Prince George's Community College
CHM 1020 (Mr. Shah)
Electrochemistry
Fall 2013
Part I Multiple Choices: Select the best answer and circle it. (100 points)
1. Which one of the following is not a redox reaction?
A.
B.
C.
D.
E.
Al(OH)4-(aq) + 4H+(aq)  Al3+(aq) + 4H2O(l)
C6H12O6(s) + 6O2(g)  6CO2(g) + 6H2O(l)
Na6FeCl8(s) + 2Na(l)  8NaCl(s) + Fe(s)
2H2O2(aq)  2H2O(l) + O2(g)
CO2(g) + H2(g)  CO(g) + H2O(g)
2. Consider the reaction
CuO(s) + H2(g)  Cu(s) + H2O(l)
In this reaction, which substances are the oxidant and reductant,
respectively?
A.
B.
C.
D.
E.
CuO and H2
H2 and CuO
CuO and Cu
H2O and H2
None of these choices is correct.
1
3. Consider the following balanced redox reaction
Mn2+(aq) + S2O82-(aq) + 2H2O(l)  MnO2(s) + 4H+(aq) + 2SO42-(aq)
Which of the following statements is true?
A.
B.
C.
D.
E.
Mn2+(aq) is the oxidizing agent and is reduced.
Mn2+(aq) is the oxidizing agent and is oxidized.
Mn2+(aq) is the reducing agent and is oxidized.
Mn2+(aq) is the reducing agent and is reduced.
Manganese does not change its oxidation number in this reaction.
4. Consider the following balanced redox reaction
3CuO(s) + 2NH3(aq)  N2(g) + 3H2O(l) + 3Cu(s)
Which of the following statements is true?
A.
B.
C.
D.
E.
CuO(s) is the oxidizing agent and copper is reduced.
CuO(s) is the oxidizing agent and copper is oxidized.
CuO(s) is the reducing agent and copper is oxidized.
CuO(s) is the reducing agent and copper is reduced.
CuO(s) is the oxidizing agent and N2(g) is the reducing agent.
5. When the following redox equation is balanced with smallest whole
number coefficients, the coefficient for nitrogen dioxide will be _____.
I2(s) + HNO3(aq)  HIO3(aq) + NO2(g) + H2O(l)
A.
B.
C.
D.
E.
1
2
4
10
None of these choices is correct.
2
6. When the following redox equation is balanced with smallest whole
number coefficients, the coefficient for the hydrogen sulfate ion will
be ______.
Al(s) + HSO4-(aq) + OH-(aq)  Al2O3(s) + S2-(aq) + H2O(l)
A.
B.
C.
D.
E.
1
3
4
8
None of these choices is correct.
7. When the following redox equation is balanced with smallest whole
number coefficients, the coefficient for zinc will be _____.
Zn(s) + ReO4-(aq)  Re(s) + Zn2+(aq) (acidic solution)
A.
B.
C.
D.
E.
2
7
8
16
None of these choices is correct.
8. When the following redox equation is balanced with smallest whole
number coefficients, the coefficient for the iodide ion will be _____.
I-(aq) + NO3-(aq)  NO(g) + I2(s) (acidic solution)
A.
B.
C.
D.
E.
2
3
6
8
None of these choices is correct.
3
9. When the following redox equation is balanced with smallest whole
number coefficients, the coefficient for Sn(OH)3- will be _____.
Bi(OH)3(s) + Sn(OH)3-(aq)  Sn(OH)62-(aq) + Bi(s) (basic solution)
A.
B.
C.
D.
E.
1
2
3
6
None of these choices is correct.
10.Consider the following redox equation
Mn(OH)2(s) + MnO4-(aq)  MnO42-(aq) (basic solution)
When the equation is balanced with smallest whole number
coefficients, what is the coefficient for OH-(aq) and on which side of
the equation is OH-(aq) present?
A.
B.
C.
D.
E.
4, reactant side
4, product side
6, reactant side
6, product side
None of these choices is correct.
11.Which of the following statements about voltaic and electrolytic cells
is correct?
