separating tenchniques

• Fractional distillation

  Used to Separate complex mixtures such as crude oil. the crude oil is vapourised and passed into a fractional column. They separate according to their B.Ps
• Filtration

  is used to separate an insoluble solid from a liquid. It is useful for separating sand from a mixture of sand and water, or excess solid reactant from a solution.

  Filtration works because the filter paper has tiny holes or pores in it. These are large enough to let simple molecules and dissolved ions through, but not the much larger particles of undissolved 
• Distillation

  Simple distillation can also be used to separate two liquids with a large difference in boiling points, such as ethanol and water. The mixture must be carefully heated and the temperature controlled, so that only the liquid with the lower boiling point evaporates. This can then be collected using a condenser.
• Paper chromatography

  Paper chromatography is another method that can be used to test if a substance is pure or impure. It can also be used to separate mixtures of soluble substances in order to find out what substances are in the mixture. These are often coloured substances such as food colourings, inks, dyes or plant pigments.
• Crystallisation


  Crystallisation is used to produce solid crystals from a solution. When the solution is warmed, the solvent evaporates leaving crystals behind. For example, crystallisation is used to obtain copper sulfate crystals from copper sulfate solution.

  • put the solution in an evaporating basin
  • warm the solution by placing the evaporating basin over a boiling water bath
  • stop heating before all the solvent has evaporated

  The evaporating basin may then be left, allowing the crystals to grow.