1.How many electrons are transferred in the following reaction when it is balanced in acidic solution? SO32–(aq) + MnO4–(aq) SO42–(aq) + Mn2+(aq)
a)6
b)2
c)10
d)5
e)3
2.Which energy conversion shown below takes place in a galvanic cell?
a)electrical to chemical
b)chemical to electrical
c)mechanical to chemical
d)chemical to mechanical
e)mechanical to electrical
3.Which of the following reactions is possible at the anode of a galvanic cell?
a)Zn Zn2+ + 2e–
b)Zn2+ + 2e– Zn
c)Zn2+ + Cu Zn + Cu2+
d)Zn + Cu2+ Zn2+ + Cu
e)two of these
4.Which of the following is true for the cell shown here? Zn(s)│Zn2+(aq) ║ Cr3+(aq) │Cr(s)
a)The electrons flow from the cathode to the anode.
b)The electrons flow from the zinc to the chromium.
c)The electrons flow from the chromium to the zinc.
d)The chromium is oxidized.
e)The zinc is reduced.
5.The anode in a voltaic cell and in an electrolytic cell is
a)positive in both cells
b)the site of oxidation and of reduction, respectively
c)the site of reduction and of oxidation, respectively
d)the site of oxidation in both cells
e)the site of reduction in both cells
6.Which statement is always true of the cathode in an electrochemical cell?
a)It is considered the “negative” electrode.
b)It is considered the “positive” electrode.
c)Reduction occurs here.
d)Metal is plated out here.
e)Negative ions flow toward the cathode.
7.A strip of copper is placed in a 1 M solution of copper nitrate and a strip of silver is placed in a 1 M solution of silver nitrate. The two metal strips are connected to a voltmeter by wires and a salt bridge connects the solutions. The following standard reduction potentials apply:
Ag+(aq) + e– Ag(s) / ℰ° = +0.80 VCu2+(aq) + 2e– Cu(s) / ℰ° = +0.34 V
Which of the following statements is false?
a)Electrons flow in the external circuit from the copper electrode to the silver electrode.
b)The silver electrode increases in mass as the cell operates.
c)There is a net general movement of silver ions through the salt bridge to the copper half-cell.
d)Negative ions pass through the salt bridge from the silver half-cell to the copper half-cell.
e)Some positive copper ions pass through the salt bridge from the copper half-cell to the silver half-cell.
8.You are told that metal X is a better reducing agent than metal Y. This must mean that:
a)X+ is a better oxidizing agent than Y+.
b)X+ is a better reducing agent than Y+.
c)Y is a better oxidizing agent than X.
d)Y+ is a better reducing agent than X+.
e)Y+ is a better oxidizing agent than X+.
9.Which of the following species cannot function as an oxidizing agent?
a)S(s)
b)NO3–(aq)
c)Cr2O72–(aq)
d)I–(aq)
e)MnO4–(aq)
10.Which of the following is the strongest oxidizing agent?
MnO4– + 4H+ + 3e– MnO2 + 2H2O / ℰ° = 1.68 VI2 + 2e– 2I– / ℰ° = 0.54 V
Zn2+ + 2e– Zn / ℰ° = –0.76 V
a)MnO4–
b)I2
c)Zn2+
d)Zn
e)MnO2
12.Which metal, Al or Ni could reduce Zn2+ to Zn(s) if placed in a Zn2+(aq) solution?
Zn2+ + 2e– Zn / ℰ° = –0.76 VAl3+ + 3e– Al / ℰ° = –1.66 V
Ni2+ + 2e– Ni / ℰ° = –0.23 V
a)Al
b)Ni
c)Both Al and Ni would work.
d)Neither Al nor Ni would work.
e)Cannot be determined.
13.Which of the following is the best reducing agent?
Cl2 + 2e– 2Cl– / ℰ° = 1.36 VMg2+ + 2e– Mg / ℰ° = –2.37 V
2H+ + 2e– H2 / ℰ° = 0.00 V
a)Cl2
b)H2
c)Mg
d)Mg2+
e)Cl-
14.Consider the galvanic cell shown below (the contents of each half-cell are written beneath each compartment):
0.50 M Br2 0.20 M Cr3+
0.10 M Br–
The standard reduction potentials are as follows:
Cr3+(aq) + 3e– Cr(s)ℰ°= –0.725 V
Br2(aq) + 2e– 2Br–(aq)ℰ°= +1.090 V
What is ℰ°for this cell?
a)1.815 V
b)0.365 V
c)–0.365 V
d)4.720 V
e)1.320 V
15.Consider the galvanic cell shown below (the contents of each half-cell are written beneath each compartment):
0.50 M Br2 0.20 M Cr3+
0.10 M Br–
The standard reduction potentials are as follows:
Cr3+(aq) + 3e– Cr(s)ℰ° = -0.73 V
Br2(aq) + 2e– 2Br–(aq) ℰ° = +1.09 V
Which of the following statements about this cell is false?
a)This is a galvanic cell.
b)Electrons flow from the Pt electrode to the Cr electrode.
c)Reduction occurs at the Pt electrode.
d)The cell is not at standard conditions.
e)To complete the circuit, cations migrate into the left half-cell and anions migrate into the right half-cell from the salt bridge.
