What is Kohlrausch’s law of independent migration of ions? Write its
mathematical expression. What is the practical use of this law?
Answers
ANSWER
Kohlrausch law of independent migration of ions:
The law states that at infinite dilution, each ion migrates independently of its co-ion and make its own contribution to the total molar conductivity of an electrolyte irrespective of the nature of other ion with which it is associated.
The molar conductivity of the electrolyte at zero concentration is equal to the sum of molar conductivity of cation and the molar conductivity of anion at infinite dilution.
Λ
0
=λ
+
0
+λ
−
0
Application:
The law is used to calculate the molar conductivity of any electrolyte at zero concentration. For example, the molar conductivity of acetic acid at zero concentration can be calculated from the following expression.
Λ
0
(CH
3
COOH)=Λ
0
(HCl)+Λ
0
(CH
3
COONa)−Λ
0
(NaCl)