Coal and Petroleum


   
 
Hydrocarbons - Homologous Series
Homologous series is a series of organic compounds having the same general formula, arranged in an ascending order of their molecular masses.
 
Each member of the series is called homologue.
 
Characteristics of homologous series
 
All homologues of a series have the same general formula e.g., all alkanes have the general formula CnH2n+2.
 
Each consecutive member differs from the next by one carbon atom and two hydrogen atoms (-CH2 group).
 
The difference in the molecular mass between two consecutive homologues is 14 amu.
 
The physical properties of homologues show a regular gradation.
 
Homologues of a series have similar chemical properties.
 
Homologues of a series have similar methods of preparation.
 
Advantages of homologous series
 
The study of organic compounds becomes easier with the knowledge of homologous series. The study of a vast number of organic compounds become restricted to the study of a few series of homologues.
 
Examples of homologous series
 
Alkanes, alkenes, alkynes, alcohols, aldehydes, carboxylic acids etc. form separate homologous series.
 
 
     
   
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