Using K_w = 10^-14 at 298 K, the standard potential of the half reaction 2H2O + 2e- -> H2 + 2OH- is closest to

JEE Main levelSingle correct optionDifficulty 2 of 3ec04

Using $K_{w} = 1 0^{- 14}$ at 298 K, the standard potential of the half reaction $2 H X_{2} O + 2 e X^{-} H X_{2} + 2 OH X^{-}$ is closest to

The half reaction is the hydrogen electrode at

[OH X^{-}] = 1 M

, i.e.

[H X^{+}] = 1 0^{- 14} M

E = 0 - 0.0591 lo g \frac{1}{[ H X ^{+} ]} = - 0.0591 \times 14 = - 0.827 V

. The value

- 0.414 V

corresponds to pH 7, not standard conditions.