Acids, alkalis and indicators

19th January 2023

This week, the Year 7s have been learning about acids, bases and indicators learning about the definitions, properties and examples both in the lab as well as in everyday life. They have defined acids as substances that turn a litmus strip and universal indicator paper red and alkalis as those that turn the colour of a litmus strip and universal indicator blue.

Mr Mulongo showing us how it is done

Since chemistry is not only confined to a lab, we decided to take our investigations to the kitchen and test a few household chemicals. We challenged ourselves by using our own simple preparation of an indicator. Can you guess what substance we used that can be found in a kitchen? Red cabbage! We grated some red cabbage and briefly boiled it to extract its dye. We then tested some chemical solutions within our reach to establish whether they are acids, neutral or alkalis.


Thrilling! Our school-made indicator had the same colour change as the earlier experiments that were conducted using commercial indicators. Orange juice and vinegar were confirmed as weak acids while hydrochloric and sulphuric acids as strong acids. Washing up soap, baking powder and ammonia solution showed properties of weak alkalis.


Bravo Year 7s, for your curiosity, exciting participation and confidence to begin applying knowledge in this topic!