Students will be introduced to acidic and basic liquids through this simple test.
- clear plastic cups
- a head of purple cabbage coarsely shred.
- paper towels
- *safety glasses
- white vinegar
Can do this activity as a demonstration or in class groups. Take extra care with the ammonia, though.
- Boil the shredded cabbage in a 1/2 a pot of water for about ten minutes. Strain and refrigerate until ready to use.
- Fill cups about half way with each liquid.
- Add one teaspoon of the boiled cabbage to each glass. What happened? Cabbage should change colour:
- vinegar – red – acid
- ammonia – green – base
- water – purple – neutral
- Based on these colour changes, try to predict whether other liquids are acidic or basic, then add the boiled cabbage to find out. Extension: Make your own indicator paper.
- Soak paper towels or white coffee filters in purple cabbage juice.
- Let dry and cut into strips. The strip should change colour according to the type of liquid it’s dipped into.