Question

Write the formula of two homologous of ethane

Answer 1

Step 1:

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

Ethane $\left({\mathrm{C}}_2{\mathrm{H}}_6\right)$ is a saturated compound.

If a compound adds or subtract by one unit of ${\mathrm{CH}}_2$ from that compound then it is a homologous compound.

Step 2:

The homologous of ethane compound is:

• $$\begin{gathered} {\mathrm{C}}_2{\mathrm{H}}_6+{\mathrm{CH}}_2\to {\mathrm{C}}_3{\mathrm{H}}_8 \\ \mathrm{Ethane}\mathrm{propane} \\ (\mathrm{lower}\mathrm{homologue})(\mathrm{higher}\mathrm{homologue}) \end{gathered}$$
• $$\begin{gathered} {\mathrm{C}}_3{\mathrm{H}}_8+{\mathrm{CH}}_2\to {\mathrm{C}}_4{\mathrm{H}}_{10} \\ \mathrm{Propane}\mathrm{Butane} \\ (\mathrm{lower}\mathrm{homologue})(\mathrm{higher}\mathrm{homologue}) \end{gathered}$$

Hence, the two homologous of ethane is ${\mathrm{C}}_3{\mathrm{H}}_8$ and ${\mathrm{C}}_4{\mathrm{H}}_{10}$.