Calcium Carbide: Properties, Production, and Uses
Calcium carbide (CaC₂) is an industrial chemical compound primarily known for its role in the production of acetylene gas. A greyish-white, crystalline solid, calcium carbide reacts vigorously with water to produce acetylene (C₂H₂) — a valuable gas used in welding and as a chemical building block.
Chemical Properties
Chemical Formula: CaC₂
Molar Mass: 64.10 g/mol
Appearance: Grey, brown, or black solid (pure form is colorless)
Odor: Garlic-like smell due to impurities
Density: ~2.22 g/cm³
Melting Point: ~2,300°C (4,172°F)
Reactivity: Reacts with water to form acetylene and calcium hydroxide.
Reaction with Water:CaC2+2H2O→C2H2+Ca(OH)2\text{CaC}_2 + 2H_2O \rightarrow C_2H_2 + Ca(OH)_2CaC2+2H2O→C2H2+Ca(OH)2This reaction is highly exothermic and must be carefully controlled.
Production
Calcium carbide is manufactured industrially in electric arc furnaces by heating a mixture of lime (CaO) and coke (carbon source) at around 2,000°C:CaO+3C→CaC2+COCaO + 3C \rightarrow CaC_2 + COCaO+3C→CaC2+CO
This high-temperature process was first developed in the late 19th century and remains the standard method today.