Phenolphthalein Disodium Salt is widely used as a pH indicator in various analytical applications. It is particularly effective in titrations to determine the endpoint in acid-base reactions, where it changes color from colorless to pink in the pH range of 8.2 to 10.0. This property makes it a valuable tool in laboratories for measuring the acidity or alkalinity of solutions. Additionally, it is employed in educational settings to demonstrate pH changes in chemistry experiments. In some cases, it is also used in medical diagnostics for specific tests, though its use in this field has declined due to safety concerns. Its clear and distinct color transition ensures reliable and accurate results in quantitative analysis.