Say what... Magazine : 1609
Kym Moore Assistant Editor PAG E 10 Say what... Digital Magazine • Issue 33 • September 2016 • • http://say what.nz diY ph-d... with K ids You Will Need: • Red Cabbage - you will use 3-5 leaves depending on the number of test pots. • Water • A sharp knife • A blender • A sieve • Abowl • Some clear cups for running tests (we had some beakers left over from a party) • Clean teaspoons for adding test materials • Test materials - you can try tap water, lemon juice, baking soda, vinegar, washing powder, citric acid, etc. Instructions I got my daughter to help with this. It wasn't time consuming but even in the preparation there was learning to be had. Into your blender add chopped red cabbage leaves and some water. You want about a cup full of water and roughly 2 cups of cabbage (four leaves seemed plenty). It's important that you add the water pre-blitz. Once you have your water and cabbage leaves in the blender, pulse the mixture until it is a pulpy purple smoothie. Remove the lid and pour the blender out over a sieve into a bowl. Squeeze as much of the cabbage juice out of the cabbage pulp. You can then use that pulp in your dinner or just add it to the compost. Now, pour a small amount of your red cabbage juice into each of your test cups. You can mark each one with what the test material will be. To add a bit more fun to the testing, you and your co-testers can take a guess at the colour your test substance might produce. Keep in mind the natural colour of the test sample as well. Before being blitzed the red cabbage has a rough pH of 4. But blitzed with water, the pH rises and could be around 6 or 7 - which is very close to neutral, a perfect benchmark to start from. Now in your various containers you can add some of your test materials. This will then change each cup a different colour and a different pH. We got a lovely forest green from baking soda. Citric acid made a strawberry red. We ran a little of the pulp under water and saw the deep purple colour turn a very pleasing blue. This is actually an indicator that the water has a pH of approximately 8 - slightly alkaline. My eldest daughter has taken a keen interest in chemistry recently. We were talking about things that are acidic and I mentioned litmus paper the other day. She wanted some but after a quick search online for a litmus paper retailer I realised I actually had everything I needed to test acidity at home. So we went to work together, creating a DIY pH-Detector solution.