The decolourization of purple colour of tetraoxomanganate (VII) ion is a test for

The decolourization of the purple colour of tetraoxomanganate (VII) ion is a test for alkenes. Alkenes are unsaturated hydrocarbons that contain at least one carbon-carbon double bond. In this test, the purple colour of tetraoxomanganate (VII) ion is due to the presence of this ion in a solution, which is added to the unknown compound. If the unknown compound is an alkene, it will react with the tetraoxomanganate (VII) ion and the purple colour will disappear. This is because alkenes can reduce tetraoxomanganate (VII) ion to manganese(II) ions, which are responsible for the colourless solution. Therefore, the decolourization of purple colour of tetraoxomanganate (VII) ion is a test for the presence of alkenes in a compound.