Question 1

Which of the following statements is true concerning the electrochemical cell Zn(s) | Zn2+(aq, 1.0 M) || Ca2+(aq, 1.0 M) | Ca(s) The standard reduction potentials are given follows:
Zn2+(aq) + 2 e− → Zn(s); E° = -0.76 V
Ca2+(aq) + 2 e− → Ca(s); E° = -2.87 V

Accepted Answer

A)  The standard cell potential is -3.63 V. 
B)  The standard cell potential is -2.11 V. 
C)  The standard cell potential is -2.11 V.. 
D)  The standard cell potential is -3.63 V.. 
E)  The standard cell potential is 2.11 V.

Question 2

Which of the following statements is true concerning the voltaic cell shown below?

Accepted Answer

A)  The Zn anode mass decreases as the cell discharges. 
B)  The Zn cathode mass increases as the cell discharges. 
C)  The Zn cathode mass decreases as the cell discharges. 
D)  The Zn anode mass increases as the cell discharges. 
E)  The mass of the Zn electrode neither increases nor decreases as the cell discharges.

Question 3

Which of the following is true for a product-favored reaction at equilibrium?

Accepted Answer

A)  ΔrG° cell > 0 
B)  ΔrG° > 0; E°cell rG° cell rG° > 0; E°cell > 0 
E)  ΔrG° > 0; E°cell = 0

Question 4

Write a balanced half-reaction for the reduction of hydrogen peroxide to water in an acidic solution.

Accepted Answer

A)  2 H2O2( $\ell$ ) ? 2 H2O( $\ell$ ) + O2(g) 
B)  2 H2O2( $\ell$ ) + 2e- ? 2 H2O( $\ell$ ) + O2(g) 
C)  H2O2( $\ell$ ) + 2 H+(aq) + 2 e- ? 2 H2O( $\ell$ ) 
D)  H2O2( $\ell$ ) + 4 H+(aq) + 2 e- ? 2 H2O( $\ell$ ) + H2(g) 
E)  H2O2( $\ell$ ) + 2 H+(aq) + 4 e- ? 2 H2(g) + O2(g)

Question 5

For the following cell reaction, the standard cell potential is 1.34 V. To determine the cell potential at nonstandard conditions, what is the value that should be used for n in the Nernst equation? $$2 \mathrm { MnO } _ { 4 } ^ { - } ( \mathrm { aq } ) + 5 \mathrm { H } _ { 2 } \mathrm { SO } _ { 3 } ( \mathrm { aq } ) \rightarrow 2 \mathrm { Mn } ^ { 2 + } ( \mathrm { aq } ) + 5 \mathrm { SO } _ { 4 } ^ { 2 - } ( \mathrm { aq } ) + 4 \mathrm { H } ^ { + } ( \mathrm { aq } ) + 3 \mathrm { H } _ { 2 } \mathrm { O } ( \mathrm { l } )$$

Accepted Answer

A)  8 
B)  10 
C)  5 
D)  2 
E)  6

Question 6

Calculate ΔrG° for the disproportionation reaction of copper(I) ion (Cu+) at 25 °C. 2 Cu+(aq) → Cu2+(aq) + Cu(s)
The standard reduction potentials are as follows:
Cu+(aq) + e- → Cu(s)
E° = +0.518 V
Cu2+(aq) + 2 e- → Cu(s)
E° = +0.337 V

Accepted Answer

A)  -165 kJ/mol⋅rxn 
B)  -135 kJ/mol⋅rxn 
C)  -34.9 kJ/mol⋅rxn 
D)  +17.5 kJ/mol⋅rxn 
E)  +135 kJ/mol⋅rxn

Question 7

Which of the following statements concerning voltaic cells is not true?

Accepted Answer

A)  A salt bridge allows cations and anions to move between half-cells. 
B)  Electrons flow from a cathode to an anode in the external circuit. 
C)  Oxidation occurs at an anode. 
D)  A voltaic cell can be used as a source of energy. 
E)  A voltaic cell consists of two half-cells.

