Question 1

Calculate Ecell for the following electrochemical cell at 25°C. The standard cell potential, E°cell, is 0.460 V. Cu(s) | Cu2+(aq, 0.016 M) || Ag+(aq, 0.11 M) | Ag(s)
​

Accepted Answer

A)  0.456 V 
B)  0.282 V 
C)  0.460 V 
D)  0.485 V 
E)  0.452 V

Question 2

Write a balanced net ionic equation for the overall reaction represented by the following cell notation. 
Al(s) | Al3+(aq) || Cl2(g) | Cl-(aq) | Pt(s)

Accepted Answer

A)  2 Al(s) + 3 Cl2(g) → 2 Al3+(aq) + 6 Cl-(aq) 
B)  Al(s) + Al3+(aq) → Cl-(aq) + Cl2(g) 
C)  2 Al3+(aq) + 6 Cl-(aq) → 2 Al(s) + 3 Cl2(g) 
D)  Al(s) + 3 Cl2(g) → Al3+(s) + 2 Cl-(aq) 
E)  Al(s) + 2 Cl-(aq) → Cl2(g) + Al3+(aq)

Question 3

Calculate $E _ { \text {cell } } ^ { \circ }$ for the electrochemical cell Pb(s) |PbCl2(s) | Cl-(aq, 1.0 M) || Fe3+(aq, 1.0 M), Fe2+(aq, 1.0 M) | Pt(s). The standard reduction potentials are as follows:
Pb2+(aq) + 2 e- ? Pb(s)
E° = -0.126 V
PbCl2(s) + 2 e- ? Pb(s) + 2 Cl-(aq)
E° = -0.267 V
Fe3+(aq) + e- ? Fe2+(aq)
E° = +0.771 V
Fe2+(aq) + e- ? Fe(s)
E° = -0.44 V

Accepted Answer

A)  -0.504 V 
B)  -0.062 V 
C)  +0.504 V 
D)  +1.038 V 
E)  +1.604 V

Question 4

Write balanced reduction and oxidation half-reactions for the processes that occur at the cathode and anode of a fuel cell used in NASA's space shuttles.

Accepted Answer

The answer of Write balanced reduction and oxidation half-reactions for...

Question 5

An SHE electrode has been assigned a standard reduction potential, E°, of 0.00 volts. Which of the following reactions will occur at this electrode?

Accepted Answer

A)  2 H2O( $\ell$ ) + 2 e- ?H2(g) + 2 OH-(aq) 
B)  O2(g) + 4 e- ? 2 O2-(aq) 
C)  Hg2Cl2(s) + 2 e- ? 2 Hg( $\ell$ ) + 2 Cl-(aq) 
D)  Li+(aq) + e- ? Li(s) 
E)  2 H+(aq) + 2 e- ? H2(g)

Question 6

If an electric current is passed through a solution of molten potassium bromide, KBr, the product at the cathode is _____.

Accepted Answer

The answer of If an electric current is passed through...

Question 7

One Faraday is defined as the:

Accepted Answer

A)  charge on a single electron. 
B)  quantity of electric charge carried by one mole of electrons. 
C)  voltage required to reduce one mole of reactant. 
D)  number of moles of electrons required to reduce one mole of a reactant. 
E)  charge passed by one ampere of current in one second.

Question 8

Balance the following oxidation-reduction reaction occurring in an acidic solution. 
MnO4-(aq) + Cr2+(aq) → Mn2+(aq) + Cr3+(aq)

Accepted Answer

A)  MnO4-(aq) + 8 H+(aq) + 5 Cr2+(aq) → Mn2+(aq) + 4 H2O(l) + 5 Cr3+(aq) 
B)  MnO4-(aq) + 8 H+(aq) + Cr2+(aq) → Mn2+(aq) + 4 H2O(l) + Cr3+(aq) 
C)  MnO4-(aq) + 4 H2(g) + 5 Cr2+(aq)→ Mn2+(aq) + 4 H2O(l) + 5 Cr3+(aq) 
D)  MnO4-(aq) + 8 H+(aq) + 2 Cr2+(aq) → Mn2+(aq) + 4 H2O(l) + 2 Cr3+(aq) 
E)  MnO4-(aq) + Cr2+(aq) → Mn2+(aq) + 2 O2(g) + Cr3+(aq)

Question 9

A current of 12.0 A is passed through molten magnesium chloride for 14.0 h. How many moles of magnesium metal can be produced from this electrolysis?

