Megan Auer, our brilliant science teacher, has just shared this chemistry experiment using cabbage juice. If you know where to find a cabbage, join us in the fun of repeating this experiment at home, with the help of your young learners. The experiment allows you to visually indicate whether common household solutions have basic or acidic pH.
Prepare Cabbage Juice
Red cabbage juice naturally contains a pigment anthocyanin, that changes color in different pH solutions. Take about three leaves of red cabbage, and thoroughly blend with about 3 cups of tap water. Screen the pulpy concoction through a cheese cloth and set aside. This is your indicator solution, with a natural color that is purple. Prepare a few plastic cups in which you will be mixing cabbage juice with the test substances.
Invite your middle school child to find a few common household edible items that s/he wants to evaluate for pH. These items are your test substances. At our 8th grade chemistry class, Miss Auer was presented with the following list:
It is easy to surmise that lemon juice is likely to be very acidic, but what about tooth paste or soda drinks? Now is the time to start the experiment and see for yourself.
Place your test substances into the cabbage juice, just about a tea spoon per half cup. Stir if your substance is not liquid (like the toothpaste). Use as many cups of cabbage juice as you need, and label them. Keep one cup filled just with the plain cabbage juice, for easy comparison.
Observe Your Findings
The mixed solutions change color instantly. Pink liquids indicate presence of acid; blue-greens indicate basic pH. Neutral solution remains purple (if you started with the red leaf cabbage, like our teacher Ms. Auer did).
Draw your conclusions – we know that our teeth might suffer from acidic drinks or foods. Which of your concoctions indicate elevated acidity? Do two different toothpaste test differently? Have fun getting a closer look into the chemical composition of common food stuffs.