States of Matterbehavior of gases. Gases consist of small particles in random motion which experience elastic collisions. 9. Describe how the mass of a gas particle affects its rate

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.SOLUTIONS MANUALCHAPTER 12

States of Matter

Section 12.1 Gasespages 402–410

Practice Problemspage 405

1. Calculate the ratio of effusion rates for nitrogen (N2) and neon (Ne).

RateN/RateNe � 0.849

RateN _ RateNe

� √ ��

molar massNe __ molar massN

� √ ��

20.18 _ 28.02

� 0.849

2. Calculate the ratio of diffusion rates for carbon monoxide and carbon dioxide.

1.25

RateCO _ RateCO2

� √ ��

molar massCO2 __ molar massCO

� √ ��

44.01 _ 28.01

� 1.25

3. Challenge What is the rate of effusion for a gas that has a molar mass twice that of a gas that effuses at a rate of 3.6 mol/min?

2.5 mol/min

Ratex __

3.6 mol/min �

√ � 1 _ 2 Ratex � 2.5 mol/min

Data Analysis Labpage 408

1. Compare Use the data in the table to make a graph of atmospheric pressure versus altitude.

Check student graphs

1200600 1800 2400 3000

cirehpsomt

A)

mta( erusserP

0

0.6

0.7

0.8

0.9

1.0

0.4

0.5

Altitude (m)

Atmospheric Pressurev. Altitude

2. Calculate What is your actual diving depth if your depth gauge reads 18 m, but you are at an altitude of 1800 m and your gauge does not compensate for altitude?

18 m � 2 m � 20 m

3. Infer Dive tables are used to determine how long it is safe for a diver to stay under water at a specific depth. Why is it important to know the correct depth of the dive?

The amount of time that it is safe to stay under water is directly related to the diving depth. If you do not know your actual diving depth, you cannot determine how long it is safe to stay at a particular diving depth.

Practice Problemspage 409

4. What is the partial pressure of hydrogen gas in a mixture of hydrogen and helium if the total pressure is 600 mm Hg and the partial pressure of helium is 439 mm Hg?

161 mm Hg

600 mmHg � 439 mmHg � 161 mmHg

5. Find the total pressure for a mixture that contains four gases with partial pressures of 5.00 kPa, 4.56 kPa, 3.02 kPa, and 1.20 kPa.

5.00 kPa � 4.56 kPa � 3.02 kPa � 1.20 kPa � 13.78 kPa

6. Find the partial pressure of carbon dioxide in a gas mixture with a total pressure of 30.4 kPa if the partial pressures of the other two gases in the mixture are 16.5 kPa and 3.7 kPa.

30.4 kPa � 16.5 kPa � 3.7 kPa � 10.2 kPa

Solutions Manual Chemistry: Matter and Change • Chapter 12 237

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.

238 Chemistry: Matter and Change • Chapter 12 Solutions Manual

SOLUTIONS MANUALCHAPTER 12

7. Challenge Air is a mixture of gases. By percentage, it is roughly 78 percent nitrogen, 21 percent oxygen, and 1 percent argon. (There are trace amounts of many other gases in air.) If the atmospheric pressure is 760 mm Hg, what are the partial pressures of nitrogen, oxygen, and argon in the atmosphere?

760 mm Hg � 0.78 � N2 � 590 mm Hg;

760 mm Hg � 0.21 � O2 � 160 mm Hg;

760 mm Hg � 0.01 � Ar � 8 mm Hg

Section 12.1 Assessment page 410

8. Explain Use the kinetic theory to explain the behavior of gases.

Gases consist of small particles in random motion which experience elastic collisions.

9. Describe how the mass of a gas particle affects its rate of effusion and diffusion.

The rate of effusion and diffusion decreases as mass increases.

10. Explain how gas pressure is measured.

Atmospheric pressure is measured using a barometer. The gas pressure in a closed container is measured using a manometer.

11. Explain why the container of water must be inverted when a gas is collected by displace-ment of water.

If the container is not inverted, the gas, which is less dense than water, will rise through the water and escape from the opening of the container.

12. Calculate Suppose two gases in a container have a total pressure of 1.20 atm. What is the pressure of gas B if the partial pressure of gas A is 0.75 atm?

1.20 atm � 0.75 atm � 0.45 atm

13. Infer whether or not temperature has any effect on the diffusion rate of a gas. Explain your answer.

As temperature increases the velocity of the particles increase and the particles will diffuse faster.

Section 12.2 Forces of Attractionpages 411–414

Section 12.2 Assessmentpage 414

14. Explain what determines a substance’s state at a given temperature.

The intermolecular forces between the particles determine the state of a substance. In a solid, the intermolecular forces are very strong and hold the particles together. In a liquid, the intermolecular forces are weaker and in a gas, the particles no longer experience intermolecular forces.

