State Kohlrausch law of independent migration of ions. Write its application.
Answers
KOHLRAUSCH’S LAW :
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.
APPLICATION :
1.) Kohlrausch law helps us in the determination of limiting molar conductivities for any electrolyte. Weak electrolytes have lower molar conductivities and lower degree of dissociation at higher concentrations. The graph plotted between molar conductivity and c1/2 (where c is the concentration) is not a straight line for weak electrolytes. The molar conductivity of weak electrolyte increases steeply at lower concentrations. Therefore, limiting molar conductivity, Ëm° cannot be obtained by extrapolation of molar conductivity to zero concentration. Hence, we use the Kohlrausch law of independent migration of ions for the determination of limiting molar conductivity, Ëm° for weak electrolytes.
2.) Kohlrausch law also helps us in determining the value of dissociation constant from the value of molar conductivity and limiting molar conductivity for a weak electrolyte at a given concentration.
α = ΛËm∘
Where, α = dissociation constant
Λ = molar conductivity
Ëm° = limiting molar conductivity
Answer:
Kohlrausch law of infinite dilution
Explanation:
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.
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.