Cabbage Science: Something Fun to do on a Snow Day!

Cabbage Science

Test Whether a Substance is an Acid or a Base

Objective:

Make your own pH indicator and use it to test the pH of various household solutions.

How do you tell if something is an acid or a base? You use a chemical called an indicator, which changes in color depending on whether a solution is acidic or basic. (Specifically, an indicator works by responding to the levels of hydrogen ions in a solution.) Red cabbage contains an indicator pigment molecule. Very acidic solutions will turn a red color. Neutral solutions result in a purplish color. Basic solutions make a greenish-yellow or yellow color.

Materials:

Purple cabbage

Medium pot

Water

Vinegar

Liquid soap

Baking soda

Clorox (for younger kids, use lemon juice instead)

4 jars or test tubes

Procedure: Place leaves of a purple cabbage in a pot and boil it in water. When the liquid turns purple, let it cool. 

Pour the purple liquid in four jars or test tubes. Predict whether the color of the liquid will change after adding the substance and what color it will be.

Pretty cool, right?