Reduction Half Potential  [ENDORSED]

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Evelyn L 1H
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Joined: Fri Sep 29, 2017 7:05 am

Reduction Half Potential

Postby Evelyn L 1H » Wed Feb 21, 2018 4:18 pm

When we flip a reaction, for example flipping Ni2+ +2e- --> Ni to Ni --> Ni2+ +2e- to show oxidation, why don't we flip the sign of the reduction half potential?

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Re: Reduction Half Potential  [ENDORSED]

Postby Chem_Mod » Wed Feb 21, 2018 4:36 pm

Keep in mind "standard reduction potential" specifically refers to the reduction form of the half-reaction expression, always. If you write the half-reaction as an oxidation, then yes, you technically do flip the sign, but you must not flip the sign if you are going to use the formula E°cell = E°cathode - E°anode. This formula is only true if standard reduction potentials are used.

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