Hypoiodous Acid: Synthesis, Properties & Uses

Hypoiodous acid is an inorganic compound and an iodine oxoacid. It is a greenish-yellow solution with the chemical formula HIO. Hypoiodous acid is formed when an aqueous solution of iodine is treated with silver salts. 

• It is the conjugate acid of a hypoiodite. 
• The solution is prepared by the removal of the proton, which results in the formation of hypoiodite. 
• Hypoiodite is present in the form of a monovalent ion, which is an inorganic compound. 
• It is obtained through dehydration (which is the process of removal of a proton) of the acidic compound HOI. 
• Hypoiodous acid, present in the form of iodine oxide, is a monovalent inorganic an-ion and also an iodine oxoanion. 
• The solution is a volatile species of iodine.
• It is neither elemental nor organic. 

Key Terms: Hypoiodous Acid, Properties of Hypoiodous Acid, Structure of Hypoiodous acid, Synthesis of Hypoiodous Acid, Uses of Hypoiodous Acid, Iodine Oxide, Iodine, Chemical Formula, Oxoacid

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What is Hypoiodous Acid?

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Hypoiodous Acid is a chemical solution which is greenish-yellow in colour. The chemical formula of Hypoiodous Acid is HIO. When iodine acts as a catalyst, it reacts with hydroxyoxidanium to form Hypoiodous Acid. 

• Hypoiodous Acid can also be formed along with iodide ions by the dissolving process. 
• In this, iodine is dissolved in dilute alkali or acted upon by the mercuric oxide upon water or iodine. 
• Hypoiodous Acid can be found in steam or air atmospheres. 
• It is also known as Oxdoiodine.
• The acid is formed by a disproportionation reaction, which is as follows:

5 HIO → HIO₃ + 2 I₂ + 2 H₂O

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Hypoiodous Acid Structure

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The bonding of hydroxide and iodine ions forms the structure of Hypoiodous Acid. It is formed by the unequal sharing of electrons, which takes place inside the atoms in the molecule.

• Iodine and oxygen are electronegative elements which result in the attraction of electrons.
• When the charge is separated from the atoms, then, it results in the bending of the structure of Hypoiodous Acid.
• The hybridisation of the iodine compound is sp³.
• The molecules are bonded of covalent bonds with oxygen atoms bearing negative charge.​

Structure of Hypoiodous Acid 

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Properties of Hypoiodous Acid

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The properties of Hypoiodous acid is divided into physical and chemical categories which are as follows:

Physical Properties of Hypoiodous Acid

The physical properies of Hypoiodous acid are as follows:

• Hypoiodous Acid appears in the form of a greenish-yellow solution.
• It doesn’t have any particular odor.
• The acid is dissolved very quickly in water or aqueous solutions.
• Conjugate base of Hypoiodous Acid is known as hypoiodite.
• The molecular weight or molecular mass is 143.912 g/mol.
• The number of heavy atoms is 2 more than the number of isotopes atoms is 0.
• The complexity of Hypoiodous Acid is 2.

The physical properies of Hypoiodous acid is tabulated as follows:

Chemical Properties of Hypoiodous Acid

The chemical properties of Hypoiodous Acid are as follows:

• The exact mass of Hypoiodous Acid is 143.90721 g/mol. 
• It is a similar monoisotopic mass.
• The topological surface area of this acid has a property value of 20.2 A².
• It has one hydrogen bond donor, which is identical to the number of hydrogen bond acceptors.
• The number of covalently-bonded units of Hypoiodous Acid is 1.
• It is a powerful oxidizing agent.
• The density of the substance is 3.207 grams per cubic centimetre. 

The chemical properies of Hypoiodous acid is tabulated as follows:

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Synthesis of Hypoiodous Acid

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HIO Acid is highly unstable & it’s weak in comparison to other acids. It can be easily obtained via the treatment of mercury oxide with iodine. HIO can also form unstable salts in a solution when iodine reacts with alkali.

• The synthesis of Hypoiodous Acid occurs when iodine reacts with a cold & dilute solution of sodium hydroxide.
• After that, it results in sodium hypoiodite & then hydrolyses to form the chemical compound Hypoiodous Acid.

Methods of Synthesis of Hypoiodous Acid 

The various methods are as follows:

• The following equation will make you understand the occurrence of HOI.

2NaOH + I₂ -> NaIO + NaI + H₂ ………(1)

So, the above equation shows that the interactions take place between sodium hydroxide & iodine respectively. The reaction results in the formation of sodium hypoiodite, sodium iodide & also water.

• Here is the second equation that depicts the breakdown of the components compiled.

NaIO + H₂O -> NaOH + HIO …….(2)

With the above equation, it can be said that the interaction between sodium hypoiodite & iodine forms sodium hydroxide & Hypoiodous Acid.

• The third equation depicts the formation of iodine & Hypoiodous Acid.

I₂ + H ₂O -> HIO + I ^- + H ⁺

So with the equation, it is clear that iodine gets dissolved in water and it generated HIO and iodide. The interactions between HIO atoms or molecules result in iodous acid iodide.

• These are some equations for the same :

2 HIO -> HIO ₂ + I + H ⁺

HIO₂ HIO -> IO^{- 3} + I ^- + 2 H ⁺.

2 HIO ₂ -> IO ^{- 3} + HIO + H ⁺

• Hence, the Acidic Component also get dissolves in water to form hypoiodite. The equation is as follows-

HIO -> IO ^- + H ⁺

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Applications of Hypoiodous Acid

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Various applications of Hypoiodous Acid are as follows:

• Hypoiodous Acid is used in the treatment of drinking water.
• It is used in rocket fuels and also used in insulation in industrial sectors.
• The acid is used in the prevention, reduction & control of pests in the agricultural sectors.
• The maximum use of the complex protects the crops & plants from harmful pets that destroy the plants.
• Hypoiodous Acid is also used in the field of atmospheric samplers.
• It helps in studying & exaggerating the abnormal increasing rate of the organic fractions.
• The solution is also applied to remove the chloramines from water in the swimming pools to reduce eye irritations.
• It is also used as a vital agent in removing microbial fungal growth.

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Things to Remember

• Hypoiodous acid is used in several fields as it is one of the most useful chemical compounds. 
• It is different from other acids as it is weaker than the other ones.
• The chemical compound HIO forms iodine's oxyacid when iodine gets completely dissolved in water.
• Hypoiodous Acid exists as a conjugate acid that appears from a hypoiodite. 
• The key compounds of iodine are used for sanitization purposes.

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