraction and repulsion exist between gas particles at close range.
D) The behavior of real gases can be exactly predicted using the ideal gas law.
88) Which of the following regions of the earth’s atmosphere is farthest from the surface of the earth?
A) mesosphere
B) stratosphere
C) thermosphere
D) troposphere
89) The lowest atmospheric temperatures are found at the
A) earths surface.
B) troposphere/stratosphere junction.
C) stratosphere/mesosphere junction.
D) mesosphere/thermosphere junction.
90) Which of the following regions of the earth’s atmosphere is closest to the surface of the earth?
A) mesosphere
B) stratosphere
C) thermosphere
D) troposphere
91) Which of the following regions of the earth’s atmosphere contains the ozone layer?
A) mesosphere
B) stratosphere
C) thermosphere
D) troposphere
92) One reaction that contributes to photochemical smog is shown below. Which of the species involved
contains one or more unpaired electrons?
NO2(g) + hυ →NO(g) + O(g)
A) only NO2(g)
B) only NO2(g) and NO(g)
C) only O(g)
D) All of the these contain unpaired electrons.
93) Which of the following is the principal cause of global warming?
A) acid rain
B) air pollution
C) greenhouse effect
D) ozone depletion
94) Which of the following substances has increased markedly due to the use of fossil fuels and
contributes to the greenhouse effect?
A) CO2
B) SO2
C) NO2
D) O3
95) The principal cause of man-made ozone depletion in the stratosphere is due to
A) NO2.
B) CH4.
C) CO2.
D) Cl.
96) The major source of Cl atoms in the stratosphere is from
A) CFC’s.
B) NaCl.
C) Cl2.
D) HCl.
97) An unusual correlation exists between the potency of an inhaled anesthetic and its ability to
A) dissolve in olive oil.
B) effuse through a porous membrane.
C) expand and compress.
D) react with ozone.