Fractional Distillation

• Fractional distillation


  A technique used to separate a mixture of different liquids based on their different boiling points
• Fractional distillation

  • Requires a mixture of liquids with different boiling points
  • Uses a fractionating column containing glass beads to increase the separation of the liquids
• Fractional distillation process

  1. Heat the mixture

  2. Vapors of lower boiling point liquid rise up the fractionating column first

  3. Vapors condense and drip back into the flask

  4. Repeated evaporation and condensation increases the concentration of the lower boiling point liquid

  5. Thermometer measures the temperature, which rises and then plateaus at the boiling point of the lower boiling point liquid

  6. Collect the first fraction of the lower boiling point liquid

  7. Temperature rises again as the higher boiling point liquid vaporizes

  8. Thermometer plateaus at the boiling point of the higher boiling point liquid

  9. Collect the second fraction of the higher boiling point liquid
• If the two liquids have very similar boiling points, it is much harder to separate them and may require multiple rounds of fractional distillation
• The equipment shown is not suitable for separating very large volumes of liquid, such as when refining crude oil