How is ethyne prepared in the laboratory?

(a) Draw a diagram

(b) Give an equation

(c) How is pure dry gas collected?

(a) Below diagram shows the setup for laboratory preparation of ethyne:

(b) Ethyne [C₂H₂] from Calcium Carbide :

$\underset{\text{calcium carbide}}{\text{CaC}$2} + \underset{\text{water}}{2\text{H}2\text{O}} \longrightarrow \underset{\text{ethyne}}{\text{C}2\text{H}2} + \underset{\text{calcium hydroxide}}{\text{Ca(OH)}_2}

(b) As the pure dry gas is insoluble in water, it is collected by downward displacement of water.