An orange crystalline dye that is the sodium salt of the azo compound of dimethylaniline and sulphanilic acid and is chiefly used as an acid–base indicator, changing from red to yellow-orange over a pH range of 3.1 to 4.4; (CH₃)₂NC₆H₄N=NC₆H₄SO₃Na.
Origin
Late 19th century.
Definition of methyl orange in US English:
methyl orange
noun
Chemistry
An orange crystalline dye that is the sodium salt of the azo compound of dimethylaniline and sulphanilic acid and is chiefly used as an acid–base indicator, changing from red to yellow-orange over a pH range of 3.1 to 4.4; (CH₃)₂NC₆H₄N=NC₆H₄SO₃Na.