How do acid base indicators change color?

1 Answer

Acid-base indicators will have protons either added or removed to them depending on the pH level. These changes will cause the indicator to change color.


The video below shows an experiment using an indicator derived from boiling red cabbage. A pigment from the cabbage called anthocyanin is what causes all of the different colors you see.

Other common indicators include:
bromothymol blue
thymol blue
methyl orange
bromocresol green
methyl red
phenol red

Hope this helps!