Question 1

Determine E°cell for the reaction: MnO4- + 8 H+ + 5 Fe2+ → Mn2+ + 4 H2O + 5 Fe3+. The half reactions are: Fe3+(aq) + e- → Fe2+(aq)   &emsp; E° = +0.771 V
MnO4-(aq) + 8 H+(aq) + 5 e- → Mn2+(aq) + 4 H2O(l)  &emsp;  E° = 1.507 V

Accepted Answer

A)  -2.34 V 
B)  -2.28 V 
C)  2.28 V 
D)  -0.74 V 
E)  0.74 V

Question 2

Choose the INCORRECT statement.

Accepted Answer

A)  A cell diagram is a symbolic way to show cell components. 
B)  An anode is where oxidation occurs. 
C)  A cathode is where reduction occurs. 
D)  Half cells in a cell diagram are separated by a single vertical line. 
E)  The anode is on the left in a cell diagram.

Question 3

3.53 L of 0.362 M CuCl2(aq) solution are electrolyzed for 55.6 minutes with a current of 14.0-amperes. What is [CuCl2] when the electrolysis ends?

Accepted Answer

A)  0.361 M 
B)  0.328 M 
C)  0.120 M 
D)  0.171 M 
E)  0.293 M

Question 4

What mass of silver can be deposited by the passage of a constant current of 5.00 A through a AgNO3 solution for 2.00 hours?

Accepted Answer

A)  40.3 g 
B)  0.0112 g 
C)  0.671 g 
D)  0.373 g 
E)  10.06 g

Question 5

Consider the cell: Ni ∣ Ni2+ (?M) || Cu2+ (0.136 M) ∣ Cu
Ni2+/Ni E° = -0.257 V
Cu2+/Cu E° = 0.340 V
The measured potential of the cell is 0.621 V. What is [Ni2+] at 25°C?

Accepted Answer

A)  2 × 10-2 M 
B)  1 M 
C)  4 × 10-42 M 
D)  0.05 M 
E)  0.4 M

Question 6

Zn+2(aq) + 2 e- → Zn(s) E° = -0.763 V

Accepted Answer

A)  1 and 4 
B)  2 and 4 
C)  3 and 4 
D)  1 and 3 
E)  2 and 3

Question 7

For the reaction: Mg(s) + 2 AgNO3(aq) → 2 Ag(s) + Mg(NO3)2(aq) Write a voltaic diagram for the reaction.

Accepted Answer

A)  Ag(s) | Ag(aq) || Mg2+(aq) | Mg(s) 
B)  Mg(s) ∣ Mg2+ || Ag+ (aq) ∣ Ag (s) 
C)  Mg(s) ∣ Mg2+ || Ag(s) ∣ Ag+ (aq) 
D)  Ag(aq) ∣ Ag(s) || Mg(s) ∣ Mg2+ (aq) 
E)  Ag(s) ∣ Mg2+ (aq) || Ag+ (aq) ∣ Mg(s)

Question 8

Determine E°cell for the reaction: 2 Al + 3 Zn2+ → 2 Al3+ + 3 Zn. The half reactions are: Al3+(aq) + 3 e- → Al(s)   &emsp; E° = -1.676 V
Zn2+(aq) + 2 e- → Zn(s)  &emsp;  E° = -0.763 V

Accepted Answer

A)  0.913 V 
B)  -2.439 V 
C)  2.439 V 
D)  -1.063 V 
E)  -0.913 V

Question 9

The hydrogen standard electrode is the most convenient standard electrode to use.

Accepted Answer

A) True 
 B)False

Question 10

Two cells containing solutions of AgNO3 and CuSO4, respectively, were connected in series and electrolyzed. The cathode in the AgNO3 cell was found to gain 1.078 grams in weight. How much had the cathode in the other cell gained?

Accepted Answer

A)  0.127 g 
B)  0.6354 g 
C)  3.175 g 
D)  0.318 g 
E)  0.254 g

Question 11

Find Ecell at 25°C for the following voltaic cell: Cu(s) ∣ Cu2+(aq) (0.10 M) || Cu2+(aq) (0.85 M) ∣ Cu(s)
The half-reaction is:
Cu2+(aq) + 2 e- → Cu(s) E° = +0.377 volts

Accepted Answer

A)  +0.0209 V 
B)  +0.0550 V 
C)  +0.0275 V 
D)  -0.0209 V 
E)  +0.310 V

Question 12

Determine E°cell for the reaction: 2 Al3+ + 3 Zn → 2 Al + 3 Zn2+. The half reactions are: Al3+(aq) + 3 e- → Al(s)   &emsp; E° = -1.676 V
Zn2+(aq) + 2 e- → Zn(s)  &emsp;  E° = -0.763 V

Accepted Answer

A)  0.913 V 
B)  -2.439 V 
C)  2.439 V 
D)  -1.063 V 
E)  -0.913 V

Question 13

A primary battery is recharged by passing electricity through the battery.

