How To Make A pH Indicator With Cabbage

Acids, like citric acids in citrus fruits, tend to be sour in taste while bases, like baking soda, tend have a bitter taste. But of course you can't taste everything to test if it's an acid! In school you may have used litmus paper to determine if a substance was an acid or a base. In this simple science experiment, you can make your own pH indicator, which tests to see if solutions are acidic or basic.

Step 1

Grate about 1/2 cup of red cabbage. It might help to first cut the red cabbage into quarters so it's easier to grate.

Step 2

Put the red cabbage in a bowl and add just enough water to cover it.

Step 3

Crush the cabbage with the wooden spoon to produce a purple cabbage juice.

Step 4

Sieve the cabbage juice into several small cups. This is your pH indicator solution.

Step 5

To determine the pH of the soap, vinegar, or an unknown substance, just add it to the cups. An acid will turn the solution pink, and a base will turn the solution blue.