Question

(a) Define a homologous series. Give the name and structural formula of one homologue of the following:
CH₃OH
(b) Write the molecular formula of the third member of the homologous series of carbon compounds with general formula C_nH_2n+1OH.
(c) Name any two fossil fuels.

Answer 1

(a) Homologous series: A series of organic compounds having similar structures and chemical properties and in which the successive compounds differ by -CH₂ group is called a homologous series. A homologue of CH₃OH will differ by the -CH₂ group; therefore, methanol's successive homologue will be ethanol (C₂H₅OH).
The structural formula of ethanol is as follows:



(b) The molecular formula of the third member of the homologous series, comprising the general formula C_nH_2n+1OH, is C₃H₇OH (propanol).

(c) Coal and petroleum are the two fossil fuels.