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Describe the preparation of potassium permanganate from pyrolusite ore. Write balanced chemical equation for one reaction to show oxidizing nature of potassium permanganate. |
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Answer» Solution :Formation of `KMnO_4`: It is prepared by fusing pyrolusite ore `(MnO_2)` with caustic potash (KOH) or POTASSIUM CARBONATE in the presence of air to give a green mass due to the formation of potassium manganate. `2MnO_2 = 4KOH + O_(2) overset("heat")(rarr) underset("(green mass)")underset("Magnanate")underset("Potassium")(2K_2MnO_4)+2H_2O` `2MnO_2 + 2K_2CO_3 + O_3 rarr underset("Maganate")underset("Potassium")(2K_2MnO_4) + 2CO_2` The solution is then TREATED with a CURRENT of chlorine or ozone to oxidise potassium manganate to potassium permanganate. The solution is concentrated and the dark purple crystals of potassium permanganate separate out. `2K_2MnO_4 + Cl_2 to 2KCI + 2KMnO_4` `2K_2MnO_4 + O_3 +H_2O rarr 2KMnO_4 + 2KOH +O_2` Oxidizing action of acidified `KMnO_4` on iron (II) ions . `2KMnO_4 + 3H_2SO_4 to K_2SO_4 + 2MnO_4 + 3H_2O + 5[O]` `([2FeSO_4 + H_2SO_4 + [O] to Fe_(2)(SO_4)_(3) + H_2O] xx 5)/(2KMnO_4 + 8H__2SO_4 + 10FeSO_4 rarr K_2SO_4 + 2MnO_4 + 5Fe_2(SO_4)_(3) + 8H_2O)` |
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