Question

The molecules of the alkene family are represented by the general formula ${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}}$. Write the molecular formula of the adjacent higher or lower homologues of an alkene which contains four carbon atoms.

Answer 1

The organic compounds consisting of Carbon $\left(\mathrm{C}\right)$ and Hydrogen $\left(\mathrm{H}\right)$ atoms are known as hydrocarbons.

Hydrocarbons are of two types depending on the kind of bonds formed between Carbon-Carbon atoms, saturated hydrocarbons, and unsaturated hydrocarbons

The organic compounds containing Carbon atoms having double bonds between two Carbon atoms are called unsaturated hydrocarbons.

The molecules of the alkene family are represented by the general formula ${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}}$.

The molecular formula of alkene contains four Carbon atoms is Butene $\left({\mathrm{C}}_4{\mathrm{H}}_8\right)$.

Homologous series of compound lies in the same family and the molecular formula is different by one $\left({\mathrm{CH}}_2\right)$ unit.

The higher homologue of butene $\left({\mathrm{C}}_4{\mathrm{H}}_8\right)$ is formed by the addition of one $\left({\mathrm{CH}}_2\right)$ unit. The higher homologue will be Pentene (${\mathrm{C}}_5{\mathrm{H}}_{10}$).

$$\begin{gathered} {\mathrm{C}}_4{\mathrm{H}}_8+{\mathrm{CH}}_2\to {\mathrm{C}}_5{\mathrm{H}}_{10} \\ \left(\mathrm{Butene}\right)\left(\mathrm{Pentene}\right) \end{gathered}$$

The lower homologue of Butene $\left({\mathrm{C}}_4{\mathrm{H}}_8\right)$ is formed by the subtraction of one $\left({\mathrm{CH}}_2\right)$ unit. The lower homologue will be Propene (${\mathrm{C}}_3{\mathrm{H}}_6$).

$$\begin{gathered} {\mathrm{C}}_4{\mathrm{H}}_8-{\mathrm{CH}}_2\to {\mathrm{C}}_3{\mathrm{H}}_6 \\ \left(\mathrm{Butene}\right)\left(\mathrm{Propene}\right) \end{gathered}$$