Forget the Indicator Poem

Mural reads: Phenopthalein is pink, bromocresol is green, if you forget the indicator, the reaction will go unseen.

A titration experiment allows an experimenter to determine the equivalence point of an acid base reaction: when the OH- (or H+) added is equal to the H+ (or OH-) already in solution. It is possible to see when this point has occurred because an indicator is added that is a different color in acidic or basic solution. (For example, In- is blue and HIn is yellow, where In stands for indicator). If the indicator is forgotten, it is not possible to see when the equilibrium point is reached and the titration is complete, defeating the entire purpose of the experiment.

The colors in the poem are the colors of the indicators at equilibrium.