1. University of Kentucky
Clicker Questions
Chapter 18
Electrochemistry
Allison Soult
University of Kentucky

2. Fe2+ (aq) + MnO4– (aq) → Fe3+ (aq) + Mn2+ (aq)
What is the coefficient of Fe2+ when the following redox equation is balanced?
Fe2+ (aq) + MnO4– (aq) → Fe3+ (aq) + Mn2+ (aq) 1 2 3 4 5
Answer: e

3. Fe2+ (aq) + MnO4– (aq) → Fe3+ (aq) + Mn2+ (aq)
What is the coefficient of Fe2+ when the following redox equation is balanced?
Fe2+ (aq) + MnO4– (aq) → Fe3+ (aq) + Mn2+ (aq) 1 2 3 4 5
Answer: e

4. The following reaction occurs in a lead storage battery
The following reaction occurs in a lead storage battery. How many moles of electrons are transferred in the following balanced redox equation per reaction cycle?
Pb (s) + PbO2 (aq) + 2 HSO4– (aq) + 2 H+ (aq) → 2 PbSO4 (s) + 2 H2O (l)
2.34
1.35
1.30
2.41
Answer: b

5. The following reaction occurs in a lead storage battery
The following reaction occurs in a lead storage battery. How many moles of electrons are transferred in the following balanced redox equation per reaction cycle?
Pb (s) + PbO2 (aq) + 2 HSO4– (aq) + 2 H+ (aq) → 2 PbSO4 (s) + 2 H2O (l)
2.34
1.35
1.30
2.41
Answer: b

6. How many water molecules will there be when MnO4– + CN–  MnO2 + CNO–
is balanced in base?
4 on the reactant side
4 on the product side
2 on the reactant side
2 on the product side
Answer: c

7. How many water molecules will there be when MnO4– + CN–  MnO2 + CNO–
is balanced in base?
4 on the reactant side
4 on the product side
2 on the reactant side
2 on the product side
Answer: c

8. All of the above would function as cathodes.
Which transformation could take place at the anode of an electrochemical cell?
NO → NO3–
VO2+ → VO2+
O2 → H2O2
All of the above would function as cathodes.
All of the above would function as anodes.
Answer: a

9. All of the above would function as cathodes.
Which transformation could take place at the anode of an electrochemical cell?
NO → NO3–
VO2+ → VO2+
O2 → H2O2
All of the above would function as cathodes.
All of the above would function as anodes.
Answer: a

10. The purpose of the salt bridge in an electrochemical cell is
to maintain electrical neutrality in the half-cells via migration of ions.
to provide a source of ions to react at the anode and cathode.
to provide oxygen to facilitate oxidation at the anode.
to provide a means for electrons to travel from the anode to the cathode.
to provide a means for electrons to travel from the cathode to the anode.
Answer: a

11. The purpose of the salt bridge in an electrochemical cell is
to maintain electrical neutrality in the half-cells via migration of ions.
to provide a source of ions to react at the anode and cathode.
to provide oxygen to facilitate oxidation at the anode.
to provide a means for electrons to travel from the anode to the cathode.
to provide a means for electrons to travel from the cathode to the anode.
Answer: a

12. Ni (s) | Ni2+ (aq) || Ag+ (aq) | Ag (s)
What is the reducing agent in the following electrochemical cell?
Ni (s) | Ni2+ (aq) || Ag+ (aq) | Ag (s) Ni
Ni2+ Ag
Ag+
There is no reducing agent in an electrochemical cell.
Answer: a

13. Ni (s) | Ni2+ (aq) || Ag+ (aq) | Ag (s)
What is the reducing agent in the following electrochemical cell?
Ni (s) | Ni2+ (aq) || Ag+ (aq) | Ag (s) Ni
Ni2+ Ag
Ag+
There is no reducing agent in an electrochemical cell.
Answer: a

14. Ni2+ (aq) + 2 e– → Ni (s) –0.23 V Zn2+ (aq) + 2 e– → Zn (s) –0.76 V
Which of the following is the best reducing agent?
Ni2+ Ni Zn Ag
Ni2+ (aq) + 2 e– → Ni (s) –0.23 V
Zn2+ (aq) + 2 e– → Zn (s) –0.76 V
Ag+ (aq) + e– → Ag (s) 0.80 V
Answer: c

15. Ni2+ (aq) + 2 e– → Ni (s) –0.23 V Zn2+ (aq) + 2 e– → Zn (s) –0.76 V
Which of the following is the best reducing agent?
Ni2+ Ni Zn Ag
Ni2+ (aq) + 2 e– → Ni (s) –0.23 V
Zn2+ (aq) + 2 e– → Zn (s) –0.76 V
Ag+ (aq) + e– → Ag (s) 0.80 V
Answer: c

16. Mg (s) + Cu2+ (aq) → Cu (s) + Mg2+ (aq)
Calculate the cell potential for the following reaction under standard conditions:
Mg (s) + Cu2+ (aq) → Cu (s) + Mg2+ (aq)
+2.04
–2.04
+2.71
–1.36
+1.36
Cu2+ (aq) + 2 e– → Cu (s) 0.34 V
Mg2+ (aq) + 2 e– → Mg (s) –2.37 V
Answer: c

