To the thin layer of purple jelly, you can add drops of lemon juice, vinegar, sodium bicarbonate and ammonia (if supervised). Acids make the jelly turn from purple to pink and alkalis make it turn blue, green and even yellow. We used pipettes (or syringes) to add drops and the colour changes are reversible.
Adding sodium bicarbonate at acid on the jelly makes carbon dioxide bubbles and the colour changes were quite beautiful. Plus my kids were fascinated by the texture of the jelly and by using the pipettes to transfer liquids. You could photograph the mixtures and have a science-art project!
You need:
- plastic containers
- red cabbage
- gelatine
- lemon juice
- vinegar
- sodium bicarbonate dissolved in water
- (diluted ammonia - small group supervised activity)
- pipettes or syringes
- containers for the lemon juice, vinegar and sodium bicarbonate
