CHAPTER 14 Study Guide - colonial.net

CHAPTER CHAPTER

14 StudyGuide 14 Study Guide

Study Tip Key Concepts • The combined gas law allows you to do
Color Code Variables Suggest that calculations for situations in which only
students practice solving numeric 14.1 Properties of Gases the amount of gas is constant.
problems by assigning a different color • Gases are easily compressed because of the
to each variable when they write the 14.3 Ideal Gases
mathematical expression they will use space between particles in a gas. • To calculate the number of moles of a
to solve the problem. Students should
continue using the assigned colors as • The amount of gas (n), volume (V ), and contained gas requires an expression that
they rearrange the expression to solve temperature (T ) are factors that affect gas contains the variable n.
for the unknown and as they substitute pressure (P).
values for the variables. • Real gases differ most from an ideal gas at
14.2 The Gas Laws low temperatures and high pressures.
If your class subscribes to the Inter- • As the pressure of a gas increases, the
active Textbook with ChemASAP, 14.4 Gases: Mixtures and Movements
your students can go online to volume decreases, if the temperature is • In a mixture of gases, the total pressure is the
access an interactive version of the constant.
Student Edition and a self-test. sum of the partial pressures of the gases.
• As the temperature of an enclosed gas • Gases of lower molar mass diffuse and effuse
with ChemASAP increases, the volume increases, if the
pressure is constant. faster than gases of higher molar mass.

• As the temperature of an enclosed gas
increases, the pressure increases, if the
volume is constant.

Vocabulary

• Boyle’s law (p. 418) • Dalton’s law of partial • Graham’s law of effusion
• Charles’s law (p. 420) pressures (p. 432) (p. 435)
• combined gas law (p. 424)
• compressibility (p. 413) • diffusion (p. 435) • ideal gas constant (p. 426)

• effusion (p. 435) • ideal gas law (p. 426)

• Gay-Lussac’s law (p. 422) • partial pressure (p. 432)

Key Equations

• Boyle’s law: P1 ϫ V1 ϭ P2 ϫ V2 • Ideal gas law: P ϫ V ϭ n ϫ R ϫ T or PV ϭ NRT
• Dalton’s law: Ptotal ϭ P1 ϩ P2 ϩ P3 ϩ…
• Charles’s law: V1 ϭ V2
T1 T2
RateA molar massB
• Gay-Lussac’s law: P1 P2 • Graham’s law: RateB ϭ B molar massA
T1 T2
ϭ

• Combined gas law: P1 ϫ V1 ϭ P2 ϫ V2
T1 T2

Organizing Information

Use these terms to construct a concept Boyle’s law Charles’s law partial pressure
map that organizes the major ideas of
this chapter.

combined gas law diffusion

Concept Map 14 Solve the
Concept Map with the help of
an interactive guided tutorial.

with ChemASAP

438 Chapter 14

Chapter Resources Technology

Print • Computer Test Bank, Chapter 14 Test
• Core Teaching Resources, Chapter 14 • Interactive Textbook with ChemASAP,
Practice Problems, Vocabulary Review, Quiz, Chapter 14
Chapter Test A, Chapter Test B • Virtual Chem Labs, 15–19

