Question 1

Which of the following best explains why a hydrogen fuel cell produces water as its only product?

Accepted Answer

Hydrogen is oxidized at the anode and oxygen is reduced at the cathode, combining to form water.

Question 2

Why does a zinc-carbon dry cell battery perform poorly in cold weather?

Accepted Answer

The reaction kinetics slow down, decreasing the battery's voltage output.

Question 3

Which of the following is a key advantage of lithium-iodine batteries for use in pacemakers?

Accepted Answer

They have high reliability and last for about ten years at low current.

Question 4

In a lead storage battery, what is the overall cell reaction during discharge?

Accepted Answer

$$\mathrm{Pb(s) + $$PbO_2$$(s) + 2H_2SO_4(aq) \rightarrow 2PbSO_4(s) + 2H_2O(l)}$$

Question 5

Which process is used to protect underground steel pipelines from corrosion?

Accepted Answer

Connecting the pipeline to a more active metal such as magnesium, making the pipeline the cathode.

Question 6

What is the main difference between a voltaic (galvanic) cell and an electrolytic cell?

Accepted Answer

A voltaic cell produces electricity from a spontaneous reaction, while an electrolytic cell uses electricity to drive a nonspontaneous reaction.

Question 7

During the electrolysis of molten sodium chloride in a Downs cell, what are the products at the anode and cathode?

Accepted Answer

Anode: $$\mathrm{Cl_2$(g)}$$; Cathode: $$\mathrm{Na(l)}$$

Question 8

Which of the following best describes the role of overpotential in electrochemistry?

Accepted Answer

It is the difference between the theoretical and observed cell voltage due to kinetic and other effects.

Question 9

Why is lithium used in batteries for medical implants such as pacemakers?

Accepted Answer

Lithium provides a high energy density and stable voltage at low current, making batteries lightweight and long-lasting.

Question 10

Which reaction occurs at the cathode during the rusting of iron in the presence of water and oxygen?

Accepted Answer

$$\mathrm{O_2$(g) + 2H_2O(l) + 4e^- \rightarrow 4OH^-(aq)}$$

Question 11

A battery is placed in a flashlight, but all the electrochemical reactions have reached equilibrium. What will happen when the flashlight is turned on?

Accepted Answer

No current will flow, so the flashlight will not turn on.

Question 12

Which of the following metals would be most suitable as a sacrificial anode for protecting iron from corrosion?

Accepted Answer

Magnesium

Question 13

During the electrolysis of an aqueous solution of sodium iodide ($$\mathrm{NaI}$$), which product forms at the anode?

Accepted Answer

$$\mathrm{I_2$(g)}$$

Question 14

Which of the following statements about the lead storage battery is correct?

Accepted Answer

It consists of multiple cells in series to provide a higher voltage.

Question 15

Which of the following best explains why corrosion is more severe in seawater than in freshwater?

Accepted Answer

Seawater contains more ions, increasing the conductivity and rate of electrochemical corrosion.

Question 16

Which of the following is a correct half-reaction for the anode in a nickel-cadmium cell during discharge?

Accepted Answer

$$\mathrm{Cd(s) + 2OH^-(aq) \rightarrow Cd(OH)_2(s) + 2e^-}$$

Question 17

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

Accepted Answer

Alkaline batteries use a paste electrolyte with better ion mobility at low temperatures.

Question 18

Which of the following equations correctly relates electric charge, current, and time?

Accepted Answer

$$\mathrm{Q = I 	imes t}$$

Question 19

In an electrolytic cell, which reaction will occur at the cathode?

Accepted Answer

The reduction reaction with the most positive $$E^\circ$$ value.

Question 20

In a redox reaction between copper and aluminum, which element is oxidized?

Accepted Answer

Aluminum, because it is a stronger reducing agent than copper.

Electrochemistry: Voltaic and Electrolytic Cells, Batteries, and Corrosion

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