Question

What is meant by a homologous series? Illustrate by giving one example.

Answer 1

Part 1: Definition of homologous series

1. A homologous series may be defined as a group of organic compounds consisting of the same functional group.
2. Each member of a homologous series differs from each other by a $-{\mathrm{CH}}_2$ group.
3. The chemical properties of all the members of a homologous series are the same.
4. A member of any homologous series is known as a homologue.

Part 2: Example of homologous series

1. A common general formula is used to describe all the members of a homologous series.
2. For example, all the alkanes can be described by the general formula${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}+2}$, where the $\mathrm{n}=$number of Carbon atoms.
3. The value of $\text{'}\mathrm{n}\text{'}$is greater than$1$, i.e. $\mathrm{n}=2,3,4,......$