chapters 17–20 resources - wikispaces · pdf fileteacher guide and answers ... chemical...

Chapters 17–20 Resources

i-vi CMC_Printer PDF.indd ii-vi CMC_Printer PDF.indd i 3/15/07 12:10:25 PM3/15/07 12:10:25 PM

Copyright © by The McGraw-Hill Companies, Inc. All rights reserved. Permission is granted to reproduce the material contained herein on the condition that such materials be reproduced only for classroom use; be provided to students, teachers, and families without charge; and be used solely in conjunction with the Glencoe Chemistry: Matter and Change program. Any other reproduction, for sale or other use, is expressly prohibited.

Send all inquiries to:Glencoe/McGraw-Hill8787 Orion PlaceColumbus, OH 43240-4027

ISBN: 978-0-07-878764-5MHID: 0-07-878764-5

Printed in the United States of America.

1 2 3 4 5 6 7 8 9 10 045 11 10 09 08 07

i_vi_CMC_FF_878764.indd iii_vi_CMC_FF_878764.indd ii 3/27/07 5:04:44 PM3/27/07 5:04:44 PMPrinter PDF

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.

To the Teacher . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

Chapters 17-20 Resources

Reproducible Student Pages

Student Lab Safety Form . . . . . . . . . . . . . . . . . . . . . . . . . . vi

Chapter 17

Chemical Equilibrium . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Chapter 18

Acids and Bases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Chapter 19

Redox Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Chapter 20

Electrochemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Teacher Guide and Answers

Chapter 17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

Chapter 18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

Chapter 19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

Chapter 20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

Table ofContents

iii

i-vi CMC_Printer PDF.indd iiii-vi CMC_Printer PDF.indd iii 3/15/07 12:10:53 PM3/15/07 12:10:53 PM

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.

Lab Safety Form

vi

Name:

Date:

Lab type (circle one) : Launch Lab MiniLab ChemLab

Lab Title:

Read carefully the entire lab and then answer the following questions. Your teacher must initial this form before you begin the lab.

1. What is the purpose of the investigation?

2. Will you be working with a partner or on a team?

3. Is this a design-your-own procedure? Circle: Yes No

4. Describe the safety procedures and additional warnings that you must follow as you perform this investigation.

5. Are there any steps in the procedure or lab safety symbols that you do not understand? Explain.

Teacher Approval Initials

Date of Approval

i_vi_CMC_FF_878764.indd vii_vi_CMC_FF_878764.indd vi 4/6/07 7:14:19 PM4/6/07 7:14:19 PMPrinter PDF

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.

Chapter 17 Chemical EquilibriumMiniLab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

ChemLab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Teaching Transparency Masters and Worksheets . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Maths Skills Transparency Masters and Worksheets . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Study Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Chapter Assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

STP Recording Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Table ofContents

1

Reproducible Pages

001_CMC_FF_878764.indd 1001_CMC_FF_878764.indd 1 4/4/07 3:49:39 PM4/4/07 3:49:39 PMPrinter PDF

Name Date Class

2 Chemistry: Matter and Change • Chapter 17 ChemLab and MiniLab Worksheets

mini LAB 17Observe Shifts in Equilibrium

Observing and Inferring Le Châtelier’s principle states that if a stress is placed on areaction at equilibrium, the system will shift in a way that will relieve the stress. In thisexperiment, you will witness an equilibrium shift in a colorful way.

Materials test tubes (2); 10-mL graduated cylinder; 250-mL beaker; concentrated hydro-chloric acid; 0.1M CoCl2 solution; ice bath; table salt; hot plate; nonmercury thermometer

Procedures1. Read and complete the lab safety form.

2. Place about 2 mL of 0.1M CoCl2 solution in a test tube. Record the color of the solution.

3. Add about 3 mL of concentrated HCl to the test tube. Record the color of the solution. CAUTION: HCl can burn skin and clothing.

4. Add enough water to the test tube to make a color change occur. Record the color.

5. Add about 2 mL of 0.1M CoCl2 to another test tube. Add concentrated HCl dropwiseuntil the solution turns purple. If the solution becomes blue, add water until it turnspurple.

6. Place the test tube in an ice bath that has had some salt sprinkled into the ice water.Record the color of the solution in the test tube.

7. Place the test tube in a hot water bath that is at least 70°C. Record the color of thesolution.

Analysis

1. Interpret Use the equation for the reaction you just observed to explain your obser-vations of color in steps 2–4. The equation is as follows.

Co(H2O)62� � 4Cl� 3 CoCl4

2� � 6H2O

pink blue

2. Describe how the equilibrium shifts when energy is added or removed.

3. Interpret From your observations of color in steps 6 and 7, determine whether thereaction is exothermic or endothermic. C

opyr

ight

©G

lenc

oe/M

cGra

w-H

ill, a

div

isio

n of

The

McG

raw

-Hill

Com

pani

es, I

nc.

001_026 CMC_FF_878764.qxd 04/06/2007 06:57 PM Page 2 Printer PDF

Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

ChemLab and MiniLab Worksheets Chemistry: Matter and Change • Chapter 17 3

CHEMLAB 17

Safety Precautions• Always wear safety goggles, gloves, and a lab apron. • Silver nitrate is highly toxic and will stain skin and clothing.• Sodium sulfide is a skin irritant and should be kept away from acids.

ProblemHow can a saturated solu-tion of one ionic compoundreact with another ioniccompound to form anotherprecipitate? What is therelationship between solu-bility and the Ksp value of asaturated solution?

MaterialsAgNO3 solutionNaCl solutionNa2S solution24-well microplatethin-stem

pipettes (3)

Compare Two SolubilityProduct ConstantsLe Châtelier’s principle is a powerful tool for explaining how a

reaction at equilibrium shifts when a stress is placed on the sys-tem. In this experiment, you can use Le Châtelier’s principle to evaluate the relative solubilities of two precipitates. By observing theformation of two precipitates in the same system, you can infer therelationship between the solubilities of the two ionic compounds andthe numerical values of their solubility product constants (Ksp). Youwill be able to verify your own experimental results by calculatingthe molar solubilities of the two compounds using the Ksp for each compound.

Pre-Lab

1. Read the entire CHEMLAB.

2. Prepare all written materials that you will takeinto the laboratory. Be sure to include safety precautions and procedure notes. Use the datatable on the next page.

3. State Le Châtelier’s principle.

4. Identify the control and the independent variablein the experiment.

5. When a solid dissolves to form two ions and thesolid’s Ksp is known, what is the mathematicalformula you can use to calculate the molar solubility?

Objectives• Observe evidence that a precipitate is in equilib-

rium with its ions in solution.• Infer the relative solubilities of two sparingly sol-

uble ionic compounds.• Compare the values of the Ksp for two different

compounds and relate them to your observations.• Explain your observations of the two precipitates

by using Le Châtelier’s principle.• Calculate the molar solubilities of the two ionic

compounds from their Ksp values.

001-026 CMC Printer PDF 3/1/07 4:13 PM Page 3

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Procedure

1. Read and complete the lab safety form.

2. Place 10 drops of AgNO3 solution in well A1 of a24-well microplate. Place 10 drops of the samesolution in well A2.

3. Add 10 drops of NaCl solution to well A1 and 10 drops to well A2.

4. Allow the precipitate to form in each well.Record your observations.

5. To well A2, add 10 drops of Na2S solution.

6. Allow the precipitate to form. Record your observations of the precipitate.

7. Compare the contents of wells A1 and A2 andrecord your observations in the data table.

8. Use a wash bottle to transfer the contents of thewell plate into a waste beaker.

CHEMLAB 17

Analyze and Conclude

1. Analyze Write the complete equation for the reaction that occurred when you mixed NaCland AgNO3 in Step 3. Write the net ionic equation.

2. Analyze Write the solubility product constant expression for the equilibrium establishedin wells A1 and A2 in Step 3. Ksp (AgCl) � 1.8 � 10�10.

3. Analyze Write the equation for the equilibrium that was established in well A2 when youadded Na2S. Ksp (Ag2S) � 8 � 10�48.

4. Identify the two precipitates by color.

5. Compare the Ksp values for the two precipitates. Which of the two ionic compounds ismore soluble?

Observations

Step 3

Step 5

Step 6

Precipitate Formation

001_026 CMC_FF_878764.qxd 03/17/2007 05:37 PM Page 4Printer PDF

Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


6. Recognize Cause and Effect Use Le Châtelier’s principle to explain how the additionof Na2S in Step 5 affected the equilibrium established in well A2.

7. Calculate the molar solubilities of the two precipitates using the Ksp values. Which ofthe precipitates is more soluble?

8. Identify What evidence from this experiment supports your answer to Question 7?Explain.

9. Compare your observations of the well plate from the side with yourobservations from the top. What did you notice?

10. Research how industries use precipitation to remove hazardous chemicals from waste-water.

Inquiry Extension

Soluble v. Insoluble The reactants that you used in this ChemLab are all soluble ionic compounds, andthe precipitates are insoluble. How does soluble Na2S differ from insoluble Ag2S? How does soluble NaCldiffer from insoluble AgCl? Use this information, Ksp data from Table 17.3, and other reference sources todevelop general rules for solubility.

Error Analysis

CHEMLAB 17


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

6 Chemistry: Matter and Change • Chapter 17 Teaching Transparency Masters

Chemical EquilibriumChemical Equilibrium

TEACHING TRANSPARENCY MASTER

Use with Chapter 17,Section 17.1

50

A 4NH3(g) � 5O2(g) 3 4NO(g) � 6H2O(g)

B 2NO2(g) 3 N2O4(g)

C N2(g) � 3H2(g) 3 2NH3(g)

D Ag�(aq) � 2NH3(aq) 3 Ag(NH3)2�(aq)

E 2NO(g) � 2H2(g) 3 N2(g) � 2H2O(g)

F COCl2(g) 3 CO(g) � Cl2(g)

G HCN(aq) � H2O(l) 3 H3O�(aq) � CN�(aq)

H H2O(g) � CO(g) 3 H2(g) � CO2(g)


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Teaching Transparency Worksheets Chemistry: Matter and Change • Chapter 17 7

1. Write the equilibrium constant expressions for the reactions on the transparency.

A E

B F

C G

D H

2. What is heterogeneous equilibrium?

3. Which equilibrium reactions are homogeneous equilibriums?

4. Which equilibrium reaction is a heterogeneous equilibrium?

5. When writing equilibrium constant expressions, pure solids and liquids are not included.Why? Why do you include all reactants of equation D in its equilibrium constant expression?

6. If the Keq for one of the reactions was 35.6, what would you know about the equilibrium?


TEACHING TRANSPARENCY WORKSHEET


50


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


1

2

3

4

CO(g) � 3H2(g) 3 CH4(g) � H2O(g)

CO(g) � 3H2(g) CH4(g) � H2O(g)

CO(g)

CO(g) � 3H2(g) CH4(g) � H2O(g)

CO(g) � 3H2(g) CH4(g) � H2O(g)

CO(g) � 3H2(g) CH4(g) � H2O(g)

H2O(g)

How Changing ConcentrationAffects EquilibriumHow Changing ConcentrationAffects Equilibrium



51


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


1. Why do the changes shown in equations 1 and 2 cause the equilibrium to move to theright? What other changes in concentration would also cause a shift to the right?

