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⁺ + 2SO₄^2- → 2PbSO₄ + 2H₂O

The balanced, reduction half reaction is

A. Pb + SO₄^2- → 2PbSO₄ + 2e^-

B. Pb + 2H⁺ + SO₄^2- → PbSO₄ + 2H₂O + 2e^-

C. PbO₂ + 4H⁺ + SO₄^2- + 2e^- → 2PbSO₄ + 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. N_a 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 E^o 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 aqueous 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. Cu²⁺ + Zn → Zn²⁺ + 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. Zn²⁺ is a stronger oxidizing agent than Cu²⁺

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 E^o is positive

B. spontaneous and E^o is negative

C. non-spontaneous and E^o is positive

D. non-spontaneous and E^o 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 Electrowinning

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^- + C₂O₄^2- → MnO₂ + CO₂ (basic)

2(MnO₄^- + 4H⁺ + 3e^- → MnO₂ + 2H₂O )

3(C₂O₄^2- → 2CO₂ + 2e^-)

Acid: 2MnO₄^- + 3C₂O₄^2- + 8H⁺ → 2MnO₂ + 6CO₂ + 4H₂O

Basic: 2MnO₄^- + 3C₂O₄^2- + 4H₂O → 2MnO₂ + 6CO₂ + 8OH^-

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

a) Write the oxidation half-reaction

H₂O → 1/2O₂ + 2H⁺ + 2e^- E^o = -0.82 V

b) Write the reduction half-reaction

2H⁺ + 2e^- → H₂ E^o =   0.00 V

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

H₂O → 1/2O₂ + H₂          E^o = -0.82 V

MTV = +0.82 V

3. Consider the following diagram for the electrorefinning of lead.

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

b) Write the formula for a suitable electrolyte

Pb(NO₃)₂

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

Pb²⁺ + 2e^- → Pb_(s)

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

Method 1: Painting

Explanation: Prevents reactants H₂O and O₂ from contacting the iron

Method 2: Attach some Zn

Explanation: Fe is forced to be the cathode and cannot oxidize

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⁺

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

11.80 10.75 10.77 Average last two to get 10.76 mL

Calculate the [Sn²⁺]

[Sn²⁺] = 0.01076 L x 0.125 mole x 5 moles Sn²⁺

1 L 2 moles MnO₄^-

0.0250 L

= 0.135 M

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

a) Identify a suitable anode Cu

b) Identify an appropriate electrolyte CuSO₄

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

Negative

7. Consider the electrolysis of molten magnesium chloride.

a) Identify the product at the anode.

Cu²⁺

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

Mg²⁺ + 2e^- ® Mg_(s)

c) Write the equation for the overall reaction.

                                        Mg²⁺   +          Cu ®    Mg_(s)       +          Cu²⁺

8. Consider the following electrochemical cell.

Cathode Anode

a) Write the anode reaction

Mn ® Mn²⁺ + 2e^-

b) Write the cathode reaction

Sn²⁺ + 2e^- ® Sn

c) Write the overall reaction and determine the initial cell potential (E^o).

Sn²⁺ + Mn ® Mn²⁺ + Sn

d) Explain in words how the electrons move through the cell.

From anode Mn to cathode Sn

e) List all of the ions that migrate toward the Sn electrode.

Sn²⁺ Mn²⁺ K⁺

f) Which electrode loses mass?

Anode Sn

g) What is the purpose of the salt bridge?

To allow cations and anions to flow from one half cell to the other

h) What is the cell potential once equilibrium is achieved?

0.00 v