- A clear plastic bottle or jar
- A bottle of vegetable oil
- Water
- Alka Seltzer
- Food colouring (a spooky colour )
- Fill the bottle or jar a quarter full with water.
- Top up to the (near) top with the vegetable oil
- The oil and water should separate into two layers, water at the bottom and oil sitting on top. Add about 6-8 drops of food colouring once they have separated.
- Pop in half an alka seltzer tablet and watch the bubbles form.
Conclusion
As the alka seltzer is added (this is made of citric acid and sodium bicarbonate) it reacts with the water and form carbon dioxide gas and Sodium citrate. It is the carbon dioxide bubbles that carry the coloured water to the top.