Saturday, 11 February 2017

Testing for Acids and Alkali with cabbage water indicator


Red cabbage water indicator experiment to test for acids and bases / alkali, with printable instructions and results worksheets from a muslim home school
When I think to my chemistry lessons back in school, I don't have too many fond memories. Chemistry was probably my least favourite subject back then. The only thing I can really remember is something about Bunsen burners and waiting for the bell to ring at the end of class!
20 years later, here I am teaching my own children; I now look at chemistry with a whole new vision, and I think it is pretty cool.
This is one of the perks to home education Alhamdulillah, I am getting a brand new learning experience myself. I sometimes think how ignorant would I be if I wasn't home schooling?

Anyway, here is an easy chemistry experiment we did as part of our home school science club. You can do this at the kitchen table inshaAllah....no Bunsen burner required! 

Get ready to make your own red cabbage indicator that will test the acidity or alkalinity of various liquids inshaAllah.

What you need
Red cabbage water indicator experiment to test for acids and bases / alkali from a muslim home school
·        10 small clear plastic cups
·       10 different liquids to test
(ie: washing up liquid, white vinegar, cola, bleach, milk, baking soda (dissolved in water), black coffee, water, shampoo, lemon juice)
·       Red cabbage
·       Large glass jug or bowl.

Instructions

Safety First....Some of the liquids you will be testing might burn your skin or hurt your eyes, such as the bleach and soap. Be careful if you are handling these

   To prepare the cabbage water indicator:

Chop up red cabbage and put into a large glass jug or bowl
Pour boiled hot water over it (with adult supervision). Leave until it has cooled.
strain the red cabbage to seperate the liquid to make red cabbage water pH indicator
Once the liquid has cooled, strain the cabbage to separate the cabbage water.
You will have a dark purple liquid. This is your indicator ready to use.

Now you can use the indicator to test the acidity or alkalinity of various liquids. You should see that acids will turn pink-redish, and alkalis will become green-blue.

range of acids and alkali being tested in red cabbage water pH indicator

I think the colour change is more dramatic when you fill the cups with the red cabbage indicator first then add each liquid you are testing, rather than the other way around. Its nice to see the purple cabbage water indicator change colour when each liquid is added to it.

adding white vinegar to red caggabe water indicator changes colour
I prepared a basic introduction information sheet which was given out in the home school class together with experiment instructions and results sheet to record observations. You can download this by clicking on the highlighted text below:
printable red cabbage water pH indicator experiment instruction sheet and results chart

With the left over cabbage water, you can make cabbage paper to test for acids or bases. Just dip a coffee filter into the cabbage water and leave to dry.
Once dry you can wipe a little food or liquid drops onto the paper. You should find the colour of the paper will change in the same way as the liquid cabbage water above.
We haven't completed this test yet, but will update with a picture once we have inshaAllah.
making red cabbage pH paper

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