Describe the preparation of potassium permanganate. How does the acidified permanganate solution react with (i) iron(II) ions (ii) SO2 and (iii) oxali

Potassium permanganate can be prepared from MnO2. It can be done by fusing the ore with KOH in presence of an oxidizing agent like atmospheric oxygen/KNO3 etc to give green coloured K2MnO4 as the product.

2MnO2 + 4KOH + O2 ¬--> 2K2MnO4 + 2H2O

The Product K2MnO4 is extracted with water and then oxidised by passing ozone/chlorine into the solution or electrolytically.

At Anode, manganite ions are oxidized to permanganate ons.

1)Acidified KMnO4 solution oxidizes Fe(II) ions to Fe(III) ions and water as product

MnO4- + 8H+ + 5e- --> Mn2+ + 4H2O

Fe2+--> Fe3++ e- } x5

Overall: MnO4- + 8H+ + 5Fe2+ --> Mn2+ + 4H2O + 5Fe3+

2)Acidified potassium permanganate oxidizes SO2 to sulphuric acid as follows:

MnO4- + 6H+ + 5e- --> Mn2+ + 3H2O } x2

2H2O + 2SO¬2 + O2 --> 4H+ + 2SO42- + 2e-} x5

Overall:MnO4- + 4H2O + 10SO¬2 + 5O2-->8H+ + 10SO42- + 2H+

3)Acidified potassium permanganate oxidizes oxalic acid to carbon dioxide 

MnO4- + 8H+ + 5e- --> Mn2+ + 4H2O} x2

C2O42- --> 2CO2 + 2e- } x5

Overall:  2MnO4- + 16H++ 5C2O42- --> 2Mn2+ + 10CO2 + 8H2O