Oxidation and Reduction Reactions Workbook

 

Period/Topic Worksheets Quiz

 

1. Oxidation, Reduction, Agents, & Reactions. WS 1

2. Lab: The Strength of Oxidizing Agents.

3. Oxidation Numbers Spontaneous Reactions WS 2 1

4. Oxidation Numbers, Application to Reactions. WS 3

5. Balancing Redox Half Reactions Acid/Base. WS 4 2

6. Balancing Redox Reactions in Acid/Base. WS 5

7. Standard Potentials Using Chart. WS 6 3

8. Electrochemical Cells. WS 7

9. Electrochemical Cells Lab.

10. Electrolytic Cells. WS 8 4

11. Electrolytic Cells Lab.

12. Application of Electrochemical Cells

13. Application of Electrolytic Cells WS 9 5

14. Corrosion, Redox Titrations, Breathalyzer WS 10 6

15. Review. Internet Review Practice Test 1

16. Review Practice Test 2

17. Test.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Worksheet #1 Redox Half Reactions and Reactions

 

Define each

 

1. Oxidation

2. Reduction

3. Oxidizing agent

4. Reducing agent

 

Write half reactions for each of the following atoms or ions. Label each as oxidation or reduction.

 

5. Al

6. S

7. O-2

8. Ba2+

9. N3-

10. Br2

11. P

12. Ca

13 Ga3+

14. S

15. H2

16. H+

17. F-

18. P3-

 

 

 

 

 

 

 

 


Balance each spontaneous redox equation. Identify the entities reduced and oxidized. State the reducing agent and the oxidizing agent.

 

19. Al & Zn2+

 

 

 

 

 

20. F2 & O2-

 

 

 

 

 

21. O2 & Ca

 

 

 

 

 

 

22. Al3+ & Li

 

 

 

 

 

 

 

Write the oxidation and reduction reactions for each redox reaction. The first one is done for you.

23. Fe2+ + Co Co2+ + Fe

Oxidation: Co Co2+ + 2e-

Reduction: Fe2+ + 2e- Fe

24. 3 Ag+ + Ni Ni3+ + 3 Ag

Oxidation:

Reduction:

25. Cu2+ + Pb Pb2+ + Cu

Oxidation:

Reduction:

 

26. O2 + 2 Sn O2- + 2 Sn2+

Oxidation:

Reduction:

27. Co2+ + 2 F- Co + F2

Oxidation:

 

Reduction:

 

28. There are nine formulas for oxidizing agents from questions 19 to 28. List them all. Only consider formulas that are on the left side of any equation. The first one is done for you.

Zn2+

 

29. There are nine formulas for reducing agents from questions 19 to 28. List them all. Only consider formulas that are on the left side of any equation. The first one is done for you.

 

Al

 

 

Worksheet #2 Redox Half Reactions and Reactions

 

1. State the Oxidation Number of each of the elements that is underlined.

a) NH3 _____ b) H2SO4 _____

c) ZnSO3 _____ d) Al(OH)3 _____

e) Na _____ f) Cl2 _____

g) AgNO3 _____ h) ClO4- _____

i) SO2 _____ j) K2Cr2O4 _____

k) Ca(ClO3)2 _____ l) K2Cr2O7 _____

m) HPO32- _____ n) HClO _____

o) MnO2 _____ p) KClO3 _____

q) PbO2 _____ r) PbSO4 _____

s) K2SO4 _____ t) NH4+ _____

u) Na2O2 _____ v) FeO _____

w) Fe2O3 _____ x) SiO44- _____

y) NaIO3 _____ z) ClO3- _____

aa) NO3- _____ bb) Cr(OH)4 _____

cc) CaH2 _____ dd) Pt(H2O)5(OH)2+ _____

 

 

ee) Fe(H2O)63+ _____ ff) CH3COOH _____

 

2. What is the oxidation number of carbon in each of the following substances?

a) CO _____ b) C _____

c) CO2 _____ d) CO32- _____

e) C2H6 _____ f) CH3OH _____

 

3. For each of the following reactants, identify: the oxidizing agent, the reducing agent, the substance oxidized and the substance reduced.

a) Cu2+ (aq) + Zn (s) Cu(s) + Zn2+ (aq)

Substance oxidized _____ Substance reduced _____

Oxidizing agent _____ Reducing agent _____

 

b) Cl2 (g) + 2 Na (s) 2 Na+ (aq) + 2 Cl- (aq)

Substance oxidized _____ Substance reduced ____

Oxidizing agent _____ Reducing agent _____

 

Worksheet # 3 Spontaneous and Non-spontaneous Redox Reactions

 

Describe each reaction as spontaneous or non-spontaneous.

 

1. Au3+ + Fe3+ Fe2+ + Au

 

2. Pb + Fe3+ Fe2+ + Pb2+

 

3. Cl2 + F- F2 + 2Cl-

 

4. S2O82- + Pb 2SO42- + Pb2+

 

5. Cu2+ + 2Br- Cu + Br2

 

6. Sn2+ + Br2 Sn4+ + 2Br-

 

7. Pb2+ + Fe2+ Fe3+ + Pb

 

8. Can you keep 1 M HCl in an iron container? If the answer is no, write a balanced equation for the reaction that would occur.

 

 

9. Can you keep 1 M HCl in an Ag container? If the answer is no, write a balanced equation for the reaction that would occur.

 

 

 

 

 

 

10. Can you keep 1 M HNO3 in an Ag container? If the answer is no, write a balanced equation for the reaction that would occur. (HNO3 consists of two ions H+ and NO3-)

 

 

 

 

 

11. Can you keep 1 M HNO3 in an Au container? If the answer is no, write a balanced equation for the reaction that would occur. (Remember, HNO3 consists of two ions H+ and NO3-)

 

 

 

 

 

12. Circle each formula that is able to lose an electron

 

O2 Cl- Fe Na+

 

13. Determine the oxidation number for the element underlined.

PbSO4 __________ ClO3- __________

HP032- __________ Na2O2 __________

CaH2 __________ Al2(SO4)3 __________

NaIO3 __________ C4H12 __________

 

14. Al3+ + Zn Al + Zn2+

 

Substance oxidized _______ Oxidizing agent ________

15. Cr2O72- + ClO2- Cr3+ + ClO4-

 

Substance reduced ________ Oxidizing agent ________

 

16. State the Oxidation Number of each of the elements that is underlined.

a) NH3 __________ b) H2SO4 __________

c) ZnCO3 __________ d) Al(OH)3 __________

e) Na __________ f) Cl2 __________

 

17. Balance the redox equation using the half reaction method.

Al & AgNO3

 

 

 

 

18. Circle each formula that is able to lose an electron

O2 Cl- Fe Na+

 

Determine the oxidation number for the element underlined.

19. PbSO4 __________

20. ClO3- __________

21. HPO32- __________

22. Na202 __________

23. CaH2 __________

24. NaIO3 __________

25. C4H12 __________

26. Al2(SO4)3 __________

27. Al3+ + Zn Al + Zn2+

 

Substance oxidized __________ Oxidizing agent __________

 

 

28. Cr2O72- + ClO2- Cr3+ + ClO4-

 

Substance reduced __________ Oxidizing agent __________

29. O3 + H2O + SO2 SO42- + O2 + 2H+

 

Substance oxidized __________ Reducing agent __________

 

30. 3As2O3 + 4NO3- + 7H2O + 4 H+ 6H3AsO4 + 4NO

 

Substance reduced __________ Reducing agent __________

 

 

 

 


Worksheet # 4 Balancing Redox Reactions

 

 

Balance each of the following half-cell reactions. (In each case assume that the reaction takes place in an ACIDIC solution.) Also, state whether the reaction is oxidation or reduction.

 

1. S2O32- SO42-

 

 

2. MnO4- Mn2+

 

 

3. As AsO43-

 

 

4. Cr3+ Cr2O72-

 

 

5. Pb2+ PbO2

 

 

6. SO42- S

 

 

7. NO3- NO

 

 

8. NO3- NH4+

 

 

9. BrO3- Br2

 


Balancing Half Cell Reactions

 

Balance in basic solution.

 

10. NO3- NO

 

 

11. MnO4- Mn2+

 

 

12. As AsO43-

 

 

13. Cr3+ Cr2O72-

 

 

14. Pb2+ PbO2

 

 

15. SO42- S

 

 

16. S2O32- SO42-

 

 

17. NO3- NH4+

 

 

18. BrO3- Br2

 

 

19. Determine if each of the following changes is oxidation, reduction or neither.

SO32- SO42- ________________

CaO Ca ________________

CrO42- Cr2O72- ________________

CrO42- Cr3+ ________________

2I- I2 ________________

IO3- I2 ________________

MnO4- Mn2+ ________________

ClO2- ClO- ________________

 

 

20. Cr2O72- + Fe2+ Cr3+ + Fe3+

Substance oxidized _____ Substance reduced _____

Oxidizing agent _____ Reducing agent _____

 

 

 

 

 

 

 

 

Worksheet # 5 Balancing Redox Reactions in Acid and Basic Solution

 

 

Balance each redox equation. Assume all are spontaneous. Use the half reaction method.

 

1. O2- + F2

2. Al + O2

3. K + Zn+2

 

 

 

Balance each half reaction in basic solution.

 

4. Cr2O72 - Cr3+

5. NO NO3-

6. SO42- SO2

7. MnO2 Mn2O3

 

 

Balance each redox reaction in acid solution using the half reaction method.

8. H2O2 + Cr2O72- O2 + Cr3+

 

 

 

9. TeO32- + N2O4 Te + NO3-

 

 

 

10. ReO4- + IO- IO3- + Re

 

 

 

11. PbO2 + I2 Pb2+ + IO3-

 

 

 

12. As H2AsO4- + AsH3

 

 

Balance each redox reaction in basic solution using the half reaction method.

