Question

What is the colour of the permanganate ion?

Answer 1

1. Permanganate ion (${\mathrm{MnO}}_4^{2-}$) is a chemical compound with a molar mass of $118.934{\mathrm{gmol}}^{-1}$.
2. It is a strong oxidizing agent which has tetrahedral geometry.
3. It is synthesized by the oxidation of Magnesium based compound by using a strong oxidizing agent: $$\begin{gathered} 2{\mathrm{MnCl}}_2\left(\mathrm{s}\right)+5\mathrm{NaClO}\left(\mathrm{aq}\right)+6\mathrm{NaOH}\left(\mathrm{aq}\right)\to 2{\mathrm{NaMnO}}_4\left(\mathrm{s}\right)+9\mathrm{NaCl}\left(\mathrm{s}\right)+3{\mathrm{H}}_2\mathrm{O}\left(\mathrm{aq}\right) \\ \mathrm{Manganese}\mathrm{Sodium}\mathrm{Sodium}\mathrm{Sodium}\mathrm{Sodium}\mathrm{Water} \\ \mathrm{chloride}\mathrm{hypochlorite}\mathrm{hydroxide}\mathrm{permanganate}\mathrm{Chloride} \end{gathered}$$

The importance of the permanganate ion is described below:

1. It has a deep purple colour.
2. Colour is not due to the d-d transition orbital.
3. Colour is due to Ligand-to-Metal Charge-Transfer (LMCT).