17. Mg (s) + Cu2+ (aq) → Cu (s) + Mg2+ (aq)
Calculate the cell potential for the following reaction under standard conditions:
Mg (s) + Cu2+ (aq) → Cu (s) + Mg2+ (aq)
+2.04
–2.04
+2.71
–1.36
+1.36
Cu2+ (aq) + 2 e– → Cu (s) 0.34 V
Mg2+ (aq) + 2 e– → Mg (s) –2.37 V
Answer: c

18. Which of the following metals will dissolve in nitric acid but not in hydrochloric acid?Au Ag Fe Pb Ni
Answer: b

19. Which of the following metals will dissolve in nitric acid but not in hydrochloric acid?Au Ag Fe Pb Ni
Answer: b

20. 2 Al (s) + 3 I2 (s) → 2 Al3+ (aq) + 6 I– (aq)
Consider a cell that employs the following overall reaction:
What is ΔG° for the cell?
2 Al (s) I2 (s) → 2 Al3+ (aq) I– (aq)
I2 (s) + 2 e– → 2 I– (aq) 0.54
Al3+ (aq) + 3 e– → Al (s) –1.66
636 kJ/mol
–648 kJ/mol
–216 kJ/mol
–636 kJ/mol
–1270 kJ/mol
Answer: e

21. 2 Al (s) + 3 I2 (s) → 2 Al3+ (aq) + 6 I– (aq)
Consider a cell that employs the following overall reaction:
What is ΔG° for the cell?
2 Al (s) I2 (s) → 2 Al3+ (aq) I– (aq)
I2 (s) + 2 e– → 2 I– (aq) 0.54
Al3+ (aq) + 3 e– → Al (s) –1.66
636 kJ/mol
–648 kJ/mol
–216 kJ/mol
–636 kJ/mol
–1270 kJ/mol
Answer: e

22. What is the value of the equilibrium constant when the cell potential is found to be −0.29 V for a transfer of 2 moles of electrons?
1.6 × 10–10
0.56
0.72
0.87
6.4 × 10–2
Answer: a

23. What is the value of the equilibrium constant when the cell potential is found to be −0.29 V for a transfer of 2 moles of electrons?
1.6 × 10–10
0.56
0.72
0.87
6.4 × 10–2
Answer: a

24. Calculate the cell potential (Ecell) of an electrochemical cell at 298 K with Mg/Mg2+ and Fe/Fe2+ electrodes. [Mg2+] = M and [Fe2+] = M.
Fe2+ (aq) + 2 e– → Fe (s) –0.45
Mg2+ (aq) + 2 e– → Mg (s) –2.37
1.90
1.92
1.94
2.82
2.80
Answer: a

25. Calculate the cell potential (Ecell) of an electrochemical cell at 298 K with Mg/Mg2+ and Fe/Fe2+ electrodes. [Mg2+] = M and [Fe2+] = M.
Fe2+ (aq) + 2 e– → Fe (s) –0.45
Mg2+ (aq) + 2 e– → Mg (s) –2.37
1.90
1.92
1.94
2.82
2.80
Answer: a

26. A concentration cell is assembled with a copper anode and cathode
A concentration cell is assembled with a copper anode and cathode. One cell has [Cu2+] = 0.25 M and the other has [Cu2+] = 2.5 M. What is the cell potential?
0 V
−0.030 V
0.030 V
− V V
Answer: c

27. A concentration cell is assembled with a copper anode and cathode
A concentration cell is assembled with a copper anode and cathode. One cell has [Cu2+] = 0.25 M and the other has [Cu2+] = 2.5 M. What is the cell potential?
0 V
−0.030 V
0.030 V
− V V
Answer: c

28. What mass of nickel can be plated from a solution containing Ni2+ with a current of 3.6 A for 14 minutes?
0.92 g
1.8 g
3.7 g
1.0 g
0.071 g
Answer: a

29. What mass of nickel can be plated from a solution containing Ni2+ with a current of 3.6 A for 14 minutes?
0.92 g
1.8 g
3.7 g
1.0 g
0.071 g
Answer: a

30. Au3+ (aq) + 3 e– → Au (s) 1.50 V Cu2+ (aq) + 2 e– → Cu (s) 0.34 V
Which of the following is the best sacrificial electrode for iron?
Au3+ (aq) + 3 e– → Au (s) 1.50 V Au Cu Ni Pb Mg
Cu2+ (aq) + 2 e– → Cu (s) 0.34 V
Fe3+ (aq) + 3 e– → Fe (s) –0.036 V
Pb2+ (aq) + 2 e– → Pb (s) –0.13 V
Answer: e
Ni2+ (aq) + 2 e– → Ni (s) –0.23 V
Mg2+ (aq) + 2 e– → Mg (s) –2.37 V

31. Au3+ (aq) + 3 e– → Au (s) 1.50 V Cu2+ (aq) + 2 e– → Cu (s) 0.34 V
Which of the following is the best sacrificial electrode for iron?
Au3+ (aq) + 3 e– → Au (s) 1.50 V Au Cu Ni Pb Mg
Cu2+ (aq) + 2 e– → Cu (s) 0.34 V
Fe3+ (aq) + 3 e– → Fe (s) –0.036 V
Pb2+ (aq) + 2 e– → Pb (s) –0.13 V
Answer: e
Ni2+ (aq) + 2 e– → Ni (s) –0.23 V
Mg2+ (aq) + 2 e– → Mg (s) –2.37 V