Explain the colour of MnO4- ion.

1.	Explain the colour of MnO4- ion.
Answer» i. MnO^-₄ ion is intense purple coloured in solution. ii. The colour is due to charge transfer. An electron is temporarily transferred from O^-2to Mn⁷⁺ in MnO^-₄. iii. Due to this, there is a temporary change in the oxidation state of oxygen from -2 to -1 and manganese from +7 to +6. iv. Charge transfer is possible when the energy levels on the two different atoms involved are appreciably close. Note: Cr₂O₇^2- , Cr₂O₄^- , MnO₄^- , Cu₂O and Ni-DMG complex are coloured due to charge transfer transitions.

Answer»

i. MnO^-₄ ion is intense purple coloured in solution.

ii. The colour is due to charge transfer. An electron is temporarily transferred from O^-2to Mn⁷⁺ in MnO^-₄.

iii. Due to this, there is a temporary change in the oxidation state of oxygen from -2 to -1 and manganese from +7 to +6.

iv. Charge transfer is possible when the energy levels on the two different atoms involved are appreciably close.

Note: Cr₂O₇^2- , Cr₂O₄^- , MnO₄^- , Cu₂O and Ni-DMG complex are coloured due to charge transfer transitions.

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