Red Cabbage pH Indicator

Project Overview: Red cabbage is hiding a secret superpower: its juice changes color depending on how acidic or basic a substance is. This project turns an ordinary vegetable into a real chemical pH indicator, the same tool chemists use in labs, just made entirely from something you'd find in a grocery store.

Materials Required: 

1. One-quarter head of red cabbage

2. Hot water

3. A blender or knife (to chop the cabbage finely)

4. A strainer

5. 5 - 6 clear cups

6. Household liquids to test: vinegar, baking soda solution, lemon juice, soapy water, clear soda

Instructions: 

1. Chop or blend the cabbage into small pieces and place it in a heat-safe bowl.

2. Pour hot water over the cabbage until covered, then let it steep for 10 minutes as the water turns a deep purple.

3. Strain out the cabbage pieces, keeping the purple liquid; this is your indicator.

4. Pour a small amount of the purple liquid into each of your clear cups.

5. Add a small amount of household liquid to each cup and observe the color change: pink/red indicates a strong acid, purple stays neutral, and blue or green indicates a base. Record your results and rank the substances from most acidic to most basic.

Congratulations, you just built your own working chemistry indicator.