Kohlrausch law is useful in calculating ­\(\Lambda ^0\) for any electrolyte from the ­\(\lambda ^0\) of individual ions. The molar conductivities of H⁺ and OH⁻ ions are very high because these ions are passed from one molecule to another and released at the electrodes without travelling. Equivalent conductance of weak electrolytes can be calculated from the conductances of completely dissociated strong electrolytes e.g.,

\(\Lambda^0_{CH_3COOH} = \Lambda^0_{CH_3COONa} + \Lambda^0_{HCl} - \Lambda^0{NaCl}\)

Or,\(\Lambda^0_{CH_3COOH} = \Lambda^0_{Na^+} + \Lambda^0_{CH_3COO^-} + \Lambda^0_{H^+} + \Lambda^0_{Cl^-} - \Lambda^0_{Na^+} - \Lambda^0_{Cl^-}\)

Or,\(\Lambda^0_{CH_3COOH} = \Lambda^0_{CH_3COO^-} + \Lambda^0_{H^+} \)

Solubility of sparingly soluble salts can be calculated from the specific conductance of its saturated solution and from the equivalent conductivity at infinite dilution obtained from ­ ­

\[\Lambda ^0_e = \frac{1000 K_{salt}}{C}\]

\[\text{Absolute ionic mobility =} \frac{\text{Ionic conductance}}{96500} \]

\[\text{Absolute ionic mobility =} \frac{\Lambda _0}{96500} \]

Using ionic conductance measurements, the ionic product of water can be determined as 1 × 10⁻¹⁴ at 25°C.

Variation of equivalent conductance with a concentration of the strong electrolyte is given by

\(\lambda_M = \lambda ^{\infty} – b\sqrt{c}\)

The correct answer is option 1. \(\lambda_M = \lambda ^{\infty} – b\sqrt{c}\)

In this expression:

\(\lambda_M\) represents the molar conductivity of the strong electrolyte at a specific concentration 'c.'
\(\lambda^{\infty}\) represents the limiting molar conductivity of the strong electrolyte at infinite dilution.
'b' is a constant that takes into account the contribution of solvent molecules to the overall conductance.
'c' is the concentration of the strong electrolyte in the solution.

The expression shows how the molar conductivity (\(\lambda_M\)) of a strong electrolyte varies with its concentration (\(c\)). As the concentration increases, the molar conductivity (\(\lambda_M\)) approaches its limiting value (\(\lambda^{\infty}\)) and is influenced by the term \(- b\sqrt{c}\). This term accounts for the effect of ion-ion interactions and solvation effects on the overall conductance at finite concentrations.