2. Why do the changes shown in equations 3 and 4 cause the equilibrium to move to theleft? What other changes in concentration would also cause a shift to the left?

3. What effect would decreasing the volume of the reaction container have on the equilibrium? Why?

4. When does changing the volume of the reaction container not affect the equilibrium?

5. The production of methane and water vapor from carbon monoxide and hydrogen gas is anexothermic reaction. What does this tell you about how an increase in temperature wouldaffect the equilibrium of this reaction? How would it affect the equilibrium constant?

6. When does changing the temperature not affect a reaction at equilibrium?

How Changing ConcentrationAffects EquilibriumHow Changing ConcentrationAffects Equilibrium



51


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

10 Chemistry: Matter and Change • Chapter 17 Math Skills Transparency Masters

Determining EquilibriumDetermining Equilibrium

MATH SKILLS TRANSPARENCY MASTER


28

Rea

ctio

nC

on

cen

trat

ion

sEq

uili

bri

um

C

on

stan

t (K

eq)

1.

2CH

4(g

) 3

C2H

2(g

) �

3H2(

g)

[CH

4] �

0.50

0M0.

153

[C2H

2] �

0.19

4M[H

2] �

0.58

2M

2.

HC

ON

H2(

g) 3

NH

3(g

) �

CO

(g)

[HC

ON

H2]

�1.

9 �

10�

2 M4.

8[N

H3]

�0.

30M

[CO

] �

0.30

M

3.

PCl 5

(g) 3

PCl 3

(g)

�C

l 2(g

)[P

Cl 5

] �

0.30

M1.

8[P

Cl 3

] �

0.45

M[C

l 2]

�0.

22M

4.

N2O

4(g

) 3

2NO

2(g

)[N

2O4]

�0.

754M

4.16

�10

�3

[NO

2] �

5.60

�10

�2 M

5.

H2(

g)

�l 2

(g) 3

2HI(

g)

[H2]

�0.

110M

50.2

[l2]

�0.

500M

[Hl]

�0.

780M


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Math Skills Transparency Worksheets Chemistry: Matter and Change • Chapter 17 11

The equilibrium constants for the reactions in the table are correct at a certain tempera-ture. The concentrations given in the table, however, may or may not be correct whenthe system is at equilibrium at that temperature. Use the information in the table toanswer the following questions.

1. On the basis of the Keq values given in the table, which reaction mixture contains thelargest amount of product(s) when at equilibrium? Explain.

2. Which reaction mixture contains the largest amount of reactants when at equilibrium?Explain.

3. Which reactions in the table have concentrations that represent the systems at equilibrium? Explain.

4. For each reaction that is not at equilibrium, change the concentration of only one of thereactants or products so that the ratio represents the system at equilibrium.

Determining EquilibriumDetermining Equilibrium

MATH SKILLS TRANSPARENCY WORKSHEET


28


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Using Solubility Product ConstantsUsing Solubility Product Constants



29

Solubility Product Constants at 298 K

Compound Ksp Compound Ksp Compound Ksp

Carbonates Halides Hydroxides

BaCO3 2.6 � 10�9 CaF2 3.5 � 10�11 Al(OH) 4.6 � 10�33

CaCO3 3.4 � 10�9 PbBr2 6.6 � 10�6 Ca(OH)2 5.0 � 10�6

CuCO3 2.5 � 10�10 PbCl2 1.7 � 10�5 Cu(OH)2 2.2 � 10�20

PbCO3 7.4 � 10�14 PbF2 3.3 � 10�8 Fe(OH)2 4.9 � 10�17

MgCO3 6.8 � 10�6 PbI2 9.8 � 10�9 Fe(OH)3 2.8 � 10�39

Ag2CO3 8.5 � 10�12 AgCl 1.8 � 10�10 Mg(OH)2 5.6 � 10�12

ZnCO3 1.5 � 10�10 AgBr 5.4 � 10�13 Zn(OH)2 3 � 10�17

Hg2CO3 3.6 � 10�17 AgI 8.5 � 10�17 Sulfates

Chromates Phosphates BaSO4 1.1 � 10�10

BaCrO4 1.2 � 10�10 AlPO4 9.8 � 10�21 CaSO4 4.9 � 10�5

PbCrO4 2.3 � 10�13 Ca3(PO4)2 2.1 � 10�33 PbSO4 2.5 � 10�8

Ag2CrO4 1.1 � 10�12 Mg3(PO4)2 1.0 � 10�24 Ag2SO4 1.2 � 10�5


Name Date Class

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 list of solubility product constants (Ksp) to answer the following questions. Avoiddoing detailed calculations. Try to estimate the answers as much as possible and providea short justification for your reasoning.

1. Write the solubility product constant expression for each of the following salts.

a. PbI2 b. Ag3PO4

2. What is the solubility of PbSO4 in water at 298 K?

3. What is the approximate concentration of fluorine in a CaF2 solution?

4. A chemist finds that 4.6 � 10�5 moles of Ag2SO4 dissolves in a liter of a certain solvent.Is the solvent water or AgNO3 solution? Explain.

5. Will a precipitate form if a 0.075M MgCl2 solution is added to an equal amount of a0.25M NaOH solution? Explain.

Using Solubility Product ConstantsUsing Solubility Product Constants



29


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

14 Chemistry: Matter and Change • Chapter 17 Study Guide


Section 17.1 Equilibrium: A State of Dynamic Balance In your textbook, read about chemical equilibrium.

Complete each statement.

1. When a reaction results in almost complete conversion of reactants to products, chemists

say the reaction goes to .

2. A reaction that can occur in both the forward and the reverse directions is called a(n)

.

3. is a state in which the forward and reverse reactions balance

each other because they take place at equal rates.

4. At equilibrium, the concentrations of reactants and products are ,

but that does not mean that the amounts or concentrations are .

5. Equilibrium is a state of , not one of .

In your textbook, read about equilibrium expressions and constants.

For each statement below, write true or false.

6. The law of chemical equilibrium states that at a given pressure, a chemicalsystem may reach a state in which a particular ratio of reactant to productconcentrations has a constant value.

7. The equation H2(g) � I2(g) 3 2HI(g) is an example of a homogeneousequilibrium.

8. If an equilibrium constant has a value less than one, the reactants arefavored at equilibrium.

9. The value for Keq is constant only at a specific volume.

10. If the equilibrium constant for a reaction at 300 K is 49.7, theconcentration of the reactants will be greater than the concentration of the products.

11. A heterogeneous equilibrium means that reactants and products arepresent in more than one state.

12. The product of the forward chemical reaction is HI, for the equilibriumexpression:

Keq �[HI]2�[H2][I2]

STUDY GUIDECHAPTER 17


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Study Guide Chemistry: Matter and Change • Chapter 17 15

In your textbook, read about determining equilibrium constants.

A chemist did two experiments to determine the equilibrium constant for the reaction ofsulfur dioxide with oxygen to form sulfur trioxide. Use the table showing the results ofthe experiments to answer the following questions.

13. Write the equation to calculate the equilibrium constant for the reaction.

14. Is this reaction an example of a homogeneous or heterogeneous equilibrium?

15. Calculate the equilibrium constant from the data obtained in experiment 1.

16. What is the equilibrium constant for the reaction in experiment 2?

17. Was it necessary to calculate both equilibrium constants? Why or why not?

18. What does this experiment show about the initial concentrations of products and reac-tants in a reversible reaction?

Section 17.1 continued


2SO2(g) � O2(g) 3 2SO3(g) at 873 K

Experiment 1 Experiment 2

Initial concentrations Equilibrium concentrations Initial concentrations Equilibrium concentration

[SO2] � 2.00M [SO2] � 1.50M [SO2] � 0.500M [SO2] � 0.590M

[O2] � 1.50M [O2] � 1.26M [O2] � 0M [O2] � 0.0450M

[SO3] � 3.00M [SO3] � 3.50M [SO3] � 0.350M [SO3] � 0.260M


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Section 17.2 Factors Affecting Chemical EquilibriumIn your textbook, read about Le Châtelier’s Principle.

Answer the following questions.

1. What does Le Châtelier’s Principle say?

2. What are three kinds of stresses that can be placed on a system?

For each reaction below, state the direction, left or right, in which the equilibrium willshift when the indicated substance is added. Identify one other way in which the reactioncould be shifted in the same direction you indicated. (Hint: There may be more than oneway to do this.)

3. Reaction: N2(g) � 3H2(g) 3 2NH3(g); NH3 added

4. Reaction: H2(g) � I2(g) 3 2HI(g); H2 added

5. Reaction: CO(g) � H2O 3 CO2(g) � H2(g); H2O added

6. Reaction: 2SO2(g) � O2(g) 3 2SO3(g); SO3 added

7. Reaction: 2SO2(g) � O2(g) 3 2SO3(g); SO2 added

8. Reaction: 2NCl3(g) 3 N2(g) � 3Cl2(g); NCl3 added



Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


In your textbook, read about factors affecting chemical equilibrium.

Use each of the terms below just once to complete the passage.

When you decrease the volume of a reaction vessel, you (9)

the pressure. This causes a reaction at equilibrium to shift to the side with the

(10) number of moles. If the reaction has an equal number of

moles of reactants and products, changing the volume of the reaction vessel causes no

(11) in the equilibrium.

Changing the temperature of a reaction at equilibrium alters both the equilibrium

(12) and the equilibrium position. When a reaction is

(13) , which means it releases energy, lowering the temperature

shifts the equilibrium to the (14) because the forward reaction

liberates heat and removes the (15) .

A (16) speeds up a reaction by lowering the

(17) requirements for the reaction, but it does so equally in both the

(18) and the (19) directions. The reaction

will reach equilibrium more quickly, but with no change in the amount of product formed.

For each reaction below, indicate in which direction the equilibrium shifts when thestated stress is applied to the system. Write R if the reaction shifts to the right, L if itshifts to the left, or NC if there is no change.

Reaction Stress

20. PCl5(g) 3 PCl3(g) � Cl2(g) � heat temperature increase

21. CO(g) � Fe3O4(s) 3 CO2(g) � 3FeO(s) volume increase

22. C2H2(g) � H2O(g) 3 CH3CHO(g) � heat temperature decrease

23. 2NO(g) � H2(g) 3 N2O(g) � H2O(g) � heat volume decrease

24. Heat � H2(g) � I2(g) 3 2HI(g) temperature decrease

25. H2(g) � Cl2(g) 3 2HCl(g) � heat volume decrease



right exothermic increase stress catalyst energy

smallest change reverse constant forward


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Section 17.3 Using Equilibrium ConstantsIn your textbook, read about calculating equilibrium concentrations.


1. What can you use the equilibrium constant to do?

2. Given the reaction: N2 � O2 3 2NO for which the Keq at 2273 K is 1.2 � 10�4

a. Write the equilibrium constant expression for the reaction.

b. Write the equation that would allow you solve for the concentration of NO.

c. What is the concentration of NO if [N2] � 0.166M and [O2] � 0.145M?