 

13. O2 + Cr3+ H2O2 + Cr2O72-

 

14. Te + NO3- TeO32- + N2O4

 

 

 

 

15. IO3- + Re ReO4- + IO-

 

 

 

 

 

16. Pb2+ + IO3- PbO2 + I2

 

 

 

 

 

17. Cr2O72- + Hg Hg2+ + Cr3+

 

 

 

 

 

 

 

 

 

 

 

State of the change represents oxidation, reduction or neither. Use oxidation #s. Remember that if the oxidation # increases it means oxidation and when it decreases it mean reduction!

18. MnO2 Mn2O3

 

19. NH3 NO2

 

20. HClO4 HCl + H2O

 

21. O2 O2-

 

22. P2O5 P4H10

 

 

Determine the oxidation number

 

23. H2SO4 22. HSO4-

 

24. P4 23. NaH

 

25. UO3 24. Na2O2

 

26. U2O5 25. PbSO4

 

Worksheet # 6 Review

 

1. Describe each in your own words

 

a) Oxidation

b) Reduction

c) Oxidizing agent

d) Reducing agent

 

2. Write half reactions for each. Describe as oxidation or reduction. Circle all oxidizing agents.

a) Na

b) Ca

c) Al3+

d) F1-

e) N2

f) O2-

 


3. Write the reaction between the following: Use the half reaction method.

a) Ca + Al(NO3)3

 

 

b) Sn + AgNO3

 

 

c) Sn + Au(NO3)3

 

 

 

4. Circle each reducing agent: Cu Cu+ Al Al3+

 

5. Circle each oxidizing agent: F- F O2- O2

 

6. Ni+2 reacts with Mn, however, Al+3 does not react with Mn. Rank the oxidizing agents in order of decreasing strength. Rank the reducing agents in order of decreasing strength.

 

 

 

 

 

7. Ag+ reacts with Pb, however, Ca+2 does not react with Pb. Rank the reducing agents in order of decreasing strength. Rank the oxidizing agents in order of decreasing strength.

 

 

 

 

 

8. Cl2 reacts with Ag, however, Ag does not react with Mg+2. Rank the oxidizing agents in order of decreasing strength. Rank the reducing agents in order of decreasing strength.

 

 

 

 

 

9. Ni+2 reacts with Mn, however, Al+3 does not react with Mn. Rank the reducing agents in order of decreasing strength. Rank the oxidizing agents in order of decreasing strength.

 

 

 

 

10. Cl2 reacts with Br-, however, I2 does not react with Br-. Rank the oxidizing agents in order of decreasing strength. Rank the reducing agents in order of decreasing strength.

 

 

Classify as oxidation, reduction or neither.

 

11. SO42- S2-

 

12. MnO2 MnO4-

 

13. Cr2O72- CrO42-

 

14. IO3- I2

 

15. Given the following lab data

 

SnCl2 & Ni Spontaneous

Ni(NO3)2 & Fe Spontaneous

Cr(NO3)3 & Fe Non spontaneous.

 

i) Write three balanced equations.

 

 

 

 

ii) Rank the oxidizing agents in decreasing order of strength.

 

 

 

 

iii) Rank the reducing agents in decreasing order of strength.

 

 

 

 

iv) Will SnCl2 react with Cr? Explain?

 

 

 

 

v) Will Fe2+ react with Sn?

 

16. Determine the oxidizing and reducing agent. Balance in acidic solution.

 

MnO4- + H2S S + MnO

 

 

 

 

 

 

17. Determine the oxidizing and reducing agent. Balance in acidic solution.

 

SO42- + Br2 S2O32- + BrO3-

 

 

 

 

 

 

18. Balance in basic solution MnO4- + H2S S + MnO

 

 

 

 

 

 

 

19. Describe as spontaneous or non-spontaneous. Use your reduction potential chart.

a) ZnCl2 & Cu b) CuCl2 & NaCl

c) Br2 & Fe2+ d) H2S & Al3+

 

20. Can you keep HCl in a Zn container? Explain? What about an Au container?

 

 

 

 

 

 

Balance in basic solution

 

 

21. SO42- + Br2 S2O32- + BrO3-

 

Classify as an oxidizing agent, reducing agent or both based on its position on the table.

State the Eo or voltage of its position. Some of these are both, so state two voltages and indicate that it can be an oxidizing and reducing agent.

 

e.g. MnO4- (in acid) oxidizing agent 1.51 V

22. Br2 _________________ _________________

23. Fe2+ _________________ _________________

24. MnO4- (water) _________________ _________________

25. Ni _________________ _________________

26. Cr3+ _________________ _________________

27. H2O _________________ _________________

 

Indicate as spontaneous or non-spontaneous.

28. MnO4- (Alkaline) & Fe2+

29. HNO3 & Ag

30. HCl & Mg

 

Write each oxidation and reduction half reaction for each question above. Determine the Eo for each. Calculate the Eo for the overall reaction.

 

34.

 

 

35.

 

 

36.

 

Worksheet # 7 Electrochemical Cells

 

1. Oxidation is when electrons are .

 

2. Reduction is when electrons are .

 

3. The reducing agent undergoes .

 

4. The oxidizing agent undergoes .

 

5. A negative voltage means the reaction is .

 

6. In an electrochemical cell electrons exit the electrode which is .

 

7. In an electrochemical cell the reduction reaction is on the chart, while the

oxidation reaction is .

 

8. The cathode is the site of and the anode is the site of .

 

9. Anions migrate to the and cations migrate to the .

 

10. Anions have a charge and cations have a charge.

 

 

 

Draw and completely analyze each electrochemical cell.

 

11. Zn / Zn(NO3)2 ll Cu / Cu(NO3)2

 

 

 

 

 

 

 

 

 

 

12. Ag / AgNO3 ll H2 / HCl

 

 

 

 

 

 

 

 

 

 

 

Worksheet # 8 Electrolytic Cells

 

1. In an electrolytic cell, reduction occurs at the electrode and oxidation occurs at the electrode.

 

2. If there are two possible reduction reactions, the one on the chart occurs.

 

3. For reduction, the chart is read from to .

 

4. For oxidation, the chart is read from to and the sign of the voltage is .

 

5. If there are two possible oxidation reactions, the one on the chart occurs.

 

6. Corrosion of a metal is .

 

7. Electrolysis electrical energy.

 

8. Electrochemical cells electrical energy.

 

9. Electrolytic cells electrical energy.

 

10. What is the standard reference cell? Eo = v

 

Draw and completely analyze each electrolytic cell.

 

11. Molten NaCl

 

 

 

 

 

 

 

 

 

 

12. Aqueous Na2SO4

 

 

 

 

 

 

 

 

 

 

 

13. Liquid K2O

 

 

 

 

 

14. 1.0 M LiI

 

 

 

 

 

15. 250.0 mL of 0.200 M MnO4- reacts with excess SO3-2. How many grams of

MnO2 are produced? This is Chemistry 11 stoichiometry.

2MnO4- + 3SO32- + H2O → 2MnO2 + 3SO42- + 2OH-

 

 

 

 

 

16. Determine the oxidation number for each underlined atom.

MnO2 Cr2O72- IO3- C2O42- Al(NO3)3

 

 

17. Describe each term:

 

Salt bridge

 

Electrolyte

 

Anode

 

Cathode

 

Spontaneous

 

Electron affinity

 

18. What would happen if you used an aluminum spoon to stir a solution of FeSO4(aq)? Write a reaction and calculate Eo.

 

 

 

 

19. Draw an electrochemical cell using Cu and Ag electrodes.

 

 

 

 

 

 

20. 250.0 mL of 0.500 M MnO4- are required to titrate a 100.0 ml sample of SO3-2. Calculate the [SO3-2] 2MnO4- + 3SO32- + H2O → 2MnO2 + 3SO42- + 2OH-

21. How is the breathalyzer reaction used to determine blood alcohol content (you might need to look this up in your textbook?

 

 

 

 

22. 2H+ + Mg Mg2+ +H2

Oxidizing agent__________ Reducing agent_________

 

 

 

Worksheet # 9 Electrolytic, Electrochemical Cells & Application

 

Determine the half reactions for each cell and the cell voltage or minimum theoretical voltage and overall equation.

 

1. Ag / Pb electrochemical cell.

 

Anode: Cathode:

Anode reaction: Cathode reaction:

Overall reaction: Voltage:

 

2. ZnCl2(l) electrolytic cell (electrowinning)

 

Anode: Cathode:

Anode reaction: Cathode reaction:

Overall reaction: MTV:

 

3. CuSO4(aq) electrolytic cell (electrowinning)

 

Anode: Cathode:

Anode reaction: Cathode reaction:

Overall reaction: MTV:

 

 

4. The electrolysis of 1M NaI (electrowinning)

 

Anode: Cathode:

Anode reaction: Cathode reaction:

Overall reaction: MTV:

 

 

 

 

 

 

5. The reaction needed to make Al. The electrolyte is and its phase is (molten or aqueous).

 

To lower the mp. from 2000 oC to 800 oC is used.

Anode: Cathode:

Anode reaction: Cathode reaction:

Overall reaction:

 

6. The reaction needed to electroplate a copper penny with silver.

 

Anode: Cathode:

Anode reaction: Cathode reaction:

Possible Electrolyte:

 

7. The reaction needed to nickel plate a copper penny.

 

Anode: Cathode:

Anode reaction: Cathode reaction:

 

Possible Electrolyte:

 

8. The reaction used in the electrorefining of lead.

 

Anode: Cathode:

Anode reaction: Cathode reaction:

 

Possible Electrolyte:

 

 

Worksheet # 10 Electrolytic, Electrochemical Cells, Corrosion, & Cathodic Protection

 

Determine the half reactions for each cell and the cell voltage or minimum theoretical voltage.

