This time we were looking at acids and alkalis and indicators.
I spent a few days making home made indicator paper - totally the wrong time of year for red cabbage so I used blackberries instead and extracted the colour using alcohol.
I also decided to try out turmeric which gives a vivid blood red colour in alkali
this worked really well but was quite smelly so everything was done outside!
We started the session by looking at our giant test tubes and using universal indicator liquid.
We used this as a visual aid throughout the session to remind everyone
We then used homemade berry paper to test and sort a range of liquids.
We tested cola, lemonade, washing soda, bicarbonate of soda, milk and citric acid.
We added about 3 ml to each well in our dimple dish and dipped in the paper. The berry paper needed about 5 seconds to soak up the liquid and change colour. Sometimes the colour change was only faint but other liquids gave a strong change
Once we had got some idea of which were acid and which were alkali the children had to choose their best alkali to test with the turmeric paper.
Some wondered what would happen if they then dipped it into an acid - it changed back to yellow!
Finally we used universal indicator papers to give a much more sensitive and very colourful result.
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| what a great montage by the class teacher! |
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