My family recently visited one of our favorite science museums, and my kids got to do a very cool hands-on experiment with red cabbage that I couldn't wait to tell you about. After my last time writing about red cabbage (the time I accidentally made fart paint), I thought this was a good way to redeem one of my favorite vegetables.
This experiment would be fun to do with kids of any age. My 4-year old has no idea what pH means, but it didn't stop her from having fun using a medicine dropper. So, if your kid has the dexterity to work a dropper, they would likely enjoy it.
Here's the basic gist:
- Cut up about 1/4 red cabbage, and boil it in a few cups of water. Pull out the cabbage and reserve the cabbage water. Let it cool and pour into a container. It will be purple.
- Gather a few things from your house that are acidic, basic, or neutral. (Within reason, don't choose anything unsafe!) Here are a few ideas: aspirin, baking soda, detergent powder, lemon juice, vinegar, ammonia, sugar, salt. Write the name of each substance down on a piece of paper.
- Have kids scoop a small amount (like, 1/4 - 1/2 teaspoon) of each of the gathered substances into small bowls or ramekins. A plastic paint tray would work really well. Make sure you label which substance is which!
- Using a medicine dropper or pipette, put a dropper-full of cabbage water on the substance. What color does it turn? Record the color results on your paper listing all the substances you are trying.
- Interpret your results. If it stays the same (purple), your substance is pH neutral. If it turns pink, it's an acid. If it turns blue, it's a base. The stronger the color, the higher (or lower) the pH of the substance.
As I said, we did this experiment at a museum, but it would be a great hands-on activity for studying pH, or to use up some questionable cabbage. This activity is also mentioned in GrowLab: Activities, along with more discussion on plant acids, and the effects of acid rain. Check it out if you want to dive deeper on pH!