Question

Predict the products of electrolysis in each of the folloiwng:
(i) An aqueous solution of AgNO3 with silver electrodes.(ii) An aqueous solution of AgNO3 with plantinum electrodes.(iii) A dilute solution of H2SO4 with platinum electrodes

Answer 1

 



Predict the products of electrolysis in each of the folloiwng:

(i) An aqueous solution of AgNO3 with silver electrodes.(ii) An aqueous solution of AgNO3 with plantinum electrodes.(iii) A dilute solution of H2SO4 with platinum electrodes

(i) AgNO3 ionizes in aqueous solutions to form Ag+ and  ions.

On electrolysis, either Ag+ ions or H2O molecules can be reduced at the cathode. But the reduction potential of Ag+ ions is higher than that of H2O.



Hence, Ag+ ions are reduced at the cathode. Similarly, Ag metal or H2O molecules can be oxidized at the anode. But the oxidation potential of Ag is higher than that of H2O molecules.



Therefore, Ag metal gets oxidized at the anode.

(ii) Pt cannot be oxidized easily. Hence, at the anode, oxidation of water occurs to liberate O2. At the cathode, Ag+ ions are reduced and get deposited.

(iii) H2SO4 ionizes in aqueous solutions to give H+ and ions.



On electrolysis, either of H+ ions or H2O molecules can get reduced at the cathode. But the reduction potential of H+ ions is higher than that of H2O molecules.



Hence, at the cathode, H+ ions are reduced to liberate H2 gas.

On the other hand, at the anode, either of ions or H2O molecules can get oxidized. But the oxidation of involves breaking of more bonds than that of H2O molecules. Hence, ions have a lower oxidation potential than H2O. Thus, H2O is oxidized at the anode to liberate O2molecules

Answer 2

Answer:

a) On electrolysis of aqueous solution of $AgNO_3$ with silver electrodes

$AgNO_3(aq)\rightarrow Ag{+}(aq)+NO_3^-(aq)$

$H_2O(l)\rightarrow H{+}(aq)+OH^-(aq)$

At cathode which is a negative terminal , cations will be reduced. At anode which is a positive terminal , anions will be oxidized.

The reaction with a higher value of Eº takes place at the cathode. Therefore, deposition of silver will take place at the cathode.

At cathode: $Ag^{+}+e^- \rightarrow Ag(s)$

At anode: $Ag\rightarrow Ag^++e^-$

Hence Ag will deposit at cathode and dissolve at anode

b) On electrolysis of aqueous solution of $AgNO_3$ with platinum electrodes

$AgNO_3(aq)\rightarrow Ag{+}(aq)+NO_3^-(aq)$

$H_2O(l)\rightarrow H{+}(aq)+OH^-(aq)$

At cathode which is a negative terminal , cations will be reduced. At anode which is a positive terminal , anions will be oxidized.

The reaction with a higher value of Eº takes place at the cathode. Therefore, deposition of silver will take place at the cathode.

At cathode: $Ag^{+}+e^- \rightarrow Ag(s)$

At anode: $4OH^-\rightarrow 2H_2O+O_2+4e^-$

Hence Ag will deposit at cathode and $O_2$ gas will generate at anode

c) A dilute solution of H2SO4 with platinum electrodes

$H_2SO_4(aq)\rightarrow H{+}(aq)+SO_4^{2-}(aq)$

$H_2O(l)\rightarrow H{+}(aq)+OH^-(aq)$

At cathode which is a negative terminal , cations will be reduced. At anode which is a positive terminal , anions will be oxidized.

The reaction with a higher value of Eº takes place at the cathode. Therefore, deposition of silver will take place at the cathode.

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

At anode: $4OH^-\rightarrow 2H_2O+O_2+4e^-$

Hence $H_2$ gas will generate at cathode and $O_2$ gas will generate at anode