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Given that the standard reduction potential for F2 + 2e- -> 2F- equals 2.8 V, what is the standard reduction potential for the half reaction (1/2)F2 + e- -> F-?

1. 2.8 V
2. 1.4 V
3. -2.8 V
4. -1.4 V

Correct answer: 2.8 V

Solution

E° is an intensive quantity; it does not depend on the number of electrons or the stoichiometric coefficients of the balanced equation. Although delta-G° = -nFE° is extensive (it scales with n), E° itself is unchanged when the reaction is halved. So the value stays 2.8 V.

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