Question

The Kohlrausch's law is related to:

• A. Molar conductance of ions of electrolyte at infinite dilution
• B. Independent migration of ions at infinite dilution
• C. Conductance of ions of electrolyte at higher concentration
• D. Dependent migration of ions of electrolyte at infinite dilution

Answer 1

Answer: (A), (B)

Independent migration of ions at infinite dilution

Kohlrausch law:
At infinite dilution, when all the interionic effects disappear and dissociation of electrolyte is complete, each ion makes a definite contribution towards equivalent conductance/molar conductance of the electrolyte irrespective of the nature of the ion with which it is associated.

At infinite dilution, the ion becomes totally independent of other ions. At this point, it contributes maximum towards the conductance of the solution. This value of molar conductance is known as limiting molar conductivity. It is also called as molar conductivity at infinite dilution. It is represented by ${\Lambda }_m^0$

Kohlrausch law of independent migration of ions:
${\Lambda }_m^0={\lambda }_{+}^0+{\lambda }_{-}^0$

${\lambda }_{+}^0\to \text{Limiting molar conductivity of cation}$
${\lambda }_{-}^0\to \text{Limiting molar conductivity of anion}$