Question 1

Cathodic protection of a metal pipe against corrosion usually entails ________.

Accepted Answer

A) attaching an active metal to make the pipe the anode in an electrochemical cell 
B) coating the pipe with another metal whose standard reduction potential is less negative than that of the pipe 
C) attaching an active metal to make the pipe the cathode in an electrochemical cell 
D) attaching a dry cell to reduce any metal ions which might be formed 
E) coating the pipe with a fluoropolymer to act as a source of fluoride ion (since the latter is so hard to oxidize) 
A) attaching an active metal to make the pipe the anode in an electrochemical cell 
B) coating the pipe with another metal whose standard reduction potential is less negative than that of the pipe 
C) attaching an active metal to make the pipe the cathode in an electrochemical cell 
D) attaching a dry cell to reduce any metal ions which might be formed 
E) coating the pipe with a fluoropolymer to act as a source of fluoride ion (since the latter is so hard to oxidize)

Question 2

The standard cell potential (E°cell)of the reaction below is -0.55 V. The value of ΔG° for the reaction is ________ J/mol. I2 (s) + 2Br- (aq) → 2I- (aq) + Br2 (l)

Accepted Answer

A) 0.54 
B) 0.55 
C) 5.5 × 10-6 
D) 1.1 × 105 
E) none of the above 
A) 0.54 
B) 0.55 
C) 5.5 × 10-6 
D) 1.1 × 105 
E) none of the above

Question 3

How many seconds are required to produce 5.00 g of aluminum metal from the electrolysis of molten AlCl3 with an electrical current of 15.0 A?

Accepted Answer

A) 27.0 
B) 9.00 
C) 1.19E × 103  
D) 2.90 × 105 
E) 3.57 × 103 
A) 27.0 
B) 9.00 
C) 1.19E × 103  
D) 2.90 × 105 
E) 3.57 × 103

Question 4

The potential (E)to move K+ from the extracellular fluid to the intracellular fluid necessitates work. The sign for this potential is ________.

Accepted Answer

Question 5

The half-reaction occurring at the anode in the balanced reaction shown below is ________. 3MnO4- (aq) + 24H+ (aq) + 5Fe (s) → 3Mn2+ (aq) + 5Fe3+ (aq) + 12H2O (l)

Accepted Answer

A) MnO4- (aq) + 8H+ (aq) + 5e- → Mn2+ (aq) + 4H2O (l) 
B) 2MnO4- (aq) + 12H+ (aq) + 6e- → 2Mn2+ (aq) + 3H2O (l) 
C) Fe (s) → Fe3+ (aq) + 3e- 
D) Fe (s) → Fe2+ (aq) + 2e- 
E) Fe2+ (aq) → Fe3+ (aq) + e- 
A) MnO4- (aq) + 8H+ (aq) + 5e- → Mn2+ (aq) + 4H2O (l) 
B) 2MnO4- (aq) + 12H+ (aq) + 6e- → 2Mn2+ (aq) + 3H2O (l) 
C) Fe (s) → Fe3+ (aq) + 3e- 
D) Fe (s) → Fe2+ (aq) + 2e- 
E) Fe2+ (aq) → Fe3+ (aq) + e-

Question 6

________ is reduced in the following reaction: Cr2O72- + 6S2O32- + 14H+ → 2Cr3+ + 3S4O62 + 7H2O

Accepted Answer

A) Cr6+ 
B) S2+ 
C) H+ 
D) O2- 
E) S4O62- 
A) Cr6+ 
B) S2+ 
C) H+ 
D) O2- 
E) S4O62-

Question 7

The standard reduction potential of X is 1.23 V and that of Y is -0.44 V; therefore X is oxidized by Y.

Accepted Answer

A) True 
 B)False

Question 8

When iron is coated with a thin layer of zinc to protect against corrosion, the iron is said to be ________.

Accepted Answer

The answer of When iron is coated with a thin...

Question 9

The standard reduction potential, E°red, is proportional to the stoichiometric coefficient.

Accepted Answer

A) True 
 B)False

Question 10

A voltaic cell is constructed with two silver-silver chloride electrodes, where the half-reaction is AgCl (s) + e- → Ag (s) + Cl- (aq)E° = +0.222 V
The concentrations of chloride ion in the two compartments are 0.0100 M and 1.55 M, respectively. The cell emf is ________ V.

Accepted Answer

A) 0.216 
B) 0.130 
C) 0.00143 
D) 34.4 
E) 0.228 
A) 0.216 
B) 0.130 
C) 0.00143 
D) 34.4 
E) 0.228

Question 11

The balanced half-reaction in which sulfate ion is reduced to sulfite ion is a ________ process.

Accepted Answer

A) four-electron 
B) one-electron 
C) two-electron 
D) three-electron 
E) six-electron 
A) four-electron 
B) one-electron 
C) two-electron 
D) three-electron 
E) six-electron

Question 12

Table 20.2  
-Which of the following reactions will occur spontaneously as written?

