KMnO4 is a strong oxidizing agent and can react with molecules having higher reduction potential. Let us see in detail the mechanism of its reaction with H2SO4.
Potassium permanganate is a purple violate solid molecule and it is a powerful reagent as the central metal Mn presents a +7 oxidation state. It can react with a cold and concentrated form of sulfuric acid and form different oxidized products. In this reaction, KMnO4 acts as a self catalyst.
Let us discuss the mechanism of the reaction between sulfuric acid and iron, the reaction enthalpy, the type of reaction, product formation, etc in the following part of the article.
1. What is the product of H2SO4 and KMnO4?
Manganese sulfate and Potassium sulfate are formed as major products when H2SO4 and KMnO4 are reacted together. Water molecules and oxygen gas are also evolved due to their reaction.
between H2SO4 and KMnO4
2. What type of reaction is H2SO4 + KMnO4?
H2SO4 + KMnO4 reaction is an example of a double displacement reaction along with redox and precipitation reactions. It is also oxygen evolved reaction along with a hydrolysis reaction.
3. How to balance H2SO4 + KMnO4?
H2SO4 + KMnO4 = MnSO4 + K2SO4 + H2O + O2 We have to balance the equation in the following way:
- Step 1 – Labelling all the reactants and products by the required number of alphabets
- First, we labeled all the reactants and products by A, B, C, D, and E as there are only five different atoms obtained for this reaction and the reaction looks like: A H2SO4 + B KMnO4 = C MnSO4 + D K2SO4 + E H2O + F O2
- Step 2 – Equating all the Coefficients for all the same type of elements by rearranging them
- After the rearrangement of all the coefficients of the same elements by their stoichiometric proportion we get, H = 2A = 2E, S = A = C = D, O = 4A = 4B = 4C = 4D = E =2F, Mn = B = C, K = B = 2d
- Step 3 – Using Gaussian elimination to determine the coefficient values
- Using the Gaussian elimination and equating all the equations we get, A = 6, B = 4, C = 4, D = 2, E = 6, and F= 5,
- Step 4- now write the whole equation in the balanced form
- The overall balanced equation will be,
- 6 H2SO4 + 4 KMnO4 = 4 MnSO4 + 2 K2SO4 + 6 H2O + 5 O2
4. H2SO4 + KMnO4 titration
To estimate the quantity of potassium or manganese we can perform a titration between KMnO4 and H2SO4
Apparatus used
We need a burette, conical flask, burette holder, volumetric flask, and beakers for this titration.
Titre and titrant
H2SO4 versus KMnO4, H2SO4 acts as a titrant which is taken in the burette and the molecule to be analyzed is KMnO4 which is taken in a conical flask.
Indicator
The whole titration is done in acidic pH as the concentration of H2SO4 is high and for this reaction, KMnO4 acts as a self-indicator because it is a colored solution and in different pH, it changes color.
Procedure
The burette was filled with standardized H2SO4 and KMnO4 was taken in a conical flask along with the respective indicator. H2SO4 is added dropwise to the conical flask and the flask was shaking constantly. After a certain time when the endpoint arrived KMnO4 changes its color.
We repeat the titration several times for better results and then we estimate the potassium as well as manganese quantity by the formula V1S1 = V2S2.
5. H2SO4+ KMnO4 net ionic equation
The net ionic equation between H2SO4 + KMnO4 is as follows,
2H+ + SO42- + K+ + MnO4– = Mn2+ + K+ + SO42- + H+ + OH– + O2
- To derive the net ionic equation the following steps are required,
- First H2SO4 will be ionized in proton and sulfate ions as it is a strong electrolyte
- After that KMnO4 also dissociated to K+ ion and SO42-.
- After that, the product MnSO4 also dissociated to Mn2+ which is d5 stable configuration and corresponding SO42-.
- Water is also ionized to H+ and OH-.
- O2 remains undissociated.
6. H2SO4+ KMnO4 conjugate pairs
In the reaction, H2SO4 + KMnO4 conjugate pairs will be the corresponding de-protonated and protonated form of that particular species which are listed below-
- Conjugate pair of H2SO4 = SO42-
- Conjugate pair of OH– = H2O
7. H2SO4 and KMnO4 intermolecular forces
The intermolecular force between H2SO4 is an electrostatic, covalent force. For the KMnO4 it is ionic interaction and for MnSO4 and K2SO4 the ionic interaction is along with the coulombic force. H-bonding is present in water and van der waal’s force acts in O2 molecules.
| Molecule | Acting force |
| H2SO4 | Electrostatic, van der waal’s Dipole interaction |
| KMnO4 | Ionic, metallic, and electrostatic |
| K2SO4 / MnSO4 | Coulombic force, strong ionic interaction |
| H2O | Covalent, H-bonding |
| O2 | Van der Waal’s force, London force |
8. H2SO4 + KMnO4 reaction enthalpy
In the reaction, H2SO4 + KMnO4 reaction enthalpy is,-4400.4 KJ/mol which can be obtained by the formula enthalpy of products – enthalpy of reactants, and here the change in enthalpy is positive.
| Molecule | Enthalpy (KJ/mol) |
| KMnO4 | -813 |
| H2SO4 | -814 |
| MnSO4 | -1130 |
| K2SO4 | -1437.8 |
| H2O | -68 |
| O2 | 0 |
and Products
9. Is H2SO4 + KMnO4 a buffer solution?
The reaction between H2SO4 + KMnO4 gives a buffer solution and they can control the pH of the solution.
10. Is H2SO4 + KMnO4 a complete reaction?
The reaction between H2SO4 + KMnO4 is the complete reaction because it gives two complete products MnSO4 and K2SO4 along with O2 gas.
11. Is H2SO4 + KMnO4 an exothermic or endothermic reaction?
The reaction H2SO4 + KMnO4 is exothermic in terms of thermodynamics first law. So, the reaction releases more energy and temperature to the surrounding so we have to be more cautious, Where δH is always negative.
12. Is H2SO4 + KMnO4 a redox reaction?
The reaction between H2SO4 + KMnO4 is a redox reaction because in this reaction many elements get reduced and oxidized.
H2SO4 and KMnO4 Reaction
13. Is H2SO4 + KMnO4 a precipitation reaction
The reaction H2SO4 + KMnO4 is a precipitation reaction because it gets precipitated in the solution and is not soluble in the reaction mixture.
14. Is H2SO4 + KMnO4 reversible or irreversible reaction?
The reaction between H2SO4+ KMnO4 is irreversible because we get O2 gas as a product. When gas is formed during the reaction, the entropy of the reaction increases and the equilibrium of the reaction shifts towards the right-hand side only.
15. Is H2SO4 + KMnO4 displacement reaction?
The reaction between H2SO4+ KMnO4 is an example of single displacement reaction because in the above reaction Mn and K are displaced by H+ in H2SO4 and O2 gas becomes free from the reaction.
Conclusion
H2SO4 and KMnO4 reaction mainly gives us K2SO4 and MnSO4 along with oxygen gas so it is a commercially important reaction for the production of oxygen gas. Also, the quantitative analysis of the H2SO4 and KMnO4 give the amount of Mn and K in the respective sample.
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Hi……I am Biswarup Chandra Dey, I have completed my Master’s in Chemistry from the Central University of Punjab. My area of specialization is Inorganic Chemistry. Chemistry is not all about reading line by line and memorizing, it is a concept to understand in an easy way and here I am sharing with you the concept about chemistry which I learn because knowledge is worth to share it.