General Chemistry: Atoms First, 2e (McMurry and 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? One atm = 14.70 lb/ .
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.
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) = k
B) = 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, = 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 ?
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 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) 34.4 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 the above
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
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 L of N2 with 6.00
L of H2?
N2(g) + 3 H2(g) → 2 NH3(g)
A) 5.48 L
B) 4.30 L
C) 1.34 L
D) 2.69 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
15
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) Oxygen gas is collected over water in an inverted buret. The atmospheric pressure is 755
mm Hg, the vapor pressure of water is 26 mm Hg, and a 20.0 cm-high column of water remains
in the buret. If the denstity of water is 1.00 g/mL and the density of Hg is 13.6 g/mL, then the
pressure of the oxygen gas is
A) 781mm Hg.
B) 755 mm Hg.
C) 729 mm Hg.
D) 714 mm Hg.
61) 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
62) 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 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
63) 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%
64) 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.
65) 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.
66) 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.
67) 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.
68) 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
69) Which of the following gases has the highest average speed at 400K?
A) CO2
B) N2O4
C) SF6
D) UF6
70) Which of the following gases has the lowest average speed at 25°C?
A) CH4
B) H2S
C) NH3
D) O2
71) 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
72) 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
73) You are given two flasks of equal volume. One contains H2 at 0°C and 1 atm while the other
contains CO2 at 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
74) The mixing of different gases by random molecular motion with frequent collisions is called
A) Avogadro’s law.
B) compressibility.
C) diffusion.
D) effusion.
75) 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.
76) Which one of the following gases will have the highest rate of effusion?
A) NO2
B) N2O
C) N2O4
D) NO3
77) Which one of the following gases will have the lowest rate of effusion?
A) SF4
B) SCl4
C) S2O5
D) SO3
78) 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
79) 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