This experiment takes a little prep but it’s totally worth it.
Kitchen towel/coffee filter paper
Empty 2 litre bottle
Stove top/hot plate
- First you need to prepare your litmus strips.
- Grate a red cabbage.
- Boil the cabbage in 2 cups of water for 30 minutes.
- Strain the cabbage and KEEP the liquid.
- Let this liquid cool down.
- Once cool, dip in paper towel or coffee filter paper into the cabbage juice then let the towel dry out.
- Once the towel is dry cut into stripes about 20mmX60mm.
What you have made is a litmus tester. This is able to measure how acidic something is. If it goes a pinky red colour the substance is a acid if it goes green/ blue it is an Alkaline, also referred to as base.
So, is the juice of a Kiwi Fruit an Acid or a base?
What about other materials around us? Try Lemon juice, Vinegar. Milk, soap … the list is endless.
It’s also fun to pour the red cabbage juice into other liquids. Try pouring it into a little bit of vinegar.
The juice can be stored in a old drink bottle for about a week. You can dilute it down with boiled (but cooled) water to make it go further. How much you can dilute it depends on how good your cabbage is. We find a 50/50 mix works well.
Do take care when using chemicals. Even something like Kiwi Fruit juice can hurt you if you get it in your eyes. But we love a bit of danger here at Science in a Van.