Given the standard reduction potentials: $\text{Fe}^{3+}+e^- \rightarrow \text{Fe}^{2+}$ $E^{\circ}=+0.77\ \text{V}$ and $\text{Cu}^{2+}+2e^- \rightarrow \text{Cu}$ $E^{\circ}=+0.34\ \text{V}$. Construct a galvanic cell in which iron(III) ions are reduced and copper metal is oxidised. (i) Write the overall balanced redox equation, (ii) calculate the standard cell potential $E^{\circ}_{\text{cell}}$, and (iii) determine the equilibrium constant $K$ at $25^{\circ}\text{C}$. (Use $R=8.314\ \text{J mol}^{-1}\text{K}^{-1}$, $T=298\ \text{K}$, $F=96\,485\ \text{C mol}^{-1}$).

Question

Given the standard reduction potentials: $\text{Fe}^{3+}+e^- \rightarrow \text{Fe}^{2+}$   $E^{\circ}=+0.77\ \text{V}$ and $\text{Cu}^{2+}+2e^- \rightarrow \text{Cu}$   $E^{\circ}=+0.34\ \text{V}$. Construct a galvanic cell in which iron(III) ions are reduced and copper metal is oxidised. (i) Write the overall balanced redox equation, (ii) calculate the standard cell potential $E^{\circ}_{\text{cell}}$, and (iii) determine the equilibrium constant $K$ at $25^{\circ}\text{C}$. (Use $R=8.314\ \text{J mol}^{-1}\text{K}^{-1}$, $T=298\ \text{K}$, $F=96\,485\ \text{C mol}^{-1}$).

Accepted Answer

Overall equation: 2Fe^{3+}+Cu → 2Fe^{2+}+Cu^{2+}; E°cell = 0.43 V; K ≈ 3×10^{14}

Igcse Model Questions Vol1 2018 Chemistry Question 3

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