Materials:

• Red cabbage

• Alcohol 96º.

• Mortar

• Various colourless household substances: salfumán, lemon juice, vinegar, water, bicarbonate, ammonia, soda, soda pop, tonic, bleach...

• Vessels

• Scissors

• Strainer

Procedure:

1. Cut a couple of red cabbage leaves with scissors.

2. Put the pieces in a mortar and pestle and add alcohol.

3. Crush with the pestle and mortar until the alcohol is a deep purple colour.

4. Straining the solution

5. Place a small amount of the product to be measured in different beakers to measure its pH.

6. With a dropper or syringe add a small amount of cabbage extract.

7. Observe the new colour

8. Determine its pH by comparing the colour with the scale in picture 1.