Question

(a) The cell reactìon in Daniell cell is Zn_(s) + CU²⁺_(aq) → Zn²⁺_(aq) + CU_(s) and Nernst equation for single electrode potential for general electrode reaction 

Mⁿ⁺_(aq) + ne⁻⟶M_(s) is

E_Mⁿ+M = E⁰_Mⁿ⁺_/M - \(\frac{2.303RT}{nF} log \frac{[M]}{[M^{n+}]}\)

Derive Nernst equation for Daniell cell.

(b) Daniell cell is a primary cell while lead storage cell is a secondary cell. Write any one difference between primary cells and secondary cells.

Answer 1

(a) In Daniell cell, the electrode potential for any given concentration of Cu²⁺ and Zn²⁺ ions, we can write, For Cathode:

(b) In primary cells the reaction occurs only once and after use over a period of time cell becomes dead and cannot be reused again. Here the cell reaction is irreversible. e.g., dry cell Secondary cells after use can be recharged by passing current through them in the opposite direction so that they can be used again. Here the cell reaction is reversible. e.g., Lead storage cell.