Precipitate

Name:
Precipitate
Detailed information:
(↓, ppt). Small particles that have settled out of a liquid or gaseous suspension by gravity, or that result from a chemical reaction. Precipitated compounds, such as blanc fixe (barium sulfate), are prepared in this way, for example, by the reaction BaCl₂ + Na₂SO₄ → NaCl + BaSO₄ . In formulas, a downward vertical arrow, ↓, or “ppt” is sometimes used to indicate a precipitate. A class of organic pigments called lakes are made by precipitating an organic dye onto an inorganic substrate. Colloidal particles dispersed in a gas, as flue dust in industrial stacks, can be precipitated by introducing an electric charge opposite to that which sustains the particlesSee Cottrell; Sedimentation.