Question

A NiCd battery uses nickel and cadmium to produce a potential difference. Using these equations, answer the following questions. I. 2NiO(OH) (s) + 2H 2O (l) + 2 e - → 2Ni(OH) 2 (s) + 2 OH¯ (aq) II. Cd (s) + 2OH¯ (aq) → Cd(OH) 2 (s) + 2e¯ III. Cd (s) + 2NiO(OH) (s) + 2 H 2O (l) → 2 Ni(OH) 2 (s) + Cd(OH) 2 (s) Which equation represents the whole chemical reaction within the galvanic cell? I II III I and II

Answer 1

Answer : The correct chemical reaction within the galvanic cell is,

(3)
`Cd(s)+2NiO(OH)(s)+2H_2O(l)\rightarrow 2Ni(OH)_2(s)+Cd(OH)_2(s)`

Explanation :

Galvanic cell : It is defined as a device which is used for the conversion of the chemical energy produces in a redox reaction into the electrical energy. It is also known as the electrochemical cell.

The redox reaction occurs between the nickel and cadmium.

In the galvanic cell, the oxidation occurs at an anode which is a negative electrode and the reduction occurs at the cathode which is a positive electrode.

The balanced two-half reactions will be,

Oxidation half reaction :
`Cd(s)+2OH^-(aq)\rightarrow Cd(OH)_2(aq)+2e^-`

Reduction half reaction :
`NiO(OH)(aq)+H_2O(l)+e^-\rightarrow Ni(OH)_2(aq)+OH^-(aq)`

Thus the overall reaction will be,

`Cd(s)+2NiO(OH)(s)+2H_2O(l)\rightarrow 2Ni(OH)_2(s)+Cd(OH)_2(s)`