Question 1

What is Ecell at 25°C of the spontaneous cell made from Ag+/Ag (0.80 V) and Cl2/Cl- (1.36 V) half cells if [Ag+] = 10-2 and [Cl-] = 10-4 with P(Cl2) = 1.1 atm?

Accepted Answer

A)  0.65 V 
B)  0.38 V 
C)  0.74 V 
D)  0.92 V 
E)  0.20 V 
A)  0.65 V 
B)  0.38 V 
C)  0.74 V 
D)  0.92 V 
E)  0.20 V C

Question 2

In the cell Fe2+ ∣ Fe3+ || Cu2+ ∣ Cu which will increase the cell voltage the most?

Accepted Answer

A)  Halve [Cu2+]. 
B)  Halve [Fe2+]. 
C)  Double [Cu2+]. 
D)  Double [Fe2+]. 
E)  Cut Cu electrode in half. 
A)  Halve [Cu2+]. 
B)  Halve [Fe2+]. 
C)  Double [Cu2+]. 
D)  Double [Fe2+]. 
E)  Cut Cu electrode in half. D

Question 3

The active metal is called a sacrificial cathode.

Accepted Answer

A) True 
 B)False  False

Question 4

What is the [H+] in a concentration cell at 25°C if the cell potential is 0.0451 V and cell diagram: Pt ∣ H2 (g, 1 atm) ∣ H+ (?) ‖ H+ (1 M) ∣ H2 (g, 1 atm)
2 H+(aq) + 2 e- → H2(g)  &emsp;  E° = 0. V

Accepted Answer

A)  0.51 M 
B)  0.42 M 
C)  0.030 M 
D)  0.17 M 
E)  5.7 M 
A)  0.51 M 
B)  0.42 M 
C)  0.030 M 
D)  0.17 M 
E)  5.7 M

Question 5

How many coulombs would be needed to deposit all of the Ag+ ion from 600 mL of a solution 0.250 M in Ag+?

Accepted Answer

A)  1.45 × 107 C 
B)  1.56 × 106 C 
C)  1.45 × 104 C 
D)  2.41 × 104 C 
E)  1.56 × 104 C 
A)  1.45 × 107 C 
B)  1.56 × 106 C 
C)  1.45 × 104 C 
D)  2.41 × 104 C 
E)  1.56 × 104 C

Question 6

Given the table below predict the numerical value of the standard cell potential for the reaction: 2 Cr(s) + 3 Cu2+(aq) → 2 Cr3+(aq) + 3 Cu(s)
Half Reaction E° (volts)
(1) Cr3+ + 3 e- → Cr   &emsp; -0.74
(2) Cr3+ + e- → Cr2+   &emsp; -0.41
(3) Cr2O72- + 14 H+ + 6 e- → 2 Cr3+ + 7 H2O   &emsp; 1.33
(4) Cu+ + e- → Cu   &emsp;  0.52
(5) Cu2+ + 2 e- → Cu   &emsp;  0.34
(6) Cu2+ + e- → Cu+   &emsp;  0.16

Accepted Answer

A)  2.50 volts 
B)  0.417 volts 
C)  -1.08 volts 
D)  1.08 volts 
E)  -0.40 volts 
A)  2.50 volts 
B)  0.417 volts 
C)  -1.08 volts 
D)  1.08 volts 
E)  -0.40 volts

Question 7

For the reaction: Mg(s) + AgNO3(aq) → Ag(s) + Mg(NO3)2(aq) Ag+(aq) + e- → Ag(s) E° = 0.800 V
Mg2+(aq) + 2 e- → Mg(s) E° = -2.356 V
Is the reaction spontaneous and why?

