Question

What will be $pH$ of aqueous solution of electrolyte in electrolytic cell during electrolysis of $CuS{O}_4\left(aq\right)$ between graphite electrodes?

• A. Data is insufficient
• B. $pH>7.0$
• C. $pH<7.0$
• D. $pH=7.0$

Answer 1

The correct option is C $pH<7.0$

Cathode reaction:
$C{u}^{2+}+2e^{-}\to Cu\left(s\right)$
Anode reaction:
$4O{H}^{-}\to 2H_{2}O+O_2+4e^{-}$
It can be seen that $O{H}^{-}$ ions from the solution are converted to $O_2$ which left out the solution acidic. Thus the $pH$ of the solution decreases during the electrolysis.

Hence, option C is correct.