Describe how to write the Ksp.

Well, for a start Ksp=Ksolubility product, and we use an equilibrium expression.

Explanation:

For the sparingly soluble salt, MX, we write the equation that represents its dissolution:

MX (s) H2O⇌M++X-

Ksp=[M+][X-][MX (s) ], but MX (s) as A SOLID cannot express a concentration, and thus the expression simplifies to ...

Ksp=[M+][X-]

Usually standard conditions are specified, because a hot solution can generally hold more solute than a cold one.

For salts of the form MX2, Ksp=[M2+][X-]2. Ksp

have been measured for a host of insoluble, and semi-soluble ionic salts.