Question

Write the following reaction of ethene:

Hydrogenation

Answer 1

Step 1:

Alkanes contain only single bonds between Carbon $\left(\mathrm{C}\right)$ atoms. Therefore, alkenes are considered a saturated hydrocarbon.

Alkenes contain double bonds between the Carbon atoms. So it is an unsaturated hydrocarbon.

In the reaction of an alkene with a Hydrogen $\left(\mathrm{H}\right)$ atom, in the presence of a metal catalyst, the Hydrogen molecule is added to the unsaturated double bond to form the saturated alkane product. So, this addition reaction is known as a hydrogenation reaction.

Step 2:

The hydrogenation reaction of Ethene $\left({\mathrm{C}}_2{\mathrm{H}}_4\right)$ forms Ethane $\left({\mathrm{C}}_2{\mathrm{H}}_6\right)$ as the major product.

The hydrogenation reaction of Ethene can be written as:

$$\begin{gathered} {\mathrm{CH}}_2={\mathrm{CH}}_2+\mathrm{H}-\mathrm{H}\to {\mathrm{CH}}_3-{\mathrm{CH}}_3 \\ \left(\mathrm{Ethene}\right)\left(\mathrm{Hydrogen}\right)\left(\mathrm{Ethane}\right) \end{gathered}$$