What color is phenolphthalein in alkaline solutions?

What color is phenolphthalein in alkaline solutions?

• A. Colorless
• B. Pink
• C. Red
• D. Yellow

Answer: (B)

Phenolphthalein is a common acid-base indicator that changes color depending on the pH of the solution it is in. In alkaline solutions, which are characterized by a higher pH (above 8.2), phenolphthalein exhibits a pink coloration due to the deprotonation of the phenolphthalein molecule, which shifts the equilibrium of its color form. In acidic or neutral solutions, phenolphthalein remains colorless because it exists predominantly in its protonated form. Therefore, the vibrant pink color observed in alkaline conditions is a direct result of the indicator's chemical behavior in response to the pH levels of the solution.

Phenolphthalein is a common acid-base indicator that changes color depending on the pH of the solution it is in. In alkaline solutions, which are characterized by a higher pH (above 8.2), phenolphthalein exhibits a pink coloration due to the deprotonation of the phenolphthalein molecule, which shifts the equilibrium of its color form. In acidic or neutral solutions, phenolphthalein remains colorless because it exists predominantly in its protonated form. Therefore, the vibrant pink color observed in alkaline conditions is a direct result of the indicator's chemical behavior in response to the pH levels of the solution.