Solubility and Solubility Product of Sparingly Soluble Salt:

A conductivity of a saturated solution of a sparingly soluble salt could be determined by subtracting the measured conductivity of the pure solvent from the measured conductivity of the saturated solution that is.

κ_salt = κ _solution-  κ _solvent                                                       

As per Eq. (4.8) of Unit 4, the molar conductivity of the salt in saturated solution is given by

Λ_salt  = κ _salt  / c

where c is the concentration. Since the salt is sparingly soluble, its solution can be considered to be infinitely dilute and we can replace molar conductivity with limited molar conductivity of the salt. Which are,

Λ_salt = Λ ^∝_salt = Λ ₊^∝   +Λ _-^∝

Thus,

c = κ _salt / Λ ₊^∝ +Λ _-^∝