Question 1

Oxidation occurs at the cathode of a galvanic cell, but at the anode of an electrolytic cell.

Accepted Answer

A) True 
 B)False

Question 2

In the shorthand notation for cells, a single vertical line represents a salt bridge.

Accepted Answer

A) True 
 B)False

Question 3

A voltaic cell consists of a Mn/Mn2+ electrode (E° = -1.18 V) and a Fe/Fe2+ electrode (E° = -0.44 V). Calculate [Fe2+] if [Mn2+] = 0.050 M and E cell = 0.78 V at 25°C.

Accepted Answer

A)  0.040 M 
B)  0.24 M 
C)  1.1 M 
D)  1.8 M 
E)  None of these choices are correct. 
A)  0.040 M 
B)  0.24 M 
C)  1.1 M 
D)  1.8 M 
E)  None of these choices are correct.

Question 4

Consider the following balanced redox reaction 3CuO(s) + 2NH3(aq) → N2(g) + 3H2O(l) + 3Cu(s)
Which of the following statements is true?

Accepted Answer

A)  CuO(s) is the oxidizing agent and copper is reduced. 
B)  CuO(s) is the oxidizing agent and copper is oxidized. 
C)  CuO(s) is the reducing agent and copper is oxidized. 
D)  CuO(s) is the reducing agent and copper is reduced. 
E)  CuO(s) is the oxidizing agent and N2(g) is the reducing agent. 
A)  CuO(s) is the oxidizing agent and copper is reduced. 
B)  CuO(s) is the oxidizing agent and copper is oxidized. 
C)  CuO(s) is the reducing agent and copper is oxidized. 
D)  CuO(s) is the reducing agent and copper is reduced. 
E)  CuO(s) is the oxidizing agent and N2(g) is the reducing agent.

Question 5

Calculate ΔG° for the reaction of iron(II) ions with one mole of permanganate ions. MnO4-(aq) + 8H+(aq) + 5e-   Mn2+(aq) + 4H2O(l) E° = 1.51 V
Fe3+(aq) + e-
    Fe2+(aq) E°= 0.77 V

Accepted Answer

A)  -71.4 kJ 
B)  -286 kJ 
C)  -357 kJ 
D)  -428 kJ 
E)  None of these choices are correct. 
A)  -71.4 kJ 
B)  -286 kJ 
C)  -357 kJ 
D)  -428 kJ 
E)  None of these choices are correct.

Question 6

When the following redox equation is balanced with smallest whole number coefficients, the coefficient for the hydrogen sulfate ion will be Al(s) + HSO4(aq) + OH-(aq) → Al2O3(s) + S2-(aq) + H2O(l)

Accepted Answer

A)  1. 
B)  3. 
C)  4. 
D)  8. 
E)  None of these choices are correct. 
A)  1. 
B)  3. 
C)  4. 
D)  8. 
E)  None of these choices are correct.

Question 7

A voltaic cell has a standard cell potential equal to 0.74 V. If the standard electrode (reduction) potential for the anode is -0.22 V, what is the standard electrode potential for the cathode?

Accepted Answer

A)  0.96 V 
B)  0.52 V 
C)  -0.52 V 
D)  -0.96 V 
E)  Need to know the cell reaction in order to calculate the answer. 
A)  0.96 V 
B)  0.52 V 
C)  -0.52 V 
D)  -0.96 V 
E)  Need to know the cell reaction in order to calculate the answer.

Question 8

If the electrodes of a voltaic cell are connected with an external wire, electrons will flow in this wire from the cathode to the anode.

Accepted Answer

A) True 
 B)False

Question 9

Examine the following half-reactions and select the strongest reducing agent among the species listed. HgO(s) + H2O(l) + 2e-
    Hg(l) + 2OH-(aq) E°= 0.0977 V
Zn(OH)2(s) + 2e-
    Zn(s) + 2OH-(aq) E° = -1.25 V
Ag2O(s) + H2O(l) + 2e-
    Ag(s) + 2OH-(aq) E° = 0.342 V
B(OH)3(aq) + 7H+(aq) + 8e-
    BH4-(aq) + 3H2O(l) E° = -0.481 V

Accepted Answer

A)  Hg(l) 
B)  Zn(s) 
C)  Ag(s) 
D)  BH4-(aq) 
E)  Zn(OH)2(s) 
A)  Hg(l) 
B)  Zn(s) 
C)  Ag(s) 
D)  BH4-(aq) 
E)  Zn(OH)2(s)

Question 10

In a fuel cell, an external source of electrical power is used to drive a nonspontaneous reaction in which a fuel is produced.

