Reaction of calcium carbide (CaC2) and water, evolution of ethyne (C2H2 or acetylene):
CaC2(s) + 2H2O(l) → Ca(OH)2(aq, s) + C2H2(g)
or in ionic form:
CaC2(s) + 2H2O(l) → Ca2+(aq) + 2OH–(aq) + C2H2(g)
Due to the rather high carbon content, the combustion of ethyne in air (air oxygen) is incomplete:
2C2H2(g) + 3O2(g) → 2C(s) + 2CO2(g) + 2H2O(g)
Caution! Ethyne is highly flammable gas!