Distillation

• Simple distillation

  1. A solution is heated, usually using a  burner.
  2. The liquid in the mixture  into a gas. 
  3. The gas is cooled by a water jacket, and  into a liquid, which then flows into the beaker. 
• Fractional distillation can separate a mixture of several liquids that each have different:

  Boiling points
• Briefly explain the process of fractional distillation to separate a mixture of the liquids methanol, ethanol and propanol.

  Heat is applied and the liquid with the lowest boiling point evaporates and condenses into a beaker.

  If other liquids evaporate by chance, they condense in the fractionating column back into the flask.

  The temperature is altered to repeat the process for the second liquid. 

  The three liquids are separated based on differing boiling points with the third remaining in the flask. 
• How would you isolate pure water from salt water?

  Simple distillation
• Describe the process of simple distillation

  1. The solution in placed in a flask and heated so that the liquid evaporates into vapour.
  2. The vapour will pass into a condenser where it condenses back into liquid.
  3. The liquid is collected in a beaker.
• What is the fractionating column used in laboratory fraction distillation filled with? Explain why

  The fractionating column is filled with small glass rods. These provide a large surface area which will cause gases to condense back into liquid if the temperature is below their boiling point.
• When would you need to use fractional distillation rather than simple distillation?

  Fractional distillation is used when the mixture contains multiple liquids with similar boiling points.
• How does fractional distillation work?

  1. The solution is placed in a flask and gently heated.
  2. The liquid with the lowest boiling point evaporates into a vapour and passes through the fractionating column.
  3. As it passes into the condenser it condenses back into a liquid, and is collected in a beaker.
  4. If another liquid had evaporated, it would have condensed again while passing through the fractionating column.
  5. As the temperature is increased, the process repeats for the liquid with the second lowest boiling point, which is collected in a different beaker and so on.
• What is the purpose of simple distillation?

  Simple distillation is used to separate a liquid from a mixture, but when we want to keep the liquid.
• Why can you not use simple distillation for mixtures that contain multiple different liquids?

  If the different liquids have similar boiling points, those liquids may evaporate at the same time