<unk> , also known as lye and caustic soda, is an inorganic compound with the formula<unk> . It is a white solid ionic compound consisting of<unk>  cations and<unk>  anions .<unk>  is a highly caustic base and alkali that decomposes proteins at ordinary ambient temperatures and may cause severe chemical burns. It is highly soluble in water, and readily absorbs moisture and carbon dioxide from the air. It forms a series of hydrates . The monohydrate crystallizes from water solutions between 12.3 and 61.8 °C. The commercially available<unk> " is often this monohydrate, and published data may refer to it instead of the anhydrous compound. As one of the simplest<unk> s,<unk>  is frequently used alongside neutral water and acidic hydrochloric acid to demonstrate the pH scale to chemistry students.<unk>  is used in many industries: in the manufacture of pulp and paper, textiles, drinking water, soaps and detergents, and as a drain cleaner. Worldwide production in 2004 was approximately 60 million tons, while demand was 51 million tons.
Sodium hydroxide
Sodium hypochlorite
Amylmetacresol
Barium sulfate suspension
Silver nitrate
Chlorhexidine
Silver diammine fluoride
Perchloryl fluoride