Calcium Carbideore is yellow-brown or black bulk solid, pure white crystal (containing higher CaC2 is purple). Density 2.22g/cubic cm, melting point 2300oC (related to the content of CaC2), immediately react with water, generate acetylene, and release heat, calcium carbide content different melting point also changes.

Impurities: because calcium carbide often contains calcium arsenide (Ca3 As2), calcium phosphide (Ca3 P2) and other impurities, and water action at the same time release hydrogen arsenide (AsH3), phosphide (PH3) and other toxic gases, so the use of acetylene produced by calcium carbide is toxic.