TCC’s Ammonium Bromide is the ammonium salt of hydrobromic acid. The chemical formula is NH4Br. The chemical crystallizes into colorless prisms, possessing a saline taste; it sublimes on heating and is easily soluble in water. On exposure to air ammonium bromide gradually assumes a yellow color because of the oxidation of traces of bromide (Br) to bromine (Br2).
Ammonium bromide can be prepared by the direct action of hydrogen bromide on ammonia.
NH3 + HBr → NH4Br
It can also be prepared by the reaction of ammonia with iron(II) bromide or iron(III) bromide, which may be obtained by passing aqueous bromine solution over iron filings.
2 NH3 + FeBr2 + 2 H2O → 2 NH4Br + Fe(OH)2
Ammonium bromide is a weak acid with a pH of ~5 in water. It is an acid salt because the ammonium ion hydrolyzes slightly in water.
Ammonium bromide decomposes to ammonia and hydrogen bromide when heated to elevated temperatures:
NH4Br → NH3 + HBr