Accepted Answer

A)  0.0522 mol 
B)  3.13 mol 
C)  0.37 mol 
D)  0.22 mol 
E)  6.27 mol

Question 10

The standard reduction potentials for a reaction are as follows: 
Pb2+(aq) + 2 e- ? Pb(s)
E° = -0.126 V
PbSO4(s) + 2 e- ? Pb(s) + SO42-(aq)
E° = -0.355 V
Calculate the Ksp for lead(II)sulfate (PbSO4) at 25 °C.

Accepted Answer

A)  3.4 × 10-28 
B)  1.8 × 10-8 
C)  5.6 × 10-5 
D)  5.6 × 107 
E)  2.9 × 1037

Question 11

Given the following two half-reactions, write the overall reaction in the direction in which it is product-favored, and calculate the standard cell potential. 
Pb2+(aq) + 2 e- ? Pb(s)
E° = -0.126 V
Fe3+(aq) + e- ? Fe2+(s)
E° = +0.771 V

Accepted Answer

A)  Pb2+(aq) + 2 Fe2+(s) ? Pb(s) + 2 Fe3+(aq); $E _ { \text {cell } } ^ { \circ }$ = +0.897 V 
B)  Pb2+(aq) + Fe2+(s) ? Pb(s) + Fe3+(aq); $E _ { \text {cell } } ^ { \circ }$ = +0.645 V 
C)  Pb(s) + 2 Fe3+(aq) ? Pb2+(aq) + 2 Fe2+(s); $E _ { \text {cell } } ^ { \circ }$ = +1.416 V 
D)  Pb(s) + 2 Fe3+(aq) ? Pb2+(aq) + 2 Fe2+(s); $E _ { \text {cell } } ^ { \circ }$ = +0.897 V 
E)  Pb(s) + Fe3+(aq) ? Pb2+(aq) + Fe2+(s); $E _ { \text {cell } } ^ { \circ }$ = +0.645 V

Question 12

The unit for electromotive force, emf, is the volt. 1 volt is equal to _____.

Accepted Answer

A)  one joule per second 
B)  one coulomb per joule 
C)  one joule per coulomb 
D)  one coulomb per second 
E)  one calorie per second

Question 13

Calculate the standard cell potential ( $E _ { \text {cell } } ^ { \circ }$ ) for the reaction 2 Ag(s) + Co2+(aq) ? 2 Ag+(aq) + Co(s). The standard reduction potentials are as follows:
Ag+(aq) + e-? Ag(s)
E° = 0.8 V
Co2+(aq) +2 e-? Co(s)
E° = -0.277 V

Accepted Answer

A)  -1.077 V 
B)  1.077 V 
C)  -1.877 V 
D)  1.877 V 
E)  1.323 V

Question 14

Calculate the equilibrium constant for the following reaction at 25 °C, 2 IO3-(aq) + 5 Hg( $\ell$ ) + 12 H+(aq) ? I2(s) + 5 Hg2+(aq) + 6 H2O( $\ell$ )
The standard reduction potentials are as follows:
IO3-(aq) + 6 H+(aq) + 5 e- ? I2(s) + 3 H2O( $\ell$ )
E° = +1.20 V
Hg2+(aq) + 2 e- ? Hg( $\ell$ )
E° = +0.86 V

Accepted Answer

A)  3 × 10-58 
B)  6 × 105 
C)  3 × 1011 
D)  6 × 1028 
E)  3 × 1057

Question 15

In the given electrochemical cell, which of the following is the cathode half-reaction? 
Zn(s) | Zn2+(aq) || Fe3+(aq), Fe2+(aq) | Pt(s)

