1.6 Distillation

• What are the two types of distillation used to separate liquid mixtures?

  Simple distillation and fractional distillation
• What is the purpose of simple distillation?

  To separate a liquid from a solution
• How can simple distillation be used with seawater?

  To separate pure water from seawater
• What equipment is needed for simple distillation?

  • Flask containing the solution
  • Bung to seal the flask
  • Thermometer to measure temperature
  • Condenser with a water jacket
  • Beaker to collect the distilled liquid
  • Heating device (e.g., Bunsen burner)
• What is the function of the thermometer in the distillation setup?

  To measure the temperature inside the flask
• How does the condenser work in simple distillation?

  The vapor cools and condenses into liquid form as it passes through the condenser
• What happens to the seawater during the distillation process?

  Pure distilled water is collected while salt remains in the flask
• Why can't simple distillation separate liquids with similar boiling points?

  Because more than one liquid will evaporate at the same time
• What is the main technique used for separating mixtures of liquids?

  Fractional distillation
• What are the key features of a fractionating column?

  • Full of little glass rods for high surface area
  • Cooler at the top than at the bottom
• How does the temperature affect the separation of methanol, ethanol, and propanol in fractional distillation?

  Different temperatures are used to evaporate each liquid based on their boiling points
• What happens to methanol when the mixture is heated to around 65 degrees Celsius?

  Methanol evaporates and rises up the fractionating column
• Why do some ethanol and propanol molecules condense back into liquid form in the fractionating column?

  Because they come into contact with cooler glass rods
• What is the next step after collecting methanol in fractional distillation?

  Raise the temperature to around 78 degrees Celsius to evaporate ethanol
• What can be assumed about the contents of the flask after collecting ethanol?

  That it contains mostly pure propanol
• What could be done to ensure that only propanol is collected at the end of fractional distillation?

  Raise the temperature again to boil off the propanol
• What is the overall process of fractional distillation for separating methanol, ethanol, and propanol?

  1. Heat the mixture to 65°C to evaporate methanol.
  2. Methanol rises, condenses in the condenser, and collects in the beaker.
  3. Raise the temperature to 78°C to evaporate ethanol.
  4. Collect ethanol, leaving propanol in the flask.
  5. Optionally, raise the temperature again to collect pure propanol.