Homologous Series

  1. A series of compounds with similar chemical properties, in which members differ from one another by the possession of an additional CH2 group, is called a homologous series. 
  2. Each homologous series must have the following four characteristics:
    1. Every member in the homologous series can be represented by a common formula. For example: 
      1. Alkane: CnH2n+2
      2. Alkene: CnH2n
      3. Alcohol: CnH2n+1OH
      4. Carboxylic acid : CnH2n+1COOH
      5. Ester: CnH2n+1COOCmH2m+1
    2. Every member differ from others by the group -CH2- which has the relative mass 14. For example:
    4. Members of the same homologous series can be prepared through one common method. For examples, All alkenes can be prepared by dehydration of relevant alcohols.
    5. Preparing Ethene (Dehydration of ethanol): 

      C2H5OH → C2H4 + H2O 

      Preparing Propene (Dehydration of propanol) 

      C3H7OH → C3H8 + H2O 

    1. Members of the homologous series have the same chemical properties. For example:All alkenes show addition reaction as added into bromine.