Question 1

What is the reaction at the anode in a breathalyzer?

Accepted Answer

A) Ethanol is oxidized to acetic acid. 
B) Acetic acid is reduced to ethanol. 
C) Oxygen is reduced. 
D) Hydrogen is oxidized. 
E) Ethanol is oxidized to acetaldehyde. 
A) Ethanol is oxidized to acetic acid. 
B) Acetic acid is reduced to ethanol. 
C) Oxygen is reduced. 
D) Hydrogen is oxidized. 
E) Ethanol is oxidized to acetaldehyde.

Question 2

What is undergoing oxidation in the redox reaction represented by the following cell notation? 
$\quad$$\quad$$\quad$Pb(s)| Pb2+(aq) $\|$ H+(aq)| H2(g)| Pt(s)

Accepted Answer

A) H2(g) 
B) H+(aq) 
C) Pb2+(aq) 
D) Pb(s) 
E) Pt(s) 
A) H2(g) 
B) H+(aq) 
C) Pb2+(aq) 
D) Pb(s) 
E) Pt(s)

Question 3

For a galvanic cell that uses the following two half-reactions, 
$\quad$$\quad$Cr2O72-(aq)+ 14H+(aq)+ 6 e- → 2Cr3+(aq)+ 7H2O(l)
$\quad$$\quad$Pb(s)→ Pb2+(aq)+ 2 e-
How many moles of Pb(s)are oxidized by three moles of Cr2O72-?

Accepted Answer

A) 3 
B) 6 
C) 9 
D) 18 
A) 3 
B) 6 
C) 9 
D) 18

Question 4

Using the following standard reduction potentials, 
$\quad$$\quad$Fe3+(aq)+ e- →Fe2+(aq)E° = +0.77 V
$\quad$$\quad$Ni2+(aq)+ 2 e- →Ni(s)E° = -0.23 V
Calculate the standard cell potential for the galvanic cell reaction given below and determine whether or not this reaction is spontaneous under standard conditions.
$\quad$$\quad$Ni2+(aq)+ 2Fe2+(aq)→ 2Fe3+(aq)+ Ni(s)

Accepted Answer

A) E° = -1.00 V,nonspontaneous 
B) E° = -1.00 V,spontaneous 
C) E° = +1.00 V,nonspontaneous 
D) E° = +1.00 V,spontaneous 
A) E° = -1.00 V,nonspontaneous 
B) E° = -1.00 V,spontaneous 
C) E° = +1.00 V,nonspontaneous 
D) E° = +1.00 V,spontaneous

Question 5

What is the reducing agent in the redox reaction represented by the following cell notation? 
$\quad$$\quad$$\quad$Sn(s)| Sn2+(aq) $\|$ Ag+(aq)| Ag(s)

Accepted Answer

A) Sn(s) 
B) Ag+(aq) 
C) Sn2+(aq) 
D) Ag(s) 
E) Pt(s) 
A) Sn(s) 
B) Ag+(aq) 
C) Sn2+(aq) 
D) Ag(s) 
E) Pt(s)

Question 6

How much copper,in g,can be plated from a solution of $\mathrm { Cu } ^ { 2 + }$ if 3.14 A is applied for 45 minutes?

Accepted Answer

A) 2.79 g 
B) 1.85 g 
C) 11.2 g 
D) 0.283 g 
E) 7.64 g 
A) 2.79 g 
B) 1.85 g 
C) 11.2 g 
D) 0.283 g 
E) 7.64 g

Question 7

Predict the species that will be reduced first if a mixture of molten salts containing the following ions undergoes electrolysis: 
$\quad$$\quad$Zn2+,Fe3+,Mg2+,Br-,I-

Accepted Answer

A) Zn2+ 
B) Mg2+ 
C) Br- 
D) Fe3+ 
E) I- 
A) Zn2+ 
B) Mg2+ 
C) Br- 
D) Fe3+ 
E) I-

Question 8

Predict the species that will be reduced first if a mixture of molten salts containing the following ions undergoes electrolysis: 
$\quad$$\quad$Na+,Ca2+,Cl-,Br-,F-

Accepted Answer

A) Na+ 
B) Cl- 
C) Ca2+ 
D) Br- 
E) F- 
A) Na+ 
B) Cl- 
C) Ca2+ 
D) Br- 
E) F-

Question 9

Explain the significance of the standard hydrogen electrode (SHE)in the tabulation of standard reduction potentials of other species.

