Draw formulas for the first five members of each homologous series beginning with the following compounds A) HCOOH      B)CH3COCH3       C)HCHCH2


Homologous series- Carbon atoms can be linked together to form chains of varying lengths. These chains can be branched also. In addition hydrogen atom or other atom on these carbon chains can be replaced  by any of the functional groups. The presence of a functional group such as alcohol decides the properties of the carbon compound, regardless of CH3OH, C2H5OH, C3H7OH and C4H9OH   are all are very similar. Hence , such  a series of compounds in which the same functional group substitutes for hydrogen in a carbon chains is called homologous series.

A)HCOOH                     –    Methanoic  acid                                    B)CH3COCH     –       Propanone                            

CH3COOH                  –    Ethanoic acid                                                 CH3COCH2CH3 –  Butan-2-one

CH3CH2COOH             – Propanoic acid                                                CH3COCH2CH2CH3– Pentane-2-one

CH3CH2CH2COOH     – Butanoic acid                                                    CH3COC4H9  –   Hexane-2-one

CH3CH2CH2CH2COOH   -Pentanoic acid                                              CH3COC5H11  –  Heptane-2-one

     C)HCHCH2  –   Ethene

CH3CHCH2    –     Propene

CH3CH2CHCH2   – But-1-ene

CH3CH2CH2CHCH2  – Pent-1-ene

CH3CH2CH2CH2CHCH2  – Hex-1-ene

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