distillation - practical

• what is simple distillation used to separate?

  used to separate out a liquid from a solution
• why is distillation used?


  it is used to separate mixtures which contain liquids
• what is the process of simple distillation?


  1. the solution is heated. the part of the solution that has the lowest boiling point evaporates first.
  2. the vapour is then collected, condenses and is collected
  3. the rest of the solution is left behind in the flask
• when can you use distillation?


  to separate pure water from sea water
• what is one problem faced with distillation?


  you can only use it to separate things with different boiling points - if the temperature goes higher than the boiling point of the substance with the higher boiling point, they will mix again
• why is fractional distillation used?


  used to separate a mixture of liquids
• What is the first step in the process of fractional distillation?

  Put the mixture in a flask and stick a fractionating column on top
• Why do different liquids evaporate at different temperatures during fractional distillation?

  Because they have different boiling points
• Which liquid evaporates first in fractional distillation?

  The liquid with the lowest boiling point
• What happens when the temperature on the thermometer matches the boiling point of the liquid?

  The liquid will reach the top of the column
• Why do liquids with higher boiling points not reach the top of the column?

  Because the column is cooler towards the top
• What should you do after the first liquid has been collected in fractional distillation?

  Raise the temperature until the next liquid reaches the top
• What is the overall process of fractional distillation?

  1. Place mixture in a flask with a fractionating column.
  2. Heat the mixture.
  3. Different liquids evaporate at different temperatures due to varying boiling points.
  4. The liquid with the lowest boiling point evaporates first.
  5. Monitor the thermometer; when it matches the boiling point, the liquid reaches the top.
  6. Higher boiling point liquids partially evaporate but condense back down.
  7. After collecting the first liquid, raise the temperature for the next one.