Question

4. How is acetylene prepared from the following ?
(a). Calcium carbide (b) Ethylene dibromide
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Answer 1

The simplest process reacts calcium carbide with water to produce acetylene gas and a calcium carbonate slurry, called hydrated lime. ... The chemical reaction for converting methane into acetylene and hydrogen may be written 2 CH 4 → C 2 H 2 + 3 H 2 . The other gases are the products of combustion with oxygen.

Answer 2

(a). Acetylene ( C$_{2}$H$_{2}$ ) can be prepared by calcium carbide ( CaC$_{2}$ ) by following step of reaction -

React calcium carbide ( CaC$_{2}$ ) with water ( H$_{2}$O ) , acetylene ( C$_{2}$H$_{2}$ ) is formed .  

CaC$_{2}$ + 2 H$_{2}$O  →  C$_{2}$H$_{2}$ + Ca(OH)$_{2}$

(b). Acetylene ( C$_{2}$H$_{2}$ ) can be prepared by ethylene dibromide ( CH$_{2}$ Br−CH$_{2}$Br ) by following step of reaction -

React ethylene dibromide ( CH$_{2}$ Br−CH$_{2}$Br ) with hot concentrated alcoholic potassium hydroxide ( KOH ) followed by liquid NaNH$_{2}$ , acetylene ( C$_{2}$H$_{2}$ ) is formed .  

CH$_{2}$ Br−CH$_{2}$Br + KOH  →  CHBr = CH$_{2}$  + KBr

CHBr = CH$_{2}$   + NaNH$_{2}$   →  CH≡CH + NaBr + H$_{2}$