Chemistry 9701 · AS & A Level · Electrochemistry

Electrochemistry — practice question

An electrochemical cell is made up of one half-cell that contains $ ext{V}^{3+} ext{(aq)}$ and $ ext{V}^{2+} ext{(aq)}$ ions, together with a second half-cell that contains $ ext{VO}_2^+ ext{(aq)}$ and $ ext{VO}^{2+} ext{(aq)}$ ions.
(a(i))[1]

Calculate a value for the $E^\circ_{\text{cell}}$ using data from the Data Booklet.

(a(ii))[1]

Write the ionic equation for the cell reaction.

(a(iii))[2]

Draw a fully labelled diagram of the apparatus you could use to measure the potential of this cell. Include the necessary chemicals.

(b)[3]

Use data from the Data Booklet to predict whether a reaction is likely to occur when the following pairs of aqueous solutions are mixed. If a reaction happens, write an equation for it and calculate the $E^\circ_{\text{cell}}$. $\bullet$ $ ext{V}^{2+} ext{(aq)}$ and $ ext{Sn}^{4+} ext{(aq)}$ $\bullet$ $ ext{VO}_2^+ ext{(aq)}$ and $ ext{Fe}^{3+} ext{(aq)}$

(b(i))[3]

Consider the aqueous solutions $\text{V}^{2+}(aq)$ and $\text{Sn}^{4+}(aq)$. Does a reaction occur? Write the equation, if any, and calculate $E^{\circ}_{cell}$.

(b(ii))[3]

Consider the aqueous solutions $\text{VO}^{2+}(aq)$ and $\text{Fe}^{3+}(aq)$. Does a reaction occur? Write the equation, if any, and calculate $E^{\circ}_{cell}$.

Worked solution & mark scheme

This 13-mark question has a full step-by-step worked solution and mark scheme. One marking point: $E^\circ_{\text{cell}}=1.00-(-0.26)=+1.26\,\text{V}$.

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