Conductance Of Electrolytic Solutions

The molar conductivity of a weak electrolyte typically decreases sharply with an increase in concentration. This behavior can be explained using the following reasoning:

1. Definition of Molar Conductivity: Molar conductivity (Λ_m) is defined as the conductivity of a solution divided by the molar concentration of the electrolyte. It is expressed as:
Λ_m = κ/C
where κ is the conductivity and C is the concentration of the electrolyte.

2. Weak Electrolytes and Ionization: Weak electrolytes only partially ionize in solution. With higher concentrations, the degree of ionization decreases because the ions are closer together and experience more interaction, leading to reduced mobility of ions.

3. Concentration and Ion-Interaction: At higher concentrations, ion-ion interactions increase, leading to electrostatic forces that hinder the movement of ions. Therefore, fewer ions contribute to conductivity, reducing the molar conductivity.

4. Limit at Infinite Dilution: At infinite dilution, the ions are farthest apart, and their interaction is minimized, allowing for maximum mobility and thus the highest possible value of molar conductivity for the electrolyte.

In summary, as the concentration of a weak electrolyte increases, the molar conductivity decreases sharply due to enhanced ion interactions and reduced ion mobility.