Today daughter and I had great fun (her brothers watched eagerly from the sidelines) testing for the presence of acids in various items. One of the books that we've been using is Usborne Science in the Kitchen, which is what guided us today.
We started out by cutting up some red cabbage and boiling it in a saucepan full of water. After it cooled (while we were gone for piano lessons ;-) , then we strained it, poured it into several plastic cups and added various liquids to see if they were acids or not. If the cabbage water stays the same deep blue color, then there is no acid present. Any color change, especially to red or purple, indicates the presence of an acid.
Do you want to see our results? Well, Okay -
From left to right, we tested: red wine vinegar, rice vinegar, milk, fresh lemon juice, plain natural yogurt, soda pop, salt and sugar. (The salt cup is behind the soda and sugar cups.)
It was Very Cool watching the colors change before our eyes, and to see the different shades indicating more or less acids. The milk hardly changed at all, the salt and sugar stayed just the same. The lemon juice was the most extreme reaction, along with the vinegars. The yogurt was interesting - I didn't think it would change that much, and the cola changed slightly to a deep muave-ish-purple.
We are enjoying science so much that we may just do Sonlight Science next year, too. The best part of it is watching the great Discover & Do DVD that is made just for Sonlight (in John & Sarita's kitchen, no less!!) Each DVD segment demonstrates the little lessons being taught in the Usborne Science books (Science in the Kitchen, Science with Plants, and Science with Air). Sometimes we just put the DVD in and we all watch it just for fun!