 

1. Zn / Mg electrochemical cell

 

Anode: Cathode:

Anode reaction: Cathode reaction:

Overall reaction: Voltage:

 

2. The electrolytic cell used to produce Al.

 

Electrolyte: Phase (aqueous or molten)

Anode: Cathode:

Anode reaction: Cathode reaction:

Overall reaction:

3. The electrolysis KI(aq)

 

Anode: Cathode:

Anode reaction: Cathode reaction:

Overall reaction: MTV

 

4. The electrorefining of Pb

 

Anode: Cathode:

Anode reaction: Cathode reaction:

 

5. Nickel plating a iron nail.

 

Anode: Cathode:

Anode reaction: Cathode reaction:

Electrolyte

The -ve side of the power supply is connected to the

 

6. Draw an Ag/ Zn electrochemical cell.

 

 

 

 

 

 

 

7. Draw a KF(l) electrolytic cell.

 

 

 

 

 

 

 

8. Draw a KF(aq) electrolytic cell.

 

 

 

 

 

 

9. Draw a FeI2(aq) electrolytic cell.

 

 

 

 

 

 10. Draw a Cd/Pb electrochemical cell. Cd is not on the reduction chart, however, the Cd electrode gains mass and the total cell potential is 0.5 v. Determine the half-cell potential for Cd.

 

 

 

 

 

 

 

11. Write the overall reaction and describe the anode and cathode for a Zn/C, fuel, alkaline and lead/acid cell.

 

 

 

 

 

 

 

 

12. 2HIO3 + 5H2SO3 I2 + 5H2SO4 + H2O

oxidizing agent substance oxidized

substance reduced reducing agent

 

 

 

13. What is the electrolyte in a fuel cell?

 

 

14. What is the fuel in a fuel cell?

 

 

 

15. Describe the differences and similarities between an electrolytic and electrochemical cell.

 

 

 

16. Describe and give two examples of electrowinning.

 

 

 

17. Describe and give one example of electrorefining.

 

 

18. List three metals that can be won from aqueous solution.

 

 

 

19. List three metals that cannot be won from aqueous solution.

 

 

 

20. List the electrolyte in each of the following.

 

Fuel cell,

Alkaline battery

Dry Cell (Leclanche)

Lead acid battery

 

21. State two metals that can be used to cathodically protect Fe. Describe how they protect iron from corrosion.

 

 

 

22. Write the half reaction that describes the corrosion of iron.

 

 

 

 

23. Write the half reaction that describes the reduction reaction that occurs when iron corrodes in air and water.

 

 

 

24. Why does iron corrode faster in salt water?

 

 

 

25. Write the anode and cathode reaction in an electrolytic cell with a CaCl2(l) electrolyte.

 

 

 

 

26. Explain why you would choose Zn or Cu to cathodically protect iron?

 

 

 

27. Choose a suitable redox reactant to oxidize Cl- to ClO4- in a redox titration.

 

 

28. Describe as an electrochemical or electrolytic cell:

a) Fuel cell

b) Charging a car battery

c) Discharging a car battery

d) Ni plating

e) Industrial Al production

f) Cl2 production

 

 

29. Write the anode and cathode reactions for each of the above processes.

 

 

 

 

 

 

 

 

 

30. Al and AgNO3(aq) are mixed and the surface of the Al darkens. List the two oxidizing agents in decreasing strength. List the two reducing agents in decreasing strength.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

31. Analyze This

 

Label each anode and cathode.

Write each anode and cathode reaction.

Indicate the ion migration in each cell.

Determine the initial cell voltage of the electrochemical cell.

Determine the MTV for the electrolytic cell.

Will electrolysis occur?

Indicate electron flow.

Indicate all electrodes that gain mass.

Indicate all electrodes that lose mass.

What happens to [NO3-] in the Mg half-cell?

What happens to the [Ag+] in the Ag half-cell?

What happens to [Mg2+] in the Mg half-cell?

What is the equilibrium electrochemical cell potential?

What chemical is made at the Pt electrode on the right?

What chemicals are made at the Pt electrode on the left?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 
 

Quiz #1 Agents, Spontaneous Reactions, Oxidation #s, and Strength

 

1. In a redox reaction, the species that loses electrons

 

A. is oxidized

B. is called the cathode

C. gains mass at the electrode

D. decreases in oxidation number

 

2. Which of the following is the strongest oxidizing agent?

 

A. Cu2+

B. Pb2+

C. Ni2+

D. Sn2+

 

3. Metallic platinum reacts spontaneously with Au3+(aq) but does not react with Ag+(aq). The metals, in order of increasing strength as reducing agents, are

 

A. Ag, Pt, Au

B. Pt, Au, Ag

C. Au, Ag, Pt

D. Au, Pt, Ag

 

4. MnO4- + 5Fe2+ + 8H+ Mn2+ + 5Fe3+ + 4H2O The oxidizing agent in the reaction is

 

A. Fe2+

B. Fe3+

C. Mn2+

D. MnO4-

 

5. MnO4- + 5Fe2+ + 8H+ → Mn2+ + 5Fe3+ + 4H2O

During the reaction, electrons transfer from

 

A. Fe3+ to Fe2+

B. Fe2+ to MnO4-

C. MnO4- to Fe2+

D. MnO4- to Mn2+

 

6. As an element is oxidized, its oxidation number

A. increases as electrons are lost

B. decreases as electrons are lost

C. increases as electrons are gained

D. decreases as electrons are gained

 

 

7. A solution of 1.0 M Pb(NO3)2 will not react with a container made of

 

A. Cu

B. Fe

C. Sn

D. Zn

 

8. A spontaneous redox reaction occurs when a piece of iron is placed in 1.0 M CuSO4. The reducing agent is

 

A. Fe

B. Cu2+

C. H2O

D. SO42-

9. A substance is oxidized when it

 

A. loses protons

B. gains protons

C. loses electrons

D. gains electrons

 

10. A strip of titanium, Ti, is placed in 1.0 M Sn(NO3)2. The shiny surface of the titanium darkens, indication that a reaction has occurred. From this observation it may be concluded that

 

A. Ti2+ is a weaker reducing agent than Sn2+

B. Ti2+ is a weaker oxidizing agent than Sn2+

C. Ti2+ is a stronger reducing agent than Sn2+

D. Ti2+ is a stronger oxidizing agent than Sn2+

 

11. Consider the following redox reaction : Hg2+ + Cu → Hg + Cu2+ . In this reaction, Hg2+ is a

 

A. weaker reducing agent than Cu2+

B. weaker oxidizing agent than Cu2+

C. stronger reducing agent than Cu2+

D. stronger oxidizing agent than Cu2+

 

12. The species which gains electrons in a redox reaction

 

A. loses mass

B. is oxidized

C. is the oxidizing agent

D. increases in oxidization number

 

 

13. Samples of Uranium, Vanadium and Yttrium (U, V, Y) were placed in solutions containing the metallic ions U3+, V2+, and Y3+. The following observations were recorded.

 

Trial

Ion

Metal

Observation

1

U3+

Y

reaction

2

V2+

U

reaction

3

V2+

Y

reaction

4

Y3+

V

no reaction

 

The oxidizing agents from the strongest to the weakest are

 

A. V2+, U3+, Y3+

B. U3+, V2+, Y3+

C. Y3+, U3+, V2+

D. V2+, Y3+, U3+

 

 

Quiz #2 Agents, Spontaneous Reactions, Oxidation #s, and Strength

 

1. Which of the following pairs of ions will react spontaneously in a solution?

 

A. Cu2+ and Fe2+

B. Pb2+ and Sn2+

C. Co2+ and Cr2+

D. Mn2+ and Cr2+

 

2. When NO2 reacts to form N2O4 the oxidation number of nitrogen

 

A. increases by 2

B. increases by 4

C. increases by 8

D. does not change

 

3. Consider the following redox equation:

12H+(aq) + 2IO3-(aq) + 10Fe2+(aq) → 10Fe3+(aq) + I2(s) + 6H2O(l)

 

The reducing agent is

 

A. I2

B. H+

C. Fe2+

D. IO3-

 

 

4. The oxidation number of nitrogen increases in

 

A. NO3- → NO

B. N2O4 → NI3

C. NH3 → NH4+

D. NO2 → N2O5

 

5. Which of the following represents a balanced reduction half-reaction?

 

A. VO2 + 2H+ + 2e- → V2+ + H2O

B. VO2 + H2 → V2+ + H2O + le-

C. VO2 + 2H+ + le- → V2+ + H2O

D. VO2 + 4H+ + 2e- → V2+ + 2H2O

 

6. Consider the following half reaction: Sb2O3 + 6H+ + 6e- 2Sb + 3H2O

The oxidation number of antimony in Sb2O3

 

A. increases by 3

B. increases by 6

C. decreases by 3

D. decreases by 6

 

7. Consider the following unbalanced half-reaction HClO2 HClO

The balanced half-reaction would have

 

A. 1 electron on the left

B. 1 electron on the right

C. 2 electrons on the left

D. 2 electrons on the right

 

8. The oxidation number of platinum in Pt(H2O)42+ is

 

A. +2

B. 0

C. +4

D. +1/2

 

9. Consider the following half-reaction: BrO- → Br- (basic)

The balanced equation for the half-reaction is

 

A. BrO- + 2H+ + 2e- → Br- + H2O

B. BrO- + 2H+ → Br- + H2O + 2e-

C. BrO- + H2O → Br- + 2OH- + 2e-

D. BrO- + H2O + 2e- → Br- + 2OH-

 

10. Consider the following redox reaction:

2MnO4- + 5CH3CHO + 6H+ → 5CH3COOH + 2Mn2+ + 3H2O

The species that loses the electron is

 

A. H2O

B. MnO4-

C. CH3CHO

D. CH3COOH

 

