Suggested Grades

3+

Objective

Students will be introduced to acidic and basic liquids through this simple test.

Materials

• clear plastic cups
• a head of purple cabbage coarsely shred.
• spoons
• paper towels
• *safety glasses
• white vinegar
• ammonia
• water

Method

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.