Alginate strawberries

Do a neutralisation

An experiment to show acids and alkalines as different colours.

Ingredients and equipment that you will need

Red cabbage indicator – see Make an Indicator
An acid – vinegar or lemon juice
An alkali – Soda crystals, available at any supermarket, work well

Method and further information

Pour some indicator into a jar and add a spoonful of acid. The indicator will go pink.

Now add alkali a little at a time and it will go back to purple. Add too much alkali and it will go green, then you can neutralise it again with some acid.

Be careful – you should ask an adult to help you with these experiments. Do your experiments in old yoghurt pots, jam jars or bottle tops. Don’t use cups or glasses in case someone thinks it’s a drink.