Chemists needed a way to separate substances such as dyes and chemical mixtures into their separate parts. In this experiment, we’ll mix two different food colours and see if we can bring them back. This is a simple version of what chemists call “chromatography”.
Things Required:
Red and blue food colouring
Medicine dropper
A small container
2 white napkins or paper towels
Newspaper
A cup of water
Directions:
Mix 2 to 3 drops each of red and blue food colouring in the same small container. Put the two napkins together and place them on top of the newspaper. Pour the coloured mixture in the centre of the napkins. With the medicine dropper, squirt water on the food colouring and try to separate the colours.
This Is What Happens:
The coloured mixture separates into purple (red-blue) and light blue areas.
Science Behind It:
The water acts as a solvent, dissolving the food colouring solution. Because the colours dissolve at different rates, they separate into circular coloured areas as the solvent travels through the absorbent, sponge-like napkins.
