The chemical formula is NaOH, commonly known as caustic soda, pyrotechnic soda, caustic sodium, is a strong alkali with strong corrosion, generally flake or block form, easily soluble in water (heat dissipation when dissolved in water) and forms alkaline solution, and deliquescence, easy to absorb water vapor (deliquescence) and carbon dioxide (deterioration) in the air, can be added** to check whether it deteriorates