Accepted Answer

A) True 
 B)False

Question 11

Calculate E°cell and indicate whether the overall reaction shown is spontaneous or nonspontaneous. I2(s) + 2e-
    2I-(aq) E° = 0.53 V
Cr3+(aq) + 3e-
    Cr(s) E° = -0.74 V
Overall reaction:
2Cr(s) + 3I2(s) → 2Cr3+(aq) + (aq) + 6I-(aq)

Accepted Answer

A)  E°cell = -1.27 V, spontaneous 
B)  E° cell = -1.27 V, nonspontaneous 
C)  E° cell = 1.27 V, spontaneous 
D)  E° cell = 1.27 V, nonspontaneous 
E)  E° cell = 1.54 V, spontaneous 
A)  E°cell = -1.27 V, spontaneous 
B)  E° cell = -1.27 V, nonspontaneous 
C)  E° cell = 1.27 V, spontaneous 
D)  E° cell = 1.27 V, nonspontaneous 
E)  E° cell = 1.54 V, spontaneous

Question 12

Which one of the following pairs of substances could be used to construct a single redox electrode (i.e., they have an element in common, but in different oxidation states)?

Accepted Answer

A)  HCl and Cl- 
B)  H+ and OH- 
C)  H2O and H+ 
D)  Fe3+ and Fe2O3 
E)  MnO2 and Mn2+ 
A)  HCl and Cl- 
B)  H+ and OH- 
C)  H2O and H+ 
D)  Fe3+ and Fe2O3 
E)  MnO2 and Mn2+

Question 13

A current of 250. A flows for 24.0 hours at an anode where the reaction occurring is Mn2+(aq) + 2H2O(l) → MnO2(s) + 4H+(aq) + 2e- What mass of MnO2 is deposited at this anode?

Accepted Answer

A)  19.5 kg 
B)  12.9 kg 
C)  4.87 kg 
D)  2.43 kg 
E)  None of these choices are correct. 
A)  19.5 kg 
B)  12.9 kg 
C)  4.87 kg 
D)  2.43 kg 
E)  None of these choices are correct.

Question 14

In the shorthand notation for cells, a double vertical line is used to separate the reduced and oxidized forms of a redox couple.

Accepted Answer

A) True 
 B)False

Question 15

A voltaic cell prepared using aluminum and nickel has the following cell notation. Al(s) | Al3+(aq) || Ni2+(aq) | Ni(s)
Which of the following represents the correctly balanced spontaneous reaction equation for the cell?

Accepted Answer

A)  Ni2+(aq) + Al(s) → Al3+(aq) + Ni(s) 
B)  3Ni2+(aq) + 2Al(s) → 2Al3+(aq) + 3Ni(s) 
C)  Ni(s) + Al3+(aq) → Ni2+(aq) + Al(s) 
D)  3Ni(s) + 2Al3+(aq) → 3Ni2+(aq) + 2Al(s) 
E)  None of these choices are correct. 
A)  Ni2+(aq) + Al(s) → Al3+(aq) + Ni(s) 
B)  3Ni2+(aq) + 2Al(s) → 2Al3+(aq) + 3Ni(s) 
C)  Ni(s) + Al3+(aq) → Ni2+(aq) + Al(s) 
D)  3Ni(s) + 2Al3+(aq) → 3Ni2+(aq) + 2Al(s) 
E)  None of these choices are correct.

Question 16

Predict the products of the cell reaction when a molten salt mixture of sodium bromide and calcium fluoride is electrolyzed (spectator ions are not considered to be products).

Accepted Answer

A)  calcium and bromine 
B)  sodium and fluorine 
C)  calcium bromide 
D)  calcium and fluorine 
E)  sodium and bromine 
A)  calcium and bromine 
B)  sodium and fluorine 
C)  calcium bromide 
D)  calcium and fluorine 
E)  sodium and bromine

Question 17

A voltaic cell consists of a Hg/Hg22+ electrode (E° = 0.85 V) and a Sn/Sn2+ electrode (E° = -0.14 V). Calculate [Sn2+] if [Hg22+] = 0.24 M and Ecell = 1.04 V at 25°C.

