Brine is electrolysed by using inert electrodes. The reaction at anode is

Options

A. `Cl^(-)(aq) to 1//2 Cl_2(g) + e^(-) , E_("cell")= 1.36V`
B. `2H_2O (l) to O_2(g) + 4H^(+) (aq)^(+) 4e^(-) , E_("cell") = 1.23 V`
C. `Na^(+) (aq) + e^(-) to Na(s) , E_("cell") = 2.71V`
D. `H^(+)(aq) + e^(-) to 1//2 H_2(g) , E_("cell") = 0.00V`

Answer

A

Explanation

Although oxidation potential of `Cl^(-)` ion is higher than that of `H_2O`, yet oxidation of `Cl^(-)`ion takes place in preference to `H_2O`. This is because due to overvoltage of `O_2`, much higher potential is needed for oxidation of water.