. What is meant by homologous series of organic compounds? Write the chemical formulae of two members of a homologous series


and state which  part determines the (i) physical  properties, (ii) chemical  properties, of these compounds.                         

Best Answer

Ans. A homologous  series  is a group  of organic  compounds having  similar  structures and

similar chemical properties  in which the successive compounds differ by CH2 group. Example: The general formula  of the homologous  series of alkenes is CnH2n+2 where n is the number of carbon atoms.

1st member is CH4,

2nd  member is C2H6

(1)  The members of a homologous series show  a gradual  change in their physical properties with increase in molecular mass, e.g., as the number of carbon atoms increases, the melting points, boiling points and densities of its members increase gradually.

(ii)  All the compounds of homologous series show similar chemical properties  because the basic structure of all the members of a homologous series is similar.

 

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