Viscosity of the medium:

The dependence of conductance on viscosity of the medium is given by Walden's rule, according to which the equivalent conductance of an electrolyte is inversely proportional to the viscosity of the medium, that is.

Λ ∞ η0 = constant

where Λ0 is the equivalent conductance at infinite dilution and ηo is coefficient of viscosity of the solvent. If ions are not solvated, i.e., which have the similar size within all the solvents, after that it follows from Walden rule which Λ ^∞ η0 should be constant and independent of the nature of the solvent. This is true only for ions like tetra-alkyl ammonium cations, that are not solvated. Ions while extensive solvation occurs, effective radii of the ions will not be constant and Walden rule will not be obeyed.