Separating mixtures: techniques teaching resources

Worksheets and lesson ideas to challenge students aged 11 to 16 to think hard about separating mixtures (GCSE and Key Stage 3)

The worksheets and ideas below on separating techniques (chromatography, distillation, filtration and crystallisation) provide an ideal opportunity to challenge students with practical work. The relatively safe nature of the practical work means students can be set challenges to separate X from Y with the ‘off you go approach‘. Reflecting on the successes of the practical can lead to greater learning than would be achieved if students had just followed a method.

Chromatography

This video demonstrates an easy method to extract chlorophyll from leaves. The extracted pigments can then be separated using chromatography.

KS3 practical on the chromatography of ink. Students carry out a simple practical to separate the ink from different felt tip pens. This method can be modified to extract chlorophyl from leaves (see above). (PDF)

KS3 activity to interpret chromatograms. Students apply their knowledge of chromatography to a new context involving food colours and hyperactivity. They use evidence from a chromatogram to determine whether two drinks are safe for a child. This resource was contributed by Jill White. It is an excellent way of helping students use evidence to support a claim. (PDF)

Distillation

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)

Fractional distillation

Follow this link for resources and worksheets on the fractional distillation of crude oil.

Filtration and crystallisation – separating soluble salts

KS3 practical activity to separate salt and sand. This practical is an open activity that asks students to come up with their own method to separate salt from sand. To increase the challenge, students should be allowed to select the apparatus they want to use. It’s worth pointing out the difference between evaporation and cystallisation. At the end of the practical the percentage yield of each group is calculated and a winner declared. You could use this method for teaching about preparation of solution salts. (PDF)

Selecting the appropriate separating technique

GCSE activity where students select the appropriate separating technique. Students select the appropriate technique to separate mixtures by chromatography, distillation, fractional distillation, filtration and crystallisation. It finishes with a really challenging question that asks students to suggest ideas on how to separate copper from a mixture containing magnesium, salt, water and copper. (PDF)

The separating technique challenge!

The separation challenge!

  1. Key Stage 3 practical challenge to separate a mixtures.
  2. Accompanying help sheet on chromatography

Students are given a range of practical equipment and work in pairs to separate a complex mixture containing sand, sulfur, two food dyes and iron. This activity was made in collaboration with Claire Couves and Rownok Jahan.

  1. Particle pictures and the particle model
  2. Elements mixtures and compounds
  3. Separating techniques
  4. Solutions
  5. Density