15. Compare and contrast intermolecular forces and describe intramolecular forces.

Intermolecular forces occur between particles. Intramolecular forces hold particles together.

16. Evaluate Which of the molecules listed below can form hydrogen bonds? For which of the molecules would dispersion forces be the only intermolecular force? Give reasons for your answers

a. H2

b. H2S

c. HCl

d. HF

hydrogen bonds: b, d; only dispersion forces: a; b and d are polar molecules with a highly electronegative atom bonded to hydrogen a is nonpolar

17. Intepret Data In a methane molecule (CH4), there are four single covalent bonds. In an octane molecule (C8H18), there are 25 single covalent bonds. How does the number of bonds affect the dispersion forces in samples of methane and octane? Which compound is a gas at room temperature? Which is a liquid?

More bonds mean more electrons to form temporary dipoles, which means greater dispersion forces. Methane is a gas; octane is a liquid.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



Section 12.3 Liquids and Solidspages 415–424


18. Contrast the arrangement of particles in solids and liquids.

The particles are closer together in solids than in liquids because of intermolecular attractions. Most solids have a regular repeating particle arrangement while liquids have none.

19. Describe the factors that affect viscosity.

Viscosity of a liquid is determined by the type of intermolecular forces in the liquid, the size and shape of the particles, and the temperature.

20. Explain why soap and water are used to clean clothing instead of water alone.

Soaps and detergents decrease the surface tension of water by breaking the hydrogen bonds, which allows the dirt to be carried away by the water.

21. Compare a unit cell and a crystal lattice.

Unit cells are the building blocks of the crystal lattice.

22. Describe the difference between a molecular solid and a covalent network solid.

A molecular solid is formed from molecules held together by intermolecular forces that are weaker than covalent bonds; covalent network solids are formed from molecules held together by covalent bonds.

23. Explain why water forms a meniscus when it is in a graduated cylinder.

Because the adhesive forces between water molecules and the silicon dioxide in glass are greater than the cohesive forces between water molecules, the water rises along the inner walls of the cylinder.

24. Infer why the surface of mercury in a thermometer is convex; that is, the surface is higher at the center.

The cohesion between mercury atoms is stronger than the adhesion between mercury and glass.

25. Predict which solid is more likely to be amorphous—one formed by allowing a molten material to cool slowly to room temperature or one formed by quickly cooling the same material in an ice bath.

The one cooled quickly in an ice bath because amorphous solids often form when molten material cools too quickly for crystals to form.

26. Design an experiment to compare the rela-tive abilities of water and isopropyl alcohol to support skipping stones. Include a prediction about which liquid will be better along with a brief explanation of your prediction.

Make sure students use correct scientific procedures in their experimental designs.

Section 12.4 Phase Changespages 425–430


27. Explain how the addition or removal of energy can cause a phase change.

The addition of energy increases the kinetic energy of the particles, which reduces the intermolecular forces between the particles. As energy is removed, the kinetic energy of the particles decreases and intermolecular forces increase.

28. Explain the difference between the processes of melting and freezing.

Freezing occurs when a liquid becomes a solid and energy is released. Melting requires an input of energy to convert a solid to a liquid.

29. Compare deposition and sublimation.

A substance undergoes deposition when it goes from the vapor phase to the solid phase without going through the liquid phase. A substance undergoes sublimation when it goes from the solid phase directly to the vapor phase without going through the liquid phase. Both occur at the same temperature for a given substance.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



30. Compare and contrast sublimation and evaporation.

In both processes, the substances become a vapor. During sublimation, the substance goes from the solid phase directly to the vapor phase. During evaporation, particles in a liquid gain enough energy to enter the vapor phase. Both occur at the same temperature for a given substance.

31. Describe the information that a phase diagram supplies.

The combinations of temperature and pressure under which a given substance exists as a solid, liquid, and/or gas.

32. Explain what the triple point and the critical point on a phase diagram represents.

Triple point: the temperature at which the three phases of a substance can coexist; critical point: the pressure and temperature above which a substance cannot exist as a liquid

33. Determine the phase of water at 75.00°C and 3.00 atm using Figure 12.29.

Normalfreezingpoint

Normalboilingpoint

Liquid

Critical point

Triple point

A

B

Vapor

Solid

0.00 100.00 373.99

Pres

sure

(atm

)

217.75

1.00

Temperature (°C)

Phase Diagram for H2O

liquid

Everyday Chemistrypage 431

Writing in ChemistryResearch to find out more about chocolate and write a short report. For more information about chocolate, visit glencoe.com.

