Red cabbage indicator to classify liquids into acids and bases
An indicator reveals if a substance is acidic or basic. In solutions, acidic components release hydrogen ions, while basic ones release hydroxide (OH−) ions. The indicator changes color according to the solution’s nature.
• Red cabbage
• Knife (Use only under adult supervision; preferably let the adult do the chopping)
• Clear cups or glasses
• Household liquids to test
Prepare the Red Cabbage Juice
1. Ask an adult or someone who is supervising to chop up the head of a red cabbage into small pieces. About 2 cups of chopped cabbage should be enough for this experiment.
2. Blend the chopped red cabbage in a blender on the highest setting, along with just enough water to blend the chopped pieces into a smooth paste.
3. Pour the liquid through a strainer to filter out the red cabbage pulp.
Prepare Household Liquids
4. Decide which liquids you would like to test. Pour each one into its own glass, leaving enough room for the cabbage juice. You can try lemon juice, tap water, soapy water, milk, and baking soda/water solution.
Conduct the Red Cabbage pH Experiment
5. Using a dropper, pour a little bit of red cabbage juice indicator into the first glass. Watch the color change. Observe and record your results.
6. Continue until there is cabbage juice in all the glasses. You may need to use a spoon to stir the solution if the cabbage juice is not mixing with the household liquid. Add more cabbage juice indicator if necessary.