The indicator you will use in this reaction is phenolphthalein. Although
phenolphthalein is almost insoluble in water, it is very soluble in alcohol. The odor
from the phenolphthalein solution is from the alcohol. Phenolphthalein is also
commonly used as a cathartic in over-the-counter medication. It is the active
ingredient in commercial laxative Ex-Lax.