Chemical Concept Demonstrated: Acid-base indicators
Demonstration:
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.
Observations:
| Household Product | Acid or Base? |
| Ammonia | Base |
| Bicarbonate soda | Base |
| Drano | Base |
| Tide | Base |
| Muriatic Acid | Acid |
| Vinegar | Acid |
Explanation:
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.