A. The electrons in the external wire flow from cathode to anode in
both types of cell.
B. Oxidation occurs at the cathode only in a voltaic cell.
C. The free energy change, G, is negative for an electrolytic cell.
D. The cathode is labeled as positive (+) in a voltaic cell but negative
(-) in an electrolytic cell.
E. Reduction occurs at the anode in an electrolytic cell.
4
12.Which of the following statements about voltaic and electrolytic cells
is correct?
A.
B.
C.
D.
The anode will definitely gain weight in a voltaic cell.
Oxidation occurs at the cathode of both cells.
The free energy change, G, is negative for the voltaic cell.
The electrons in the external wire flow from cathode to anode in
an electrolytic cell.
E. None of these statements is correct.
13.Which one of the following pairs of substances could be used to
construct a single redox electrode (i.e., they have an element in
common, but in different oxidation states)?
A.
B.
C.
D.
E.
HCl and ClH+ and OHH2O and H+
Fe3+ and Fe2O3
MnO2 and Mn2+
14.Which one of the following statements about electrochemical cells is
correct?
A. In a salt bridge, current is carried by cations moving toward the
anode, and anions toward the cathode.
B. In the external wire, electrons travel from cathode to anode.
C. The anode of a voltaic cell is labeled minus (-).
D. Oxidation occurs at the cathode, in an electrolytic cell.
E. None of these statements is correct.
15.Which of the following solids is commonly used as an inactive
electrode in electrochemical cells?
A.
B.
C.
D.
E.
zinc
graphite
copper
iron
sodium
5
16.Which component of the following cell notation is the anode?
P | Q || R | S
A.
B.
C.
D.
E.
P
Q
R
S
One of the | symbols is the anode.
17.A voltaic cell is prepared using copper and silver. Its cell notation is
shown below.
Cu(s) | Cu2+(aq) || Ag+(aq) | Ag(s)
Which of the following processes occurs at the cathode?
A.
B.
C.
D.
E.
Cu(s)  Cu2+(aq) + 2eCu2+(aq) + 2e-  Cu(s)
Ag(s)  Ag+(aq) + eAg+(aq) + e-  Ag(s)
Cu(s) + 2Ag+(aq)  Cu2+(aq) + 2Ag(s)
18.A voltaic cell prepared using aluminum and nickel has the following
cell notation.
Al(s) | Al3+(aq) || Ni2+(aq) | Ni(s)
Which of the following reactions occurs at the anode?
A.
B.
C.
D.
E.
Al(s)  Al3+(aq) + 3eAl3+(aq) + 3e  Al(s)
Ni(s)  Ni2+(aq) + 2eNi2+(aq) + 2e-  Ni(s)
None of these choices is correct.
6
19.A voltaic cell prepared using aluminum and nickel has the following
cell notation.
Al(s) | Al3+(aq) || Ni2+(aq) | Ni(s)
Which of the following represents the correctly balanced
spontaneous reaction equation for the cell?
A.
B.
C.
D.
E.
Ni2+(aq) + Al(s)  Al3+(aq) + Ni(s)
3Ni2+(aq) + 2Al(s)  2Al3+(aq) + 3Ni(s)
Ni(s) + Al3+(aq)  Ni2+(aq) + Al(s)
3Ni(s) + 2Al3+(aq)  3Ni2+(aq) + 2Al(s)
None of these choices is correct.
20.A voltaic cell prepared using zinc and iodine has the following cell
notation.
Zn(s) | Zn2+(aq) || I-(aq) | I2(s) | C (graphite)
Which of the following equations correctly represents the balanced,
spontaneous, cell reaction?
A.
B.
C.
D.
E.
2I-(aq) + Zn2+(aq)  I2(s) + Zn(s)
I2(s) + Zn(s)  2I-(aq) + Zn2+(aq)
2I-(aq) + Zn(s)  I2(s) + Zn2+(aq)
I2(s) + Zn2+(aq)  2I-(aq) + Zn(s)
None of these, since graphite must be in the equation.
7
21.A cell can be prepared from copper and tin. What is the Ecell for the
cell that forms from the following half-reactions?
