- Unit of Measure :
Di Methyl Yellow
Methyl yellow, or C.I. 11020, is a chemical compound which may be used as a pH indicator. Methyl yellow (pH indicator) below pH 2.9 above pH 4.0 2.9 â 4.0 In aqueous solution at low pH, methyl yellow appears red. Between pH 2.9 and 4.0, methyl yellow undergoes a transition, to become yellow above pH 4.0. Additional indicators are listed in the article on pH indicators.