Question

How does the molar conductivity for the solution of a strong electrolyte vary with concentration? Explain graphically.

How can molar conductivity at infinite dilution be obtained for a strong electrolyte?

Answer 1

A strong electrolyte, such as KCl, HCl, etc., has a gradual drop in molar conductivity as concentration rises. The molar conductivity has been observed to vary linearly with the square root of concentration at low concentrations.

However, as the graph in the figure makes evident, the fluctuation is not linear at larger doses. The square root of concentration is displayed versus the molar conductance of KCl in the figure. The curve is nearly straight when the concentration is low (i.e., the dilution is high), indicating a linear relationship between molar conductivity and the square root of concentration. The curve no longer follows a straight line as the concentration rises.

The graph in the figure makes it evident that the molar conductivity of a strong electrolyte solution approaches a limiting value when the concentration of the solution falls (i.e., the dilution of the solution grows).

For a strong electrolyte, the following equation is discovered to govern the change in molar conductivity with concentration.

`Lambda_m = Lambda_m^infty - b sqrt c`    ...(i)

where Λ_m = Molar conductivity at a particular concentration, c

`Lambda_m^infty` = Molar conductivity at infinite dilution (i.e., when c → 0)

c = Concentration of solution

and b = Constant.