CaC2

Calcium carbide, with the chemical formula CaC2, is an inorganic compound that consists of calcium cations and acetylide (C2) anions. It is a dense, grayish-white solid that hydrolyzes readily in water to produce acetylene gas. Because of its reactivity with moisture, calcium carbide is stored in dry conditions and handled with care.

Production of calcium carbide occurs chiefly in electric arc furnaces from calcium oxide (lime) and coke at temperatures around 2000–2100°C. The typical simplified reaction is CaO + 3 C → CaC2 + CO. The process is energy intensive and produces carbon monoxide as a byproduct; the crude product is purified and then stabilized for transport and use.

A key property of CaC2 is its hydrolysis in water, which releases acetylene: CaC2 + 2 H2O → C2H2 + Ca(OH)2. This reaction is exothermic and gas evolution can be rapid, so handling requires dry conditions and appropriate ventilation. Acetylene itself is highly flammable and can form explosive mixtures with air, making storage and use safety-critical.

Industrial uses of calcium carbide are dominated by its role as a precursor to acetylene gas, which has long been employed for welding and cutting metal and as a versatile building-block chemical. Acetylene derived from CaC2 is also used in the synthesis of various organic chemicals, including vinyl chloride monomer and other derivatives. In addition to industrial chemistry, calcium carbide has historical uses in carbide lamps for lighting.

Safety measures emphasize keeping calcium carbide dry, avoiding contact with acids and moisture, and controlling acetylene generation and containment to prevent fires or explosions.