15 Facts on H2SO4 + Fe2O3: What, How To Balance & FAQs

Fe₂O₃ (Ferric oxide), found as hematite ore, is an insoluble solid, and H₂SO₄ (Sulfuric acid) is a strong inorganic acid. Let us study how their reaction occurs.

The reaction of H₂SO₄ with Fe₂O₃ is an acid-base reaction. H₂SO₄ is highly corrosive and a powerful dehydrating agent that is highly useful in organic synthesis. Fe₂O₃ is red-brown in appearance and a stable oxide of iron.

Here, we will discuss some reaction parameters like enthalpy, molecular forces, and the feasibility of the H₂SO₄+Fe₂O₃ reaction.

What is the product of H₂SO₄ and Fe₂O₃

Fe₂(SO₄)₃ (Ferric sulfate) and H₂O (water molecules) are produced in the reaction of H₂SO₄ + Fe₂O₃.

H₂SO₄ + Fe₂O₃ → Fe₂(SO₄)₃ + H₂O

What type of reaction is H₂SO₄ + Fe₂O₃

H₂SO₄ + Fe₂O₃ is a neutralization reaction. Here, Fe₂O₃ is a base that neutralizes sulfuric acid and forms salt.

How to balance H₂SO₄ + Fe₂O₃

The H₂SO₄ + Fe₂O₃ reaction is balanced using the following steps.

H₂SO₄ + Fe₂O₃ → Fe₂(SO₄)₃ + H₂O

• The reactants and the products involved in the reaction are identified and counted.
• With the use of coefficients, the charges and elements are balanced. Before H₂SO₄ and H₂O, a coefficient of 3 is added.
• Thus we get the balanced equation as
• 3H₂SO₄ + Fe₂O₃ → Fe₂(SO₄)₃ + 3H₂O

H₂SO₄ + Fe₂O₃ titration

Gravimetric analysis is used for the titration of Fe₂O₃. It is a type of analytical method in which the estimation of the analyte is done by the mass of the solid which is carried out using the following process.

Apparatus

Crucible, burette, glass rod, funnel, beaker, filter paper, burner

Procedure

• Burette is filled with Ferrous ammonium sulfate solution. From this, 10 ml of the sulfate solution is taken into the volumetric flask and diluted with distilled water up to the mark.
• The resultant solution is transferred to a dry beaker to get the homogenous solution.
• 25 ml of the diluted solution is taken in another beaker and 50 ml of distilled water is added to it with the help of a cylinder.
• After the addition of 5 ml of H₂SO₄ to the solution, heat it on the burner using a wire gauge.
• 3 ml of nitric acid (HNO₃) is added dropwise to the heating solution with constant stirring. HNO₃ will oxidize Iron and the color of the solution changes to yellow.
• 0.2 grams of NH₄Cl (ammonium chloride) is further added to the heated solution along with 10 ml of 1:1 ammonia solution until the reddish brown precipitate of Fe(OH)₃ appears.
• The solution is heated to get the precipitate to settle down and boil off the excess of ammonia.
• Filter the solution using Whatman paper and transfer the precipitate carefully to the filter paper.
• Precipitate is washed with 2% ammonium nitrate solution and hot water and the precipitate is dried and heated strongly in the crucible.
• Weight of the dried precipitate (Fe₂O₃) is taken and used in calculations for the estimation of the Iron.

H₂SO₄ + Fe₂O₃ net ionic equation

The net ion equation of the H₂SO₄ + Fe₂O₃ reaction is

Fe₂O₃(s) + 2H⁺(aq) → 2Fe³⁺(aq)+ 2SO₄^2-(aq) + 3H₂O(l)

The ionic equation is deduced using the following steps

• The balanced equation for Fe₂O₃ + H₂SO₄ is written in the first step,
• Fe₂O₃ + H₂SO₄ → Fe₂(SO₄)₃ + 3H₂O
• The phases (solid, gas, liquid, or aqueous) is indicated for all the substituents.
• Fe₂O₃(s) + H₂SO₄(aq) → Fe₂(SO₄)₃(aq) + 3H₂O(l)
• Splitting of the strong-electrolytes is done in the next step. Since Fe₂O₃ is solid and H₂O is a weak-electrolyte, they will not split. The equation now becomes,
• Fe₂O₃(s) + 2H⁺(aq)+SO₄^2-(aq) → 2Fe³⁺(aq)+ 3SO₄^2-(aq) + 3H₂O(l)
• The spectator-ions are canceled out and the net equation is
• Fe₂O₃(s) + 2H⁺(aq) → 2Fe³⁺(aq)+ 2SO₄^2-(aq) + 3H₂O(l)

H₂SO₄ + Fe₂O₃ conjugate pairs

H₂SO₄ + Fe₂O₃ will not constitute a conjugate acid-base pair as they do not conjugate with each other.

• The conjugate base of H₂SO₄ is SO₄^2-.

• Fe₂O₃ is an oxide so no conjugate pair concept is applied here.

H₂SO₄ and Fe₂O₃ intermolecular forces

• Hydrogen bonding, dipole-dipole interactions and dispersion forces are observed in H₂SO₄ molecules where Hydrogen bonding is most prominent.
• Electrostatic force of attraction is found in Fe₂O₃ molecules as it is ionic in nature attributed to the small size of Fe³⁺ ion and electronegativity difference between Fe and O.

H₂SO₄ + Fe₂O₃ reaction enthalpy

H₂SO₄ + Fe₂O₃ reaction enthalpy is -59.68 KJ/mol. The calculation of the enthalpy is done using the values below,

∆H_f^°(reaction) = ∆H_f^°(products) – ∆H_f^°(reactants)

= -3620.8 – (-3561.12)

= -59.68 KJ/mol

Is H₂SO₄ + Fe₂O₃ a buffer solution

Fe₂O₃ + H₂SO₄ will not function as a buffer as here sulfuric acid is used which is a strong acid.

Is H₂SO₄ + Fe₂O₃ a complete reaction

Fe₂O₃ + H₂SO₄ is a complete reaction as a complete neutralization is observed by giving off the salt Fe₂(SO₄)₃ and water as the products. 

Is H₂SO₄ + Fe₂O₃ an exothermic or endothermic reaction

Fe₂O₃ + H₂SO₄ is an exothermic reaction as it gives off heat during the reaction. Also, the negative value of enthalpy (-59.68 KJ/mol) indicates the same.

Is H₂SO₄ + Fe₂O₃ a redox reaction

Fe₂O₃ + H₂SO₄ is not a redox reaction because the oxidation of the substituents remains same throughout the reaction.

Is H₂SO₄ + Fe₂O₃ a precipitation reaction

H₂SO₄ + Fe₂O₃ is not a precipitation reaction as the salt formed [Fe₂(SO₄)₃] is soluble in water.

Is H₂SO₄ + Fe₂O₃ reversible or irreversible reaction

H₂SO₄ + Fe₂O₃ reaction is an irreversible reaction as the Iron sulfate formed will not react with water to give the reactants due to the lesser reactivity of hydrogen than Fe.

Is H₂SO₄ + Fe₂O₃ displacement reaction

H₂SO₄ + Fe₂O₃ is a double displacement reaction.

Conclusion

The reaction between H₂SO₄ and Fe₂O₃ is exothermic and occurs in an irreversible manner. Fe₂O₃ is a major source for the production of iron and is of high importance when it comes to dye and cosmetic industry.