A sparingly soluble salt having general formula `A_xB_y` and molar solubility s is in equilibrium with its saturated solution. Derive a relationship between the solubility and solubility product for such salt.

Explanation

Suppose molar solubility of `A_(x)^(p+) B_(y)^(q-)` is S mol `L^(-1)`. Then
`{:(A_(x)^(p+)B_(y)^(q-) ,hArr,x A^(p+),+ ,yB^(q-),,),(,,x S,,y S,,):}`
`K_(sp) = [ A^(p+)]^(x) [B^(q-)]^(y)=[x S]^(x) [ y S ] ^(y)= x^(x) y^(y) S^(x+y)`