Here’s what you’ll need:
- Red cabbage
- Boiling water (ask a grown up to get this for you)
- A sieve
- Clear jug
- Bicarbonate of soda
- Clear glasses
- Rip up some red cabbage leaves into small pieces and put them into a bowl
- Ask a grown-up to pour some boiling water onto the cabbage leaves so they’re covered. Leave it to cool for 20 minutes
- Drain off the cabbage juice by pouring it through a sieve into another bowl
- Next, put the cabbage juice into a clear jug and stir in a level teaspoon of bicarbonate of soda – this should make the liquid a bright blue colour! (if it looks more purple than blue, add a bit more bicarbonate of soda and stir it again)
- Finally, place the jug in the fridge for 40 minutes
- Now, fill a clear glass with some lemonade about half way and top it up with a small amount of your bicarbonate of soda mixture from the fridge and watch it turn into a pinky-purple fizzy drink!
The science behind it: The cabbage has a special pigment in it (an anthocyanin) that changes colour depending on how acid or alkaline something is. Bicarbonate of soda makes the mixture alkaline – and blue – but the acidity in the lemon-based drink turns it pink. Pretty clever, right?
Send us a clip of your finished experiment to firstname.lastname@example.org by Friday 14th March for a chance to win a free science kit!