Question 1

What is the standard free-energy change for the following reaction at 25°C? (F = 96,500 C • mol-1) 2Al(s) + 3Sn4+(aq,1 M) → 2Al3+(aq,1 M) + 3Sn2+(aq,1 M)

Accepted Answer

A)  -1.79 kJ/mol 
B)  1.79 kJ/mol 
C)  -1.04 × 103 kJ/mol 
D)  -3.45 × 102 kJ/mol 
E)  5.18 × 102 kJ/mol 
A)  -1.79 kJ/mol 
B)  1.79 kJ/mol 
C)  -1.04 × 103 kJ/mol 
D)  -3.45 × 102 kJ/mol 
E)  5.18 × 102 kJ/mol C

Question 2

If a substance is reduced, it must undergo a

Accepted Answer

A)  gain of electrons. 
B)  loss of oxygen. 
C)  gain of hydrogen. 
D)  loss of electrons. 
E)  gain of oxygen. 
A)  gain of electrons. 
B)  loss of oxygen. 
C)  gain of hydrogen. 
D)  loss of electrons. 
E)  gain of oxygen. A

Question 3

Which element is associated with the term "galvanized"?

Accepted Answer

A)  Ga 
B)  Zn 
C)  Cd 
D)  Hg 
E)  Pb 
A)  Ga 
B)  Zn 
C)  Cd 
D)  Hg 
E)  Pb B

Question 4

What is E°cell for a galvanic cell represented by the combination of the following half-reactions?

Accepted Answer

A)  -0.18 V 
B)  0.18 V 
C)  1.28 V 
D)  1.66 V 
E)  2.12 V 
A)  -0.18 V 
B)  0.18 V 
C)  1.28 V 
D)  1.66 V 
E)  2.12 V

Question 5

What would you observe if you set up the following electrochemical cell: Ag|AgNO3(0.001 M)||AgNO3(1 M)|Ag?

Accepted Answer

A)  Electrons will flow from left to right, causing a decrease in the AgNO3 concentration in the left cell, and an increase in the AgNO3 concentration in the right cell. 
B)  Electrons will flow from right to left, causing an increase in the AgNO3 concentration in the left cell, and a decrease in the AgNO3 concentration in the right cell. 
C)  Electrons will flow from left to right, causing an increase in the AgNO3 concentration in the left cell, and a decrease in AgNO3 concentration in the right cell. 
D)  Electrons will flow from right to left, causing a decrease in the AgNO3 concentration in the left cell, and an increase in the AgNO3 concentration in the right cell. 
E)  There will be no electron flow because the reduction potential at both electrodes is the same. 
A)  Electrons will flow from left to right, causing a decrease in the AgNO3 concentration in the left cell, and an increase in the AgNO3 concentration in the right cell. 
B)  Electrons will flow from right to left, causing an increase in the AgNO3 concentration in the left cell, and a decrease in the AgNO3 concentration in the right cell. 
C)  Electrons will flow from left to right, causing an increase in the AgNO3 concentration in the left cell, and a decrease in AgNO3 concentration in the right cell. 
D)  Electrons will flow from right to left, causing a decrease in the AgNO3 concentration in the left cell, and an increase in the AgNO3 concentration in the right cell. 
E)  There will be no electron flow because the reduction potential at both electrodes is the same.

Question 6

In the electrolyte of an electrochemical cell, current is carried by electrons moving from the anode to the cathode.

Accepted Answer

A) True 
 B)False

Question 7

Consider the reaction in the lead-acid cell Pb(s) + PbO2(s) + 2H2SO4(aq) → 2PbSO4(aq) + 2H2O(l)
For which E°cell = 2.04 V at 298 K. ΔG° for this reaction is

Accepted Answer

A)  -3.94 × 105 kJ/mol. 
B)  -3.94 × 102 kJ/mol. 
C)  -1.97 × 105 kJ/mol. 
D)  -7.87 × 102 kJ/mol. 
E)  -7.87 × 105 kJ/mol. 
A)  -3.94 × 105 kJ/mol. 
B)  -3.94 × 102 kJ/mol. 
C)  -1.97 × 105 kJ/mol. 
D)  -7.87 × 102 kJ/mol. 
E)  -7.87 × 105 kJ/mol.

Question 8

The redox reaction of peroxydisulfate with iodide has been used for many years as part of the iodine clock reaction. If E°cell= 1.587 V and E° of the cathode half-cell is 0.536 V, what is E° of the anode half-cell? S2O82-(aq) + 2H+ + 2I -(aq) → 2HSO4-(aq) + I2(aq)

Accepted Answer

A)  -1.051 V 
B)  -2.123 V 
C)  1.051 V 
D)  2.123 V 
E)  None of these choices is correct. 
A)  -1.051 V 
B)  -2.123 V 
C)  1.051 V 
D)  2.123 V 
E)  None of these choices is correct.

