Question

What is the difference between the mass of two successive members of homologous series?

Answer 1

As you all know that, homologous series are the series of the compound which have similar chemical properties and some functional groups differ from the successive members of $- C{H_2}$ group.

Complete answer:
Let’s first discuss the homologous series of the carbon compound. A homologous series is a sequence of the compounds with the same functional group and having similar chemical properties. The members of the series can be branched and unbranched. Carbon chains of different lengths have been observed in organic compounds having the same general formula.
The general formula for alkanes is ${C_n}{H_{2n + 2}}$, alkenes with ${C_n}{H_{2n}}$ and alkynes with ${C_n}{H_{2n - 2}}$. So, alkanes, alkenes and alkynes form the most basic homologous series in organic chemistry. Homologous series shows all the gradation in physical properties and similar in chemical properties and two adjacent members differ by a $- C{H_2}$ group. An individual member of this series is called homologous and this phenomenon is called homology.
Now, we come to know from the above discussion that the successive members of a homologous series differ by a $- C{H_2}$group. The mass of $- C{H_2}$ group is $14$unit mass. So, the successive members of a homologous series differ by a $14$ unit mass.
Therefore, the difference between the mass of two successive members of homologous series is $14$ unit mass.

Note:
Remember that the chemical properties are similar for the members of a homologous series because all the members have the same functional group whereas physical properties such as melting point and boiling point vary due to the increase in the molecular mass of the compounds.