Question 8

Which of the following is the cell notation for a cell in which the hydrogen electrode is the anode and the cathode half-reaction is 
Co3+(aq) + e− → Co2+(aq)?

Accepted Answer

A)  Pt(s) | H2(g) | H+(aq) || Co3+(aq), Co2+(aq) | Pt(s) 
B)  Pt(s) | H2(g) | H+(aq) || Co3+(aq), Co2+(aq) 
C)  Co2+(aq), Co3+(aq) || H+(aq) | H2(g) | Pt(s) 
D)  Pt(s)| Co2+(aq), Co3+(aq) || H+(aq) | H2(g) | Pt(s) 
E)  H2(g) | H+(aq) || Co2+(aq), Co3+(aq)

Question 9

The standard reduction potentials are as follows: Cr3+(aq) + 3 e- → Cr(s); E° = -0.74 V
Fe2+(aq) + 2 e- → Fe(s); E° = -0.41 V
Calculate the standard Gibbs free energy change for the following reaction.
2 Cr(s) + 3 Fe2+ → 3 Fe(s) + 2 Cr3+(aq)

Accepted Answer

A)  191 kJ 
B)  63.7 kJ 
C)  -504 kJ 
D)  -191 kJ 
E)  1060 kJ

Question 10

Balance the following half-reaction occurring in an acidic solution. 
NO3-(aq) → NO(aq)

Accepted Answer

A)  NO3-(aq) + 4 H+(aq) + 3 e− → NO(g) + 2 H2O(l) 
B)  NO3-(aq) + 2 H2O(l) + 3 e− → NO(g) + 4 H+(aq) 
C)  NO3-(aq) + 4 H+(aq) → NO(g) + 2 H2O(l) + 3 e− 
D)  NO3-(aq) + 3 e− → NO(g) + 4 H+(aq) + 2 H2O(l) 
E)  NO3-(aq) + 4 H+(aq)→ NO(g) + 2 H2O(l)

Question 11

Batteries used in watches contain mercury(II) oxide. As the current flows, mercury(II) oxide is reduced to mercury according to the following reaction: HgO(s) + H2O( $\ell$ ) + 2 e- ? Hg( $\ell$ ) + 2 OH-(aq)
If 2.3 × 10-5 amperes flows continuously for 1200 days, calculate the mass of mercury, Hg( $\ell$ ), produced.

Accepted Answer

A)  2.5 g 
B)  5.0 g 
C)  9.9 g 
D)  13 g 
E)  15 g

Question 12

The standard cell potential of the given electrochemical cell is 0.19 V. Pt | Sn4+(aq, 1.0 M), Sn2+(aq, 1.0 M) || Cu2+(aq, 0.200 M) | Cu
Which of the following factors will increase the measured cell potential of the given electrochemical cell?

Accepted Answer

A)  Switching from a platinum to a graphite anode 
B)  Increasing the size of the anode 
C)  Decreasing the concentration of Cu2+ 
D)  Increasing the concentration of Sn4+ 
E)  Decreasing the temperature of the cell

Question 13

According to the cell notation below, which of the following species is undergoing reduction? 
Ni | Ni2+(aq) || Mn2+(aq) | MnO2(s) | Pt(s)

Accepted Answer

A)  Mn2+(aq) 
B)  Ni2+(aq) 
C)  Ni(s) 
D)  MnO2(s) 
E)  Pt(s)

Question 14

What half-reaction occurs at the cathode during the electrolysis of molten potassium bromide?

