15 Facts on H2SO4 + KI: What, How to Balance & FAQs

H₂SO₄ (Sulphuric acid) is the strong acid and KI (Potassium iodide) is a white crystalline powder. Let us know some facts about the H₂SO₄ + KI.

Sulphuric acid is also known as oil of vitriol. It is colorless, odorless viscous liquid. Potassium iodide composed with the elements Potassium and Iodine. It is an ionic compound.

In this article we will discuss about the reaction between Sulphuric acid and Potassium Iodide, balancing of equation, type of reaction and net ionic equation of the reaction.

What is the product of H₂SO₄ and KI

Potassium bisulfate (KHSO₄), Iodine (I₂), Sulfur dioxide (SO₂) and Water (H₂O) are produced in the reaction between Sulphuric acid and potassium iodide.

3H₂SO₄ + 2KI = 2KHSO₄ + I₂ + SO₂ + 2H₂O

What type of reaction is H₂SO₄ + KI

H₂SO₄ + KI is a redox reaction.

How to balance H₂SO₄ + KI

The reaction H₂SO₄ + KI is balanced using following steps-

H₂SO₄ + KI = KHSO₄ + I₂ + SO₂ + H₂O

• The number of atoms present on both sides is counted which should be the same.

• The number of Oxygen atoms of both the sides of the reaction balance by adding coefficient 3 to the Sulphuric acid molecule at the reactant side.
• 3H₂SO₄ + KI = KHSO₄ + I₂ + SO₂ + H₂O
• The number of Hydrogen atoms of both sides of the reaction balance by adding coefficient 2 to the Water molecule at product side.
• 3H₂SO₄ + KI = KHSO₄ +I₂ + SO₂ + 2H₂O
• The number of Suphur atoms of both sides of the reaction balance by adding coefficient 2 to the Potassium bisulfate molecule at product side.
• 3H₂SO₄ + KI = 2KHSO₄ + I₂ + SO₂ + 2H₂O
• The number of Iodine atoms of both sides of the reaction balance by adding coefficient 2 to the Potassium iodide molecule at reactant side.
• 3H₂SO₄ + 2KI = 2KHSO₄ + I₂ + SO₂ + 2H₂O
• So the balanced chemical reaction is:
• 3H₂SO₄ + 2KI = 2KHSO₄ + I₂ + SO₂ + 2H₂O

H₂SO₄ + KI Titration

H₂SO₄ + KI do not undergo titration because there is no equivalence point.

H₂SO₄ + KI net ionic equation

The net ionic equation for the reaction H₂SO₄ + KI is

6H⁺ + SO₄^2- = 2H⁺ + SO₂ + 2H₂O

This net ionic equation is derived using the steps mentioned below

• The balanced equation with phases for H₂SO₄ + KI
• 3H₂SO₄(aq) + 2KI(aq) = 2KHSO₄(aq) + I₂(aq) + SO₂(g) + 2H₂O(l)
• Then the equation written in splitting of compounds
• 6H⁺+3SO₄^2- + 2K⁺ + 2I^– = 2K⁺ + 2H⁺ + 2SO₄^2- +  2I^– + SO₂ + 2H₂O
• The net ionic equation is as follows by removing the spectator ions (ions that are same both on reactant and product sides)
• 6H⁺ + SO₄^2- = 2H⁺ + SO₂ + 2H₂O

H₂SO₄ + KI conjugate pairs

The conjugate pairs of H₂SO₄ + KI are as follows:

• The conjugate base of H₂SO₄ is SO₄^2-
• The conjugate base of KI is I^–

H₂SO₄ and KI Intermolecular forces

Intermolecular forces present in H₂SO₄ + KBr are as follows:

• Hydogen bonding, dipole-dipole interaction and Van der Waals dispersion are the intermolecular forces in H₂SO₄.
• Potassium iodide is ionicaly bonded to each other.

H₂SO₄ + KI reaction enthalpy

The reaction enthalpy of H₂SO₄ + KI is -439.68 KJ/mol.

• The standard enthalpy of a reaction is calculated using the formula:
• ΔH⁰_{f (reaction)} = ΣΔH⁰_{f (product)} – ΣΔH⁰_{f (reactants)}
• Thus, Enthalpy change = [2*(-1163.3) + 1*(62.42) + 1*(-296.9) + 2*(-285.82)] – [3*(-814.0) + 2*(-125.52)]
• = [(-3132.72) – (-2693.04)] KJ/mol
• = -439.68 KJ/mol

Is H₂SO₄ + KI a buffer solution

H₂SO₄ + KI reaction will not form a buffer solution because Sulphuric acid (H₂SO₄) is a strong acid and there can only be present a weak acid or base in buffer solution.

Is H₂SO₄ + KI a complete reaction

H₂SO₄ + KI is a complete reaction and the products like Potassium hydrogen sulphate, Iodine, sulphur dioxide and water are formed after completion of the reaction.

Is H₂SO₄ + KI an exothermic or endothermic reaction

H₂SO₄ + KI is an exothermic reaction because it shows negative enthalpy -439.68 KJ/mol.

Is H₂SO₄ + KI a redox reaction

H₂SO₄ + KI is a redox reaction due to change in oxidation state of sulphur and Iodine ions on reactant and product side.

3H₂S⁶⁺O₄ + 2KI^1- = 2KHSO₄ +I₂⁰ + S⁴⁺O₂ + 2H₂O

Is H₂SO₄ + KI a precipitation reaction

H₂SO₄ + KI reaction is not a precipitation reaction because no precipitate is formed during the reaction.

Is H₂SO₄ + KI a reversible or irreversible reaction

H₂SO₄ + KI is an irreversible reaction because the products formed do not react to give back reactants under the same condition.

Is H₂SO₄ + KI a displacement reaction

H₂SO₄ + KI is a Single displacement reaction, in which sulphate ion is displaced from H₂SO₄ molecule to form Potassium hydrogen sulfate.

3H₂SO₄ + 2KI = 2KHSO₄ + I₂ + SO₂ + 2H₂O

Conclusion

When Sulphuric acid reacts with Potassium iodide it produces Potassium bisulfate, Iodine, sulfur dioxide and water. It is a single displacement reaction, also the redox reaction. It has negative reaction enthalpy hence it is exothermic reaction.