Question

Why homologous series of carbon compounds are so called? Write chemical formula of two consecutive members of a homologous series and state the part of these compounds that determines their (i) physical properties, and (ii) chemical properties?

Answer 1

A homologous series is a group of organic chemical compounds, usually listed in order of increasing size, that have a similar structure and general formula (and hence also similar properties) and whose structures differ only by the number of $-C{H}_2$ units in the main carbon chain.

$C{H}_{3}C{H}_{2}OH$ and $C{H}_{3}C{H}_{2}C{H}_{2}OH$ are two consecutive members of alcohol homologous series.

Physical properties:- Hydrocarbon chain i.e. $C{H}_3$ in $C{H}_{3}C{H}_{2}OH$ and $C{H}_{3}C{H}_2$ in $C{H}_{3}C{H}_{2}C{H}_{2}OH$

Chemical properties:- Functional group i.e. $-OH$