Accepted Answer

The SHE is used to construct an electroc

Question 10

Use the provided reduction potentials to calculate ΔrG° for the following balanced redox reaction: 
$\quad$$\quad$3I2(s)+ 2Fe(s)→ 2Fe3+(aq)+ 6I- (aq)
E°(I2/I-)= + 0.54 V and E°(Fe3+/Fe)= -0.036 V

Accepted Answer

A) -1.1 × 102 kJ mol-1 
B) +4.9 × 101 kJ mol-1 
C) -9.7 × 101 kJ mol-1 
D) +2.3 × 102 kJ mol-1 
E) -3.3 × 102 kJ mol-1 
A) -1.1 × 102 kJ mol-1 
B) +4.9 × 101 kJ mol-1 
C) -9.7 × 101 kJ mol-1 
D) +2.3 × 102 kJ mol-1 
E) -3.3 × 102 kJ mol-1

Question 11

How much chromium,in g,can be plated from a solution of $\mathrm { Cr } ^ { 3 }$ if 2.72 A is applied for 15 minutes?

Accepted Answer

A) 1.32 g 
B) 6.51 × $10 ^ { - 3 }$ g 
C) 0.937 g 
D) 0.440 g 
E) 4.67 g 
A) 1.32 g 
B) 6.51 × $10 ^ { - 3 }$ g 
C) 0.937 g 
D) 0.440 g 
E) 4.67 g

Question 12

How many grams of nickel metal are plated out when a constant current of 15.0 A is passed through aqueous NiCl2 for 60.0 minutes?

Accepted Answer

A) 10.9 g 
B) 16.4 g 
C) 32.8 g 
D) 36.3 g 
A) 10.9 g 
B) 16.4 g 
C) 32.8 g 
D) 36.3 g

Question 13

What is the shorthand notation that represents the following galvanic cell reaction? 
$\quad$$\quad$Pb(s)+ Cu(NO3)2(aq)→ Pb(NO3)2(aq)+ Cu(s)

Accepted Answer

A) Pb(s)| Pb2+(aq)|| Cu2+(aq)| Cu(s) 
B) Cu(s)| Cu2+(aq)|| Pb2+(aq)| Pb(s) 
C) Pb(s)| NO3-(aq)|| NO3-(aq)| Cu(s) 
D) Cu(s)| Cu(NO3)2(aq)|| Pb(NO3)2(aq)| Pb(s) 
A) Pb(s)| Pb2+(aq)|| Cu2+(aq)| Cu(s) 
B) Cu(s)| Cu2+(aq)|| Pb2+(aq)| Pb(s) 
C) Pb(s)| NO3-(aq)|| NO3-(aq)| Cu(s) 
D) Cu(s)| Cu(NO3)2(aq)|| Pb(NO3)2(aq)| Pb(s)

Question 14

Use the tabulated half-cell potentials to calculate the equilibrium constant (K)for the following balanced redox reaction at 25 °C: 
$\quad$$\quad$Pb2+(aq)+ Cu(s)→ Pb(s)+ Cu2+(aq)
E°(Pb2+/Pb)= -0.13 V and E°(Cu2+/Cu)= +0.34 V

Accepted Answer

A) 7.9 × 10-8 
B) 8.9 × 107 
C) 7.9 × 1015 
D) 1.3 × 10-16 
E) 1.1 × 10-8 
A) 7.9 × 10-8 
B) 8.9 × 107 
C) 7.9 × 1015 
D) 1.3 × 10-16 
E) 1.1 × 10-8

Question 15

Which of the following metals will dissolve in nitric acid but not hydrochloric acid?

