Question

$H_{2}C=C{H}_2+H_2\stackrel{Ni/{300}^{0}C}{\to }{C}_2{H}_6$ to get back the ethene, ethane must be:

• A. dehydrogenated in the presence of $Cu$ at ${300}^{0}C$
• B. heated to ${450}^{0}C$ in the presence of $HN{O}_3$ vapoar
• C. heated ${170}^{0}C$ in the presence of conc. $H_{2}S{O}_4$
• D. heated to ${750}^{0}C$

Answer 1

Answer: (D)

heated to ${750}^{0}C$

Alkanes formed from alkenes, can be reverted back to alkenes by catalytic cracking or thermal decomposition, when heated in the absence of air, gives a mixture of ethylene and hydrogen.

Cleavage of C-H bonds: This type of fission results in the formation of alkenes. It is catalyzed by the oxides of chromium, vanadium, molybdenum.