Ammonium bromide, NH₄Br, is the

ammonium salt The ammonium cation is a positively-charged polyatomic ion with the chemical formula or . It is formed by the protonation of ammonia (). Ammonium is also a general name for positively charged or protonated substituted amines and quaternary ...

hydrobromic acid Hydrobromic acid is a strong acid formed by dissolving the diatomic molecule hydrogen bromide (HBr) in water. "Constant boiling" hydrobromic acid is an aqueous solution that distills at and contains 47.6% HBr by mass, which is 8.77 mol/L. ...

. The chemical crystallizes in colorless prisms, possessing a saline taste; it sublimes on heating and is easily soluble in water. On exposure to air it gradually assumes a yellow color because of the oxidation of traces of

bromide A bromide ion is the negatively charged form (Br−) of the element bromine, a member of the halogens group on the periodic table. Most bromides are colorless. Bromides have many practical roles, being found in anticonvulsants, flame-retardant ...

(Br⁻) to

bromine Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table ( halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simi ...

(Br₂).

Preparation

Ammonium bromide can be prepared by the direct action of

hydrogen bromide Hydrogen bromide is the inorganic compound with the formula . It is a hydrogen halide consisting of hydrogen and bromine. A colorless gas, it dissolves in water, forming hydrobromic acid, which is saturated at 68.85% HBr by weight at room tempe ...

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...

. : 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

Reactions

Ammonium bromide is a weak acid with a pKa of ~5 in water. It is an

acid salt Acid salts are a class of salts that produce an acidic solution after being dissolved in a solvent. Its formation as a substance has a greater electrical conductivity than that of the pure solvent. An acidic solution formed by acid salt is made dur ...

because the ammonium ion hydrolyzes slightly in water. Ammonium Bromide is strong electrolyte when put in water: :NH₄Br(s) → NH₄⁺(aq) + Br⁻(aq) Ammonium bromide decomposes to ammonia and

when heated at elevated temperatures: : NH₄Br → NH₃ + HBr

Uses

Ammonium bromide is used for photography in films, plates and

paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distrib ...

s; in fireproofing of wood; in

lithography Lithography () is a planographic method of printing originally based on the immiscibility of oil and water. The printing is from a stone (lithographic limestone) or a metal plate with a smooth surface. It was invented in 1796 by the German a ...

and process engraving; in corrosion inhibitors; and in pharmaceutical preparations.Pradyot Patnaik. ''Handbook of Inorganic Chemicals''. McGraw-Hill, 2002,

References

{{bromides Ammonium compounds Bromides Nonmetal halides