Question 9

A salt bridge allows movement of cations and anions from one half-cell to the other.

Accepted Answer

A) True 
 B)False

Question 10

What is the minimum voltage required for the electrolysis of 1.0 M NaCl in neutral solution? 2H2O + 2Cl- (1.0 M) → H2(1 atm) + Cl2(1 atm) + 2OH-(1 × 10-7 M)

Accepted Answer

A)  2.19 V 
B)  1.77 V 
C)  0.41 V 
D)  -0.41 V 
E)  -1.78 V 
A)  2.19 V 
B)  1.77 V 
C)  0.41 V 
D)  -0.41 V 
E)  -1.78 V

Question 11

The Faraday constant represents the charge of 1 mole of electrons.

Accepted Answer

A) True 
 B)False

Question 12

What product forms at the anode during the electrolysis of molten NaBr?

Accepted Answer

A)  Na+(l) 
B)  Na(l) 
C)  Br-(l) 
D)  Br3-(l) 
E)  Br2(g) 
A)  Na+(l) 
B)  Na(l) 
C)  Br-(l) 
D)  Br3-(l) 
E)  Br2(g)

Question 13

A cell can be prepared from copper and tin. What is the E°cell for the galvanic cell that forms from the following half-reactions?

Accepted Answer

A)  0.47 V 
B)  0.21 V 
C)  -0.21 V 
D)  -0.47 V 
E)  0.42 V 
A)  0.47 V 
B)  0.21 V 
C)  -0.21 V 
D)  -0.47 V 
E)  0.42 V

Question 14

Which is not a redox reaction?

Accepted Answer

A)  Al(OH)4-(aq) + 4H+(aq) → Al3+(aq) + 4H2O(l) 
B)  C6H12O6(s) + 6O2(g) → 6CO2(g) + 6H2O(l) 
C)  Na6FeCl8(s) + 2Na(l) → 8NaCl(s) + Fe(s) 
D)  2H2O2(aq) → 2H2O(l) + O2(g) 
E)  CO2(g) + H2(g) → CO(g) + H2O(g) 
A)  Al(OH)4-(aq) + 4H+(aq) → Al3+(aq) + 4H2O(l) 
B)  C6H12O6(s) + 6O2(g) → 6CO2(g) + 6H2O(l) 
C)  Na6FeCl8(s) + 2Na(l) → 8NaCl(s) + Fe(s) 
D)  2H2O2(aq) → 2H2O(l) + O2(g) 
E)  CO2(g) + H2(g) → CO(g) + H2O(g)

Question 15

Complete and balance the following redox equation using the set of smallest whole numbers coefficients. What is the sum of the coefficients? HI + HNO3 → I2 + NO (acidic solution)

Accepted Answer

A)  5 
B)  7 
C)  14 
D)  17 
E)  None of these choices is correct. 
A)  5 
B)  7 
C)  14 
D)  17 
E)  None of these choices is correct.

Question 16

What is ΔG° for the following reaction? (F = 96,500 C • mol -1) I2(s) + 2Br-(aq) → 2I-(aq) + Br2(l)
Given:

Accepted Answer

A)  +104 kJ/mol 
B)  -104 kJ/mol 
C)  +309 kJ/mol 
D)  +52 kJ/mol 
E)  -52 kJ/mol 
A)  +104 kJ/mol 
B)  -104 kJ/mol 
C)  +309 kJ/mol 
D)  +52 kJ/mol 
E)  -52 kJ/mol

Question 17

A metal object is to be gold-plated by an electrolytic procedure using aqueous AuCl3 electrolyte. How much gold may be deposited in 3.0 min by a constant current of 10. A?

Accepted Answer

A)  6.2 × 10-3 mol 
B)  9.3 × 10-3 mol 
C)  1.8 × 10-2 mol 
D)  3.5 × 10-5 mol 
E)  1.6 × 102 mol 
A)  6.2 × 10-3 mol 
B)  9.3 × 10-3 mol 
C)  1.8 × 10-2 mol 
D)  3.5 × 10-5 mol 
E)  1.6 × 102 mol

Question 18

How much charge must pass through an electrolytic cell to reduce 0.44 mol Ca2+ ion to calcium metal?

Accepted Answer

A)  1.9 ×105 C 
B)  8.5 ×104 C 
C)  2.1 ×104 C 
D)  4.3 ×104 C 
E)  0.88 C 
A)  1.9 ×105 C 
B)  8.5 ×104 C 
C)  2.1 ×104 C 
D)  4.3 ×104 C 
E)  0.88 C

Question 19

At equilibrium E° = 0.

