The ammonium iodide is the chemical compound NH4I that comes in use in the photographic chemicals and also in some medications at the same time. The preparation of the ammonium iodide takes place by the action of hydroiodic acid on the ammonia. It is easily soluble when we mix it in the water (H2O). Moreover, by the process of mixing it with the water, it crystallizes in the shape of cubes. It is also soluble when putting inside the solution of ethanol and then, as a result, it turns yellow on standing in the moist air, owing to decomposition with the process of liberation of the iodine. Read on further to know about Ammonium Iodide Formula.
Structure and Formula
The molecular formula of the ammonium iodide is H4IN and its structure is present below in the form of an image:
Firstly we dissolve 254 grams of the potassium iodide in 125 ml of water (H2O) and mix it with 100 grams of ammonium sulfate. Then we have to dissolve in 125 ml of boiling water. After it cools down, we add 40 ml of alcohol and then we keep the mixture for a time period of 12 hours.
However, then we obtain a precipitate of potassium sulfate that we filter and then we evaporate the filtrate occasionally by adding ammonia water that is containing some amount of alcohol until the process of crystallization starts. Then the crystals of the potassium sulfate are additionally washed with the dilute alcohol that is about 20 percent. Moreover, after combining the filtrates and evaporating finally the ammonium iodide is obtained as a result.
(NH4)2SO4+ 2KI →2NH4I + K2SO4
The ammonium iodide crystallizes in the shape of cubes and deliquesces in the air. We have to preserve it in a dark place because the light decomposes the salt, causing it to turn brown in color. We can remove this coloration by dissolving it in distilled water.
After that, then treating the solution with the ammonium sulfide, filtering, and evaporating the filtrate with the help of the steam bath, to crystallize. It is readily soluble in alcohol. The aqueous solution turns yellow in color on standing, owing to the decomposition and separation of the iodine. One part of the salt dissolves in 0.60 parts of the water (H2O).
The ammonium iodide can also be made in a laboratory. By the process of reacting ammonia or ammonium hydroxide with the hydroiodic acid or the hydrogen iodide gas:
NH3+ HI → NH4I
NH4OH + HI → NH4I + H2O
The ammonium iodide is useful in many ways and one of them is in photographic chemicals. Moreover, we also generally use it in the process of making various types of medicines.
The ammonium iodide is visible in the form of a white crystalline powder. In addition, it has a melting point of 551 °C whereas, it has a boiling point of 405 °C. Its molar mass is 144.94 g/mol with a density of 2.51 g/cm³. It is easily soluble when putting inside the water (H2O).
Safety and Health Hazards
Due to the inhalation of the ammonium iodide a person may suffer from multiple health issues, some of them are irritation of nose and throat. Contact of the ammonium iodide with the naked eyes of a living being can cause irritation in the eyes. The toxic and irritating fumes of the hydrogen iodide, iodine, and oxides of nitrogen may result in the fire. The compound may sublime into the fire and then condense on the cold surfaces. The ammonium iodide should be kept in a tightly closed and protected container and the sunlight should not enter that container.
Solved Example on Ammonium Iodide Formula
Question: How to prepare methyl ammonium iodide for lead iodide perovskite?
Solution: Addition of CH3NH2 and HI at ice-cold conditions then stir for 2 h, followed by heating at 80-90oC for 3 h, eventually, you will get while solid. This one should go for washing with ether multiple times and dried in an oven at 600C for one day.
In detail, you can find in nature paper about the preparation of CH3NH3I.