Accepted Answer

A) True 
 B)False

Question 14

Determine E°cell for the reaction: I2 + Cu → 2 I- + Cu2+. The half reactions are: I2(s) + 2 e- → 2 I-(aq)   &emsp; E° = +0.535 V
Cu2+ + 2 e- → Cu  &emsp;  E° = 0.340 V

Accepted Answer

A)  0.730 V 
B)  -0.875 V 
C)  0.875 V 
D)  0.195 V 
E)  -0.195 V

Question 15

What is the cell diagram for the spontaneous cell involving the Fe3+ ∣ Fe2+ (0.771V) half cell and the Zn2+ ∣ Zn (-0.763 V) half cell?

Accepted Answer

A)  Fe2+(aq) ∣ Fe3+(aq) || Zn2+(aq) ∣ Zn(s) 
B)  Pt(s) ∣ Fe2+(aq), Fe3+(aq) || Zn2+(aq) ∣ Zn(s) 
C)  Zn(s) ∣ Zn2+(aq) || Fe3+(aq) ∣ Fe2+(aq) ∣ Pt(s) 
D)  Zn(s) ∣ Zn2+(aq) || Fe3+(aq) ∣ Fe2+(aq) 
E)  Zn(s) ∣ Zn2+(aq) || Fe3+(aq) ∣ Fe2+(aq) ∣ Zn(s)

Question 16

Choose the INCORRECT statement.

Accepted Answer

A)  When a half reaction is reversed, the sign of the potential is changed. 
B)  Reversing a half reaction makes it a reduction potential. 
C)  Each electrochemical cell consists of a reduction half cell and an oxidation half cell. 
D)  A voltaic cell is also called a battery. 
E)  The potential difference of a cell is the voltage of the cell.

Question 17

For the cell reaction at 25°C Cu2+(aq) + Zn(s) → Cu(s) + Zn2+(aq), E°cell = +1.100 V. What is the equilibrium constant for this reaction?

Accepted Answer

A)  3 × 10-19 
B)  2 × 1037 
C)  2 × 10-37 
D)  3 × 1018 
E)  3 × 10-18

Question 18

In the electrolysis of water, oxygen is evolved at the cathode.

Accepted Answer

A) True 
 B)False

Question 19

What is Keq at 25°C of the spontaneous cell made from Ag+/Ag (0.80 V) and Cl2/Cl- (1.36 V) half cells?

Accepted Answer

A)  1073 
B)  10-10 
C)  109 
D)  1019 
E)  10-19

Question 20

Choose the INCORRECT completion of the following sentence: "In the electrolysis of water...

Accepted Answer

A)  ...a direct current must be used." 
B)  ...oxygen is evolved at the cathode." 
C)  ...electrical energy must be supplied continuously because it is an endothermic reaction." 
D)  ...the volume of hydrogen produced is twice the volume of oxygen produced." 
E)  ....one mole of H2 is produced for each two moles of electrons."

Exam 20: Electrochemistry

Determine E°cell for the reaction: MnO₄^- + 8 H⁺+ 5 Fe²⁺ → Mn²⁺ + 4 H₂O + 5 Fe³⁺. The half reactions are: Fe³⁺(aq) + e- → Fe²⁺(aq) E° = +0.771 V MnO₄^-(aq) + 8 H⁺(aq) + 5 e- → Mn²⁺(aq) + 4 H₂O(l) E° = 1.507 V

Choose the INCORRECT statement.

3.53 L of 0.362 M CuCl₂(aq) solution are electrolyzed for 55.6 minutes with a current of 14.0-amperes. What is [CuCl₂] when the electrolysis ends?

What mass of silver can be deposited by the passage of a constant current of 5.00 A through a AgNO₃ solution for 2.00 hours?

Consider the cell: Ni ∣ Ni²⁺ (?M) || Cu²⁺(0.136 M) ∣ Cu Ni²⁺/Ni E° = -0.257 V Cu²⁺/Cu E° = 0.340 V The measured potential of the cell is 0.621 V. What is [Ni²⁺] at 25°C?