438 Chapter 14

CHAPTER CHAPTER

14 Assessment 14 Assessment

Reviewing Content 39. The space between particles is
reduced.
14.1 Properties of Gases 49. A gas with a volume of 3.00 ϫ 102 mL at 150.0°C
is heated until its volume is 6.00 ϫ 102 mL. What 40. The increased kinetic energy of the
39. What happens to the particles in a gas when the is the new temperature of the gas if the pressure particles causes collisions to occur
gas is compressed? remains constant during the heating process? more frequently and with more
force.
40. Explain why heating a contained gas that is held 50. Write the mathematical expression for the
at a constant volume increases its pressure. combined gas law. 41. The volume decreases.The mol–
ecules have less kinetic energy and
41. Describe what happens to the volume of a bal- 51. A sealed cylinder of gas contains nitrogen gas cause less pressure on the inside of
loon when it is taken outside on a cold winter at 1.00 ϫ 103 kPa pressure and a temperature the balloon.
day. Explain why the observed change happens. of 20°C. When the cylinder is left in the sun, the
temperature of the gas increases to 50°C. What 42. The pressure doubles.
42. A metal cylinder contains 1 mol of nitrogen gas. is the new pressure in the cylinder? 43. The pressure quadruples.
What will happen to the pressure if another mole 44. As particles are removed from the
of gas is added to the cylinder, but the tempera- 52. Show how Gay-Lussac’s law can be derived from
ture and volume do not change? the combined gas law. container, there is a decrease in
the number of collisions.
43. If a gas is compressed from 4 L to 1 L and the 14.3 Ideal Gases 45. V1/T1 = V2/T2
temperature remains constant, what happens to V1 and V2 are the initial and final
the pressure? 53. Describe an ideal gas. volumes; T1 and T2 are the initial
and final temperatures.
44. Use the drawing to help explain why gas pressure 54. Explain why it is impossible for an ideal gas 46. 1.00 × 102 kPa
decreases when gas is removed from a container to exist. 47. 1.80 L
with a fixed volume. 48. 18 L
55. What is the volume occupied by 1.24 mol of a 49. 846 K (573°C)
200 kPa Decreasing Pressure gas at 35°C if the pressure is 96.2 kPa? 50. (P1V1)/T1 = (P2V2)/T2
51. 1.10 × 103 kPa
14.2 The Gas Laws 56. What volume will 12.0 g of oxygen gas (O2) 52. When the volume is constant,
occupy at 25°C and a pressure of 52.7 kPa? V1 = V2, so the volume terms
45. Write the mathematical equation for Charles’s cancel, leaving the equation for
law and explain the symbols. 57. If 4.50 g of methane gas (CH4) is in a 2.00-L Gay-Lussac’s law.
container at 35°C, what is the pressure in 53. Its particles have no volume, there
46. The gas in a closed container has a pressure of the container? are no attractions between them,
3.00 ϫ 102 kPa at 30°C (303 K). What will the and collisions are elastic. An ideal
pressure be if the temperature is lowered to 58. A helium-filled weather balloon has a volume gas follows the gas laws at all
Ϫ172°C (101 K)? of 2.4 ϫ 102 L at 99 kPa pressure and a tempera- temperatures and pressures.
ture of 0°C. What is the mass of the helium in 54. Particles in a real gas have a finite
47. Calculate the volume of a gas (in L) at a pressure the balloon? volume and are attracted to one
of 1.00 ϫ 102 kPa if its volume at 1.20 ϫ 102 kPa is another at low temperatures and
1.50 ϫ 103 mL. 14.4 Gases: Mixtures and Movements high pressures.
55. 33.0 L
48. A gas with a volume of 4.0 L at 90.0 kPa expands 59. In your own words, state Dalton’s law of 56. 17.6 L
until the pressure drops to 20.0 kPa. What is its partial pressure. 57. 3.60 × 102 kPa
new volume if the temperature doesn’t change? 58. 42 g
60. Which gas effuses faster: hydrogen or chlorine? 59. The total pressure of a gaseous
How much faster? mixture is equal to the sum of the
individual pressures of each gas.
61. Which gas effuses faster at the same tempera- 60. Hydrogen gas diffuses faster than
ture: molecular oxygen or atomic argon? chlorine gas by an approximate
factor of six.
62. Calculate the ratio of the velocity of helium 61. molecular oxygen
atoms to the velocity of neon atoms at the 62. 2.25:1
same temperature. 63. 3.08:1

63. Calculate the ratio of the velocity of helium The Behavior of Gases 439
atoms to the velocity of fluorine molecules at
the same temperature.

Assessment 439

CHAPTER Assessment CHAPTER

14 continued 14 Assessment continued

64. Gases are easily compressed Understanding Concepts 71. The ratio of two variables is always a constant.
because there is a lot of space What can you conclude about the relationship
between the particles. 64. How does kinetic theory explain the compress- between the two variables?
ibility of gases?
65. Boiling the water fills the can with 72. A 3.50-L gas sample at 20°C and a pressure of
steam. When the can is plunged Use this description to answer Questions 65 and 66. 86.7 kPa expands to a volume of 8.00 L. The final
upside down into ice water the A teacher adds 1 mL of water to an empty metal pressure of the gas is 56.7 kPa. What is the final
steam is trapped and rapidly soda can. The teacher heats the can over a temperature of the gas, in degrees Celsius?
condenses, reducing gas pressure burner until the water boils and then quickly
inside the can.The walls of the can plunges the can upside down in an ice-water 73. Explain the reasons why real gases deviate from
are not strong enough to with- bath. The can immediately collapses inward as ideal behavior.
stand the comparatively high though crushed in a trash compactor.
atmospheric pressure, which 74. How would the number of particles of two gases
crushes the can. 65. Use kinetic theory to explain why the can compare if their partial pressures in a container
collapsed inward. were identical?
66. The results would be much less dra-
matic.The change in volume (and 66. If the experiment were done with a dry can, 75. Why does a balloon filled with helium deflate
in internal pressure) from heated air would the results be similar? Explain. more quickly than a balloon filled with air?
to cold air is much less dramatic
than when steam (a vapor) con- 67. Why do aerosol containers display the warning, 76. A certain gas effuses four times as fast as oxygen
denses to water (a liquid). “Do not incinerate”? (O2). What is the molar mass of the gas?

