Seperation of Mixtures

• Chromatography:

  • Used to separate different dyes in ink

  1. Draw pencil line at bottom of filter paper
  2. Add spots of ink to line and place sheet in beaker of solvent - make sure solvent is under pencil line
  3. When solvent has nearly reached top of paper, leave to dry

  • If any dyes are insoluble, they will stay on base line
• Filtration:

  • Used to separate insoluble solid from solute
  • Can be used to purify solid impurities
• Evaporation:

  • Used to separate soluble salt from solution

  1. Pour solution into evaporating dish
  2. Slowly heat solution to boiling point of solvent
  3. Solvent will evaporated and solution will get more concentrated
  4. Keep heating until dry crystals are formed
• Crystallisation:

  • Used to separate soluble salt from solution

  1. Pour solution into evaporating dish and gently heat solution
  2. Solvent will evaporate and solution will get more concentrated
  3. Once some of solvent has evaporated or point of crystallisation is reached, remove dish from heat and leave solution to cool
  4. Filter crystals from solution and leave to dry
• • To separate different compounds - soluble and insoluble - filtration and crystallisation is used
• Simple Distillation:

  • Used to separate liquid from solution

  1. Solution is heated, part of solution with lowest boiling point evaporates first
  2. Vapour is cooled, condensed and collected
  3. Rest of solution is left behind in flask
• Fractional Distillation:

  • Used to separate mixture of liquids with very different boiling points

  1. Place mixture in flask with fractionating column in top, then heat
  2. Different liquids have different boiling points so all will evaporate at different temperatures
  3. Liquid with lowest boiling point evaporates first - when temperature on thermometer matches boiling point of this liquid, it will reach top of column
  4. Liquids with higher boiling points will start to evaporate but will only get part way up before condensing as column is cooler
• Mixtures can be separated by physical processes:

  • Filtration
  • Simple distillation
  • Fractional distillation
  • Chromatography
  • Crystallisation