How To: Make a cabbage indicator

Join the A-TV science superstars and find out how to make a cabbage indicator to determine whether a substance is an acid or alkali.

To make your own cabbage test, you'll need the following materials:

red cabbage
boiling pot of water
strainer
small clear cups
medicine dropper
baking soda
clear vinegar
sprite
knife

1. Have your adult helper slice your cabbage into 6 sections. Put the cabbage in your bowl and then have an adult help you cover it with hot water. Let the cabbage steep in the hot water until the water has cooled and changed to a deep purple color.

2. While our cabbage cools, let's move on to the next step! What you need to do is dissolve some baking soda in some water. Take one of your cups and Add ½ cup water and 2 tablespoons baking soda to it then stir everything up really well. The next step is to pour some vinegar into one of the small glasses. Add about ½ cup. Take some clear soda and pour some of it into another small glass.

3. Now that the cabbage water is cold, strain it and put it into a beaker. This is your cabbage indicator. If you don't have a beaker at home, you can use a clear glass or jar. Now, pour ½ cup of the cabbage indicator water into an empty glass. Now that you have all of your liquids measured out in front of you it's time to see which liquids will change the color of the cabbage indicator!

4. Pour a little of the vinegar into the Indicator and see what color it changes to. It should look pink. You can change the cabbage indicator back to purple again by pouring some of the baking soda solution into it. Try the soda next. The acids in the vinegar turned the cabbage indicator pink and when you added the baking soda, it turned the indicator purple, because baking soda is an alkali.