67. High temperatures increase the 77. During an effusion experiment, a certain num-
pressure of the contents of the ber of moles of an unknown gas passed through
container and may cause it to a tiny hole in 75 seconds. Under the same condi-
explode. tions, the same number of moles of oxygen gas
passed through the hole in 30 seconds. What is
68. The pressure will double. the molar mass of the unknown gas?
69. Temperatures measured on the
78. The photograph shows a tube with cotton balls
Kelvin scale are directly propor- at each end. The cotton ball at the left was
tional to the average kinetic soaked with hydrochloric acid. The cotton ball
energy of the particles. Celsius on the right was soaked with a solution of
temperatures are not. ammonia. When these compounds react, they
70. The water boils at a higher form a white solid, ammonium chloride. Based
temperature, which speeds the on the location of the ammonium chloride in the
cooking process. tube, which gas diffuses at a faster rate, hydrogen
71. The variables are directly chloride or ammonia? Explain.
proportional.
72. 165°C 68. The manufacturer of an aerosol deodorant
73. The particles in a real gas have a packaged in a 150-mL container plans to pro-
finite volume and are attracted to duce a container of the same size that will hold
one another. twice as much gas. How will the pressure of the
74. The number of particles would gas in the new product compare with that of the
be equal. gas in the original container?
75. Helium atoms have a smaller molar
mass than oxygen and nitrogen 69. Why must Kelvin temperatures be used in
molecules and effuse faster calculations that involve gases?
through pores in the balloon.
76. 2.0 g 70. Explain how using a pressure cooker reduces the
77. 2.0 × 102 g time required to cook food.

440 Chapter 14

78. Ammonia diffuses faster than hydrogen
chloride. Based on the location of the reac-
tion product, the ammonia molecules
travel about twice the distance of the
hydrogen chloride molecules, in the same
time.

440 Chapter 14

Critical Thinking Concept Challenge 79. A vacuum contains no matter to
allow the transfer of kinetic energy
79. How does the vacuum in the flask used to store 85. Oxygen is produced in the laboratory by heating between molecules.
liquid nitrogen prevent heat transfer? potassium nitrate (KNO3). The data table below
gives the volume of oxygen produced at STP 80. The gases that make up the atmos-
80. Gases will diffuse from a region of higher con- from different quantities of KNO3. Use the data phere, just like any other form of
centration to a region of lower concentration. to determine the mole ratio by which KNO3 and matter, are held near Earth by the
Why don’t the gases in Earth’s atmosphere O2 react. force of gravity.
escape into the near-vacuum of space?
Mass of KNO3 (g) Volume of O2 (cL) 81. Helium gas is composed of small
81. What real gas comes closest to having the char- 0.84 9.3 atoms with little attraction for
acteristics of an ideal gas? Explain your answer. 1.36 15.1 each other.
2.77 30.7
82. Death Valley in California is at 86 m below sea 4.82 53.5 82. The partial pressure of oxygen
level. Will the partial pressure of oxygen in Death 6.96 77.3 would be greater than at sea level,
Valley be the same, lower, or higher than the because the atmospheric pressure
partial pressure of oxygen at sea level? Give a 86. A mixture of ethyne gas (C2H2) and methane would be greater than at sea level.
reason for your answer. gas (CH4) occupied a certain volume at a total
pressure of 16.8 kPa. When the sample burned, 83. a. 1.63 × 102 kPa
83. The following reaction takes place in a sealed the products were CO2 gas and H2O vapor. The b. 4.48 × 102 kPa
40.0-L container at a temperature of 120°C. CO2 was collected and its pressure found to be
25.2 kPa in the same volume and at the same 84. There could be different amounts
4NH3(g) ϩ 5O2(g) ¡ 4NO(g ) ϩ 6H2O(g) temperature as the original mixture. What per- of each gas or the gases could be
centage of the original mixture was methane? at different pressures.
a. When 34.0 g of NH3 reacts with 96.0 g of O2,
what is the partial pressure of NO in the 87. A 0.10-L container holds 3.0 ϫ 1020 molecules of 85. 2 mol KNO2 for each 1 mol O2
sealed container? H2 at 100 kPa and 0°C.
a. If the volume of a hydrogen molecule is 86. 4a6. 2%.0C×H140−3%
b. What is the total pressure in the container? 6.7 ϫ 10Ϫ24 mL, what percentage of the vol- 87.
ume of the gas is occupied by its molecules?
84. The graph shows the direct relationship between b. If the pressure is increased to 100,000 kPa, the b. 2.0%
volume and temperature for three different gas volume of the gas is 1 ϫ 10Ϫ4 L. What fraction
samples. Offer at least one explanation for why of the total volume do the hydrogen mol- 88. Because attractions between mol-
the graphs are not identical for the three sam- ecules now occupy?
ples. (Hint: What variables other than tempera- ecules in gases such as nitrogen
ture and volume can be used to describe a gas?) 88. Many gases that have small molecules, such as
N2 and O2, have the expected molar volume of and oxygen are insignificant, these
Volume vs. Temperature 22.41 L at STP. However, other gases behave in a
Data for Three Gases very non-ideal manner, even if extreme pres- gases have the molar volume of an
sures and temperatures are not involved. The
6Volume (L) molar volumes of CH4, CO2, and NH3 at STP are ideal gas, 22.4 L at STP. Based on
Gas A 22.37 L, 22.26 L, and 22.06 L, respectively.
Explain the reasons for these large departures their molar volumes at STP, there
5 from the ideal.
are attractions between mol-
4 Gas B
ecules of CH4, CO2, and NH3.These
3 attractions increase in strength
Gas C
from methane to carbon dioxide
2
to ammonia.
1

