Azo violet

Azo violet
Identifiers
Jmol-3D images Image 1
Properties
Molecular formula C12H9N3O4
Appearance dark red to brown crystalline powder
Density 1.45 g/cm3
Solubility in water 1 g/L H2O; 4 g/L Ethanol
Hazards
Flash point 261.7 °C
 YesY violet (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Azo violet is an organic compound with the chemical formula C12H9N3O4. It is used as a dye and a pH indicator. It forms blue colour with magnesium in slightly alkaline medium. This reaction depends on adsorption of the dye on magnesium hydroxide. Ammonium ions reduce sensitivity of reaction.

Any salt or salt solution containing magnesium will give this Violet colouring of solution. However, ammonium compounds such as ammonium chloride or ammonium hydroxide will give a different colour based on amount used. Still, it is used as identification test for magnesium.