Accepted Answer

A)  No, Mg(s) does not react with Ag+. 
B)  No, E° is a positive value. 
C)  No, E° is a negative value. 
D)  Yes, E° is a positive value. 
E)  Yes, E° is a negative value. 
A)  No, Mg(s) does not react with Ag+. 
B)  No, E° is a positive value. 
C)  No, E° is a negative value. 
D)  Yes, E° is a positive value. 
E)  Yes, E° is a negative value.

Question 8

An electrolysis is carried out by passing an electric current through a solution of copper sulfate using inert electrodes. This causes:

Accepted Answer

A)  Cu to plate out on the negative electrode 
B)  Cu to plate out on the anode 
C)  oxygen to form on the negative electrode 
D)  H2 to form at the negative electrode 
E)  sulfur to form on the positive electrode 
A)  Cu to plate out on the negative electrode 
B)  Cu to plate out on the anode 
C)  oxygen to form on the negative electrode 
D)  H2 to form at the negative electrode 
E)  sulfur to form on the positive electrode

Question 9

Determine E°cell at 25°C for the following reaction: 3 Sn2+ + 2 Al(s) → 2 Al3+ + 3 Sn(s)
Al3+ + 3 e- → Al(s)   &emsp; E° = -1.676 V
Sn2+ + 2 e- → Sn(s)   &emsp; E° = -0.137 V

Accepted Answer

A)  2.941 V 
B)  -1.813 V 
C)  1.813 V 
D)  -1.539 V 
E)  1.539 V 
A)  2.941 V 
B)  -1.813 V 
C)  1.813 V 
D)  -1.539 V 
E)  1.539 V

Question 10

E°cell is the standard cell potential.

Accepted Answer

A) True 
 B)False

Question 11

A constant current of 10.0 A is passed through an electrolytic cell for 90.0 min. How many Coulombs of charge are passed through the cell?

Accepted Answer

A)  0.00933 
B)  0.560 
C)  0.00560 
D)  900 
E)  15 
A)  0.00933 
B)  0.560 
C)  0.00560 
D)  900 
E)  15

Question 12

The net reaction in a voltaic cell with E°cell = +0.726 V is, 2 Fe3+(aq) + 3 Zn(S) → 2 Fe(s) + 3 Zn2+(aq)
What is ΔG° for this reaction at 25°C?

Accepted Answer

A)  -210 kJ 
B)  -140 kJ 
C)  -700 kJ 
D)  -463 kJ 
E)  -420 kJ 
A)  -210 kJ 
B)  -140 kJ 
C)  -700 kJ 
D)  -463 kJ 
E)  -420 kJ

Question 13

What is the cell reaction of the spontaneous cell made from the Zn2+/Zn (-0.76 V) and Br2 /2Br-(1.07 V) half cells?

Accepted Answer

A)  2 Br- + Zn2+ → Zn + Br2 
B)  Br2 + Zn → Zn2+ + 2 Br- 
C)  2 Br- + Zn → Br2 + Zn2+ 
D)  Br2 + Zn → Zn2+ + Br- 
E)  Br2 + Zn2+ → Zn + 2Br- 
A)  2 Br- + Zn2+ → Zn + Br2 
B)  Br2 + Zn → Zn2+ + 2 Br- 
C)  2 Br- + Zn → Br2 + Zn2+ 
D)  Br2 + Zn → Zn2+ + Br- 
E)  Br2 + Zn2+ → Zn + 2Br-

Question 14

If the voltage of an electrochemical cell is negative then the cell reaction is:

Accepted Answer

A)  nonspontaneous 
B)  slow 
C)  exothermic 
D)  spontaneous 
E)  fast 
A)  nonspontaneous 
B)  slow 
C)  exothermic 
D)  spontaneous 
E)  fast

Question 15

How long would it take to deposit 15.0 g copper metal at the cathode of an electrolysis cell running with a current of 150 mA?

