Solubility Product Constant (Ksp)

The solubility product constant (Ksp) is a number that measures how much of a chemical compound can dissolve in water until it reaches equilibrium. For a sparingly soluble salt, like calcium carbonate, Ksp indicates the maximum product of the concentrations of its dissolved ions (e.g., calcium and carbonate) that can exist together in solution without forming more solid. When the ion concentrations multiply to a value equal to Ksp, the solution is saturated. If they exceed this, excess solid will form. Ksp helps chemists understand and predict the solubility of compounds under different conditions.