Precipitation Equilibria (Ksp)
The equilibrium constant governing precipitates is called Ksp. This is for the reaction
Solid ? cation+(aq) +anion-(aq)
For example, for silver chloride, we have
AgC?(s) ? Ag+(aq) + C? -(aq)
And Ksp(AgC?)) = [Ag+][C? -]