Question

How does molar conductance of a strong electrolyte vary with its concentration in solution?

Describe the characteristics of variation of conductance with dilution for a strong electrolyte. How would you explain them qualitatively?

Answer 1

1. The molar conductivity of a strong electrolyte (such as KCl or HCl) decreases slowly with an increase in concentration.
2. At low concentrations, the molar conductivity varies linearly with the square root of concentration, but at higher concentrations, the variation becomes non-linear.
3. As the concentration decreases (or as dilution increases), molar conductivity increases and approaches a limiting value known as the limiting molar conductivity (denoted as \[\ce{\Lambda^0_m}\]).
4. This behaviour is illustrated by extrapolating the Λₘ versus \[\sqrt{c}\] graph to \[\sqrt{c}\] = 0, where \[\ce{\Lambda^0_m}\] is obtained.