Sodium hydroxide, chemical formula NaOH, commonly known as caustic soda, caustic soda, is a strong caustic alkali with strong corrosiveness, generally in sheet or block form, soluble in water (when dissolved in water exothermic) and form an alkaline solution, and also deliquescent, easy to absorb water vapor (deliquescence) and carbon dioxide (deterioration) in the air, can be added. Check for deterioration with hydrochloric acid.

NaOH is one of the necessary chemicals in chemical laboratories, and it is also one of the common chemical products. Pure products are colorless transparent crystals. The density is 2.130g/cm_. Melting point 318.4 C. Boiling point 1390 C. Industrial products contain a small amount of sodium chloride and sodium carbonate, which are white opaque crystals. They are massive, flaky, granular and rodlike. Formula 39.997.

Sodium hydroxide can be used as alkaline detergent in water treatment, soluble in ethanol and glycerol, insoluble in propanol and ether. Disproportionation reaction with halogens such as chlorine, bromine and iodine. It neutralizes with acids to form salt and water.