16.Refer to the galvanic cell below (the contents of each half-cell are written beneath each compartment):
0.10 M MnO4– 0.40 M Cr3+
0.20 M Mn2+ 0.30 M Cr2O72–
0.010 M H+ 0.010 M H+
The standard reduction potentials are as follows:
MnO4– + 8H+ + 5e– Mn2+ + 4H2O, ℰ° = 1.507 V
Cr2O72– + 14H+ + 6e– 2Cr3+ + 7H2O, ℰ° = 1.330 V
What is the value of ℰ°cell?
a)–0.177
b)2.837
c)0.177
d)0.677
e)6.205
Use the following to answer questions 17-18:
Refer to the galvanic cell below (the contents of each half-cell are written beneath each compartment):
0.10 M MnO4– 0.40 M Cr3+
0.20 M Mn2+ 0.30 M Cr2O72–
0.010 M H+ 0.010 M H+
The standard reduction potentials are as follows:
MnO4– + 8H+ + 5e– Mn2+ + 4H2O, ℰ° = 1.51 V
Cr2O72– + 14H+ + 6e– 2Cr3+ + 7H2O, ℰ° = 1.33 V
17.When current is allowed to flow, which species is oxidized?
a)Cr2O72–
b)Cr3+
c)MnO4–
d)Mn2+
e)H+
18.When current is allowed to flow, which species is reduced?
a)Cr2O72–
b)Cr3+
c)MnO4–
d)Mn2+
e)H+
19.The galvanic cell described by Zn(s)│Zn2+(aq)║Cu2+(aq)│Cu(s) has a standard cell potential of 1.101 volts. Given that Zn(s) Zn2+(aq) + 2e– has an oxidation potential of 0.762 volts, determine the reduction potential for .
a)1.863 V
b)–1.863 V
c)–0.339 V
d)0.339 V
e)none of these
20.The following question refers to a galvanic cell that utilizes the following reaction (unbalanced):
(AuCl4)–(aq) + Cu(s) Au(s) + Cl–(aq) + Cu2+(aq)
Given the following information, determine the standard cell potential:
Species / Standard Reduction Potential (V)Au3+(aq) / 1.4980
Cu2+(aq) / -0.3391
a)1.1589 V
b)1.8371 V
c)3.8158 V
d)0.8198 V
e)4.1549 V
21.Choose the correct statement given the following information:
Fe3+(aq) + e– Fe2+(aq) ℰ° = 0.77 V
Fe(CN)63–(aq) + e– Fe(CN)64–(aq) ℰ° = 0.36 V
a)Fe2+(aq) is more likely to be oxidized than Fe2+complexed to CN–.
b)Fe3+(aq) is more likely to be reduced than Fe3+complexed to CN–.
c)Both A and B are true.
d)Complexation of Fe ions with CN– has no effect on their tendencies to become oxidized or reduced.
e)None of these is true.
22.The following question refers to the following system:
3Ag(s) + NO3–(aq) + 4H+(aq) 3Ag+(aq) + NO(g) + 2H2O(l)
Anode reaction:Ag Ag+(aq) + e–ℰ° = –0.7990 V
Cathode reaction:NO3–(aq) + 4H+(aq) + 3e– NO(g) + 2H2O(l)ℰ° = 0.9639 V
Determine the standard cell potential.
a)–1.7629 V
b)0.1649 V
c)2.0927 V
d)3.5258 V
e)0.5876 V
23.Which of the following would be the best oxidizing agent?
a)Cl2
b)Fe
c)Na
d)Na+
e)F–
24.Copper will spontaneously reduce which of the following?
a)Fe2+ and Ag+
b)Fe2+
c)Ag+
d)Al3+
e)Fe2+ and Al3+
25.Determine the standard potential, ℰ°, of a cell that employs the reaction:
Fe + Cu2+ Cu + Fe2+.
Reaction / ℰ° (volts)Fe2+ / + / 2e– / / Fe / –0.440
Cu2+ / + / 2e– / / Cu / +0.340
a)–0.100
b)–0.780
c)0.100
d)0.780
e)–0.200
Use the following to answer questions 26-27:
You make a cell with an aluminum electrode in a solution of aluminum nitrate and a zinc electrode in a solution of zinc nitrate.
26.If you could increase the concentration of Zn2+, which of the following is true about the cell potential?
a)It would increase.
b)It would decrease.
c)It would remain constant.
d)Cannot be determined.
e)None of these (A-D).
27.If you could increase the concentration of Al3+, which of the following is true about the cell potential?
a)It would increase.
b)It would decrease.
c)It would remain constant.
d)Cannot be determined.
e)None of these (A-D).
28.A concentration cell is constructed using two metal (M) electrodes with M2+ concentrations of 0.10 M and 1.00 10–5M in the two half-cells. Determine the reduction potential of M2+ given that the potential of the cell at 25°C is 0.118 V.
a)0 V
b)+0.118 V
c)–0.118 V
d)Cannot be determined with the information given.
e)None of the above.
29.What is ℰ of the following cell reaction at 25°C? ℰ°cell = 0.460 V.
Cu(s) | Cu2+(0.017 M) || Ag+(0.17 M) | Ag(s)
a)0.282 V
b)0.476 V
c)0.460 V
d)0.467 V
e)0.490 V
30.For the cell Cu(s) | Cu2+ || Ag+ | Ag(s), the standard cell potential is 0.46 V. A cell using these reagents was made, and the observed potential was 0.30 V at 25oC. What is a possible explanation for the observed voltage?
a)The Ag+ concentration was larger than the Cu2+ concentration.
b)The Cu2+ concentration was larger than the Ag+ concentration.
c)The Ag electrode was twice as large as the Cu electrode.
d)The volume of the Cu2+ solution was larger than the volume of the Ag+ solution.
e)The volume of the Ag+ solution was larger than the volume of the Cu2+ solution.