Potassium Permanganate

Potassium permanganate (KMnO4) is an inorganic compound. It is a dark brown-black salt, soluble in water such as  K + and MnO-4, a very pink to purple solution. It is a strong oxidizer, has medicinal properties and is widely used to clean wounds and dermatitis.

Preparation of potassium permanganate

1. Potassium permanganate is industrially produced from manganese dioxide, which also occurs as a mineral pyrolusite. MnO2 is mixed with potassium hydroxide and heated to air or another source of oxygen, such as potassium nitrate or potassium chlorate. This process provides potassium manganate:

2 MnO2 + 4 KOH + O2 → 2KMnO4 + 2 H2O

1.     The Potassium manganate changed to permanganate by electrolytic oxidation in basic medium:

2 K2MnO4 + 2 H2O → 2 KMnO4 + 2 KOH + H2

1. Although it has no commercial value, potassium manganate can be oxidised with chlorine or vice versa under acid conditions. The reaction of chlorine oxidation is

2 K2MnO4 + Cl2 → 2 KMnO4 + 2 KCl

1. By disproportionation reaction:

3 K2MnO4 + 4 HCl → 2 KMnO4 + MnO2 + 2 H2O + 4 KCl

1. By carbonic acid reaction:

3 K2MnO4 + 2 CO2 → 2 KMnO4 + 2 K2CO3 + MnO2

Permanganate salt may be produced by treating a solution of Mn2+ ions with strong compounds such as sodium bismuthate (NaBiO3), lead dioxide (PbO2) or peroxydisulfate. The presence of manganese tests using the clear violet colour of permanganate produced by these reagents.

Chemical properties of potassium permanganate

1. It is a combination of crystalline purple.
2. It dissolves in water. When burned alone or with alkali, it decomposes with evaporative oxygen.
3. In treatment with concentrated H2SO4, makes manganese heptoxide with permanganate sulphate which decomposes on burning.
4. Potassium permanganate is a powerful oxidising agent. The mixture of sulphur, coal and KMnO4 makes an explosive powder.
5. A mixture of oxalic acid and KMnO4 catches fire automatically after a few seconds. The same thing happens when glycerine is poured over KMnO4 powder.

Physical properties of potassium permanganate

KMnO4 is available as a glossy purple solid. It is odourless and has a concentration of 2.70 g / mL and melting point of 240 ° C. It is available for sale as a powder, crystals or tablets.

Uses of potassium permanganate

Due to the oxidising properties of potassium permanganate, it has several applications. These are:

1. Medicinal uses:

Potassium permanganate is used for many skin conditions. These include fungal infections of the feet, impetigo, pemphigus, external wounds, dermatitis and topical sores.

2. Treatment of water:

Potassium permanganate is widely used in the water treatment industry. It is used as a rejuvenating chemical to remove iron and hydrogen sulphide (rotten egg odour) from spring water through the “Manganese Greensand” Filter. “Pot-Perm” is also available in water stores and is used to treat wastewater. It has historically been used to disinfect drinking water and can turn water into pink. It is currently used to control endangered species such as zebra mussels in freshwater collection and treatment programs.

3. Organic compound synthesis:

KMnO4 finds extensive use as a reagent for biological synthesis. Essential amounts are required to combine ascorbic acid, chloramphenicol, saccharin, isonicotinic acid and pyrazinoic acid.

KMnO4 is used in organic quality analysis to assess non-compliance. It is sometimes called the Baeyer reagent after German biochemist Adolf von Baeyer. The reagent is an alkaline solution of potassium permanganate. Reactions with double or triple bonds (-C = C- or -C≡C-) cause the colour to fade from purple-pink to brown. Aldehydes and formic acids (and formats) also provide a good test.

4. Preservation of fruits:

Ethylene ingredients increase the banana storage time even at high temperatures. This effect can be applied by packing bananas in polyethylene and potassium permanganate. By removing ethylene by oxidation, permanganate slows down ripening, prolonging the shelf life of the fruit up to 4 weeks without the need for freezing.

Other reactions of potassium permanganate

1. Thermal decomposition:

When heated, solid potassium permanganate decomposes to potassium manganate

2 KMnO4 → K2MnO4 + MnO2(s) + O2

2. Acidic reactions:

The permanganate reaction with concentrated hydrochloric acid gives chlorine. Products containing Mn from redox reactions depend on pH. Acidic permanganate solutions are reduced to pink manganese II ion (II) (Mn2 +) and water. In a neutral solution, permanganate is reduced only by three electrons to provide manganese dioxide (MnO2), where manganese is in the +4-oxidation state. This substance contaminates a person’s skin when in contact with KMnO4. KMnO4 automatically degrades the alkaline solution into green K2MnO4, where manganese is in the +6-oxidation state.

Conclusion

Potassium permanganate is also called Condy’s crystals or hypermanganate. It is a very useful inorganic chemical that has antibacterial properties. It reacts with acids and bases to form various compounds with different applications. Though potassium permanganate has numerous uses, it also causes many hazards to human life.