When two aqueous solutions react, they sometimes form solids in the solution. The solid is called a precipitate. Precipitation reactions occur when the cations of one reactant and the anions of a second reactant found in aqueous solutions combine to form an insoluble ionic solid that we call a precipitate.
How do you know if a precipitate will form?
If the value of the ion product is greater than the value of the Ksp, then a precipitate will form. The formation of the precipitate lowers the concentration of each of the ions until the ion product is exactly equal to the Ksp, at which point precipitation ceases.
Where is a precipitate formed?
Formation of an insoluble compound will sometimes occur when a solution containing a particular cation (a positively charged ion) is mixed with another solution containing a particular anion (a negatively charged ion). The solid that separates is called a precipitate.