NaOH

Sodium hydroxide, commonly abbreviated as NaOH and also known as caustic soda, is a strong base and alkali with the chemical formula NaOH. It appears as a white solid at room temperature and is highly hygroscopic, readily absorbing moisture from the air. In exposed conditions it can also absorb carbon dioxide and gradually form sodium carbonate on the surface.

NaOH is produced by the chlor-alkali process, in which an electrolytic cell converts a sodium chloride solution into sodium hydroxide, chlorine, and hydrogen. In water it dissociates to Na+ and OH-, giving a strongly alkaline solution with a pH near 14. The compound is highly soluble in water and releases a large amount of heat on dissolution.

Common uses include soap and detergent manufacture through saponification of fats and oils; pH control in water treatment and chemical manufacturing; the pulp and paper industry; alumina production; and various chemical syntheses, including biodiesel production. It is also used in drain cleaners and as a reagent in laboratories.

Safety considerations are important: NaOH is highly caustic and corrosive to skin, eyes, and mucous membranes. Inhalation of dust or mists can irritate the respiratory tract. It should be handled with appropriate personal protective equipment, stored in a sealed, dry container away from acids and moisture, and solutions should be added to water rather than water to concentrated base to limit the exothermic reaction.

Environmental notes: spills should be contained, neutralized, and disposed of according to local regulations. In the environment NaOH raises pH and can be harmful to aquatic life in concentrated forms.