in general, when will a sparingly soluble salt precipitate from solution? Solution A sparingly soluble salt will precipitate when the ion product exceeds Ksp. The solubility product constant, Ksp, is the equilibrium constant for a solid substance dissolving in an aqueous solution. It represents the level at which a solute dissolves in solution. The more soluble a substance is, the higher the Ksp value it has. BaSO4 Ksp = [Ba 2+ ] [SO4 2- ] A low Ksp indicates a low solubility because the values of these concentrations (only this amount of the compound will be in the form of ions and the rest will form precipitate) will be low. As soon as the concentration of the ions in the solution exceeds the Ksp value a precipitate will appear. .