Chemistry Notes

Unsaturated Hydrocarbons – Alkenes


  • Nomenclature
  • Preparation
  • Properties
  • Uses.


These are hydrocarbons in which carbon atoms join with each other by multiple bonds.  The multiple bond can be double bonds e.g Alkene or triple bonds e.g Alkyne.


The process of naming in alkene is obtained by substitute “ane” in alkane with ‘ene’ e.g Ethane changes to Ethene, propane to prepene

Physical Properties

1.         Ethene is a colourless gas with faint sweetish odour .

2.         It is sparingly  soluble in water

3.         It is slightly less dense than air

4.         It has no action on litmus paper


1.         Write four (4) physical properties of Ethene

2.         How would you prepare a jar of ethane gas in the laboratory?


  • Used in the manufacture of plastics.
  • Used in making synthetic rubber.
  • Used to hasten the ripening of fruits.
  • Used in the production of other organic compounds e.g halo-alkane,ethane, ethanol.


1.  Describe the reaction of ethane with the following:

  1. Bromine water
  2. Chlorine water
  3. Acidified KMnO4
  4. State four (4) uses of Ethene.


New School Chemistry by O.Y. AbabioPg 459-492


1. Describe two (2) methods of obtaining ethene industrially.

2a. Write and name the geometric isomers of compound with the molecular formular  C5H10

  b. With chemical equation only, show how ethane reacts with the following:

            – ozone

            – oxygen

            – alkaline KMnO4

            –  Conc. H2SO4

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