solubility product

solubility product Symbol K_s. The product of the concentrations of ions in a saturated solution. For instance, if a compound A_xB_y is in equilibrium with its solution A_xB_y(s) ↔ xA⁺(aq) + yB^–(aq)

the equilibrium constant is K_c = [A⁺]^x[B^–]^y/[A_xB_y]

Since the concentration of the undissolved solid can be put equal to 1, the solubility product is given by K_s = [A⁺]^x[B^–]^y

The expression is only true for sparingly soluble salts. If the product of ionic concentrations in a solution exceeds the solubility product, then precipitation occurs.