15 Facts on H2SO4 + Mn2O7: What, How To Balance & FAQs

Mn2O7 is an acidic molecule so it can react with acid molecules stronger. Let us see what happens when H2SO4 reacts with Mn2O7.

In Mn2O7, the oxidation state of Mn is +7, so it is the most oxidizing agent and can undergo reduction and can oxidize other elements or molecules. The molecule is also known as manganese heptaoxide where the Mn-O-Mn bond is observed along with double-bonded oxygen.

The reaction between Mn2O7 and H2SO4 does not require any kind of catalyst or temperature. Let us discuss the mechanism of the reaction between sulfuric acid and manganese, 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 Mn2O7?

Manganese sulfate is formed as the major product when H2SO4 and Mn2O7 are reacted together along with water molecules.

H2SO4 + Mn2O7 = Mn2(SO4)7 + H2O

2. What type of reaction is H2SO4 + Mn2O7?

The reaction between H2SO4 + Mn2O7 is an example of a double displacement reaction along with redox and precipitation reactions. It is also a hydrolysis reaction.

3. How to balance H2SO4 + Mn2O7?

We have to balance the equation, H2SO4 + Mn2O7 = Mn2(SO4)7 + H2O in the following way:

  • First, we label 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 thisA H2SO4 + B Mn2O7 = C Mn2(SO4)7 + D H2O
  • 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 = 2D, S = A = 7C, O = 4A = 7B = 28C = D, Mn = 2B = 2C
  • Using the Gaussian elimination and equating all the equations we get, A = 7, B = 1, C = 1, and D = 7
  • Now write the whole equation in the balanced form
  •  The overall balanced equation will be,
    7H2SO4 + Mn2O7 = Mn2(SO4)7 + 7H2O

4. H2SO4 + Mn2O7 titration

To estimate the quantity of manganese we can perform a titration between Mn2O7 and H2SO4

Apparatus used

We need a burette, conical flask, burette holder, volumetric flask, and beakers for this titration.

Titre and titrant

H2SO4 acts as a titrant which is taken in the burette and the molecule to be analyzed is Mn2O7 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, Mn2O7 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 Mn2O7 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, Mn2O7 changes its color.

We repeat the titration several times for better results and then we estimate manganese as well as sulfate quantity by the formula V1S= V2S2.

5. H2SO4+ Mn2O7 net ionic equation

The net ionic equation between H2SO4 + Mn2O7 is as follows,

14H+ + 7SO42- + 2Mn2+ + 7O2- = 2Mn2+ + 7SO42- + H+ + OH

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 Mn2O7 also dissociates to Mn2+ ion and O2-.
  • After that, the product Mn2(SO4)7 also dissociates to Mn2+ which is d5 stable configuration and corresponding SO42-.
  • Water is also ionized to H+ and OH-.

6. H2SO4+ Mn2O7 conjugate pairs

H2SO4 + Mn2O7 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 Mn2O7 intermolecular forces

The intermolecular force between H2SO4 is an electrostatic, covalent force. For Mn2O7, it is ionic interaction, and peroxy linkage is present. In Mn2(SO4)7, strong ionic interactions are present along with dipole force and for water, H-bonding is present.

MoleculeActing
force
H2SO4Electrostatic,
van der waal’s
Dipole
interaction
Mn2O7Ionic, peroxy
linkage,
and
electrostatic
Mn2(SO4)7Coulombic force,
strong ionic
interaction,
metallic bond
H2OCovalent,
H-bonding
Intermolecular Forces

8. H2SO4 + Mn2O7 reaction enthalpy

H2SO4 + Mn2O7  reaction enthalpy is -5428 KJ/mol which can be obtained by the formula enthalpy of products – enthalpy of reactants, and here the change in enthalpy is negative.

MoleculeEnthalpy
(KJ/mol)
Mn2O7-726
H2SO4-814
Mn2(SO4)7-520
H2O-68
Enthalpy of Reactants
and Products

9. Is H2SO4 + Mn2O7 a buffer solution?

The reaction between H2SO4 + Mn2O7 gives a buffer solution and they can control the pH of the solution.

10. Is H2SO4 + Mn2O7 a complete reaction?

The reaction between H2SO4 + Mn2Ois a complete reaction because it gives one complete product Mn2(SO4)along with the water molecule.

11. Is H2SO4 + Mn2O7 an exothermic or endothermic reaction?

The reaction H2SO4 + Mn2O7 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 + Mn2O7 a redox reaction?

The reaction between H2SO4 + Mn2O7 is a redox reaction because in this reaction many elements get reduced and oxidized. Here, Mn gets reduced and S gets oxidized.

Redox Schematic of the
H2SO4 and Mn2O7 Reaction

13. Is H2SO4 + Mn2O7 a precipitation reaction

The reaction H2SO4 + Mn2O7 is a precipitation reaction because Mn2(SO4)7 gets precipitated in the solution and is not a soluble in the reaction mixture.

14. Is H2SO4 + Mn2O7 reversible or irreversible reaction?

The reaction between H2SO4+ Mn2O7 is irreversible because we get Mn2(SO4)7 as a major product and the equilibrium of the reaction is shifted toward right hand side. Also, we can say the reaction goes to the forward direction only.

15. Is H2SO4 + Mn2O7 displacement reaction?

The reaction between H2SO4+ Mn2O7 is an example of a double displacement reaction because in the above reaction Mn displaced  H+ in H2SO4 and H+ also displaced Mn from Mn2O7.

Double Displacement Reaction

Conclusion

H2SO4 and Mn2O7 reaction mainly gives us Mn2(SO4)7 along with water molecule. So, using this reaction we can produce manganese sulfate, and Mn2O7 acts as strong oxidising agent here.

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