Calcium hydroxide, also known as slaked lime, is a chemical compound with the chemical formula Ca(OH)2. It is a colourless crystal or white powder, and is obtained when calcium oxide (called lime or quicklime) is mixed, or "slaked" with water. It can also be precipitated by mixing an aqueous solution of calcium chloride and an aqueous solution of sodium hydroxide. A traditional name for calcium hydroxide is slaked lime, or hydrated lime. The name of the natural mineral is portlandite.
If heated to 512°C, calcium hydroxide decomposes into calcium oxide and water. A suspension of fine calcium hydroxide particles in water is called milk of lime. The solution is called lime water and is a medium strength base that reacts violently with acids and attacks many metals in presence of water. It turns milky if carbon dioxide is passed through, due to precipitation of calcium carbonate.
Because of its strong basic properties, calcium hydroxide has varied uses, such as
In Native American and Latin American cooking, calcium hydroxide is called "cal". Corn cooked with cal becomes nixtamal which significantly increases its nutrition value, and is also considered tastier and easier to digest.
In chewing Betel nut or coca leaves, calcium hydroxide is usually chewed alongside to keep the alkaloidstimulants chemically available for absorption by the body
In the petrochemical industry for manufacturing solid oil of various marks
In the manufacture of brake pads
In the manufacture of ebonite
For preparation of dry mixes for painting and decorating