Experiments provided by Dr Audrey Matthews, Department of Applied Science, De Montfort University

Simple ingredients for this experiment

1. What you need
Empty washing-up liquid bottle, vegetable oil, water, washing up liquid, food colouring.

Dr Audrey Matthews making her own glitter shaker

2. What to do
Fill the bottle with a quarter of water and a quarter of oil. Add food colouring and shake. Add a squeeze of washing up liquid and shake. Write down what you observe at each step. Add glitter if you want to. Screw on the lid.

At sea, detergents are added to disperse oil slicks

3. What’s happening?
The oil floats on the water as it is not as dense. The food colouring should mix with the water layer and stay there even after shaking. This is because the food colouring is chemically more like water rather than oil. When washing up liquid is added and shaken it forms a stable emulsion that is a suspension of oil globules in the water. A similar method is used to disperse oil slicks at sea.

Want to investigate some more?
Try this experiment out with other food colourings and layers of different oils.