0
؊300 ؊200 ؊100 0 100 200 300

Temperature (؇C)

Assessment 441

The Behavior of Gases 441

CHAPTER Assessment CHAPTER

14 continued 14 Assessment continued

89. K = °C + 273 Cumulative Review 99. What is the significance of the volume 22.4 L?
90. 10.6 g/cm3 (Chapter 10)
89. What is the mathematical relationship between
91. 82 protons, 82 electrons, the Kelvin and Celsius temperature scales? 100. Calculate the molecular formula of each of the
(Chapter 3) following compounds. (Chapter 10)
124 neutrons a. The empirical formula is C2H4O and the
90. A metal sample has a mass of 9.92 g and molar mass is 88 g.
92. nickel, Ni measures 4.5 cm ϫ 1.3 cm ϫ 1.6 mm. What is the b. The empirical formula is CH and the molar
density of the metal? (Chapter 3) mass is 104 g.
93. a. tungsten c. The molar mass is 90 g. The percent compo-
91. How many electrons, protons, and neutrons are sition is 26.7% C, 71.1% O, and 2.2% H.
94. c. selenium there in an atom of lead-206? (Chapter 4)
101. What type of reaction are each of the following?
95. b. SO2 92. Which element has the following electron (Chapter 11)
96. a. tin(II) bromide configuration? (Chapter 5) a. Calcium reacts with water to form calcium
hydroxide and hydrogen gas.
b. barium sulfate 1s 2s 2p 3s 3p 4s 3d b. Mercury and oxygen are prepared by heating
mercury(II) oxide.
c. magnesium hydroxide 93. Which of these elements are metals? (Chapter 6)
102. Write a balanced equation for each chemical
d. iodine pentafluoride a. arsenic b. tungsten c. xenon reaction. (Chapter 12)
a. Tetraphosphorus decoxide reacts with water
97. 206 g 94. Which element is most likely to form a com- to form phosphoric acid.
b. Aluminum hydroxide and hydrogen sulfide
98. a. 158 g pound with strontium? (Chapter 7) form when aluminum sulfide reacts with
water.
b. 98 g a. neon b. tin c. selenium
103. Calculate the percent composition of
c. 342 g 95. Which compound contains at least one double 2-propanol (C3H7OH). (Chapter 12)

