Chapter 5 2 What is the final pressure if the temperature is changed

36) Give the temperature and pressure at STP.

A) 0°C and 1.00 atm

B) 0K and 1.00 atm

C) 25°C and 1.00 in Hg

D) 32K and 1 torr Hg

E) 0°C and 1 mm Hg

37) Which of the following gas samples would be most likely to behave ideally under the stated

conditions?

A) Ar at STP

B) CO at 200 atm and 25°C

C) SO2 at 2 atm and 0 K

D) N2 at 1 atm and -70°C

E) H2 at 400 atm and 25°C

38) Which of the following samples will have the greatest volume at STP?

A) 22 g Ne

B) 22 g He

C) 22 g O2

D) 22 g Cl2

E) All of these samples would have the same volume at STP.

39) Which of the following samples will have the lowest pressure if they are all at the same temperature

and in identical containers (same volume)?

A) 15 g H2

B) 15 g Ar

C) 15 g Kr

D) 15 g CO2

E) All of these samples will have the same pressure.

40) Which of the following samples has the greatest density at STP?

A) NO2

B) Xe

C) SO2

D) SF6

E) All of these samples have the same density at STP.

41) Place the following gases in order of increasing density at STP.

F2 NH3 N2O4 Ar

A) N2O4 < Ar < F2 < NH3

B) Ar < N2O4 < F2 < NH3

C) F2 < Ar < N2O4 < NH3

D) NH3 < F2 < Ar < N2O4

E) Ar < F2 < NH3 < N2O4

42) The density of a gas is 3.16 g/L at STP. What is the gas?

A) H2

B) Br2

C) Kr

D) Cl2

E) Ar

43) What volume will 4.91 x 1022 atoms of Ar occupy at STP?

A) 1.10 L

B) 2.00 L

C) 2.24 L

D) 3.11 L

E) 1.83 L

44) What volume will 0.780 moles of Xe occupy at STP?

A) 22.4 L

B) 70.0 L

C) 43.7 atm

D) 17.5 L

E) 15.6 L

45) A steel bottle contains argon gas at STP. What is the final pressure if the temperature is changed to

145°C?

A) 0.653 atm

B) 0.713 atm

C) 1.40 atm

D) 1.53 atm

46) A gas occupies 22.4 L at STP and 19.0 L at 100°C and 1.50 atm pressure. How many moles of gas

did the system gain or lose?

A) 0.08 moles gained

B) 0.01 moles gained

C) 0.01 moles lost

D) 0.07 moles lost

47) What is the density of hydrogen gas at STP?

A) 11.1 g/L

B) 0.0450 g/L

C) 0.0823 g/L

D) 0.0899 g/L

48) Which of the following would have a density of 1.37 g/L at 7.0°C and 0.987 atm?

A) N2

B) O2

C) Kr

D) Rn

49) The density of chlorine gas at 1.21 atm and 34.9°C is ________ g/L.

A) 0.0479

B) 0.295

C) 0.423

D) 1.70

E) 3.39

50) 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

51) Given three cylinders containing O2 gas at the same volume and pressure. Cylinder A is at -15°C,

cylinder B is at -5°F, cylinder C is at 255 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.

52) A 1.44-g sample of an unknown pure gas occupies a volume of 0.335 L at a pressure of 1.00 atm and

a temperature of 100.0°C. The unknown gas is ________.

A) argon

B) helium

C) krypton

D) neon

E) xenon

53) Give the gas that is the lowest percent by volume in dry gas.

A) CO2

B) He

C) H2

D) N2

54) In a container containing CO, H2, and O2, what is the mole fraction of CO if the H2 mole fraction is

0.22 and the O2 mole fraction is 0.58?

A) 0.20

B) 0.30

C) 0.10

D) 0.50

55) A mixture of 0.220 moles CO, 0.350 moles H2 and 0.640 moles He has a total pressure of 2.95 atm.

What is the pressure of H2?

A) 1.17 atm

B) 0.853 atm

C) 1.03 atm

D) 0.969 atm

E) 0.649 atm

56) A mixture of 0.220 moles CO, 0.350 moles N2 and 0.640 moles Ne has a total pressure of 2.95 atm.

What is the pressure of CO?

A) 1.86 atm

B) 0.649 atm

C) 0.536 atm

D) 1.54 atm

E) 0.955 atm

57) A mixture of N2, O2 and He have mole fractions of 0.25, 0.65, and 0.10, respectively. What is the

pressure of N2 if the total pressure of the mixture is 3.9 atm?