11. Hydrogen has an oxidation number of 1 in

 

A. H2

B. NaH

C. H2O

D. KOH

 

12. Consider the following:

2NO3- + 4H+ + 2e- → N2O4 + 2H2O

 

This equation represents

 

A. reduction

B. oxidation

C. neutralization

D. decomposition

 

13. Which of the following half-reactions is balanced?

 

A. IO3- + 6H+ +5e- → I2 + 3H2O

B. IO3- + 6H+ + 4e- →1/2 I2 + 3H2O

C. IO3- + 6H+ → I2 + 3H2O + 5e-

D. IO3- + 6H+ + 5e- → I2 + 3H2O

 

14. Consider the following redox reaction: Al + MnO4- + 2H2O →Al(OH)4- + MnO2

The chemical species being oxidized is

 

A. Al

B. MnO4-

C. Al(OH)4-

D. MnO2

 

 

 

15. Consider the following redox reaction:

6H+ + 6I- + ClO3- → 3I2 + 3H2O + Cl-

 

The reducing agent is

 

A. I-

B. I2

C. H+

D. ClO3-

 

16. Nitrogen has an oxidization number of zero in

 

A. N2

B. NO2

C. NH3

D. HNO3

 

17. When MnO4- reacts to form Mn2+, the manganese in MnO4- is

 

A. reduced as its oxidation number increases

B. reduced as its oxidation number decreases

C. oxidized as its oxidation number increases

D. oxidized as its oxidation number decreases

 

18. Consider the following reaction:

2HNO3 + 3H2S → 2NO + 3S + 4H2O

 

The nitrogen in HNO3 undergoes

 

A. reduction

B. oxidation

C. electrolysis

D. neutralization

 

19. The oxidation number in carbon in CaC2O4 is

 

A. +2

B. +3

C. +4

D. +6

 


20. Consider the following redox reaction:

2Cr3+(aq) + 3Cl2(aq) + 7H2O(l) → Cr2O72-(aq) + 6Cl-(aq) + 14H+(aq)

 

The species which loses electrons is

 

A. Cl2

B. Cr3+

C. H2O

D. Cr2O72-

 

Quiz #3 Balancing Redox reactions- Acid & Base Cell Potentials

 

1. Consider the following overall reaction:

2Rh+ + Pb(s) 2Rh(s) + Pb2+- E0 = 0.73 V

The E0 for the half-reaction Rh+ + e- Rh is

 

A. -0.86 V

B. -0.60 V

C. +0.60 V

D. +0.86 V

 

2. Which of the following systems would be correct if the zinc half-cell would have been chosen as the standard instead of the hydrogen half-cell?

 

A. The reduction potentials of all the half-cells would remain unchanged

B. The reduction potentials of all the half-cells would increase by 0.76 V

C. The reduction potentials of all the half-cells would have positive values D. The reduction potentials of the hydrogen half-cell decrease by 0.76 V

 

3. Three beakers contain 1.0 M CuCl2. A piece of metal is placed in each of the beakers

 

BEAKER

SOLUTION

METAL

1

CuCl2

Zn

2

CuCl2

Ag

3

CuCl2

Ni

 

Reactions occur in

A. beaker 2 only

B. beakers 1, 2, and 3

C. beakers 1 and 2 only

D. beakers 1 and 3 only

 

 

 

4. Consider the following redox reaction:

3SO2 + 3H2O + ClO3- → 3SO42- + 6H+ + Cl-

The reduction half-reaction is

 

A. ClO3- + 6H+ → Cl- + 3H2O + 6e-

B. ClO3- + 6H+ + 6e- → Cl - + 3H2O

C. SO2 + 2H2O → SO42- + 4H+ + 2e-

D. SO2 + 2H2O + 2e- → SO42- + 4H+

 

5. What two substances are produced when Cr and 1.0 M MnO4- react in a basic solution?

 

A. Mn2+ and Cr3+

B. MnO2 and Cr3+

C. Mn2+ and Cr2+

D. MnO2 and CrO42-

 

6. Bromine, Br2, will react spontaneously with

 

A. I-

B. I2

C. Cl-

D. Cl2

 

7. The substances H2O2, H3PO4 and H2SO3 in order of increasing strengths as oxidizing agents are.

 

A H2O2, H3PO4, H2SO3

B. H2SO3, H3PO4, H2O2

C. H3PO4, H2SO3 , H2O2

D. H2O2,H2SO3 , H3PO4

 

8. Consider the following overall equation for an electrochemical cell:

3Ag+ + Cr → Cr3+ + 3Ag

At standard conditions ,the initial cell voltage is

 

A. +0.06 V

B. +0.39 V

C. +1.21 V

D. +1.54 V

 


9. A solution of 1.0 M Co(NO3)2 should be stored in a container made of

 

A. tin

B. zinc

C. aluminum

D. magnesium

 

10. A strong oxidizing agent has a

 

A. weak attraction for electrons

B. strong attraction for electrons

C. weak ability to become reduced

D. strong ability to become oxidized

 

11. The two species which react spontaneously in acidic solutions are

 

A. IO3- and I2

B. SO42- and S

C. BrO3- and Br -

D. AuCl4- and Au

 

12. Consider the following redox reaction:

Co2+(aq) + 2Ag(s) → 2Ag+(aq) + Co(s)

The reaction is

 

A. spontaneous and Eo is positive.

B. spontaneous and Eo is negative.

C. non-spontaneous and Eo is positive.

D. non-spontaneous and Eo is negative

 

13. Referring to the data booklet, which of the following can act as an oxidizing agent but not as a reducing agent?

 

A. Zn

B. Cl-

C. Sn2+

D. Fe3+

 

14. Which equation represents a redox reaction?

 

A. Pb2+ + 2Cl- → PbCl2

B. CaO + CO2 → CaCO3

C. Mg + 2HCl → MgCl2 + H2

D. HCl + NaOH → NaCl + H2O

 

15. In a redox reaction, ClO- was converted to Cl- in a basic solution. The balanced half-reaction for this process is

 

A. ClO- + H2O + 2e- → Cl- + 2OH-

B. ClO- + 2OH- → Cl- + 2e- + H2O

C. ClO- + H2O → Cl- + 2e- + 2OH-

D. ClO- + 2OH- + 2e- → Cl- + H2O

 

 

Quiz #4 Electrochemical Cells/Electrolytic Cells

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1. In the electrochemical call above, the electrons flow from

 

A. zinc to lead and the mass of zinc increases

B. zinc to lead and the mass of lead increases

C. lead to zinc and the mass of zinc increases

D. lead to zinc and the mass of lead increases

 

2. The initial cell voltage is

 

A. -0.89 V

B. -0.63 V

C. +0.63 V

D. +0.89 V

 

3. In an operating lead-zinc electrochemical cell shown above, the cathode

 

A. gains mass as anions are reduced

B. loses mass as anions are reduced

C. gains mass as cations are reduced

D. loses mass as cations are reduced

 


4. The equation for the half-reaction at the anode is

A. Zn2+ + 2e- → Zn

B. Pb2+ + 2e- → Pb

C. Zn → Zn2+ + 2e-

D. Pb → Pb2+ + 2e-

 

5. The equation for the half-reaction at the cathode is

A. Zn2+ + 2e- → Zn

B. Pb2+ + 2e- → Pb

C. Zn → Zn2+ + 2e-

D. Pb → Pb2+ + 2e-

 

6. The direction of electron flow in an electrochemical cell is from

 

A. anode to cathode through the external wire

B. cathode to anode through the external wire

C. anode to cathode through the external wire and back through the salt bridge

D. cathode to anode through the external wire and back through the salt bridge

 

7. Which of the following is formed at the anode during the electrolysis of 1.0 M NaI?

A. I2

B. O2

C. H2

D. Na

 

8. As this cell operates

A. Cl- is oxidized at the anode

B. Mg2+ is oxidized at the anode

C. Cl- is oxidized at the cathode

D. Mg2+ is oxidized at the cathode

 

 

 

 

 

 

 

 

 

 

 

 

9. In an operating electrochemical cell, the anions migrate

A. towards the anode through the wire

B. towards the cathode through the wire

C. towards the anode through the salt bridge

D. towards the cathode through the salt bridge

 

 
 

 

 

 

 

 

 

 

 

 

 

 

 

10. As the above electrochemical cell operates

 

A. nitrate ions migrate into the copper half-cell

B. copper(II) ions migrate through the salt bridge

C. magnesium ions migrate through the salt bridge

D. potassium ions migrate into the magnesium half-cell

 

11. In the above electrochemical cell, the reaction at the anode is

 

A. Cu → Cu2+ + 2e-

B. Cu2+ + 2e- → Cu

C. Mg → Mg2+ + 2e-

D. Mg2+ + 2e- → Mg

 

12. In the above electrochemical cell, the initial voltage is

 

A. 2.03 V

B. 2.52 V

C. 2.71 V

D. 2.89 V

 

13. Which of the following aqueous solutions produces H2(g) and O2(g) during electrolysis

A. 1.0 M KI

B. 1.0 M CuI2

C. 1.0 M K2SO4

D. 1.0 M CuSO4

 

14. In the electrolysis of molten zinc chloride, the half-reaction at the anode is

 

A. Cl2 + 2e- → 2Cl-

B. 2Cl- → Cl2 + 2e-

C. Zn2+ 2e- → Zn

D. Zn → Zn2+ + 2e-

 

 

 

 

 

 

 

 

 

 

 

 

 

15. The initial cell voltage at 25oC is

 

A. -1.06 V

B. -0.54 V

C. +0.54 V

D. +1.06 V

 

16. The balanced equation for the overall reaction is

 