Accepted Answer

A)  42.2 h 
B)  4.22 h 
C)  12.7 h 
D)  84.4 h 
E)  19.0 h 
A)  42.2 h 
B)  4.22 h 
C)  12.7 h 
D)  84.4 h 
E)  19.0 h

Question 16

What is the Ecell for the following concentration cell at 25°C: Pt ∣ H2 (g, 0.025 atm) ∣ H+ (0.012 M) || H+ (1 M) ∣ H2 (g, 1 atm) ∣ Pt
2 H+(aq) + 2 e- → H2(g)   &emsp;  E° = 0. V

Accepted Answer

A)  -0.16 V 
B)  +0.066 V 
C)  -0.132 V 
D)  0.16 V 
E)  -0.066 V 
A)  -0.16 V 
B)  +0.066 V 
C)  -0.132 V 
D)  0.16 V 
E)  -0.066 V

Question 17

The following galvanic cell has a measured cell potential E°cell = 0.646 V. Pt(s) ∣ Sn4+(aq), Sn2+(aq) || Ag+(aq) ∣ Ag(s) Given that the standard reduction potential for the reduction of Ag+ to Ag(s) is +0.800 V, what is the standard reduction potential for the Sn4+/Sn2+ half-reaction?

Accepted Answer

A)  +0.154 V 
B)  -0.154 V 
C)  +1.45 V 
D)  -1.45 V 
E)  +0.308 V 
A)  +0.154 V 
B)  -0.154 V 
C)  +1.45 V 
D)  -1.45 V 
E)  +0.308 V

Question 18

What is the concentration of Al3+ in the following cell at 25°C if the cell voltage is 1.486 V? Al ∣ Al3+(?) || Sn2+(3.21 × 10-4 M) ∣ Sn
Al3+ + 3 e- → Al(s)  &emsp;  E° = -1.676 V
Sn2+ + 2 e- → Sn(s)  &emsp;  E° = -0.137 V

Accepted Answer

A)  2.8 × 10-3 M 
B)  1.6 × 10-5 M 
C)  4.5 × 10-5 M 
D)  2.4 × 10-2 M 
E)  7.8 × 10-6 M 
A)  2.8 × 10-3 M 
B)  1.6 × 10-5 M 
C)  4.5 × 10-5 M 
D)  2.4 × 10-2 M 
E)  7.8 × 10-6 M

Question 19

Write the net redox reaction that occurs in the galvanic cell. Zn(s) ∣ Zn+2(aq) || Pb+2(aq)∣Pb(s)

Accepted Answer

A)  Pb(s) + Zn(s) → Pb+2(aq) + Zn+2(aq) + 4 e- 
B)  Pb(s) + Zn+2(aq) → Pb+2(aq) + Zn(s) 
C)  Pb+2(s) + Zn+2(s) → Pb(s) + Zn(s) + 4 e- 
D)  Pb+2(aq) + Zn(s) → Zn+2(aq) + Pb(s) 
E)  Pb(s) + Zn(s) + 4 e- → Pb+2(aq) + Zn+2(aq) 
A)  Pb(s) + Zn(s) → Pb+2(aq) + Zn+2(aq) + 4 e- 
B)  Pb(s) + Zn+2(aq) → Pb+2(aq) + Zn(s) 
C)  Pb+2(s) + Zn+2(s) → Pb(s) + Zn(s) + 4 e- 
D)  Pb+2(aq) + Zn(s) → Zn+2(aq) + Pb(s) 
E)  Pb(s) + Zn(s) + 4 e- → Pb+2(aq) + Zn+2(aq)

Question 20

Given the following half-reactions occurring in the silver-zinc hearing aid battery, calculate the voltage at 25°C of this battery.
 ZnO(s) + H2O(l) + 2 e- → Zn(s) + 2 OH-  &emsp;  E° = -1.260 V
Ag2O(s) + H2O(l) + 2 e- → 2 Ag(s) + 2 OH-  &emsp;  E° = +0.342 V

Accepted Answer

A)  +1.602 V 
B)  +1.402 V 
C)  +0.858 V 
D)  -0.858 V 
E)  -1.602 V 
A)  +1.602 V 
B)  +1.402 V 
C)  +0.858 V 
D)  -0.858 V 
E)  -1.602 V

Exam 20: Electrochemistry

What is Ecell at 25°C of the spontaneous cell made from Ag+/Ag (0.80 V) and Cl2/Cl- (1.36 V) half cells if [Ag+] = 10-2 and [Cl-] = 10-4 with P(Cl2) = 1.1 atm?

