State Kohlrausch’s law of independent migration of ions. Why does the conductivity of a solution decreases with dilution?

Ans:

Kohlrausch’s law of independent migration of ions states that the limiting molar conductivity of an electrolyte can be expressed as the sum of the individual contributions of the anion and the cation of the electrolyte, e.g.

$ \lambda ^o_{m(CH_3COOH)}= \lambda^o _{CH_3COO^-} \, + \, \lambda ^o _{H^+}$

The conductivity of a solution is related with the number of ions present per unit volume of the solution. When the solution is diluted, the number of - ions per unit volume decreases. Hence, conductivity or specific conductance of the solution decreases.