Accepted Answer

A)  K(s) → K+(l) + e- 
B)  Br2(l) + 2 e- → 2 Br-(l) 
C)  2 Br-(l) → Br2(l) + 2 e- 
D)  2 K+(l) + 2 e- → 2 K(l) 
E)  2 H2O(l) + 2 e- → H2(g) + 2 OH-(l)

Question 15

If ?rG° for the following reaction is -22.2 kJ/mol-rxn, calculate $E _ { \text {cell } } ^ { \circ }$ for the following reaction: Cu2+(aq) + 2 Ag(s) + 2 Cl-(aq) ? Cu(s) + 2 AgCl(s)

Accepted Answer

A)  -0.460 V 
B)  -0.115 V 
C)  +0.115 V 
D)  +0.230 V 
E)  +0.559 V

Question 16

The cell potential of the following electrochemical cell is determined by using an unspecified concentration of acid. Calculate the pH of the acid solution, given that the measured cell potential is -0.431 V and the anode reduction potential (E°) is 0.222 V at 25 °C. ​
Ag(s) | AgCl(s) | Cl−(aq, 1.0 M) || H+(aq) | H2(g, 1.0 atm) | Pt(s)
​

Accepted Answer

A)  3.53 
B)  11.0 
C)  4.03 
D)  7.06 
E)  3.47

Question 17

Calculate Ecell for the following electrochemical cell at 25 °C Pt(s) | H2(g, 1.00 atm) | H+(aq, 1.00 M) || Sn2+(aq, 0.350 M), Sn4+(aq, 0.020 M) | Pt(s)
The standard reduction potentials are as follows:
Sn4+(aq) + 2 e- → Sn2+(s)
E° = +0.15 V
2 H+(aq) + 2 e- → H2(g)
E° = 0.00 V

Accepted Answer

A)  -0.19 V 
B)  +0.08 V 
C)  +0.11 V 
D)  +0.19 V 
E)  +0.22 V

Question 18

The use of electrical energy to produce chemical change is known as _____. An example of this process is the reduction of sodium chloride, NaCl( $\ell$ ), to produce solid sodium.

Accepted Answer

The answer of The use of electrical energy to produce...

Question 19

Which of the following statements is true for the following reaction, assuming the given reaction proceeds in the forward direction? 
Fe3+(aq) + Co(s) → Fe2+(aq) + Co2+(aq)

Accepted Answer

A)  Fe3+(aq) is oxidized and Co(s) is reduced. 
B)  Fe3+(aq) is oxidized and Co2+(aq) is reduced. 
C)  Co(s) is oxidized and Fe3+(aq) is reduced. 
D)  Co(s) is oxidized and Co2+(aq) is reduced. 
E)  Fe2+(aq) is oxidized and Co(s) is reduced.

Question 20

Which of the following equations represents the Nernst equation?

Accepted Answer

A)  $E = E ^ { \circ } - \left( \frac { R T } { n F } \right) \ln Q$ 
B)  $E = E ^ { \circ } + \log \left( \frac { R T } { n F } \right)$ 
C)  $E = E ^ { \circ } - \left( \frac { R T } { n F } \right) \log Q$ 
D)  $E ^ { \circ } = E - \left( \frac { R T } { n F } \right) \ln Q$ 
E)  $E = E ^ { \circ } - \left( \frac { n F } { R T } \right) \ln Q$

Exam 20: Principles of Chemical Reactivity: Electron Transfer Reactions

Which of the following statements is true concerning the electrochemical cell Zn(s) | Zn²⁺(aq, 1.0 M) || Ca²⁺(aq, 1.0 M) | Ca(s) The standard reduction potentials are given follows: Zn²⁺(aq) + 2 e− → Zn(s) ; E° = -0.76 V Ca²⁺(aq) + 2 e− → Ca(s) ; E° = -2.87 V

Which of the following statements is true concerning the voltaic cell shown below?

Which of the following is true for a product-favored reaction at equilibrium?

Write a balanced half-reaction for the reduction of hydrogen peroxide to water in an acidic solution.

Calculate Δ_rG° for the disproportionation reaction of copper(I) ion (Cu⁺) at 25 °C. 2 Cu⁺(aq) → Cu²⁺(aq) + Cu(s) The standard reduction potentials are as follows: Cu⁺(aq) + e^- → Cu(s) E° = +0.518 V Cu²⁺(aq) + 2 e^- → Cu(s) E° = +0.337 V

Which of the following statements concerning voltaic cells is not true?