Cu2+(aq) + 2eSn4+(aq) + 2eA.
B.
C.
D.
E.
Cu(s); E = 0.34 V
Sn2+(aq); E = 0.13 V
0.47 V
0.21 V
-0.21 V
-0.47 V
0.42 V
22.What is the Ecell for the cell represented by the combination of the
following half-reactions?
2Hg2+(aq) + 2eCr3+ (aq) + 3eA.
B.
C.
D.
E.
Hg22+(aq); E= 0.92 V
Cr(s); E= -0.74 V
-0.18 V
0.18 V
1.28 V
1.66 V
2.12 V
23.What is the Ecell for the cell represented by the combination of the
following half-reactions?
ClO4-(aq) + 8H+(aq) + 8eVO2+(aq) + 2H+(aq) + eA.
B.
C.
D.
E.
Cl-(aq) + 4H2O(l); E = 1.389 V
VO+(aq) + H2O(l); E = 0.991 V
-0.398 V
-2.380 V
0.398 V
2.380 V
None of these choices is correct.
8
24.The redox reaction of peroxydisulfate with iodide has been used for
many years as part of the iodine clock reaction which introduces
students to kinetics. If Ecell= 1.587 V and E of the cathode half-cell is
0.536 V, what is E of the anode half-cell?
S2O82-(aq) + 2H+ + 2I-(aq)  2HSO4-(aq) + I2(aq)
A.
B.
C.
D.
E.
-1.051 V
-2.123 V
1.051 V
2.123 V
None of these choices is correct.
25.The voltaic cell made up of cobalt, copper and their M2+ ions, has Ecell
= 0.62 V. If E of the cathode half-cell is 0.34 V, what is E of the
anode half-cell?
Cu2+(aq) + Co(s)  Cu(s) + Co2+(aq)
A.
B.
C.
D.
E.
-0.28 V
-0.96V
0.28 V
0.96 V
None of these choices is correct.
26.Given that E for X + e-  Y is greater than E for A + 2e-  B, it is
correct to say that, under standard conditions
A.
B.
C.
D.
E.
X will oxidize A.
Y will oxidize A.
Y will reduce A.
B will oxidize X.
B will reduce X.
9
27.Examine the following half-reactions and select the strongest
oxidizing agent among the substances.
[PtCl4]2-(aq) + 2ePt(s) + 4Cl-(aq); E = 0.755 V
RuO4(s) + 8H+(aq) + 8eRu(s) + 4H2O(l); E = 1.038 V
2+
FeO4 (aq) + 8H (aq) + 3e
Fe3+(aq) + 4H2O(l); E = 2.07 V
H4XeO6(aq) + 2H+(aq) + 2eXeO3(aq) + 3H2O(l); E = 2.42 V
A.
B.
C.
D.
E.
[PtCl4]2-(aq)
RuO4(s)
HFeO4-(aq)
H4XeO6(aq)
Cl-(aq)
28.Examine the following half-reactions and select the strongest
oxidizing agent among the species listed.
Cr2+(aq) + 2eFe2+(aq) + 2eSr2+(aq) + 2eCo2+(aq) + 2eA.
B.
C.
D.
E.
Cr(s); E = -0.913 V
Fe(s); E = -0.447 V
Sr(s); E = -2.89 V
Co(s); E = -0.28 V
Cr2+(aq)
Fe(s)
Fe2+(aq)
Sr2+(aq)
Co2+(aq)
10
29.Examine the following half-reactions and select the weakest
oxidizing agent among the species listed.
AuBr4-(aq) + 3eAu(s) + 4Br-(aq); E = 0.854 V
Mn2+(aq) + 2eMn(s); E = -1.185 V
+
K (aq) + e
K(s); E = -2.931 V
+
F2O(aq) + 2H (aq) + 4e2F-(aq) + H2O(l); E = 2.153 V
A.
B.
C.
D.
E.
AuBr4-(aq)
Mn2+(aq)
K+(aq)
F2O(aq)
H+(aq)
30.Examine the following half-reactions and select the strongest
reducing agent among the species listed.
