Chemistry - Chemical Equilibrium Question with Solution | TestHub

A dye molecule is made up of two different part (i) Chromophore (ii) Auxochrome. The groups which produce colour in a compound i.e., chromophores are usual unsaturated groups like nitro, nitroso, azo, azoxy, carbonyl and olefinic bonds Auxochrome are usually acidic / basic functional group like$-\mathrm{OH},-\mathrm{COOH},-{\mathrm{SO}}_3\mathrm{H},-{\mathrm{NH}}_2,-\mathrm{NHR},-{\mathrm{NR}}_2$.

A compound containing only a chromophore may be coloured material but not a dye. For example azo benzene is red coloured but not a dye. Where as para amino azobenzene (anilineyellow) is a dye.