Redox indicator
A redox indicator is a reversible (i.e., reversible as often as required) redox system whose reduced and oxidized forms are different in color. A distinction is made between two-color indicators such as ferroin (color change from blue to red) and single-color indicators such as methylene blue (change from blue to colorless) or phenosafranine (change from red to colorless).
A redox indicator is only used for certain redox titrations in order to determine the content of a certain oxidizing or reducing agent. Such an indicator is not required for the redox titration with the strongly violet colored potassium permanganate in manganometry .
Special cases are:
- Diphenylamine (color change colorless - purple), since a step of dye formation, the benzidine rearrangement , irreversibly is
- Resazurin (blue) which when reduced is also irreversibly converted to pink, fluorescent resorufin.
See also
Individual evidence
- ^ Brockhaus ABC Chemie , VEB FA Brockhaus Verlag Leipzig 1965, pp. 574-575.