Activities & Days Out / 25 April, 2018 / Nanny Anita

Kitchen Science: Red Cabbage Indicator Experiment

Do you know what my first thought was when doing this red cabbage indicator experiment? Why is called red cabbage when it looks purple? Yes these are the sort of questions that I constantly think off. Anyway I have been trying to do more science experiments with EC. As it turned out they actually had some friends come over for ice cream so they all got involved in doing it.

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You will need:

• Red cabbage
• Blender
• Water
• Sieve
• Glasses
• Pipettes
• A range of house hold liquids like:  vinegar, bicarbonate of soda, Coke, lemon, egg whites, washing detergent*, Dettol*

*If you have younger children you may either want to skip these or do these ones yourself.

Start by tearing off some cabbage and adding it with some water to a blender. Blend it for a couple of minutes.  When it’s ready strain the mix through a sieve to get rid of all the bits of cabbage. Please note that this really does stink, so doing it outside helps get rid of the smell.

Pour the cabbage solution into some glasses.  Clear glasses are best for this part so you can really see the the reactions happening.  You will need as many glasses as liquids you are testing out.

In another set of cups set up you liquids you are testing.

Carefully add each of the solutions to the red cabbage solution. Please be careful not to mix chemicals though, especially if you do use cleaning supplies.

As you add the liquids to the red cabbage you should see the solutions start to change colour.

We used the pH strips that we have for the fish tank to have a look at there pH rating of each solution at the end.

YC and her friends (unfortunately EC had an appointment that we had forgotten about) were absolutely in awe of what was happening. They thought it was some sort of Harry Potter potions class going on. We kept everything on the table to show EC when he had finished. Promising him that I would definitely do it again with him.

The science behind the Red Cabbage Indicator Experiment

Red cabbage contains a pigment molecule called flavin, which is a natural pH indicator that changes colours according to the acidity of the solution. Purple carrots, apple skin, plums, poppies, cornflowers, and grapes all have this anthocyanin molecule in as well.

Depending on the acidity of the solution the red cabbage will either turn a red colour, or if it is more alkaline it will turn yellow/ green. As you can get such an array of colour it possible to therefore tell what the pH of the solution is.

If you enjoyed doing this red cabbage Indicator experiment be sure to check out some other of my kitchen science activities like magic milk, skittles experiment, Diet Coke and mentos, making plastic, and walking water experiment.

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