Alizarin red is commonly used as a pH indicator in analytical chemistry, particularly in titrations and pH testing where a visible color change is required. It exhibits a distinct color transition in the pH range of approximately 4.0 to 6.0, shifting from yellow to red or violet, making it useful for detecting weakly acidic to near-neutral conditions. It is also employed in biological staining to identify calcium deposits in tissues, especially in bone and cartilage studies. In environmental testing, alizarin red solution helps in the detection of metal ions in water samples due to its ability to form colored complexes with certain cations. Additionally, it finds application in educational labs for demonstrating acid-base reactions due to its clear and sharp color change.