Question

Why on dilution the Λ_m of CH₃COOH increases drastically, while that of CH₃COONa increases gradually?

Answer 1

In the case of CH₃COOH, which is a weak electrolyte, the number of ions increase on dilution due to an increase in degree of dissociation. 

CH₃COOH + H₂O CH₃COO— + H₃O⁺ 

In the case of strong electrolyte the number of ions remains the same but the interionic attraction decreases.