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Chemistry LibreTexts

Underwater Fireworks

Reaction

Acetylene gas is generated by reacting calcium carbide (CaC2) with water. The equation is

CaC2 (s) + 2 H2O (l) -> Ca(OH)2 (aq ) + C2H2 (g )

The resulting acetylene gas and chlorine gas (introduced directly as gas) react upon contact to generate flames (underwater) and the formation of solid carbon and hydrochlotic acid.

C2H2 + Cl2 -> -> 2 HCl (g) + 2 C(s )

Safety

The resulting liquid is acidic (how much depends on how long the reaction occurs) and needs to be neutralized before disposal.