Acid or alkaline?
Girls discover how grape juice turns red when mixed with acid, and green when mixed with an alkaline.
- Pour an equal amount of grape juice into two clear plastic cups.
- Add some lemon juice to one and watch it turn red.
- Add some baking soda to the other cup and watch it turn green.
- Ask the group to explain what has happened. You may need to tell them that the grape juice is an indicator, which turns red when mixed with an acid and green when mixed with something alkaline.
- Divide the unit into smaller groups and allow them to choose the substances they will test for acidity or alkalinity. They should test each substance with the grape juice and record their findings.
- As a group, discuss their experiments. Did they all get the same results?
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