Accepted Answer

A) 3Fe2+ (aq) + Cr3+ (aq) → Cr (s) + 3Fe3+ (aq) 
B) 2Cr3+ (aq) + 3Sn2+ (aq) → 3Sn4+ (aq) + 2Cr (s) 
C) Sn4+ (aq) + Fe2+ (s) → Sn2+ (aq) + Fe (s) 
D) Sn2+ (aq) + Fe2+ (s) → Sn4+ (aq) + Fe3+ (aq) 
E) 2Cr (s) + 3Fe2+ (s) → 3Fe (s) + 2Cr3+ (aq) 
A) 3Fe2+ (aq) + Cr3+ (aq) → Cr (s) + 3Fe3+ (aq) 
B) 2Cr3+ (aq) + 3Sn2+ (aq) → 3Sn4+ (aq) + 2Cr (s) 
C) Sn4+ (aq) + Fe2+ (s) → Sn2+ (aq) + Fe (s) 
D) Sn2+ (aq) + Fe2+ (s) → Sn4+ (aq) + Fe3+ (aq) 
E) 2Cr (s) + 3Fe2+ (s) → 3Fe (s) + 2Cr3+ (aq)

Question 13

The most useful ore of aluminum is bauxite, in which Al is present as hydrated oxides, Al2O3 · xH2O. The number of kilowatt-hours of electricity required to produce 3.00 kg of aluminum from electrolysis of compounds from bauxite is ________ when the applied emf is 4.50 V.

Accepted Answer

A) 0.0249 
B) 0.0402 
C) 26.8 
D) 13.4 
E) 40.2 
A) 0.0249 
B) 0.0402 
C) 26.8 
D) 13.4 
E) 40.2

Question 14

The standard emf for the cell using the overall cell reaction below is +0.48 V: Zn (s) + Ni2+ (aq) → Zn2+ (aq) + Ni (s)
The emf generated by the cell when [Ni2+] = 0.100 M and [Zn2+] = 2.25 M is

Accepted Answer

A) 0.56 
B) 0.50 
C) 0.44 
D) 0.40 
E) 0.52 
A) 0.56 
B) 0.50 
C) 0.44 
D) 0.40 
E) 0.52

Question 15

Table 20.2  
-The standard cell potential (E°cell)for the voltaic cell based on the reaction below is ________ V. Sn2+ (aq) + 2Fe3+ (aq) → 2Fe2+ (aq) + Sn4+ (aq)

Accepted Answer

A) +0.46 
B) +0.617 
C) +1.39 
D) -0.46 
E) +1.21 
A) +0.46 
B) +0.617 
C) +1.39 
D) -0.46 
E) +1.21

Question 16

Consider an electrochemical cell based on the reaction: 2H+ (aq) + Sn (s) → Sn2+ (aq) + H2 (g)
Which of the following actions would change the measured cell potential?

Accepted Answer

A) increasing the pH in the cathode compartment 
B) lowering the pH in the cathode compartment 
C) increasing the [Sn2+] in the anode compartment 
D) increasing the pressure of hydrogen gas in the cathode compartment 
E) Any of the above will change the measure cell potential. 
A) increasing the pH in the cathode compartment 
B) lowering the pH in the cathode compartment 
C) increasing the [Sn2+] in the anode compartment 
D) increasing the pressure of hydrogen gas in the cathode compartment 
E) Any of the above will change the measure cell potential.

Question 17

In a voltaic cell electrons flow from the anode to the cathode.

Accepted Answer

A) True 
 B)False

Question 18

What is the anode in an alkaline battery?

Accepted Answer

A) MnO2 
B) KOH 
C) Zn powder 
D) Mn2O3 
E) Pt 
A) MnO2 
B) KOH 
C) Zn powder 
D) Mn2O3 
E) Pt

Question 19

The town of Natrium, West Virginia, derives its name from the sodium produced in the electrolysis of molten sodium chloride (NaCl)mined from ancient salt deposits. The number of kilowatt-hours of electricity required to produce 4.50 kg of metallic sodium from the electrolysis of molten NaCl(s)is ________ when the applied emf is 5.00 V.

Accepted Answer

A) 26.2 
B) 0.0381 
C) 0.0262 
D) 52.5 
E) 13.1 
A) 26.2 
B) 0.0381 
C) 0.0262 
D) 52.5 
E) 13.1

Question 20

Corrosion of iron is retarded by ________.

Accepted Answer

A) the presence of salts 
B) high pH conditions 
C) low pH conditions 
D) both the presence of salts and high pH conditions 
E) both the presence of salts and low pH conditions 
A) the presence of salts 
B) high pH conditions 
C) low pH conditions 
D) both the presence of salts and high pH conditions 
E) both the presence of salts and low pH conditions

Exam 20: Electrochemistry

Cathodic protection of a metal pipe against corrosion usually entails ________.

