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