Chemistry 9701 · AS & A Level · Electrochemistry

Electrochemistry — practice question

The diagram below shows a partly completed experimental arrangement needed to determine the $E_{\text{cell}}$ of a cell made from the standard $\text{Cu}^{2+}/\text{Cu}$ electrode and an $\text{Ag}^+/\text{Ag}$ electrode.
(a(i))

State the chemical composition of solution A and electrode B.

(a(ii))[4]

Complete the diagram so that the entire experimental arrangement is shown.

(b(i))

The cell above is not under standard conditions because the [$\text{Ag}^+]$ in a saturated solution of $\text{AgCl}$ is far below $1.0\,\text{mol dm}^{-3}$. The $E_{\text{electrode}}$ is linked to [$\text{Ag}^+]$ by the equation below: $E_{\text{electrode}} = E^\circ_{\text{electrode}} + 0.06\,\log[\text{Ag}^+]$ Use the Data Booklet to work out $E^\circ_{\text{cell}}$ if the cell were operating under standard conditions.

(b(ii))

In the experiment above, $E_{\text{cell}}$ was recorded as $+0.17\,\text{V}$. Calculate $E_{\text{electrode}}$ for the $\text{Ag}^+/\text{Ag}$ electrode in this experiment.

(b(iii))[3]

Use equation 1 to calculate [$\text{Ag}^+$] in the saturated solution.

(c(i))[1]

Write an expression for $K_{sp}$ of silver sulfate, $\text{Ag}_2\text{SO}_4$, and include units.

(c(ii))[3]

Using a similar experimental arrangement to the one shown opposite, it is found that $[\text{Ag}^+]$ in a saturated solution of $\text{Ag}_2\text{SO}_4$ is $1.6 \times 10^{-2}\,\text{mol dm}^{-3}$. Calculate the value of $K_{sp}$ of silver sulfate.

(d)[4]

Describe how the colours of the silver halides, together with their relative solubilities in $\text{NH}_3\,(aq)$, may be used to tell apart solutions containing the halide ions $\text{Cl}^-$, $\text{Br}^-$ and $\text{I}^-.$

(e)[4]

Describe and explain the pattern in the solubilities of the sulfates of the elements in Group II.

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