3rd of March 2017

What is the significance of homologous series?

Rimjhim Tyagi - CBSE - Class X

Friday, March 03, 2017 at 17:57:PM


It is a group of organic compounds having a similar structure and similar chemical properties in which the successive compounds differ by a -CH2 group.

Characteristics of a Homologous series

  • Each member of the series differs from the preceding one by the addition of a -CH2 group and by 14 a.m.u.
  • All members of a homologous series share the general formula.

      For example, the general formula for alkane is CnH2n+2 and alkene is CnH2n.

  • The physical properties of the members show a gradation in properties as the molecular mass increases.
  • The chemical properties also show a gradient similarity.

       For example: Methane and ethane react with chlorine to form methyl chloride and ethyl chloride respectively.

CH4 + Cl2 → CH3Cl

C2H6 + Cl2 → C2H5Cl

Friday, March 03, 2017 at 18:01:PM