Magical Colour-Changing Potions

Materials
  • Half a red cabbage
  • Glass jars, milk bottles or cups (your choice really, anything you can see through)
  • Stirring stick
  • Bicarb soda (baking soda)
  • Vinegar
  • Lemon juice
  • Cream of tartar
  • Water
  • Dishwashing liquid
  •  Pen and paper (for labels)
Procedure
- Boil cabbage (chopped) in a medium saucepan with water covering it until most of the colour has been extracted from the cabbage. Strain and move liquid to a large bowl or jar to cool. I kept ours sealed in a jar until we were ready to use it the next day.
- Pour some of the purple water into a glass of your choice and try adding different ingredients and combinations to see the chemical reactions between the alkalising and acidic ingredients. (Colour combinations listed at the bottom) If your purple water is too dark, you can add some more plain water to lighten it, the colour will still change.
-After each lot, pour it into a separate glass and keep a label of which ingredients created the result. Rinse and repeat each time with your mixing glass. Once you are done you can compare your colour change results.

-Once you are done, it's time for some potion fun! You can use a small amount of the leftover purple cabbage water in a glass, add some vinegar, a small amount of dishwashing liquid and give it a stir. Next add some bicarb soda and watch the colour changing potions fizz up and out of the glass!
Colours will vary on how much of each ingredient is added.
Teal - Bi carb soda
Blue - Lemon juice and vinegar
Purple (changes and returns to its original colour) - Lemon juice THEN cream of tartar
Magenta - Lemon juice and bi carb soda
Pink (with slight purple) - Lemon juice, vinegar and cream of tartar
Sunset pink (more peachy tone) - Lemon juice
This experiment is a lot of fun, showing children how to extract natural colouring from a vegetable, the red cabbage's ability to act as a pH indicator and learning about alkalising and acidic ingredients.