The physicochemical properties is tasted for colorless transparent crystal, the relative density of 2.130. Melting point 318.4 ℃. Boiling point 1390 ℃. The sold a solid caustic soda and liquid two: pure solid caustic soda were white, and a piece of outfit, flake, stick, granular, very brittle; Pure liquid caustic soda for colorless transparent liquid. Solid caustic soda has very strong suction wet sex. Soluble in water, dissolve the exothermic, in alkaline solution, satiny sense; Soluble in ethanol and glycerin; Insoluble in acetone, ethyl ether. Corrosive extremely strong, the fiber, skin, glass, ceramics, etc have corrosion function. Aluminum and zinc, and nonmetal boron and silicon emit hydrogen reaction; And chloride, bromine, iodine, etc QiHua halogen happen response; And acid up and neutralizing action and the generated salt and water.