Chemistry 9701 · AS & A Level · Electrochemistry

Electrochemistry — practice question

(a)[1]

State the substances released at the anode and at the cathode in the electrolysis of saturated $\text{KCl}(aq)$.

(b)[3]

During the electrolysis of dilute sulfuric acid, oxygen is produced at the anode. Dilute sulfuric acid is electrolysed for $15.0$ minutes with a current of $0.750\,\text{A}$. Calculate the volume of oxygen produced under room conditions.

(c(i))[1]

State the $E^\circ$ values for chlorine, bromine and iodine when each is acting as an oxidising agent.

(c(ii))[3]

Decide which of chlorine, bromine and iodine will react with a solution of $\text{Sn}^{2+}(aq)$ under standard conditions. Justify your answer. Include a relevant equation in your response.

(c(iii))[1]

Excess chlorine is added to a solution of acidified $\text{Mn}^{2+}(aq)$ under standard conditions. Give the formula of the manganese-containing product formed in this reaction.

(d(i))[1]

An electrochemical cell may be formed by linking an $\text{Fe}^{3+}/\text{Fe}^{2+}$ half-cell with an $\text{S}_2\text{O}_8^{2-}/\text{SO}_4^{2-}$ half-cell under standard conditions. Calculate the standard cell potential of this electrochemical cell.

(d(ii))[1]

State the material that should be used for the electrode in each half-cell: in the $\text{Fe}^{3+}/\text{Fe}^{2+}$ half-cell; in the $\text{S}_2\text{O}_8^{2-}/\text{SO}_4^{2-}$ half-cell.

(d(iii))[1]

Describe one change to each half-cell that would raise the cell potential. The temperature must stay at $298\,\text{K}$.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: chlorine and hydrogen

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