RP5

• Distillation


  A procedure used separate mixtures of liquids
• Simple distillation


  • Commonly used to isolate a low boiling product after its synthesis or to concentrate a solution of ethanol after fermentation
• Fractional distillation


  • Used to separate the hydrocarbons in crude oil, essentially the same process except a fractionating column is inserted before the condenser
• When setting up a condenser

  It is important the water enters at the lowest point of gravity
• Anti-bumping granules


  Prevent vigorous boiling of the mixture
• When distilling a product

  The entire system must not be air-tight (ie the collection flask should not be sealed to the condenser)
• Boiling points of a reaction mixture

  • Ethanol: 78°C
  • Ethanal: 21°C
  • Ethanoic acid: 118°C
• How to isolate a pure sample of ethanal from the sample minimising the loss of ethanal

  1. Heat the mixture in a round/pear-shaped flask

  2. With a still head containing a thermometer

  3. Attached to a condenser with a ice cooled collecting vessel

  4. Collect sample at the boiling point of ethanal

  5. The cooled collection vessel is essential to reduce evaporation of ethanal
• Thermometer

  The bulb of the thermometer must be in a position to measure temp of the vapour which must not escape through the top
• water bath/electric bath 


  Heat the mixture if it is flammable