Question

Ethylene is prepared by:

• A. dehalogenation of chloroform
• B. pyrolysis of ethane at ${450}^{0}C$
• C. dehydration of methanol with ${Al}_2{O}_3/{350}^{0}C$
• D. methyl chloride on reduction

Answer 1

The correct option is B pyrolysis of ethane at ${450}^{0}C$

Decomposition of the compound by heat is called pyrolysis or thermal decomposition.

When Ethane is heated in absence of air at ${450}^{\circ }C$ gives Ethylene and Hydrogen.

$C{H}_3-C{H}_3\stackrel{{450}^{\circ }C}{\to }C{H}_2=C{H}_2+H_2$

When Alkanes are heated to high temperature in absence of air, the higher alkane molecules break up into smaller molecules of lower alkanes, alkanes, and hydrogen.

Remaining all reactions gives alkanes