Answer:
to identify the pH of a solution
Step-by-step explanation:
Indicators are substances whose colour solutions change due to changes in the pH. They are usually weak acids or bases, but their conjugate base or acid forms have different colors due to differences in their absorption spectra. they are usually used during titration to indicate end points of an experiment. The colour of an indicator alters when the concentration of a certain chemical species, reaches a critical range of values.