A chemist wants to separate ethanol from a mixture of ethanol and water. Explain why simple distillation is a suitable technique for separating this mixture, and describe the key steps involved in carrying out simple distillation.

Eduqas A-Level Chemistry — 1.6 Kinetics · Explain · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Ethanol has a boiling point of 78 °C. Water has a boiling point of 100 °C.

Model answer (5 marks)

Simple distillation is suitable because ethanol and water have different boiling points.
1. The mixture is heated in a flask.
2. The liquid with the lowest boiling point, ethanol, evaporates first.
3. The ethanol vapour rises through the condenser.
4. The vapour is cooled and condenses back into a liquid.
5. The condensed liquid (ethanol) is collected in a separate receiver, leaving water behind in the distillation flask.

Examiner tips

  • Use the term ‘simple distillation’ and mention the boiling point difference. Show the sequence: heating → evaporation of ethanol → condensation → collection. Remember to state that water remains in the flask.
  • common_mistakes
  • :
  • Confusing the order of steps (e.g., collecting before condensation). Using ‘fractional’ instead of ‘simple’ distillation. Failing to mention that ethanol has the lower boiling point.

Mark scheme (5 marks)

  1. Simple distillation is suitable because ethanol and water have different boiling points
  2. The mixture is heated and the liquid with the lowest boiling point (ethanol) evaporates first
  3. The ethanol vapour moves away from the solution
  4. The vapour is cooled and condensed back into a liquid
  5. The condensed liquid (ethanol) is collected separately, leaving water behind in the flask

Key terms in this question

simple distillation

Related

More Kinetics questions

▶ Try answering this question with AI marking (free) →