A few weeks ago, Roy tried out an experiment with red cabbage. He added all sorts of household products to the concentrated juice of red cabbage to see what colours the cabbage turned. Some went a range of reds and pinks, showing they were acids, while others went blues, greens and yellows, showing they were bases. The kids were amazed at the changes in colour, and Roy thought it might be fun to show the experiment in reverse. So, he arranged a set of cups with clear liquid, and added a few drops the vibrantly purple red cabbage juice to them to see what would happen, thus inventing ‘Roys Magic, Colour Changing Drops’ as the children called them. He thought he would share how to do this with his online friends so they too could shock and amaze their family and friends.
You Will Need:
- Red cabbage juice. To see Roys instructions on turning red cabbage into red cabbage juice, visit his earlier post by clicking here.
- An old eye dropper or teaspoon
- A variety of clear liquids. Roy used:
- Citric acid, dissolved in water
- Bicarbonate soda, dissolved in water
- Tartaric acid, dissolved in water
- White vinegar
- Soap, dissolved in water
- Dishwashing powder, dissolved in water
- Clothes washing powder, dissolved in water
- Cloudy ammonia (if you use this, you will need an adult to help)
- First, set up your cups. You will want to label each with what they contain, so that you know what it is which produces the response. Roy used little strips of masking tape and a pen to label them, as he did for the last experiment. He then turned the labels so that they were facing away from him.
- When the liquids are all prepared (no grit from the dissolved substances, clear and without any bubbles on the surface) drop a few drops of the red cabbage juice into each cup. If you like, swirl it around to get the colour change throughout.
- Has the juice changed colour? What colour has it turned?
- You can turn the liquids white/clear again by combining an acid with a base, a little at a time. You can tell how strong an acid is by how much of the base it takes to turn it back to a 'clear' liquid, and vice versa.