This cabbage will turn blue |
Whatβs Happening? Red cabbage juice is sensitive to things which are acid or the opposite, alkali. If you add acid to the cabbage goes red. If you add an alkali and it goes blue. You can use this to test whether household substances are acid or alkaline. Conclusion: When you add the water to the cabbage leaves in Norfolk, it turns blue because Norfolk water is hard water β it is very alkaline. In Cornwall, for example, the water is acid and is known as soft water. There the cabbage water would stay red. If you added the vinegar first and then the bicarbonate of soda, you will have seen lots of fizzing. This is because the acid vinegar and the alkali bicarbonate react violently, giving off carbon dioxide. Go back to the start Β» | 
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