Question

Predict the product of electrolysis in the following:

An aqueous solution of AgNO₃ with silver electrodes.

Answer 1

AgNO₃ ionizes in aqueous solutions to form Ag⁺ and `"NO"_3^(-)` 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.

\[\ce{Ag+_{ (aq)} + e- -> Ag_{(s)}};\] E° = + 0.80 V

\[\ce{2H_2O_{(l)} + 2e- -> H_{2(g)} + 2OH^-_{ (aq)}}\]; E° = - 0.83 V

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.

\[\ce{Ag_{(s)} -> Ag+_{(aq)} + e-}\];  E° = - 0.80 V

\[\ce{2H_2O_{(l)} -> O_{2(g)} + 4H+_{ (aq)} + 4e-}\]; E° = -1.23 V

Therefore, Ag metal gets oxidized at the anode.