15 Facts on HCl + K2SO4: What, How To Balance & FAQs

Potassium sulfate, an inorganic salt, tends to react with strong acids such as Hydrochloric acid. Let us look into how their reaction occurs.

Hydrochloric acid (HCl) is a strong acid for it can completely dissociate in water, and is a colorless solution with a pungent odor. Its physical properties vary with concentration. Potassium sulfate (K2SO4) is a water-soluble white crystalline solid that, when reacted with HCl, forms an alkali metal salt and an acid.

Let us go through the products of the reaction between HCl and K2SO4, the enthalpy of the reaction, the reaction type, and so on in depth in the following sections.

What is the product of HCl and K2SO4

HCl and K2SO4 are reacted to form Sulfuric acid and Potassium chloride respectively. The chemical reaction is as follows:

2HCl (aq) + K2SO4 (aq) = H2SO4 (aq) + 2KCl (aq)

What type of reaction is HCl + K2SO4

K2SO4 with HCl is a Double displacement (Metathesis) reaction.

How to balance HCl + K2SO4

The skeletal unbalanced chemical equation is: HCl + K2SO4 = H2SO4 + KCl

The following are the steps to equate the reaction mentioned above:

  • The number of atoms of elements present on both the reactant and product sides must be equal for the reaction to be balanced.
AtomsReactant SideProduct Side
Hydrogen1 2
Potassium2  1
Table showing the count of Atoms from the unbalanced chemical equation
  • According to the preceding table, the only unbalanced atoms in this reaction are K and H. Stoichiometric coefficients are added to molecules as needed.
  • Here, the compounds containing chlorine, i.e., HCl and KCl, are multiplied by coefficient 2, balancing the whole chemical equation.
  • The balanced chemical reaction is:

2HCl + K2SO4 = H2SO4 + 2KCl

HCl + K2SO4 Titration

K2SO4 cannot be titrated against HCl because no significant color change will be detected even when an indicator such as Phenolphthalein or Methyl orange is used. It is considered a neutral salt that is colorless in an acidic solution.

HCl + K2SO4 Net Ionic Equation

  • The complete ionic equation for HCl + K2SO4 is as follows:

2K+ (aq) + SO42- (aq) + 2H+ (aq) + 2Cl (aq) = 2K+ (aq) + 2Cl (aq) + 2H+ (aq) + SO42- (aq)

  • However, the net ionic equation comprises only those species that are taking part in the reaction, eliminating the spectator ions; as all of the ions are spectator ions in the reaction between HCl and K2SO4, thus, there is no reaction.

HCl + K2SO4 Conjugate Pairs

  • The conjugate base of HCl is Cl as HCl being a strong acid, donates a proton to form a Cl ion.
  • SO42- is a weak base that accepts a proton (H+) to form its conjugate acid HSO42-.

HCl + K2SO4 Intermolecular Forces

  • The Intermolecular forces observed in HCl are dipole-dipole interaction and London dispersion forces, with dipole-dipole interactions being stronger. K2SO4 is composed of ions hence the intermolecular forces of attraction present in K2SO4 are ionic forces.
  • For the products formed, H2SO4 shows the presence of Van der waals dispersion forces, dipole-dipole interactions and strong intermolecular hydrogen bonding forces. The intermolecular interaction in KCl is ionic forces.
Intermolecular Hydrogen bonding in H2SO4

HCl + K2SO4 Reaction Enthalpy

The Enthalpy of the reaction between K2SO4 and HCl is evaluated as 95.1 kJ/mol.

Compounds (aq.)Bond Enthalpy, ΔH⁰f (kJ/mol)
Enthalpy values of reactants and products

The Reaction enthalpy is calculated using the formula: ΔH⁰f (reaction) = ΣΔH⁰f (products) ΣΔH⁰f (reactants)

Is HCl + K2SO4 a Buffer Solution

The reaction HCl + K2SO4 does not behave as a buffer because of the presence of a strong acid, and secondly, KCl obtained as a product is a salt of strong acid, so a noticeable pH change would be observed.

Is HCl + K2SO4 a Complete Reaction

HCl + K2SO4 is a complete reaction as both the products formed are completely ionized and are soluble in water; thereby, it will not undergo any further reactions.

Is HCl + K2SO4 an Exothermic or Endothermic Reaction

The reaction HCl + K2SO4 is an endothermic reaction due to its positive enthalpy change. As a result, a considerable amount of energy is absorbed to carry out the reaction.

Is HCl + K2SO4 a Redox Reaction

HCl + K2SO4 is not a redox reaction since no change in oxidation state is observed for any of the reacting atoms of elements.

Is HCl + K2SO4 a Precipitation Reaction

K2SO4 with HCl is not a precipitation reaction since both products formed after completion of the reaction are highly soluble in water, so no precipitate will develop.

Is HCl + K2SO4 Reversible or Irreversible Reaction

HCl + K2SO4 reaction is irreversible in nature because the products formed cannot react again to give back the reactants under the same conditions.

Is HCl + K2SO4 Displacement Reaction

The reaction of K2SO4 with HCl occurs via Displacement. The reaction mechanism it undergoes is an example of Double displacement (metathesis) reaction wherein the reactant ions exchange with each other to generate two new compounds.

Double Displacement reaction


HCl and K2SO4 both function as significant laboratory reagents. K2SO4 is a powerful electrolyte that reacts with HCl to give KCl and H2SO4. KCl is used in agricultural fertilizer manufacture. It is also used in water softener units and in the making of soaps. H2SO4 is a vital catalyst in the chemical industry.

Padmakshi Kotoky

Hello, I am Padmakshi Kotoky working as a Subject Matter Expert on this platform. I have completed my post-graduation from the Institute of Chemical Technology, Mumbai. I have always found Chemistry an intriguing subject and enjoy exploring more on it. I would like to utilize this platform to explain the subject in an easy and precise manner making it simpler for the readers to understand the concepts with clarity. I engage myself in Singing, Dancing, and nature photography during my leisure time. Let's connect through LinkedIn - https://www.linkedin.com/in/padmakshi-k-b54679132