You can predict whether a precipitation reaction will occur upon mixing two aqueous solutions by referring to a table of solubility rules. If at least one of the potential products is insoluble, then a precipitation reaction will occur.
Work Step by Step
If any precipitate forms as the result of a reaction, it's a precipitation reaction. Some compounds may only be soluble in extremely high volumes of solute or at higher temperatures; These reactions are still precipitate-forming under most conditions and can be considered precipitation reactions in those cases.