PbI2(s) + 2eCa2+(aq) + 2ePt2+(aq) + 2eBr2(l) + 2eA.
B.
C.
D.
E.
Pb(s) + 2I-(aq); E = -0.365 V
Ca(s); E = -2.868 V
Pt(s); E = 1.18 V
2Br-(aq); E = 1.066 V
Pb(s)
Ca(s)
Pt(s)
Br-(aq)
Pt2+(aq)
11
31.Examine the following half-reactions and select the strongest
reducing agent among the species listed.
HgO(s) + H2O(l) + 2eHg(l) + 2OH-(aq); E = 0.0977 V
Zn(OH)2(s) + 2eZn(s) + 2OH-(aq); E = -1.25 V
Ag2O(s) + H2O(l) + 2eAg(s) + 2OH-(aq); E = 0.342 V
B(OH)3(aq) + 7H+(aq) + 8eBH4-(aq) + 3H2O(l); E = -0.481 V
A.
B.
C.
D.
E.
Hg(l)
Zn(s)
Ag(s)
BH4-(aq)
Zn(OH)2(s)
32.Examine the following half-reactions and select the weakest reducing
agent among the substances.
Cr(OH)3(s) + 3eCr(s) + 3OH-(aq); E= -1.48 V
SnO2(s) + 2H2O(l) + 4eSn(s) + 4OH-(aq); E = -0.945 V
MnO2(s) + 4H+(aq) + 2eMn2+(aq) + 2H2O(l); E = 1.224 V
Hg2SO4(s) + 2e2Hg(l) + SO42-(aq); E = 0.613 V
A.
B.
C.
D.
E.
Cr(s)
Sn(s)
Mn2+(aq)
Hg(l)
OH-(aq)
12
33.Calculate Ecell and indicate whether the overall reaction shown is
spontaneous or nonspontaneous.
I2(s) + 2eCr3+(aq) + 3e-
2I-(aq); E = 0.53 V
Cr(s); E = -0.74 V
Overall reaction:
2Cr(s) + 3I2(s)  2Cr3+(aq) + (aq) + 6I-(aq)
A.
B.
C.
D.
E.
Ecell = -1.27 V, spontaneous
Ecell = -1.27 V, nonspontaneous
Ecell = 1.27 V, spontaneous
Ecell = 1.27 V, nonspontaneous
Ecell = 1.54 V, spontaneous
34.Calculate Ecell and indicate whether the overall reaction shown is
spontaneous or nonspontaneous.
Co3+(aq) + eCo2+(aq); E = 1.82 V
MnO4-(aq) + 2H2O(l) + 3eMnO2(s) + 4OH-(aq); E = 0.59 V
Overall reaction:
MnO4-(aq) + 2H2O(l) + 3Co2+(aq)  MnO2(s) + 3Co3+(aq) + 4OH-(aq)
A.
B.
C.
D.
E.
Ecell = -1.23 V, spontaneous
Ecell = -1.23 V, nonspontaneous
Ecell = 1.23 V, spontaneous
Ecell = 1.23 V, nonspontaneous
Ecell = -0.05 V, nonspontaneous
13
35.Calculate Ecell and indicate whether the overall reaction shown is
spontaneous or nonspontaneous.
O2(g) + 4H+(aq) + 4e2H2O(l); E = 1.229 V
3+
Al (aq) + 3e
Al(s); E = -1.662 V
Overall reaction:
4Al(s) + 3O2(g) + 12H+(aq)  4Al3+(aq) + 6H2O(l)
A.
B.
C.
D.
E.
Ecell = -2.891 V, nonspontaneous
Ecell = -2.891 V, spontaneous
Ecell = 2.891 V, nonspontaneous
Ecell = 2.891 V, spontaneous
Spontaneous, but none of these values of Ecell is correct.
36.Calculate Ecell and indicate whether the overall reaction shown is
spontaneous or nonspontaneous.
H2O2(aq) + 2H+(aq) + 2e2H2O(l); E = 1.77 V
3+
2+
Fe (aq) + e
Fe (aq); E = 0.77 V
Overall reaction:
2Fe3+(aq) + 2H2O(l)  H2O2(aq) + 2H+(aq) + 2Fe2+(aq)
A.