Zn+2(aq) + 2 e- → Zn(s) E° = -0.763 V

For the reaction: Mg(s) + 2 AgNO₃(aq) → 2 Ag(s) + Mg(NO₃) ₂(aq) Write a voltaic diagram for the reaction.

Determine E°cell for the reaction: 2 Al + 3 Zn²⁺ → 2 Al³⁺ + 3 Zn. The half reactions are: Al³⁺(aq) + 3 e- → Al(s) E° = -1.676 V Zn²⁺(aq) + 2 e- → Zn(s) E° = -0.763 V

The hydrogen standard electrode is the most convenient standard electrode to use.

Two cells containing solutions of AgNO₃ and CuSO₄, respectively, were connected in series and electrolyzed. The cathode in the AgNO₃ cell was found to gain 1.078 grams in weight. How much had the cathode in the other cell gained?

Find Ecell at 25°C for the following voltaic cell: Cu(s) ∣ Cu2+(aq) (0.10 M) || Cu2+(aq) (0.85 M) ∣ Cu(s) The half-reaction is: Cu2+(aq) + 2 e- → Cu(s) E° = +0.377 volts

Determine E°cell for the reaction: 2 Al³⁺ + 3 Zn → 2 Al + 3 Zn²⁺. The half reactions are: Al3+(aq) + 3 e- → Al(s) E° = -1.676 V Zn²⁺(aq) + 2 e- → Zn(s) E° = -0.763 V

A primary battery is recharged by passing electricity through the battery.

Determine E°cell for the reaction: I₂ + Cu → 2 I- + Cu²⁺. The half reactions are: I₂(s) + 2 e- → 2 I-(aq) E° = +0.535 V Cu²⁺ + 2 e- → Cu E° = 0.340 V

What is the cell diagram for the spontaneous cell involving the Fe³⁺ ∣ Fe²⁺ (0.771V) half cell and the Zn²⁺ ∣ Zn (-0.763 V) half cell?

Choose the INCORRECT statement.

For the cell reaction at 25°C Cu²⁺(aq) + Zn(s) → Cu(s) + Zn²⁺(aq) , E°cell = +1.100 V. What is the equilibrium constant for this reaction?

In the electrolysis of water, oxygen is evolved at the cathode.

What is Keq at 25°C of the spontaneous cell made from Ag⁺/Ag (0.80 V) and Cl₂/Cl- (1.36 V) half cells?

Choose the INCORRECT completion of the following sentence: "In the electrolysis of water...

Exam 20: Electrochemistry

Determine E°cell for the reaction: MnO4- + 8 H+ + 5 Fe2+ → Mn2+ + 4 H2O + 5 Fe3+. The half reactions are: Fe3+(aq) + e- → Fe2+(aq) E° = +0.771 V MnO4-(aq) + 8 H+(aq) + 5 e- → Mn2+(aq) + 4 H2O(l) E° = 1.507 V

Choose the INCORRECT statement.

3.53 L of 0.362 M CuCl2(aq) solution are electrolyzed for 55.6 minutes with a current of 14.0-amperes. What is [CuCl2] when the electrolysis ends?

What mass of silver can be deposited by the passage of a constant current of 5.00 A through a AgNO3 solution for 2.00 hours?

Consider the cell: Ni ∣ Ni2+ (?M) || Cu2+ (0.136 M) ∣ Cu Ni2+/Ni E° = -0.257 V Cu2+/Cu E° = 0.340 V The measured potential of the cell is 0.621 V. What is [Ni2+] at 25°C?

Zn+2(aq) + 2 e- → Zn(s) E° = -0.763 V

For the reaction: Mg(s) + 2 AgNO3(aq) → 2 Ag(s) + Mg(NO3) 2(aq) Write a voltaic diagram for the reaction.

Determine E°cell for the reaction: 2 Al + 3 Zn2+ → 2 Al3+ + 3 Zn. The half reactions are: Al3+(aq) + 3 e- → Al(s) E° = -1.676 V Zn2+(aq) + 2 e- → Zn(s) E° = -0.763 V

The hydrogen standard electrode is the most convenient standard electrode to use.

Two cells containing solutions of AgNO3 and CuSO4, respectively, were connected in series and electrolyzed. The cathode in the AgNO3 cell was found to gain 1.078 grams in weight. How much had the cathode in the other cell gained?

