11.1 Natural Acid-Base Indicators

Chemical Concept Demonstrated: Acid-base indicators


A number of household products are added to a solution of pureed red cabbage and DI water. The vinegar and baking soda (sodium bicarbonate) are used to determine the colors of the indicator.


Household Product Acid or Base?
Ammonia Base
Bicarbonate soda Base
Drano Base
Tide Base
Muriatic Acid Acid
Vinegar Acid


    Red cabbage contains the anthrocyanin dye, which is a natural acid-base indicator.  Adding household acids and bases to the liquid produced in this experiment changes the color of this dye.

    Generally speaking, acid-base indicators of all kinds work in a similar fashion.  Upon exposure to a certain pH or pH range, the indicator experiences a change in one of its physical properties, most commonly color.