13 Facts on HI + KMnO4: What, How To Balance & FAQs

In a chemical reaction, breaking of old bonds and formation of new bonds take place. Let us explore the chemical reactivity of HI and KMnO₄.

KMnO₄ is the chemical formula of potassium permanganate, which is most commonly used as an oxidising agent in volumetric analysis. KMnO₄ is a purplish colored crystalline solid. It is used in a large number of titrations. HI is the common reducing agent for many organic synthesis. HI is a gas under standard conditions

In this article, we will learn about a few properties on the reaction between HI and KMnO₄ like the type of reaction, the product formed, buffer solution, conjugate pairs, type of intermolecular forces etc.

What type of reaction is HI + KMnO₄ ?

The reaction between HI and KMno₄ is an oxidation-reduction (redox) reaction:
2MnO₄⁻ + 4H₂O(ℓ) + 6I⁻(aq) → 2MnO₂(s) + 8OH⁻(aq) + 3I₂(aq)

How to balance HI + KMnO₄?

The HI and KMnO₄ reaction can be balanced by following these steps:

• Separate the half-reactions:
• 2 Mn⁺⁷+ 10 e^– → 2 Mn⁺² (reduction) and 10 I^-1 + 10 e^– → 10 I⁺⁰(oxidation)
• Balance all elements other than O and H.
• Add H₂O to balance oxygen.
• Balance hydrogen with protons.
• Balance the charge with e-.
• Scale the reactions so that they have an equal amount of electrons.
• Thus, the balanced chemical equation of the reaction between HI and KMno₄ is:
  2KMnO₄ + 16HI → 2 MnI₂ + 2 KI + 8 H₂O + 5I₂

HI + KMnO₄ titration?

The HI + KMnO₄ system is not performed as titration because hydrogen iodide (HI) is a gas in standard conditions whereas one requires liquid or aqueous solutions for estimation using titration.

HI + KMnO₄ net ionic equation ?

• The net ionic equation of HI + KMnO₄ is:
  2MnO₄⁻ + 4H₂O(ℓ) + 6I⁻(aq) → 2MnO₂(s) + 8OH⁻(aq) + 3I₂(aq)

The net ionic equation is obtained using the following steps –

• Write the balanced chemical equation and designate the physical states of reactants and products accordingly,
  KMnO₄+ 16HI → 2 MnI₂ + 2 KI + 8 H₂O + 5I₂
• Strong acids, bases, and salts dissociate into ions whereas pure solid substances and molecules do not dissociate.
• Thus, the net ionic equation is obtained-
  2MnO₄⁻ + 4H₂O(ℓ) + 6I⁻(aq) → 2MnO₂(s) + 8OH⁻(aq) + 3I₂(aq)

HI + KMnO₄ conjugate pairs?

The conjugate pairs of the reaction HI + KMnO₄ is:

The conjugate pair of HI is I^–.There does not exist any conjugate pair for KMnO₄.

HI and KMnO₄ intermolecular forces ?

Dispersion forces and Dipole-dipole forces are the Intermolecular forces present between KMnO₄ and HI compounds.

HI + KMnO₄ reaction enthalpy ?

• HI + KMnO₄ exhibits a negative reaction enthalpy because of the formation of an ionic compound.
• HI + KMnO₄ is an exothermic reaction due to the evolution of heat.
• Thus, heat is liberated to show a negative enthalpy value.

Is HI + KMnO₄ a buffer solution ?

HI + KMnO₄ does not form a buffer solution due to the fact that the buffer is made by weak acid and salt of its conjugate base whereas HI is not a weak acid and is not a salt of the conjugate base of HI.

Is HI + KMnO₄ a complete reaction ?

HI + KMnO₄ is a complete reaction because the stable products namely MnI₂, water, and I₂ gas are produced.

Is HI + KMnO₄ an exothermic or endothermic reaction ?

HI + KMnO₄ is an exothermic reaction because heat is liberated due to the formation of an ionic compound i.e., MnI₂ which determines a negative enthalpy value.

Is HI + KMnO₄ a redox reaction ?

HI + KMnO₄ is a redox reaction because iodine and oxygen are oxidized and manganese is reduced in the ongoing reaction.

Is HI + KMnO₄ a precipitation reaction ?

HI + KMnO₄ is not a precipitation reaction as MnI₂ produced in the reaction is highly soluble in water. Thus no precipitate is formed when the reaction ends.

Is HI + KMnO₄ reversible or irreversible reaction ?

HI + KMnO₄ is an irreversible reaction because the products formed in the reaction do not change back into the original reactants when the conditions are kept the same.

Is HI + KMnO₄ displacement reaction ?

HI + KMnO₄ is a displacement reaction because the anion from the acid replaces the oxygen.

Conclusion –

KMnO₄ is usually stored in tightly closed containers. KMnO₄ is also used in tanning leathers and printing fabrics. This compound can even be used as a bleaching agent and as a pesticide.