Chem 1412- Home-work 7
1.
How long will it take to produce 78 g of Al metal by the reduction of Al3+ in an electrolytic cell with
a current of 2.0 A?
A. 0.01 s
2.
B. 85,000 C
B. 8.6  104 F
E. 1.0  1012 s
C. 21,000 C
D. 42,500 C
E. 0.88 C
C. 0.90 F
D. 6.2  10 -3 F
E. 1.1 F
Determine the equilibrium constant (Keq) at 25C for the reaction
Cl2(g) + 2Br- (aq)
A. 1.5  10-10
5.
D. 116 h
How many faradays are transferred in an electrolytic cell when a current of 2.0 amperes flows for
12 hours?
A. 24 F
4.
C. 13 h
How many coulombs (C) of electrical charge must pass through an electrolytic cell to reduce 0.44
mol Ca2+ ion to calcium metal?
A. 190,000 C
3.
B. 420 s
B. 6.3  109
2Cl- (aq) + Br2(l)
C. 1.3  1041
D. 8.1  104
E. 9.8
Consider the following standard reduction potentials in acid solution:
The weakest reducing agent listed above is
A. Cr3+.
6.
B. Cr.
C. Mn2+.
D. Co.
E. MnO4-.
Consider the following standard reduction potentials in acid solution:
The strongest oxidizing agent among those shown above is
A. Fe3+.
7.
B. Fe2+.
C. Br-.
D. Al3+.
E. Al.
According to the following cell diagram, which chemical species undergoes reduction?
Sn | Sn2+ || NO3- (acid soln), NO(g) | Pt
A. Sn
B. Sn2+
C. NO3-
D. NO
E. Pt
8.
The overall reaction 2Co3+(aq) + 2Cl-(aq)  2Co2+(aq) + Cl2(g) has the standard cell voltage Ecell=
0.46 V. Given that Cl2(g) + 2e-  2Cl-(aq), E = 1.36 V,
calculate the standard reduction potential for the following the half reaction at 25C:
Co3+ + e-  Co2+
A. 1.82 V
9.
C. 0.90 V
D. -1.82 V
E. -1.36 V
Calculate Ecell for a silver-aluminum cell in which the cell reaction is
Al(s) + 3Ag+(aq)  Al3+(aq) + 3Ag(s)
A. -2.46 V
10.
B. -0.90 V
B. 0.86 V
C. -0.86 V
D. 2.46 V
E. none of these
Complete and balance the following redox equation. What is the coefficient of H2O when the
equation is balanced with the set of smallest whole-number coefficients?
H2O +MnO4- + I- MnO2 + IO3- (basic solution)
A. 1
B. 2
C. 4
D. 10
E. none of these
11. Complete and balance the following redox equation.
Br2  BrO3- + Br- (basic solution)
The sum of the smallest whole-number coefficients is
A. 9.
B. 12.
C. 18.
D. 21.
E. none of these.
12. Given the following notation for an electrochemical cell
Pt(s) | H2(g) | H+(aq) || Ag+(aq) | Ag(s),
what is the balanced overall (net) cell reaction?
A. 2H+(aq) + 2Ag+(aq)  H2(g) + 2Ag(s)
B. H2(g) + 2Ag(s)  H+(aq) + 2Ag+(aq)
C. 2H+(aq) + 2Ag(s)  H2(g) + 2Ag+(aq)
D. H2(g) + Ag+(aq)  H+(aq) + Ag(s)
E. H2(g) + 2Ag+(aq)  2H+(aq) + 2Ag(s)
13. Consider an electrochemical cell constructed from the following half cells, linked by an
external circuit and by a KCl salt bridge.
 an Al(s) electrode in 1.0 M Al(NO3)3 solution
 a Pb(s) electrode in 1.0 M Pb(NO3)2 solution
The balanced overall (net) cell reaction is
A. Pb(s) + Al3+(aq)  Pb2+(aq) + Al(s).
B. 3Pb(s) + 2Al3+(aq)  3Pb2+(aq) + 2Al(s).
C. 3Pb2+(aq) + 2Al(s)  3Pb(s) + 2Al3+(aq).
D. Pb2+(aq) + Al(s)  Pb(s) + Al3+(aq).
14. Consider the following standard reduction potentials in acid solution:
The strongest reducing agent listed above is
A. Cr3+.
B. Cr.
C. Mn2+.
D. Co.
E. E.MnO4-.
15. For the reaction, 2Cr2+ + Cl2(g)  2Cr3+ + 2Cl-, Ecell is 1.78 V. Calculate Ecell for the
related reaction Cr3+ + Cl-  Cr2+ + (1/2)Cl2(g).
A. 1.78 V
B. 0.89 V
C. -1.78 V
D. -0.89 V
E. none of these
16. In the following half equation, which is the oxidizing agent?
NO3-(aq) + 4H+(aq) + 3e-  NO(g) + 2H2O
A. NO3B. H+
C. eD. NO
E. H2O
2+
17. Given the standard reduction potentials for the following half-reactions, Pb /Pb = -0.13 V
2+
and Ni /Ni = -0.28 V; which substance would be oxidized in a voltaic cell?
2+
+
2+
(A) Pb
(B) H
(C) Ni
(D) Pb
(E) Ni
18. Calculate K, the equilibrium constant for the reaction, Ag+ (aq) + Fe2+(aq) → Ag(s) + Fe3+
(A) 10.0
(B) 2.0
(C) 3.2
(D) 1.0
19. Using the following half-reactions, select the strongest reducing agent:
-
-
HgO + H2O + 2e → Hg + 2 OH E° = -0.0977 V
-
-
Zn(OH) 2 + 2e → Zn + 2 OH E° = -1.25 V
-
-
Ag O + H O + 2e → Ag + 2 OH E° = 0.342 V
2
2
+
-
-
B(OH) 3 + 7 H + 9e → BH4 + 3 H2O E° = -0.481 V
(A) Hg
(B) Zn
(C) Ag
(D) BH4
20. What is the E0 value for a cadmium–silver voltaic cell?
(A) 0.6 V
(B) 2.0 V
(C) 1.2 V
(D) 0.40 V
-