Methyl red is one of the commonly used acid-base indicators. The usual concentration is 0.1% ethanol solution, pH 4.4 (red)-6.2 (yellow).

Function:
Acid-base indicator, pH discoloration range 4.4 (red) ~ 6.2 (yellow); titration of ammonia, weak organic bases and alkaloids, but not applicable to organic acids other than oxalic acid and picric acid; can be used with bromocresol green and methylene blue Composed of mixed indicators to shorten the color change domain and improve the sensitivity of color change; adsorption indicator for precipitation titration, such as titration of fluoride ion with thorium nitrate; verification of free chlorine, chlorite and other oxidants.