organic chemistry

• explain how fractional distillation of crude oil takes place?

  • crude oil is heated and vapourised.
  • vapour rises up the fractionating column.
  • the column is hotter at the bottom and cooler at the top.
  • Hydrocarbons cool as they go up the column and condense at different heights, as they have different boiling points.
  • large molecules, high boiling points - are collected at the bottom.
  • small molecules, low boiling points - are collected at the top.
• what are alkanes?


  saturated hydrocarbons of a general formula: CnH2n+2
• what is a homologous series?

  a series of compounds with the same general formula, same functional groups and similar chemical properties.
• what is crude oil?

  crude oil is a mixture of compounds; a fossil fuel consisting of the remains of ancient biomass.
• what is a hydrocarbon?


  a compound made up of exclusively of hydrogen and carbon atoms.
• what is an alkene?

  an unsaturated hydrocarbon. Contains a C=C bond.
• what is the test for alkenes?

  • add bromine water. Colour change occurs from orange to colourless.