A) 2.5 atm

B) 0.39 atm

C) 0.67 atm

D) 0.98 atm

E) 1.33 atm

58) A mixture of Ar, Ne and He has a pressure of 7.85 atm. If the Ne has a mole fraction of 0.47 and He

has a mole fraction of 0.23, what is the pressure of Ar?

A) 4.2 atm

B) 3.7 atm

C) 1.8 atm

D) 5.5 atm

E) 2.4 atm

59) A gas mixture contains CO, Ar and H2. What is the total pressure of the mixture, if the mole

fraction of H2 is 0.350 and the pressure of H2 is 0.480 atm?

A) 1.37 atm

B) 0.168 atm

C) 5.95 atm

D) 0.729 atm

E) 2.1 atm

60) The mole fraction of argon in dry air near sea level is 1.818 × 10-5 where the molar mass of argon is

39.948. The concentration of argon in the atmosphere is ________ ppm.

A) 1.07 × 108

B) 0.934

C) 9.34 × 106

D) 18.18

E) 9.34 × 109

25

61) A balloon contains 0.76 mol N2, 0.18 mol O2, 0.031 mol He and 0.026 mol H2 at 749 mm Hg.

What is the partial pressure of O2?

A) 20 mm Hg

B) 23 mm Hg

C) 140 mm Hg

D) 570 mm Hg

62) What is the total pressure in a 6.00-L flask which contains 0.127 mol of H2(g) and 0.288 mol of

N2(g) at 20.0°C?

A) 0.510 atm

B) 0.681 atm

C) 1.16 atm

D) 1.66 atm

63) The concentration of water vapor in a sample of air that has a partial pressure of water of 0.91 torr

and a total pressure of air of 735 torr is ________ ppm.

A) 1.2 × 103

B) 1.2

C) 0.12

D) 8.1 × 10-4

E) 0.81

64) A sample of air from a home is found to contain 6.2 ppm of carbon monoxide. This means that if

the total pressure is 695 torr, then the partial pressure of CO is ________ torr.

A) 4.3 × 103

B) 4.3 × 10-3

C) 4.3

D) 8.9 × 103

E) 1.1 × 108

65) The concentration of ozone in a sample of air that has a partial pressure of of 0.33 torr and a total

pressure of air of 735 torr is ________ ppm.

A) 4.5 × 102

B) 0.45

C) 0.045

D) 2.2 × 10-3

E) 2.2

66) The mole fraction of carbon dioxide in dry air near sea level is 0.000375, where the molar mass of

carbon dioxide is 44.010. The partial pressure of carbon dioxide when the total atmospheric pressure

(dry air) is 97.5 kPa is ________ kPa.

A) 2.63 × 105

B) 5.97 × 103

C) 0.0370

D) 1.63

E) 8.40 × 10-4

67) 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 3.566 g of Zn and excess HCl? The partial pressure of water

vapor is 18.65 mm Hg at 21.0°C.

A) 0.0975 L

B) 1.30 L

C) 1.33 L

D) 1.36 L

68) A 0.600 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) 10.4%

B) 20.9%

C) 41.8%

D) 44.8%

69) Zinc reacts with aqueous sulfuric acid to form hydrogen gas:

Zn(s) + H2SO4 (aq) → ZnSO4 (aq) + H2 (g)

In an experiment, 225 mL of wet H2 is collected over water at 27°C and a barometric pressure of 748

torr. How many grams of Zn have been consumed? The vapor pressure of water at 27°C is 26.74 torr.

A) 4.79 × 106

B) 0.567

C) 567

D) 431

E) 4.31 × 105

70) Zinc reacts with aqueous sulfuric acid to form hydrogen gas:

Zn(s) + H2SO4 (aq) → ZnSO4 (aq) + H2 (g)

In an experiment, 201 mL of wet H2 is collected over water at 27°C and a barometric pressure of 733

torr. The vapor pressure of water at 27°C is 26.74 torr. The partial pressure of hydrogen in this

experiment is ________ atm.

A) 0.929

B) 706

C) 0.964

D) 760

E) 1.00

71) The mole fraction of oxygen in dry air near sea level is 0.20948. The concentration of oxygen is

________ molecules per liter, assuming an atmospheric pressure of 739 torr and a temperature of

29.5°C.

A) 6.23

B) 0.00819

C) 4.93 × 1021

D) 3.75 × 1024

E) 5.07 × 1022

72) The concentration of carbon monoxide in a sample of air is 9.2 ppm. There are ________ molecules

of CO in 1.00 L of this air at 755 torr and 23°C.

A) 3.8 × 10-7

B) 2.2 × 1021

C) 2.9 × 1018

D) 1.7 × 1020

E) 2.3 × 1017

73) 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 6.32 g of Al reacts with excess NaOH?

