Question 1

Which statement correctly describes the difference between a galvanic (voltaic) cell and an electrolytic cell?

Accepted Answer

In a galvanic cell, electricity is generated by a spontaneous redox reaction and $E_{cell} > 0$.

Question 2

What is the function of the salt bridge in an electrochemical cell?

Accepted Answer

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

Question 3

Given the cell notation: $\mathrm{Zn}(s) | \mathrm{Zn}^{2+}(aq) || \mathrm{Cu}^{2+}(aq) | \mathrm{Cu}(s)$, which species is oxidized and which is reduced?

Accepted Answer

Zn is oxidized and Cu is reduced.

Question 4

The standard hydrogen electrode (SHE) is used as a reference in measuring electrode potentials. What is the standard electrode potential of SHE?

Accepted Answer

$E^{\circ} = 0.00\ \mathrm{V}$

Question 5

Which of the following half-reactions has the greatest tendency to be reduced under standard conditions?

Accepted Answer

$\mathrm{H}_2O_2 + 2H^+ + 2e^- \rightarrow 2\mathrm{H}_2O\ \ \ E^{\circ} = +1.77\ \mathrm{V}$

Question 6

Calculate the standard cell potential for a cell composed of $\mathrm{Pb}^{2+}/\mathrm{Pb}$ ($E^{\circ} = -0.13\ \mathrm{V}$) and $\mathrm{Ca}^{2+}/\mathrm{Ca}$ ($E^{\circ} = -2.84\ \mathrm{V}$), with $\mathrm{Pb}^{2+}/\mathrm{Pb}$ as the cathode.

Accepted Answer

$E_{cell}^{\circ} = +2.71\ \mathrm{V}$

Question 7

Which equation correctly relates the standard cell potential $E_{cell}^{\circ}$ to the standard Gibbs free energy change $\Delta G^{\circ}$?

Accepted Answer

$\Delta G^{\circ} = -nFE_{cell}^{\circ}$

Question 8

A current of 0.452 A is passed through molten $\mathrm{CaCl}_2$ for 1.50 hours. How many moles of electrons are transferred? (Faraday's constant $F = 96485\ \mathrm{C/mol}$)

Accepted Answer

0.0253 mol

Question 9

Which of the following statements about electrolysis is correct?

Accepted Answer

Electrolysis requires an external source of electricity to drive a non-spontaneous reaction.

Question 10

If $E_{cell}^{\circ} > 0$, what can be concluded about the cell reaction under standard conditions?

Accepted Answer

The reaction is spontaneous.

Question 11

Which of the following is the correct Nernst equation for calculating the cell potential at non-standard conditions?

Accepted Answer

$E_{cell} = E_{cell}^{\circ} - \dfrac{RT}{nF} \ln Q$

Question 12

In the cell $\mathrm{Zn}(s) | \mathrm{Zn}^{2+}(aq) || \mathrm{Cu}^{2+}(aq) | \mathrm{Cu}(s)$, what is the direction of electron flow?

Accepted Answer

From Zn to Cu through the external circuit.

Question 13

Which process occurs at the cathode in a galvanic cell?

Accepted Answer

Reduction

Question 14

A cell is constructed with $\mathrm{Fe}^{3+}/\mathrm{Fe}^{2+}$ ($E^{\circ} = +0.771\ \mathrm{V}$) and $\mathrm{I}_2/\mathrm{I}^-$ ($E^{\circ} = +0.535\ \mathrm{V}$). Can $\mathrm{Fe}^{3+}$ oxidize $\mathrm{I}^-$ to $\mathrm{I}_2$ under standard conditions?

Accepted Answer

Yes, because $E_{cell}^{\circ} > 0$.

Question 15

Which of the following best describes the relationship between the equilibrium constant $K$ and the standard cell potential $E_{cell}^{\circ}$?

Accepted Answer

$E_{cell}^{\circ} = \dfrac{RT}{nF} \ln K$

Question 16

During the electrolysis of molten $\mathrm{CaCl}_2$, which reaction occurs at the cathode?

Accepted Answer

$\mathrm{Ca}^{2+} + 2e^- \rightarrow \mathrm{Ca}(s)$

Question 17

If a current of 2.00 A is passed through an electrolytic cell for 30 minutes, how many coulombs of charge have passed through the cell?

Accepted Answer

3600 C

Question 18

Which industrial process is NOT typically associated with electrolysis?

Accepted Answer

Fractional distillation of crude oil

Electrochemistry: Principles, Cells, and Applications

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