Question

When an aqueous solution of sodium chloride is electrolysed using platinum electrodes, the ions discharged at the electrodes are:

• A. sodium and hydrogen
• B. sodium and chloride
• C. hydrogen and chloride
• D. hydroxyl and chloride

Answer 1

Answer: (C)

hydrogen and chloride

Electrolysis of aqueous $NaCl$:-

$NaCl\rightleftharpoons N{a}_{\left(aq\right)}^{+}+C{l}_{\left(aq\right)}^{-}$

$H_2{O}_{\left(l\right)}\rightleftharpoons H_{\left(aq\right)}^{+}+O{H}_{\left(aq\right)}^{-}$

$\to$ At Cathode:-

Hydrogen reduction takes place in preference to $N{a}^{+}$ as a reduction potential of $N{a}^{+}$ is less than Hydrogen.

$\therefore 2H^{+}+2e^{-}\rightleftharpoons H_{2\left(g\right)}$---------reduction.

$\to$ At Anode:-

Chlorine gas gets oxidized at the anode in preference to $O{H}^{-}$

$\therefore 2C{l}^{-}\rightleftharpoons C{l}_{2\left(g\right)}+2e^{-}$.

hydrogen and chloride discharged at the cathode and anode, respectively.

Option $C$ is correct.