Which of the following is the cell notation for a cell in which the hydrogen electrode is the anode and the cathode half-reaction is Co³⁺(aq) + e− → Co²⁺(aq) ?

The standard reduction potentials are as follows: Cr³⁺(aq) + 3 e^- → Cr(s) ; E° = -0.74 V Fe²⁺(aq) + 2 e^- → Fe(s) ; E° = -0.41 V Calculate the standard Gibbs free energy change for the following reaction. 2 Cr(s) + 3 Fe²⁺ → 3 Fe(s) + 2 Cr³⁺(aq)

Balance the following half-reaction occurring in an acidic solution. NO₃^-(aq) → NO(aq)

The standard cell potential of the given electrochemical cell is 0.19 V. Pt | Sn⁴⁺(aq, 1.0 M) , Sn²⁺(aq, 1.0 M) || Cu²⁺(aq, 0.200 M) | Cu Which of the following factors will increase the measured cell potential of the given electrochemical cell?

According to the cell notation below, which of the following species is undergoing reduction? Ni | Ni²⁺(aq) || Mn²⁺(aq) | MnO₂(s) | Pt(s)

What half-reaction occurs at the cathode during the electrolysis of molten potassium bromide?

If ?_rG° for the following reaction is -22.2 kJ/mol-rxn, calculate $E _ { \text {cell } } ^ { \circ }$ for the following reaction: Cu²⁺(aq) + 2 Ag(s) + 2 Cl^-(aq) ? Cu(s) + 2 AgCl(s)

The use of electrical energy to produce chemical change is known as _____. An example of this process is the reduction of sodium chloride, NaCl( $\ell$ ), to produce solid sodium.

Which of the following statements is true for the following reaction, assuming the given reaction proceeds in the forward direction? Fe³⁺(aq) + Co(s) → Fe²⁺(aq) + Co²⁺(aq)

Which of the following equations represents the Nernst equation?

Exam 20: Principles of Chemical Reactivity: Electron Transfer Reactions

Which of the following statements is true concerning the electrochemical cell Zn(s) | Zn2+(aq, 1.0 M) || Ca2+(aq, 1.0 M) | Ca(s) The standard reduction potentials are given follows: Zn2+(aq) + 2 e− → Zn(s) ; E° = -0.76 V Ca2+(aq) + 2 e− → Ca(s) ; E° = -2.87 V

Which of the following statements is true concerning the voltaic cell shown below?

Which of the following is true for a product-favored reaction at equilibrium?

Write a balanced half-reaction for the reduction of hydrogen peroxide to water in an acidic solution.

Calculate ΔrG° for the disproportionation reaction of copper(I) ion (Cu+) at 25 °C. 2 Cu+(aq) → Cu2+(aq) + Cu(s) The standard reduction potentials are as follows: Cu+(aq) + e- → Cu(s) E° = +0.518 V Cu2+(aq) + 2 e- → Cu(s) E° = +0.337 V

Which of the following statements concerning voltaic cells is not true?

Which of the following is the cell notation for a cell in which the hydrogen electrode is the anode and the cathode half-reaction is Co3+(aq) + e− → Co2+(aq) ?

The standard reduction potentials are as follows: Cr3+(aq) + 3 e- → Cr(s) ; E° = -0.74 V Fe2+(aq) + 2 e- → Fe(s) ; E° = -0.41 V Calculate the standard Gibbs free energy change for the following reaction. 2 Cr(s) + 3 Fe2+ → 3 Fe(s) + 2 Cr3+(aq)

Balance the following half-reaction occurring in an acidic solution. NO3-(aq) → NO(aq)

The standard cell potential of the given electrochemical cell is 0.19 V. Pt | Sn4+(aq, 1.0 M) , Sn2+(aq, 1.0 M) || Cu2+(aq, 0.200 M) | Cu Which of the following factors will increase the measured cell potential of the given electrochemical cell?