The reports might contain a variety of information, such as where the beans are grown, how they are processed, or how the final product is distributed and sold.

Chapter 12 Assessmentpages 434–437

Section 12.1

Mastering Concepts 34. What is an elastic collision?

one in which no kinetic energy is lost

35. How does the kinetic energy of particles vary as a function of temperature?

It is directly proportional to their temperature.

36. Use the kinetic-molecular theory to explain the compression and expansion of gases.

Because of the space between gas particles, gases are easily compressed when pushed into a smaller volume. When the pressure is removed, their random motion enables gases to expand.

37. List the three basic assumptions of the kinetic-molecular theory.

1. Matter is composed of small particles.

2. The particles are in constant motion and undergo elastic collisions.

3. The particles have kinetic energy and the average kinetic energy of the particles is temperature.

38. Describe the common properties of gases.

Gases have low density, can be compressed, will expand to fill all available space, and can undergo diffusion and effusion.

39. Compare diffusion and effusion. Explain the relationship between the rates of these processes and the molar mass of a gas.

Both involve the movement of gas particles. Diffusion is the movement of one substance through another; effusion is when a substance under pressure escapes through a tiny opening. Effusion and diffusion rates are inversely related to molecular mass of a gas.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



40. In Figure 12.31, what happens to the density of gas particles in the cylinder as the piston moves from Position A to Position B?

ba

Density decreases because the gas particles occupy more volume per unit mass.

41. Baking at Different Elevations Explain why the baking instructions on a box of cake mix are different for high and low elevations. Would you expect to have a longer or shorter cooking time at a high elevation?

Because of the variation in air pressure with elevation; At high elevations, reduced air pressure results in a lower boiling point for water and cooking time is longer.

Mastering Problems 42. What is the molar mass of a gas that takes three

times longer to effuse than helium?

RateHe _ Ratex

� √ ��

molar massx __ molar massHe

3 _ 1 �

√ ��

MMx __

4.00 g/mol � 36.0 g/mol

36.0 g/mol

43. What is the ratio of effusion rates of krypton and neon at the same temperature and pressure?

RateKr _ RateNe

� √ ��

molar massNe __ molar mass Kr

� √ ��

20.18 _ 83.80

� 0.4931

RateKr/RateNe � 0.4931

44. Calculate the molar mass of a gas that diffuses three times faster than oxygen under similar conditions.

RateO2 _ Ratex

� √ ��

molar massx __ molar massO2

1 _ 3 �

√ ��

MMx _ 32.00

� 3.56 g/mol

3.56 g/mol

45. What is the partial pressure of water vapor in an air sample when the total pressure is 1.00 atm, the partial pressure of nitrogen is 0.79 atm, the partial pressure of oxygen is 0.20 atm, and the partial pressure of all other gases in air is 0.0044 atm?

1.00 atm � 0.79 atm � 0.20 atm � 0.0044 atm � 0.01 atm

46. What is the total gas pressure in a sealed flask that contains oxygen at a partial pressure of 0.41 atm and water vapor at a partial pressure of 0.58 atm?

0.41 atm � 0.58 atm � 0.99 atm

47. Mountain Climbing The pressure atop the world’s highest mountain, Mount Everest, is usually about 33.6 kPa. Convert the pressure to atmospheres. How does the pressure compare with the pressure at sea level?

33.6 kPa � (1 atm/101.325 kPa) � 0.332 atm

0.332 atm; It is about one-third of the 1-atm pressure at sea level.

48. High Altitude The atmospheric pressure in Denver, Colorado, is usually about 84.0 kPa. What is this pressure in atm and torr units?

84.0 kPa � (1 atm/101.325 kPa) � 0.829 atm

84.0 kPa � (760 torr/101.325 kPa) � 6.30 � 102 torr

84.0 kPa � 0.829 atm and 6.30 � 102 torr

49. At an ocean depth of 76.2 m, the pressure is about 8.4 atm. Convert the pressure to mm Hg and kPa units.

8.4 atm � (760 mmHg/1 atm) � 6400 mm Hg

8.4 atm � (101.325 kPa/1 atm) � 850 kPa

8.4 atm � 8.5 � 102 kPa and 6.4 � 103 mm Hg

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



50. Figure 12.32 represents an experimental set-up in which the left bulb is filled with chlorine gas and the right bulb is filled with nitrogen gas. Describe what happens when the stopcock is opened. Assume the temperature of the system is held constant during the experiment.

The gases will diffuse until both bulbs are filled with the same gas mixtures.

Chlorine gas Nitrogen gas

After one hour

Nitrogen and chlorine gas

Nitrogen and chlorine gas

Section 12.2

Mastering Concepts 51. Explain the difference between a temporary

dipole and a permanent dipole.

