Predict the products of electrolysis of the following. An aqueous solution of ${AgNO}_{3}$ with silver electrodes.

Moderate

A

Ag from anode dissolves, while ${Ag}^{+}$ ions get reduced and deposited at cathode
B

Ag from cathode dissolves, while ${Ag}^{+}$ ions get reduced and deposited at anode
C

${Ag}^{+}$ from anode dissolves while Ag get reduced and deposited at cathode.
D

${Ag}^{+}$ from cathode dissolves while ${Ag}^{+}$ ions get oxidized and deposited at anode.

Solution

An aqueous solution of ${AgNO}_{3}$ with silver electrode, when undergoes electrolysis, two oxidation and two reduction half-reactions must be considered.
Oxidation (at anode)
$(A) Ag (s) ⟶ {Ag}^{+} (aq) + e^{-}; E ° = - 0.80 V$
$(B) 2 H_{2} O (l) ⟶ O_{2} (g) + 4 H^{+} (aq) + 4 e^{-}; E ° = - 1.23 V$
Reduction (at cathode)
$(C) {Ag}^{+} (aq) + e^{-} ⟶ Ag (s); E ° = + 0.80 V$
$(D) 2 H_{2} O (l) + 2 e^{-} ⟶ H_{2} (g) + 2 {OH}^{-} (aq); E ° = - 0.83 V$
By E° values of (A ) and (B ) it appears that at anode silver of silver anode gets oxidized more readily because oxidation potential of Ag is greater than that of $H_{2} O$ molecule. Similarly by E° values of (C) and (D), it appears that at cathode reduction potential of ${Ag}^{+}$ ions is higher than that of $H_{2} O$ molecules.
Therefore, on electrolysis of aq. ${AgNO}_{3}$ solution with silver electrodes, Ag from silver anode dissolves while ${Ag}^{+}$ (aq) ions present in the solution get reduced and deposited at cathode.

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