Iodic Acid (HIO3): Structure, Properties, Risks And Uses

The iodic acid is an inorganic compound of formula HIO 3 . It is an oxacid acid of iodine, which has an oxidation state of +5 in this molecule. This compound is a very strong acid and is often used to standardize solutions of weak and strong bases to prepare them for titrations.

It is formed by oxidizing diatomic iodine with nitric acid, chlorine, hydrogen peroxide or hydrochloric acid as shown in the following reaction: I 2 + 6H 2 O + 5Cl 2 ⇌ 2HIO 3 + 10HCl.

Figure 1: Structure of iodic acid.

In each reaction, diatomic iodine loses electrons and forms a complex with hydrogen and oxygen. Due to its ionic and soluble properties, ionic acid is also a very strong acid.

Article index

  • one

    Physical and chemical properties of iodic acid

  • two

    Reactivity and hazards

  • 3

    Uses and health benefits

  • 4


Physical and chemical properties of iodic acid

Iodic acid is a white solid at room temperature (Royal Society of Chemistry, 2015). 

appearance of iodic acid

Figure 2: appearance of iodic acid.

Iodic acid has a molecular weight of 175.91 g / mol and has a density of 4.62 g / ml. It is very soluble in water, being able to dissolve 269 grams of acid per 100 ml. Its melting point is 110 degrees Celsius, where it begins to decompose dehydrating to iodine pentoxide.

On subsequent heating of the compound to a higher temperature, it decomposes to give a mixture of iodine, oxygen, and lower iodine oxides (National Center for Biotechnology Information, SF).

It is a relatively strong acid with an acidity of 0.75. The iodine or iodide ion is the product of this compound when it is oxidized. At very low pH and high chloride ion concentration it reduces to iodine trichloride which is a yellow compound in solution.

Reactivity and hazards

Iodic acid is a stable compound under ordinary conditions. Being a strong acid, it is extremely dangerous in case of contact with the skin (corrosive and irritant), contact with the eyes (irritant) and in case of ingestion. In addition, it is very dangerous also in case of inhalation (IODIC ACID, SF).

The amount of tissue damage depends on the length of the contact. Contact with the eyes can result in corneal damage or blindness. Contact with the skin can cause inflammation and blisters. Inhalation of dust will produce irritation of the gastrointestinal or respiratory tract, characterized by burning, sneezing and coughing.

Severe overexposure can cause lung damage, suffocation, loss of consciousness, or death. Prolonged exposure can cause skin burns and ulcerations. Inhalation overexposure may cause respiratory irritation.

Inflammation of the eye is characterized by redness, watering, and itching. Inflammation of the skin is characterized by itching, peeling, redness, or occasionally blistering.

The substance is toxic to the kidneys, lungs and mucous membranes.

Repeated or prolonged exposure to the substance can cause damage to these organs and irritation to the eyes. Periodic exposure to the skin can cause local destruction of the skin, or dermatitis.

Repeated inhalation of dust can produce varying degrees of respiratory irritation or lung damage. Prolonged inhalation of dust can cause chronic respiratory irritation.

In case of contact with the eyes, check if you are wearing contact lenses and remove them immediately. The eyes should be rinsed with running water for at least 15 minutes, keeping the eyelids open, being able to use cold water. Eye ointment should not be used.

If the chemical comes into contact with clothing, remove it as quickly as possible, protecting your own hands and body. Place the victim under a safety shower.

If the chemical accumulates on the exposed skin of the victim, such as hands, the contaminated skin is gently and carefully washed with running water and non-abrasive soap. If irritation persists, seek medical attention and wash contaminated clothing before reuse.

If the skin contact is severe, it should be washed with a disinfectant soap and cover the contaminated skin with an antibacterial cream.

In case of inhalation, the victim should be allowed to rest in a well-ventilated area. If inhalation is severe, the victim should be evacuated to a safe area as soon as possible and tight clothing (shirt collar, belts, or tie) loosened.

If the victim finds it difficult to breathe, oxygen should be administered. In the extreme case of not breathing, mouth-to-mouth resuscitation is performed. Of course, it must be taken into account that it can be dangerous for the person providing help when the inhaled material is toxic, infectious or corrosive.

If swallowed, do not induce vomiting, loosen clothing, and if victim is not breathing, perform mouth-to-mouth resuscitation.

In all cases, immediate medical attention should be sought (Material Safety Data Sheet Iodic acid, 2013).

Uses and health benefits

Iodic acid is commonly used as a standardizing agent for solutions of weak and strong bases. It is a strong acid that is used in analytical chemistry to carry out titrations.

It is used with the methyl red or methyl orange indicators to perform equivalence point readings in titrations.

It is used in the salt industry to synthesize sodium or potassium iodate salt. By using this iodic acid compound in the preparation of the salt, the iodine content of the salt is increased (Omkar Chemicals, 2016).

This compound has long been used for organic synthesis since it has the ability to selectively oxidize organic compounds, given its action to perform equivalent partial oxidation analysis, a useful technique for determining structures (Roger J. Williams, 1937).

Iodine and iodic acid are used as an efficient combination of reagents for the iodination of aryl hydroxy ketones. In the work of (Bhagwan R. Patila, 2005), a variety of ortho-hydroxy substituted aromatic carbonyl compounds were regioselectively iodinated with iodine and iodic acid with excellent yields.


  1. Bhagwan R. Patila, SR (2005). Iodine and iodic acid: an efficient reagent combination for iodination of aryl hydroxy ketones. Tetrahedron Letters Volume 46, Issue 42, 7179–7181.
  2. IODIC ACID. (SF). Retrieved from chemicalland21:
  3. Material Safety Data Sheet Iodic acid. (2013, May 21). Retrieved from sciencelab:
  4. National Center for Biotechnology Information. (SF). PubChem Compound Database; CID = 24345. Retrieved from PubChem.
  5. Omkar Chemicals. (2016, June 11). NATURE OF IODIC ACID AND ITS USES IN VARIOUS PURPOSES. Retrieved from Omkar Chemicals Official Blog:
  6. Roger J. Williams, MA (1937). THE SELECTIVITY OF IODIC ACID IN THE OXIDATION OF ORGANIC COMPOUNDS. journal of american chemical society 59 (7), 1408-1409. 
  7. Royal Society of Chemistry. (2015). Iodic acid. Retrieved from chemspider:

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