Nernst Equation Applied to Half-Reactions?

[匿名]

2017-11-08 1:07 pm

The Nernst equation can be applied to half-reactions.
Calculate the reduction potential (at 25°C) of the half-cell MnO4- (9.00×10-2 M)/ Mn2+ (5.00×10-3 M) at pH = 7.00.
(The half-reaction is MnO4- + 8H+ + 5e- --> Mn2+ + 4H2O.)

回答 (1)

不用客氣

2017-11-08 3:35 pm

✔ 最佳答案

Refer to: http://mmsphyschem.com/tblSRP.pdf
The standard reduction potential for MnO₄⁻ in an acidic medium is +1.51 V, i.e.
MnO₄⁻(aq) + 8H⁺(aq) + 5e⁻ → Mn²⁺(aq) + 4H₂O(l) …… E° = +1.51 V

Nernst equation : E = E° - {RT/(nF)} ln{[Mn²⁺]/([MnO₄⁻][H⁺]⁸)}

When [MnO₄⁻] = 9.00 × 10⁻² M, [Mn²⁺] = 5.00 × 10⁻³ M and [H⁺] = 1.00 × 10⁻⁷ M :
E = +1.51 - {8.314 × 298/(5 × 96500)} ln{(5.00 × 10⁻³)/[(9.00 × 10⁻²)(1.00 × 10⁻⁷)⁸]} V = +0.86 V

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