11 Facts on HCl + FeS2: What, How To Balance & FAQs

HCl + FeS2 is another inorganic chemical reaction that produces 3 products. Let us inspect various facts related to it in this article.

The reactants used in the reaction of HCl + FeS2 are hydrochloric acid and iron disulfide. HCl is a very common and corrosive mineral acid that can react with metals. FeS2 on the other hand is a yellow color metal that is responsible for SO2 production.

FeS2 + HCl undergoes a reaction that produces FeCl2 as the main product and S and H2S as the by-products. Let us inspect various characteristics related to this reaction like titration, balancing, forces, etc.

What is the product of HCl and FeS2?

HCl + FeS2 reaction produces FeCl2 as the main product and H2S and S as the by-product. Here FeCl2 is observed in pale green color and the presence of H2S can be judged through its rotten egg smell.

FeS2 + 2HCl = FeCl2 + H2S + S

iron chloride
Product of HCl + FeS2

What type of reaction is HCl + FeS2?

HCl + FeS2 exhibits a redox reaction also called disproportionation or dismutation reaction.

How to balance HCl + FeS2?

HCl + FeS2 reaction can be balanced using the hit and trial method following certain steps:

  • Write the whole equation mentioning the reactant and products.
  • Mention the number of atoms of individual elements on both the reactant and product side in tabular form.
  • Balance the elements on both the reactant and product side by the addition of atoms.
  • Write the balanced equation again according to stoichiometric quantities.

HCl + FeS2 = FeCl2 + H2S + S

Elements No. of atoms (Reactants) No. of atoms (Products)
Hydrogen (H) 1 x 2 = 2 2
Chlorine (Cl) 1 x 2 = 2 2
Iron (Fe) 1 1
Sulfur (S) 2 2
HCl + FeS2 balancing equation table

2HCl + FeS2 = FeCl2 + H2S + S

HCl + FeS2 net ionic equation

FeS2 + HCl net ionic equation cannot be written as it is an exception due to less information about the solubility state of the reactants and products. For writing net ionic equations, the compound needs to be in an aqueous form which ensures the dissociation of compounds into ions.

HCl + FeS2 conjugate pairs

HCl + FeS2 does not exhibit conjugation as it is observed in acid-base pairs where there is an exchange of H+ ions and the formation of conjugate acids and bases. But HCl + FeS2 undergoes disproportionation which makes conjugation impossible.

HCl and FeS2 intermolecular forces

HCl + FeS2 reaction can have the following intermolecular forces,

  • HCl is a strong mineral acid that exhibits the London dispersion forces and the dipole-dipole interaction due to major electronegativity differences between H+ and Cl ions.
  • FeS2 is an ionic crystal structure due to which it shows ionic properties and strong electrovalent properties.

Is HCl + FeS2 a complete reaction?

HCl + FeS2 is a complete reaction because the equilibrium of the reaction is achieved and there is no reversal. Also, the concentration of reactants and products is not changing continuously. This also implies that the concentration of reactants has become zero after completion.

Is HCl + FeS2 an exothermic or endothermic reaction?

HCl + FeS2 is an exothermic reaction as the reaction between an acid and a metal compound produces heat in the product. In HCl + FeS2 reaction H2S and S are produced which generate heat and energy.

Is HCl + FeS2 a redox reaction?

HCl + FeS2 is a redox reaction where one of the reactants is reducing and another one is simultaneously oxidizing. But it exhibits an anomalous situation where FeS2 is both oxidizing and reducing agent, unlike many redox reactions.

Is HCl + FeS2 a precipitation reaction?

HCl + FeS2 is not a precipitation reaction as there are no insoluble products formed which settle at the bottom of the reaction mixture and then recrystallize. The product FeCl2 formed is aqueous and is separated by chemical washings.

Is HCl + FeS2 a reversible or irreversible reaction?

HCl + FeS2 is an irreversible reaction as the equilibrium is in a forward reaction and the phases of the products cannot be reversed. Here FeCl2 is in an aqueous phase and H2S formed solidifies thereby restricting the backward reaction.

Is HCl + FeS2 displacement reaction?

HCl + FeS2 is not a displacement reaction as there are no exchanges between the cations and anions of the reactants which form the products. Instead, it is a disproportionation reaction.

Conclusion

Concluding the article then HCl + FeS2 is a redox reaction with an exception where only FeS2 is both an oxidation and reducing agent. It is like any other inorganic reaction between an acid and a metal compound which could lead to corrosion of the metal involved and produce heat in the process.