The best pens for this activity are (1) A black felt tip pen (2) A black permanent pen (3) A Non-permanent black pen. These look the same on paper but have different chromatography results.
- Handout | PDF, Size 3.55 mb
These resources were created for the Cambridge science festival 2014, and are featured resources in our autumn 2015 'Get colourful with chemistry' theme.
If you teach primary science, see the headings below to find out how to use this resource:
Children will develop their working scientifically skills by:
- Using appropriate scientific language and ideas to explain, evaluate and communicate their methods and findings.
- Drawing conclusions and raising further questions that could be investigated, based on their data and observations.
- Asking their own questions about scientific phenomena.
- Use knowledge of solids, liquids and gases to decide how mixtures might be separated.
- Compare and group together everyday materials on the basis of their properties, including their solubility.
Children will learn:
- That certain colours and dyes are made up from a mixture of colours and these can be separated by using chromatography.
Suggested activity use
This activity could be used with a whole class. Children could work in small groups investigating how to separate the colours in the black pens provided. The activity provides a useful exercise in children applying their previous knowledge of chromatography to help solve the ‘crime scene’ problem you have set.
You may need to experiment with a range of black pens beforehand, as some pens work better than others. Also you will need to prepare the letter, using a pen that matches or has been included as one of the suspected pens.
Filter paper will be required as certain papers are not absorbent enough to separate the colours out effectively.
Previous work on chromatography may be beneficial.