Find Ecell at 25°C for the following voltaic cell: Cu(s) ∣ Cu2+(aq) (0.10 M) || Cu2+(aq) (0.85 M) ∣ Cu(s) The half-reaction is: Cu2+(aq) + 2 e- → Cu(s) E° = +0.377 volts

Determine E°cell for the reaction: 2 Al3+ + 3 Zn → 2 Al + 3 Zn2+. The half reactions are: Al3+(aq) + 3 e- → Al(s) E° = -1.676 V Zn2+(aq) + 2 e- → Zn(s) E° = -0.763 V

A primary battery is recharged by passing electricity through the battery.

Determine E°cell for the reaction: I2 + Cu → 2 I- + Cu2+. The half reactions are: I2(s) + 2 e- → 2 I-(aq) E° = +0.535 V Cu2+ + 2 e- → Cu E° = 0.340 V

What is the cell diagram for the spontaneous cell involving the Fe3+ ∣ Fe2+ (0.771V) half cell and the Zn2+ ∣ Zn (-0.763 V) half cell?

Choose the INCORRECT statement.

For the cell reaction at 25°C Cu2+(aq) + Zn(s) → Cu(s) + Zn2+(aq) , E°cell = +1.100 V. What is the equilibrium constant for this reaction?

In the electrolysis of water, oxygen is evolved at the cathode.

What is Keq at 25°C of the spontaneous cell made from Ag+/Ag (0.80 V) and Cl2/Cl- (1.36 V) half cells?

Choose the INCORRECT completion of the following sentence: "In the electrolysis of water...

Determine E°cell for the reaction: MnO₄^- + 8 H⁺+ 5 Fe²⁺ → Mn²⁺ + 4 H₂O + 5 Fe³⁺. The half reactions are: Fe³⁺(aq) + e- → Fe²⁺(aq) E° = +0.771 V MnO₄^-(aq) + 8 H⁺(aq) + 5 e- → Mn²⁺(aq) + 4 H₂O(l) E° = 1.507 V

3.53 L of 0.362 M CuCl₂(aq) solution are electrolyzed for 55.6 minutes with a current of 14.0-amperes. What is [CuCl₂] when the electrolysis ends?

What mass of silver can be deposited by the passage of a constant current of 5.00 A through a AgNO₃ solution for 2.00 hours?

Consider the cell: Ni ∣ Ni²⁺ (?M) || Cu²⁺(0.136 M) ∣ Cu Ni²⁺/Ni E° = -0.257 V Cu²⁺/Cu E° = 0.340 V The measured potential of the cell is 0.621 V. What is [Ni²⁺] at 25°C?

For the reaction: Mg(s) + 2 AgNO₃(aq) → 2 Ag(s) + Mg(NO₃) ₂(aq) Write a voltaic diagram for the reaction.

Determine E°cell for the reaction: 2 Al + 3 Zn²⁺ → 2 Al³⁺ + 3 Zn. The half reactions are: Al³⁺(aq) + 3 e- → Al(s) E° = -1.676 V Zn²⁺(aq) + 2 e- → Zn(s) E° = -0.763 V

Two cells containing solutions of AgNO₃ and CuSO₄, respectively, were connected in series and electrolyzed. The cathode in the AgNO₃ cell was found to gain 1.078 grams in weight. How much had the cathode in the other cell gained?

Determine E°cell for the reaction: 2 Al³⁺ + 3 Zn → 2 Al + 3 Zn²⁺. The half reactions are: Al3+(aq) + 3 e- → Al(s) E° = -1.676 V Zn²⁺(aq) + 2 e- → Zn(s) E° = -0.763 V

Determine E°cell for the reaction: I₂ + Cu → 2 I- + Cu²⁺. The half reactions are: I₂(s) + 2 e- → 2 I-(aq) E° = +0.535 V Cu²⁺ + 2 e- → Cu E° = 0.340 V

What is the cell diagram for the spontaneous cell involving the Fe³⁺ ∣ Fe²⁺ (0.771V) half cell and the Zn²⁺ ∣ Zn (-0.763 V) half cell?

For the cell reaction at 25°C Cu²⁺(aq) + Zn(s) → Cu(s) + Zn²⁺(aq) , E°cell = +1.100 V. What is the equilibrium constant for this reaction?

What is Keq at 25°C of the spontaneous cell made from Ag⁺/Ag (0.80 V) and Cl₂/Cl- (1.36 V) half cells?