B.
C.
D.
E.
Ecell = -1.00 V, nonspontaneous
Ecell = -1.00 V, spontaneous
Ecell = 1.00 V, nonspontaneous
Ecell = 1.00 V, spontaneous
Ecell = -0.23 V, nonspontaneous
14
37.When metal A is placed in a solution of metal ions B2+, a reaction
occurs between A and B2+, and metal ions A2+ appear in the solution.
When metal B is placed in acid solution, gas bubbles form on its
surface. When metal A is placed in a solution of metal ions C2+, no
reaction occurs. Which of the following reactions would not occur
spontaneously?
A.
B.
C.
D.
E.
C(s) + 2H+(aq)  H2(g) + C2+(aq)
C(s) + A2+(aq)  A(s) + C2+(aq)
B(s) + C2+(aq)  C(s) + B2+(aq)
A(s) + 2H+(aq)  H2(g) + A2+(aq)
B(s) + 2H+(aq)  H2(g) + B2+(aq)
38.Which of the following conditions is most likely to apply to a fullycharged secondary cell?
A.
B.
C.
D.
E.
Ecell = Ecell
Ecell = 0
Q=1
Q<K
Q=K
39.A battery is considered "dead" when
A.
B.
C.
D.
E.
Q<1
Q=1
Q>1
Q=K
Q/K = 0
15
40.What is the value of the equilibrium constant for the cell reaction
below at 25C? Ecell = 0.30 V
Sn2+(aq) + Fe(s)
A.
B.
C.
D.
E.
Sn(s) + Fe2+(aq)
1.2  105
1.4  1010
8.6  10-6
7.1  10-11
2.3  1023
Balance the following redox reaction in acidic solution.
1.
Balance the following redox reaction in acidic solution.
Fe2+(aq)
2.
+
MnO4-(aq) 
Fe3+(aq) + Mn2+(aq)
Balance the following redox reaction in acidic solution.
Cr2O72-(aq) + I-(aq)  Cr3+(aq) + I2(s)
3.
Balance the following redox reaction in basic solution.
MnO4-(aq) + C2O42-(aq)  MnO2(s) + CO32-(aq)
4.
Balance the following redox reaction in basic solution.
MnO4-(aq) + I-(aq)  MnO4-2(s) + IO3-(aq)
5.
Balance the following redox reaction in basic solution.
MnO4-(aq) + CN-(aq)  MnO2(s) + OCN-(aq)
Cell notation (line notation): A cell diagram shows the components of an
electrochemical cell in a symbolic way. (Anode to cathode)
16
Zn(s)|Zn++(aq) || Cu++(aq)|Cu(s)
Standard hydrogen electrode: (S.H. E.) :
Pt(s) | H2(g, 1 atm) |2H+(aq, 1M)
SHE with copper electrode notation:
Pt(s) | H2(g, 1 atm) |2H+(aq, 1M) || Cu2+(1M) | Cu(s)
Use pt electrode for the ion with two different charges:
Pt(s) | Sn2+(aq), Sn4+(aq) || Ag+(aq) | Ag(s)
7.
Write cell notation for the following two half cell reactions.
Cu(s)  Cu2+(aq) + 2eAg(s)  Ag+(aq) + e-
8.
Write cell notation for the zinc electrode with hydrogen
electrode.
9.
Write overall reaction for the following cell notation
Sc(s)| Sc3+(aq) ||Zn2+(aq)|Zn(s)
10.
Write a cell notation in which Al(s) is oxidized to Al3+ and Zn2+ is
reduced to Zn(s)
11.
Draw a voltaic cell in which silver ion is displaced from solution
by aluminum metal. Label the cathode and anode. Show the
direction of the flow of electrons. Also indicate the direction of flow
of cations and anions from a KNO3 (aq) salt bridge. Write two half cell
reactions and overall reaction. Identify oxidizing and reducing agent.
Overall reaction and two half cells E°red. Values are given
17
12.
