🥬 The Magic of Red Cabbage: A Natural pH Indicator

Materials

• ½ head of red cabbage

• Hot water

• Blender or pot & strainer

• Clear cups or glasses

• Substances to test: vinegar, baking soda solution, lemon juice, soap water, soda, milk, etc.

  Steps

  1. Make the cabbage indicator: Chop the cabbage and blend it with hot water. Let it sit for 10 minutes, then strain to keep the purple liquid—this is your pH indicator.

  2. Pour into cups: Fill small amounts of the cabbage juice into separate clear cups.

  3. Add test substances: Add a small amount of each household liquid to its own cup of cabbage juice and observe the color change.

  4. Record results: Make a color chart from acidic (reddish) to basic (greenish/yellow).

     What’s Happening?
     Red cabbage contains anthocyanins, pigments that change color depending on pH.

     • Acids (like lemon juice or vinegar) turn the solution pink/red.

     • Bases (like baking soda or soap) turn it green or yellow.

     • Neutral substances may leave it purple.

       Applications

       • Red cabbage indicators are a great teaching tool in classrooms.

       • Scientists use synthetic indicators like litmus or phenolphthalein for precise measurements.

       • Natural indicators are eco-friendly alternatives for introductory chemistry.

       Safety Tips

     • Handle hot water carefully when preparing the cabbage extract.

     • Some substances may cause skin irritation—use gloves if needed.

     • Don’t taste-test the mixtures, even if they’re made from kitchen items.