A temporary dipole forms when one molecule is close to another molecule and the electrons repel each other creating a greater electron density in one part of the molecule. Permanent dipoles are found in polar molecules in which some regions of the molecule are always partially positive and partially negative.

52. Why are dispersion forces weaker than dipole-dipole forces?

Dispersion forces are between temporary dipoles. Dipole-dipole forces are between permanent dipoles.

53. Explain why hydrogen bonds are stronger than most dipole-dipole forces.

A hydrogen bond involves a large difference in electronegativity between the hydrogen atom and the atom it is attached to (O, N, or F), making the bond extremely polar.

54. Compare intramolecular and intermolecular forces.

Intramolecular forces hold atoms together in a molecule while intermolecular forces hold different molecules together.

55. Hypothesize why long, nonpolar molecules would interact more strongly with one another than spher-ical nonpolar molecules of similar composition.

Because long molecules have greater surface areas, more intermolecular forces can exist.

Mastering Problems 56. Polar Molecules Use relative differences in

electronegativity to label the ends of the polar molecules listed as partially positive or partially negative.

a. HF

H��F�

b. HBr

N��O�

c. NO

H��Br�

b. CO

C��O�

57. Draw the structure of the dipole-dipole interaction between two molecules of carbon monoxide.

��

��

See Figure 13.8. The drawing should show two CO molecules, with the C partially positive and the O partially negative. The C of each molecule should be bonded to the O of the other.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



58. Decide which of the substances listed can form hydrogen bonds.

a. H2Ob. H2O2c. HFd. NH3

All of the substances can form hydrogen bonds.

59. Decide which one of the molecules listed below can form intermolecular hydrogen bonds, and then draw it, showing several molecules attached together by hydrogen bonds.

a. NaClb. MgCl2c. H2O2d. CO2

c H2O2 can form intermolecular hydrogen bonds.

O — O

H

H

—

—

H

—

H

—

H

O — O

O — O

—

H

—

Hydrogenbond

Section 12.3

Mastering Concepts 60. What is surface tension, and what conditions

must exist for it to occur?

The energy needed to increase the surface area of a liquid by a given amount; strong intermolecular forces exist between the liquid particles

61. Explain why the surface of water in a graduated cylinder is curved.

Adhesion between water and glass is greater than cohesion between water molecules.

62. Which liquid is more viscous at room tempera-ture, water or molasses? Explain.

Molasses; stronger intermolecular forces keep molasses from flowing.

63. Explain how two different forces play a role in capillary action.

Capillary action results from the opposing forces of adhesion and cohesion. Adhesive forces between water molecules and molecules in the glass of a capillary tube are stronger than the cohesive forces holding water molecules together, so water moves up the walls of the capillary tube.

64. Use the drawings in Figure 12.33 to compare the cubic, monoclinic, and hexagonal crystal systems.

Hexagonal

a = b ≠ cα = β = 90°, γ = 120°

c

ba

βα

γ

Monoclinic

a ≠ b ≠ cα = γ = 90° ≠ β

c

ba

βα

γ

Cubic

a = b = cα = β = γ = 90°

c

ba

α

γ

β

In the cubic crystal system, all of the sides are an equal length and the angles are all 90°. In the monoclinic crystal system, a, b, and c are unequal in length and � and � are 90° angles, but is not. In the hexagonal crystal system, a and b are equal in length, but c is not. The angles � and are equal to 90°, but � is equal to 120°.

65. What is the difference between a network solid and an ionic solid?

Network solid is held together by covalent bonds; ionic solid by electrostatic attraction.

66. Explain why most metals bend when struck but most ionic solids shatter.

The sea of electrons that holds metal ions together can easily move to accommodate outside forces; in ionic solids a strong force can separate the solid along the plane bonding groups of atoms together.

67. List the types of crystalline solids that are usually good conductors of heat and electricity.

metallic solids; ionic solids when molten or dissolved in an aqueous solution

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.


SOLUTIONS MANUALCHAPTER

12

68. How does the strength of a liquid’s intermo-lecular forces affect its viscosity?

Stronger intermolecular forces result in higher viscosity because the forces hold the particles together too tightly for them to flow easily.

69. Explain why water has a higher surface tension than benzene, whose molecules are nonpolar.

Surface tension increases with strength of intermolecular forces. Water molecules are held together by strong hydrogen bonds, resulting in higher surface tension; the weaker dispersion forces between benzene molecules result in lower surface tension.

70. Compare the number of particles in one unit cell for each of the following types of unit cells.

a. simple cubic

8

b. body-centered cubic

9

71. Predict which solid is more likely to be amorphous – one formed by cooling a molten material over 4 hours at room temperature or one formed by cooling a molten material quickly in an ice bath.