Determine E°cell for the following reaction:
Fe(s) + Cu2+(aq)  Fe2+(aq) + Cu(s)
Fe2+ + 2e-  Fe(s)
Cu2+(aq) + 2e  Cu(s)
13.
E° = -0.44V
E° = 0.34V
Calculate E°cell
Zn(s) + Cu++(aq)  Zn++(aq) + Cu(s)
Zn(s)  Zn++(aq) + 2eCu++(aq) + 2e-  Cu(s)
Zn2+/Zn(s) = -0.76V; Cu2+/Cu(s) = 0.34V
Two half cells oxidation reactions are given
Cu(s)  Cu2+(aq) + 2eAg(s)  Ag+(aq) + eAl(s)  Al3+(aq) + 3eZn(s)  Zn+2(aq) + 2eTwo half cells reduction/oxidation reactions are given
2Fe3+(aq) + 2e- 2Fe2+(aq)
Zn(s)  Zn2+(aq) + 2eCu2+(aq) + 2e-  Cu(s)
H2(g)  2H+(aq) + 2eTwo half cells reduction reactions are given
Zn+2(aq) + 2e-  Zn(s)
Cl2(g) + 2e-  2Cl-(aq)
E° = -0.763
E° = 1.360
18
Practice problems
14.
PbO2(s) + Pb(s) + 2H2SO4  2PbSO4(s) + 2H2O(l)
15.
Ag(s)  Ag1+(aq) + eCu(s)  Cu2+ + 2e-
16.
Fe2+(aq)  Fe3+(aq) + e- E°ox = -0.77V
Co2+(aq)  Co3+ + eE°ox = -1.82V
17.
Br2(l) + 2e-  2Br-(aq) E°red = +1.07V
I2(s) + 2e 2I1-(aq)
E°red = +0.54V
18.
Rh3+(aq) + 3e-  Rh(s) Reduction
Cd(s)  Cd2+(aq) + 2e- Oxidation
E°ox = -0.80V
E°ox = -0.34V
E°Rh3+/Rh = 0.80V and E°Cd2+/Cd = -0.40V
19.
Ni2+(aq) + 2e-  Ni(s)
Cr3+(aq) + 3e-  Cr(s)
E°Ni2+ = -0.25V
E°Cr3+ = -0.74V
20.
Ni2+(aq) + 2e- Ni(s)
Cr3+(aq) + 3e- Cr(s)
E°Ni2+ = -0.25V
E°Cr3+ = -0.74V
21.
Write line notation for the following redox reaction.
5Fe(s) + 2MnO4-(aq) + 16H+(aq)  5Fe2+(aq) + 2Mn2+(aq) + 8H2O(l)
22.
Calculate E°cell for the following reaction
Al(s) + NO3-(aq) + 4H+(aq)  Al3+(aq) + NO(g) + 2H2O(l)
23.
Calculate ∆G° for the following reaction.
I2(s) + 2Br-(aq)  2I-(aq) + Br2(l)
Br2 /Br-= 1.09V and I2/I- = 0.54V
19
24.
Calculate Ecell for the following reaction (ans: 1.41V)
3Cu(s) + 2MnO4-(aq) + 8H+(aq)  3Cu2+(aq) + 2MnO2(s) + 4H2O(l)
[MnO4-]0 = 2.0M, [H+]0 = 1.0M, [Cu2+]0 = 0.010M
25.
Calculate equilibrium K for the following redox reaction.
Cu(s) + 2H+(aq)  Cu2+(aq) + H2(g)
∆G = -nFE where F is a Faraday constant = 96,485 or 96,500 C/mol.e-
26. Draw a diagram, show balanced equations, and write the notation
for a voltaic cell that consists of one half cell with a “Cr” bar in
Cr(NO3)3 solution, another half-cell with an “Ag” bar in an AgNO3
solution, and a KNO3 salt bridge.
27. Calculate the standard free energy change at 25°C for the following
reaction. The standard cell potential is 1.10V at 25°C.
