what is Kohlrausch's law?
Answers
Kohlrausch's law states that the equivalent conductivity of an electrolyte at infinite dilution is equal to the sum of the conductances of the anions and cations. If a salt is dissolved in water, the conductivity of the solution is the sum of the conductances of the anions and cations.
F .W. Kohlraush (1875) determined the values of equivalent conductivity at infinite dilution for a large number of electrolytes and observed that the difference between the equivalent conductivity at infinite dilution of pairs of salts, having either a cation or anion in common, is constant at constant temperature.
For example, the difference between at 25°C for K and Na salts having a common anion is always found to be and that for chloride and bromide having a common cation is always . It is clear from the following table
Applications:
(i) In calculating the equivalent conductivity at infinite dilution of weak electrolyte.
(ii) In explaining the independent motion of ions assumed in Arrhenius theory.
(iii) In calculating the absolute velocity of ion.
(iv) In calculating the ionic product of water.
(v) In determining the degree of dissociation of electrolytes.
(vi) In finding out the solubility of sparingly soluble salts.