<p> Make your own Acid-Base Indicator</p><p>Materials Equipment</p><p>½ small head of red cabbage (~ 100 g) Knife 2 L distilled water Blender or food processor 125 mL vinegar Sieve or colander 125 mL ammonia 1 L beaker 5 mL baking soda 7 250 mL beakers 125 mL club soda Spoon or stirring rod 5 mL laundry detergent (solid or liquid) Graduated cylinders, measuring spoons 125 mL milk</p><p>Procedure</p><p>1. Cut the red cabbage into 2.5 cm cubes. Place the cubes in the blender or food processor and adding enough water to cover the cabbage. Blend/process until the cabbage is chopped into even tiny pieces. Using the sieve, strain the liquid from the mixture into the 1 L beaker, pressing the cabbage to speed the straining. Discard the strained cabbage, keeping the cabbage extract. </p><p>2. Pour 125 mL of vinegar into one of the 250 mL beakers. Add about 5 mL of red cabbage extract and stir the mixture. Record the colour of the mixture. </p><p>3. Pour 125 mL of laundry ammonia into another 250 mL beaker. Add about 5 mL of red cabbage extract and stir the mixture. Record the colour of the mixture. </p><p>4. Place about 5 mL of baking soda in another beaker. Add 125 mL of distilled water and stir the mixture until the soda has dissolved. Add about 5 mL of red cabbage extract and stir the mixture. Record the colour of the mixture. </p><p>5. Dissolve about 5 mL of laundry detergent in 125 mL of distilled water. Add about 5 mL of red cabbage extract and stir the mixture. Record the colour of the mixture. </p><p>6. Pour 125 mL of milk into another 250 mL beaker. Add about 5 mL of red cabbage extract and stir the mixture. Record the colour of the mixture.</p><p>7. Test other household materials in a similar fashion. Solids and viscous liquids should be tested by dissolving them first in distilled water. Substances you might want to test include sugar, lemon juice, table salt, shampoo, antacid tablets, and aspirin or Tylenol. 8. When finished, the solutions may be discarded down the sink. Rinse with water. </p><p>Adapted from: Shakhashiri, B.Z. (1989). Chemical Demonstrations A Handbook for Teachers of Chemistry Volume 3. Madison, Wisconsin: The University of Wisconsin Press.</p>