Indicators

Red cabbage juice solution works well instead of universal indicator solution.

Making Cabbage Indicator

Acid base indicators are chemicals that change colour in the presence of different pH levels. These are usually larger organic molecules. Some, like that in purple cabbage, are natural.

You will be making an acid base indicator from purple cabbage. This indicator is a very good one with good color changes.

Materials Needed:

1. Tea strainer
2. 2 Glass quart jars with lids
3. 1 Quart distilled water
4. Uncooked purple cabbage
5. Hotplate and pan

Procedure:

1. Fill one jar with cabbage leaves that have been crushed into small pieces.
2. Heat the distilled water to boiling, and fill the jar containing the pieces of cabbage with the hot water.
3. Allow the jar to stand until the water cools to room temperature.
4. Poor the cooled cabbage solution through the tea strainer into the second quart jars. Discard the cabbage leaves.
5. Store the cabbage indicator in a cool place until needed.

Results:

1. The hot water dissolved the colored chemicals in the cabbage.
2. These colored chemicals turn red when mixed with an acid, and green when mixed with a base.
3. This indicator can be used to test for the presence of either an acid or a base.