The Chemistry Behind H2SO4 + Cl2: 13 Facts You Should Know

Sulfuric acid (H₂SO₄) is a powerful mineral acid, and Cl₂ is a diatomic gaseous molecule. Let us explore more about their reaction.

Sulfuric acid is also known as the oil of vitriol. The central atom sulfur is in +6 oxidation state here. It is a highly viscous hygroscopic liquid having a density of 1.8302g/cm³. At room temperature, Cl₂ appears to be a greenish-yellow gas with a pungent odor. It is oxidizing in nature.

In this article, we will discuss some important properties and parameters of the reaction H₂SO₄ + Cl₂.

What is the product of H₂SO₄ and Cl₂?

Sulfur dioxide (SO₂), perchloric acid (HClO₄) and H₂O are the products of the reaction H₂SO₄ + Cl₂.

H₂SO₄(aq) + Cl₂(g)→ HClO₄ + SO₂(g) + H₂O

What type of reaction is H₂SO₄ + Cl₂?

The reaction H₂SO₄ + Cl₂ is an oxidation-reduction reaction.

How to balance H₂SO₄ + Cl₂?

To balance the H₂SO₄ + Cl₂ reaction, the following steps are to be followed.

H₂SO₄ + Cl₂ → HClO₄ + SO₂ + H₂O

• Count the number of atoms present on the reactant side and on the product side.

• Multiply with significant numbers to the specific reactants and products such that the number of each atom on the reactant side and the product side becomes equal.
• 7× H₂SO₄ on reactant side and 6×H₂O, 7 × SO₂ and 2×HClO₄ on the product side.
• Count the number of atoms after the multiplication process to ensure an equal number of atoms on both sides.

• Thus the balanced chemical equation is
• Cl₂ + 7H₂SO₄  = 2HClO₄ + 7 SO₂ + 6H₂O

H₂SO₄ + Cl₂ titration

Titration is not possible in the reaction H₂SO₄ + Cl₂, because H₂SO₄ is a very strong acid and Chlorine is a gas at room temperature.

H₂SO₄ + Cl₂ net ionic equation

The net ionic equation of the reaction is-

Cl_2(g) + 12H⁺_(aq)+ 7SO₄^2- _(aq) = 2ClO₄^– _(aq)+ 7 SO_2(g) + 6H₂O

The net ionic equation is obtained by using the steps below.

• Write the balanced chemical reaction
• Cl₂ + 7H₂SO₄ = 2HClO₄ + 7 SO₂ + 6H₂O
• H₂SO₄ and HClO₄ dissociates in aqueous media as:
• H₂SO₄ = 2H⁺_(aq) + SO₄^2- _(aq) and HClO₄ = H⁺ _(aq)+ ClO₄^–_(aq).
• So, the complete ionic equation is
• Cl_2(g) + 14H⁺(_aq)+ 7SO₄^2- _(aq) = 2H⁺ _(aq)+ 2ClO₄^– _(aq)+ 7 SO_2(g) + 6H₂O       
• 2H⁺ gets canceled out from both sides.
• Thus the net ionic equation is
• Cl₂(g) + 12H⁺(aq)+ 7SO₄^2- (aq) → 2ClO₄^– (aq)+ 7 SO₂(g) + 6H₂O

H₂SO₄ + Cl₂ conjugate pairs

The conjugate pairs of H₂SO₄ + Cl₂ reaction are:

H₂SO₄ and Cl₂ intermolecular forces

The intermolecular forces of H₂SO₄ + Cl₂ reaction are:

• H₂SO₄ molecule has Hydrogen bonding tendency, dipole-dipole interaction and Dispersion forces.
• Cl₂ has London dispersion force as it is a nonpolar molecule.
• HClO₄ possesses dipole–dipole force.
• H₂O participates in hydrogen bonding, dipole-induced dipole interactions.
• SO₂ shows dipole-dipole interaction as it is a polar molecule.

Is H₂SO₄ + Cl₂ a buffer solution?

H₂SO₄ + Cl₂ is not a buffer solution because sulfuric acid is a very strong acid and does not constitute a buffer solution.

Is H₂SO₄ + Cl₂ a complete reaction?

The H₂SO₄ + Cl₂ reaction is not a complete reaction. Because the so-formed product SO₂ can react with Cl₂ gas further (if provided in excess) to form SO₂Cl₂ which can react with H₂O to form H₂SO₄ and HCl.

• SO₂  + Cl₂ → SO₂Cl₂
• SO₂Cl₂ + H₂O →H₂SO₄ + HCl

Is H₂SO₄ + Cl₂ a redox reaction?

The H₂SO₄ + Cl₂ reaction is a redox reaction. Here, Sulfur gets reduced from +6 to +4 oxidation state, and chlorine gets oxidized from 0 to +7 oxidation state.

Is H₂SO₄ + Cl₂ a precipitation reaction?

The reaction of H₂SO₄ + Cl₂ is not a precipitation reaction as no precipitate is formed in the reaction mixture.

Is H₂SO₄ + Cl₂ reversible or irreversible reaction?

The H₂SO₄ + Cl₂ is an irreversible reaction because of the formation of gaseous product SO₂(g), which will not participate in the reverse reaction. And also, the forward reaction is thermodynamically more favorable due to release of SO₂(g), so no question of being reversible arises.

Is H₂SO₄ + Cl₂ displacement reaction?

The H₂SO₄ + Cl₂ reaction is not a displacement reaction as no ion displacement takes place.

Conclusion

The sodium salt of Perchloric acid named sodium perchlorate (NaClO₄) is used as rocket fuel. Chlorine-containing compounds are used as bleaching agent and sulfuric acid is an essential component of every laboratories.

Soumak Mahato

Hello….I am Soumak Mahato. I have completed my M.Sc in Chemistry from Banaras Hindu University in 2022, specializing in Inorganic Chemistry. I have joined Lambdageeks as an SME in Chemistry. Trying to explain chemistry in easy way. My hobbies include Sports and music.
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