Wednesday, May 9, 2012

Kiwi Litmus Test


This experiment takes a little prep but it’s totally worth it.

You will need:
A large red cabbage
Kiwi fruit
Mixing bowl
Saucepan
Kitchen towel/coffee filter paper
Knife
Empty 2 litre bottle
Stove top/hot plate 
  1. First you need to prepare your litmus strips.
  2. Grate a red cabbage.
  3. Boil the cabbage in 2 cups of water for 30 minutes.  
  4. Strain the cabbage and KEEP the liquid.
  5. Let this liquid cool down.
  6. Once cool, dip in paper towel or coffee filter paper into the cabbage juice then let the towel dry out.
  7. 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.  

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