A sparingly soluble salt having general formula and molar solubility S is in equilibrium with its saturated solution. Derive a relationship between the solubility and solubility product for such salt.
In order to derive the relationship between the solubility and solubility product for such a salt we will take the following steps,
We will assume the solubility to be S.
Initially, we will assume that 1 mole of AxBy was present. Out of it, S moles were dissolved in order to give xS and yS moles of Ap+ and Bq- respectively. We can understand it better through the following equation: -
At t=0, 1 0 0
At Equilibrium,
We know that, solubility product
=
=