Today on the blog, I have the most exciting thing you can do with a cabbage. It's also a project taken from my new book - 101 Things For Kids To Do On A Rainy Day.
You Will Need:
Boiling water (grown ups to use)
This is a great trick to freak out your friends and family - plus you can have lots of fizzy drinks because they will ask you to show you this trick again and again. And if that's not enough to make you love science I don't know what will.
First you need to make some coloured cabbage water. Rip up a couple of red cabbage leaves into small pieces, put these in a bowl and ask a grown up to pour on some boiling water so the leaves are just covered. Leave it to cool for 20 minutes then drain off the juice by pouring it through a sieve into another bowl.
Now put the liquid 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 still looks a little purple, add more bicarbonate of soda and stir again. Finally place it in the fridge to chill for half an hour or so.
Now, to freak out your friends...
All you need to do is pour them some lemonade into a clear glass before offering to top it up with your 'magic colour changer'. Now with as much dramatic flair as you can muster, pour just a very small amount of your blue liquid into the fizzy drink and watch it turn... pink!
Picture copyright: Kyle Books/Rachel Warne
If you want to reveal to them how it works, explain that 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 or lime based drink turns it pink.
Then again you could explain nothing... and keep freaking them out. That sounds like a much better plan if you ask me.
Tip: For an even stronger colour you can mix a quarter teaspoon of citric acid into the lemonade - just make sure you stir it well until it's completely dissolved.
I even have a video if you want to see the magic 'in action'.