Alkenes

• what is an alkene?

  • unsaturated hydrocarbon, contain C=C bond
  • general formula CnH2n
• what is the test for alkenes?

  • add bromine water
  • colour change occurs from orange to colourless
• describe the combustion of alkenes

  burn with smoky flames due to incomplete combustion
• describe addition reactions of alkenes

  additions atoms across the carbon-carbon double bond so that the double bond becomes a single carbon-carbon bond

  1. with hydrogen - hydrogenation; requires a higher temperature and a nickel catalyst
  2. with steam - hydration; requires high temperature, pressure and concentrated phosphoric acid (H3PO4) as a catalyst
  3. with Br2/Cl2/I2 - addition of halogens