Jayman and Missy wondered what on earth I was doing when I began pulling armfuls of things out of the fridge, as well as loads of cleaning supplies from beneath the sink. Has Mama finally gone nuts? Nope, Mama is getting ready for a fun afternoon of acids and bases for kids.
This easy, inexpensive activity of acids and bases for kids is based on a lab experiment I did with my college students several years ago. Teaching acids and bases was always one of my favorite units because of this very experiment. It's so simple and colorful, yet so powerful.
We began our acids and bases for kids by having a brief review of basic pH. We've had a few fun chemistry experiments for kids in the past that have dealt with acids and bases—and to my surprise, the kids remembered. So without much further ado, we began the current experiment of acids and bases for kids.
The idea is simple. Mama made a liquid pH indicator. That is a material that changes color when something is added to it, depending on how acidic or basic the added substance is. We used red cabbage water, since it is so cheap and easy to make. Here's how to do it:
Bring 2 cups of water to a steady boil in a heavy saucepan. Remove pan from heat and immediately add 2 cups of chopped red cabbage. Allow to steep for 10 minutes. Drain off and reserve the purple liquid.
It's important to use the pH indicator at room temperature, since pH is partly dependent on temperature. It helps if all the test substances are at room temperature too, so we let them sit at room temperature for a few minutes while the cabbage indicator cooled completely.
Our experiment of acids and bases for kids is quite simple: just mix equal parts of the cabbage water and the test substance and record a color change. We used 1.5 ounces of each liquid. Warm colors (red, yellow, pink) indicate an acidic substance. Cool colors (green, blue, light purple) indicate a basic substance. If the cabbage indicator doesn't change colors at all, the test substance is essentially neutral.
From left to right, top row: plain cabbage indicator; indicator plus lemon juice; indicator plus ammonia; indicator plus Tums. Bottom row: indicator plus Diet Coke; indicator plus dissolved dish soap; indicator plus lemonade; indicator plus lemonade plus Tums.
The most fun part was letting the kids guess whether something would be acidic or basic. They were surprised by the dish soap (which we used by dissolving a little bit of dish soap in some water) and the Febreeze, but they guessed right on about the pickles and lemonade.
Jayman, who has decided he wants to be a scientist when he grows up, surprised me most of all. We'd just finished the last of our fun chemistry experiments for kids when we mixed lemonade into the indicator and saw a great pink color. "Hmmm, what happens if we add one of the Tums tablets in there?" Jayman asked.
I was stunned. We'd already determined that Tums were basic. Had Jayman put that together? I don't know, but we went ahead and added a Tums tablet to the acidic mixture. As we all watched in fascination, the color slowly changed from acidic pink to more neutral light purple. We'd just simulated what happens when a person with heartburn (too much acid) takes a basic Tums and neutralizes some of the acid.
We all really enjoyed our acids and bases for kids. In fact, it was so fun that I had to stop partway through and make more pH indicator so we could test more acids and bases. Quite a fun and colorful afternoon.
Come join my class at Mama University!