Accepted Answer

A)  Fe3+(aq) + e− → Fe2+(aq) 
B)  Fe2+(aq) + e− → Fe3+(aq) 
C)  Fe2+(aq) + Pt(s) → Fe3+(aq) + e− 
D)  Zn2+(aq) → Zn(s) + 2 e− 
E)  Zn(s) → Zn2+(aq) + 2 e−

Question 16

When the following oxidation-reduction reaction in acidic solution is balanced, what is the lowest whole-number coefficient for Na+(aq) ion? 
Na(s) + Ca2+(aq) → Na+(aq) + Ca(s)

Accepted Answer

A)  5 
B)  4 
C)  1 
D)  3 
E)  2

Question 17

Write a balanced half-reaction for the reduction of CrO42-(aq) to Cr(OH)3(s) in a basic solution.

Accepted Answer

A)  CrO42-(aq) + 3 OH-(aq) + 3 e- ? Cr(OH)3(s) + 2 O2(g) 
B)  CrO42-(aq) + 3 H+(aq) + 3 e- ? Cr(OH)3(s) 
C)  CrO42-(aq) + 3 H+(aq) ? Cr(OH)3(s) + 2 e- 
D)  CrO42-(aq) + 4 H2O( $\ell$ ) + 3 e- ? Cr(OH)3(s) + 5 OH-(aq) 
E)  CrO42-(aq) + 3 OH-(aq) ? Cr(OH)3(s) + 2 O2(g)

Question 18

Balance the following half-reaction occurring in a basic solution. 
MnO2(s) → Mn(OH)2(s)

Accepted Answer

A)  MnO2(s) + 2 H2O(l) + 2e−→ Mn(OH)2(s)+ 2 OH−(aq) 
B)  MnO2(s) + 2 H2O(l) + 4e−→ Mn(OH)2(s)+ (OH)2−(aq) 
C)  MnO2(s) + H22+(aq) + 2e−→ Mn(OH)2(s) 
D)  MnO2(s) + H2(g) → Mn(OH)2(s) + 2 e− 
E)  MnO2(s) + 2 H2O(l) → Mn(OH)2(s)+ 2 OH−(aq)

Question 19

For the electrochemical cell Cu(s) | Cu2+ || Ag+ | Ag(s), the standard cell potential is 0.46 V. A cell using these reagents was made, and the observed potential was 0.26 V at 25 oC. Which of the following is a possible explanation for the observed voltage?

Accepted Answer

A)  The volume of the Cu2+ solution was larger than the volume of the Ag+ solution. 
B)  The volume of the Ag+ solution was larger than the volume of the Cu2+ solution. 
C)  The Cu2+ concentration was larger than the Ag+ concentration. 
D)  The Ag electrode was twice as large as the Cu electrode. 
E)  The Ag+ concentration was larger than the Cu2+ concentration.

Question 20

Calculate the cell potential at 25 °C for the following overall reaction. Zn2+(aq) + 2 Fe2+(aq) → Zn(s) + 2 Fe3+(aq)
[Zn2+] = 1.50 × 10-4 M, [Fe3+] = 0.0200 M, and [Fe2+] = 0.0100 M. The standard reduction potentials are as follows:
Zn2+(aq) + 2 e- → Zn(s)
E° = -0.763 V
Fe3+(aq) + e- → Fe2+(aq)
E° = +0.771 V

Accepted Answer

A)  -1.665 V 
B)  -1.534 V 
C)  -1.439 V 
D)  -0.008 V 
E)  +0.008 V

Exam 20: Principles of Chemical Reactivity: Electron Transfer Reactions

Calculate E_cell for the following electrochemical cell at 25°C. The standard cell potential, E°_cell, is 0.460 V. Cu(s) | Cu²⁺(aq, 0.016 M) || Ag⁺(aq, 0.11 M) | Ag(s)

Write a balanced net ionic equation for the overall reaction represented by the following cell notation. Al(s) | Al³⁺(aq) || Cl₂(g) | Cl-(aq) | Pt(s)

Write balanced reduction and oxidation half-reactions for the processes that occur at the cathode and anode of a fuel cell used in NASA's space shuttles.

An SHE electrode has been assigned a standard reduction potential, E°, of 0.00 volts. Which of the following reactions will occur at this electrode?

