15 Facts on HI + KOH: What, How to Balance & FAQs

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Potassium hydroxide (KOH) is also known as “caustic potash” and is an inorganic basic compound. Hydrogen iodide(HI) is acidic in nature. Let us study the reaction of HI + KOH.

HI is a diatomic molecule containing hydrogen and iodide, is also known as hydroiodic acid in aqueous state. As iodine is larger than hydrogen, the overlapping of the electron cloud is improper because of which bond energy between both is very little. KOH is hygroscopic and its dissolution in water is exothermic.

The following editorial will study facts related to HI + KOH reaction.

What is the product of HI and KOH?

Potassium iodide (KI) and water (H2O) are the products of the reaction between HI+KOH.

HI + KOH→KI + H2O

What type of reaction is HI + KOH?

The reaction HI + KOH is a neutralization reaction and exothermic as HI is acid and KOH is the base. Therefore, on reacting, they form a salt, i.e., KI.

How to balance HI + KOH

To balance the reaction HI + KOH following steps are used.

  • The first step is to observe whether the number of atoms on the product side and the reactant side is equal.
  • In the next step, if the number of atoms on both the reactant and product sides is unequal, then we have to balance that.
  • Here reaction is HI + KOH → KI + H2O
  • In reactant side- two hydrogen atoms, one potassium atom, one iodine atom and one oxygen atom are there, whereas two hydrogen atoms, one oxygen atom, one potassium atom and one iodine atom are present in the product side.
  • This counting indicates equal atoms on the reactant and product sides, so it’s already balanced.

HI + KOH titration

HI+ KOH titration follows the following procedure.

Apparatus used

Burette, Burette stand, Pipette, Conical flask, Volumetric flask.

Indicator

Phenolphthalein indicator used in titration shows pink color in basic solution and colorless in acidic solution.

Procedure

  • All apparatus is washed and dried before titration. There should not be any water content or moisture inside any apparatus, which can vary titration point.
  • KOH is a strong base taken in the conical flask. It is called Analyte.
  • In the burette, HI is taken, which is called titrant.
  • Before titration in a conical flask containing KOH, a few drops of phenolphthalein indicator are added.
  • The indicator causes a change in the color of the KOH solution, which confirms the equivalence point has been reached.
  • When we add acid from the burette to the conical flask containing KOH solution, a color change will appear, which indicates acid has reacted with strong base KOH.
  • Now titrant in the burette is added slowly, drop by drop, to the conical flask.
  • Shake it properly so that HI will react properly with KOH.
  • After some time, the endpoint is reached, which shows the change in the color of the conical flask solution; this indicates the base has been fully titrated.
  • The amount of KOH can be calculated from the amount of HI consumed by KOH.
  • V KOH * S KOH = V HI * S HI
  • V indicates volume and S concentration.
  • This way, we can determine the amount of KOH required to neutralize HI.

HI + KOH net ionic equation

The net ionic equation of HI + KOH is given below.

H+(aq) + I–(aq) + K+(aq) + OH–(aq) = K+(aq) + I–(aq) + H2O(l)

  • HI is a strong acid,it dissociates completely in an aqueous solution.
  • I– anion is common both sides, so it gets canceled out.

HI + KOH conjugate pairs

The reaction HI + KOH has the following conjugate pairs-

  • I – is the conjugate base of the strong acid HI.
  • K+ is the conjugate acid of the strong base KOH.

HI and KOH intermolecular forces.

HI + KOH has the following intermolecular forces-

  • In HI, a strong dipole-dipole interaction between the ions exists.
  • In case of KOH, London dispersion forces, dipole-dipole forces and hydrogen bonding are present.

HI and KOH reaction enthalpy.

HI + KOH reaction enthalpy is -113.81 KJ/mol.

The formula for enthalpy calculation= Enthalpy of Product-Enthalpy of reactant.

MoleculeEnthalpy (KJ/mol)
HI-26.48
KOH482.37
KI-327.9
H2O-241.8
Reaction Enthalpy-113.8
Enthalpy of reaction

Is HI + KOH a buffer solution?

The reaction of HI + KOH will not give a buffer solution. It is because of the strong acid, i.e., HI and KOH are strong bases as they get ionize completely.

Is HI + KOH a complete reaction?

HI + KOH is a complete reaction because the potassium iodide and water are formed as product, and no more steps are left to be completed.

Is HI + KOH an exothermic or endothermic reaction?

HI + KOH is an exothermic reaction because of the negative enthalpy value (-113.8 KJ/mol) obtained from the chemical reaction.

Is HI + KOH a redox reaction?

HI + KOH is a redox reaction where, HI acts as a reducing agent and KOH as an oxidizing agent.

Is HI + KOH a precipitation reaction?

HI + KOH is a precipitation reaction because crystals of potassium iodide are obtained, which are insoluble in water.

Is HI + KOH reversible or irreversible reaction?

The reaction HI + KOH is irreversible since complete products are obtained that do not revert to the reactants.

Is HI + KOH displacement reaction?

HI + KOH is a double displacement reaction because it is a neutralization reaction which indicates that it is an example of double displacement reactions in which KI is produced as a salt along with water.

Conclusion

The reaction of hydroiodic acid with potassium hydroxide results in the formation of potassium iodide as a salt, along with water-insoluble in water. Potassium hydroxide act as nucleophile and hydrogen iodide as reducing agent in organic chemistry.