The one cooled quickly in an ice bath because amorphous solids often form when molten material cools too quickly for crystals to form.

72. Conductivity Predict which solid will conduct electricity better—sugar or salt.

Salt, because it contains ions while sugar is a molecular solid without any ions.

73. Explain why ice floats in water but solid benzene sinks in liquid benzene. Which behavior is more “normal”?

Surface tension increases with strength of intermolecular forces. Water molecules are held together by strong hydrogen bonds, resulting in higher surface tension; the weaker dispersion forces between benzene molecules result in lower surface tension. Benzene is more “normal”.

Mastering Problems 74. Given edge lengths and face angles, predict the

shape of each of the following crystals.

a. a � 3nm, b � 3 nm, c � 3nm and � � 90°, �°� 90 and � � 90°

cubic

b. a � 4nm, b � 3 nm, c � 5nm and � � 90°, �° � 100 and � � 90°

monoclinic

c. a � 3nm, b � 3 nm, c � 5nm and � � 90°, �°� 90 and �� 90°

tetragonal

d. a � 3nm, b � 3 nm, c � 5nm and � � 90°, �° � 90 and � � 120°

hexagonal

Section 12.4

Mastering Concepts 75. How does sublimation differ from deposition?

Sublimation occurs when a solid is converted to a gas; deposition occurs when a gas is converted to a solid.

76. Compare boiling and evaporation.

Evaporation: conversion of a liquid to a gas at the liquid’s surface; boiling: when vapor pressure is equal to external atmospheric pressure; it occurs at and below the surface where bubbles form.

77. Define the term melting point.

the temperature at which the crystal lattice of a solid disintegrates and it becomes a liquid

78. Explain the relationships among vapor pressure, atmospheric pressure, and boiling point.

Boiling point is the temperature at which vapor pressure exerted by liquid molecules escaping from the surface of a sample equals the atmospheric pressure on the surface of the liquid.

79. Explain why dew forms on cool mornings.

When water vapor in the air comes in contact with a cool object such as a windshield, it condenses on the object.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



80. Why does a pile of snow slowly shrink even on days when the temperature never rises above the freezing point of water?

Some of the snow sublimes.

81. Phase Diagrams Copy and label the solid, liquid, and gas phases, triple point, and critical point on Figure 12.34.

-80 -60 -40 0 +20 +40-20

Pres

sure

(atm

)

16

12

8

4

0

Temperature (°C)

Phase Diagram

-100

Triple point

Gas

LiquidSolid Critical point is not shown

82. Why does it take more energy to boil 10 g of liquid water than to melt an equivalent mass of ice?

Melting does not require as much energy because the particles in a solid do not have to move far apart or gain much movement to form a liquid. Gas particles are much further apart and move much more rapidly than liquid particles.

Mixed Review 83. Use the kinetic-molecular theory to explain why

both gases and liquids are fluids.

Because the particles in gases and liquids are held together by fewer attractive forces than in solids, allowing them to flow

84. Use intermolecular forces to explain why oxygen is a gas at room temperature and water is a liquid.

Oxygen molecules are nonpolar and held together by dispersion forces, making them easy to separate. Water molecules are held together by stronger hydrogen bonds, making them harder to separate. As a result, water has a higher boiling point.

85. Use the kinetic-molecular theory to explain why gases are easier to compress than liquids or solids.

Because particles in gases are farther apart than particles in liquids or solids, there is more space for the particles to be compressed.

86. At 25ºC and a pressure of 760 mm Hg, the density of mercury is 13.5 g/mL; water at the same temperature and pressure has a density of 1.00 g/mL. Explain this difference in terms of intermolecular forces and the kinetic-molecular theory.

Metallic bonds holding mercury atoms together are stronger than hydrogen bonds holding water molecules together, so the mercury atoms are more closely packed, resulting in greater mass per unit volume.

87. If two identical containers each hold the same gas at the same temperature but the pressure inside one container is exactly twice that of the other container, what must be true about the amount of gas inside each container?

The container with twice the pressure has twice the number of particles.

88. List three types of intermolecular forces.

hydrogen bonding, dispersion forces, dipole-dipole forces

89. When solid sugar crystals are dissolved in a glass of water, they form a clear homogeneous solution in which the crystals are not visible. If the beaker is left out at room temperature for a few days, the crystals reappear in the bottom and on the sides of the glass. Is this an example of freezing?

No. The only phase change that occurred is liquid water evaporating to form water vapor. The sugar was always in the solid phase, even when not visible. The crystals became large enough to see with the unaided eye over time.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



12

Think Critically 90. Interpret Graphs Examine Figure 12.35,

which plots vapor pressure versus temperature for water and ethanol.