Accepted Answer

A) Fe; E°(Fe2+/Fe)= -0.45V 
B) Pb; E°(Pb2+/Pb)= -0.13V 
C) Cu; E°(Cu2+/Cu)= +0.34V 
D) Sn; E°(Sn2+/Sn)= -0.14V 
E) Ni; E°(Ni2+/Ni)= -0.23V 
A) Fe; E°(Fe2+/Fe)= -0.45V 
B) Pb; E°(Pb2+/Pb)= -0.13V 
C) Cu; E°(Cu2+/Cu)= +0.34V 
D) Sn; E°(Sn2+/Sn)= -0.14V 
E) Ni; E°(Ni2+/Ni)= -0.23V

Question 16

Calculate the cell potential for the following unbalanced reaction that takes place in an electrochemical cell at 25 °C when [ $\mathrm { Mg } ^ { 2 + }$ ] = 0.000612 M and [ $\mathrm { Fe } ^ { 3 + }$ ] = 1.29 M 
$\quad$$\quad$Mg(s)+ $\mathrm { Fe } ^ { 3 + }$ (aq)? $\mathrm { Mg } ^ { 2 + }$ (aq)+ Fe(s)
E°(Mg2+/Mg)= -2.37 V and E°(Fe3+/Fe)= -0.036 V

Accepted Answer

A) -3.42 V 
B) +3.42 V 
C) -4.32 V 
D) +2.43 V 
E) +3.24 V 
A) -3.42 V 
B) +3.42 V 
C) -4.32 V 
D) +2.43 V 
E) +3.24 V

Question 17

In the presence of which of the following would iron be under the highest risk of rusting?

Accepted Answer

A) salt only 
B) moisture only 
C) acid only 
D) salt and moisture combined 
E) salt,moisture,and acid together 
A) salt only 
B) moisture only 
C) acid only 
D) salt and moisture combined 
E) salt,moisture,and acid together

Question 18

Use the provided reduction potentials to calculate ΔrG° for the following redox reaction: 
$\quad$$\quad$2Al(s)+ 3Mg2+(aq)→ 2Al3+(aq)+ 3Mg(s)
E°(Al3+/Al)= -1.66 V and E°(Mg2+/Mg)= -2.37 V

Accepted Answer

A) +4.1 × 102 kJ mol-1 
B) +1.4 × 102 kJ mol-1 
C) -2.3 × 102 kJ mol-1 
D) -7.8 × 102 kJ mol-1 
E) +6.8 × 102 kJ mol-1 
A) +4.1 × 102 kJ mol-1 
B) +1.4 × 102 kJ mol-1 
C) -2.3 × 102 kJ mol-1 
D) -7.8 × 102 kJ mol-1 
E) +6.8 × 102 kJ mol-1

Question 19

Determine the cell notation for the redox reaction given below: 
$\quad$$\quad$Pb(s)+ 2H+ (aq)? Pb2+(aq)+ H2(g)

Accepted Answer

A) H+(aq)| H2(g)| Pt(s) $\|$ Pb(s)| Pb2+(aq) 
B) H2(g)| H+(aq)| Pt(s) $\|$ Pb2+(aq)| Pb(s) 
C) Pb2+(aq)| Pb(s) $\|$ H2(g)| H+(aq)| Pt(s) 
D) Pb(s)| Pb2+(aq) $\|$ H+(aq)| H2(g)| Pt(s) 
E) Pb(s)| H2(g) $\|$ Pb2+(aq)| H+(aq)| Pt(s) 
A) H+(aq)| H2(g)| Pt(s) $\|$ Pb(s)| Pb2+(aq) 
B) H2(g)| H+(aq)| Pt(s) $\|$ Pb2+(aq)| Pb(s) 
C) Pb2+(aq)| Pb(s) $\|$ H2(g)| H+(aq)| Pt(s) 
D) Pb(s)| Pb2+(aq) $\|$ H+(aq)| H2(g)| Pt(s) 
E) Pb(s)| H2(g) $\|$ Pb2+(aq)| H+(aq)| Pt(s)

