Make your own pH paper strips

Overview

Anthocyanin is a chemical found in plants such as cabbage, roses, and berries. It will change color based on the presence of an acid or a base.

Chemicals

  • 100 mL water

  • 50 mL Rubbing alcohol

  • 3 leaves of cabbage or 1 rose 
    or 1/2 cup of berries

Affiliate links to chemicals.

*Note: These chemicals can be purchased locally at stores such as Walmart/Target.

Materials

  • Glass beaker

  • Small beaker

  • Blender

  • Erlenmeyer flask

  • Piece of paper

  • Strainer

  • Alcohol burner + stand + lighter

Procedure

1. In Erlenmeyer flask, pour in water and boil on alcohol stand.

2. In blender, blend boiling water and cabbage/rose/berries for 2 minutes.

3. In plastic beaker, measure isopropanol and pour into glass beaker.

4. In glass beaker, strain in blended liquid and isopropanol.

5. Submerge a paper in the glass beaker.

6. Let dry and cut into strips.

The Science Behind the Reaction

Anthocyanins are chemicals that change color when introduced to certain conditions: purple for neutral conditions (pH 7.0), red for acidic conditions (pH < 7.0), and blue for basic conditions (pH>7.0).

Keep Experimenting!

1. Compare the acidity of the different drinks in your fridge.

2. Paint a whole sheet with the liquid and then sprinkle on baking soda and lemon juice for a creative work of art!