-20-40 0 20 60 80 10040

Vapo

r pr

essu

re (t

orr) 800

760

600

400

200

0

Temperature (°C)

Ethanol

Water

Vapor Pressure v. Temperature

a. What is the boiling point of water at 1 atm?

100°C

b. What is the boiling point of ethanol at 1 atm?

78.5°C

c. Estimate the temperature at which water will boil when the atmospheric pressure is 0.80 atm.

94°C

91. Hypothesize What type of crystalline solid do you predict would best suit the following needs?

a. a material that can be melted and reformed at a low temperature

molecular solid

b. a material that can be drawn into long, thin wires

metallic solid

c. a material that conducts electricity when molten

ionic solid

d. an extremely hard material that is nonconductive

covalent network solid

92. Compare and Contrast An air compressor uses energy to squeeze air particles together. When the air is released, it expands, allowing the energy to be used for purposes such as gently cleaning surfaces without using a more abrasive liquid or solid. Hydraulic systems essentially work the same way, but they involve compression of liquids rather than air. What do you think are some advantages and disadvan-tages of these two types of technology?

Air compressors produce rapid outputs of a large amount of energy because gases can be greatly compressed. Hydraulic systems involve liquid water, which cannot be compressed as much, and are more useful for a slow, steady output of energy.

93. Graph Use Table 12.6 to construct a phase diagram for ammonia.

Selected Points

Pressure(atm)

Temperature(˚C)

Triple point 0.060 –77.7

Critical point 112 132.2

Normal boiling point

1.0 –33.5

Normal freezing point

1.0 –77.7

Phase Diagrams for Ammonia

–50–100 0 50 100 100 150

Pres

sure

(atm

)

0

–20

0

20

40

60

100

80

120

Temperature (°C)

Phase Diagram for Ammonia

Liquid

Critical point

Solid

Freezingpoint

Boiling point

Gas

Triple point

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



94. Apply A solid being heated stays at a constant temperature until it is completely melted. What happens to the heat energy put into the system during that time?

The energy is used to break the intermolecular forces holding the particles of the solid together.

95. Communicate Which process—effusion or diffusion—is responsible for your being able to smell perfume from an open bottle that is located across the room from you? Explain.

diffusion; gas particles in the perfume are mixing with air particles

96. Infer A laboratory demonstration involves pouring bromine vapors, which are a deep red color, into a flask of air and then tightly sealing the top of the flask. The bromine is observed to first sink to the bottom of the beaker. After several hours have passed, the red color is distributed equally throughout the flask.

a. Is bromine gas more or less dense than air?

more dense

b. Would liquid bromine diffuse more or less quickly than gaseous bromine after you pour it into another liquid?

less quickly

97. Analyze Use your knowledge of intermolecular forces to predict whether ammonia (NH3) or methane (CH4) will be more soluble in water.

Ammonia will be more soluble in water than methane becuase ammonia and water can form relatively strong intermolecular attractions (hydrogen bonds) between them. Methane (a nonpolar molecule) and water will form only intermolecular dispersive forces which are weaker than hydrogen bonds.

98. Evaluate List three PHASE changes that require energy and three that release energy.

requires energy—melting, sublimation, vaporization; releases energy—freezing, deposition, condensation

99. Evaluate Supercrital carbon dioxide is a liquid form of CO2 used in the food industry to decaffeinate tea, coffee, and colas, as well as in the pharmaceutical industry to form polymer microparticles used in drug delivery systems. Use Figure 12.36 to determine what conditions must be used to form supercritical carbon dioxide.

-56.6 31.1

Pres

sure

(bar

)

73

5

Temperature (ºC)

Phase Diagram for CO2

Supercriticalfluid

a pressure above 73 bars and a temperature above 31.1°C

Challenge Problem 100. You have a solution containing 135.2 g of

dissolved KBr in 2.3 L of water.

What volume of this solution, in mL, would you use to make 1.5 L of a 0.1 mol/L KBr solution?

Molar mass of KBr 0 119.00 g � 1 mol

135.2 g KBr

__ 2.3L water

� 1 mol KBr __ 119.00 gKBr

� 0.49 mol/L KBr/water

0.49 mol _ L V stock � 0.1 mol _

L 31.5 L

V stock � 0.3 L � 300 mL

Cumulative Review 101. Identify each of the following as an element,

a compound, a homogeneous mixture, or heterogeneous mixture. (Chapter 3)

a. air

homogeneous mixture

b. blood

heterogeneous mixture

c. antimony

element

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



12

d. ammonia

compound

e. mustard

heterogeneous mixture

f. water

compound

102. You are given two clear, colorless aqueous solutions. You are told that one solution contains an ionic compound and one contains a covalent compound. How could you determine which is an ionic solution and which is a covalent solutions? (Chapter 9)

They could be tested for conductivity. The ionic compound in solution should conduct electricity; the covalent compound should not.

