74 MHR ● Chemistry 12 Solutions Manual 978-0-07-106042-4
10. Write a balanced ionic equation that represents the reaction in a galvanic cell involving silver
and nickel.
What Is Required?
You are asked to write a balanced ionic equation to represent a galvanic reaction.
What Is Given?
You are given the galvanic cell involving silver and nickel.
Plan Your Strategy
Act on Your Strategy
Write the oxidation half-reaction.
Ni(s) → Ni
2+
(aq) + 2e
–
Write the reduction half-reaction.
Ag
+
(aq) + e
–
→ Ag(s)
Balance the electrons lost and gained in the
two half
-reactions.
The number of electrons lost is 2 and the
number gained is 1. Therefore, the gain needs
to be multiplied by 2.
2Ag
+
(aq) + 2e
–
→ 2Ag(s)
Combine the two half-reactions, cancelling
the electrons lost and gained.
Ni(s) + 2Ag
+
(aq) → 2Ag(s) + Ni
2+
(aq)
Check Your Solution
The two sides are balanced by mass and charge. Therefore, the reaction is balanced.
Unit 5 Part B ● MHR 75
Calculating a Standard Cell Potential, Given a Net Ionic Equation
Calculating a Standard Cell Potential, Given a Chemical Reaction
(Student textbook page 647)
11. For the reaction Cl
2
(g) + 2Br
–
(aq) → 2Cl
–
(aq) + Br
2
(ℓ):
a. write the oxidation and reduction half-reactions.
b. determine the standard cell potentials for galvanic cells in which these reactions occur.
c. predict whether the reaction will proceed spontaneously as written.
What Is Required?
a. You need to write the oxidation and reduction half reactions for a given redox reaction.
b. You need to determine the standard cell potential for the galvanic cell given.
c. You need to determine whether the reaction will proceed spontaneously as written.
What Is Given?
You are given the balanced net ionic equation.
You have a table of standard reduction potentials.
Plan Your Strategy
Act on Your Strategy
a. Break the redox reaction into the two
half
-reactions that make up the overall
reaction.
Oxidation: 2Br
–
(aq) → 2Br
–
(aq) + 2e
–
Reduction: Cl
2
(g) + 2e
–
→ 2Cl
–
(aq)
b. Calculate the standard cell-potential for
the galvanic cell by locating the relevant
reduction potentials in a table of standard
reduction potentials.
Br
2
(ℓ) + 2e
–
→ 2Br
–
(aq)
o
anode
1.07 VE = +
Cl
2
(g) + 2e
–
→ 2Cl
–
(aq)
o
cathode
1.36 VE = +
Subtract the reduction potentials to
determine the cell potential by using the
formula
o o o
cell cathode anode
E E E= -
.
o o o
cell cathode anode
1.36 V (1.07 V)
0.29 V
E E E= -
= -
= +
c. Predict whether the reaction will proceed
spontaneously.
Since the cell potential is positive, the reaction
is spontaneous in the direction written.
Check Your Solution
The half-reactions are correct, and the reduction potentials are correct according to the table
of standard reduction potentials on page 748 of the Chemistry 12 student textbook. The
prediction that a positive cell potential will result in a spontaneous reaction is correct as well.
76 MHR ● Chemistry 12 Solutions Manual 978-0-07-106042-4
12. For the reaction Mg(s) + 2AgNO
3
(aq) → Mg(NO
3
)
2
(aq) + 2Ag(s):
a. write the oxidation and reduction half-reactions.
b. determine the standard cell potentials for galvanic cells in which these reactions occur.
c. predict whether the reaction will proceed spontaneously as written.
What Is Required?
a. You need to write the oxidation and reduction half reactions for a given redox reaction.
b. You need to determine the standard cell potential for the galvanic cell given.
c. You need to determine whether the reaction will proceed spontaneously as written.
What Is Given?
You are given the balanced net ionic equation.
You have a table of standard reduction potentials.
Plan Your Strategy
Act on Your Strategy
a. Break the redox reaction into the two
half
-reactions that make up the overall
reaction.
Oxidation: Mg(s) → Mg
2+
(aq) + 2e
–
Reduction: Ag
+
(aq) + 1e
–
→ Ag(s)
b. Calculate the standard cell-potential for
the galvanic cell by locating the relevant
reduction potentials in a table of standard
reduction potentials.
Mg
2+
(aq) + 2e
–
→ Mg(s)
o
anode
2.37 VE = -
Ag
+
(aq) + 1e
–
→ Ag(s)
o
cathode
0.80 VE = +
Subtract the reduction potentials to
determine the cell potential by using the
formula
o o o
cell cathode anode
E E E= -
.
o o o
cell cathode anode
0.80 V ( 2.37 V)
3.17 V
E E E= -
= - -
= +
c. Predict whether the reaction will proceed
spontaneously.
