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The acid test

Do you know that you can make your own acidity test from cabbage?! This is one of our favourite experiments to do at Tūhura Science Centre at Otago Museum. Here is how you can do it at home!


  • Red cabbage
  • Water
  • Vinegar
  • Baking Soda
  • Foods to test


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Take four large red cabbage leaves and boil them in water for approximately 10 minutes until the water is a purple colour. Wait until the water has cooled down, discard (or eat!) the leaves and pour the water into a jug.

Now take two clear glasses. Put vinegar in one and baking soda (around a teaspoon) mixed with water in the other. Take a couple of spoonfuls of the cabbage water and add them to each of the glasses.

The acidic (vinegar) glass will go pink, and the basic (baking soda) glass will go blue. Use the pH scale to help you test other food too. What colour does your sandwich go? What about biscuits? You can test your whole lunchbox. Frank is getting ready to test some grapes in this picture!

You can film yourself doing this experiment and share it with us by tagging us at @otagomuseum. 

We would love to see how your lunch tested!
Frank is getting ready to test some grapes!



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