A. Ni+(aq) + Ag(s) → Ag+(aq) + Ni(s)

B. Ni(s) + Ag+(aq) → Ag(s) + Ni+(aq)

C. Ni2+(aq) + 2Ag(s) → 2Ag+(aq) + Ni(s)

D. Ni(s) + 2Ag+(aq) → 2Ag(s) + Ni2+(aq)

 

17. This redox reaction occurs because

 

A. Ag(s) is a stronger oxidizing agent than Ni(s)

B. Ag(s) is a weaker reducing agent than Ni(s)

C. Ag+(aq) is a stronger reducing agent than Ni2+(aq)

D. Ag+(aq) is a weaker oxidizing agent than Ni2+(aq)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

18. The direction of the electron flow is

 

A. from Au to Pb through the wire

B. from Pb to Au from the wire

C. from Au to Pb through the salt bridge

D. from Pb to Au through the salt bridge

 

19. As the cell operates

 

A. NO3- and K+ will migrate toward the Pb half-cell

B. NO3- and K+ will migrate toward the Au half-cell

C. NO3- migrates toward the Pb half-cell and K+ will migrate toward the Au

D. NO3- migrates toward the Au half-cell and K+ will migrate toward the Pb

 

20. The initial voltage is

 

A. -1.37 V

B. 0.00 V

C. 1.37 V

D. 1.63 V

 

21. Which of the following is a balanced half-reaction in base?

 

A. Cl2 + 3H2O → ClO3- + 6H+ + 5e-

B. Cl2 + 6OH- → ClO3- + 5e- + 3H2O

C. Cl2 + 6H2O → 2ClO3- + 12H+ + 10e-

D. Cl2 + 12OH- → 2ClO3- + 6H2O + 10e-

 

22. In which of the following unbalanced equations does chromium undergo oxidation?

 

A. Cr3+ → Cr

B. Cr3+ → Cr2+

C. Cr3+ → Cr2O72-

D. CrO42- → Cr2O72-

 

Quiz #5 Application of Cells

 

 

1. The corrosion of iron can be prevented by attaching a piece of zinc to the iron because the

 

A. iron acts as an anode

B. zinc reduces more readily than iron

C. electrons flow from the zinc to the iron

D. iron ions form more readily than zinc ions

 

2. An iron spoon is electroplated with copper. The equation representing the reduction reaction is

 

A. Cu2+(aq) + 2e- → Cu(s)

B. Cu(s) → Cu2+(aq) + 2e-

C. Fe2+(aq) + 2e- → Fe(s)

D. Fe(s) → Fe2+(aq) + 2e-

 

3. In an operating zinc-copper electrochemical cell, the oxidizing agent

 

A. loses electrons at the anode

B. loses electrons to the cations

C. gains electrons at the cathode

D. gains electrons from the anions

 

4. An example of electro refining is the

 

A. extraction of aluminum from bauxite

B. purification of lead from an impure anode

C. recovery of zinc from a zinc sulphide solution

D. production of chlorine from a sodium chloride solution

 

5. Electroplating always involves the

 

A. oxidation of anions

B. reduction of cations

C. reduction at the anode

D. oxidation at the cathode

 

 

 6. Hydrogen and oxygen react to provide energy in a

 

A. dry cell

B. fuel cell

C. alkaline cell

D. lead-acid storage cell

 

7. En electrolytic process is used to purify impure lead. The electrodes are

 

 

 

ANODE

CATHODE

A.

carbon

impure lead

B.

pure lead

carbon

C.

pure lead

impure lead

D.

impure lead

pure lead

 

 

 

 

 

 

 

 

 

8. In the cell below the half-reaction at the cathode is

 

A. Cu2+ + 2e- → Cu(s)

B. 2SO42- → S2O82- + 2e-

C. H2O → O2(g) + 2H+ + 2e-

D. 2H2O + 2e- → H2(g) + 2OH-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 9. In the electrolysis of molten PbBr2, the products at the anode and cathode are

 

A.

B.

C.

D.

 

 
ANODE (INERT)

CATHODE (INERT)

Br2

H2

O2

Pb

Pb

Br2

Br2

Pb

 

 

10. Under which conditions could an electrochemical cell provide 0.93V?

 

A.

B.

C.

D.

 

 
Anode

Cathode

Cu

Mg

Mg

Cu

Ag

Pb

Pb

Ag

 

11. The reduction reaction in the above electrochemical cell is

 

A. Pb2+ + 2e- Pb

B. Pb Pb2+ + 2e-

C. Ag+ + e- Ag

D. Ag Ag+ + e-

 

12. An industrial process involving electrolysis is the reduction of

 

A. water forming oxygen gas

B. water forming hydrogen gas

C. sea water forming chlorine gas

D. sea water forming bromine liquid

 

13. To plate a nickel coin with copper

 

A. the nickel coin must be the cathode

B. the cathode must be made of copper

C. the electrons must flow to the anode

D. the solution must contain nickel ions

 

14. Which of the following ions can be reduced from an aqueous solution

 

A. Ba2+

B. Al3+

C. Sn2+

D. Na+

 

 

15. The principal function of a fuel cell is to

 

A. produce fuel

B. electrolyze fuel

C. produce hydrogen

D. produce electricity

 

16. If a piece of nickel is to be gold-plated using an electrolytic process, which half-reaction occurs at the cathode?

 

A. Ni → Ni2+ + 2e-

B. Ni2+ + 2e- → Ni

C. Au → Au3+ + 3e-

D. Au3+ + 3e- → Au

 

17. Consider the following redox reaction

As2O3 + 2NO3- + 2H2O + 2H+ → 2H3AsO4 + N2O3

In this reaction, nitrogen

 

A. loses electrons and increases in oxidation number

B. gains electrons and increases in oxidation number

C. loses electrons and decreases in oxidation number

D. gains electrons and decreases in oxidation number

 

 

18. In an electrochemical cell, the cathode

 

A. is reduced

B. loses mass

C. is the reducing agent

D. is the site of reduction

 

19. When 1.0 M NaI is electrolyzed, bubbles of gas form on one electrode and a reddish-brown substance forms on the other. The half-reaction at the cathode is

 

A. 2I- → I2 + 2e-

B. Na+ + e- → Na

C. H2O + O2 + 2H+ + 2e-

D. 2H2O +2e- → H2 + 2OH-

 

 

 

 

 

 

 Quiz #6 Corrosion & Cathodic Protection Titration

 

1. Which of the following metals could be used to cathodically protect a sample of lead?

 

A. iron

B. gold

C. silver

D. copper

 

2. A piece of iron can be prevented from corroding by

 

A. making it a cathode

B. placing it in an acidic solution

C. attaching a small piece of lead to it

D. attaching a small piece of gold to it

 

3. To determine the [Fe2+] in a solution of FeSO4 by a redox titration, a suitable reagent would be an acidified solution of

 

A. Cr3+

B. Mn2+

C. SO42-

D. Cr2O72-

 

4. As a metal corrodes,

 

A. it gains electrons

B. it becomes reduced

C. it acts as a reducing agent

D. its oxidation number decreases

 

 

5. Which method will cathodically protect a piece of iron?

 

A. Paint the iron

B. Cover the iron with grease

C. Attach a piece of lead tot he iron

D. Attach a piece of magnesium to the iron

 

6. Corrosion of iron can be prevented by attaching a piece of

 

A. Mn

B. Cu

C. Pb

D. Sn

 

 

7. A student attempted to determine the Eo (volts) of the following half-reaction:

Pd2+ + 2e- → Pd Pd2+ reacts with Cu(s) but not with Hg(l).

Based on the above, the Eo (volts) of a Pd half-cell is

 

A. less than 0.34 V

B. greater than 1.50 V

C. greater than 0.85 V but less than 1.50 V

D. greater than 0.34 V but less than 0.85 V

 

8. Consider the following redox equation:

Br2 + SO2 + Na2SO4 + 2H2O → 2H2SO4 + 2NaBr

Which of the following is gaining electrons?

 

A. Br2

B. SO2

C. H2O

D. Na2SO4

 

9. The reaction that occurs when pieces of lead, zinc, copper and silver are placed in a solution of Ni(NO3)2 is

 

A. Pb + Ni2+ → Pb2+ + Ni

B. Zn + Ni2+ → Zn2+ + Ni

C. Cu + Ni2+ → Cu2+ + Ni

D. 2Ag + Ni2+ → 2Ag+ + Ni

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

10. In the electrochemical cell above, the electrons flow from

 

A. copper to lead through the wire

B. lead to copper through the wire

C. copper to lead through the salt bridge

D. lead to copper through the salt bridge

 

11. In the electrochemical cell above, the initial Eo value is

 

A. 0.03 V

B. 0.21 V

C. 0.29 V

D. 0.47 V

 

12. A reaction that occurs during the corrosion of iron is

 

A. Fe + 3e- → Fe3+

B. Fe → Fe2+ + 2e-

C. Fe2+ + 2e- → Fe

D. Fe3+ + e- → Fe2+

 

13. Consider the following reaction

Zn(s) + 2Ag+(aq) → Zn2+(aq) + 2Ag(s)

What volume of 0.500 M AgNO3 is required to react completely with 6.54 g of zinc?

 

A. 0.0131 L

B. 0.0262 L

C. 0.200 L

D. 0.400 L

 

 Redox Web Review

1) Which most readily gains electrons?

Cu

Cu2+

Fe2+2

Zn2+

Au3+

2) Which most readily loses electrons?

Hg(l)

Cu2+

Sn4+

Ba

Al

Calculate the cell potentials or voltages (E0) Indicate spontaneity.

3. Cl2 + 2Br- → 2Cl- +Br2

 

 

4. 2MnO4- + 5Pb + 16H+ 2Mn2+ + 8H2O + 5Pb2+

 

 

5. Will AgNO3 react with Zn? Write a balanced redox reaction and calculate Eo

 

 

6. What would happen if you used an iron spoon to stir a solution of Al2(SO4)3(aq) ? Write a balanced redox reaction and calculate Eo.