Zn(s) + Cu2+(aq)  Zn2+(aq) + Cu(s)
Answer: -212kJ
28. Balance the following redox reaction in acidic solution.
Fe2+(aq)
+
MnO4-(aq) 
Fe3+(aq) + Mn2+(aq)
29. Write the cell reaction for the following voltaic cell.
Tl(s)| Tl+(aq) || Sn2+(aq) | Sn(s)
30.
Write the cell reaction for the following voltaic cell.
Zn(s)| Zn++(aq) || Fe3+(aq), Fe2+(aq)
31.
Write the cell reaction for the following voltaic cell.
Zn(s)| Zn++(1.0M) || H+(1.0M)|H2(1.0atm)|Pt(s)
20
32.
Calculate E°cell for the following cell.
Zn2+(aq) + 2Fe2+(aq)  Zn(s) + 2Fe3+(aq) Zn2+/Zn = -0.76V
Fe3+/Fe2+= 0.77V
33.
Draw a diagram, show balanced equations, and write the
notation for a voltaic cell that consists of one half cell with a “Cr”
bar in Cr(NO3)3 solution, another half-cell with an “Ag” bar in an
AgNO3 solution, and a KNO3 salt bridge.
34.
Calculate the standard free energy change at 25°C for the
following reaction. The standard cell potential is 1.10V at
25°C.
Zn(s) + Cu2+(aq)  Zn2+(aq) + Cu(s)
Answer: -212kJ
35.
Balance the following redox reaction in acidic solution.
Fe2+(aq)
+
MnO4-(aq)

Fe3+(aq)
+
Mn2+(aq)
36.
Write the cell reaction for the following voltaic cell.
Tl(s)| Tl+(aq) || Sn2+(aq) | Sn(s)
37.
Write the cell reaction for the following voltaic cell.
Zn(s)| Zn++(aq) || Fe3+(aq), Fe2+(aq)
38.
Write the cell reaction for the following voltaic cell.
Zn(s)| Zn++(1.0M) || H+(1.0M)|H2(1.0atm)|Pt(s)
39.
Calculate E°cell for the following cell.
Zn2+(aq) + 2Fe2+(aq)  Zn(s) + 2Fe3+(aq)
40. Write cell notation for Zn(s) + 2Fe3+(aq)  Zn2+(aq) + 2Fe2+(aq)
41. Determine E°cell for the following reaction:
Fe(s) + Cu2+(aq)  Fe2+(aq) + Cu(s)
Fe2+ + 2e-  Fe(s)
E° = -0.44V
2+
Cu (aq) + 2e  Cu(s)
E° = 0.34V
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42. Use the data below to answer the following questions:
Sn4+(aq) + 2e-  Sn2+(aq)
E° = +0.13V
2+
Sn (aq) + 2e-  Sn(s)
E° = -0.14V
a.
b.
c.
Which is the stronger reducing agent?
Calculate E°cell for the above two half cell reactions.
Calculate free energy ∆G° for the above cell.
(F = 96,487 C/e-)
43. The charge on one electron is 1.60219 x 10-19C. What is the charge of
one mole of electrons?
44. Write overall reaction for the following two half cell reactions:
Zn2+(aq) + 2e-  Zn(s)
Fe3+(aq) + e-  Fe2+
45. Calculate E°cell for the following reaction;
2Na(s) + 2H2O(l)  2NaOH(aq) + H2(g)
E°H2O/H2 = -0.83V; E°Na+/Na= - 2.71V
46. When copper foil is placed in a silver nitrate solution, the solution
turns light blue and silver precipitates. What is the equilibrium
constant for the following reaction:
Cu(s) + 2AgNO3(aq)  Cu(NO3)2(aq) + 2Ag(s)
Cu(s)  Cu2+(aq)
E° = -0.34V
+
Ag (aq)  Ag(s)
E° = +0.80V
47. How many faradays of electricity are given off in this spontaneous
reaction when 190.5g of copper metal are used up for the above
reaction?
