Potassium Permanganate KMnO_4

Introduction

Johann Rudolf Glauber, a German scientist, made the initial discovery of KMnO₄ synthesis in 1659. This chemical is soluble in water and is dreamed up of potassium and permanganate ions. In its physical condition, it is a dark purple and odourless solid. It is often referred to as Permanganate of Potash or Condy's crystals. As a potent oxidizing agent, dermatitis medicine wound cleaner, and general disinfectant, potassium permanganate is frequently employed in the chemical process industries and laboratories.

What is Potassium Permanganate?

An inorganic substance with the scientific formula KMnO₄ is potassium permanganate. It is a crystalline salt that is purple-black and dissolves in water into a solution of K⁺ and MnO₄^- ion. It is a potent oxidizer that doesn't produce any harmful products. It is listed as one of the critical medicines by the World Health Organization.

KMnO₄ solution

Potassium Permanganate Structure-KMnO₄

• A crystalline solid with a violet hue is what potassium permanganate looks like.

• In the MnO₄^-, i.e., permanganate anion, the manganese atom contains 3 double bonds and 1 solo bond, for a total of four oxygen atoms. This salt has a manganese atom that is in the +7-oxidation number.

• The orthorhombic crystal structure of KMnO_4 has the following lattice constants − a = 910.5 picometers, b = 572.0 picometers, and c = 742.5 picometers.

• The permanganate anion and potassium cation in this molecule has an ionic connection. In a tetrahedral configuration, each MnO₄^- the framework is represented.

Tetrahedral Geometry of KMnO₄

Physical Properties of Potassium Permanganate

Below is a summary of some of the physical attributes of KMnO₄ −

• It is indeed a crystallized solid material with a purple to magenta appearance.

• The most common forms of KMnO₄ are in tablet, powder, or crystalline form.

• It does have a molecular weight of 158.034 gmol^-1 and a density of 2.7gml^-1.

• The melting temperature of KMnO₄ is $\mathrm{2400^\circ C}$,which is high.

• The substance has a savoury flavour but has no scent.

Chemical Properties of Potassium Permanganate

Below is a summary of some of the chemical attributes of KMnO₄.

• Although KMnO₄ is not flammable, it aids in the burning of other materials.

• The solvents acetone, water, pyridine, methanol, and acetic acid are all able to dissolve potassium permanganate. Additionally, inorganic solvents easily break it down.

• It is a very robust combination under normal circumstances, but heating it causes it to break down into MnO₂ and release O₂.

  $$\mathrm{2KMnO_4 → K_2 MnO_4 + MnO_2 + O_2}$$

• It instantly produces fire and smoke when combined with a simple form of alcohol, and glycerol.

• The permanganate postpones ripening, extending the fruit's life span without refrigeration by approximately four weeks.

• It is a potent oxidizing element that produces manganese dioxide, a dark brown substance that dyes anything organically.

• It is employed as a rejuvenation reagent to get rid of iron and hydrogen sulfide, which gives well water a rotten egg odour.

Reactions of Potassium Permanganate (KMnO₄)

Redox reactions make up the majority of reactions involving KMnO₄. One material is oxidized and the other is reduced in a reaction mechanism called a redox reaction. Numerous inorganic substances can be oxidized by potassium permanganate. The solution environment has a significant impact on the reaction's end products. Some of the reactions are listed below −

• The oxidation of aldehydes to generate carboxylic acids is performed by potassium permanganate. For example,

  $$\mathrm{5 C_6 H_{13} CHO+2 KMnO_4+3 H_2 SO_4→ 5 C_6 H_{13} COOH+ 3 H_2 O +K_2 SO_4+2 MnSO_4}$$

• Toluene can be converted to benzoic acid by oxidizing simply an alkyl group on a phenyl ring.

  $$\mathrm{5 C_6 H_5 CH_3+6 KMnO_4+9 H_2 SO_4 → 5 C_6 H_5 COOH+14 H_2 O + 3 K_2 SO_4+6 MnSO_4}$$

