Making a lava lamp

To start with, we talked about the properties of water and oil and then we thought about food colouring. In groups we added water and then oil and waited for it to separate. We then added the food colouring and again waited. The food colouring slowly dropped to the bottom. We then added an aspro clear tablet and the results were dramatic. The aspro clear contains baking soda and citric
acid.  A chemical reaction occurs and carbon dioxide is formed. Bubbles of gas rise up through the oil making colourful bubbles.