Sodium carbide, Na₂C₂

When acetylene reacts with sodium, either in the metallic state, or as hydride, or in solution in liquid ammonia, a substance of the formula C₂Na₂,C₂H₂ is produced. When heated in vacuum, or in a current of hydrogen at 220° C., it evolves acetylene, leaving sodium carbide. The carbide is very reactive, readily undergoing decomposition with deposition of carbon, and decomposing water with evolution of acetylene.