 

 

 

 

 

7. What are the differences between an electrochemical cell and an electrolytic cell?

Electrochemical cell

Electrolytic cell

 

 

 

 

 

 

 

 

8. What are the similarities between an electrochemical cell and an electrolytic cell?

Electrochemical cell or Electrolytic cell

 

 

 

 

9. State how you would determine each of the following in an electrochemical or electrolytic cell.

 

Electrochemical Cell

Electrolytic Cell

The site of reduction

 

 

The site of oxidation

 

 

The +ve electrode

 

 

The -ve electrode

 

 

The anions migrate to the

 

 

The cations migrate to the

 

 

The electrode that gains mass

 

 

The electrode that loses mass

 

 

The electrons flow from

 

 

10. Draw an operating electrochemical cell using an Al half-cell and a Mg half-cell. Label the parts of the electrochemical cell including the anode or cathode, and all reagents and materials used. Write the reactions and determine the E0.

 

 

 

 

11. Write the half reaction that occurs at each electrode during the electrolysis of aqueous

1.0 M NaI.

Anode :

Cathode :

What is the minimum required voltage for this process?

12. Write the half reaction that occurs at each electrode during the electrolysis of molten NaI.

Anode :

Cathode :

What is the minimum required voltage for this process?

13. Aluminum is produced industrially from aluminum oxide, Al2O3. Demonstrate your understanding of this process by

(i) Describing how the process is carried out,

 

(ii) Writing equations of the reactions involved in the process, and

 

(iii) Describing how the problem of the high melting point ofAl2O3 is overcome.

 

 

14. Consider the following redox data:

3V + 2Ga3+ 3V2+ + 2Ga Eo = +0.64 V

3V2+ + 2Al 3V + 2Al3+ Eo = +0.46 V

Based on these observations, a student concludes that Ga+3 and Al will react spontaneously. List the oxidizing agents in order of decreasing strength. Write reduction reactions for each. Determine the strongest reducing agent. Determine if Ga+3 and Al will react spontaneously.

 

15. Balance the equation for the following half reaction occurring in acid solution:

V(s) HV2O73-

 

 

 

16. Balance the following redox reaction occurring in basic solution:

MnO4- + C2O42- MnO2 + CO2

 

 

 

17. 250.0 ml 0.200M MnO4- reacts with excess SO32-. How many grams of MnO2 are produced?

2MnO4- + 3SO32- +H2O → 2MnO2 +3SO42- + 2OH-

 

 

18. Determine the oxidation number for each bold atom.

MnO2

IO3-

Cr2O72-

C2O42-

Al(NO3)3

NH4Cl

NaH

 

 

 

 

 

 

 

HOOH

NO3-

H3PO4

Na2C2O4

I2

N2O3

Pt(H2O)42+

 

 

 

 

 

 

 

19. 250.0 mL of 0.500M MnO4- are required to titrate a 100.0 ml sample of SO3-2. Calculate the [SO3-2]

2MnO4- + 3SO32- +H2O → 2MnO2 + 3SO42-+ 2OH-

 

 

20. How is the breathalyzer reaction used to determine BAC? Write the reaction and describe how it works.

 

 

 

 

 

21. 2H+ + Mg Mg2+ + H2

Determine the Oxidizing agent__________ and the Reducing agent_________

22. Choose a suitable redox reactant to oxidize Cl- toClO4- in a redox titration.

 

23. Describe as an electrochemical or electrolytic cell:

a) Fuel cell

 

b) Charging a car battery

 

c) Discharging a car battery

 

d) Ni plating

 

e) Industrial Al production

 

f) Cl2 production

 

g) Electrowinning

 

24) Which of the reactants is gaining electrons? Which of the reactants is the oxidizing agent?

Br2 + SO2 + Na2SO4 + H2O → 2H2SO4 + 2NaBr

 

 

 

 

25) A student studied the following reactions and she recorded:

Pd2+ + Cu Pd + Cu2+ spontaneous

Pd2+ + Au no reaction

Pd2+ + Hg no reaction

Au3+ + Hg Au + Hg2+ spontaneous

List the oxidizing agents from strongest to weakest. List the reducing agents from strongest to weakest. Predict if the reaction will occur.

Au3+ + Cu

 

26) Match each type of electrolytic cell with the example cell.

Electrowinning

A silver anode oxidizes & Ag reduces on a Cu cathode

Electroplating

Pure Pb is reduced at the cathode while impure Pb oxidizes at the anode

Electrorefining

Pure Al is reduced at the cathode from molten bauxite (Al2O3).

27. List the anode, cathode, anode reaction , cathode reaction, and electrolyte for each commercial electrochemical cell.

Cell

anode

anode reaction

cathode

cathode reaction

electrolyte

Leclanche or Common Dry Cell

 

 

 

 

 

Alkaline Cell

 

 

 

 

 

Lead Storage or Car Battery

 

 

 

 

 

Fuel Cell

 

 

 

 

 

28. Which of the above cells requires continuous input of O2 and H2 and is produced by Ballard Industries.

 

 

29. List the anode, cathode, anode reaction, cathode reaction, and electrolyte for each commercial electrolytic cell.

Cell

anode

anode reaction

cathode

cathode reaction

electrolyte

Electrolysis of Molten Al2O3

 

 

 

 

 

Electrolysis of Aqueous NaCl

 

 

 

 

 

Silver-plating a Cu plating

 

 

 

 

 

Electrorefining pure Pb from impure Pb

 

 

 

 

 

30. Describe each term:

salt bridge

 

electrolyte

 

anode

 

cathode

 

spontaneous

 

electron affinity

 

cation

 

anion

 

electrochemical cell

 

electrolytic cell

 

oxidation number

 

electrolysis

 

oxidation

 

reduction

 

oxidizing agent

 

reducing agent

 

electrode

 

corrosion

 

electrowinning

 

electrorefining

 

over potential effect

 

fuel cell

 

31. Define corrosion of a metal, and illustrate your definition with reference to an example, using appropriate equations. Give TWO methods by which corrosion can be prevented and describe how each method works. The two methods must involve different chemical principles.

 

 

 

32. Which you would choose Zn or Cu to cathodically protect iron?

33. A2+ does not react with B, while C2+ reacts with B. Rank the oxidizing agents in decreasing order of strength. Rank the reducing agents in decreasing order of strength. Will A2+ react with C?

 

34. Write half reactions for each using the reduction table and list the half-cell potential.

 

Half Reaction

Eo

oxidation of water

 

 

oxidation of water in acid

 

 

reduction of water

 

 

reduction of water in alkaline

 

 

oxidation of H2 in water

 

 

oxidation of H2 in acid

 

 

oxidation of H2 in base

 

 

reduction of Cr2O72- in acid

 

 

reduction of HBr

 

 

 


35. Completely analyze the following electrochemical cell.

 

 

 

 

 

 

 

 

 

The anode reaction is:

 

The cathode reaction is:

 

The electrons flow from ___ to ___

 

The ions that migrate to the Zn electrode are:

 

The ions that migrate to the Cu electrode are:

 

The initial voltage of this cell is:

 

The voltage of this cell once equilibrium is reached is:

 

Describe the change in [Cu+2] in the Cu half cell

 

Describe the change in [NO3-1] in the Zn half cell

 

 


36. Completely analyze the following electrochemical cell.

 

 

 

 

 

 

 

 

 

 

The anode reaction is:

 

The cathode reaction is:

 

The electrons flow from ___ to ___

 

The ions that migrate to the Pt electrode are:

 

The ions that migrate to the Cu electrode are:

 

The intial voltage of this cell is:

 

The voltage of this cell once equilibrium is reached is:

 

Describe the change in [Cu+2] in the Cu half cell

 

Describe the change in [NO3-1] in the H+/H2 half cell

 

37. Completely analyze the following electrolytic cell.

 

 

 

 

 

 

 

 

 

 

 

 

 

Anode Reaction

 

Cathode Reaction

 

Chemicals produced at the anode

 

Chemicals produced at the cathode

 

The electrons flow from __to __

 

The chemical used to lower the mp is:

 

Which electrode is the anode ?

 

 

38. Completely analyze the following electrolytic cell. Note that the electrodes are not inert and because of that, the anode might oxidize.

 

 

 

 

 

 

 

 

 

 

 

 

 

Anode Reaction

 

Cathode Reaction

 

Chemicals produced at the anode

 

Chemicals produced at the cathode

 

The electrons flow from

 

The MTV

 

Which electrode is the anode ?

 

Electrochemistry Practice Test # 1

 

1. The following represents the process used to produce iron from iron III oxide:

Fe2O3 + 3CO → 2Fe + 3CO2 What is the reducing agent in this process?

 

A. Fe

B. CO

C. CO2

D. Fe2O3

 

2. Consider the following reaction: 2HNO2 + 2I- + 2H+ 2NO + I2 +2H2O

The oxidation number for each nitrogen atom

 

A. increases by 1

B. increases by 2

C. decreases by 1

D. decreases by 2

 

3. Which of the following reactions is spontaneous?

 

A. 2I- + Ag Ag+ + I2

B. Co2+ + Cu Co + Cu2+

C. Cu2+ + Pb → Pb2+ + Cu

D. Ni2+ + 2Ag 2Ag+ + Ni

 

4. Consider the following redox reaction for a lead-acid storage cell:

Pb + PbO2 + 4H+ + 2SO42- 2PbSO4 + 2H2O

The balanced, reduction half reaction is

 

A. Pb + SO42- 2PbSO4 + 2e-

B. Pb + 2H+ + SO42- PbSO4 + 2H2O + 2e-

C. PbO2 + 4H+ + SO42- + 2e- PbSO4 + 2H2O

D. PbO2 + 2SO42 + 2H2O + 2e- PbSO4 + 2OH-

 

5. Consider the following reaction: Cd2+(aq) + Zn(s) Cd(s) Zn2+(aq)

The potential for the reaction is +0.36 V. What is the reduction potential for the cadmium ion?

