A certain redox reaction in aqueous solution is written in its thermodynamically…

CHEMISTRY · Multi-part · A Level · Chemistry · Thermodynamics · Thermodynamics

Problem

A certain redox reaction in aqueous solution is written in its thermodynamically convenient form as MnO4−(aq)+8 H+(aq)+5 e−→Mn2+(aq)+4 H2O(ℓ)\mathrm{MnO_4^-(aq) + 8\,H^+(aq) + 5\,e^- \rightarrow Mn^{2+}(aq) + 4\,H_2O(\ell)} At 298\,K the standard Gibbs free-energy change for this reaction is ΔG1∘=−215  kJ mol−1\Delta G^\circ_1 = -215\;\text{kJ\,mol}^{-1}. (a) Calculate the standard Gibbs free-energy change, ΔG2∘\Delta G^\circ_2, for the reaction written with all stoichiometric coefficients doubled. (b) Calculate ΔG3∘\Delta G^\circ_3 for the reaction written in the reverse direction relative to the original equation. (c) Based on the values obtained in parts (a) and (b), determine for each rewritten reaction whether products or reactants are favored at equilibrium. Justify your answers briefly.

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