Shake the bottle and it turns blue. Leave it and the blue colour disappears.
Ingredients and equipment that you will need
Bottle
Washing soda
Fructose (fruit sugar)
Hot water
Methylene blue
Method and further information
Put one teaspoonful of washing soda and two teaspoonfuls of fructose (fruit sugar) in a bottle with 200 mls of hot water. Add a drop of methylene blue (which you can get from pet shops or aquarium supplies). When it goes colourless, shake the bottle.
This mixture reacts with oxygen in the air and goes blue. There is air inside the bottle which mixes with the liquid when you shake it.
Be careful – you should ask an adult to help you with these experiments. Do your experiments in old yoghurt pots, jam jars or bottle tops. Don’t use cups or glasses in case someone thinks it’s a drink.