15 Facts on H2SO3 + CaCl2: What, How To Balance & FAQs

Chemical reactions result in the conversion of key reactant species to economical and stable products for industrial growth. Let us know about the chemical reactivity of H2SO3 and CaCl2.

H2SO3 is a reducing agent formed as an intermediate component during acid rain formation from SO2. CaCl2 a hygroscopic deliquescent inorganic compound is used for the de-icing process. The reaction between H2SO3 and CaCl2 forms calcium sulfite.

The reactivity of H2SO3 and CaCl2 was assessed for its flue gas desulphurization conditions. Moreover, the following chemical characteristics of the reacting species can be discussed.

What is the product of H2SO3 and CaCl2?

H2SO3 and CaCl2 react to form calcium sulfite and hydrogen chloride.

H2SO3 + CaCl2 = CaSO3 + HCl

What type of reaction is H2SO3 + CaCl2?

H2SO3 + CaCl2 is a substitution reaction where sulfite and chloride anion interchange their respective cation species to form new compounds.

How to balance H2SO3 + CaCl2?

The following algebraic method can be used to balance the reaction

H2SO3 + CaCl2 = CaSO3 + HCl,

  • Each reactant and product in the equation is labelled with a variable (A, B, C, and D) to represent unknown coefficients.
  • A H2SO3 + B CaCl2 = C CaSO3 + D HCl
  • Now, an appropriate quantity thought of as the coefficient of reactants and products, is used to solve the equation.
  • H = 2A = 2D, S = A = C, O = 3A = 3C, Ca = B = C, Cl = 2B = D
  • The Gaussian elimination method is used to determine all the variables and coefficients, and the results are
  • A = 1, B = 1, C = 1, and D = 2
  • Accordingly, the overall balanced equation is,
  • H2SO3 + CaCl2 = CaSO3 + 2 HCl

H2SO3 + CaCl2 titration

The titration of H2SO3 + CaCl2 is not possible as H2SO3 normally exists as a gas and CaCl2 is a salt and there is no base present in this system.  

H2SO3 + CaCl2 net ionic equation

The net ionic equation of Ca + H2SO4 is

SO3-2 (aq) + Ca+2 (aq) = CaSO3 (s)

  • Write the balanced chemical equation and represent the physical states of reactants and products accordingly
  • H2SO3 (aq) + CaCl2 (aq) = CaSO3 (s) + 2 HCl (aq)
  • Now, strong acids, bases, and salts dissociate into ions whereas pure solid substances and molecules do not dissociate
  • Thus, the net ionic equation is
  • SO3-2 (aq) + Ca+2 (aq) = CaSO3 (s)

H2SO3 + CaCl2 conjugate pairs

CaCl2 + H2SO4 reaction has the following conjugate pairs,

  • H2SO3 forms HSO3 as conjugate base.
  • CaCl2 does not form conjugate pair because it does not contain any proton.

H2SO3 and CaCl2 intermolecular forces

CaCl2 + H2SO4 reaction has the following intermolecular forces,

  • H2SO3 molecules are bonded together via strong covalent bonds.
  • CaCl2 interacts using ion-dipole forces.

H2SO3 + CaCl2 reaction enthalpy

H2SO3 + CaCl2 reaction enthalpy is -1206.9 kJ/mol.

Is H2SO3 + CaCl2 a buffer solution?

H2SO3 + CaCl2 is not a buffer solution because H2SO3 is a strong acid that cannot be a part of the buffer.

Is H2SO3 + CaCl2 a complete reaction?

H2SO3 + CaCl2 is a complete reaction as calcium sulfite and hydrogen chloride are formed as stable products.

Is H2SO3 + CaCl2 an exothermic or endothermic reaction?

H2SO3 + CaCl2 is an exothermic reaction due to the liberation of heat with the addition of strong sulfurous acid.

Is H2SO3 + CaCl2 a redox reaction?

H2SO3 + CaCl2 is not a redox reaction because the oxidation states of elements do not change during the reaction.

Is H2SO3 + CaCl2 a precipitation reaction?

H2SO3 + CaCl2 is a precipitation reaction because solid calcium sulfite precipitates at the end of the reaction.

Is H2SO3 + CaCl2 reversible or irreversible reaction?

H2SO3 + CaCl2 is an irreversible reaction because the formed products (CaSO3 and HCl) cannot convert back into the original reactants.

Is H2SO3 + CaCl2 displacement reaction?

H2SO3 + CaCl2 is a double displacement reaction because both the anion component of the reactants is displaced with the respective cationic part.


The reactivity of H2SO3 + CaCl2 forms calcium sulfite which is the product of flue gas desulphurization. It is widely used as preserving canned edibles, and wines acting as an oxygen scavenger. Another application involves the production of wood pulp by dissolving lignin from the woods.