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Given: E°Fe³⁺/Fe = -0.036 V E°Fe²⁺/Fe = -0.439 V The value of standard electrode potential for the change, Fe³⁺(aq) + e⁻ → Fe²⁺(aq) will be:

1. 0.385 V
2. 0.770 V
3. -0.270 V
4. -0.072 V

Correct answer: 0.770 V

Solution

For Fe3+/Fe2+: n*E = 3*E(Fe3+/Fe) - 2*E(Fe2+/Fe) = 3(-0.036) - 2(-0.439) = -0.108 + 0.878 = 0.770. With n = 1, E(Fe3+/Fe2+) = 0.770 V.

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