3. What is the solubility product constant?

4. What is the solubility product constant expression for the reaction:Mg3(PO4)2(s) 3 3Mg2�(aq) � 2PO4

3�(aq)

5. Given the equilibrium BaSO4(s) 3 Ba2�(aq) � SO42�(aq), what is the solubility

product constant expression?

6. The solubility product constant for BaSO4 at 298 K is 1.1 � 10�10. Calculate the solubility of BaSO4 in mol/L at 298 K.



Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


In your textbook, read about predicting precipitates.

The solubility product constant can be used to determine if a precipitate will form whentwo aqueous solutions are mixed together. First, calculate the concentrations of the ionsin the final solution. Use the solubility product constant expression to calculate the ionproduct (Qsp ) for the substance that might precipitate. Compare the result with the Kspof the substance.

7. What can you say about a solution when

a. Qsp is greater than Ksp?

b. Qsp is equal to Ksp?

c. Qsp is less than Ksp?

8. Predict whether a precipitate of AgBr will form if 100 mL of 0.0025M AgNO3 and 100 mL of 0.0020M NaBr are mixed.

9. Explain briefly why Ag3PO4 might be more soluble in water than in the same volume ofa solution containing Na3PO4.




Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.

Student Recording Sheet

26 Chemistry: Matter and Change • Chapter 17

Name Date Class

Standardized Test PracticeMultiple Choice

Select the best answer from the choices given, and fill in the corresponding circle.

1. 4. 7.

2. 5. 8.

3. 6. 9.

Short Answer

Answer each question with complete sentences.

10.

11.

12.

Extended Response


13.

14.

15.

SAT Subject Test:Chemistry

16. 17. 18.

CHAPTER 17

Assessment

026_027_CMC_FF_878764.indd Sec1:26026_027_CMC_FF_878764.indd Sec1:26 4/6/07 7:15:39 PM4/6/07 7:15:39 PMPrinter PDF

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.

Chapter 18 Acids and BasesMiniLab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

ChemLab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29


Maths Skills Transparency Masters and Worksheets . . . . . . . . . . . . . . . . . . . . . . . . . 40

Study Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Chapter Assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50


Table ofContents

27

Reproducible Pages


Name Date Class


mini LAB 18Compare Acid Strengths

Observing and Inferring How can you determine the relative strengthsof acid solutions?

Materials glacial acetic acid; distilled water; 10-mL graduated cylinder;dropping pipette; 50-mL beaker; 24-well microplate; conductivity tester withbattery; stirring rod

Procedure 1. Read and complete the lab safety form.

2. Use a 10-mL graduated cylinder to measure 3 mL of glacial acetic acid.Use a dropping pipette to transfer the acid into Well A1 of a 24-wellmicroplate.

3. Lower the electrodes of a conductivity tester into Well A1. Record yourresults. WARNING: Glacial acetic acid is corrosive and toxic by inhalation.Handle with caution.

4. Rinse the graduated cylinder and pipette with water. Measure 3 mL of6.0M acetic acid, and transfer it to Well A2 of the microplate. Test andrecord the conductivity of the solution.

5. Repeat Step 4 with 1.0M acetic acid and 0.10M acetic acid using wells A3and A4, respectively.

Analysis

1. Write the equation for the ionization of acetic acid in water and the equilibrium con-stant expression. (Keq � 1.8 � 10�5) What does the size of Keq indicate about thedegree of ionization of acetic acid?

2. Explain whether the following approximate percent ionizations fit your laboratoryresults: glacial acetic acid, 0.1%; 6.0M acetic acid, 0.2%; 1.0M acetic acid, 0.4%; 0.1Macetic acid, 1.3%.

3. State a hypothesis that will explain your observations and incorporate your answer toQuestion 2.

4. Utilize your hypothesis to draw a conclusion about the need to use large amounts ofwater for rinsing when acid spills on living tissue.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.


Name Date Class


CHEMLAB 18

Safety Precautions• Always wear safety goggles and a lab apron.• WARNING: Dissolving NaOH in water generates heat. Phenolphthalein

is flammable. Keep away from flames.

ProblemHow can you determinethe molar concentration ofa base solution? How doyou know when the neu-tralization reaction hasreached the equivalencepoint?

Objectives• Recognize the color

change of the indicatorthat shows that theequivalence point hasbeen reached.

• Measure the mass of theacid and the volume ofthe base solution used.

• Calculate the molar con-centration of the basesolution.

Materials50-mL buretteburette clampring standsodium hydroxide

pellets (NaOH)potassium hydro-

gen phthalate (KHC8H4O4)

distilled waterweighing bottlespatula

250-mL Erlenmeyerflask

500-mL Florence flask and rubber stopper

250-mL beakercentigram balancewash bottlephenolphthalein

solution

Standardize a BaseThe procedure called titration can be used to standardize a solu-

tion of a base, which means determine its molar concentration.To standardize a base, a solution of the base with unknown molarityis gradually added to a solution containing a known mass of an acid.The procedure enables you to determine when the number of molesof added OH� ions from the base equals the number of moles of H� ion from the acid.

Pre-Lab

1. What is the equivalence point of a titration?


3. What is the independent variable? The dependentvariable? Constant?

4. When the solid acid dissolves to form ions, howmany moles of H� ions are produced for everymole of acid used?

5. What is the formula used to calculate molarity?

6. Prepare a data table that will accommodate multi-ple titration trials.

7. List safety precautions that must be taken.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Procedure


2. Place about 4 g of NaOH in a 500-mL Florenceflask. Add enough water to dissolve the pelletsand bring the volume of the NaOH solution toabout 400 mL. Stopper the flask.

3. Use the weighing bottle to mass by differenceabout 0.40 g of potassium hydrogen phthalate(KHC8H4O4, molar mass � 204.32 g/mol) intoa 250-mL Erlenmeyer flask. Record this mass.

4. Use a wash bottle to rinse the insides of theflask, and add about 50 mL of water. Add twodrops of phenolphthalein indicator solution.

5. Rinse the buret with 10 mL of your base solu-tion. Discard the rinse solution in a discardbeaker. Attach the buret to the ring stand usingthe buret clamp.

6. Fill the buret with NaOH solution. The level ofthe liquid should be at or below the zero mark.To remove any air trapped in the tip of theburet, allow a small amount of the base to flowfrom the tip into the discard beaker. Read theburet to the nearest 0.02 mL, and record thisinitial reading.

7. Place a piece of white paper on the base of thering stand. Swirl the flask while allowing theNaOH solution to flow slowly from the buretinto the flask.

8. When the pink color begins to persist longer asthe flask is swirled, add the base drop-by-drop.

9. The end point is reached when one additionaldrop of base turns the acid pink. The pink colorshould persist as the flask is swirled. Record thefinal volume in the buret.

10. Calculate the molarity of your base using Steps 1–4 in the Analyze and Conclude section.

11. Refill the buret. Rinse the flask with water.Repeat the titration until the calculated valuesof the molarity for three trials show close agreement.

12. Cleanup and Disposal Wash the neutralizedsolutions down the sink with plenty of water.

CHEMLAB 18

Trial 1

mass of weighing bottle and acid

mass of weighing bottle

mass of solid acid

moles of acid

moles of base required

final reading of base burette

initial reading of base burette

volume of base used in mL

molarity of base

Titration Data


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.



1. Interpret Data For each tritation, calculate the number of moles of acid used by dividingthe mass of the sample by the molar mass of the acid.

2. Infer How many moles of base are required to react with the moles of acid you used?

3. Calculate Convert the volume of base to liters.

4. Calculate the molarity of the base by dividing the moles of base by the volume of base in liters.

5. Did your calculated molarities agree? Explain any irregularities.

Inquiry Extension

Design an Experiment Determine the concentration of a vinegar solution without usingan indicator.

Error Analysis

CHEMLAB 18


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Ionization of a Triprotic AcidIonization of a Triprotic Acid



52

H3A

sO4(

aq) �

H2O

(l) 3

H3O

�(a

q) �

H2A

sO4�

(aq)

H2A

sO4�

(aq)

�H

2O(l

) 3H

3O�

(aq)

�H

AsO

42�(a

q)

HA

sO42�

(aq)

�H

2O(l

) 3H

3O�

(aq)

�A

sO43�

(aq)


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


1. H3AsO4 is a triprotic acid. What does the term triprotic mean?

2. What do all three of these equations have in common?

3. What property of water causes the ionization of H3AsO4 in aqueous solution?

4. Which step would require the least energy? Explain.

5. Why are double arrows used in the questions shown?

6. Write a similar set of equations for the complete ionization of phosphoric acid (H3PO4),which is another triprotic acid.

7. The formula for citric acid is H3C6H5O7. How many steps would occur in the completeionization of citric acid? Explain.

Ionization of a Triprotic AcidIonization of a Triprotic Acid



52


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Ionization Equations and ConstantsIonization Equations and Constants



53

Ionization Constants for Weak Acids

Acid Ionization equation Ka (298 K)

Hydrosulfuric H2S 3 H� � HS� 8.9 � 10�8

HS� 3 H� � S2� 1 � 10�19

Phosphoric H3PO4 3 H� � H2PO4� 7.5 � 10�3

H2PO4� 3 H� � HPO4

2� 6.2 � 10�8

HPO42� 3 H� � PO4

3� 2.2 � 10�13

Hydrofluoric HF 3 H� � F� 6.3 � 10�4

Methanoic HCOOH 3 H� � HCOO� 1.8 � 10�4

Ethanoic CH3COOH 3 H� � CH3COO� 1.8 � 10�5

(Acetic)

Carbonic H2CO3 3 H� � HCO3� 4.5 � 10�7

HCO3� 3 H� � CO3

2� 4.7 � 10�11

Hypochlorous HClO 3 H� � ClO� 4.0 � 10�8


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


1. Why do some acids have more than one ionization equation?

2. How do you know that the acids listed in the table are listed from strongest to weakest?

3. Which is stronger, the conjugate base of carbonic acid or the conjugate base of phos-phoric acid? Explain.

4. Write all the ionization equations for phosphorous acid (H3PO3), a weak acid.

5. Write the ionization constant expression for these acids.

a. hypochlorous acid

b. methanoic acid

6. Why can you assume that the concentrations of the ions in the ionization constant expres-sion for a weak acid are equal?

Ionization Equations and ConstantsIonization Equations and Constants



53


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


1314

pO

H12

1110

98

76

54

32

10

10�

110

�2

10�

310

�4

10�

510

�6

10�

710

�8

10�

910

�10

10�

1110

�12

10�

1310

�14

1[H

�]

10�

1310

�12

10�

1110

�10

10�

910

�8

10�

710

�6

10�

510

�4

10�

310

�2

10�

11

10�

14[O

H�]

10

pH

23

45

67

89

1011

1213

14

Neu

tral

Incr

easi

ng

bas

icit

yIn

crea

sin

gac

idit

y

The pH ScaleThe pH Scale



54


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


1. What is the pH of a solution with a [H�] of 10�8?

2. What is the pOH of a solution with a [OH�] of 10�11?

3. What is the pH of a solution that has a [OH�] of 10�2?

4. What is the pOH of a solution that has a [H�] of 10�5?

5. What do you notice about the product of [H�] and [OH�] for any aqueous solution?

6. What do you notice about the sum of pH and pOH for any aqueous solution?

7. Which is more acidic, a solution with a pH of 6 or one with a pH of 9?

8. Which is more basic, a solution with a pOH of 7 or one with a pOH of 12?

9. Which is more acidic, a solution with a pH of 5 or one with a pOH of 10?

10. Which is more basic, a solution with a pH of 8 or one with a pOH of 12?

11. Stomach contents can have a pH of 3. Are stomach contents acidic, basic, or neutral?

12. Pure water has a pOH of 7. Is pure water acidic, basic, or neutral?

13. Normal rain has a pH of approximately 6. Is normal rain strongly acidic, slightly acidic,neutral, slightly basic, or strongly basic?

