red cabbage test

• what do you need?

  • a red cabbage
  • boiling water
  • a bowl
  • a selection of acid/alkaline substances
• what is step 1?

  cut cabbage into small slices
• what is step 2?

  put cabbage slices in a pot and pour enough water to cover them
• what is step 3?

  boil for half an hour then turn off the heat and let the temperature cool down
• what is step 4?

  pour the blue-violet liquid you have made into a large, low container
• what is step 5?

  pour some drops of the liquid on a white surface and observe its changes of colour when its mixed with different substances.
• what happened?


  the cabbage juice turns red when it mixes with something acidic and turns green when it mixes with something basic. Red cabbage juice is an indicator as it shows is something about the chemical composition of other substances.
• what about the cabbage makes it an indicator?

  red cabbage contains a water-soluble pigment called anthocyanin that changes colour when it’s mixed with an acid or a base. It turns red in acidic environments with a pH less than 7 and turns blueish-green in alkaline (basic) environments with a pH greater than 7.
• what is step 1 of making your own litmus paper?

  cut some porous white paper into rectangles and soak in juice so they absorb it.
• what is step 2 of making your own litmus paper?

  after half an hour, remove the cards and put them away to dry.
• what is step 3 of making your own litmus paper?


  cut the cards into strips.