103. Which branch of chemistry would most likely study matter and phase changes? (Chapter 1)

a. biochemistryb. organic chemistryc. physical chemistryd. polymer chemistry

c

104. What type of reaction is the following? (Chapter 9)

K2CO3(aq) � BaCl2(aq) 0 2KCl(aq) � BaCO3(s)

a. combustionb. double-replacementc. single-replacmentd. synthesis

b

105. Which chemist produced the first widely used and accepted periodic table? (Chapter 6)

a. Dimitri Mendeleevb. Henry Moseleyc. John Newlandsd. Lothar Meyer

a

Additional Assessment

Writing in Chemistry 106. Musk is the basic ingredient of many

perfumes, soaps, shampoos, and even foods like chocolates, licorice, and hard candies. Both synthetic and natural musk molecules have high molar masses compared to other perfume ingredients, and as a result, have a slower rate of diffusion assuring a slow, sustained release of fragrance. Write a report on the chemistry of perfume ingredients, emphasizing the importance of diffusion rate as a property of perfume.

Student reports should point out that a slow diffusion rate results in a longer lasting fragrance.

107. Birthstones Find out what your birthstone is and write a brief report about the chemistry of that gem. Find out its chemical composition, which category its unit cell is in, how hard and durable it is, and its approximate cost at present.

Check student reports for accuracy.

108. Propane gas is a commonly used heating fuel for gas grills and homes. However, it is not packaged as a gas. It is liquefied and referred to as liquid propane or “LP gas.” Make a poster explaining the advantages and disadvantages of storing and transporting propane as a liquid rather than a gas.

A liquid requires a smaller container than a gas and the container can hold more fuel as a liquid rather than a solid.

109. Other States of Matter Research and prepare an oral report about one of the following topics: plasma, superfluids, fermi-onic condensate, or Bose-Einstein condensate. Share your report with your classmates and prepare a visual aid that can be used to explain your topic.

Check student reports.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



Document-Based Questions 110. Why does solid iodine sublime readily? Use

your knowledge of intermolecular forces to explain.

The dispersion forces that hold iodine molecules together in its solid crystal are relatively weak so when those bonds break, the atoms can move

apart directly from the solid to the gas state.

111. Why is liquid iodine not usually visible if crystals are heated in the open air?

Iodine melts at 112.9°C, boils at 183.0°C, and its vapor pressure is 100 mm Hg at 116.5°C. When being heated rapidly or in a closed vessel solid iodine will melt. A vapor pressure of about 100 mm Hg must be attained to allow liquid iodine to form and prevent sublimation. In containers open to the air, the crystals will usually sublime completely before melting.

112. Why is it necessary to use a sealed ampoule in this investigation?

If the ampoule were not sealed, the iodine vapor would escape into the room.

113. Infer why the iodine solidifies when the tube is tilted.

The iodine cools quickly as it is tilted.

Standardized Test Practice pages 438–439

1. What is the ratio of effusion rates for nitric oxide (NO) and nitrogen tetroxide ( N2 O4 )?

a. 0.326b. 0.571c. 1.751d. 3.066

c

Rat e NO _ Rate N204

� √ ��

molar mas s N204

__ molar mas s NO

� √ ��

92.01 _ 30.01

� 1.751

2. Which is NOT an assumption of the kinetic-molecular theory?

a. Collisions between gas particles are elastic.b. All the gas particles in a sample have the

same velocity.c. A gas particle is not significantly attracted

or repelled by other gas particles.d. All gases at a given temperature have the

same average kinetic energy.

b

3. A sealed flask contains neon, argon, and krypton gas. If the total pressure in the flask is 3.782 atm, the partial pressure of Ne is 0.435 atm, and the partial pressure of Kr is 1.613 atm, what is the partial pressure of Ar?

a. 2.048 atmb. 1.734 atmc. 1556 atmd. 1318 atm

b

3.782 � 0.435 � 1.613 atm � 1.734 atm

Use the figure below to answer Question 4.