Accepted Answer

A) True 
 B)False

Question 20

What is the equilibrium constant at 25°C for the following reaction? (R = 8.314 J/K • mol, F = 96,500 C • mol-1)

Accepted Answer

A)  4.1 × 1020 
B)  8.2 × 1030 
C)  3.3 × 1051 
D)  6.7 × 1061 
E)  > 9.9 × 1099 
A)  4.1 × 1020 
B)  8.2 × 1030 
C)  3.3 × 1051 
D)  6.7 × 1061 
E)  > 9.9 × 1099

Exam 19: Electrochemistry

What is the standard free-energy change for the following reaction at 25°C? (F = 96,500 C • mol-1) 2Al(s) + 3Sn4+(aq,1 M) → 2Al3+(aq,1 M) + 3Sn2+(aq,1 M)

If a substance is reduced, it must undergo a

Which element is associated with the term "galvanized"?

What is E°cell for a galvanic cell represented by the combination of the following half-reactions?

What would you observe if you set up the following electrochemical cell: Ag|AgNO3(0.001 M)||AgNO3(1 M)|Ag?

In the electrolyte of an electrochemical cell, current is carried by electrons moving from the anode to the cathode.

Consider the reaction in the lead-acid cell Pb(s) + PbO2(s) + 2H2SO4(aq) → 2PbSO4(aq) + 2H2O(l) For which E°cell = 2.04 V at 298 K. ΔG° for this reaction is

The redox reaction of peroxydisulfate with iodide has been used for many years as part of the iodine clock reaction. If E°cell= 1.587 V and E° of the cathode half-cell is 0.536 V, what is E° of the anode half-cell? S2O82-(aq) + 2H+ + 2I -(aq) → 2HSO4-(aq) + I2(aq)

A salt bridge allows movement of cations and anions from one half-cell to the other.

What is the minimum voltage required for the electrolysis of 1.0 M NaCl in neutral solution? 2H2O + 2Cl- (1.0 M) → H2(1 atm) + Cl2(1 atm) + 2OH-(1 × 10-7 M)

The Faraday constant represents the charge of 1 mole of electrons.

What product forms at the anode during the electrolysis of molten NaBr?

A cell can be prepared from copper and tin. What is the E°cell for the galvanic cell that forms from the following half-reactions?

Which is not a redox reaction?

Complete and balance the following redox equation using the set of smallest whole numbers coefficients. What is the sum of the coefficients? HI + HNO3 → I2 + NO (acidic solution)

What is ΔG° for the following reaction? (F = 96,500 C • mol -1) I2(s) + 2Br-(aq) → 2I-(aq) + Br2(l) Given:

A metal object is to be gold-plated by an electrolytic procedure using aqueous AuCl3 electrolyte. How much gold may be deposited in 3.0 min by a constant current of 10. A?

How much charge must pass through an electrolytic cell to reduce 0.44 mol Ca2+ ion to calcium metal?

At equilibrium E° = 0.

What is the equilibrium constant at 25°C for the following reaction? (R = 8.314 J/K • mol, F = 96,500 C • mol-1)

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What is the standard free-energy change for the following reaction at 25°C? (F = 96,500 C • mol^-1) 2Al(s) + 3Sn⁴⁺(aq,1 M) → 2Al³⁺(aq,1 M) + 3Sn²⁺(aq,1 M)

What is E°_cell for a galvanic cell represented by the combination of the following half-reactions?

What would you observe if you set up the following electrochemical cell: Ag|AgNO₃(0.001 M)||AgNO₃(1 M)|Ag?

Consider the reaction in the lead-acid cell Pb(s) + PbO₂(s) + 2H₂SO₄(aq) → 2PbSO₄(aq) + 2H₂O(l) For which E°_cell = 2.04 V at 298 K. ΔG° for this reaction is

The redox reaction of peroxydisulfate with iodide has been used for many years as part of the iodine clock reaction. If E°_cell= 1.587 V and E° of the cathode half-cell is 0.536 V, what is E° of the anode half-cell? S₂O₈^2-(aq) + 2H⁺+ 2I^-(aq) → 2HSO₄^-(aq) + I₂(aq)

What is the minimum voltage required for the electrolysis of 1.0 M NaCl in neutral solution? 2H₂O + 2Cl^-(1.0 M) → H₂(1 atm) + Cl₂(1 atm) + 2OH^-(1 × 10^-7^M)

A cell can be prepared from copper and tin. What is the E°_cell for the galvanic cell that forms from the following half-reactions?

Complete and balance the following redox equation using the set of smallest whole numbers coefficients. What is the sum of the coefficients? HI + HNO₃ → I₂ + NO (acidic solution)

What is ΔG° for the following reaction? (F = 96,500 C • mol^-1) I₂(s) + 2Br^-(aq) → 2I^-(aq) + Br₂(l) Given:

A metal object is to be gold-plated by an electrolytic procedure using aqueous AuCl₃electrolyte. How much gold may be deposited in 3.0 min by a constant current of 10. A?

How much charge must pass through an electrolytic cell to reduce 0.44 mol Ca²⁺ion to calcium metal?

What is the equilibrium constant at 25°C for the following reaction? (R = 8.314 J/K • mol, F = 96,500 C • mol^-1)