Question 20

Calculate the cell potential for the following reaction that takes place in an electrochemical cell at 25 °C: 
$\quad$$\quad$$\quad$Sn(s)| Sn2+(aq,0.100 mol L-1) $\|$ Ag+(aq,0.200 mol L-1)| Ag(s)
E°(Sn2+/Sn)= -0.14 V and E°(Ag+/Ag)= +0.80 V

Accepted Answer

A) -2.68 V 
B) -0.03 V 
C) +0.95 V 
D) +0.93 V 
E) +2.10 V 
A) -2.68 V 
B) -0.03 V 
C) +0.95 V 
D) +0.93 V 
E) +2.10 V

Exam 18: Electrochemistry

What is the reaction at the anode in a breathalyzer?

What is undergoing oxidation in the redox reaction represented by the following cell notation? \quad\quad\quad Pb(s)| Pb2+(aq) ∥\|∥ H+(aq)| H2(g)| Pt(s)

For a galvanic cell that uses the following two half-reactions, \quad\quad Cr2O72-(aq)+ 14H+(aq)+ 6 e- → 2Cr3+(aq)+ 7H2O(l) \quad\quad Pb(s)→ Pb2+(aq)+ 2 e- How many moles of Pb(s)are oxidized by three moles of Cr2O72-?

What is the reducing agent in the redox reaction represented by the following cell notation? \quad\quad\quad Sn(s)| Sn2+(aq) ∥\|∥ Ag+(aq)| Ag(s)

How much copper,in g,can be plated from a solution of Cu2+\mathrm { Cu } ^ { 2 + }Cu2+ if 3.14 A is applied for 45 minutes?

Predict the species that will be reduced first if a mixture of molten salts containing the following ions undergoes electrolysis: \quad\quad Zn2+,Fe3+,Mg2+,Br-,I-

Predict the species that will be reduced first if a mixture of molten salts containing the following ions undergoes electrolysis: \quad\quad Na+,Ca2+,Cl-,Br-,F-

Explain the significance of the standard hydrogen electrode (SHE)in the tabulation of standard reduction potentials of other species.

Use the provided reduction potentials to calculate ΔrG° for the following balanced redox reaction: \quad\quad 3I2(s)+ 2Fe(s)→ 2Fe3+(aq)+ 6I- (aq) E°(I2/I-)= + 0.54 V and E°(Fe3+/Fe)= -0.036 V

How much chromium,in g,can be plated from a solution of Cr3\mathrm { Cr } ^ { 3 }Cr3 if 2.72 A is applied for 15 minutes?

How many grams of nickel metal are plated out when a constant current of 15.0 A is passed through aqueous NiCl2 for 60.0 minutes?

What is the shorthand notation that represents the following galvanic cell reaction? \quad\quad Pb(s)+ Cu(NO3)2(aq)→ Pb(NO3)2(aq)+ Cu(s)

Use the tabulated half-cell potentials to calculate the equilibrium constant (K)for the following balanced redox reaction at 25 °C: \quad\quad Pb2+(aq)+ Cu(s)→ Pb(s)+ Cu2+(aq) E°(Pb2+/Pb)= -0.13 V and E°(Cu2+/Cu)= +0.34 V

Which of the following metals will dissolve in nitric acid but not hydrochloric acid?

In the presence of which of the following would iron be under the highest risk of rusting?