14. Acid precipitation is often a problem in industrialized areas. What might you expect thepH of acid rain to be?

The pH ScaleThe pH Scale



54


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


pH

010

2030

40V

olu

me

NaO

H a

dd

ed (

mL)

Titr

atio

n A

5060

70

12 10 8 6 4 2 0

Equ

ival

ence

po

int

pH

010

20

Equ

ival

ence

po

int

Phen

olp

hth

alei

n

3040

Vo

lum

e N

aOH

ad

ded

(m

L)

Titr

atio

n B

5060

70

14 12 10 8 6 4 2 0

Titration GraphsTitration Graphs



55


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


1. NaOH is a strong base, HCl is a strong acid, and HCOOH is a weak acid.

a. Which titration is between a strong acid and a strong base?

b. Which titration is between a weak acid and a strong base?

2. What generalization can be made about the pH of the solution resulting from a completereaction between a strong acid and a strong base?

3. Does the graph for Titration A support your answer to question 2? Explain.

4. What generalization can be made about the pH of the solution resulting from a completereaction between a strong base and a weak acid?

5. Does the graph for Titration B support your answer to question 4? Explain.

6. During Titration A, what was the pH after 40.0 mL of NaOH was added to the HCl?

7. What was the pH after 40.0 mL of NaOH was added to the HCOOH during Titration B?

8. From the curves of the titrations, explain how you would know the equivalence point wasnear if a pH meter was used instead of an indicator.

9. Why was phenolphthalein a better choice for an indicator in Titration B than it wouldhave been for Titration A?

Titration GraphsTitration Graphs



55


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Scientific Notation Applied to Ka and Kb

Scientific notation expresses a number as a number between 1 and 10 multiplied by a power of ten.

Example Problem: The Ka of hydrogen fluoride (HF) is 0.00063. Express this number in scientific notation.

1. Move the decimal point to a place such that the resulting numberis between 1 and 10. In this example, it is between the 6 and the3, or 6.3.

2. Count the number of places the decimal point was moved. In thisexample, it was moved four places. Because each place to theright of the original decimal point indicates multiplying by 10�1,moving it four places indicates a power of 10�4.

3. Combine these two parts. The answer is 6.3 � 10�4.

Multiplying and Dividing Powers of Ten in Equilibria

1. When multiplying powers of ten, add the exponents.

2. When dividing powers of ten, subtract the exponents.

3. If the final number is to be written in scientific notation, check tobe sure that it is.

Example Problem: The [H�] in a solution of formic acid (HCOOH) is 2.5 � 10�3.Find Ka for a 3.4 � 10�2M solution of formic acid.

Ka � � �

� � 1.9 � 10�6�(�2) � 1.9 � 10�46.3 � 10�6��3.4 � 10�2

(2.5 � 2.5)(10�3�3)��

3.4 � 10�2(2.5 � 10�3)(2.5 � 10�3)��

3.4 � 10�2[H�][HCOO�]��

[HCOOH]

Powers of Ten Related to Acid and Base EquilibriaPowers of Ten Related to Acid and Base Equilibria



30


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


MATH SKILLS TRANSPARENCY WORKSHEET 30

1. What is the main advantage of writing large or small numbers in scientific notation?

2. Write each of the following values for Ka and Kb in scientific notation.

a. acetic acid: Ka � 0.000018

b. phenol: Ka � 0.00000000010

c. carbonic acid: Ka � 0.00000045

d. diethylamine: Kb � 0.00086

e. ethanolamine: Kb � 0.000032

f. oxalic acid: Ka � 0.056

g. phosphoric acid: Ka � 0.0072

h. pyridine: Kb � 0.0000000017

3. A 0.020M hypobromous acid (HBrO) solution has a hydrogen ion concentration of 6.8 � 10�6M. Find Ka for this acid.

4. A 0.15M solution of boric acid (H3BO3) has a H2BO3� ion concentration of

9.3 � 10�6M. Calculate Ka for this acid.

5. Ammonia (NH3) gas dissolves in water to form a base. The concentration of ammoniumions (NH4

�) in a 0.36M ammonia solution equals the concentration of hydroxide ionsand is 2.5 � 10�3M. Find Kb for ammonia.

Powers of Ten Related to Acid and Base EquilibriaPowers of Ten Related to Acid and Base Equilibria



Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Logs and Antilogs Related to pH and pOH

pH � �log[H�] pOH � �log[OH�]

pH � pOH � 14.0 [H�][OH�] � 1.0 � 10�14

[H�] � antilog(�pH) � 10�pH [OH�] � antilog(�pOH) � 10�pOH

Example Problems:

1. What is the pH of a solution in which the hydrogen ion concentration is 1.0 � 10�5M?

pH � � log[H�] � � log(1.0 � 10�5) � 5.00

2. What is the pOH of a solution in which the hydroxide ion concentration is 3.2 � 10�3M?

pOH � � log[OH�] � �log(3.2 � 10�3) � 2.49

3. What is the [H�] of a solution that has a [OH�] of 2.3 � 10�5M?

[H�] = � � 4.3 � 10�10M

4. What is the [H+] of a solution that has a pH of 1.70?

[H�] � 10�pH � 10�1.7 � 2.0 � 10�2M

5. What is the [OH�] of a solution that has a pH of 5.40?

pOH � 14.00 � pH � 14.00 � 5.40 � 8.60

[OH�] � 10�pOH � 10�8.6 � 2.5 � 10�9

1.0 � 10�14��2.3 � 10�5

1.0 � 10�14��

[OH�]

Logs and Antilogs Related to pH and pOHLogs and Antilogs Related to pH and pOH



31


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


1. In your own words, define a logarithm.

2. In your own words, define an antilogarithm.

3. How many times more acidic is a solution with a pH of 3 compared to one with a pH of 6?

4. Calculate the pH and pOH of each of the following solutions.

a. [H�] � 1.0 � 10�4M

b. [H�] � 7.9 � 10�6M

c. [OH�] � 1.0 � 10�2M

d. [OH�] � 2.3 � 10�8M

5. For each of the following solutions, if pH is given, find pOH. If pOH is given, find pH.

a. pOH � 1.2

b. pOH � 7.0

c. pH � 9.3

d. pH � 13.5

6. Determine [H�] and [OH�] for each of these solutions.

a. pH � 3.0

b. pH � 5.7

c. pOH � 9.7

d. pOH � 12.3

Logs and Antilogs Related to pH and pOHLogs and Antilogs Related to pH and pOH



31


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Acids and BasesAcids and Bases

Section 18.1 Acids and Bases: An IntroductionIn your textbook, read about the properties of acids and bases.

For each description below, write acid if it tells about a property of an acid or base if ittells about a property of a base. If the property does not apply to either an acid or abase, write neither. If it applies to both an acid and a base, write both.

1. Can turn litmus paper a different color

2. Reacts with certain metals

3. Contains more hydrogen ions than hydroxide ions

4. Feels slippery

5. Reacts with carbonates

6. Feels rough

7. Contains equal numbers of hydrogen and hydroxide ions

8. Tastes bitter

9. Tastes sour

In your textbook, read about the different models of acids and bases.

Use the terms below to complete the passage. You may use each term more than once.

The (10) model of acids and bases states that an acid contains

the element (11) and forms ions of this element when it is dissolved

in water. A base contains the (12) group and dissociates to produce

(13) ions in aqueous solution.

According to the (14) model, an acid donates

(15) ions, and a base accepts (16) ions.

According to this model, in an acid-base reaction, each acid has a

(17) , and each base has a (18) .


Arrhenius Brønsted-Lowry conjugate acid

conjugate base hydrogen hydroxide


Name Date Class

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 18.2 Strengths of Acids and BasesIn your textbook, read about strengths of acids.

Circle the letter of the choice that best completes the statement or answers the question.

1. Acid A and acid B are of equal concentration and are tested with a conductivity appara-tus. When the electrodes are placed in acid A, the bulb glows dimly. When they areplaced in acid B, the bulb glows more brightly. Which of the following is true?

a. Acid A is stronger than acid B.

b. Acid B is stronger than acid A.

c. Acid A and acid B are of equal strength.

d. No comparison of strength can be made from the results.

2. A chemical equation for the ionization of an acid uses a single arrow to the right (0) toseparate the reactant and product sides of the equation. Which of the following is true?

a. The arrow does not indicate relative strength. c. The ionizing acid is strong.

b. The ionizing acid is half ionized. d. The ionizing acid is weak.

3. Sulfuric acid is a strong acid. What is true about its conjugate base?

a. Its conjugate base is amphoteric.

b. Its conjugate base is strong.

c. Its conjugate base is weak.

d. No conclusion can be made regarding the strength of the conjugate base.

4. In solution, a weak acid produces

a. a mixture of molecules and ions. c. all molecules.

b. all ions. d. anions, but no hydronium ions.

5. Why are Ka values all small numbers?

a. The concentration of water does not affect the ionization.

b. The equilibrium is not stable.

c. The solutions contain a high concentration of ions.

d. The solutions contain a high concentration of un-ionized acid molecules.

6. Which of the following dissociates entirely into metal ions and hydroxide ions in solution?

a. a strong acid b. a strong base c. a weak acid d. a weak base

7. In general, compounds formed from active metals, and hydroxide ions are

a. strong acids. b. strong bases. c. weak acids. d. weak bases.



Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Section 18.3 Hydrogen Ions and pHIn your textbook, read about the ion product constant for water.


1. Write the simplest form of the chemical equation for the self-ionization of water.

2. Write the equilibrium constant expression, Keq, for this equation.

3. Write the expression for the equilibrium constant for water, Kw.

4. Why can the concentration of water be ignored in the equilibrium expression for water?

5. What is the numerical value of Kw at 298 K?

6. In solution, if the hydroxide ion concentration increases, what happens to the hydrogenion concentration?

7. If the concentration of hydroxide ions in solution is 1.0 � 10�6, what is the hydrogen ionconcentration?

8. Is the solution in question 7 acidic, basic, or neutral? Explain.

In your textbook, read about pH and pOH.

In the space at the left, write true if the statement is true; if the statement is false,change the italicized word or number to make it true.

9. The pH of a solution is the negative logarithm of its hydroxide ionconcentration.

10. Values for pH range from 0 to 14.

11. Stomach contents can have a pH of 2, which means that they arebasic.

12. The hydrogen ion concentration in a solution with a pH of 3 is two times greater than the hydrogen ion concentration in asolution with a pH of 5.



Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


13. The pH of a neutral solution at room temperature equals the pOHof the solution.

14. If the pH of a solution is 3, its pOH is 10.

15. The pH of a solution with a [H�] of 1 � 10�8 is 8.

16. The pH of a solution with a [OH�] of 1 � 10�6 is 6.

In your textbook, read about calculating the pH of acids and bases.

Solve each of the following problems. Show your work.

17. What is the pH of a 4.3 � 10�2M HCl solution? HCl is a strong acid.

18. Calculate the pH of a 5.2 � 10�3M H2SO4 solution? H2SO4 is a strong acid.

19. What is the pH of a 2.5 � 10�5M NaOH solution? NaOH is a strong base.

20. Calculate the pH of a 3.6 � 10�6M Ca(OH)2 solution. Ca(OH)2 is a strong base.

In your textbook, read about measuring pH.

Complete the passage.

Indicator paper can be used to measure the (21) of a solution. Indicators

are substances that are different (22) depending on the pH of the solution

tested. Another way to measure the acidity of the solution is the (23) , which

uses electrodes placed in solution to directly read the results.




Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Section 18.4 NeutralizationIn your textbook, read about neutralization and titration.

For each item in Column A, write the letter of the matching item in Column B.

Column A Column B

1. A chemical dye that changes color based on the pH of asolution

2. A method for using a neutralization reaction to determinethe concentration of a solution

3. A reaction in which an acid and a base react to produce asalt and water

4. A solution of known concentration

5. An ionic product of an acid-base reaction

6. The point in a titration in which an indicator changes color

7. The stoichiometric point of a titration

Complete the following table, indicating the formula and name of the salt formed by aneutralization reaction between the listed acid and base.

In the space at the left, write 1 through 4 to show the correct sequence of the steps inperforming a titration using a pH meter. Then, write 5 through 8 to sequence the stepsused to calculate the concentration of the unknown solution.

Sequence of Steps

13. Continue adding the standard solution to the solution of unknown concentrationuntil the equivalence point is reached.

14. Fill a buret with the standard solution.

15. Start adding the standard solution slowly, with mixing, to the solution ofunknown concentration, reading the pH at regular intervals.


a. acid-base indicator

b. end point

c. equivalence point

d. neutralization

e. salt

f. standard solution

g. titration

Acid Base Salt formula Salt name

8. HCl KOH KCl potassium chloride

9. H2SO4 Mg(OH)2

10. H3PO4 NaOH

11. HNO3 Fe(OH)3

12. H3PO4 Ca(OH)2


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


16. Use a pH meter to check the pH of a solution of known volume but unknownconcentration.

Calculation

17. Calculate the number of moles of acid or base in the volume of standard solu-tion added.

18. Use the mole ratio from the balanced equation to calculate the number of molesof reactant in the unknown solution.

19. Use the number of moles and volume of the unknown solution to calculatemolarity.

20. Write the balanced chemical equation for the neutralization reaction.

In your textbook, read about salt hydrolysis.

Complete the following concept map, using the terms acidic, basic, and neutral.

In your textbook, read about buffer solutions.

For each statement below, write true or false.

24. Buffers resist change in pH.

25. A buffer can be a mixture of a weak acid and its conjugate base.

26. An example of a buffer solution is a mixture of acetic acid and sodiumacetate.

27. A buffer solution changes pH only a small amount even if large amountsof acid or base are added.

28. A buffer system should contain considerably more acid than base.

29. Specific buffer systems should be chosen based on the pH that must bemaintained.



Parent acid and base

21. 22. 23.

Resulting aqueous solution

A strong acid and a weak base

A strong acid and a strong base

A weak acid and a strong base


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



Name Date Class

CHAPTER 18

Assessment



1. 4. 7.

2. 5. 8.

3. 6. 9.

Short Answer


10.

11.

12.

Extended Response


13.

14.

15.

SAT Subject Test: Chemistry

16. 17. 18.


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.

Chapter 19 Redox ReactionsMiniLab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

ChemLab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59


Study Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Chapter Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76


Table ofContents

57

Reproducible Pages


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

58 Chemistry: Matter and Change • Chapter 1 ChemLab and MiniLab Worksheets58 Chemistry: Matter and Change • Chapter 19 ChemLab and MiniLab Worksheets

mini LAB 19Observe a Redox Reaction

Applying Concepts The tarnish on silver is silver sulfide, which is formed when the sil-ver reacts with sulfide compounds in the environment. In this miniLAB, you will use anoxidation–reduction reaction to remove the tarnish from silver or a silver-plated object.

Materials aluminum foil, steel wool, small tarnished silver object, 400-mL beaker (orsize large enough to hold the tarnished object), baking soda, table salt, hot plate,beaker tongs

Procedure1. Read and complete the lab safety form.

2. Lightly buff a piece of aluminum foil with steel wool to remove any oxide coating.

3. Wrap the small tarnished object in the aluminum foil, making sure that the tarnishedarea makes firm contact with the foil.

4. Place the wrapped object in a 400-mL beaker and add a sufficient volume of tapwater to cover it completely.

5. Add about 1 spoonful of baking soda and about 1 spoonful of table salt to thebeaker.

6. Using beaker tongs, set the beaker and its contents on a hot plate, and heat until thewater is almost boiling. Maintain the heat for approximately 15 min, until the tarnishdisappears.

Analysis

1. Write the equation for the reaction of silver with hydrogen sulfide that yields silversulfide and hydrogen.

2. Write the equation for the reaction of the tarnish (silver sulfide) with the aluminumfoil that yields aluminum sulfide and silver.

3. Determine which metal, aluminum or silver, is more reactive. How do you know thisfrom your results?

4. Explain why you should not use an aluminum pan to clean silver objects.


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


CHEMLAB 19

Safety Precautions• WARNING: Silver nitrate is highly toxic and will stain skin and cloth-

ing.

ProblemHow can a series ofchemical reactions beused to determine whatwas dumped in a watersupply?

Materials0.1 M AgNO30.1 M Pb(NO3)20.1 M ZnSO4unknown solutionCu wirePb shotFe filingsMg turningstongs or forcepsdropper (4)24-well microscalereaction plate

Identify the Damaging DumperSomething is reacting with metals found on the hulls of many boats used on a nearby creek.

The investigator has determined that there are three possible culprits, each with a differentsource. Your job is to test the three potential pollutants and compare them with a sample fromthe creek. The animals that rely on the creek as their primary water source are depending on youto solve this mystery of the damaging dumper.

Pre-Lab


2. Prepare all written materials that you will take into the laboratory. Be sure to include safety precautionsand procedure notes. Use the data table below.

3. Review what a redox reaction is.

4. Review the steps in balancing a redox reaction using either the half-reaction method or the oxidation-num-ber method.

SMALL SCALE

Objectives• Observe redox reactions• Collect and analyze data• Draw conclusions based on your analysis

Trial AgNO3 HCL ZnSO4 Unknown

Cu

Pb

Fe

Mg

Observations


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Procedure


2. Create a table, like the one below, to record your data

3. Place the well plate on a sheet of white paper.

4. Place a piece of copper wire in four wells in thefirst row.

5. Repeat Step 4, by adding a small sample of ironfilings to wells in the second row.

6. Repeat Step 4, by adding a piece of lead shot towells in the third row.

7. Repeat Step 4, by adding a piece of magnesiumribbon to wells in the fourth row.

8. Count 20 drops of the silver nitrate solution(AgNO3) into each well in the first column.

9. Repeat Step 8, adding hydrochloric acid (HCl)in the second column.

10. Repeat Step 8, adding zinc sulfate (ZnSO4) inthe third column.

CHEMLAB 19


1. Summarize the results observed in each well. How did you know a chemical reactionoccurred?

2. Model Write a balanced reaction for each of the reactions you observed. In each one,identify the species being oxidized or reduced.

3. Conclude Based on your data, which solution was doing damage in the creek? Justifyyour answer.

4. Use Variables, Constants, and Controls Why was it important to compare the reac-tions of the unknown to more than one known solution?

AgNO3 Pb(NO3)2 ZnCO4 Unknown

Cu

Pb

Fe

Mg

Observations


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


5. Research Look up the MSDS for your chemical and report on what impact this chemicalwould have on the ecosystem.

6. Error Analysis Compare your results with those of other students in the laboratory.Explain any differences.

Inquiry Extension

Design an Experiment Hypothesize how you could remove this chemical from thecreek without further damaging the ecology of the area. Design an experiment to test yourhypothesis.

CHEMLAB 19


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


XX

XX

XX

XX

2MgO2Mg

Each loses2 electrons

Each gains2 electrons 2� 2�

2�2�

OOOOOO

OO

OO OO

OO

OO

OO

OOOO

OO

O2� 0

0

Oxidation and ReductionOxidation and Reduction



56


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


1. How do you know that the reaction for the chemical equation shown on the transparencyis a redox reaction?

2. What element is oxidized?

3. How do you know the element is oxidized?

4. What ion is formed as the result of this oxidation?

5. What element is reduced?

6. How do you know the element is reduced?

7. What ion is formed as the result of this reduction?

8. How many electrons were transferred during this reaction as it is shown? Explain.

9. Assuming the atoms shown are the only ones available, could magnesium atoms be oxidized if oxygen atoms were not reduced? Explain.

10. Draw a diagram similar to the one on the transparency to show what happens during theredox reaction between one atom of magnesium and a fluorine molecule.

11. In the reaction from question 10, what element is oxidized?

12. What ion is formed from this oxidation?

13. What element is reduced?

14. What ion is formed from this reduction?

15. How many electrons were transferred during this reaction as it is shown? Explain.

Oxidation and ReductionOxidation and Reduction



56


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Ch

ang

e: �

1re

du

ctio

n

�1

�1

�1

�1

00

Ch

ang

e: �

1o

xid

atio

n

oxi

diz

ing

agen

t

No

ch

ang

e in

oxi

dat

ion

nu

mb

er

red

uci

ng

agen

t

2 K

Br(

aq)

� C

l 2(a

q) 0

2K

Cl(

aq)

� B

r 2(a

q)

Equations for Redox ReactionsEquations for Redox Reactions



57


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


1. Did the bromide ion accept or donate an electron in this reaction? How do you know?

2. Locate the ion that has no change in oxidation number in this reaction.

a. What is the term applied to an ion that is present but does not enter into the actual

chemical reaction?

b. What ion in this equation is this type of ion?

3. Write the balanced net ionic equation for this reaction. What ion in the complete chemi-cal equation is not included in the net ionic equation?

4. What generalization can you make about what happens to an oxidizing agent during aredox reaction? Explain.

5. What generalization can you make about what happens to a reducing agent during aredox reaction? Explain.

6. Compare what happens in the equation on the transparency to what happens in the following equation:

Fe(s) � 2HCl(aq) 0 FeCl2(aq) � H2(g)

a. Assign an oxidation number to each ion, atom, or molecule shown in the above equation.

b. What is oxidized?

c. What is reduced?

d. What is the oxidizing agent?

e. What is the reducing agent?

f. What has no change in oxidation number?

