3 H2S + 2 Kmno4 → 2 Mno2 + 3 S + 2 Koh + 2 H2O = Mno2 + Koh + H2So4

Potassium permanganate (KMn
O4) reacts with hydrogen sulfide (H2S) and give manganese sulfate (Mn
SO4), sulfur, water và potassium sulfate. Manganese atom in KMn
O4 is reduced lớn manganese +2 ion và sulfur atom in H2S is oxidized to lớn sulfur. Purple colour of KMn
O4 is reduced lớn colourless or pale pink colour during the reaction.

Bạn đang xem: 3 h2s + 2 kmno4 → 2 mno2 + 3 s + 2 koh + 2 h2o

Balanced reaction of potassium permanganate and sulfur dioxide reaction is given below.

O4(aq) + 5H2S(g) + 3H2SO4(aq) → 2Mn
SO4(aq) + 5S + 8H2O(l) + K2SO4(aq)


Manganese in potassium permanganate is reduced from +7 oxidation state to +2 oxidation state (Mn2+). As well, sulfur in hydrogen sulfide is oxidized from -2 oxidation state to lớn 0 oxidation state (S).

Because oxidation numbers of several elements in reactants are changed when products are given, this reaction is considered as a redox reaction.

Reaction medium should be slightly acidified by adding few drops of sulfuric acid.

Physical observations during the reaction of potassium permanganate và sulfur dioxide

Dilute aqueous potassium permanganate solution is a purple colour solution. When colourless hydrogen sulfide gas is sent khổng lồ that solution, purple colour of aqueous solution is decreased và become colourless or pale pink colour solution due khổng lồ formation of Mn2+ cations. Also, you can see white - yellow colour precipitate (sulfur) is formed in the solution. Due lớn that sulfur particles, solution becomes unclear.

Safety during the reaction

Hydrogen sulfide is a highly toxic gas and acidic gas. Therefore, be careful khổng lồ prevent any leakages during the treating hydrogen sulfide gas in lớn the potassium permanganate solution.

How lớn balance KMn
O4 and SO2 reaction

Identify oxidation number difference of elements

Because oxidation number of sulfur & manganese atoms are changed, identify what is the difference of oxidation numbers relevant to lớn oxidation và reduction as below.


Exchange difference of oxidation numbers

Oxidation number difference of manganese atom is 5 và sulfur atom is 2. Then, exchange oxidation number difference as bellow.


Balancing number of oxygen atoms

Count the total number of oxygen atoms in the left side & right side separately. To lớn balance the number oxygen atoms, địa chỉ cửa hàng 8 H2O molecules khổng lồ the right side od the reaction.

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Balancing number of hydrogen atoms

Count the total number of hydrogen atoms in the left side & right side separately. To lớn balance number hydrogen atoms, showroom 4 H+ ions khổng lồ the right side.


Now, we have obtained the balanced ionic equation of KMn
O4 và H2S reaction.

Balancing chemical equation

Now, we can balance the ionic equation & find chemically balanced equation.


Ask Your Chemistry Questions
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Advanced Level

Hydrogen sulphide, potassium permanganate, & sulfuric acid (H2S KMn
O4 H2SO4) are available in almost all chemical labs across the World. In the H2SO4 medium, KMn
O4 and H2S react mainly. The reaction is a Redox reaction.

O4 H2SO4

The chemical compound with the chemical formula H2S is Hydrogen sulfide. It is a colorless gas with rotten eggs ‘ distinctive foul smell. Besides it is very poisonous as well as corrosive và flammable also.

Potassium permanganate is a compound and medication of inorganic chemical substances. It is a strong oxidizing agent. KMn
O4 is a salt consisting of K+ and Mn
O4 -1 ion and has the chemical formula KMn
O4. Khổng lồ offer intensely pink or purple alternatives, it dissolves in water. In Solid-state it forms prismatic purplish-black glistening crystals.

Sulphuric acid is indeed a mineral acid having a molecular formula H2SO4 It is a colorless, odorless, và syrupy liquid that is soluble in water. In this reaction, it acts as an acidic medium only.

Hydrogen sulphide reacts with potassium permanganate & sulfuric acid

Hydrogen sulphide reacts with potassium permanganate & sulfuric acid khổng lồ produce Sulfer, Manganese Sulfate, potassium sulfate as well as water.

O4 + H2S + H2SO4 = S + + K2SO4 + Mn
SO4 + H2O

Now by using the ion-electron method we can balance the Oxidation-Reduction reaction.


Ion-Electron method

Ion-electron method is a very effective method to lớn balance equations of the Redox reactions. As the above reaction is a redox reaction, we can use the ion-electron method to balance the reaction equation. Let’s try-

The skeleton reaction for the redox reaction is-

O4 + H2S + H2SO4 = S + + K2SO4 + Mn
SO4 + H2O

Here,The Oxidizing agent: KMn
O4 or Mn
The Reducing agent: H2S or, S-2

Reduction Half Reaction:

⇒ Mn
O4 -1 +5e + 8H+  = Mn2- + 4H2O … …. …. …. (1)

Oxidation Half Reaction:

⇒ S-2 – 2e– = S … … … … (2)


equation (1)x2 + (2)x5,

O4-1 +10e– + 16H+  = 2Mn2- + 8H2O

5S-2 – 10e– = 5S

⇒ 2Mn
O4 -1 + 5 S-2 + 16H+ = 2Mn2- + 8H2O +5S

⇒ adding necessary ions and radicals we get,

⇒ 2KMn
O4 + 5H2S + 3H2SO4 = 5S + K2SO4 + 2Mn
SO4 + 8H2O


O4 + 5H2S + 3H2SO4 = 5S +K2SO4 + 2Mn
SO4 + 8H2O

Click to readily understand ion-electron balancing redox reaction

O4 + H2O2 + H2SO4 = O2 + Mn
SO4 + K2SO4 + H2O

SO4 + KMn
O4 + H2SO4 = Fe2(SO4)3 + Mn
SO4 + H2O + K2SO4

Cl + KMn
O4 + H2SO4 = Cl2 + Mn
SO4 + Na2SO4 + K2SO4 + H2O

K2Cr2O7 + Fe
SO4 + H2SO4 = Cr2(SO4)3 + Fe2(SO4)3 + K2SO4 + H2O

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2 Comments Posted
October 27, 2020 at 11:58

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