Question

What is kohlrausch's law? how the degree of dissociation of weak electrolyte is calculated by this work?

Answer 1

Answer:

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.

The second class of compounds, known as weak electrolytes, are those where ionisation is incomplete. The ionisation will increase with dilution and hence the molar conductivity increases with dilution.Thus the conductivity is directly proportional to the degree of dissociation of electrolyte.

For weak electrolytes, the graph plotted between molar conductivity _/C [Under root C] (Where c is the concentration) is not a straight line. This is because weak electrolytes have lower molar conductivities and lower degree of dissociation at higher concentrations which increases steply at lower concentrations. Hence we use Kohlrausch law of independent migration of ions for determining to limit molar conductivity, Em° of weak electrolytes