The standard cell potential (E°cell)of the reaction below is -0.55 V. The value of ΔG° for the reaction is ________ J/mol. I2 (s) + 2Br- (aq) → 2I- (aq) + Br2 (l)

How many seconds are required to produce 5.00 g of aluminum metal from the electrolysis of molten AlCl3 with an electrical current of 15.0 A?

The potential (E)to move K+ from the extracellular fluid to the intracellular fluid necessitates work. The sign for this potential is ________.

The half-reaction occurring at the anode in the balanced reaction shown below is ________. 3MnO4- (aq) + 24H+ (aq) + 5Fe (s) → 3Mn2+ (aq) + 5Fe3+ (aq) + 12H2O (l)

________ is reduced in the following reaction: Cr2O72- + 6S2O32- + 14H+ → 2Cr3+ + 3S4O62 + 7H2O

The standard reduction potential of X is 1.23 V and that of Y is -0.44 V; therefore X is oxidized by Y.

When iron is coated with a thin layer of zinc to protect against corrosion, the iron is said to be ________.

The standard reduction potential, E°red, is proportional to the stoichiometric coefficient.

A voltaic cell is constructed with two silver-silver chloride electrodes, where the half-reaction is AgCl (s) + e- → Ag (s) + Cl- (aq)E° = +0.222 V The concentrations of chloride ion in the two compartments are 0.0100 M and 1.55 M, respectively. The cell emf is ________ V.

The balanced half-reaction in which sulfate ion is reduced to sulfite ion is a ________ process.

Table 20.2 -Which of the following reactions will occur spontaneously as written?

The most useful ore of aluminum is bauxite, in which Al is present as hydrated oxides, Al2O3 · xH2O. The number of kilowatt-hours of electricity required to produce 3.00 kg of aluminum from electrolysis of compounds from bauxite is ________ when the applied emf is 4.50 V.

The standard emf for the cell using the overall cell reaction below is +0.48 V: Zn (s) + Ni2+ (aq) → Zn2+ (aq) + Ni (s) The emf generated by the cell when [Ni2+] = 0.100 M and [Zn2+] = 2.25 M is

Table 20.2 -The standard cell potential (E°cell)for the voltaic cell based on the reaction below is ________ V. Sn2+ (aq) + 2Fe3+ (aq) → 2Fe2+ (aq) + Sn4+ (aq)

Consider an electrochemical cell based on the reaction: 2H+ (aq) + Sn (s) → Sn2+ (aq) + H2 (g) Which of the following actions would change the measured cell potential?

In a voltaic cell electrons flow from the anode to the cathode.

What is the anode in an alkaline battery?

Corrosion of iron is retarded by ________.

Introduction: Matter and Measurement

Atoms, Molecules, and Ions

Stoichiometry: Calculations With Chemical Formulas and Equations

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The standard cell potential (E°_cell)of the reaction below is -0.55 V. The value of ΔG° for the reaction is ________ J/mol. I₂ (s) + 2Br^- (aq) → 2I^- (aq) + Br₂ (l)

How many seconds are required to produce 5.00 g of aluminum metal from the electrolysis of molten AlCl₃ with an electrical current of 15.0 A?

The potential (E)to move K⁺ from the extracellular fluid to the intracellular fluid necessitates work. The sign for this potential is ________.

The half-reaction occurring at the anode in the balanced reaction shown below is ________. 3MnO₄^- (aq) + 24H⁺ (aq) + 5Fe (s) → 3Mn²⁺ (aq) + 5Fe³⁺ (aq) + 12H₂O (l)

________ is reduced in the following reaction: Cr₂O₇^2- + 6S₂O₃^2- + 14H⁺ → 2Cr³⁺ + 3S₄O₆² + 7H₂O

The standard reduction potential, E°_red, is proportional to the stoichiometric coefficient.

A voltaic cell is constructed with two silver-silver chloride electrodes, where the half-reaction is AgCl (s) + e^- → Ag (s) + Cl^- (aq)E° = +0.222 V The concentrations of chloride ion in the two compartments are 0.0100 M and 1.55 M, respectively. The cell emf is ________ V.

The most useful ore of aluminum is bauxite, in which Al is present as hydrated oxides, Al₂O₃ · xH₂O. The number of kilowatt-hours of electricity required to produce 3.00 kg of aluminum from electrolysis of compounds from bauxite is ________ when the applied emf is 4.50 V.

The standard emf for the cell using the overall cell reaction below is +0.48 V: Zn (s) + Ni²⁺ (aq) → Zn²⁺ (aq) + Ni (s) The emf generated by the cell when [Ni²⁺] = 0.100 M and [Zn²⁺] = 2.25 M is

Table 20.2 -The standard cell potential (E°_cell)for the voltaic cell based on the reaction below is ________ V. Sn²⁺ (aq) + 2Fe³⁺ (aq) → 2Fe²⁺ (aq) + Sn⁴⁺ (aq)

Consider an electrochemical cell based on the reaction: 2H⁺ (aq) + Sn (s) → Sn²⁺ (aq) + H₂ (g) Which of the following actions would change the measured cell potential?