Red Cabbage Indicator

You will need

  • 1 Sauce pan
  • 1 Chopping board
  • 1 Knife
  • 1 large glass jar
  • 4 small glass jars
  • 1 Red Cabbage
  • Vinegar, lemon juice, water and bicarbonate of soda to test

What to do

  1. Carefully chop the red cabbage leaves into small pieces on the chopping board.
  2. Put the red cabbage in a sauce pan and add water until the red cabbage leaves are completely covered.
  3. Gently boil the red cabbage for 10 to 15 minutes.
  4. After the sauce pan has cooled down, collect the water in a large jar.
  5. To better see the red cabbage water’s colour add some water to dilute it.
  6. Transfer the red cabbage water into the 4 small jars.
  7. Add a dash of vinegar to the first small jar with red cabbage juice and observe what happens.
  8. Repeat step 7 for the other substances you want to test. Each substance goes into a new small jar with red cabbage juice.
  9. What colour changes do you observe?

Background

Red cabbage juice is a pH indicator. This means it changes colour depending on if it is in an acidic, alkaline or neutral environment. In this experiment you are testing some acids (vinegar and lemon juice), some alkalis (bicarbonate of soda) and a neutral substance (water).

Which colour changes can you observe in your experiment? What colour does red cabbage indicator have in acids, bases or with neutral substances?

You can watch this experiment as a video here:

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