Accepted Answer

A)  0.0001 M 
B)  0.0007 M 
C)  0.005 M 
D)  0.03 M 
E)  0.05 M 
A)  0.0001 M 
B)  0.0007 M 
C)  0.005 M 
D)  0.03 M 
E)  0.05 M

Question 18

If the equilibrium constant Kc is greater than 1 for a given reaction, predict the signs of ΔG° and E° at the same temperature.

Accepted Answer

A)  ΔG° > 0; E° > 0 
B)  ΔG°  0; E°  0 
E)  Cannot predict - it depends on the temperature. 
A)  ΔG° > 0; E° > 0 
B)  ΔG°  0; E°  0 
E)  Cannot predict - it depends on the temperature.

Question 19

Examine the following half-reactions and select the strongest oxidizing agent among the substances. [PtCl4]2-(aq) + 2e-
    Pt(s) + 4Cl-(aq) E° = 0.755 V
RuO4(s) + 8H+(aq) + 8e-
    Ru(s) + 4H2O(l) E° = 1.038 V
FeO42-(aq) + 8H+(aq) + 3e-
    Fe3+(aq) + 4H2O(l) E° = 2.07 V
H4XeO6(aq) + 2H+(aq) + 2e-
    XeO3(aq) + 3H2O(l) E° = 2.42 V

Accepted Answer

A)  [PtCl4]2-(aq) 
B)  RuO4(s) 
C)  HFeO4- (aq) 
D)  H4XeO6(aq) 
E)  Cl-(aq) 
A)  [PtCl4]2-(aq) 
B)  RuO4(s) 
C)  HFeO4- (aq) 
D)  H4XeO6(aq) 
E)  Cl-(aq)

Question 20

For the reaction occurring in a voltaic (galvanic) cell, ΔG > 0.

Accepted Answer

A) True 
 B)False

Exam 21: Electrochemistry Chemical Change and Electrical Work

Oxidation occurs at the cathode of a galvanic cell, but at the anode of an electrolytic cell.

In the shorthand notation for cells, a single vertical line represents a salt bridge.

A voltaic cell consists of a Mn/Mn2+ electrode (E° = -1.18 V) and a Fe/Fe2+ electrode (E° = -0.44 V). Calculate [Fe2+] if [Mn2+] = 0.050 M and E cell = 0.78 V at 25°C.

Consider the following balanced redox reaction 3CuO(s) + 2NH3(aq) → N2(g) + 3H2O(l) + 3Cu(s) Which of the following statements is true?

Calculate ΔG° for the reaction of iron(II) ions with one mole of permanganate ions. MnO4-(aq) + 8H+(aq) + 5e- Mn2+(aq) + 4H2O(l) E° = 1.51 V Fe3+(aq) + e- Fe2+(aq) E°= 0.77 V

When the following redox equation is balanced with smallest whole number coefficients, the coefficient for the hydrogen sulfate ion will be Al(s) + HSO4(aq) + OH-(aq) → Al2O3(s) + S2-(aq) + H2O(l)

A voltaic cell has a standard cell potential equal to 0.74 V. If the standard electrode (reduction) potential for the anode is -0.22 V, what is the standard electrode potential for the cathode?

If the electrodes of a voltaic cell are connected with an external wire, electrons will flow in this wire from the cathode to the anode.

In a fuel cell, an external source of electrical power is used to drive a nonspontaneous reaction in which a fuel is produced.

Calculate E°cell and indicate whether the overall reaction shown is spontaneous or nonspontaneous. I2(s) + 2e- 2I-(aq) E° = 0.53 V Cr3+(aq) + 3e- Cr(s) E° = -0.74 V Overall reaction: 2Cr(s) + 3I2(s) → 2Cr3+(aq) + (aq) + 6I-(aq)

Which one of the following pairs of substances could be used to construct a single redox electrode (i.e., they have an element in common, but in different oxidation states)?

A current of 250. A flows for 24.0 hours at an anode where the reaction occurring is Mn2+(aq) + 2H2O(l) → MnO2(s) + 4H+(aq) + 2e- What mass of MnO2 is deposited at this anode?