If an electric current is passed through a solution of molten potassium bromide, KBr, the product at the cathode is _____.

One Faraday is defined as the:

Balance the following oxidation-reduction reaction occurring in an acidic solution. MnO₄^-(aq) + Cr²⁺(aq) → Mn²⁺(aq) + Cr³⁺(aq)

A current of 12.0 A is passed through molten magnesium chloride for 14.0 h. How many moles of magnesium metal can be produced from this electrolysis?

The standard reduction potentials for a reaction are as follows: Pb²⁺(aq) + 2 e^- ? Pb(s) E° = -0.126 V PbSO₄(s) + 2 e^- ? Pb(s) + SO₄^2-(aq) E° = -0.355 V Calculate the K_sp for lead(II) sulfate (PbSO₄) at 25 °C.

Given the following two half-reactions, write the overall reaction in the direction in which it is product-favored, and calculate the standard cell potential. Pb²⁺(aq) + 2 e^- ? Pb(s) E° = -0.126 V Fe³⁺(aq) + e^- ? Fe²⁺(s) E° = +0.771 V

The unit for electromotive force, emf, is the volt. 1 volt is equal to _____.

Calculate the standard cell potential ( $E _ { \text {cell } } ^ { \circ }$ ) for the reaction 2 Ag(s) + Co²⁺(aq) ? 2 Ag⁺(aq) + Co(s) . The standard reduction potentials are as follows: Ag⁺(aq) + e^-? Ag(s) E° = 0.8 V Co²⁺(aq) +2 e^-? Co(s) E° = -0.277 V

In the given electrochemical cell, which of the following is the cathode half-reaction? Zn(s) | Zn²⁺(aq) || Fe³⁺(aq) , Fe²⁺(aq) | Pt(s)

When the following oxidation-reduction reaction in acidic solution is balanced, what is the lowest whole-number coefficient for Na⁺(aq) ion? Na(s) + Ca²⁺(aq) → Na⁺(aq) + Ca(s)

Write a balanced half-reaction for the reduction of CrO₄^2-(aq) to Cr(OH) ₃(s) in a basic solution.

Balance the following half-reaction occurring in a basic solution. MnO₂(s) → Mn(OH) ₂(s)

For the electrochemical cell Cu(s) | Cu²⁺ || Ag⁺ | Ag(s) , the standard cell potential is 0.46 V. A cell using these reagents was made, and the observed potential was 0.26 V at 25 ^oC. Which of the following is a possible explanation for the observed voltage?

Exam 20: Principles of Chemical Reactivity: Electron Transfer Reactions

Calculate Ecell for the following electrochemical cell at 25°C. The standard cell potential, E°cell, is 0.460 V. Cu(s) | Cu2+(aq, 0.016 M) || Ag+(aq, 0.11 M) | Ag(s) ​

Write a balanced net ionic equation for the overall reaction represented by the following cell notation. Al(s) | Al3+(aq) || Cl2(g) | Cl-(aq) | Pt(s)

Write balanced reduction and oxidation half-reactions for the processes that occur at the cathode and anode of a fuel cell used in NASA's space shuttles.

An SHE electrode has been assigned a standard reduction potential, E°, of 0.00 volts. Which of the following reactions will occur at this electrode?

If an electric current is passed through a solution of molten potassium bromide, KBr, the product at the cathode is _____.

One Faraday is defined as the:

Balance the following oxidation-reduction reaction occurring in an acidic solution. MnO4-(aq) + Cr2+(aq) → Mn2+(aq) + Cr3+(aq)

A current of 12.0 A is passed through molten magnesium chloride for 14.0 h. How many moles of magnesium metal can be produced from this electrolysis?

The standard reduction potentials for a reaction are as follows: Pb2+(aq) + 2 e- ? Pb(s) E° = -0.126 V PbSO4(s) + 2 e- ? Pb(s) + SO42-(aq) E° = -0.355 V Calculate the Ksp for lead(II) sulfate (PbSO4) at 25 °C.

