A precipitate is a sparingly soluble solid that forms as a product when two solutions are mixed. It appears because the new combination of ions exceeds the solubility limit, so the solid separates out of solution. Precipitate formation is the basis of precipitation titrations and of many qualitative tests for ions.

沉淀是两种溶液混合时生成的难溶固体产物。它的出现是因为新组合的离子超过了溶解度极限,固体便从溶液中析出。沉淀的生成是沉淀滴定以及许多离子定性检验的基础。