 

A. -1.12 V

B. -0.40 V

C. +0.40 V

D. +1.12 V

 

 

 

 

6. Which of the following involves a nonspontaneous redox reaction?

 

A. fuel cell

B. electroplating

C. redox titration

D. carbon dry cell

 

7. Consider the following redox reaction:

2MnO4- + 16H+ + 5Sn2+ → 2Mn2+ + 8H2O + 5Sn4+

In a redox titration, 0.60 mole of KMnO4 reacts completely with a solution of Sn(NO3)2. How many moles of Sn(NO3)2 were present in the solution?

A. 0.024 moles

B. 0.060 moles

C. 1.5 moles

D. 0.30 moles

 

8. Which of the following is not a redox reaction?

 

A. Cu + Br2 CuBr2

B. CO + H2O CO2 + H2

C. CH4 + H2O CO2 + 2H2O

D. NaOH + HCl NaCl + H2O

 

9. What is the minimum voltage required to form nickel from an aqueous solution of NiI2 using inert electrodes?

 

A. 0.26 V

B. 0.28 V

C. 0.54 V

D. 0.80 V

 

10. What substances are formed at the anode and cathode during electrolysis of molten sodium chloride?

 

Anode Cathode

 

A. O2 H2

B. Na Cl2

C. Cl2 H2

D. Cl2 Na

 

 

 

 

 

11. A solution containing an unknown cation reacts spontaneously with both zinc and copper. The unknown cation is

 

A. 1.0 M H+

B. 1.0 M Ag+

C. 1.0 M Sr2+

D. 1.0 M Mn2+

 

12. Which of the following half-reactions are balanced?

 

A. ClO- + H2O + e- Cl2 + 2OH-

B. 2ClO- + H2O + 2e- Cl2 + 3OH-

C. 2ClO- + 2H2O + 2e- Cl2 + 4OH-

D. 2ClO- + 2H2O Cl2 + 4OH- + 2e-

 

13. Which of the following is a spontaneous redox reaction?

 

A. Ag+ + I- AgI

B. Ag+ + Fe2+ Ag + Fe3+

C. 3Ag+ + Au 3Ag + Au3+

D. 2Ag+ + Ni2+ 2Ag + Ni

 

14. Salting the roads during the winter increases the amount of corrosion of cars. The is because the salt

 

A. reacts with the iron

B. provides an electrolyte

C. acts as a reducing agent

D. acts as an oxidizing agent

 


Consider the following electrochemical cell for the next five questions.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

15. The half-reaction that occurs at the anode is

 

A. Ni N2+ + 2e-

B. Ni2+ + 2e- Ni

C. Cu Cu2+ + 2e-

D. Cu2+ + 2e- Cu

 

16. The half-reaction that occurs at the cathode is

 

A. Ni N2+ + 2e-

B. Ni2+ + 2e- Ni

C. Cu Cu2+ + 2e-

D. Cu2+ + 2e- Cu

 

17. The cell potential or Eo is

 

A. 0.41 V

B. 0.78 V

C. 0.34 V

D. 0.60 V

 

18. The following ions migrate to the Cu electrode

 

A. K+ Cu2+ Ni2+

B. Cu2+ Ni2+

C. Cl- NO3-

D. Cl- NO3- 2e-

 

19. The electrons flow

 

A. through the salt bridge from Cu to Ni

B. through the salt bridge from Cu to Ni

C. through the wire from Cu to Ni

D. through the wire from Ni to Cu

 

20. Which of the following will not react spontaneously with 1.0 M HCl?

 

A. tin

B. lithium

C. mercury

D. magnesium

 

21. Which of the following can be produced by electrolysis from a 1.0 M aqueous solution containing its ion?

A. nickel

B. sodium

C. aluminum

D. magnesium

 

22. In order for an electrolytic cell to operate, it must have

 

A. a voltmeter.

B. a salt bridge.

C. a power supply.

D. an aqueous solution.

 

23. In the electrolysis of molten ZnCl2 using carbon electrodes, the reaction that occurs at the anode is

 

A. Zn Zn2+ + 2e-

B. Zn2+ + 2e- Zn

C. 2Cl- → Cl2 + 2e-

D. Cl2 + 2e- 2Cl-

 

24. In the electrolysis of molten zinc chloride, the half-reaction at the anode is

 

A. Cl2 + 2e- 2Cl-

B. 2Cl- Cl2 + 2e-

C. Zn2+ + 2e- Zn

D. Zn Zn2+ + 2e-

 

 

 

 

25. The corrosion of iron can be prevented by attaching a piece of

 

A. Mn

B. Cu

C. Pb

D. Sn

 

26. The oxidation number of carbon in CaC2O4 is

 

A. +2

B. +3

C. +4

D. +6

 

27. To plate a nickel coin with copper,

 

A. the nickel coin must be the cathode.

B. the cathode must be made out of copper

C. the electrons must flow to the anode

D. the solution must contain nickel ions

 

Consider the following electrochemical cell for the next five questions.

 

 

 

 

 

 

 

 

 

 

 

 

 

28. Which of the following statements apply to this electrochemical cell?

I Electrons flow through the wire toward the copper electrode.

II The copper electrode increases in mass.

III Anions move toward the Zn half-cell.

 

A. I and II only

B. I and III only

C. II and III only

D. I, II, and III

29. The balanced equation for the overall reaction is

 

A. Zn + Cu2+ Cu + Zn2+

B. Cu + Zn2+ Zn + Cu2+

C. Zn2+ + Cu Cu2+ + Zn

D. Cu + Zn Zn + Cu

 

30. At equilibrium the voltage of the above cell is

 

A. -1.10 V

B. 0.00 V

C. +0.42 V

D. +1.10 V

 

31. This redox reaction occurs because

 

A. Zn is a stronger oxidizing agent than Cu

B. Zn is a stronger reducing agent than Cu,

C. Cu is a stronger oxidizing agent than Zn

D. Zn2+ is a weaker reducing agent than Cu2+

 

32. The initial cell voltage at 25 oC is

 

A. -1.10 V

B. +1.10 V

C. +0.91 V

D. +0.86 V

 

33. Consider the following redox reaction: Co2+(aq) + 2Ag(s) 2Ag+(aq) + Co(s)

The reaction is

 

A. spontaneous and Eo is positive

B. spontaneous and Eo is negative

C. non-spontaneous and Eo is positive

D. non-spontaneous and Eo is negative

 

34. When MnO4- reacts to form Mn2+, the manganese in MnO4- is

 

A. reduced as its oxidation number increases

B. reduced as its oxidation number decreases

C. oxidized as its oxidation number increases

D. oxidized as its oxidation number decreases

 

 

 

 

35. The electrolyte used in the alkaline battery is

 

A. KCl

B. NaOH

C. H2SO4

D. KOH

 

36. The electrolyte used in an automobile battery is

 

A. KCl

B. NaOH

C. H2SO4

D. KOH

 

37. The anode used in the commercial production of Aluminum is

 

A. C

B. Pt

C. Al

D. Al2O3

 

38. The anode and cathode used in the electrorefining of impure lead to pure lead are

 

Anode Cathode

 

A. Pure Pb Impure Pb

B. Impure Pb Pure Pb

C. Pb2+ Pb

D. Pb Pb2+

 

39. The anode in the LeClanche or common dry cell is

 

A. C

B. Zn

C. Mg

D. KOH

 


40. Which of the following are electrolytic cells

 

I Electro winning

II Electroplating

III Charging a car battery

IV Fuel cell

 

A. I and II only

B. I, II, and III only

C. II and II only

D. I, II, III, and IV

 

Subjective

 

1. Balance the following in basic solution.

 

MnO4- + C2O42- MnO2 + CO2 (basic)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2. Consider the electrolysis of 1.0 M H2SO4 using platinum electrodes.

 

a) Write the oxidation half-reaction

 

 

 

b) Write the reduction half-reaction

 

 

 

c) Write the overall reaction and determine the minimum theoretical voltage required.

 

 

3. Consider the following diagram for the electro refining of lead.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

a) On the diagram, label the anode and cathode.

 

 

 

b) Write the formula for a suitable electrolyte

 

 

 

c) Write the equation for the reduction half-reaction.

 

 

 

4. Describe two chemically different methods that can be used to prevent corrosion of iron and explain why each method works.

 

Method 1:

 

Explanation:

 

 

Method 2:

 

Explanation:

 

5. The data below were obtained in a redox titration of a 25.00 mL sample containing Sn2+ ions using 0.125 M KMnO4 according to the following reaction:

2MnO4- + 16H+ + 5Sn2+ 2Mn2+ + 8H2O + 5Sn4+

  Calculate the [Sn2+]

Volume of KMnO4 used (mL)

Trial 1 Trial 2 Trial 3

 

Initial burette reading 2.00 13.80 24.55

Final burette reading 13.80 24.55 35.32

 

 

 

 

 

 

 

 

 

 

6. A student wanted to electroplate a coin with copper.

 

a) Identify a suitable anode

 

 

 

b) Identify an appropriate electrolyte

 

 

 

c) To with battery terminal (positive or negative) should the coin be connected?

 

 

 

7. Consider the electrolysis of molten magnesium chloride with Cu electrodes (Cu electrodes are not inert and can oxidize: Cl-, or Cu will oxidize)

 

a) Identify the product at the anode.

 

 

 

b) Write the equation for the reduction half-reaction.

 

 

c) Write the equation for the overall reaction.