Given the following two half-reactions, write the overall reaction in the direction in which it is product-favored, and calculate the standard cell potential. Pb2+(aq) + 2 e- ? Pb(s) E° = -0.126 V Fe3+(aq) + e- ? Fe2+(s) E° = +0.771 V

The unit for electromotive force, emf, is the volt. 1 volt is equal to _____.

Calculate the standard cell potential ( Ecell ∘E _ { \text {cell } } ^ { \circ }Ecell ∘​ ) for the reaction 2 Ag(s) + Co2+(aq) ? 2 Ag+(aq) + Co(s) . The standard reduction potentials are as follows: Ag+(aq) + e-? Ag(s) E° = 0.8 V Co2+(aq) +2 e-? Co(s) E° = -0.277 V

In the given electrochemical cell, which of the following is the cathode half-reaction? Zn(s) | Zn2+(aq) || Fe3+(aq) , Fe2+(aq) | Pt(s)

When the following oxidation-reduction reaction in acidic solution is balanced, what is the lowest whole-number coefficient for Na+(aq) ion? Na(s) + Ca2+(aq) → Na+(aq) + Ca(s)

Write a balanced half-reaction for the reduction of CrO42-(aq) to Cr(OH) 3(s) in a basic solution.

Balance the following half-reaction occurring in a basic solution. MnO2(s) → Mn(OH) 2(s)

For the electrochemical cell Cu(s) | Cu2+ || Ag+ | Ag(s) , the standard cell potential is 0.46 V. A cell using these reagents was made, and the observed potential was 0.26 V at 25 oC. Which of the following is a possible explanation for the observed voltage?

Calculate E_cell for the following electrochemical cell at 25°C. The standard cell potential, E°_cell, is 0.460 V. Cu(s) | Cu²⁺(aq, 0.016 M) || Ag⁺(aq, 0.11 M) | Ag(s)

Write a balanced net ionic equation for the overall reaction represented by the following cell notation. Al(s) | Al³⁺(aq) || Cl₂(g) | Cl-(aq) | Pt(s)

Balance the following oxidation-reduction reaction occurring in an acidic solution. MnO₄^-(aq) + Cr²⁺(aq) → Mn²⁺(aq) + Cr³⁺(aq)

The standard reduction potentials for a reaction are as follows: Pb²⁺(aq) + 2 e^- ? Pb(s) E° = -0.126 V PbSO₄(s) + 2 e^- ? Pb(s) + SO₄^2-(aq) E° = -0.355 V Calculate the K_sp for lead(II) sulfate (PbSO₄) at 25 °C.

Given the following two half-reactions, write the overall reaction in the direction in which it is product-favored, and calculate the standard cell potential. Pb²⁺(aq) + 2 e^- ? Pb(s) E° = -0.126 V Fe³⁺(aq) + e^- ? Fe²⁺(s) E° = +0.771 V

Calculate the standard cell potential ( $E _ { \text {cell } } ^ { \circ }$ ) for the reaction 2 Ag(s) + Co²⁺(aq) ? 2 Ag⁺(aq) + Co(s) . The standard reduction potentials are as follows: Ag⁺(aq) + e^-? Ag(s) E° = 0.8 V Co²⁺(aq) +2 e^-? Co(s) E° = -0.277 V

In the given electrochemical cell, which of the following is the cathode half-reaction? Zn(s) | Zn²⁺(aq) || Fe³⁺(aq) , Fe²⁺(aq) | Pt(s)

When the following oxidation-reduction reaction in acidic solution is balanced, what is the lowest whole-number coefficient for Na⁺(aq) ion? Na(s) + Ca²⁺(aq) → Na⁺(aq) + Ca(s)

Write a balanced half-reaction for the reduction of CrO₄^2-(aq) to Cr(OH) ₃(s) in a basic solution.

Balance the following half-reaction occurring in a basic solution. MnO₂(s) → Mn(OH) ₂(s)

For the electrochemical cell Cu(s) | Cu²⁺ || Ag⁺ | Ag(s) , the standard cell potential is 0.46 V. A cell using these reagents was made, and the observed potential was 0.26 V at 25 ^oC. Which of the following is a possible explanation for the observed voltage?