Chemistry 9701 · AS & A Level · Electrochemistry

Electrochemistry — practice question

(a(i))[1]

Define the meaning of the term standard cell potential, $E^\circ_{\text{cell}}$.

(a(ii))[1]

The incomplete diagram below shows apparatus that may be used to measure the $E^\circ_{\text{cell}}$ for a cell made from the $\text{Fe}^{3+}/\text{Fe}^{2+}$ and $\text{Ag}^+/\text{Ag}$ half-cells. Finish the diagram and label any components you add.

(a(iii))[3]

Identify the substances represented by components A-D.

(b(i))[1]

Use $E^\circ$ values to construct an equation for the cell reaction that occurs if the two electrodes in (a) are joined by a wire and the circuit is completed.

(b(ii))[2]

A different electrochemical cell was arranged using $0.31\,\text{mol dm}^{-3}\,\text{Ag}^+(aq)$ rather than the standard Ag solution. Use the Nernst equation, $E = E^\circ + 0.059\log[\text{Ag}^+(aq)]$, and the relevant $E^\circ$ values to calculate the revised $E_{\text{cell}}$ for this experiment.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: The standard cell potential is the emf for a cell assembled from two half-cells under standard conditions (for example $298\,\text{K}$, $1\,\text{mol dm}^{-3}$).

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