Question

Why is it necessary to use salt bridge in a galvanic cell?

Hint:

For weak electrolytes, \(\alpha=\frac{\Lambda_m}{\Lambda_m^\circ}\). Salt bridge prevents charge build-up in half-cells.

Answer 1

Step 1: What is a salt bridge?
A salt bridge is a U-shaped tube filled with an inert electrolyte (e.g., $KCl$ in agar-agar) connecting the two half-cells of a galvanic cell.
Step 2: Functions of the salt bridge.
(i) It completes the electrical circuit by allowing ions to migrate between half-cells.
(ii) It maintains electrical neutrality: as ions are consumed at one electrode, ions from the bridge migrate to maintain charge balance. Without it, charge build-up would stop current flow.
Step 3: Conclusion.
\[ \boxed{\text{Salt bridge maintains electrical neutrality and sustains current flow in a galvanic cell.}} \]