What Is Ammonium Iodide?
Ammonium iodide is an inorganic compound with the chemical formula NH4l.
It is a white crystalline compound that is deliquescent, and its crystals gradually turn yellow due to the release of iodine by decomposition. Its molecular weight is 144.94 g/mol and its density is 2.514 g/cm³. It has a high melting point of 551°C and a boiling point of 235°C, but it sublimates and decomposes before boiling.
It is well soluble in water, and its solubility increases with increasing temperature. It is also soluble in ethanol, methanol, acetone, and glycerin. Experimentally, ammonium iodide is a liquid obtained by neutralizing hydroiodic acid (a solution of hydrogen iodide) with ammonia or ammonium carbonate.
Industrially, it is produced by reacting hydroiodic acid (HI) with ammonia (NH3) in water. It is also used in a wide range of applications, such as medicine, photographic development, and organic synthesis.
Uses of Ammonium Iodide
Due to its unique properties, ammonium iodide is used in a variety of fields, including pharmaceuticals, photosensitizers, and organic synthesis reagents.
1. Medical Applications
Ammonium iodide is used medicinally as an expectorant, an application that promotes the expulsion of mucus from the airways. It is also used in the treatment of thyroid disorders due to its ability to reduce the size of the thyroid gland.
2. Photo Sensitizer
Used as a sensitizer for silver halide emulsions used in X-ray films and photographic plates in the development of photographs.
3. Organic Synthesis Reagent
Ammonium iodide is widely used as a reagent in organic synthesis reactions. Specifically, it is used in the synthesis of organo-halogen compounds and iodine compounds. It is also used as a solvent for a variety of other reactions. Ammonium Iodide is one of the most widely used reagents in synthetic organic chemistry because it is inexpensive and readily available.
Properties of Ammonium Iodide
Ammonium Iodide is a white crystalline compound with the chemical formula NH4I. Iodine is released upon decomposition by moisture in the air, and the final color gradually turns yellow.
Its molecular weight is 144.94 g/mol and its density is 2.514 g/cm³. It has a high melting point of 551°C and a boiling point of 235°C, but it sublimates and decomposes before boiling.
Ammonium iodide is very soluble in water, and its solubility increases with increasing temperature. It dissolves well in ethanol and acetone, but is insoluble in ether. Ammonium iodide decomposes upon heating to form ammonia gas (NH3) and hydrogen iodide gas (HI).
Structure of Ammonium Iodide
The chemical structure of ammonium iodide is composed of an ammonium cation (NH4+) and an iodide anion (I-). The ammonium ion has a tetrahedral shape with a nitrogen atom in the center and hydrogen atoms at the four corners.
The iodide anion is a negatively charged halide ion with a halogen atom bonded to a nonmetal atom.
Other Information on Ammonium Iodide
How Ammonium Iodide Is Produced
Ammonium iodide is produced by the reaction of hydroiodic acid (HI) with ammonia (NH3) in water.
NH3(g) + HI(aq) → NH4I(s)
The reaction is exothermic and is usually carried out under reflux conditions to increase yield. The resulting solution can be concentrated to precipitate crystals of Ammonium Iodide.
The resulting ammonium iodide solid is usually washed with cold water to remove impurities and dried under vacuum. Ammonium Iodide can also be prepared by neutralizing hydroiodic acid with ammonium carbonate.
(NH4)2CO3(aq) + 2HI (aq) → 2NH4I(s) + CO2(g) + H2O(l)
However, this method is less common than the direct reaction of ammonia with hydroiodic acid.