Sodium hydroxide, commonly known as Naoh, caustic soda, Caustic Soda, caustic soda, is a strong caustic soda, generally in the form of sheets or granules, soluble in water when exothermic and forming an alkaline solution, and deliquescence Easy to absorb water vapor in the air deliquescence and carbon dioxide metamorphism. Naoh is one of the necessary chemicals in Chemical Laboratory, and it is also one of the common chemicals. The pure product is a colorless and transparent crystal. Density 2.130 G / cm. Melting point 318.4 °C. Boiling Point 1390 °C. Industrial products contain small amounts of sodium chloride and sodium carbonate and are white opaque crystals. There are blocky, flaky, grainy and rod-shaped, etc. . Formula 40.01 sodium hydroxide is used as an alkaline cleaning agent in water treatment and is soluble in ethanol and glycerol; insoluble in propanol and ether. It also corrodes sodium and carbon at high temperatures. Disproportionation reaction with chlorine, bromine, iodine and other halides. Neutralize acids to produce salt and water.