Kohlrausch Law

Kohlrausch law

[′kōl‚rau̇sh ‚lȯ]
(physical chemistry)
The law that every ion contributes a definite amount to the equivalent conductance of an electrolyte in the limit of infinite dilution, regardless of the presence of other ions.
The law that the equivalent conductance of a very dilute solution of a strong electrolyte is a linear function of the concentration.

Kohlrausch Law

 

the law of the additivity of electric conductances at infinite dilution of solutions of electrolytes. It was established by F. Kohlrausch in 1879 on the basis of experimental data; the law was later explained on the basis of the theory of electrolytic dissociation. It expresses the independence of the motions of ions at infinite dilution. The equivalent conductance of a solution under these conditions can be regarded as the sum of the equivalent conductances of the cations and the anions, which are also termed the ion mobilities at infinite dilution. The mobilities are proportional to the absolute velocity of the motion of the ions and depend on temperature and the type of solvent. With an increase in the solution’s concentration, the Kohlrausch law becomes inapplicable because of the increase in the interactions between ions as well as other reasons.

V. A. KIREEV