Since the cell potential is positive, the reaction
is spontaneous in the direction written.
Check Your Solution
The half-reactions are correct, and the reduction potentials are correct according to the table
of standard reduction potentials on page 748 of the Chemistry 12 student textbook. The
prediction that a positive cell potential will result in a spontaneous reaction is correct as well.
Unit 5 Part B ● MHR 77
13. For the reaction Sn(s) + 2HBr(aq) → SnBr
2
(aq) + H
2
(g):
a. write the oxidation and reduction half-reactions.
b. determine the standard cell potentials for galvanic cells in which these reactions occur.
c. predict whether the reaction will proceed spontaneously as written.
What Is Required?
a. You need to write the oxidation and reduction half reactions for a given redox reaction.
b. You need to determine the standard cell potential for the galvanic cell given.
c. You need to determine whether the reaction will proceed spontaneously as written.
What Is Given?
You are given the balanced net ionic equation.
You have a table of standard reduction potentials.
Plan Your Strategy
Act on Your Strategy
a. Break the redox reaction into the two
half
-reactions that make up the overall
reaction.
Oxidation: Sn(s) → Sn
2+
(aq) + 2e
–
Reduction: 2H
+
+ 2e
–
→ H
2
(g)
b. Calculate the standard cell-potential for
the galvanic cell by locating the relevant
reduction potentials in a table of standard
reduction potentials.
Sn
2+
(aq) + 2e
–
→ Sn(s)
o
anode
0.14 VE = -
2H
+
(aq) + 2e
–
→ H
2
(g)
o
cathode
0.00 VE =
Subtract the reduction potentials to
determine the cell potential by using the
formula
o o o
cell cathode anode
E E E= -
.
o o o
cell cathode anode
0.00 V ( 0.14 V)
0.14 V
E E E= -
= - -
= +
c. Predict whether the reaction will proceed
spontaneously.
Since the cell potential is positive, the reaction
is spontaneous in the direction written.
Check Your Solution
The half-reactions are correct, and the reduction potentials are correct according to the table
of standard reduction potentials on page 748 of the Chemistry 12 student textbook. The
prediction that a positive cell potential will result in a spontaneous reaction is correct as well.
78 MHR ● Chemistry 12 Solutions Manual 978-0-07-106042-4
14. For the reaction Cr(s) + 3AgCl(s) → CrCl
3
(aq) + 3Ag(s):
a. write the oxidation and reduction half-reactions.
b. determine the standard cell potentials for galvanic cells in which these reactions occur.
c. predict whether the reaction will proceed spontaneously as written.
What Is Required?
a. You need to write the oxidation and reduction half reactions for a given redox reaction.
b. You need to determine the standard cell potential for the galvanic cell given.
c. You need to determine whether the reaction will proceed spontaneously as written.
What Is Given?
You are given the balanced net ionic equation.
You have a table of standard reduction potentials.
Plan Your Strategy
Act on Your Strategy
a. Break the redox reaction into the two
half
-reactions that make up the overall
reaction.
Oxidation: Cr(s) → Cr
3+
(aq) + 3e
–
Reduction: Ag
+
(aq) + 1e
–
→ Ag(s)
b. Calculate the standard cell-potential for
the galvanic cell by locating the relevant
reduction potentials in a table of standard
reduction potentials.
Cr
3+
(aq) + 3e
–
→ Cr(s)
o
anode
0.74 VE = -
Ag
+
(aq) + 1e
–
→ Ag(s)
o
cathode
0.80 VE = +
Subtract the reduction potentials to
determine the cell potential by using the
formula
o o o
cell cathode anode
E E E= -
.
o o o
cell cathode anode
0.80 V ( 0.74 V)
1.54 V
E E E= -
= - -
= +
c. Predict whether the reaction will proceed
spontaneously.
Since the cell potential is positive, the reaction
is spontaneous in the direction written.
Check Your Solution
The half-reactions are correct, and the reduction potentials are correct according to the table
of standard reduction potentials on page 748 of the Chemistry 12 student textbook. The
prediction that a positive cell potential will result in a spontaneous reaction is correct as well.
Unit 5 Part B ● MHR 79
15. For the reaction 3Fe(s) + 2Cr(NO
3
)
3
(aq) → 2Cr(s) + 3Fe(NO
3
)
2
(aq):
a. write the oxidation and reduction half-reactions.
b. determine the standard cell potentials for galvanic cells in which these reactions occur.
c. predict whether the reaction will proceed spontaneously as written.