In the cell Fe2+ ∣ Fe3+ || Cu2+ ∣ Cu which will increase the cell voltage the most?

The active metal is called a sacrificial cathode.

What is the [H+] in a concentration cell at 25°C if the cell potential is 0.0451 V and cell diagram: Pt ∣ H2 (g, 1 atm) ∣ H+ (?) ‖ H+ (1 M) ∣ H2 (g, 1 atm) 2 H+(aq) + 2 e- → H2(g) E° = 0. V

How many coulombs would be needed to deposit all of the Ag+ ion from 600 mL of a solution 0.250 M in Ag+?

For the reaction: Mg(s) + AgNO3(aq) → Ag(s) + Mg(NO3)2(aq) Ag+(aq) + e- → Ag(s) E° = 0.800 V Mg2+(aq) + 2 e- → Mg(s) E° = -2.356 V Is the reaction spontaneous and why?

An electrolysis is carried out by passing an electric current through a solution of copper sulfate using inert electrodes. This causes:

Determine E°cell at 25°C for the following reaction: 3 Sn2+ + 2 Al(s) → 2 Al3+ + 3 Sn(s) Al3+ + 3 e- → Al(s) E° = -1.676 V Sn2+ + 2 e- → Sn(s) E° = -0.137 V

E°cell is the standard cell potential.

A constant current of 10.0 A is passed through an electrolytic cell for 90.0 min. How many Coulombs of charge are passed through the cell?

The net reaction in a voltaic cell with E°cell = +0.726 V is, 2 Fe3+(aq) + 3 Zn(S) → 2 Fe(s) + 3 Zn2+(aq) What is ΔG° for this reaction at 25°C?

What is the cell reaction of the spontaneous cell made from the Zn2+/Zn (-0.76 V) and Br2 /2Br-(1.07 V) half cells?

If the voltage of an electrochemical cell is negative then the cell reaction is:

How long would it take to deposit 15.0 g copper metal at the cathode of an electrolysis cell running with a current of 150 mA?

What is the Ecell for the following concentration cell at 25°C: Pt ∣ H2 (g, 0.025 atm) ∣ H+ (0.012 M) || H+ (1 M) ∣ H2 (g, 1 atm) ∣ Pt 2 H+(aq) + 2 e- → H2(g) E° = 0. V

The following galvanic cell has a measured cell potential E°cell = 0.646 V. Pt(s) ∣ Sn4+(aq), Sn2+(aq) || Ag+(aq) ∣ Ag(s) Given that the standard reduction potential for the reduction of Ag+ to Ag(s) is +0.800 V, what is the standard reduction potential for the Sn4+/Sn2+ half-reaction?

What is the concentration of Al3+ in the following cell at 25°C if the cell voltage is 1.486 V? Al ∣ Al3+(?) || Sn2+(3.21 × 10-4 M) ∣ Sn Al3+ + 3 e- → Al(s) E° = -1.676 V Sn2+ + 2 e- → Sn(s) E° = -0.137 V

Write the net redox reaction that occurs in the galvanic cell. Zn(s) ∣ Zn+2(aq) || Pb+2(aq)∣Pb(s)

Given the following half-reactions occurring in the silver-zinc hearing aid battery, calculate the voltage at 25°C of this battery. ZnO(s) + H2O(l) + 2 e- → Zn(s) + 2 OH- E° = -1.260 V Ag2O(s) + H2O(l) + 2 e- → 2 Ag(s) + 2 OH- E° = +0.342 V

