Question 1

Which of the following correctly describes the notation for a voltaic cell where hydrogen gas is oxidized at the anode and chlorine gas is reduced at the cathode, both at standard conditions?

Accepted Answer

$\mathrm{Pt} | \mathrm{H}_2(1.0\ \mathrm{atm}) | \mathrm{H}^+(1.0\ \mathrm{M}) || \mathrm{Cl}_2(1.0\ \mathrm{atm}) | \mathrm{Cl}^-(1.0\ \mathrm{M}) | \mathrm{Pt}$

Question 2

A battery in a flashlight has reached equilibrium for all its electrochemical reactions. What happens when you turn on the flashlight?

Accepted Answer

No current flows and the flashlight does not light up.

Question 3

Which of the following statements about the Nernst equation is correct?

Accepted Answer

It shows that the cell potential decreases as the reaction quotient $Q$ increases.

Question 4

Given the following half-reactions and their standard reduction potentials:

$\mathrm{Al}^{3+} + 3e^- \rightarrow \mathrm{Al}(s)\ \ \ E^\circ = -1.66\ \mathrm{V}$

$\mathrm{Cu}^{2+} + 2e^- \rightarrow \mathrm{Cu}(s)\ \ \ E^\circ = 0.34\ \mathrm{V}$

Which metal will be oxidized in a redox reaction between aluminum and copper?

Accepted Answer

Aluminum will be oxidized and copper will be reduced.

Question 5

Which of the following best explains why lithium is used in pacemaker batteries?

Accepted Answer

Lithium has a very negative standard reduction potential, providing a high cell voltage and energy density.

Question 6

A zinc-carbon dry cell battery performs poorly in cold weather primarily because:

Accepted Answer

The rate of the electrochemical reactions decreases, reducing the current output.

Question 7

Which of the following is the correct Nernst equation for a cell at 25°C?

Accepted Answer

$E_{\mathrm{cell}} = E_{\mathrm{cell}}^\circ - \frac{0.02568}{n} \ln Q$

Question 8

Which of the following is NOT a component of a typical voltaic cell?

Accepted Answer

A heating element to maintain temperature.

Question 9

In a hydrogen-oxygen fuel cell, what is the overall reaction?

Accepted Answer

$2\mathrm{H}_2(g) + \mathrm{O}_2(g) \rightarrow 2\mathrm{H}_2\mathrm{O}(l)$

Question 10

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

Accepted Answer

It allows the flow of ions to maintain electrical neutrality in the solutions.

Question 11

Which of the following statements about standard cell potential ($E_{\mathrm{cell}}^\circ$) is correct?

Accepted Answer

It is calculated using standard reduction potentials for the cathode and anode.

Question 12

Which of the following is a reason why alkaline batteries perform better than zinc-carbon batteries in cold weather?

Accepted Answer

The alkaline electrolyte (KOH) remains conductive at lower temperatures.

Question 13

Which of the following equations correctly relates the standard cell potential to the equilibrium constant $K$ at 25°C?

Accepted Answer

$E_{\mathrm{cell}}^\circ = \frac{0.0592}{n} \log K$

Question 14

Which of the following best explains why a 'heavy-duty' zinc-carbon battery has a longer output life than a regular one?

Accepted Answer

The thicker zinc can provides more material for oxidation, increasing the battery's capacity.

Question 15

Which of the following is a practical application of measuring $E_{\mathrm{cell}}$ in a laboratory?

Accepted Answer

Determining the pH of a solution using a glass electrode.

Question 16

Which of the following statements about fuel cells is correct?

Accepted Answer

They require a continuous supply of reactants to generate electricity.

Question 17

Which of the following is true regarding the relationship between $\Delta G$ and $E_{\mathrm{cell}}$?

Accepted Answer

$\Delta G = -nFE_{\mathrm{cell}}$

Question 18

Which of the following would increase the cell potential of a voltaic cell according to the Nernst equation?

Accepted Answer

Decreasing the concentration of products relative to reactants.

Question 19

Which of the following is a reason why zinc-carbon batteries are not suitable for long-term medical implants like pacemakers?

Accepted Answer

They have a high self-discharge rate and are prone to corrosion.

Electrochemistry: Cell Potentials, Voltaic Cells, and Applications

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