Equations for Redox ReactionsEquations for Redox Reactions



57


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Balancing Equations:Oxidation-Number MethodBalancing Equations:Oxidation-Number Method



58

How to Balance Equations for Redox Reactionsby the Oxidation-Number Method

Write a chemical equation for the reaction,showing all reactants and products.

Determine the oxidation number of eachelement shown in the equation. Remember to treat a polyatomic ion as a single ion if itremains unchanged.

Draw a line connecting the atoms involvedin oxidation and another line connectingthe atoms involved in reduction. Write thenet change in oxidation number above orbelow each line.

Calculate coefficients to balance thenumber of electrons transferred in theredox part of the reaction.

If necessary, use the conventional methodof balancing equations to balance all atomsand charges.

1

2

3

4

5


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


1. Use the rules shown on the transparency to balance the equation for the reaction thatoccurs when you place solid magnesium into nitric acid (HNO3). Aqueous magnesiumnitrate and hydrogen gas form.

a. Step 1:

b. Step 2:

c. Step 3:

d. Step 4:

e. Step 5:

2. Use the rules shown on the transparency to balance the equation for the reaction thatoccurs when you mix solutions of nitric acid (HNO3), potassium chromate (K2CrO4),and iron(II) nitrate (Fe(NO3))3. Aqueous potassium nitrate, iron(III) nitrate, andchromium(III) nitrate form, along with water.

a. Step 1:

b. Step 2:

c. Step 3:

d. Step 4:

e. Step 5:

Balancing Equations:Oxidation-Number MethodBalancing Equations:Oxidation-Number Method



58


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Half-ReactionsHalf-Reactions



59

Various Oxidation–Reduction Reactions in Which Iron Is Oxidized

Oxidation Reduction Overall reaction half-reaction half-reaction

A. Fe � O2 0 Fe2O3 Fe 0 Fe3� � 3e� O2 � 4e� 0 2O2�

B. Fe � Cl2 0 FeCl3 Fe 0 Fe3� � 3e� Cl2 � 2e� 0 2Cl�

C. Fe � F2 0 FeF3 Fe 0 Fe3� � 3e� F2 � 2e� 0 2F�

D. Fe � HBr 0 FeBr3 � H2 Fe 0 Fe3� � 3e� 2H� � 2e� 0 H2

E. Fe � AgNO3 0 Fe(NO3)3 � Ag Fe 0 Fe3� � 3e� Ag� � e� 0 Ag

F. Fe � CuSO4 0 Cu � Fe2(SO4)3 Fe 0 Fe3� � 3e� Cu2� � 2e� 0 Cu

Balancing Equation A in the Table by the Half-Reaction Method:

Step 1 Rewrite the equation in complete ionic form. Do not include any coefficients.

Fe � O2 0 Fe3� � O2�

Step 2 Remove any spectator ions from the equation to derive the net ionic equation.

None are present in this equation.

Step 3 Write half-reactions for the redox reaction, showing the correct number of atomsindicated by the net ionic equation and the number of electrons lost or accepted.

Oxidation: Fe 0 Fe3� � 3e�; Reduction: O2 � 4e� 0 2O2�

Step 4 Balance the atoms of each type and the number of electrons lost and the numberof electrons gained in the half-reactions.

Oxidation: 4(Fe 0 Fe3� � 3e�) � 4Fe 0 4Fe3� � 12e�

Reduction: 3(O2 � 4e� 0 2O2�) � 3O2 � 12e� 0 6O2�

Step 5 Combine half-reactions into one complete equation.

4Fe � 3O2 � 12e� 0 4Fe3� � 6O2� � 12e�

Step 6 Simplify the equation by combining like terms.

4Fe � 3O2 � 12e� 0 4Fe3� � 6O2� � 12e�

Step 7 Complete the equation by returning any spectator ions, writing formulas as theywere in the original equation, and balancing any non-redox parts of the equation.

4Fe � 3O2 0 2Fe2O3

Step 8 Check all atoms on both sides of the equation to be sure the equation is balanced.

The equation is balanced.


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


1. In terms of electron transfer, what has happened in all of the oxidation half-reactionslisted in the table?

2. In terms of electron transfer, what has happened in all of the reduction half-reactionslisted in the table?

3. In all of these reactions, iron metal is oxidized. Is iron metal ever reduced? Explain.

4. Can iron ions be oxidized? Can they be reduced? Explain.

5. In which of the reactions shown in the table are spectator ions present? For each reactionthat contains a spectator ion, identify the spectator ion.

6. Use the half-reaction method to balance equations B–F from the table.

B. Fe � Cl2 0 FeCl3

C. Fe � F2 0 FeF3

D. Fe � HBr 0 FeBr3 � H2

E. Fe � AgNO3 0 Fe(NO3)3 � Ag

F. Fe � CuSO4 0 Cu � Fe2(SO4)3

Half-ReactionsHalf-Reactions



59


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Redox ReactionsRedox Reactions

Section 19.1 Oxidation and ReductionIn your textbook, read about redox reactions.


1. Redox reactions are characterized by

a. formation of a solid, a gas, or water.

b. replacement of one element in a compound by another element.

c. sharing of electrons.

d. transfer of electrons.

2. If a calcium atom loses two electrons, it becomes

a. a Ca2� ion. b. an oxidizing agent. c. oxidized. d. reduced.

3. In a redox reaction, an oxidizing agent is

a. balanced. c. oxidized.

b. increased in oxidation number. d. reduced.

4. An oxidation reaction occurs

a. at the same time a reduction reaction occurs.

b. before its corresponding reduction reaction occurs.

c. independently of any reduction reaction.

d. only when electrons are gained.

5. Consider the equation Ca(s) � O2(g) 0 2CaO(s).

In this reaction, calcium is oxidized because it

a. becomes part of a compound. c. loses electrons.

b. gains electrons. d. reacts with oxygen.

6. The number of electrons lost by an element when it forms ions is the element’s

a. charge. b. oxidation number. c. reduction number. d. shared electrons.

7. A loss of electrons is

a. oxidation. b. oxidation–reduction. c. redox. d. reduction.

8. Redox reactions can involve

a. ions only. c. uncharged atoms only.

b. molecules only. d. ions, molecules, or uncharged atoms.



Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


In your textbook, read about determining oxidation numbers.

For each redox reaction below, determine the oxidation number of each element present.Write your answer above each symbol for the element.

9. Cd(s) � NiO(s) 0 CdO(s) � Ni(s)

10. Fe(s) � CuSO4(aq) 0 FeSO4(aq) � Cu(s)

11. 2Sb(s) � 3I2(g) 0 2SbI3(s)

12. 2Cu2S(s) � 3O2(g) 0 2Cu2O(s) � 2SO2(g)

13. PbO2(s) � Pb(s) � 2H2SO4(aq) 0 2PbSO4(aq) � 2H2O(l)

14. NH4NO3(s) 0 2H2O(g) � N2O(g)

15. Fe2O3(s) � 3CO(g) 0 2Fe(s) � 3CO2(g)

In your textbook, read about oxidation, reduction, oxidizing agents, and reducingagents.

Use your answers from questions 9–15 to fill in the following table for the listed reactions. For each reaction, show what is oxidized, what is reduced, the oxidizing agent,and the reducing agent.



Equation Oxidized Reduced Oxidizing Agent Reducing Agent

16. Cd(s) � NiO(s) 0 CdO(s) � Ni(s)

17. Fe(s) � CuSO4(aq) 0FeSO4(aq) � Cu(s)

18. 2Sb(s) � 3I2(g) 0 2SbI3(s)

19. 2Cu2S(s) � 3O2(g) 02Cu2O(s) � 2SO2(g)

20. PbO2(s) � Pb(s) � 2H2SO4(aq) 02PbSO4(aq) � 2H2O(l)

21. NH4NO3(s) 0 2H2O(g) � N2O(g)

22. Fe2O3(s) � 3CO(g) 02Fe(s) + 3CO2(g)


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Section 19.2 Balancing Redox EquationsIn your textbook, read about balancing equations by using the oxidation numbermethod.


1. Why couldn’t the oxidation number method be used for balancing the following equation?

KI(aq) � Pb(NO3)2(aq) 0 PbI2(s) � KNO3(aq)

2. The conventional method of balancing equations can be used to balance redox equationsalso. Why is it easier to use the oxidation number method to balance redox equationssuch as Zn(s) � MnO2(s) � H2O(l) 0 Zn(OH)2(s) � Mn2O3(s)?

3. Why might you sometimes use a combination of the oxidation number method and theconventional method to balance a redox equation?

4. If you are balancing an ionic redox equation, why is it important to know whether thereaction takes place in an acidic solution? How might your answer change if the reactiontakes place in a basic solution?

5. What would be the advantage of using a net ionic equation to represent a redox reaction?



Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


Write the numbers 1 through 5 to place in order the steps used to balance an equationby the oxidation number method.

6. Determine the oxidation number of each element shownin the equation.

7. Draw a line connecting the atoms involved in oxidationand another line connecting the atoms involved inreduction.

8. If necessary, use the conventional method of balancingequations to balance all atoms and charges.

9. Use coefficients in front of formulas in the equation tobalance the number of electrons transferred in the redoxpart of the reaction.

10. Write a chemical equation, showing all reactants andproducts in the reaction.

In your textbook, read about balancing net ionic redox equations by the oxidation num-ber method.

Balance the following equations, using the oxidation number method for the redox partof the equation. If you need to, use the conventional method to balance the rest of theequation. Show your work.

11. N2(g) � H2(g) 0 NH3(g)

12. S8(s) � Cu(s) 0 Cu2S(s)

13. NO3�(aq) � Zn(s) 0 Zn(OH)4

2�(aq) � NH3(aq) in a basic 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

.

Name Date Class


In your textbook, read about half-reactions.

In the space at the left, write true if the statement is true; if the statement is false,change the italicized word or phrase to make it true.

14. A species is any kind of chemical unit involved in a process.

15. Glucose and sucrose are different types of sugars. A solution ofglucose, sucrose, and water contains exactly two different species.

16. A half-reaction is part of a decomposition reaction.

17. When magnesium reacts with oxygen, Mg 0 Mg2� � 2e� is thereduction half of the reaction.

18. A species that undergoes oxidation will donate electrons to anyatom that accepts them.

19. A species can be a molecule, an atom, or an electron.

20. Balancing equations by half-reaction is based on the number ofatoms transferred.

21. Balancing half-reactions involves balancing both atoms and charge.

22. In writing an equation in ionic form, ionic compounds are writtenas molecules.

23. The half-reaction SO2 � H2O � 2e� 0 SO42� � 4H� shows

that the reaction takes place in a basic solution.

In your textbook, read about identifying half-reactions.

For each of the following reactions, write the oxidation and reduction half-reactions.Identify each half-reaction as either oxidation or reduction. Then list the spectator ionsthat are present in the reaction. If no spectator ions are present, write none.

