24. Calculate the standard Gibbs free energy change () for the overall rusting reaction of iron: . G — Electrochemistry Chemistry Question
Question
24. Calculate the standard Gibbs free energy change ($\Delta G^\circ$) for the overall rusting reaction of iron: $2Fe(s) + O_2(g) + 4H^+(aq) \rightarrow 2Fe^{2+}(aq) + 2H_2O(l)$. Given $E^\circ_{Fe^{2+}/Fe} = -0.44 V$ and $E^\circ_{O_2/H_2O} = +1.23 V$.
Answer: B
💡 Solution & Explanation
$E^\circ_{cell} = 1.23 - (-0.44) = 1.67 V$. The balanced reaction involves 4 electrons (2 Fe atoms oxidize). $\Delta G^\circ = -nFE^\circ = -4 \times 96500 \times 1.67 = -644620 J/mol = -644.6 kJ/mol$.
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