Hydroiodic Acid Formula

What is Hydroiodic Acid Formula?

The hydroiodic acid chemical formula is also called the Hydrogen iodide formula. It is the aqueous solution of hydrogen iodide. When the hydrogen iodide gas is dissolved in water, the Hydroiodic Acid is obtained. In its anhydrous form, it is a molecule that is made up of an iodine atom and a hydrogen atom. The molecular or chemical formula of Hydroiodic Acid is HI.

It is a colourless liquid, having an acrid odour. It is odourless and holds a cooling and saline pungent cooling taste. It can be prepared commercially by reacting iodine with hydrazine that gives nitrogen gas and hydrogen iodide. The hydroiodic acid symbol of the chemical formula hydroiodic acid is Hl.

Hydroiodic Acid Formula and Structure

Hydrogen iodide is polarized because of the electronegative nature of iodide. Furthermore, because of the huge size of the iodide ion, the negative charge scatters and this results in a weaker H-I bond. And, this permits the H+ to be easily dissociated and thus, HI is given as a stronger acid if we compare it with HBr, HCl and the HF.

HI is the chemical formula for hydroiodic acid. Furthermore, it holds a molar mass of 127.91 g/mol. The hydrogen iodide is present in the gaseous state, while hydroiodic acid is present in the form of an aqueous solution of the HI. These both are interchangeable. Moreover, an image exhibiting its chemical structure is given below in the common representations, which we generally use for the organic molecules:

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Hydroiodic acid reacts with the oxygen in the air to form iodine:

4 HI + O2 → 2 H

2O + 2 I2

Similar to other hydrogen halides, hydroiodic acid adds to alkenes to produce alkyl iodides. Also, it can be used as a reducing agent, for instance, in the reduction of aromatic nitro compounds to anilines.

Cativa Process

The Cativa process is a primary end use of hydroiodic acid that serves as a co-catalyst for the acetic acid production by the carbonylation of methanol.

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Illicit Uses

Hydroiodic acid can be listed as a United States Federal DEA List I Chemical, owing to its use as a reducing agent and related to the production of methamphetamine from pseudoephedrine or ephedrine (recovered from the nasal decongestant pills).


Physical Properties

The hydrogen iodide is described as a gas having an acrid odour, which has no colour and is soluble easily when we keep it inside the water to provide hydroiodic acid. Also, basically, the “Concentrated” hydroiodic acid is 48% - 57% (HI) inside the water. However, it is exact and points to point the physical properties such as the melting point, boiling point, and density depends upon the HI concentration in the aqueous solution.

Chemical Properties

Hydroiodic acid is defined as a strong and reactive acid. Due to its powerful reactivity, it should be used carefully. It may react violently with metal powders, ammonia, and so on to generate explosions and fire. It is highly corrosive and strongly reacts with bases. Also, HI decomposes on heating to generate toxic fumes and gets oxidized in the air rapidly.

Hl is used to write the formula for hydroiodic acid.

FAQs on Hydroiodic Acid Formula

Q1. Give Some Uses of Hydroiodic Acid?

Answer: The most common use of the element is to prepare alkyl iodides. It is an important class of organic compounds by the process of reacting to the HI either with the alkenes or the primary alcohols. Hydroiodic acid (Hl) is a common reducing agent for multiple industrial purposes as well.

Q2. What are the Health Hazards and Health Effects Associated With Hydroiodic Acid?

Answer: In nature, HI gas is toxic by inhalation and it can be highly irritating to the skin, to the eyes and the mucous membranes in humans. Also, hydroiodic acid may result in eye damages and severe skin burns. Further, it is highly toxic if we ingest it or inhale it or absorb it through our skin.