Chemistry 9701 · AS & A Level · Electrochemistry

Electrochemistry — practice question

(a)[1]

Identify the species released at the anode and at the cathode when aqueous sodium sulfate, $\text{Na}_2\text{SO}_4(aq)$, is electrolysed. Anode: \ldots Cathode: \ldots

(b)[4]

During electrolysis of molten sodium chloride, chlorine is released at the anode and sodium at the cathode. A sample of molten sodium chloride is electrolysed for 1.50 hours at a current of 4.50 A. Calculate the volume of chlorine and the mass of sodium released under room conditions.

(c(i))[4]

The standard electrode potential, $E^\circ$, for the reduction of $\text{MnO}_4^-(aq)$ to $\text{Mn}^{2+}(aq)$ in acid solution is given by $\text{MnO}_4^-(aq) + 8\text{H}^+(aq) + 5e^- \rightleftharpoons \text{Mn}^{2+}(aq) + 4\text{H}_2\text{O}(l)$, $E^\circ = +1.52\ \text{V}$. Draw the apparatus needed to measure the $E^\circ$ value of this half-cell. Your diagram should be fully labelled so that all apparatus, substances and conditions are identified.

(c(ii))[2]

Use the Data Booklet to identify a substance that could oxidise $\text{Mn}^{2+}$ ions to $\text{MnO}_4^-$ ions under standard conditions. Write an equation for the reaction.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: The anode produces $O_2$

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