Physical Separation Techniques

Overview

• Series of videos on physical separation techniques
• Techniques covered: Filtration, Crystallisation, Distillation, Chromatography

Simple Distillation

• Used to separate a liquid from a solid when the liquid needs to be kept.
• Two main stages:
  1. Evaporation of the liquid by heating
  2. Condensation of the vapour back to liquid by cooling
• Apparatus:
  • Flask containing the solution (liquid and dissolved solid)
  • Continuous glass tube connected to the flask
  • Condenser (jacket surrounding the glass tube with cold water running through it)
  • Thermometer
• Process:
  1. Heat the solution (using a Bunsen burner)
  2. Liquid evaporates, turning into vapour
  3. Vapour rises up the glass tube
  4. Thermometer shows rising temperature (usually boiling point)
  5. Vapour passes into the condenser
  6. Cold water in the condenser causes vapour to condense back into liquid
  7. Collect the liquid in a beaker
• Outcome:
  • Crystals of the solid remain in the flask
  • Liquid is collected in the beaker
• Practical Application:
  • Can be used to produce drinking water from sea water
  • Requires a great deal of energy, so generally not used for making drinking water.

Next Steps

• The next video will cover fractional distillation (used to separate two different liquids).