24. Ca(s) � Al(NO3)3(aq) 0 Al(s) � Ca(NO3)2(aq)

25. NO2(g) + NaOH(aq) 0 NaNO2(aq) + NaNO3(aq) + H2O(l)

26. HCl(aq) � KMnO4(aq) 0 KCl(aq) � MnCl2(aq) � Cl2(g) � H2O(l)

27. H3PO3(aq) � HNO3(aq) 0 H3PO4(aq) � NO(g) � H2O(l)




Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


In your textbook, read about balancing equations using half-reactions.

Use your answers from questions 11–13 to help you balance these equations. Show your work.

28. Ca(s) � Al(NO3)3(aq) 0 Al(s) � Ca(NO3)2(aq)

29. NO2(g) � NaOH(aq) 0 NaNO2(aq) � NaNO3(aq) � H2O(l)

30. HCl(aq) � KMnO4(aq) 0 KCl(aq) � MnCl2(aq) � Cl2(g) � H2O(l)

Balance the following equations, assuming all reactions take place in an acidic solution.Remember that charge, as well as atoms, must be balanced. Show your work.

31. NO3�(aq) � H2S(g) 0 S(s) � NO(g)

32. Cr2O72�(aq) � I�(aq) 0 Cr3�(aq) � I2(s)




Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



Name Date Class



1. 3. 5. 7.

2. 4. 6. 8.

Short Answer


9.

10.

Extended Response


11.

12.

13.


14. 16. 18.

15. 17.

CHAPTER 19

Assessment


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.

Chapter 20 ElectrochemistryMiniLab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

ChemLab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Teaching Transparency Masters and Worksheets . . . . . . . . . . . . . . . . . . . . . . . . . 88

Math Skills Transparency Masters and Worksheets . . . . . . . . . . . . . . . . . . . . . . . . . 94

Study Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

Chapter Assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

STP Recording Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

Table ofContents

83

Reproducible Pages


Name Date Class


mini LAB 20Observe Corrosion

Comparing and Contrasting A lot of money is spent every year correcting and pre-venting the effects of corrosion. Corrosion is a real-world concern of which everyoneneeds to be aware.

Materials iron nails (4); magnesium ribbon (2 pieces, each about 5 cm long); coppermetal (2 pieces, each about 5 cm long); 150-mL beakers (4); distilled water; saltwatersolution; sandpaper

Procedures 1. Read and complete the lab safety form.

2. Use sandpaper to buff the surfaces of four iron nails. Wrap two nails with magnesiumribbon and two nails with copper. Wrap the metals tightly enough so that the nailsdo not slip out.

3. Place each of the nails in a separate beaker. Add distilled water to one of the beakerscontaining a copper-wrapped nail and one of the beakers containing a magnesium-wrapped nail. Add enough distilled water to just cover the wrapped nails. Add saltwater to two additional beakers. Record your observations of the nails in eachbeaker.

4. Let the beakers stand overnight in the warmest place available. Examine the nails and solutions the next day and record your observations.

Analysis

1. Describe the difference between copper-wrapped nails in the distilled water and saltwater after standing overnight.

2. Describe the difference between the magnesium-wrapped nails in the distilled waterand in the salt water.

3. Explain the difference between a copper-wrapped nail and a magnesium-wrappednail.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


CHEMLAB 20

Safety Precautions• Always wear goggles and a lab apron.• The chemicals used in this experiment are eye and skin irritants. Wash

thoroughly if they are spilled on the skin.

ProblemHow can you measure thepotential of voltaic cells?

Objectives• Construct voltaic cells

using various combina-tions of metals for elec-trodes.

• Design the arrangementof the voltaic cells in amicroplate in such a wayas to use materials efficiently.

• Determine which metalsare the anode and cath-ode in voltaic cells.

• Compare the experimen-tal cell potential to thetheoretical value found inTable 21-1.

Materialsmetal strips

(approximately0.6 cm by 1.3 cm)of copper, alu-minum, zinc, andmagnesium

1M copper(II)nitrate

1M aluminumnitrate

1M zinc nitrate 1M magnesium

nitrate 24-well microplateBeral-type pipettes

(5)

voltmeterfilter paper

(6 pieces size 0.6 cm by 2.5 cm)

1M potassiumnitrate

forcepssteel wool or

sandpapertable of standard

reduction potentials

Measure Voltaic Cell PotentialsAvoltaic cell converts chemical energy into electrical energy. It

consists of two parts called half-cells. When two different metals,one in each half-cell, are used in the voltaic cell, a potential difference isproduced. In this experiment, you will measure the potential differenceof various combinations of metals used in voltaic cells and comparethese values to the values found in the standard reduction potentialstable.

Pre-Lab


2. Plan and organize how you will arrange voltaiccells in the 24-well microplate using the fourmetal combinations so that your time and materi-als will be used in the most efficient manner pos-sible. Have your instructor approve your planbefore you begin the experiment.

3. Prepare all written materials that you will takeinto the laboratory. Be sure to include safety precautions and procedure notes. Use the datatable on the next page.

4. Review the definition of a voltaic cell.

5. Review the purpose of a salt bridge in the voltaiccell. In this experiment, the filter paper stripssoaked in potassium nitrate are the salt bridges.


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


6. Review the equation to calculate cell potential.

7. For the voltaic cell Mg � Mg2� � Hg2� � Hg, iden-tify which metal is the anode and which metal isthe cathode. Which metal is being oxidized andwhich metal is being reduced? What is the theo-retical potential for this voltaic cell?

8. Review the equation to calculate percent error.

Procedure


2. Plan how you will arrange voltaic cells using thefour metal combinations in the 24-wellmicroplate. Have your instructor approve yourplan.

3. Soak the strips of filter paper in 2 mL of potassi-um nitrate solution. The strips are the salt bridgesfor the cells. Use forceps to handle the saltbridges.

4. Construct voltaic cells using the four metals and1 mL of each of the solutions. Put the metals intothe wells that contain the appropriate solution; forexample, put the zinc metal in the solution with

zinc nitrate. Use a different salt bridge for eachvoltaic cell. Connect the leads from the voltmeterto the metals. If you get a negative value forpotential difference, switch the leads on the metals.

5. Record in the data table which metals are theanode and the cathode in each cell. The blacklead of the voltmeter will be attached to theanode. The red lead will be attached to the cathode.

6. Record the cell potential of each cell.

7. Use forceps to remove the metals from themicroplate. Rinse them with water, then cleanthem with steel wool or sandpaper. Rinse themicroplate.

CHEMLAB 20

Anode metal

Cathode metal

Measured cellpotential (V)

Anode half-reactionand standardpotential

Cathode half-reaction andstandard potential

Theoretical cellpotential

% Error

Voltaic Cell Potential Data


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.



1. Apply In the data table, write the equations for half-reactions occurring at the anode and cathode in eachof the voltaic cells. Find the half-reaction potentials in Table 20.1, and record them in the table.

2. Calculate and record the theoretical potential for each voltaic cell.

3. Predict Using your data, rank the metals in order of most active to least active.

4. Calculate the percent error of the voltaic cell potential. Why is thepercent error large for some voltaic cells and small for others?

Inquiry Extension

Design an Experiment that would reduce the percent error discussed in Question 4.

Error Analysis

CHEMLAB 20


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Wire

Ions Ions

ZnSO4 solution CuSO4 solution

Zn Cu

Cl�

Cl�

K�

K�

Oxidation half-cell Reduction half-cell

Electrochemical CellElectrochemical Cell



60


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


1. What half-cell reaction takes place in each beaker?

Left beaker

Right beaker

2. What type of reaction (oxidation or reduction) takes place in each beaker?

Left beaker Right beaker

3. Which electrode is the anode and which is the cathode?

Anode Cathode

4. What atomic particles move through the wire, and in which direction do they move?

5. Which ions flow from the salt bridge into each beaker?


6. Write the overall cell reaction.

7. Represent the cell symbolically, using vertical lines to separate the components.

8. Use the following standard reduction potentials to calculate the standard cell potential, E0cell.

Zn2� � 2e– 0 Zn Cu2� � 2e– 0 Cu

E0Zn � �0.7618 V E0

Cu � �0.3419 V

9. How is an electrochemical cell useful?

Electrochemical CellElectrochemical Cell



60


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


2e�

2H�

O2

H2OH2

Collectorplate

e� flow

External load

Anode

Proton exchangemembrane

Cathode

1/2O2 � 2H� � 2e� 0H2OH2 0 2H� � 2e�

Hydrogen–Oxygen Fuel CellHydrogen–Oxygen Fuel Cell



61


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


1. What half-cell reaction takes place in the anode?

2. What half-cell reaction takes place in the cathode?

3. What type of reaction (oxidation or reduction) takes place in the anode and in the cathode?

anode cathode


5. Represent the cell symbolically, using vertical lines to separate the components.

6. Use the following standard reduction potentials to calculate the standard cell potential, E0cell.

2H+ � 2e– 0 H2�12

�O2 � 2H+ � 2e– 0 H2O

E0 � 0.0000 E0 � �1.229 V

7. What is the main useful product of the hydrogen–oxygen fuel cell?

8. Compare and contrast this cell reaction with the burning of hydrogen in air.

Hydrogen–Oxygen Fuel CellHydrogen–Oxygen Fuel Cell



61


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


An

od

eC

ath

od

e

Wat

erD

eple

ted

bri

ne

C

BA

Bri

ne

Ion

-per

mea

ble

mem

bra

ne

Na�

H2O

H2O

OH

Cl�

Electrolysis of BrineElectrolysis of Brine



62


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


Electrolysis of BrineElectrolysis of Brine



62

1. What two half-cell reactions are possible at the anode?

2. Which of these two reactions is more likely to occur at the anode if a high concentrationof chloride ions is present? Why?

3. What two half-cell reactions are possible at the cathode?

4. Which of these two reactions is more likely to occur at the cathode? Why?


6. Identify the products labeled A, B, and C on the transparency. (Hint: A and B are gases.)

A B C

7. Why is the hydrolysis of brine useful?

8. What must be done to cause the hydrolysis of brine to occur?

9. In what geographic areas do you think it would be most economical to set up thisprocess? Why?


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


Ga3� (aq) � 3e� 0 Ga(s)

Hg2�(aq) � 2e� 0 Hg(l)Step 1

Step 2

Step 3

Step 4

Step 5

Step 6

Look up the standard reduction potential for each half-reaction.

Determine which half-reaction will proceed as a reduction and whichwill proceed as an oxidation.

Rewrite the half-reactions in the correct directions.

Add the half-reactions.

Balance the overall cell reaction.

Calculate the standard cell potential.