A) 3.50 L

B) 5.25 L

C) 7.87 L

D) 8.59 L

74) How many liters of oxygen are needed to exactly react with 19.8 g of methane at STP?

CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l)

A) 13.9 L

B) 27.8 L

C) 55.5 L

D) 60.5 L

75) When 14.0 g of zinc metal reacts with excess HCl, how many liters of H2 gas are produced at STP?

A) 0.208 L

B) 0.416 L

C) 4.80 L

D) 9.60 L

76) How many grams of XeF6 are required to react with 0.579 L of hydrogen gas at 6.46 atm and 45°C

in the reaction shown below?

XeF6(s) + 3 H2(g) → Xe(g) + 6 HF(g)

A) 9.58 g

B) 11.7 g

C) 35.2 g

D) 106 g

77) A 1.000 kg sample of nitroglycerine, C3H5N3O9, explodes and releases gases with a temperature of

1985°C at 1.100 atm. What is the volume of gas produced?

4 C3H5N3O9(s) → 12 CO2(g) + 10 H2O(g) + 6 N2(g) + O2(g)

A) 742.2 L

B) 3525 L

C) 4730 L

D) 5378 L

78) Calcium hydride (CaH2) reacts with water to form hydrogen gas:

CaH2(s) + 2H2O(l) → Ca(OH)2(aq) + 2H2(g)

How many grams of CaH2 are needed to generate 48.0 L of H2 gas at a pressure of 0.888 atm and a

temperature of 32°C?

A) 50.7

B) 0.851

C) 143

D) 35.8

E) 71.7

79) How many grams of zinc metal are required to produce 2.00 liters of hydrogen gas at STP according

to the chemical equation shown below?

Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g)

A) 0.171 g

B) 5.83 g

C) 11.7 g

D) 131 g

80) How many grams of calcium hydride are required to produce 4.56 L of hydrogen gas at 25.0°C and

0.975 atm pressure according to the chemical equation shown below?

CaH2(s) + 2 H2O(l) → Ca(OH)2(aq) + 2 H2(g)

A) 3.82 g

B) 7.64 g

C) 15.3 g

D) 45.6 g

81) How many liters of hydrogen gas can be generated by reacting 9.25 grams of barium hydride with

water at 20°C and 755 mm Hg pressure according to the chemical equation shown below?

BaH2(s) + 2 H2O(l) → Ba(OH)2(aq) + 2 H2(g)

A) 0.219 L

B) 0.799 L

C) 1.60 L

D) 3.21 L

82) How many grams of water are required to produce 5.50 L of hydrogen gas at 25.0°C and 755 mm

Hg pressure according to the chemical equation shown below?

BaH2(s) + 2 H2O(l) → Ba(OH)2(aq) + 2 H2(g)

A) 2.01 g

B) 4.02 g

C) 4.07 g

D) 8.04 g

83) How many liters of hydrogen gas are needed to produce 100.0 grams of water at 25.0°C and 1.00

atm pressure according to the chemical equation shown below?

2 H2(g) + O2(g) → 2 H2O(l)

A) 67.9 L

B) 136 L

C) 203 L

D) 407 L

84) What is the total volume of the mixture of hydrogen gas and oxygen gas can be obtained from the

electrolysis of 110.0 grams of water at 25.0°C and 1.00 atm pressure according to the chemical equation

shown below?

2 H2O(l) → 2 H2(g) + O2(g)

A) 74.7 L

B) 149 L

C) 224 L

D) 447 L

85) How many mL of O2 gas at 25°C and 755 mm Hg pressure can be produced from the thermal

decomposition of 0.300 grams of KClO3(s) according to the chemical equation shown below?

2 KClO3(s) → 2 KCl(s) + 3 O2(g)

A) 30.1 mL

B) 40.2 mL

C) 90.4 mL

D) 181 mL

86) How many grams of KCl(s) are produced from the thermal decomposition of KClO3(s) which

produces 50.0 mL of O2(g) at 25°C and 1.00 atm pressure according to the chemical equation shown

below?

2 KClO3(s) → 2 KCl(s) + 3 O2(g)?

A) 0.102 g

B) 0.152 g

C) 0.167 g

D) 0.304 g

87) How many liters of oxygen gas can be produced at STP from the decomposition of 0.250 L of 3.00

M H2O2 in the reaction according to the chemical equation shown below?

2 H2O2(l) → 2 H2O(l) + O2(g)

A) 8.41 L

B) 11.2 L

C) 16.8 L

D) 33.6 L

88) What is the total volume of hydrogen gas and oxygen gas that can be produced from the thermal

decomposition of 0.0425 grams of H2O2 at 700°C and 755 mm Hg according to the chemical equation

shown below?

