8.26 Describe the preparation of potassium permanganate. How does the acidified permanganate solution react with (i) iron(II) ions (ii) SO2 and (iii) oxalic acid? Write the ionic equations for the reactions.

8.26 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.

Electrolytic oxidation:

(i) 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⁺

(ii) Acidified potassium permanganate oxidiz

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8.26 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.

Electrolytic oxidation:

(i) 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⁺

(ii) Acidified potassium permanganate oxidizes SO₂ to sulphuric acid as follows

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

2H₂O + 2SO₂ + O₂→ 4H⁺ + 2SO₄^2- + 2e^-} x5

Overall: MnO₄ ^- + 4H₂O + 10SO₂ + 5O[₂ → 8H⁺ + 10SO₄ ^2- + 2H⁺

(iii) Acidified potassium permanganate oxidizes oxalic acid to carbon dioxide

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

C₂O₄^2-→ 2CO₂ + 2e^- } x5

Overall: 2MnO₄ ^- + 16H⁺+ 5C₂O₄ ^2- → 2Mn²⁺ + 10CO₂ + 8H₂O

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<p><strong>8.26 </strong>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.</p><p>2MnO₂ + 4KOH + O₂ → 2K₂MnO₄ + 2H₂O</p><p>The Product K₂MnO₄ is extracted with water and then oxidised by passing ozone/chlorine into the solution or electrolytically.</p><p><u>Electrolytic oxidation:</u></p><div><div><picture><source srcset="https://images.shiksha.com/mediadata/images/articles/1687154833phpfziGjj_480x360.jpeg" media="(max-width: 500px)"><img src="https://images.shiksha.com/mediadata/images/articles/1687154833phpfziGjj.jpeg" alt="" width="447" height="179"></picture></div></div><p><strong>(i)</strong> Acidified KMnO₄ solution oxidizes Fe(II) ions to Fe(III) ions and water as product</p><p>MnO₄ ^- + 8H⁺ + 5e^- → Mn²⁺ + 4H₂O</p><p>Fe²⁺→ Fe³⁺+ e^- } x5</p><p><u>Overall:</u> MnO₄ ^- + 8H⁺ + 5Fe²⁺ → Mn²⁺ + 4H₂O + 5Fe³⁺</p><p><strong>(ii)</strong> Acidified potassium permanganate oxidizes SO₂ to sulphuric acid as follows</p><p>MnO₄ ^- + 6H⁺ + 5e^- → Mn²⁺ + 3H₂O } x2</p><p>2H₂O + 2SO₂ + O₂→ 4H⁺ + 2SO₄^2- + 2e^-} x5</p><p><u>Overall:</u> MnO₄ ^- + 4H₂O + 10SO₂ + 5O[₂ → 8H⁺ + 10SO₄ ^2- + 2H⁺</p><p><strong>(iii)</strong> Acidified potassium permanganate oxidizes oxalic acid to carbon dioxide</p><p>MnO₄ ^- + 8H⁺ + 5e^- → Mn²⁺ + 4H₂O} x2</p><p>C₂O₄^2-→ 2CO₂ + 2e^- } x5</p><p><u>Overall:</u> 2MnO₄ ^- + 16H⁺+ 5C₂O₄ ^2- → 2Mn²⁺ + 10CO₂ + 8H₂O</p>

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