Chemistry Formulas

Ammonium Bromide Formula

Ammonium Bromide Formula

Ammonium bromide (NH4Br) is the ammonium salt of hydrobromic acid. The chemical matures in prisms that are colorless, owning a salty taste. It sublimes when heated and is very easily soluble in the water. On exposure to the air, it slowly assumes a color because of the oxidation of traces of the bromide (Br−) to the bromine (Br2) and the color assumed by this is yellow. In a simple language, the ammonium bromide is the odorless crystals that are white in color or the granules which turn into yellow color when exposed with air. The ammonium bromide formula stays stable under the recommended storage conditions that have a set temperature according to the need of the ammonium bromide.

Structural Formula of Ammonium Bromide

Ammonium Bromide is generally an ammonium salt that is formed when an ammonium ion reacts with bromide ion in a ratio of 1:1.

NH3 + HBr → NH4Br

The structural representation of Ammonium Bromide is provided below:

ammonium bromide formula


Ammonium bromide can be formed by the process of a direct action of the hydrogen bromide on the ammonia. The preparation of the Ammonium bromide can also be done by the process of reacting to the ammonia with iron (II) bromide or iron (III) bromide, which we can attain by passing the aqueous bromine solution over the iron filings.

2 NH3 + FeBr2 + 2 H2O → 2 NH4Br + Fe(OH)2


Ammonium bromide is a weak type of acid that has a pKa of ~5 in the water. It is an acid salt. The reason that it is an acid salt is that the ammonium ion hydrolyzes slightly inside the water. Ammonium Bromide is a strong electrolyte when it is present inside the water.

NH4Br(s) → NH4+(aq) + Br−(aq)

The Ammonium bromide gets decomposed to the ammonia and hydrogen bromide when it gets heated at raised temperature levels.

NH4Br → NH3 + HBr


Ammonium Bromide is useful for the purpose of photography in the films, plates, and papers, in fireproofing of the wooden elements, in the lithography and the process inscription, in the corrosion inhibitors, and in many pharmaceutical preparations done in the labs during the experiments.

Ammonium Bromide is also used in combination with an appropriate oxidizer and it is an efficient biocide that is applied in various water systems in the industrial sector and wastewater to control bacteria, fungi, and the algae.


Some important details related to the ammonium bromide such as chemical formula, molecular weight, density, crystal structure, chemical names, boiling point, and melting point are :

The chemical formula of the ammonium bromide is NH4Br or it can also be called BrH4N. Further, the Molecular weight of the ammonium bromide is 97.943 g/mol. The density of the ammonium bromide is 2.429 g/cm3. The crystal structure of the ammonium bromide is Isometric.

Similarly, some Chemical Names given to the ammonium bromide are Ammonii bromide, Ammonium bromatum, and the Ammonium bromide ((NH4)Br). The Boiling point of the ammonium bromide is near about 452 °C whereas the melting point of the ammonium bromide is 235 °C.


In water, the solubility of the ammonium bromide is 78.3 g/100 g water at 25 °C. It is soluble in acetone, ammonia, ether, in water, 97 g/100 cc at 25 °C, 145.6 g/100 cc at 100 °C; in alcohol, 10 g/100 cc at 78 °C. It is freely soluble in the methanol, ethanol, and acetone, slightly soluble in ether and practically insoluble in the ethyl acetate.


The density of the ammonium bromide is 2.429 at 68 °F (USCG, 1999) and 2.429 at 25 °C of temperature level.

Solved Example on Ammonium Bromide Formula

Question: What reaction occurs when we dissolve NH4Br in the water?

  1. NH4+ + OH- <==> NH4OH
  2. Br-+ H3O <==> HBr+ H2O
  3. NH3+H2O <==>NH4+OH
  4. NH4+H2O <==> NH3+H3O+
  5. Br+ H2O <==> HBr+ OH

Solution: NH4Br is the salt of a weak base, NH4OH and a strong acid HBr at the same time, Thus, the NH4+ will hydrolyze as given below:

NH4+ + H2O ==> NH3 + H3O+, so option D is the correct answer.

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