Ethyne is prepared by using water and calcium carbide in the laboratory.
Explanation:
Acetylene is conveniently prepared in the laboratory by the action of water(H₂O) on calcium carbide (CaC₂). Calcium carbide in turn is obtained by heating the mixture of coke and lime stone in an electric furnace.
CaC₂ + 2H₂O → Ca(OH)₂ + C₂H₂
Ethyne gas prepared in the lab using the above method may contain impurities like H₂S, PH₃, AsH₃, NH₃etc. The gas is purified by bubbling it through acidified copper sulfate solution.