What color does phenolphthalein turn in a basic solution?

Phenolphthalein acts as a pH indicator and undergoes a distinct color change in response to the acidity or basicity of a solution. In acidic solutions (pH below 7), phenolphthalein remains colorless. However, as the pH increases and the solution becomes basic (above pH 8.2), phenolphthalein transitions to a pink color, which indicates the presence of hydroxide ions.

This color change is due to the structural transformations of the phenolphthalein molecule, which result in different light absorption properties. In a basic solution, the conjugate base form of phenolphthalein is more prevalent, which absorbs light differently than its acidic form, leading to the visible pink color.

Understanding the behavior of phenolphthalein as a pH indicator is essential for various applications in titration and chemical analysis, as its color change provides a clear visual signal of the solution's pH level.