Issue 95 is out now
Melissa Corkhill

By Melissa Corkhill

11th March 2009

Did you know that cabbage can be used to test the acidity or alkalinity of other substances, in a similar way to litmus paper? Today as part of National Science Week we find out how to create acid-alkaline indicator, using the humble red cabbage.

Melissa Corkhill

By Melissa Corkhill

11th March 2009

Melissa Corkhill

By Melissa Corkhill

11th March 2009

What you need:
Pickled red cabbage
vinegar
Bicarbonate of soda
at least three containers, such as small glass jars or even test tubes

What to do:
• Remove the cabbage from the jar as you only need the fluid that was in the jar. Put aside for your Dad to eat later.

• Pour a little of the cabbage juice into each of your containers. Note the colour of the juice. Put one container with the juice in to one side.

• In another container add a small pinch of bicarbonate of soda to the juice. What happens?

• To a different container add a small amount of vinegar to the juice. What happens?

Why it works:
The colouring in the cabbage juice is an acid/alkaline indicator. When it is in an acid, such as vinegar, the juice turns red. When it is in an alkaline, such as bicarbonate of soda in turns blue-green. Are there any other substances that you could test? You could try lemon juice, washing up liquid and soap flakes, for example.

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