17 Facts on HCl + H2SO4 : What, How To Balance & FAQs

HCl is a strong acid called hydrogen chloride, so it can easily react with a strong acid like H₂SO₄. Let us see the details of the reaction between HCl and H₂SO₄.

HCl is a strong acid which undergo oxidation to generate Cl₂, or a combination of partially oxidised products may be formed. The concentration of H₂SO₄ which is strong acid determine the strength of the reaction and the degree of oxidation. At higher concentrations formation of more oxyacids of chlorine will be more.

In this article titration, intermolecular forces, reaction enthalpy and nature of reaction etc. are explained.

What is the product of HCl and H₂SO₄

The products of HCl + H₂SO₄ are HCl gas, aqueous H₂SO₄ and Chlorosulfuric acid.

HCl(aq)+H₂SO₄(conc) = HCl(g)+H₂SO₄(aq)

HCl (aq) + H₂SO₄ (aq) = HSO₃Cl (l) + H₂O (l)

What type of reaction is HCl + H₂SO₄

HCl +H₂SO₄ is an acid base and dehydration reaction.

How to balance HCl + H₂SO₄

The reaction between HCl and H₂SO₄ is balanced using the following steps.

HCl(aq)+H₂SO₄(conc) = HCl(g)+H₂SO₄(aq)

HCl (aq) + H₂SO₄ (aq) = HSO₃Cl (l) + H₂O (l)

• Label the reactants and products by required number of alphabets like A,B,C,D.
• Now reaction reduces to,        
•  A HCl + B H₂SO₄= C HSO₃Cl + D H₂O
• Equate all reaction coefficients for all elements that are of the same type by rearranging them.
• When we compare the stoichiometric proportions and coefficients of all the elements in this reaction, we obtain,

• Gaussian elimination is used to calculate the coefficient values.
• A = 1, B = 1, C = 1, D = 1
• Thus the balanced equation is-
• HCl + H₂SO₄ =  HSO₃Cl+  2H₂O

HCl + H₂SO₄ titration

HCl + H₂SO₄ titration do not take place because HCl and H₂SO₄ both are strong acids.

H₂SO₄ + HCl net ionic equation

The net ionic equation for H₂SO₄ + HCl chemical reaction is-

HCl (aq) + H₂SO₄ (aq) → HSO₃Cl (aq) + H₂O (l)

H⁺ + Cl^–  + OH^– + SO₃^2-    → H⁺ + SO₃^2-  + H₂O

To derive these net ionic equations following steps are used.

• Cancel out the similar ions from both the LHS and RHS, and we get,
• OH^– + H+  → H₂O
• The H⁺ and SO₃^2- ions get canceled on both sides, so net ionic equation become
• H⁺ + Cl^–  + OH^– + SO₃^2-    → H⁺ + SO₃^2-  + OH^–

HCl + H2SO4 conjugate pairs

The conjugate pairs of H₂SO₄ + HCl are given below:

• H₂SO₄ donates its proton and acts as a conjugate base by forming HSO₄^– ion.
• HCl donates an electron and acts as a conjugate base by forming Cl^–.

HCl and H₂SO₄ intermolecular forces

The intermolecular forces of HCl and H₂SO₄ are-

• In H₂SO₄, hydrogen bonding is the intermolecular forces that bind the hydrogen and sulphite ions together.
• In HCl, strong ionic attractive forces exist between the cation H⁺ and anion Cl^–, as hydrogen chloride is an ionic compound.

HCl + H₂SO₄ reaction enthalpy

The reaction enthalpy for H₂SO₄ + HCl is –576.46 kJ/mol, where-

• The enthalpy of the formation of H₂SO₄ is -814 kJ/mol.
• The enthalpy of the formation of HCl is -167.16 kJ/mol.
• The enthalpy of the formation of HSO₃Cl is -118.9 kJ/mol.
• The enthalpy of the formation of H₂O is -285.8 kJ/mol.
• The Reaction enthalpy (∆H) of H₂SO₄ + HCl = Enthalpy of product – enthalpy of reactant, we get,
• (∆H) of H₂SO₄ + HCl is = -981.16 kJ/mol – (-404.7) kJ/mol
• (∆H) of H₂SO₄ + HCl is = -576.46 kJ/mol.

Is HCl + H₂SO₄ a buffer solution

HCl + H₂SO₄ is not a buffer solution, because both H₂SO₄ and HCl are strong acids and thus not able to form a buffer solution.

Is HCl + H₂SO₄ a complete reaction

H₂SO₄ + HCl is a complete reaction, because both the reactants are strong acids, and dissolve in the solution due to its strong dissociation.

Is HCl + H₂SO₄ an exothermic or endothermic reaction

HCl + H₂SO₄ is an exothermic reaction because heat is released to the environment during the dilution of sulfuric acid.

Is HCl + H₂SO₄ a redox reaction

HCl + H₂SO₄ is a redox reaction, where HCl is oxidised to HSO₃Cl and H₂SO₄ is reduced to HSO₃Cl.

Is HCl + H₂SO₄ a precipitation reaction

HCl + H₂SO₄ is not a precipitation reaction because the products formed are HCl gas, aquous H₂SO₄ and Chlorosulfuric acid which is soluble in liquid.

Is HCl + H₂SO₄ reversible or irreversible reaction

HCl + H₂SO₄ is an irreversible reaction because the affinity of H₂SO₄ to attract H₂O from aqueous HCl is more as compared to HCl itself.

Is HCl + H₂SO₄ displacement reaction

HCl + H₂SO₄ is a displacement reaction because H₂SO₄ is more reactive than HCl, so displaces Cl.

What is the mixture name of HCl and H₂SO₄

HCl and H₂SO₄ form the mixture of Chlorosulfuric acid.

Which one is stronger between HCl and H₂SO₄

HCl reacts as a strong acid because compared to HCl, the HSO₄^– anion has a much lower ability to split into H⁺ and SO₄^2-. H₂SO₄ pKa is 3.0 and HCl is reported to be 6.3, therefore the dissociation constant for HCl is greater than that of H₂SO₄.

Conclusion:

H₂SO₄ + HCl is a displacement reaction reaction has the products HSO₃Cl and H₂O. Sulphuric acid is preferred over hydrochloric acid because this acid is universally used for a variety of neutralization reactions. Sulphuric acid is more potent than all other acids and is also simpler and safer to use.