H2O2(l) → H2(g) + O2(g)?

A) 50.2 mL

B) 100 mL

C) 151 mL

D) 201 mL

89) How many liters of O2 gas at 25°C and 1.00 atm pressure are needed to react with 60.25 grams of

potassium hydride according to the chemical equation shown below?

2 KH(s) + O2(g) → H2O(l) + K2O(s)

A) 9.19 L

B) 18.4 L

C) 36.8 L

D) 73.5 L

90) How many milliliters of ozone gas at at 25.0°C and 1.00 atm pressure are needed to react with 45.00

mL of a 0.100 M aqueous solution of KI according to the chemical equation shown below?

O3(g) + 2 I–(aq) + H2O(l) → O2(g) + I2(s) + 2 OH–(aq)

A) 55.0 mL

B) 110. mL

C) 165 mL

D) 220. mL

91) Identify the gas particle that travels the fastest.

A) H2

B) N2

C) Ne

D) Cl2

E) CO

92) Identify the gas particle that travels the slowest.

A) H2

B) N2

C) Ne

D) F2

E) CO

93) 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

94) Which of the following gases has the highest average speed at 400K?

A) N2

B) O2

C) F2

D) Cl2

95) Which of the following gases has the lowest average speed at 25°C?

A) C3H8

B) Kr

C) CH3NH2

D) SO2

96) What is the temperature of NO2 gas if the average speed (actually the root-mean-square speed) of

the molecules is 750 m/s?

A) 1.38 K

B) 1.04 × 103 K

C) 1.38 × 103 K

D) 1.04 × 106 K

97) If NO and NH3 are allowed to effuse through a porous membrane under identical conditions, the

rate of effusion for NH3 will be ________ times that of NO .

A) 0.57

B) 0.75

C) 1.3

D) 1.8

98) Rank the following in order of decreasing rate of effusion.

F2 SF6 He Ar

A) SF6 > Ar > F2 > He

B) Ar > He > SF6 > F2

C) F2 > Ar > He > SF6

D) He > F2 > Ar > SF6

E) He > F2 > SF6 > Ar

99) Calculate the ratio of effusion rates of Cl2 to O2.

A) 47.7

B) 0.451

C) 2.22

D) 1.49

E) 0.671

100) A sample of N2 effuses in 220 s. How long will the same size sample of Cl2 take to effuse?

A) 350 s

B) 138 s

C) 558 s

D) 86.8 s

E) 388 s

101) Which of the following samples will have the greatest average speed at 355 K?

A) Kr

B) C2H4

C) Cl2

D) CH4

E) All of these samples will have the same average speed at the same temperature.

Matching Questions

Match the following.

A) V1/n1 = V2/n2

B) measures atmospheric pressure

C) measures pressure of a gas in the laboratory

D) PT = PA + PB + PC …

E) V1/T1 = V2/T2

F) measures blood pressure

G) PV = nRT

H) P1V1 = P2V2

1) barometer

Diff: 1 Page Ref: 5.2

2) manometer

Diff: 1 Page Ref: 5.2

3) sphygmomanometer

Diff: 1 Page Ref: 5.2

4) Boyle’s Law

Diff: 1 Page Ref: 5.3

5) Charles’s Law

Diff: 1 Page Ref: 5.3

6) Avogadro’s Law

Diff: 1 Page Ref: 5.3

7) Ideal Gas Law

Diff: 1 Page Ref: 5.4

8) Dalton’s Law

Diff: 1 Page Ref: 5.6

Short Answer Questions

1) Define pressure.

2) Consider a container of gas under a particular P, V, T set of conditions. Describe how the pressure

would change if the volume were doubled while the absolute temperature was increasing by a factor of

two.

3) Why does HOT air rise?

4) Give the major gas in dry air.

5) Why doesn’t Dalton’s Law of Partial Pressures depend on the identity of the gases present?

6) Given the equation C2H6(g) + O2(g) → CO2(g) + H2O(g) (not balanced), determine the number of

liters of CO2 formed at STP when 240.0 grams of C2H6 is burned in excess oxygen gas.

7) Given the equation C2H6(g) + O2(g) → CO2(g) + H2O(g) (not balanced), determine the number of

liters of O2 consumed at STP when 270.0 grams of C2H6 is burned.

8) Explain what the term “mean free path” describes. How does it change with decreasing pressure?

9) Why does the rate of effusion increase with a decrease in the molar mass?

10) Define effusion.