Worksheets and lesson ideas to challenge students aged 11 to 16 to think hard about distillation (GCSE and Key Stage 3)
Key ideas: distillation is a fantastic concept to teach as it brings together theory and practical work in a really meaningful way. Distillation is a physical process used to separate a pure liquid from a mixture of liquids, based on differences in their boiling point. Distillation is a two step process that involves evaporation followed by condensation. It’s also an incredibly important process which society relies on: production of alcohol, the water cycle, creating potable water.
Misconceptions [scientific idea]:
- distillation is a chemical process – i.e. a new substance is being made [it’s a physical process]
- distillation can separate out any mixture of liquids [there must be a difference in b.pt]
- water runs through the Liebig condenser [water runs along the outside of the condenser]
- temperature increases when a substance boils [temperature remains constant]
Where to start?
It may help students if distillation is introduced without the complex lab apparatus first. The video below is an example of such a set-up. Once students understand this idea, you can move on to explaining condensers, thermometers and round bottom flasks.
A nice context to explore is the distillation of cherry coke – it’s smelling the distillate that’s important!
Liquids have different boiling points
A powerful way to demonstrate that liquids have different boiling points is to put a test tube of petroleum ether (40-60°C) in a beaker of kettle boiled water. Don’t use a Bunsen as petroleum ether is highly flammable. Students will see the petroleum ether bubbling but the water won’t be.
Distillation apparatus and the particle model
GCSE and KS3 worksheet on distillation. Students write a story about the experiences of a particle being distilled. They also consider the implications of an incorrect set-up of the distillation apparatus. (PDF)
Distillation and boiling points
Key Stage 3 worksheet on distillation and making Ribena. Students read about how Ribena is made and use this context to answer questions on distillation and filtration. This task is best used once students have been introduced to the key concepts in distillation: evaporation and condensation. (PDF)
Follow this link for resources and worksheets on the fractional distillation of crude oil.