N Facts on H2SO3 + K2Cr2O7: What, How To Balance & FAQs

H2SO3 + K2Cr2O7 is a reaction between an acid and an inorganic chemical reagent which is an unusual reaction combination. Let us inspect various facts related to it in this article.

H2SO3 + K2Cr2O7 reaction involves reactants sulfurous acid and potassium dichromate. Sulfurous acid is an intermediate acid that does not exist in the liquid phase and is not stable unlike its counterpart H2SO4. Potassium dichromate is an oxidizing reagent and a popular laboratory chemical.

H2SO3 + K2Cr2O7 reaction leads to the product Cr2(SO4)3, potassium sulfite, and water. Let us understand various aspects attached to it like the reaction type, product formation, titration, forces, etc.

What is the product of H2SO3 and K2CR2O7?

H2SO3 + K2Cr2O7 reaction leads to the formation of 3 products which are chromium sulfate (Cr2(SO4)3), potassium sulfite (K2SO3), and water (H2O). Here chromium sulfate is the main product and the rest of them are the by-products of the reaction.

What type of reaction is H2SO3 + K2CR2O7?

H2SO3 + K2Cr2O7 is a combination reaction and a redox reaction where K2Cr2O7 is an oxidizing agent.

How to balance H2SO3 + K2CR2O7?

H2SO3 + K2Cr2O7 reaction can be balanced using the algebraic method:

  • Write the equation in its unbalanced form where atoms are not yet balanced.
  • Draw a table mentioning the no. of individual atoms in both reactants and product side of the reaction.
  • Balance both the sides of the reactants and the products by the hit and trial method.
  • Check the stoichiometry and rewrite the balanced equation.

H2SO3 + K2CR2O7 titration

H2SO3 + K2Cr2O7 titration is not possible because H2SO3 is a weak acid and K2Cr2O7 is a potassium salt of dichromate, a strong chemical reagent used as an oxidizing agent. Hence the compatibility of these 2 reactants made them unfit for the process of titration. 

H2SO3 + K2CR2O7 net ionic equation

The H2SO3 + K2Cr2O7 net ionic equation cannot be calculated due to the absence of complete information about its solubility quotient which decides the dissociation of the individual molecules.

H2SO3 + K2CR2O7 conjugate pairs

Conjugate pairs in a reaction involve the acceptance and donation of the proton or hydrogen ion where acid and base have their conjugate base and acid respectively.

  • In H2SO3 + K2Cr2O7 reaction the conjugate base for H2SO3 is HSO3- which is a bisulfate anion.
  • The conjugate pair for K2Cr2O7 does not exist because of the absence of protons.
  • The conjugate base for H2O is the OH- ion.

H2SO3 and K2CR2O7 intermolecular forces

H2SO3 + K2Cr2O7 exhibit the following intermolecular forces:

  • H2SO3 shows covalent bonding and van der Waal forces both of which are weak intermolecular forces because of sharing of electrons.
  • K2Cr2O7 on the other hand is the complete opposite of its reactant counterpart and exhibits strong ionic forces where 2 ionic bonds are formed between K+ and Cr2O72-.

H2SO3 + K2CR2O7 reaction enthalpy

H2SO3 + K2Cr2O7 reaction enthalpy is near to that of the reaction between H2SO4 and K2Cr2O7 which is -85.9 KJ/mol. Much information is not available about it due to stability concerns attached to H2SO3. H2SO3 is not a complete and stable acid and exists in gaseous form for maximum times.

Is H2SO3 + K2CR2O7 a buffer solution?

H2So3 + K2Cr2O7 cannot form a buffer solution because the reactant K2Cr2O7 is not an acid or base. Instead, it is a salt. A buffer solution between a weak acid and an ionic salt is not possible.

Is H2SO3 + K2CR2O7 a complete reaction?

H2SO3 + k2Cr2O7 is a complete reaction where the reaction is considered completed after the formation of products in their desired stoichiometric quantities. It also means that all the reactants are used.

Is H2SO3 + K2CR2O7 an exothermic or endothermic reaction?

H2SO3 + K2Cr2O7 is an exothermic reaction due to its large entropy and the ability to release heat during the reaction.

Is H2SO3 + K2CR2O7 a redox reaction?

H2SO3 + k2Cr2O7 is a redox reaction because the oxidation number of the reactant is different from that of the product which implies that there is addition and removal of electrons. Here K2Cr2O7 is an oxidizing agent and H2SO3 is a reducing agent.

Is H2SO3 + K2CR2O7 a precipitation reaction?

H2SO3 + K2Cr2O7 is not a precipitation reaction because the products formed are of aqueous nature which implies that there is no sedimentation or insoluble product in the reaction mixture.

Is H2SO3 + K2CR2O7 a reversible or irreversible reaction?

H2SO3 + K2Cr2O7 is an irreversible reaction because the products formed cannot be interconverted into reactants and exists in fixed quantities after the completion of the reaction.

Is H2SO3 + K2CR2O7 displacement reaction?

H2SO3 + K2Cr2O7 is not a displacement reaction as no exchange of anions and cations are observed between the reactants and the products. Instead, it is a redox reaction due to the properties of its reactants.


In a nutshell, H2SO3 + K2Cr2O7 is an anomalous and rare reaction where the reactants are weak acid and salt. Their properties, forces, and structural formation are opposite to each other.