d. 331 g bond? (Chapter 8) 104. Aluminum oxide is formed from its elements.
(Chapter 12)
99. It is the volume occupied by a. H2Se b. SO2 c. PCl3
Al(s) ϩ O2(g) ¡ Al2O3(s)
1 mol of a gas at STP. 96. Name each compound. (Chapter 9)
a. Balance the equation.
100. a. C4H8O2 a. SnBr2 b. BaSO4 b. How many grams of each reactant are
b. C8H8 c. Mg(OH)2 d. IF5
c. C3H6O3 needed to form 583 g Al2O3(s)?
97. An atom of lead has a mass 17.16 times greater 105. Explain why a gas expands until it takes the
101. a. single-replacement
than the mass of an atom of carbon-12. What is shape and volume of its container. (Chapter 13)
b. decomposition
102. a. P4O10 + 6H2O → 4H3PO4 the molar mass of this isotope of lead? 106. Use the drawings to explain how gas pressure is
produced. (Chapter 13)
b. Al2S3 + 6H2O → (Chapter 10)
2Al(OH)3 + 3H2S Container
98. Calculate the molar mass of each substance. wall
103. 60.0% C, 13.3% H, 26.7% O
104. a. 4Al + 3O2 → 2Al2O3 (Chapter 10)

b. 3.09 × 102 g Al; 2.75 × 102 g O2 a. Ca(CH3CO2)2
105. The motion of particles in a gas is b. H3PO4
c. C12H22O11
constant, random, and rapid. d. Pb(NO3)2

106. Gas pressure is the result of the

collisions of gas particles with

the container wall.

442 Chapter 14

442 Chapter 14

Standardized Test Prep Standardized Test Prep

Test-Taking Tip Use the graphs to answer Questions 7–10. A graph 1. b
may be used once, more than once, or not at all. 2. c
Constructing a Diagram You may be asked to 3. c
draw a diagram or make changes to an existing Graph A Graph B 4. a
drawing. Sketch lightly at first so you can erase 6 6 5. b
easily if you need to, or do a sketch on a separate 5 5 6. b
piece of paper. Once you are sure of your answer, 4 4 7. A
draw the final diagram. 3 3 8. B
2 2 9. C
Select the choice that best answers each question or 1 1 10. A and B
completes each statement. 11. There will be four green spheres
0 123456 0 123456
and four red spheres in each bulb.
1. A gas in a balloon at constant pressure has a Graph C 12. Each bulb will contain two blue,
6
volume of 120.0 mL at Ϫ123°C. What is its vol- 5 three green, and four red spheres.
4
ume at 27.0°C? 3
2
a. 60.0 mL b. 240.0 mL 1

c. 26.5 mL d. 546 mL 0 123456

2. If the Kelvin temperature of a gas is tripled and Which graph shows each of the following?
the volume is doubled, the new pressure will be 7. directly proportional relationship
a. 1/6 the original pressure. 8. graph with slope ϭ 0
b. 2/3 the original pressure. 9. inversely proportional relationship
c. 3/2 the original pressure.
d. 5 times the original pressure. 10. graph with a constant slope

3. Which of these gases effuses fastest?

a. Cl2 b. NO2 c. NH3 d. N2

4. All the oxygen gas from a 10.0-L container at

a pressure of 202 kPa is added to a 20.0-L

container of hydrogen at a pressure of 505 kPa. Use the drawing to answer Questions 11 and 12.

After the transfer, what are the partial pressures

of oxygen and hydrogen?

a. Oxygen is 101 kPa; hydrogen is 505 kPa.

b. Oxygen is 202 kPa; hydrogen is 505 kPa.

c. Oxygen is 101 kPa; hydrogen is 253 kPa.

d. Oxygen is 202 kPa; hydrogen is 253 kPa.

5. Which of the following changes would increase a. b. c.
the pressure of a gas in a closed container?
I. Part of the gas is removed. 11. Bulb A and bulb C contain different gases.
II. The container size is decreased. Bulb B contains no gas. If the valves between
III. Temperature is increased. the bulbs are opened, how will the particles
a. I and II only of gas be distributed when the system reaches
b. II and III only equilibrium? Assume none of the particles
c. I and III only are in the tubes that connect the bulbs.
d. I, II, and III
12. Make a three-bulb drawing with 6 blue spheres
6. A real gas behaves most nearly like an ideal gas in bulb A, 9 green spheres in bulb B, and 12 red
a. at high pressure and low temperature. spheres in bulb C. Then draw the setup to repre-
b. at low pressure and high temperature. sent the distribution of gases after the valves are
c. at low pressure and low temperature. opened and the system reaches equilibrium.
d. at high pressure and high temperature.
Standardized Test Prep 443

The Behavior of Gases 443