Question

How does the molar conductivity of a weak electrolytic solution vary with concentration?

Why is it not possible to determine `Lambda_m^infty` for a weak electrolyte by the usual methods? Explain graphically.

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

How does the molar conductivity of a weak electrolyte vary with concentration? Explain graphically. Why is it not possible to determine `Lambda_m^infty` for a weak electrolyte graphically?

Answer 1

Weak electrolytes, such as CH₃COOH, NH₄OH, and HCN, dissociate less in solution than strong electrolytes. As a result, a weak electrolyte’s solution contains many fewer ions than a strong electrolyte of the same concentration. As a result, a weak electrolyte solution has significantly lower molar conductivity than a strong electrolyte.

The molar conductivity of a weak electrolyte grows gradually at lower concentrations before quickly increasing as the concentration of the solution is decreased (i.e., dilution is raised). As a result, a weak electrolyte’s molar conductivity does not change linearly with concentration. Figure displays the graph that plots the values of acetic acid’s molar conductivity (Λ_m) against the square root of its concentration`(sqrt c)`. It is evident from this graph that the curve is not a straight line, indicating that for a weak electrolyte, the change in molar conductivity with concentration is nonlinear.