H2SO4 is a strong acid and it can react with many more transition metals. Let us see the mechanism behind the reaction H2SO4 + Fe.
Iron is placed higher postion in electrochemical series than hydrogen, so it has higher reduction potential. Sulfuric acid is one of strong mineral inorganic acids and also a powerful oxidizing agent. Sulfuric acid has a greater affinity with water molecule and produce heat when it reacts with water.
To estimate the quantity of iron we can perform the reaction between Fe and H2SO4 or estimate the quantity of sulfate also. 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 Fe?
Ferrous sulfate is a major product formed when H2SO4 and Fe are reacted together and hydrogen gas is liberated. Fe is present in a higher position than hydrogen in the electrochemical series so the corresponding sulfate is formed.
2. What type of reaction is H2SO4 + Fe?
H2SO4 + Fe reaction is an example of a single displacement reaction along with redox and precipitation reactions. Here higher reduction potential element reacted with the acid molecule.
3. How to balance H2SO4 + Fe?
H2SO4 + Fe = FeSO4 + H2 this reaction is not balanced by the oxidation number because iron shows different valency which is not equal for the left side and right side. 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, and D as there are only four molecules obtained for this reaction and the reaction looks like: A H2SO4 + B Fe = C FeSO4 + D H2
- 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 = 2D, S = A = C, O = 4A = 4C, Fe = B = C
- Step 3 – Using Gaussian elimination to determine the coefficient values
- Using the Gaussian elimination and equating all the equations we get, A = 1, B = 1, C = 1, and D = 1, so the oxidation number of Fe is +2 on both sides.
- Step 4- now write the whole equation in the balanced form
- The overall balanced equation will be,
H2SO4 + Fe = FeSO4 + H2
4. H2SO4 + Fe titration
To estimate the quantity of sulfur or copper, we can perform a titration between Fe and H2SO4
Apparatus used
We need a burette, conical flask, burette holder, volumetric flask, and beakers for this titration.
Titre and titrant
H2SO4 versus Fe, H2SO4 acts as a titrant which is taken in the burette and the molecule to be analyzed is Fe which is taken in a conical flask.
Indicator
The whole titration is done in an acidic medium or acidic pH so the best suitable indicator will be phenolphthalein which gives perfect results for this titration at given pH.
Procedure
The burette was filled with standardized H2SO4 and Fe 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 indicator changes its color and the reaction was done.
We repeat the titration several times for better results and then we estimate the iron as well as sulfate quantity by the formula V1S1 = V2S2.
5. H2SO4+ Fe net ionic equation
The net ionic equation between H2SO4 + Fe is as follows,
2H+ + SO42- + Fe2+ + 2e– = Fe2+ + SO42- + H2
6. H2SO4+ Fe conjugate pairs
In the reaction, H2SO4 + Fe 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 H– = H2
7. H2SO4 and Fe intermolecular forces
The intermolecular force present in H2SO4 is due to the strong electrostatic force between proton and sulfate ions. Also due to polarity, van der waal’s attraction is present but in the case of H2, covalent force, as well as dipole interaction is present, and for FeSO4 only covalent force is present.
| Molecule | Acting force |
| H2SO4 | Electrostatic, van der waal’s Dipole interaction |
| Fe | Covalent, metallic bond |
| FeSO4 | Columbia force, ionic interaction |
| H2 | Covalent, H-bonding |
8. H2SO4 + Fe reaction enthalpy
In the reaction, H2SO4 + Fe reaction enthalpy is,+131.34 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) |
| Fe | 0 |
| H2SO4 | -814 |
| FeSO4 | -924.66 |
| H2 | +242 |
and Products
9. Is H2SO4 + Fe a buffer solution?
The reaction between H2SO4 + Fe gives a buffer solution of FeSO4 and H2 and they can control the pH of the reaction.
10. Is H2SO4 + Fe a complete reaction?
The reaction H2SO4 + Fe is the complete reaction because it gives one complete product FeSO4 along with H2 gas. The reaction takes need some time to complete until all the reactants completely reacted the products are not formed.
11. Is H2SO4 + Fe an exothermic or endothermic reaction?
The reaction H2SO4 + Fe is endothermic in terms of thermodynamics first law. So, the reaction takes more energy and temperature from the surroundings which help to complete the reaction, Where δH is always positive.
12. Is H2SO4 + Fe a redox reaction?
H2SO4 + Fe reaction is a redox reaction because in this reaction many elements get reduced and oxidized as hydrogen gets reduced and Fe gets oxidized.
H2SO4 and Fe Reaction
13. Is H2SO4 + Fe a precipitation reaction
The reaction H2SO4 + Fe is a precipitation reaction because FeSO4 gets precipitated in the solution and is not soluble in the reaction mixture.
14. Is H2SO4 + Fe reversible or irreversible reaction?
The reaction between H2SO4+ Fe is irreversible because we get H2 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 + Fe displacement reaction?
The reaction between H2SO4+ Fe is an example single displacement reaction because in the above reaction Fe2+ displaced H+ in H2SO4 only and H2 gas becomes free from the reaction.
Conclusion
H2SO4 and Fe reaction mainly gives us ferrous sulfide along with hydrogen gas so it is a commercially important reaction for the production of hydrogen gas. Also, the quantitative analysis of the H2SO4 and Fe gives the amount of iron as well as sulfate in the respective sample.
Read more facts on H2SO4:
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.