Three half–reactions are available under standard conditions

CHEMISTRY · Multi-part · A Level · Chemistry · Electrode potentials · Electrode potentials

Problem

Three half–reactions are available under standard conditions. I. ClO3−(aq)+6 H+(aq)+6 e−→Cl−(aq)+3 H2O(l)\text{ClO}_3^{-}(aq) + 6\,\text{H}^{+}(aq) + 6\,e^{-} \to \text{Cl}^{-}(aq) + 3\,\text{H}_2\text{O}(l)      E∘=+1.47 VE^\circ = +1.47\,\text{V} II. Fe3+(aq)+e−→Fe2+(aq)\text{Fe}^{3+}(aq) + e^{-} \to \text{Fe}^{2+}(aq)                     E∘=+0.77 VE^\circ = +0.77\,\text{V} III. Zn2+(aq)+2 e−→Zn(s)\text{Zn}^{2+}(aq) + 2\,e^{-} \to \text{Zn}(s)                     E∘=−0.76 VE^\circ = -0.76\,\text{V} The Faraday constant is F=9.65×104 C mol−1F = 9.65 \times 10^4\,\text{C mol}^{-1}. (a) Select one half–reaction to act as the cathode reduction and one to act as the anode oxidation so that the resulting galvanic cell has the maximum positive standard cell potential. Justify your selection. (b) Write the balanced overall reaction for the cell chosen in part (a), including physical states. (c) Determine Ecell∘E^\circ_{\text{cell}} for the overall reaction and state the corresponding value of nn. (d) Calculate ΔG∘\Delta G^\circ in kJ for the reaction as written in part (b). (e) Describe how replacing the anode selected in part (a) with the remaining unused half–reaction would affect both Ecell∘E^\circ_{\text{cell}} and ΔG∘\Delta G^\circ, and support your reasoning with appropriate numerical or qualitative arguments.

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