In the shorthand notation for cells, a double vertical line is used to separate the reduced and oxidized forms of a redox couple.

A voltaic cell prepared using aluminum and nickel has the following cell notation. Al(s) | Al3+(aq) || Ni2+(aq) | Ni(s) Which of the following represents the correctly balanced spontaneous reaction equation for the cell?

Predict the products of the cell reaction when a molten salt mixture of sodium bromide and calcium fluoride is electrolyzed (spectator ions are not considered to be products).

A voltaic cell consists of a Hg/Hg22+ electrode (E° = 0.85 V) and a Sn/Sn2+ electrode (E° = -0.14 V). Calculate [Sn2+] if [Hg22+] = 0.24 M and Ecell = 1.04 V at 25°C.

If the equilibrium constant Kc is greater than 1 for a given reaction, predict the signs of ΔG° and E° at the same temperature.

For the reaction occurring in a voltaic (galvanic) cell, ΔG > 0.

Keys to Studying Chemistry Definitions, Units, and Problem Solving

The Components of Matter

Stoichiometry of Formulas and Equations

Three Major Classes of Chemical Reactions

Gases and the Kinetic-Molecular Theory

Thermochemistry Energy Flow and Chemical Change

Quantum Theory and Atomic Structure

Electron Configuration and Chemical Periodicity

Models of Chemical Bonding

The Shapes of Molecules

Theories of Covalent Bonding

Intermolecular Forces Liquids, Solids, and Phase Changes

The Properties of Mixtures Solutions and Colloids

Periodic Patterns in the Main-Group Elements

Organic Compounds and the Atomic Properties of Carbon

Kinetics Rates and Mechanisms of Chemical Reactions

Equilibrium the Extent of Chemical Reactions

Acid-Base Equilibria

Ionic Equilibria in Aqueous Systems

Thermodynamics Entropy, Free Energy, and Reaction Direction

The Elements in Nature and Industry

Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

A voltaic cell consists of a Mn/Mn²⁺ electrode (E° = -1.18 V) and a Fe/Fe²⁺ electrode (E° = -0.44 V). Calculate [Fe²⁺] if [Mn²⁺] = 0.050 M and E_cell = 0.78 V at 25°C.

Consider the following balanced redox reaction 3CuO(s) + 2NH₃(aq) → N₂(g) + 3H₂O(l) + 3Cu(s) Which of the following statements is true?

Calculate ΔG° for the reaction of iron(II) ions with one mole of permanganate ions. MnO₄-(aq) + 8H+(aq) + 5e- Mn₂+(aq) + 4H₂O(l) E° = 1.51 V Fe³⁺(aq) + e^- Fe²⁺(aq) E°= 0.77 V

When the following redox equation is balanced with smallest whole number coefficients, the coefficient for the hydrogen sulfate ion will be Al(s) + HSO₄(aq) + OH_-(aq) → Al₂O₃(s) + S_2-(aq) + H₂O(l)

Calculate E°cell and indicate whether the overall reaction shown is spontaneous or nonspontaneous. I₂(s) + 2e^- 2I^-(aq) E° = 0.53 V Cr³⁺(aq) + 3e^- Cr(s) E° = -0.74 V Overall reaction: 2Cr(s) + 3I₂(s) → 2Cr³⁺(aq) + (aq) + 6I^-(aq)

A current of 250. A flows for 24.0 hours at an anode where the reaction occurring is Mn²⁺(aq) + 2H₂O(l) → MnO₂(s) + 4H⁺(aq) + 2e^- What mass of MnO2 is deposited at this anode?

A voltaic cell prepared using aluminum and nickel has the following cell notation. Al(s) | Al³⁺(aq) || Ni²⁺(aq) | Ni(s) Which of the following represents the correctly balanced spontaneous reaction equation for the cell?

A voltaic cell consists of a Hg/Hg2²⁺ electrode (E° = 0.85 V) and a Sn/Sn²⁺ electrode (E° = -0.14 V). Calculate [Sn²⁺] if [Hg₂²⁺] = 0.24 M and E_cell = 1.04 V at 25°C.

If the equilibrium constant K_c is greater than 1 for a given reaction, predict the signs of ΔG° and E° at the same temperature.