 

 

 

8. Completely analyze the following electrochemical cell.

 

voltmeter

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Chemistry 12 Electrochemistry Practice Test 2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1. As the cell operates, the electrons flow from the nickel electrode to the palladium electrode. The reaction occurring at the anode is

 

A Pd Pd2+ + 2e-

B Ni Ni2+ + 2e-

C Pd2+ + 2e- Pb

D Ni2+ + 2e- Ni

 

2. As the cell operates,

 

A both the K+ and the NO3- migrate into the nickel half-cell

B both the K+ and the NO3- migrate into the palladium half-cell

C the K+ migrates into the nickel half-cell and the NO3- migrates into the palladium half-cell

D the K+ migrates into the palladium half-cell and the NO3- migrates into the nickel half-cell

 

3. The initial cell voltage is 1.21 V. The reduction potential of Pd2+ is

 

A -1.21 V

B -.95 V

C +0.95

D +1.21 V

 


4. What substances are formed at the anode and cathode during electrolysis of molten sodium chloride, NaCl(l)?

 

Anode Cathode

 

A O2 H2

B Na Cl2

C Cl2 H2

D Cl2 Na

 

5. Consider the following electrolytic cell:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

In the cell above

 

A I- migrates to the anode and gains electrons

B I- migrates to the cathode and loses electrons

C Na+ migrates to the anode and loses electrons

D Na+ migrates to the cathode and gains electrons

 

6. Which of the following are necessary for electroplating to occur using an electrolytic cell?

I Two electrodes

II A metal being reduced

III A direct current power supply

 

A I and II only

B I and III only

C II and III only

D I, II, and III

 

7. A fuel cell consumes H2 and O2 gas, uses a KOH electrolyte, and produces electricity. The reaction at the anode is

 

A 2H+ + 2e- H2

B 1/2O2 + 2H+ + 2e- H2O

C 4OH- O2 + 2H2O + 4e-

D H2 + 2OH- 2H2O + 2e-

 

8. A student investigating redox reactions recorded the following results:

V2+ + Te2- no reaction

U4+ + Te2- U3+ + Te

 

Based on these results, the strengths of the oxidizing agents, arranged from strongest to weakest, are

 

A V2+ Te U4+

B U4+ Te V2+

C U3+ Te2- V2+

D V2+ Te2- U3+

 

9. What is the minimum voltage required to form nickel from an aqueous solution of NiI2 using inert electrodes?

 

A 0.26 V

B 0.28 V

C 0.54 V

D 0.80 V

 


10.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Which of the following occurs as the cell operates?

 

A the Zn electrode is reduced and increases in mass

B the Zn electrode is reduced and decreases in mass

C the Zn electrode is oxidized and increases in mass

D the Zn electrode is oxidized and decreases in mass

 

 

11. Which of the following reactants would produce an E0 of +0.63 V?

 

A Ag+ + I2

B Pb2+ + Zn

C Mg2+ + Ca

D Zn2+ + Mn

 

12. The concentration of Fe2+(aq) can be determined by a redox titration using

 

A KBr

B SnCl2

C KMnO4 (basic)

D KBrO3 (acidic)

 

13. Which of the following will oxidize Fe2+?

 

A I2(s)

B Ni(s)

C Zn(s)

D Br2(l)

 


14. The oxidation number of carbon in C2O42- is

 

A +3

B +4

C +5

D +6

 

15. Consider the following reaction: 3As2O3 + 4NO3- + 7H2O → 6H3AsO4 + 4NO

 

The oxidizing agent is

 

A H+

B H2O

C NO3-

D AsO3

 

16. When W2O5 is converted to WO2 in a redox reaction, the W has been

 

A reduced since its oxidation number has increased

B reduced since its oxidation number has decreased

C oxidized since its oxidation number has increased

D oxidized since its oxidation number has decreased

 

17. Consider the following:

I Water

II Oxygen gas

III Nitrogen

 

At 25oC, a piece of iron rusts in the presence of

 

A I only

B III only

C I and II only

D II and III only

 

18. Which of the following represents a redox reaction?

 

A H2CO3 H2O + CO2

B CuS + H2 H2S + Cu

C AgNO3 + NaCl AgCl + NaNO3

D 2HCl + Na2SO3 2NaCl + H2SO3

 

 

 

 

19. The following reaction occurs in an electrochemical cell:

3Cu2+ + Cr → 2Cr3+ + 3Cu

The Eo for the cell is

 

A 0.40 V

B 0.75 V

C 1.08 V

D 2.50 V

 

20. During the corrosion of magnesium, the anode reaction is

 

A Mg Mg2+ + 2e-

B Mg2+ + 2e- Mg

C 4OH- O2 + 2H2O + 4e-

D O2 + 2H2O + 4e- 4OH-

 

21. A molten binary salt, ZnCl2, undergoes electrolysis. The cathode reaction is

 

A Zn Zn2+ + 2e-

B 2Cl- Cl2 + 2e-

C Cl2 + 2e- 2Cl-

D Zn2+ + 2e- Zn

 

22. Which of the following represents a redox reaction?

 

A CaCO3 CaO + CO2

B SiCl4 + 2Mg Si + 2MgCl2

C 2NaOH + H2SO4 2H2O + Na2SO4

D AgBr + 2S2O32- Ag(S2O3)23- + Br-

 

23. The process of applying an electric current through a cell to produce a chemical change is called

A corrosion

B ionization

C hydrolysis

D electrolysis

 


24. A student investigating redox reactions recorded the following results:

 

V2+ + Te2- no reaction

 

U4+ + Te2- U3+ + Te

 

Based on these results, the strengths of the oxidizing agents, arranged from strongest to weakest, are

 

A V2+ Te U4+

B U4+ Te V2+

C U3+ Te2- V2+

D V2+ Te2- U3+

 

25. A spontaneous redox reaction occurs when Sn2+ is mixed with

 

A I2

B Cu

C H2S

D Ag2S

 

26. Consider the redox reaction: 2BrO3- + 10Cl- + 12H+ Br2 + 5Cl2 + 6H2O

the oxidation half-reaction ivolved in this reaction is

 

A 2Cl- Cl2 + 2e-

B 2H+ H2 + 2e-

C BrO3- + 6H+ + 5e- Br2 + 3H2O

D BrO3- + 6H+ Br2 + 3H2O + 5e-

 

27. Which of the following is not a redox reaction?

 

A Cu + Br2 CuBr2

B CO + H2O CO2 + H2

C CH4 + O2 CO2 + 2H2O

D NaOH + HCl NaCl + H2O

 

28. During the electrolysis of 1.0 M Na2SO4, the reaction at the cathode is

 

A Na+ + 1e- Na

B 2SO42- S2O82- + 2e-

C 2H2O O2 + H+ + 4e-

D 2H2O + 2e- H2 + 2OH-

 

 

 

 

29. An oxidizing agent will cause which of the following changes?

 

A PtO2 PtO

B PtO3 PtO2

C Pt(OH)2 Pt

D Pt(OH)22+ PtO3

 

30. Consider the overall reaction of the nickel-cadmium battery:

NiO2(s) + Cd(s) + 2H2O(l) Ni(OH)2(s) + Cd(OH)2(s)

 

Which of the following occurs at the anode as the reaction proceeds?

 

A Cd loses 2e- and forms Cd(OH)2(s)

B Cd gains 2e- and forms Cd(OH)2(s)

C NiO2 loses 2e- and forms Ni(OH)2(s)

D NiO2 gains 2e- and forms Ni(OH)2(s)

 

31. Which of the following can be produced by the electrolysis from a 1.0 M aqueous solution containing its ions?

 

A nickel

B sodium

C aluminum

D magnesium

 

32. In the electrolysis of molten ZnCl2 using carbon electrodes, the reaction that occurs at the anode is

 

A Zn Zn2+ + 2e-

B Zn2+ + 2e- Zn

C 2Cl- Cl2 + 2e-

D Cl2 + 2e- 2Cl-

 

33. In order for the electrolytic cell to operate, it must have

 

A a voltmeter

B a salt bridge

C a power supply

D an aqueous solution

 

 


Subjective

 

1. a) Indicate in the blank spaces on the following chart whether or not a reaction will occur when the metals are added to the aqueous ions.

 

 

Pd Rh Pt

 

 

Pd2+

 

Rh2+ no reaction no reaction

 

Pt2+ reaction reaction

 

 

 

 

 

b) List the oxidizing agents in order of strongest to weakest

 

 

 

 

 

 

2. Consider the following reaction for the formation of rust:

Fe(s) + O2(g) + H2O(l) Fe(OH)2

 

Describe and explain two methods, using different chemical principles, to prevent the formation of rust.

 

a)

 

b)

 

 

3. Consider the following redox reaction:

 

H2Se + SO42- + 2H+ Se + H2SO3 + H2O

 

Calculate the Eo for the reaction.

 

 

 

4. Balance the following redox reaction in basic solution:

 

Au + Cl- + O2 AuCl4- + OH-

 

 

 

 

 

 

 

 

 

 

 

 

5. Draw and label a simple electrolytic cell capable of electroplating and inert electrode with silver.

 

 

 

 

 

 

 

 

 6.

 

a) During the production of magnesium metal from seawater, magnesium ions are first precipitated from seawater as magnesium hydroxide. The magnesium hydroxide is neutralized by hydrochloric acid, producing magnesium chloride. Write the neutralization reaction.

 

 

b) The salt produced, magnesium chloride, is dried melted and undergoes electrolysis. Write the reaction at each electrode.

 

Anode

 

Cathode

 

c) It is not possible to remove Mg from a 1.0 M solution. Explain why?

d) Write the anode reaction if Cu electrodes were used instead of C.

 

 

7. Consider the following diagram in the electro refining of lead:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

a) On the diagram above, label the anode and cathode.

 

 

b) Write the formula for a suitable electrolyte.

 

 

c) Write the equation for the reduction half-reaction.

 

 

d) Write the anode reaction