Law of dilution

is the limiting value of molar conductivity extrapolated to zero concentration or infinite dilution, this results in the following relation: Consider a binary electrolyte AB which dissociates reversibly into A+ and B− ions.

Ostwald noted that the law of mass action can be applied to such systems as dissociating electrolytes.

The equilibrium state is represented by the equation: If α is the fraction of dissociated electrolyte, then αc0 is the concentration of each ionic species.

The Ostwald law of dilution provides a satisfactory description of the concentration dependence of the conductivity of weak electrolytes like CH3COOH and NH4OH.

[3] [4] The variation of molar conductivity is essentially due to the incomplete dissociation of weak electrolytes into ions.

The decrease in molar conductivity as a function of concentration is actually due to attraction between ions of opposite charge as expressed in the Debye-Hückel-Onsager equation and later revisions.