Matter - Its Properties and Measurement

Atoms and the Atomic Theory

Chemical Compounds

Chemical Reactions

Introduction to Reactions in Aqueous Solutions

Gases

Thermochemistry

Electrons in Atoms

The Periodic Table and Some Atomic Properties

Chemical Bonding I: Basic Concepts

Chemical Bonding II: Additional Aspects

Intermolecular Forces: Liquids and Solids

Solutions and Their Physical Properties

Chemical Kinetics

Principles of Chemical Equilibrium

Acids and Bases

Additional Aspects of Acid-Base Equilibria

Solubility and Complex-Ion Equilibria

Spontaneous Change: Entropy and Free Energy

Main Group Elements I: Groups 1, 2, 13, and 14

Main Group Elements II: Groups 18, 17, 16, 15, and Hydrogen

The Transition Elements

Complex Ions and Coordination Compounds

Nuclear Chemistry 1-41

Structures of Organic Compounds

Reactions of Organic Compounds

Chemistry of the Living State

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What is Ecell at 25°C of the spontaneous cell made from Ag⁺/Ag (0.80 V) and Cl₂/Cl- (1.36 V) half cells if [Ag⁺] = 10^-2 and [Cl-] = 10^-4 with P(Cl₂) = 1.1 atm?

In the cell Fe²⁺ ∣ Fe³⁺ || Cu²⁺ ∣ Cu which will increase the cell voltage the most?

What is the [H⁺] in a concentration cell at 25°C if the cell potential is 0.0451 V and cell diagram: Pt ∣ H₂ (g, 1 atm) ∣ H⁺ (?) ‖ H⁺ (1 M) ∣ H₂ (g, 1 atm) 2 H⁺(aq) + 2 e- → H₂(g) E° = 0. V

For the reaction: Mg(s) + AgNO₃(aq) → Ag(s) + Mg(NO₃)₂(aq) Ag+(aq) + e- → Ag(s) E° = 0.800 V Mg₂+(aq) + 2 e- → Mg(s) E° = -2.356 V Is the reaction spontaneous and why?

Determine E°cell at 25°C for the following reaction: 3 Sn²⁺ + 2 Al(s) → 2 Al³⁺ + 3 Sn(s) Al³⁺ + 3 e- → Al(s) E° = -1.676 V Sn²⁺ + 2 e- → Sn(s) E° = -0.137 V

The net reaction in a voltaic cell with E°cell = +0.726 V is, 2 Fe³⁺(aq) + 3 Zn(S) → 2 Fe(s) + 3 Zn²⁺(aq) What is ΔG° for this reaction at 25°C?

What is the cell reaction of the spontaneous cell made from the Zn²⁺/Zn (-0.76 V) and Br₂ /2Br-(1.07 V) half cells?

What is the Ecell for the following concentration cell at 25°C: Pt ∣ H₂(g, 0.025 atm) ∣ H⁺ (0.012 M) || H⁺ (1 M) ∣ H₂ (g, 1 atm) ∣ Pt 2 H⁺(aq) + 2 e- → H₂(g) E° = 0. V

What is the concentration of Al³⁺ in the following cell at 25°C if the cell voltage is 1.486 V? Al ∣ Al³⁺(?) || Sn²⁺(3.21 × 10^-4 M) ∣ Sn Al³⁺ + 3 e- → Al(s) E° = -1.676 V Sn²⁺ + 2 e- → Sn(s) E° = -0.137 V

Given the following half-reactions occurring in the silver-zinc hearing aid battery, calculate the voltage at 25°C of this battery. ZnO(s) + H₂O(l) + 2 e- → Zn(s) + 2 OH^- E° = -1.260 V Ag₂O(s) + H₂O(l) + 2 e- → 2 Ag(s) + 2 OH^- E° = +0.342 V