Question

In the electrolysis of aqueous $NaCl$ solution, side reactions taking place are :

(I) $2O{H}^{-}+C{l}_2\to 2OC{l}^{-}+H_{2}O$

(II) $2Na+2H_{2}O\to 2NaOH+H_2$

(III) $4O{H}^{-}\to O_2+2H_2+4e^{-}$

Select the correct alternate :

• A. (I) and (III)
• B. (II) and (III)
• C. (I) and (II)
• D. (I), (II), and (III)

Answer 1

The correct option is A (I) and (III)

In the electrolysis of aqueous $NaCl$ solution, side reactions taking place are :
(I) $2O{H}^{-}+C{l}_2\to 2OC{l}^{-}+H_{2}O$
(II) $4O{H}^{-}\to O_2+2H_2+4e^{-}$
However the reaction (II)$2Na+2H_{2}O\to 2NaOH+H_2$ does not occur.
Sodium is not present in the solution as the reduction of $N{a}^{+}$ will not occur due to higher SRP for water than for $N{a}^{+}$. Hence, at the cathode, water is reduced to hydrogen gas.