4. Hydrogen and nitrogen react as shown to form ammonia (N H3 ). What will be true of this reaction?

3 nitrogen molecules(6 nitrogen atoms)

3 hydrogen molecules(6 hydrogen atoms)

+

a. Three ammonia molecules will be formed, with zero molecules left over.

b. Two ammonia molecules will be formed, with two hydrogen molecules left over.

c. Six ammonia molecules will be formed, with zero molecules left over.

d. Two ammonia molecules will be formed, with two nitrogen molecules left over.

d

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



12

5. Which does not affect the viscosity of a liquid?

a. intermolecular attractive forcesb. size and shape of moleculesc. temperature of the liquidd. capillary action

d

Use the graph below to answer Questions 6–8.

2000 40000

Pres

sure

(atm

)

106

105

104

103

102

101

100

Temperature (ºC)

6000

Phase Diagram for Carbon

Diamond

Graphite

Liquid

Vapor

6. Under what conditions is diamond most likely to form?

a. temperatures > 5000 K and pressures < 100 atm

b. temperatures > 6000 K and pressures > 25 atm

c. temperatures < 3500 K and pressures > 105 atm

d. temperatures < 4500 K and pressures < 10 atm

c

7. Find the point on the graph at which carbon exists in three phases: solid graphite, solid diamond, and liquid carbon. What are the temperature and pressure at that point?

a. 4700 K and 106 atmb. 3000 K and 103 atmc. 5100 K and 105 atmd. 3500 K and 80 atm

d

8. In what form or forms does carbon exist at 6000 K and 105 atm?

a. diamond onlyb. liquid carbon onlyc. diamond and liquid carbond. liquid carbon and graphite

b

Use the table below to answer Questions 9–10.

Properties of Single Bonds

BondStrength (kJ/mol) Length (pm)

H—H 435 74

Br—Br 192 228

C—C 347 154

C—H 393 104

C—N 305 147

C—O 356 143

CI—CI 243 199

I —I 151 267

S—S 259 208

9. Create a graph to show how bond length varies with bond strength. Place bond strength on the x-axis.

Relationship between bond length and strength

0

50

100

150

200

250

300

0 50 100 150 200 250 300 350 400 450 500

Bond strength, kJ/mol

Bo

nd

len

gth

, p

m

10. Summarize the relationship between bond strength and bond length.

As the bond strength increases, the bond length decreases.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



Use the table below to answer Question 11.

Geometry of AlCl3 and PCl3Compound AlCl3 PCl3

Molecular Shape

11. What are the names of the shapes of the mole-cules for each compound? Explain how the atomic arrangements in each compound result in their different shapes despite their similar formulas.

AlCl3 has a trigonal planar shape, while PCl3 has trigonal pyramidal shape. The difference in their shapes is due to the number of unpaired electron pairs. Because aluminum has three valence electrons, when it bonds to chlorine, all of those electrons are used in bonding and no unpaired electrons are left, therefore giving it a planar shape. PCl3 has a pyramidal shape because its five valence electrons are not all used in bonding to three chlorine atoms, leaving one pair of electrons, which repel the bonding electrons to make a three-dimensional shape.

12. Potassium chromate and lead(II) acetate are both dissolved in a beaker of water, where they react to form solid lead(II) chromate. What is the balanced net ionic equation describing this reaction?

a. Pb2�(aq) � C2H3O2−(aq) 0 Pb(C2H3O2)2(s)

b. Pb2�(aq) � 2CrO4− (aq) 0 Pb(CrO4)2(s)

c. Pb2�(aq) � CrO42− (aq) 0 PbCrO4(s)

d. Pb�(aq) � C2H3O2−(aq) 0 PbC2H3O2(s)

e. Pb2�(aq) � CrO4− (aq) 0 PbCrO5(s)

c

13. The solid phase of a compound has a definite shape and volume because its particles

a. are not in constant motion.b. are always more tightly packed in the liquid

phase.c. can vibrate only around fixed points.d. are held together by strong intramolecular

forces.e. have no intermolecular forces.

c

Use the table below to answer Questions 14 and 15.

Properties of Sulfuric Acid

Formula H2SO4

Molar mass 98.08 g/mol

Density 1.834 g/mL

14. What is the mass of 75.0 mL of sulfuric acid?

a. 40.9 gb. 138 gc. 98.08 gd. 180 ge. 198.4 g

b

75.0 mL � (1.834 g/1 mL) � 138 g

15. How many atoms of oxygen are present in 2.4 mol of sulfuric acid?

a. 940 atomsb. 230 atomsc. 1.5 � 1 0 24 atomsd. 5.8 � 1 0 24 atomse. 6.02 � 1 0 23 atoms

d

2.4 mol H2SO4 � 6.02 � 1023 molecules ___ 1 mol H2SO4

� 4 atoms O __ 1 molecule

� 5.8 � 1024 atoms

Documents

States of Matterbehavior of gases. Gases consist of small particles in random motion which experience elastic collisions. 9. Describe how the mass of a gas particle affects its rate