The many compounds of carbon and hydrogen are called hydrocarbons. Carbon unites with elements, particularly metals, to form carbides, such as calcium carbide and silicon carbide. Calcium carbide is made by heating lime and coke or coal in an electric furnace. It is a brittle, dark gray, crystalline solid which forms acetylene gas on the addition of water.

CaC2

+

2 H1O

=

C2H1

+

Ca(OH)2

Calcium Carbide

Water

Acetylene

Calcium Hydroxide