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
No. of moles of each element on both sides of reaction

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.

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