# 15 Facts on H2SO3 +KClO3: What, How To Balance & FAQs

Potassium chlorate (KClO3) is a highly reactive chlorate salt, and H2SO3 (sulfurous acid) is an inorganic sulphur oxo acid. Let us examine their reaction in detail.

KClO3 is a white monoclinic crystal with a saline taste. It is a chemical oxygen generator in laboratories. As a powerful oxidizing agent, it is primarily used in fireworks. H2SO3 is a colorless inorganic acid, soluble in water. As a reducing agent, it is used as a bleaching agent.

In this article, let us discuss important features of the reaction H2SO3 + KClO3, such as the product formed, the type of reaction, enthalpy change etc.

## What is the product of H2SO3 and KClO3?

Potassium chloride (KCl) and sulphuric acid (H2SO4) are the products formed when sulphurous acid reacts with potassium chlorate.

3H2SO3 + KClO3 ——-> KCl + 3H2SO4

## What type of reaction is H2SO3 + KClO3?

H2SO3 + KClO3 is an oxidation-reduction (redox) type of reaction.

## How to balance H2SO3 + KClO3?

H2SO3 + KClO3 is balanced using the following steps

KClO3 + 3H2SO3  = KCl + 3H2SO4

• To denote the unknown coefficients, assign an alphabet to each compound of the reaction.
•  a KClO3 + b H2SO3  = c KCl + d H2SO4
• Create an equation by equating the coefficients of same type, for each element, involved in the reaction.
• H → 2b=2d, S → b=c, Cl → a=c, K → a=c, O → 3a+3b=4d
• Determine the values of each assigned coefficient by using the Gaussian elimination method.
• The value of coefficients obtained after simplification
• a=1, b=3, c=1, d=3.
• Therefore, the balanced equation after substituting the values of all the coefficients is –
• KClO3 + 3H2SO3  =  KCl + 3H2SO4

## H2SO3 + KClO3titration

A redox titration between H2SO3 and KClO3 is carried out to determine the amount of potassium and chlorine.

#### Apparatus

Burette, burette holder, pipette, wash bottle, conical flask,  volumetric flask, dropper and beakers.

#### Indicator

Phenolphthalein is used as the indicator as the titration is done in an acidic medium.

#### Procedure

• The burette is filled with standardized H2SO3.
• The KClO3 solution is pipetted out and transferred into the conical flask.
• Add a few drops of phenolphthalein indicator.
• H2SO3 is added drop by drop into the conical flask, and the flask is swirled constantly.
• The appearance of pale pink color marks the equivalence point of the titration.
• Note the burette reading and repeat the procedure for 3 concordant readings.
• The quantity of potassium and chlorine is estimated by using the formula, V1S= V2S2.

## H2SO3 + KClO3net ionic equation

The net ionic equation between H2SO3 + KClO3 is:

3H2SO3 (aq)+ ClO3 (aq) = Cl (aq) + 2H+ (aq) + SO42- (aq)

To elucidate the net ionic equation, the following steps are followed –

• The balanced equation along with its physical state is written first.
• 3H2SO3 (aq) + KClO3 (aq) =  KCl(aq)  + H2SO4 (aq)
• The electrolytes, which are strong, are split into their respective ions. H2SO3 is a weak electrolyte, while KClO3, KCl, and H2SO4 are strong electrolytes in an aqueous solution. The equation now becomes,
• 3H2SO3(aq) + K+(aq) + ClO3 (aq) =  K+(aq) + Cl(aq) + 2H+(aq) + SO42-(aq)
• The spectator ions (K+) are cancelled on both sides of the equation to get the net ionic equation.
• 3H2SO3 (aq)+ ClO3 (aq) = Cl (aq) + 2H+ (aq) + SO42- (aq)

## H2SO3 + KClO3conjugate pairs

• Conjugate base of H2SO3 as HSO3
• KClO3 is a neutral salt, so it has no conjugate pair.

## H2SO3 + KClO3reaction enthalpy

H2SO3 + KClO3 reaction enthalpy is -205.3 KJ/mol.

• Enthalpy values of reactants and products involved in the reaction are listed below –
• The enthalpy of the reaction is obtained by using the formula: enthalpy of products – enthalpy of reactants.
• ∆Hf°(reaction) = ∆Hf°(products) – ∆Hf°(reactants)
• = -1252 – (-1046.7) KJ/mol
• = -205.3 KJ/mol

## Is H2SO3 + KClO3 a buffer solution?

H2SO3 + KClO3 does not form a buffer solution, as KClO3 is a neutral salt formed by the neutralization reaction of a strong acid and a strong base.

## Is H2SO3 + KClO3 a complete reaction?

H2SO3 + KClO3  is a complete reaction since the products are completely formed at equilibrium.

## Is H2SO3 + KClO3 an exothermic reaction?

H2SO3 + KClO3 is an exothermic reaction following thermodynamics first law. Moreover, the reaction enthalpy is found to be negative.

## Is H2SO3 + KClO3 a redox reaction?

H2SO3 + KClO3 is a redox reaction where,

• Sulphur is oxidized from +4 to +6 oxidation state.
• Chlorine is reduced from +5 to -1 oxidation state.

## Is H2SO3 + KClO3 a precipitation reaction?

H2SO3 + KClO3 is not a precipitation reaction as the products formed are completely soluble in the reaction mixture.

## Is H2SO3 + KClO3 an irreversible reaction?

H2SO3KClO3 is an irreversible reaction as the products formed react with each other to form chlorine gas, so reverse reaction is not favoured.

## Is H2SO3 + KClO3 a displacement reaction?

H2SO3 + KClO3  is not a displacement reaction, as there is no swapping or displacement of ions during product formation.

#### Conclusion

The reaction of KClO3 with H2SO3 is a redox and exothermic reaction. KClO3 should be handled carefully as it is combustible in nature. H2SO3 and KClO3 are widely used as reducing and oxidizing agents, respectively.