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Do a neutralisation

    Alginate strawberries

    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.