48. What is the cell voltage for the following cell at room temperature?
Zn(s) | Zn2+(aq, 0.010M) || H+(aq, 2.5M)|H2(g, 0.30 atm)
Zn2+/Zn(s) = 0.76V
49. Calculate Ecell for the following concentration cell:
22
Cu(s)  Cu2+(aq, 0.10M) + 2eCu2+(aq, 1.0M)  Cu(s)
50.Consider a Galvanic cell that uses the
reaction:Zn(s)+2H+(aq) Zn2+(aq) + H2(g)
Calculate Ecell at 25°C when [H+] = 1.0M, [Zn2+] = 0.0010M, and
PH2 = 0.10atm.
E°Zn2+Zn(s) = -0.76V
(answer: 0.88V)
51.Consider a Galvanic cell that uses the reaction:
Cu(s)+ 2Fe3+(aq) Cu2+(aq) + 2Fe2+(aq)
What is the potential at 25°C when [Fe3+] = 1.0 x 10-4M, [Cu2+] =
0.25M, and [Fe2+]= 0.20M (answer: 0.25V)
52.The following cell has a potential of 0.55V at 25°C:
Pt(s)|H2(1 atm)|H+(?M) || Cl-(1M)|Hg2Cl2(s)|Hg(l)
What is the pH of the solution in the anode compartment?
(answer:4.6)
53.Balance the following redox reaction in an acidic solution.
Br-(aq) + Cr2O72-(aq)  Br2(g) + Cr3+(aq)
54.How many amperes must be passed through a Downs cell to
produce sodium metal at a rate of 30.0kg/h? (answer:
34,700)
55.
For the reaction: Zn2+(aq) + Cu(s) <-> Zn(s) + Cu2+(aq)
Zn2+(aq) + 2e-  Zn(s)
Cu  Cu2+(aq) + 2e-
E° = -0.76V
E° = -0.34V
a. Calculate E°cell.
b. Calculate the ∆G°.
56.
For the reaction:
VO2+(aq) + 2H+(aq) + e-  VO2+(aq) + H2O(l) E°= +1.00V
Zn2+(aq) + 2e- <-> Zn(s)
E°= -0.76V
23
a. Calculate E°cell.
57.
b.
Calculate the ∆G°.
Calculate Ecell for a galvanic cell based on the following half
reactions at 25°C.
Cd2+(aq) + 2e-  Cd(s)
E° = -0.40V
2+
Pb (aq) + 2e  Pb(s)
E°= -0.13V
Where [Cd2+] = 0.010M and [Pb2+] = 0.100M.
58. Calculate Ecell for a galvanic cell based on the following half eactions
at 25°C.
FeO42-(aq) + 8H+ +3e-  Fe3+(aq) + 4H2O
E° = -0.40V
+
O2 + 4H (aq) + 4e  2H2O
E°= -0.13V
Where [FeO42-] = 0.0020M and [Fe3+] = 0.0010M.
[O2] = 0.000010 atm
pH = 5.2
59. For a galvanic cell the half reactions are:
Cu2+(a) + 2e-  Cu(s)
E° = 0.34V
2+
3+
Cr2O7 (aq) + 14H + 6e-  2Cr (aq) + 7H2O
E° = 1.33V
Calculate equilibrium constant K for the above cell.
60. Consider the reaction: Ni2+(aq) + Sn(s)  Ni(s) + Sn2+(aq)
Ni2+/Ni  -0.23V,
Sn2+/Sn(s)  -0.14V
a. Calculate E°cell. b.
Calculate equilibrium K at 25°C.
61. How many grams of copper can be reduced by applying a 3.00 A
current for 16.2 min to a solution containing Cu2+ ions?
62. What volume of H2 gas and O2 gas is produced by electrolyzing water
at a current of 4.00 A for 12.0 minutes (assuming under ideal
conditions)?
63. The following cell has a potential of 0.55V at 25°C:
Pt | H2(1 atm) | H+ (?M) || Cl-(1M | Hg2Cl2(s) | Hg(l)
Write overall reaction and calculate Ecell for hydrogen electrode?
24
64. The following cell has a potential of 0.55V at 25°C:
Pt | H2(1 atm) | H+ (?M) || Cl-(1M | Hg2Cl2(s) | Hg(l)
What is the pH of the solution in the anode compartment?
25