Question

Which of the following statements are correct regarding the electrolysis of silver chloride solution using inert electrodes?
i) ${\mathrm{Ag}}^{+}$ and $H^{+}$ ions would migrate towards the cathode.
ii) ${\mathrm{Cl}}^{-}$ and ${\mathrm{OH}}^{-}$ ions would migrate towards the anode.
iii) Reaction at the cathode: $2H^{+}\left(\mathrm{aq}\right)+2e^{–}⟶H_2\left(g\right)$
iv) Reaction at the anode: $2{\mathrm{OH}}^{–}\left(\mathrm{aq}\right)–2e^{–}⟶H_{2}O\left(l\right)+\frac{1}{2}{O}_2\left(g\right)$

• A. i, ii, iii
• B. i and ii
• C. i, ii, and iv
• D. i, ii, iii, and iv

Answer 1

The correct option is C i, ii, and iv

• When an aqueous solution of silver chloride is electrolysed, the ions formed are ${\mathrm{Ag}}^{+}$, $H^{+}$, ${\mathrm{OH}}^{-}$ and ${\mathrm{Cl}}^{-}$.
• Both ${\mathrm{Ag}}^{+}$ and $H^{+}$ ions migrate towards the cathode but ${\mathrm{Ag}}^{+}$ ion is reduced at the cathode since it has a higher preference for reduction according to the electrochemical series.
• Both the ${\mathrm{OH}}^{-}$ and ${\mathrm{Cl}}^{-}$ ions would migrate towards the anode. But ${\mathrm{OH}}^{-}$ ion will be oxidised at the anode since it has a higher preference for oxidation according to the electrochemical series.

So, the reactions that would be taking place at the electrodes are:
At cathode: $2{\mathrm{Ag}}^{+}\left(\mathrm{aq}\right)+2e^{–}⟶2\mathrm{Ag}\left(s\right)$
At anode: $2{\mathrm{OH}}^{–}\left(\mathrm{aq}\right)–2e^{–}⟶H_{2}O\left(l\right)+\frac{1}{2}{O}_2\left(g\right)$