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