Phenol red

Phenol red is a pH indicator dye used in laboratories to measure the acidity or alkalinity of solutions. When added to a liquid, it changes color depending on the pH level: it appears yellow in acidic conditions (pH below 6.8), red in neutral environments (around pH 7.4), and pink or magenta in alkaline solutions (pH above 8.2). This color change helps scientists and healthcare professionals quickly assess the acidity of biological fluids, such as urine, or reactions in chemical experiments, providing valuable information about the sample's chemical nature.