Question

During the electrolysis of aqueous solution of sodium chloride, pH of the electrolyte:

• A. remains constant
• B. gradually increases
• C. gradually decreases
• D. decreases first and then increases

Answer 1

The correct option is B gradually increases

S.R.P $=$ Standard Reduction Potential.

During electrolysis of aq. NaCl,
$H^{+}$ gets reduced as S.R.P of $H^{+}$ > S.R.P of $N{a}^{+}$.

Hence conc. of $H^{+}$ ion in the solution decreases.

$pH=-log\left[H^{+}\right]$ as $\left[H^{+}\right]$ decreases, $-log\left[H^{+}\right]$ increases.

So, pH increases.