Methyl red is an organic compound that functions as a pH indicator, changing color from red in acidic solutions to yellow in basic ones. Its chemical formula isC15H15N3O, and it is also used in microbiology for tests like the mixed acid fermentation test to identify bacteria.
Properties and uses
- pH indicator: It is red in solutions with a pH below 4.4 and yellow in solutions with a pH above 6.2. In the intermediate range (pH 4.4 to 6.2), it appears orange.
- Chemical classification: It is an azo dye and a monocarboxylic acid.
- Appearance: It is a dark red crystalline powder.
- Solubility: It is insoluble in water but soluble in alcohol and acetic acid.
- Applications:
- Used in acid-base titrations to determine the endpoint of a reaction.
- Employed in microbiology to identify enteric bacteria like E. coli through the mixed acid fermentation test.
