Question

Depict the galvanic cell in which the reaction Zn(s) + 2Ag⁺(aq) → Zn²⁺(aq) + 2Ag(s) takes place, further show:

(i) which of the electrode is negatively charged,

(ii) the carriers of the current in the cell, and

(iii) individual reaction at each electrode.

Answer 1

The galvanic cell corresponding to the given redox reaction can be represented as:

(i) Zn electrode is negatively charged because at this electrode, Zn oxidizes to Zn²⁺ and the leaving electrons accumulate on this electrode.

(ii) Ions are the carriers of current in the cell.

(iii) The reaction taking place at Zn electrode can be represented as:

And the reaction taking place at Ag electrode can be represented as:

.

(iv) In aqueous solutions, CuCl₂ ionizes to give Cu²⁺ and Cl^– ions as:

On electrolysis, either of Cu²⁺ ions or H₂O molecules can get reduced at the cathode. But the reduction potential of Cu²⁺ is more than that of H₂O molecules.

Hence, Cu²⁺ ions are reduced at the cathode and get deposited.

Similarly, at the anode, either of Cl^– or H₂O is oxidized. The oxidation potential of H₂O is higher than that of Cl^–.

But oxidation of H₂O molecules occurs at a lower electrode potential than that of Cl^– ions because of over-voltage (extra voltage required to liberate gas). As a result, Cl^– ions are oxidized at the anode to liberate Cl₂ gas.