red cabbage as an indicator

First we cut up a large cabbage and soaked it in boiling water. This dyed the water purple. We then got a cotton sheet cut up into smaller pieces and put them into the water. The material was dyed purple. After it dried we experimented using various acids and alkalis.  

Red cabbabe is an indicator and it indicates whether a substance is an acid or an alkali. Acids will turn the material pink while alkalis will turn the material green. Acids we used were malt vinegar, distilled vinegar and lemon juice. Alkalis we used were bread soda solution and soap. 

We learned that alkalis are a chemical opposite to acids. We have acid in our stomach called gastric acid, this breaks down our food.  

The first time we did the experiment we did not use 100% cotton therefore the colours were very faint. The next time we did the experiment we used 100% cotton and the colours were very bright.