Question

The molar conductivity at infinite dilution of a strong electrolyte can be obtained by extrapolating the curve Λ_m vs `sqrt c`, but the same cannot be done for a weak electrolyte. Explain why.

Answer 1

For a strong electrolyte, the Λ_m vs `sqrt c` plot is a straight line, so `Lambda_m^circ` can be obtained by extrapolation.

But for a weak electrolyte, the Λ_m vs `sqrt c` curve is highly curved due to partial ionisation and significant increase in degree of dissociation on dilution. Hence, `Lambda_m^circ` cannot be obtained by extrapolation.

Instead, it is calculated using Kohlrausch’s law of independent migration of ions.