Use the provided reduction potentials to calculate ΔrG° for the following redox reaction: \quad\quad 2Al(s)+ 3Mg2+(aq)→ 2Al3+(aq)+ 3Mg(s) E°(Al3+/Al)= -1.66 V and E°(Mg2+/Mg)= -2.37 V

Determine the cell notation for the redox reaction given below: \quad\quad Pb(s)+ 2H+ (aq)? Pb2+(aq)+ H2(g)

Calculate the cell potential for the following reaction that takes place in an electrochemical cell at 25 °C: \quad\quad\quad Sn(s)| Sn2+(aq,0.100 mol L-1) ∥\|∥ Ag+(aq,0.200 mol L-1)| Ag(s) E°(Sn2+/Sn)= -0.14 V and E°(Ag+/Ag)= +0.80 V

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Chemical Reactions and Stoichiometry

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Filters

What is undergoing oxidation in the redox reaction represented by the following cell notation? $\quad$ $\quad$ $\quad$ Pb(s)| Pb²⁺(aq) $\|$ H⁺(aq)| H₂(g)| Pt(s)

For a galvanic cell that uses the following two half-reactions, $\quad$ $\quad$ Cr₂O₇^2-(aq)+ 14H⁺(aq)+ 6 e^- → 2Cr³⁺(aq)+ 7H₂O(l) $\quad$ $\quad$ Pb(s)→ Pb²⁺(aq)+ 2 e^- How many moles of Pb(s)are oxidized by three moles of Cr₂O₇^2-?

What is the reducing agent in the redox reaction represented by the following cell notation? $\quad$ $\quad$ $\quad$ Sn(s)| Sn²⁺(aq) $\|$ Ag⁺(aq)| Ag(s)

How much copper,in g,can be plated from a solution of $\mathrm { Cu } ^ { 2 + }$ if 3.14 A is applied for 45 minutes?

Predict the species that will be reduced first if a mixture of molten salts containing the following ions undergoes electrolysis: $\quad$ $\quad$ Zn²⁺,Fe³⁺,Mg²⁺,Br^-,I^-

Predict the species that will be reduced first if a mixture of molten salts containing the following ions undergoes electrolysis: $\quad$ $\quad$ Na⁺,Ca²⁺,Cl^-,Br^-,F^-

Use the provided reduction potentials to calculate Δ_rG° for the following balanced redox reaction: $\quad$ $\quad$ 3I₂(s)+ 2Fe(s)→ 2Fe³⁺(aq)+ 6I^- (aq) E°(I₂/I^-)= + 0.54 V and E°(Fe³⁺/Fe)= -0.036 V

How much chromium,in g,can be plated from a solution of $\mathrm { Cr } ^ { 3 }$ if 2.72 A is applied for 15 minutes?

How many grams of nickel metal are plated out when a constant current of 15.0 A is passed through aqueous NiCl₂ for 60.0 minutes?

What is the shorthand notation that represents the following galvanic cell reaction? $\quad$ $\quad$ Pb(s)+ Cu(NO₃)₂(aq)→ Pb(NO₃)₂(aq)+ Cu(s)

Use the tabulated half-cell potentials to calculate the equilibrium constant (K)for the following balanced redox reaction at 25 °C: $\quad$ $\quad$ Pb²⁺(aq)+ Cu(s)→ Pb(s)+ Cu²⁺(aq) E°(Pb²⁺/Pb)= -0.13 V and E°(Cu²⁺/Cu)= +0.34 V

Use the provided reduction potentials to calculate Δ_rG° for the following redox reaction: $\quad$ $\quad$ 2Al(s)+ 3Mg²⁺(aq)→ 2Al³⁺(aq)+ 3Mg(s) E°(Al³⁺/Al)= -1.66 V and E°(Mg²⁺/Mg)= -2.37 V

Determine the cell notation for the redox reaction given below: $\quad$ $\quad$ Pb(s)+ 2H⁺ (aq)? Pb²⁺(aq)+ H₂(g)

Calculate the cell potential for the following reaction that takes place in an electrochemical cell at 25 °C: $\quad$ $\quad$ $\quad$ Sn(s)| Sn²⁺(aq,0.100 mol L^-1) $\|$ Ag⁺(aq,0.200 mol L^-1)| Ag(s) E°(Sn²⁺/Sn)= -0.14 V and E°(Ag⁺/Ag)= +0.80 V