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?

  It can separate pure water from seawater
• What equipment is used in simple distillation?

  A flask, thermometer, condenser, beaker, and heating device
• Why is the flask sealed with a bung in simple distillation?

  To prevent gas from escaping
• What is the function of the thermometer in simple distillation?

  To measure the temperature inside the flask which is stuck through the bung
• How does the condenser work in simple distillation?

  It cools and condenses vapor into liquid form and also has a water jacket which is pumped with cold water from the bottom and coming out the top
• What happens to the vapor as it passes through the condenser?

  It cools and condenses into liquid
• Why can't simple distillation be used for mixtures of liquids with similar boiling points?

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

  Fractional distillation
• What is the role of the fractionating column in fractional distillation?

  It allows for better separation of liquids with similar boiling points
• What are the two key features of the fractionating column?

  It is filled with glass rods which have a really high surface area and is cooler at the top than at the bottom due to its height
• What happens to methanol as it rises up the fractionating column?

  It evaporates and passes into the condenser
• Why do some ethanol and propanol molecules condense back into liquid in the fractionating column?

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

  To raise the temperature to around 78 degrees Celsius to collect ethanol
• What can be assumed about the liquid left in the flask after collecting ethanol?

  It is pure propanol
• What could be done to ensure that only propanol is collected after ethanol?

  Raise the temperature again to boil off the propanol
• What are the steps involved in simple distillation?

  1. Heat the mixture in the flask.
  2. The desired liquid evaporates and rises.
  3. Vapor passes through the condenser.
  4. Vapor cools and condenses into liquid.
  5. Collect the distilled liquid in a beaker.
  6. Residue remains in the flask.
• What are the steps involved in fractional distillation?

  1. Heat the mixture in the flask.
  2. Vapor rises through the fractionating column.
  3. Vapor condenses on cooler glass rods.
  4. Pure liquid passes into the condenser.
  5. Collect the distilled liquid in a beaker.
  6. Repeat for other components by adjusting temperature.