Potassium nitrate is a white to dirty gray crystalline solid. Water soluble. Noncombustible, but accelerates the burning of combustible materials. If large quantities are involved in fire or the combustible material is finely divided an explosion may result. May explode under prolonged exposure to heat or fire. Toxic oxides of nitrogen are produced in fires. Used in solid propellants, explosives, fertilizers. Potassium nitrate has a chemical formula of KNO3. It is an ionic salt of potassium ions K+ and nitrate ions NO3-, and is therefore an alkali metal nitrate. It is a natural source of nitrate and has been used as a constituent for several different purposes, including food preservatives, fertilizers, tree stump removal, rocket propellants and fireworks. Potassium nitrate is a common active ingredient in dentrifices where it exerts an antisensitivity action. It provides increasing protection against painful sensitivity of the teeth to cold, heat, acids, sweets or contact.