Question 1

Which of the following statements about a Galvanic (Voltaic) cell is correct?

Accepted Answer

The anode is where oxidation occurs and it has a negative charge.

Question 2

Given the following standard reduction potentials:

$\mathrm{Cu^{2+} + 2e^- \rightarrow Cu(s)} \quad E^\circ = +0.337\ \mathrm{V}$

$\mathrm{Zn^{2+} + 2e^- \rightarrow Zn(s)} \quad E^\circ = -0.763\ \mathrm{V}$

Which species is the strongest oxidizing agent?

Accepted Answer

$\mathrm{Cu^{2+}}$

Question 3

A battery is constructed using the following half-reactions:

$\mathrm{Ag^+ (aq) + e^- \rightarrow Ag(s)} \quad E^\circ = +0.800\ \mathrm{V}$

$\mathrm{Cu^{2+} (aq) + 2e^- \rightarrow Cu(s)} \quad E^\circ = +0.337\ \mathrm{V}$

What is the standard cell potential ($E^\circ_{cell}$) for the battery, and is the reaction spontaneous?

Accepted Answer

$E^\circ_{cell} = +0.463\ \mathrm{V}$; the reaction is spontaneous.

Question 4

Which of the following best describes the relationship between $\Delta G^\circ$, $E^\circ_{cell}$, and $K$ for a spontaneous electrochemical reaction?

Accepted Answer

$\Delta G^\circ < 0$, $E^\circ_{cell} > 0$, $K > 1$

Question 5

In the line notation for a galvanic cell, which of the following is correct for a cell using zinc and copper electrodes in 1.0 M solutions?

Accepted Answer

$\mathrm{Zn(s)\ |\ Zn^{2+}(aq,\ 1.0\ M)\ ||\ Cu^{2+}(aq,\ 1.0\ M)\ |\ Cu(s)}$

Question 6

A student connects a copper electrode in $\mathrm{CuSO_4}$ solution and a zinc electrode in $\mathrm{ZnSO_4}$ solution with a salt bridge. Which direction do electrons flow through the external wire?

Accepted Answer

From zinc to copper

Question 7

Which of the following best explains why the half-reactions in a galvanic cell must be in separate containers?

Accepted Answer

To prevent direct electron transfer through the solution, which would short-circuit the cell.

Question 8

Given the following standard reduction potentials:

$\mathrm{Au^{3+} + 3e^- \rightarrow Au(s)} \quad E^\circ = +1.50\ \mathrm{V}$

$\mathrm{Ag^+ + e^- \rightarrow Ag(s)} \quad E^\circ = +0.80\ \mathrm{V}$

What is the standard cell potential ($E^\circ_{cell}$) for a battery constructed from these half-cells?

Accepted Answer

$E^\circ_{cell} = +0.70\ \mathrm{V}$

Question 9

Which of the following reactions is spontaneous under standard conditions?

Standard reduction potentials:
$\mathrm{Cu^{2+} + 2e^- \rightarrow Cu(s)} \quad +0.337\ \mathrm{V}$
$\mathrm{Zn^{2+} + 2e^- \rightarrow Zn(s)} \quad -0.763\ \mathrm{V}$

Accepted Answer

$\mathrm{Cu^{2+} (aq) + Zn(s) \rightarrow Cu(s) + Zn^{2+} (aq)}$

Question 10

Which of the following best describes what happens to the mass of the electrodes in a Cu-Zn galvanic cell as the cell operates?

Accepted Answer

The mass of the copper electrode increases and the mass of the zinc electrode decreases.

Question 11

Which of the following equations correctly relates the standard free energy change ($\Delta G^\circ$) to the standard cell potential ($E^\circ_{cell}$)?

Accepted Answer

$\Delta G^\circ = -nFE^\circ_{cell}$

Question 12

If a battery is 'dead,' which of the following is true about its cell potential and concentrations?

Accepted Answer

The cell potential is zero because the concentrations of reactants and products have reached equilibrium.

Question 13

Which of the following is the strongest reducing agent among the species below?

$\mathrm{Ni(s)}$, $\mathrm{I_2(aq)}$, $\mathrm{IO_3^-(aq)}$, $\mathrm{Ni^{2+}(aq)}$

Accepted Answer

$\mathrm{Ni(s)}$

Question 14

A spontaneous redox reaction in a galvanic cell creates electricity because:

Accepted Answer

Electrons flow from the anode to the cathode through the external circuit.

Question 15

Which of the following best describes the function of the salt bridge in a galvanic cell?

Accepted Answer

It maintains electrical neutrality by allowing ions to flow between the half-cells.

Question 16

If the standard cell potential ($E^\circ_{cell}$) for a reaction is negative, what can be concluded about the spontaneity of the reaction under standard conditions?

Accepted Answer

The reaction is non-spontaneous.

Question 17

Which of the following best describes what happens to $K$ (the equilibrium constant) for a redox reaction with a positive $E^\circ_{cell}$?

Accepted Answer

$K > 1$

Question 18

A battery is constructed using the following half-reactions:

$\mathrm{Fe^{3+} + e^- \rightarrow Fe^{2+}} \quad E^\circ = +0.77\ \mathrm{V}$

$\mathrm{Zn^{2+} + 2e^- \rightarrow Zn(s)} \quad E^\circ = -0.76\ \mathrm{V}$

What is the standard cell potential ($E^\circ_{cell}$) for the battery?

Accepted Answer

$E^\circ_{cell} = +1.53\ \mathrm{V}$

Galvanic Cells, Standard Reduction Potentials, and Electrochemical Cells

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