According to the cell notation below, which of the following species is undergoing reduction? Ni | Ni2+(aq) || Mn2+(aq) | MnO2(s) | Pt(s)

What half-reaction occurs at the cathode during the electrolysis of molten potassium bromide?

If ?rG° for the following reaction is -22.2 kJ/mol-rxn, calculate Ecell ∘E _ { \text {cell } } ^ { \circ }Ecell ∘​ for the following reaction: Cu2+(aq) + 2 Ag(s) + 2 Cl-(aq) ? Cu(s) + 2 AgCl(s)

Calculate Ecell for the following electrochemical cell at 25 °C Pt(s) | H2(g, 1.00 atm) | H+(aq, 1.00 M) || Sn2+(aq, 0.350 M) , Sn4+(aq, 0.020 M) | Pt(s) The standard reduction potentials are as follows: Sn4+(aq) + 2 e- → Sn2+(s) E° = +0.15 V 2 H+(aq) + 2 e- → H2(g) E° = 0.00 V

The use of electrical energy to produce chemical change is known as _____. An example of this process is the reduction of sodium chloride, NaCl( ℓ\ellℓ ), to produce solid sodium.

Which of the following statements is true for the following reaction, assuming the given reaction proceeds in the forward direction? Fe3+(aq) + Co(s) → Fe2+(aq) + Co2+(aq)

Which of the following equations represents the Nernst equation?

Which of the following statements is true concerning the electrochemical cell Zn(s) | Zn²⁺(aq, 1.0 M) || Ca²⁺(aq, 1.0 M) | Ca(s) The standard reduction potentials are given follows: Zn²⁺(aq) + 2 e− → Zn(s) ; E° = -0.76 V Ca²⁺(aq) + 2 e− → Ca(s) ; E° = -2.87 V

Calculate Δ_rG° for the disproportionation reaction of copper(I) ion (Cu⁺) at 25 °C. 2 Cu⁺(aq) → Cu²⁺(aq) + Cu(s) The standard reduction potentials are as follows: Cu⁺(aq) + e^- → Cu(s) E° = +0.518 V Cu²⁺(aq) + 2 e^- → Cu(s) E° = +0.337 V

Which of the following is the cell notation for a cell in which the hydrogen electrode is the anode and the cathode half-reaction is Co³⁺(aq) + e− → Co²⁺(aq) ?

The standard reduction potentials are as follows: Cr³⁺(aq) + 3 e^- → Cr(s) ; E° = -0.74 V Fe²⁺(aq) + 2 e^- → Fe(s) ; E° = -0.41 V Calculate the standard Gibbs free energy change for the following reaction. 2 Cr(s) + 3 Fe²⁺ → 3 Fe(s) + 2 Cr³⁺(aq)

Balance the following half-reaction occurring in an acidic solution. NO₃^-(aq) → NO(aq)

The standard cell potential of the given electrochemical cell is 0.19 V. Pt | Sn⁴⁺(aq, 1.0 M) , Sn²⁺(aq, 1.0 M) || Cu²⁺(aq, 0.200 M) | Cu Which of the following factors will increase the measured cell potential of the given electrochemical cell?

According to the cell notation below, which of the following species is undergoing reduction? Ni | Ni²⁺(aq) || Mn²⁺(aq) | MnO₂(s) | Pt(s)

If ?_rG° for the following reaction is -22.2 kJ/mol-rxn, calculate $E _ { \text {cell } } ^ { \circ }$ for the following reaction: Cu²⁺(aq) + 2 Ag(s) + 2 Cl^-(aq) ? Cu(s) + 2 AgCl(s)

The use of electrical energy to produce chemical change is known as _____. An example of this process is the reduction of sodium chloride, NaCl( $\ell$ ), to produce solid sodium.

Which of the following statements is true for the following reaction, assuming the given reaction proceeds in the forward direction? Fe³⁺(aq) + Co(s) → Fe²⁺(aq) + Co²⁺(aq)