Question

Define kohlrausch's law and discuss its important application

Answer 1

Kohlrausch's Law states that Limiting molar conductivity or conductivity at infinite dilution is equal to sum  of conductances of anions and cations raised to the power their stoichiometric coefficient. It is used for calculating limiting molar conductivity of weak electrolytes. 

Answer 2

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
i) Determination of for weak electrolytes : The molar conductivity of a weak electrolyte at infinite dilution cannot be determined by extrapolation method. However, values for weak electrolytes can be determined by using the Kohlrausch's equation.

ii) Determination of the degree of ionisation of a weak electrolyte: The Kohlrausch's law can be used for determining the degree of ionisation of a weak electrolyte at any concentration. If is the molar conductivity of a weak electrolyte at any concentration C and, is the molar conductivity of a electrolyte at infinite dilution. Then, the degree of ionisation is given by,
Thus, knowing the value of , and (From the Kohlrausch's equation), the degree of ionisation at any concentration can be determined.
Hope this helps u!!