Ammonium Bromide

Ammonium bromide, NH4Br, is the ammonium salt of hydrobromic acid.
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 (Br-) to bromine (Br2).

PREPARATION

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