Gallium half-reaction: oxidationMercury half-reaction: reduction

3�E � �0.549 V

; �0.851 V � (�0.549 V) � �1.400 V

0Ga �Ga

2�E � �0.851 V0Hg �Hg

E 0cell � E 0reduction � E 0oxidation

Ga(s) 0 Ga3�(aq) � 3e�

Hg2�(aq) � 2e� 0 Hg(l)

Ga(s) 0 Ga3�(aq) � 3e�

Ga(s) � Hg2�(aq) � 2e� 0 Ga3�(aq) � 3e� � Hg(l)

2Ga(s) � 3Hg2�(aq) 0 2Ga3�(aq) � 3Hg(l)

Hg2�(aq) � 2e� 0 Hg(l)

Calculating Standard Cell PotentialsCalculating Standard Cell Potentials



32


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


1. How do you decide which half-reaction will proceed as a reduction and which will proceed as an oxidation?

2. How do you decide in which direction to write the half-reactions?

3. Will the overall cell reaction shown on the transparency proceed spontaneously? Explainwhy or why not.

The following questions pertain to a voltaic cell in which the following half-reactions occur:

S(s) � 2e– 0 S2�(aq) E0S�S2� � �0.476 V

Ca2�(aq) � 2e– 0 Ca(s) E0Ca2��Ca � �2.868 V

4. Which half-reaction will proceed as a reduction?

5. Which half-reaction will proceed as an oxidation?

6. Rewrite the half-reactions in the correct directions.

7. Write a balanced equation for the overall cell reaction.

8. Calculate the standard cell potential.

Calculating Standard Cell PotentialsCalculating Standard Cell Potentials



32


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


0 50

10

9

8

7

6

5

4100 150 200

Time (minutes)

Bat

tery

vo

ltag

e (v

olt

s)

250 300 350 400

Alkaline battery

Nickel–cadmium battery

Comparing the Performance of BatteriesComparing the Performance of Batteries



33


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


The transparency shows how the voltage of two batteries changes when they are used topower the same kind of electrical device.

1. What is the starting voltage of each battery?

2. What is the remaining voltage of each battery after 100 minutes?

3. If the device requires a voltage of at least 6 V to work properly, how long will it workwith each battery?

4. How many of each battery would you need to keep the device working for 5 days if youreplaced each battery when its voltage dropped to 6 V?

5. Alkaline batteries are not rechargeable. Suppose each alkaline battery costs $1.25. Howmuch would it cost to run the device for 5 days with alkaline batteries if you replacedeach worn-out battery with a new one?

6. Nickel–cadmium batteries are rechargeable. Suppose each nickel–cadmium battery costs$10.00, and a battery charger costs $20.00. How much would it cost to run the device for5 days with nickel–cadmium batteries if you recharged them? (Assume you use twonickel–cadmium batteries, and that one battery can be fully recharged while the otherkeeps the device running. Include the cost of the charger, but ignore the cost of electricityto recharge the batteries.)

7. How long would you have to run the device before the cost of replacing alkaline batteriesexceeded the cost of two nickel–cadmium batteries and a charger?

Comparing the Performance of BatteriesComparing the Performance of Batteries



33


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


ElectrochemistryElectrochemistry

Section 20.1 Voltaic CellsIn your textbook, read about redox in electrochemistry.

Use each of the terms below just once to complete the passage.

Oxidation and reduction reactions can occur in separate solutions, as long as there are two

connections between the solutions. One connection is a(n) (1)

through which ions can flow. The other connection is a metal wire through which electrons

can flow. The flow of ions or electrons is known as a(n) (2) . The

complete setup, called a(n) (3) , can convert chemical energy into

electrical energy or electrical energy into chemical energy. Cells that convert chemical energy

to electrical energy by a spontaneous redox reaction are called (4)

cells.

Use the diagram of an electrochemical cell to answer the following questions.

5. The equation at the bottom of each beaker shows the half-reaction that is occurring in that beaker. What kind of reaction(oxidation or reduction) is occurring in each beaker?

Left beaker

Right beaker

6. Write the net ionic equation for this electrochemical cell.

7. In which direction do electrons move through the wire?

8. What kind of ions (positive or negative) move from the �-shaped tube into each beaker?



voltaic electrochemical cell electric current salt bridge

Wire

Ions Ions

Pt2� � 2e� 0 Pt Ni 0 Ni2� � 2e�

Pt Ni

Cl� K�

Cl�K�


Name Date Class

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.


In your textbook, read about the chemistry of voltaic cells.

For each item in Column A, write the letter of the matching item in Column B.

Column A Column B

9. One of the two parts of an electrochemical cell, whereeither oxidation or reduction takes place

10. An electrode where oxidation takes place

11. An electrode where reduction takes place

12. A measure of the amount of current that can be generatedfrom an electrochemical cell to do work

In your textbook, read about calculating cell electrochemical potential.


13. The tendency of an electrode to gain electrons is called

a. electron potential. c. reduction potential.

b. gravitational potential. d. oxidation potential.

14. A sheet of platinum covered with finely divided platinum particles is immersed in a 1M HCl solution containing hydrogen gas at a pressure of 1 atm and a temperature of25°C. The platinum sheet is known as a

a. standard platinum electrode. c. hydrogen chloride electrode.

b. standard hydrogen electrode. d. platinum chloride electrode.

15. The standard reduction potential of a half-cell is a measure of

a. concentration. c. temperature.

b. pressure. d. voltage.

16. Which of the following is the correct way to represent the equation,H2(g) + Cu2�(aq) 0 2H�(aq) � Cu(s)?

a. H2�H��Cu2��Cu c. Cu2��Cu�H2�H�

b. H��H2�Cu�Cu2� d. Cu�Cu2��H��H2

17. When connected to a hydrogen electrode, an electrode with a negative standard reductionpotential will carry out

a. reduction. c. both oxidation and reduction.

b. oxidation. d. neither oxidation nor reduction.



a. electrical potential

b. half-cell

c. cathode

d. anode


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


In your textbook, read about calculating cell electrochemical potential.

Use the table of standard reduction potentials below to answer the following questions.

18. Suppose you have two voltaic cells whose half-cells are represented by the followingpairs of reduction half-reactions. For each voltaic cell, identify which half-reaction willproceed in the forward direction as a reduction and which will proceed in the reversedirection as an oxidation.

Voltaic Cell #1 Voltaic Cell #2

Al3�(aq) � 3e� 0 Al(s) Tl3�(aq) � 3e� 0 Tl(s)

Ga3�(aq) � 3e� 0 Ga(s) Ga3�(aq) � 3e� 0 Ga(s)

19. Calculate the cell standard potential, E0cell, of each voltaic cell in question 20.

Voltaic Cell #1:

Voltaic Cell #2:

In your textbook, read about using standard reduction potentials.

Use the table of standard reduction potentials at the top of this page to answer the following questions.

20. Write the reduction and oxidation half-reactions for the following reaction:

Tl(s) � Al3�(aq) 0 Tl3�(aq) � Al(s)

reduction half-reaction:

oxidation half-reaction:

21. What is the standard reduction potential, E0, for each half-reaction in question 22?

E0reduction: E0

oxidation:

22. Calculate the cell standard potential, E0cell, for the reaction in question 22.

23. Will the reaction in question 22 occur spontaneously as written? Explain why or why not.

24. Will the reverse reaction, Tl3�(aq) � Al(s) 0 Tl(s) � Al3�(aq), occur spontaneously?Explain why or why not.



Half-reaction E0 (volts)

Al3� � 3e� 0 Al �1.662

Ga3� � 3e� 0 Ga �0.549

Tl3� � 3e� 0 Tl �0.741


Name Date Class

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 20.2 BatteriesIn your textbook, read about dry cells, the lead–acid storage battery, and lithium batteries.

Complete the table below by writing the type of battery described on the right. Chooseyour answers from the following types: lead–acid battery, lithium battery, nickel–cadmiumbattery, zinc–carbon dry cell.

In the space at the left, write true if the statement is true; if the statement is false,change the italicized word or phrase to make it true.

5. In a zinc–carbon dry cell, a carbon rod serves as the cathode.

6. Secondary batteries produce electric energy by means of redoxreactions that are not easily reversed.

7. One advantage of alkaline cells is that they are larger than drycells.

8. When a lead–acid battery is generating electric current, sulfuricacid is consumed and lead(II) sulfate is produced.

9. Dry cells and alkaline cells are examples of primary batteries.

10. Compared to most other batteries, lithium batteries store a smallamount of energy for their size.

11. Secondary batteries are rechargeable.

12. Each cell in a lead–acid battery generates about 12 volts.

13. Lead–acid batteries and nickel–cadmium batteries are examples ofsecondary batteries.


Type of Battery Description

1. The standard, rechargeable automobile battery

2. Often used in cordless drills, screwdrivers, and shavers because it is compact and rechargeable

3. The most commonly used voltaic cell from the 1880s until recently

4. Lightweight, long-lasting battery often used in watches and computers to maintain time and date settings


Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class


In your textbook, read about fuel cells.


14. The main purpose of a fuel cell is to produce

a. fuel. b. electric energy. c. chemical energy. d. heat.

15. In the hydrogen–oxygen fuel cell,

a. hydrogen is oxidized and oxygen is reduced. c. both oxygen and hydrogen are oxidized.

b. oxygen is oxidized and hydrogen is reduced. d. both oxygen and hydrogen are reduced.

16. What is the main difference between the reaction in a hydrogen–oxygen fuel cell and theburning of hydrogen in air?

a. When hydrogen burns in air, the oxidation and reduction reactions are separated.

b. The burning of hydrogen in air does not produce water.

c. The reaction in a fuel cell does not produce water.

d. The reaction in a fuel cell is very controlled.

In your textbook, read about corrosion.

Use the diagram below to answer the following questions.

17. What is the function of the sacrificial anode?

18. Name one metal that is commonly used as a sacrificial anode.

19. Galvanizing the iron tank (or pipe) would serve the same function as a sacrificial anode.What is galvanizing?

20. In what two ways does galvanizing protect iron?

Undergroundiron storage

tank

Sacrificial anode Wire




Name Date Class

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 20.3 ElectrolysisIn your textbook, read about reversing redox reactions and electrolysis.

In the space at the left, write the word or phrase in parentheses that correctly completesthe statement.

1. When a battery is being recharged, its redox reaction is reversedand energy is (absorbed, released) by the battery.

2. The use of electrical energy to cause a chemical reaction is called(combustion, electrolysis).

3. An electrochemical cell in which electrolysis is occurring is calledan (electrolytic, exothermic) cell.

4. In a Down’s cell, sodium metal and chlorine gas are producedfrom (molten, solid) sodium chloride.

5. The electrolysis of brine involves applying current to an aqueoussolution of (hydrochloric acid, sodium chloride).

6. The commercially important products of the electrolysis of brineare hydrogen gas, chlorine gas, and (oxygen gas, sodiumhydroxide).

In your textbook, read about the purification of metallic ores, electroplating, and aluminum production.


7. Copper can be produced by heating Cu2S in the presence of oxygen. Why must the copper then be subjected to electrolysis?

8. When an object is electroplated with silver, what is the anode and what is the cathode?

anode

cathode

9. The manufacture of aluminum begins with the electrolysis of aluminum oxide, Al2O3.What half-reaction occurs at the cathode?

10. Why are plants that produce aluminum often built close to large hydroelectric power stations?



Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.


Name Date Class

CHAPTER 20

Assessment



1. 3. 5. 7.

2. 4. 6. 8.

Short Answer


9.

10.

11.

Extended Response


12.

13.


14. 15.


110_CMC_FF_878764.indd Sec1:110110_CMC_FF_878764.indd Sec1:110 4/6/07 7:19:21 PM4/6/07 7:19:21 PMPrinter PDF

chapters 17–20 resources - wikispaces · pdf fileteacher guide and answers ... chemical...

Documents