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

Homologous Series : Homologous series is a group of organic compounds having similar structures and similar chemical properties in which the successive compounds differ by $CH_{2}$ OR 14 u.

Characteristics of Homologous Series :

1) All the members of a homologous series can be represented by the same general formula.

2) Any two adjacent homologous differ by 1 carbon atom and 2 hydrogen atoms in their molecular formula.

3) The difference in the molecular masses of any two adjacent homologous is 14 units.

4) All the compounds of a homologous series show similar chemical properties.

5) The members of a homologous series show a gradual change in their physical properties with increase in molecular mass.
 THE PART OF CARBON COMPOUNDS THAT DETERMINES THEIR (i)PHYSICAL PROPERTIES IS HYDROCARBON AND (ii) CHEMICAL PROPERTIES IS FUNCTIONAL GROUP.