Question

Define limiting molar conductivity.

Hint:

At infinite dilution: Interionic forces → Zero Conductivity → Maximum \(\Lambda_m^\circ = \lambda_+^\circ + \lambda_-^\circ\)

Answer 1

Concept: Molar conductivity (\( \Lambda_m \)) increases with dilution because interionic interactions decrease. At infinite dilution, ions move independently and conductivity reaches its maximum value.
Definition:
Limiting molar conductivity (\( \Lambda_m^\circ \)) is defined as the molar conductivity of an electrolyte at infinite dilution, where each ion contributes independently to the total conductivity. Mathematically: \[ \Lambda_m^\circ = \lambda_+^\circ + \lambda_-^\circ \] where:

• \( \lambda_+^\circ \) = limiting molar conductivity of cation
• \( \lambda_-^\circ \) = limiting molar conductivity of anion

Explanation: At infinite dilution:

• Interionic attraction becomes negligible.
• Ions attain maximum mobility.
• Conductivity depends only on individual ionic contributions.

\[ \therefore \Lambda_m^\circ \text{ represents maximum molar conductivity of an electrolyte. \]