For this application, it turns colourless in acidic solutions and pink in basic solutions.

Phenolphthalein is insoluble in water and usually is dissolved in alcohols for use in experiments. It also serves as a component of universal indicator, together with methyl red, bromothymol blue and thymol blue.

Phenolphthalein is slightly soluble in water and usually is dissolved in alcohols for use in experiments. It is a weak acid, which can lose H+ ions in solution.

The phenolphthalein molecule is colorless, and the phenolphthalein ion is red. When a base is added to the phenolphthalein, the equilibrium shifts, leading to more ionization as H+ ions are removed. This is predicted by Le Chatelier's principle.

Preparation of Phenolphthalein Indicator (Acid/Base Indicator)

1. - Weigh out 1.0 g of phenolphthalein.

2. - Prepare a 50% ethanol (ethyl alcohol) solution consisting of 50ml ethanol and 50 ml water.

3. - Dissolve the phenolphthalein thoroughly in the 50% ethanol solution.