For, `I_(2) + 2e rarr 2I^(-)`, standard reduction potential `= +0.54` volt. For, `2Br^(-) rarr Br_(2) + 2e^(-)` standard oxidation potential `= -1.09` volt. For `Fe rarr F^(2+) + 2e^(-)`, standard oxidation potential `= +0.44` volt. Which of the follwoing reactions is non-spontaneous ?

Options

A. `Br_(2) + 2I^(-) rarr 2Br^(-) + I_(2)`
B. `Fe + Br_(2) rarr Fe^(2+) + 2Br^(-)`
C. `Fe + I_(2) rarr Fe^(2+) + 2I^(-)`
D. `I_(2) + 2Br^(-) rarr 2I^(-) + Br_(2)`

Answer

D

Explanation

`E^(@)` for reaction in `(d) = E_(OP_(Br))^(@) + E_(RP_(1))^(@)`
`= -1.09 + 0.54 = -0.55 V`
Since `E^(@)` is negative and thus reaction is non-spontaneous.