What Is Required?
a. You need to write the oxidation and reduction half reactions for a given redox reaction.
b. You need to determine the standard cell potential for the galvanic cell given.
c. You need to determine whether the reaction will proceed spontaneously as written.
What Is Given?
You are given the balanced net ionic equation.
You have a table of standard reduction potentials.
Plan Your Strategy
Act on Your Strategy
a. Break the redox reaction into the two
half
-reactions that make up the overall
reaction.
Oxidation: Fe(s) → Fe
2+
(aq) + 2e
–
Reduction:
Cr
3+
(aq) + 3e
–
→ Cr(s)
b. Calculate the standard cell-potential for
the galvanic cell by locating the relevant
reduction potentials in a table of standard
reduction potentials.
Fe
2+
(aq) + 2e
–
→ Fe(s)
o
anode
0.45 VE = -
Cr
3+
(aq) + 3e
–
→ Cr(s)
o
cathode
0.74 VE = -
Subtract the reduction potentials to
determine the cell potential by using the
form
ula
o o o
cell cathode anode
E E E= -
.
o o o
cell cathode anode
0.74 V ( 0.45 V)
0.29 V
E E E= -
= - - -
= -
c. Predict whether the reaction will proceed
spontaneously.
Since the cell potential is negative, the
reaction is not spontaneous in the direction
written.
Check Your Solution
The half-reactions are correct, and the reduction potentials are correct according to the table
of standard reduction potentials on page 748 of the Chemistry 12 student textbook. The
prediction that a negative cell potential will result in a non-spontaneous reaction is correct as
well.
80 MHR ● Chemistry 12 Solutions Manual 978-0-07-106042-4
16. For the reaction 2Al(s) + 3ZnCl
2
(aq) → 3Zn(s) + 2AlCl
3
(aq):
a. write the oxidation and reduction half-reactions.
b. determine the standard cell potentials for galvanic cells in which these reactions occur.
c. predict whether the reaction will proceed spontaneously as written.
What Is Required?
a. You need to write the oxidation and reduction half reactions for a given redox reaction.
b. You need to determine the standard cell potential for the galvanic cell given.
c. You need to determine whether the reaction will proceed spontaneously as written.
What Is Given?
You are given the balanced net ionic equation.
You have a table of standard reduction potentials.
Plan Your Strategy
Act on Your Strategy
a. Break the redox reaction into the two
half
-reactions that make up the overall
reaction.
Oxidation: Al(s) → Al
3+
(aq) + 3e
–
Reduction:
Zn
2+
(aq) + 2e
–
→ Zn(s)
b. Calculate the standard cell-potential for
the galvanic cell by locating the relevant
reduction potentials in a table of standard
reduction potentials.
Al
3+
(aq) + 3e
–
→ Al(s)
o
anode
1.66 VE = -
Zn
2+
(aq) + 2e
–
→ Zn(s)
o
cathode
0.76 VE = -
Subtract the reduction potentials to
determine the cell potential by using the
formula
o o o
cell cathode anode
E E E= -
.
o o o
cell cathode anode
0.76 V ( 1.66 V)
0.90 V
E E E= -
= - - -
= +
c. Predict whether the reaction will proceed
spontaneously.
Since the cell potential is positive, the reaction
is spontaneous in the direction written.
Check Your Solution
The half-reactions are correct, and the reduction potentials are correct according to the table
of standard reduction potentials on page 748 of the Chemistry 12 student textbook. The
prediction that a positive cell potential will result in a spontaneous reaction is correct as well.
Unit 5 Part B ● MHR 81
17. For the reaction 2AgNO
3
(aq) + Zn(s) → 2Ag(s) + Zn(NO
3
)
2
(aq):
a. write the oxidation and reduction half-reactions.
b. determine the standard cell potentials for galvanic cells in which these reactions occur.
c. predict whether the reaction will proceed spontaneously as written.
What Is Required?
a. You need to write the oxidation and reduction half reactions for a given redox reaction.
b. You need to determine the standard cell potential for the galvanic cell given.
c. You need to determine whether the reaction will proceed spontaneously as written.
What Is Given?
You are given the balanced net ionic equation.
You have a table of standard reduction potentials.
Plan Your Strategy
Act on Your Strategy
a. Break the redox reaction into the two
half
-reactions that make up the overall
reaction.
Oxidation: Zn(s) → Zn
2+
(aq) + 2e
–
Reduction:
Ag
+
(aq) + 1e
–
→ Ag(s)
b. Calculate the standard cell-potential for
the galvanic cell by locating the relevant
reduction potentials in a table of standard
reduction potentials.
