States of Matter - Weebly

12

CHAPTER

SOLUTIONS MANUAL

States of Matter

Section 12.1 Gases

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?

pages 402¨C410

Practice Problems

page 405

1. Calculate the ratio of effusion rates for nitrogen

3. Infer Dive tables are used to determine how

(N2) and neon (Ne).

RateN/RateNe  0.849



molar mass

Rate

20.18

_

 __  ¡Ì_  0.849

¡Ì molar mass 

Rate

28.02

N

Ne

Ne

N

2. Calculate the ratio of diffusion rates for carbon

monoxide and carbon dioxide.

1.25

¡Ì



molar

mass

Rate

_

__



CO

RateCO2

CO2

molar massCO



44.01

_

 1.25

¡Ì

28.01

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?

x

2

3.6 mol/min

Ratex  2.5 mol/min

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 Problems

page 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

Data Analysis Lab

page 408

1. Compare Use the data in the table to make

a graph of atmospheric pressure versus altitude.

Check student graphs

Atmospheric Pressure

v. Altitude

1.0

Atmospheric

Pressure (atm)

Copyright ? Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

2.5 mol/min

Rate



1

__

 ¡Ì_

18 m  2 m  20 m

0.9

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

0.8

0.7

0.6

0.5

0.4

0

600

1200

1800

2400

3000

Altitude (m)

Solutions Manual

Chemistry: Matter and Change ? Chapter 12

237

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 displacement 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.

238

Chemistry: Matter and Change ? Chapter 12

SOLUTIONS MANUAL

Section 12.2 Forces of Attraction

pages 411¨C414

Section 12.2 Assessment

page 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.

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Copyright ? Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

CHAPTER

CHAPTER

12

Section 12.3 Liquids and Solids

pages 415¨C424

Section 12.3 Assessment

page 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.

SOLUTIONS MANUAL

25. Predict which solid is more likely to be

amorphous¡ªone 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.

20. Explain why soap and water are used to clean

clothing instead of water alone.

Section 12.4 Phase Changes

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.

pages 425¨C430

Copyright ? Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

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.

Section 12.4 Assessment

page 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.

The cohesion between mercury atoms is stronger

than the adhesion between mercury and glass.

Solutions Manual

Chemistry: Matter and Change ? Chapter 12

239

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SOLUTIONS MANUAL

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.

pages 434¨C437

Section 12.1

one in which no kinetic energy is lost

32. Explain what the triple point and the critical

35. How does the kinetic energy of particles vary as

point on a phase diagram represents.

a function of temperature?

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

It is directly proportional to their temperature.

36. Use the kinetic-molecular theory to explain the

compression and expansion of gases.

33. Determine the phase of water at 75.00¡ãC and

3.00 atm using Figure 12.29.

Phase Diagram for H2O

Critical point

217.75

Pressure (atm)

Chapter 12 Assessment

Mastering Concepts

34. What is an elastic collision?

The combinations of temperature and pressure

under which a given substance exists as a solid,

liquid, and/or gas.

B

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.

Liquid

Normal

freezing

point

2. The particles are in constant motion and

undergo elastic collisions.

1.00

Solid

Normal

boiling

point

3. The particles have kinetic energy and the

average kinetic energy of the particles is

temperature.

A

Vapor

Triple point

0.00

100.00

38. Describe the common properties of gases.

373.99

Temperature (¡ãC)

liquid

Everyday Chemistry

page 431

Writing in Chemistry

Research to find out more about chocolate and write

a short report. For more information about chocolate,

visit .

240

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.

Chemistry: Matter and Change ? Chapter 12

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.

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Copyright ? Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

CHAPTER

12

CHAPTER

SOLUTIONS MANUAL

40. In Figure 12.31, what happens to the density of

44. Calculate the molar mass of a gas that diffuses

gas particles in the cylinder as the piston moves

from Position A to Position B?

three times faster than oxygen under similar

conditions.

a



Rate

molar mass

_

 __

b

O2

Ratex

¡Ì

x

molar massO2

MM

_1  ¡Ì

_

 3.56 g/mol

x

3

32.00

3.56 g/mol

45. What is the partial pressure of water vapor in an

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?

Copyright ? Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

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?

Ratex

¡Ì

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



Rate

molar mass

_

 __

He

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?

x

0.332 atm; It is about one-third of the 1-atm

pressure at sea level.

molar massHe

MM

_3  ¡Ì

__

 36.0 g/mol

x

1

48. High Altitude The atmospheric pressure in

4.00 g/mol

Denver, Colorado, is usually about 84.0 kPa.

What is this pressure in atm and torr units?

36.0 g/mol

43. What is the ratio of effusion rates of krypton

and neon at the same temperature and pressure?

_  __  ¡Ì_

¡Ì molar mass

Rate

RateKr



molar massNe

Ne

Kr

RateKr/RateNe  0.4931



20.18

 0.4931

83.80

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

Solutions Manual

Chemistry: Matter and Change ? Chapter 12

241

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