2010-08-07

Characteristics of Homologous Series

In Chemistry SPM, students were introduced with five homologous series: Alkane, Alkene, Alcohol, Carboxylic Acids and Esters.

The following is one of the Chemistry SPM 2009 questions related to homologous series.
The table shows some information about three members of a homologous series.
Homologous Series

Based on the table, state and explain five characteristics of a homologous series.                                        [10 marks]
  1. Members of the series can be represented by a general formula. Ethanol, propanol and butanal have the same general formula, CnH2n+1OH
  2. Successive members differ from each other by –CH2. The difference between propanol and ethanol is CH2 that has a relative molecular mass of 14.
  3. Physical properties change regularly with increasing number of carbon atoms. The boiling points of alcohols increase from ethanol, propanol to butanol.
  4. Members have similar chemical properties because they have same functional group. Ethanol, propanol and butanol undergo oxidatoin produce carboxylic acids.
  5. Members of the homologous series can be prepared using the same method.  Ethanol, propanol & butanol can be prepared by hydration of alkene.

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