Zn
2+
(aq) + 2e
–
→ Zn(s)
o
anode
0.76 VE = -
Ag
+
(aq) + 1e
–
→ Ag(s)
o
cathode
0.80 VE = +
Subtract the reduction potentials to
determine the cell potential by using the
formula
o o o
cell cathode anode
E E E= -
.
o o o
cell cathode anode
0.80 V ( 0.76 V)
1.56 V
E E E= -
= - -
= +
c. Predict whether the reaction will proceed
spontaneously.
Since the cell potential is positive, the reaction
is spontaneous in the direction written.
Check Your Solution
The half-reactions are correct, and the reduction potentials are correct according to the table
of standard reduction potentials on page 748 of the Chemistry 12 student textbook. The
prediction that a positive cell potential will result in a spontaneous reaction is correct as well.
82 MHR ● Chemistry 12 Solutions Manual 978-0-07-106042-4
18. For the reaction 3Cu(NO
3
)
2
(aq) + 2Al(s) → 2Al(NO
3
)
3
(aq) + 3Cu(s):
a. write the oxidation and reduction half-reactions.
b. determine the standard cell potentials for galvanic cells in which these reactions occur.
c. predict whether the reaction will proceed spontaneously as written.
What Is Required?
a. You need to write the oxidation and reduction half reactions for a given redox reaction.
b. You need to determine the standard cell potential for the galvanic cell given.
c. You need to determine whether the reaction will proceed spontaneously as written.
What Is Given?
You are given the balanced net ionic equation.
You have a table of standard reduction potentials.
Plan Your Strategy
Act on Your Strategy
a. Break the redox reaction into the two
half
-reactions that make up the overall
reaction.
Oxidation: Al(s) → Al
3+
(aq) + 3e
–
Reduction:
Cu
2+
(aq) + 2e
–
→ Cu(s)
b. Calculate the standard cell-potential for
the galvanic cell by locating the relevant
reduction potentials in a table of standard
reduction potentials.
Al
3+
(aq) + 3e
–
→ Al(s)
o
anode
1.66 VE = -
Cu
2+
(aq) + 2e
–
→ Cu(s)
o
cathode
0.34 VE = +
Subtract the reduction potentials to
determine the cell potential by using the
formula
o o o
cell cathode anode
E E E= -
.
o o o
cell cathode anode
0.34 V ( 1.66 V)
2.00 V
E E E= -
= - -
= +
c. Predict whether the reaction will proceed
spontaneously.
Since the cell potential is positive, the reaction
is spontaneous in the direction written.
Check Your Solution
The half-reactions are correct, and the reduction potentials are correct according to the table
of standard reduction potentials on page 748 of the Chemistry 12 student textbook. The
prediction that a positive cell potential will result in a spontaneous reaction is correct as well.
Unit 5 Part B ● MHR 83
19. For the reaction CuSO
4
(aq) + 2Ag(s) → Ag
2
SO
4
(aq) + Cu(s):
a. write the oxidation and reduction half-reactions.
b. determine the standard cell potentials for galvanic cells in which these reactions occur.
c. predict whether the reaction will proceed spontaneously as written.
What Is Required?
a. You need to write the oxidation and reduction half reactions for a given redox reaction.
b. You need to determine the standard cell potential for the galvanic cell given.
c. You need to determine whether the reaction will proceed spontaneously as written.
What Is Given?
You are given the balanced net ionic equation.
You have a table of standard reduction potentials.
Plan Your Strategy
Act on Your Strategy
a. Break the redox reaction into the two
half
-reactions that make up the overall
reaction.
Oxidation: Ag(s) → Ag
+(
aq) + 1e
–
Reduction:
Cu
2+
(aq) + 2e
–
→ Cu(s)
b. Calculate the standard cell-potential for
the galvanic cell by locating the relevant
reduction potentials in a table of standard
reduction potentials.
Ag
+
(aq) + 1e
–
→ Ag(s)
o
anode
0.80 VE = +
Cu
2+
(aq) + 2e
–
→ Cu(s)
o
cathode
0.34 VE = +
Subtract the reduction potentials to
determine the cell potential by using the
formula
o o o
cell cathode anode
E E E= -
.
o o o
cell cathode anode
0.34V (0.80 V)
0.46 V
E E E= -
= -
= -
c. Predict whether the reaction will proceed
spontaneously.
Since the cell potential is negative, the
reaction is not spontaneous in the direction
written.
Check Your Solution
The half-reactions are correct, and the reduction potentials are correct according to the table
of standard reduction potentials on page 748 of the Chemistry 12 student textbook. The
prediction that a negative cell potential will result in a non-spontaneous reaction is correct as
well.