• Manganese in KMnO₄ is transformed into Mn⁺² in an acidic environment.

  $$\mathrm{2KMnO_4+5Na_2 SO_3+3H_2 SO_4→ 2MnSO_4+5Na_2 SO_4+K_2 SO_4+ 3H_2 O}$$

• MnO₄^- is reduced in the alkali media to form MnO₄^2-.

  $$\mathrm{2KMnO_4+Na_2 SO_3+2KOH → 2K_2 MnO_4+Na_2 SO_4+H_2 O}$$

• MnO₂ accumulates as a brown deposition in a neutral environment, which MnO₄^- produces.

  $$\mathrm{2KMnO_4+3K_2 SO_3+H_2 O → 3K_2 SO_4+2MnO_2+2KOH}$$

• KMnO₄ is combined with sulfuric acid to generate Mn₂ O₇.

  $$\mathrm{2KMnO_4+H_2 SO_4 → Mn_2 O_7+K_2 SO_4+H_2 O }$$

• KMnO₄ is combined with hydrogen peroxide to generate MnO₂.

  $$\mathrm{2KMnO_4+3H_2 O_2→ 2KOH+2MnO_2+3O_2+2H_2 O }$$

Uses of Potassium Permanganate (KMnO₄)

KMnO₄ has several specialized uses as a potent oxidant that doesn't yield any hazardous consequences. A summary of the uses is listed below −

• In water purification − It is employed in water treatment facilities to eliminate bad odours from water as well as to destroy pollutants. Additionally, it has the potential to purify swimming pool water.

• In the preparation of organic compounds − The use of KMnO₄ as a reactant in the manufacture of organic molecules is one of its main uses. For the manufacture of chloramphenicol, ascorbic acid, saccharin, etc. huge quantities of it are expected.

• In analytical chemistry − Potassium permanganate is used in chemical labs as a chemical to assess what percentage of a compound can be oxidized in a material because of its potent colours and oxidizing properties. The term "permanganate value" is used to describe this value. In the qualitative assessment of organic compounds, KMnO₄ serves to evaluate for unsaturation.

• Uses as a medicine − Several skin disorders can be treated with KMnO₄. This comprises impetigo, tropical ulcers, pemphigus, dermatitis, superficial wounds, and fungal infections of the feet.

Effects on Health

KMnO₄ is a problematic chemical since even a brief interaction can be uncomfortable. The following are a few of its negative health effects −

• It can aggravate the throat and nose whenever swallowed. In particular, the lungs could be impacted, leading to pulmonary oedema, shortness of breath, and coughing.

• Continual exposure could have an impact on fertility.

• The eyes and skin become irritated by concentrated KMnO₄. Extended absorption might irreversibly harm the eyes.

Conclusion

A flexible chemical substance with purple colour is potassium permanganate. It is a manganic acid with potassium salt. Due to its oxidizing qualities, it has a wide range of advantages in the chemical and medical sectors. Ion exchange occurs when aqueous KMnO₄ is treated with an NH₄⁺. Even as a bleaching agent, insecticide, and antiseptic, this substance has many uses.

FAQs

1. Potassium permanganate crystals are safe to touch?

No, on exposure to dried crystalline particles or saturated solutions, potassium permanganate can elicit skin inflammation, redness, and hardening of the skin.

2. How is KMnO₄ disposed of?

Since little volumes of potassium permanganate don't offer a significant threat to the environment or public safety, they are simpler to discard. They can be discarded either at home or at a nearby facility that handles household hazardous garbage.

3. Can potassium permanganate erupt into flames?

When crushed using phosphorus, crystals of KMnO₄ erupt violently.

4. What scientific name does KMnO₄ go by?

The scientific name for KMnO₄ is Potassium manganate (VII)

5. Why does KMnO_4 act as an oxidizer?

The electronegative properties of the elements increase with the oxidation states of the atoms. Hence, permanganate is a good oxidising agent having Mn in a +7 state.