Question

Predict the products of electrolysis in each of the following:
(i) An aqueous solution of $AgN{O}_3$ with silver electrodes.
(ii) An aqueous solution of $AgN{O}_3$ with platinum electrodes.
(iii) A dilute solution of $H_{2}S{O}_4$ with platinum electrodes.
(iv) An aqueous solution of $CuC{l}_2$ with platinum electrodes

Answer 1

(i) An aqueous solution of $AgN{O}_3$ with silver electrodes.

At cathode: Silver ions have lower discharge potential than hydrogen ions. Hence, silver ions will be deposited in preference to hydrogen ions.

At anode: Silver anode will dissolve to form silver ions in the solution.
$Ag\to A{g}^{+}+e^{-}$

(ii) An aqueous solution of $AgN{O}_3$ with platinum electrodes.

At cathode: Silver ions have lower discharge potential than hydrogen ions. Hence, silver ions will be deposited in preference to hydrogen ions.

At anode: Hydroxide ions having lower discharge potential will be discharged in preference to nitrate ions. Hydroxide ions will decompose to give oxygen.
$4O{H}^{-}\left(aq\right)\to 2H_{2}O\left(l\right)+O_2\left(g\right)+4e^{-}$

(iii) A dilute solution of $H_{2}S{O}_4$ with platinum electrodes.

At cathode: $2H^{+}+2e^{-}\to H_2\left(g\right)$

At anode: Hydroxide ions having lower discharge potential will be discharged in preference to sulphate ions. Hydroxide ions will decompose to give oxygen.
$4O{H}^{-}\left(aq\right)\to 2H_{2}O\left(l\right)+O_2\left(g\right)+4e^{-}$

(iv) An aqueous solution of $CuC{l}_2$ with platinum electrodes

At cathode: Cupric ions will be reduced in preference to protons
$C{u}^{2+}+2e^{-}\to Cu$

At anode: Chloride ions will be oxidized in preference to hydroxide ions
$2C{l}^{-}\to C{l}_2+2e^{-}$