Red Cabbage Does Stuff
What you will need for this experiment:
- Grate 1/2 the cabbage into a bowl. Fill the bowl with water
and let it sit for a couple of hours. Drain the cabbage water into the other
bowl. OR. Put the grated cabbage into the saucepan with enough water to just
cover it. Boil for 20-30 minutes until the liquid turns a dark purple
- Let the cabbage juice cool and then strain into the
- Cut 2 inch (5 cm) strips out of the paper towels/coffee
- Soak the strips of paper in the cabbage juice until they
- Lay the strips flat on the bench/table and leave
them to dry. These are your indicator strips.
- Put the other
liquids (lemon juice etc.) into separate cups.
- Dip the indicator
strips into one liquid each.
- Using pencils and your plain paper,
copy the colour that each strip turns.
- Draw a picture, or write the
name of the liquid that made the paper turn that colour.
- Use your
notes to make a chart showing the different colours that the liquids
Your red cabbage juice is a simple
pH tester. It reacts differently to different substances. Once you know
what colour the juice turns in acids and alkalis, you can use it to test
Why It Happens:
Red cabbage has pigments which
react differently to acids and alkalis. When you dip the strips into a
substance and wait for a few minutes, the colour will fully develop. The
indicator strips turn red-yellow in acid, green in neutral and purple-blue