Ammonium bromide

Ammonium bromide
IUPAC name Ammonium bromide
Identifiers
CAS number	12124-97-9 Y
ChemSpider	23804 Y
UNII	R0JB3224WS Y
RTECS number	BO9155000
Jmol-3D images	Image 1
SMILES [Br-].[NH4+]
InChI InChI=1S/BrH.H3N/h1H;1H3 Y Key: SWLVFNYSXGMGBS-UHFFFAOYSA-N Y InChI=1/BrH.H3N/h1H;1H3 Key: SWLVFNYSXGMGBS-UHFFFAOYAP
Properties
Molecular formula	NH4Br
Molar mass	97.94 g/mol
Appearance	white powder, hygroscopic
Density	2.429 g/cm3
Melting point	452 °C, 725 K, 846 °F
Solubility in water	60.6 g/100 mL (0 °C) 78.3 g/100 mL (25 °C) 145 g/100 mL (100 °C)
Refractive index (nD)	1.712
Structure
Crystal structure	Isometric
Hazards
GHS pictograms	[1]
GHS hazard statements	H319[1]
GHS precautionary statements	P305+351+338
EU Index	Not listed
NFPA 704	0 2 0
Related compounds
Other anions	Ammonium fluoride Ammonium chloride Ammonium iodide
Other cations	Sodium bromide Potassium bromide
Y bromide (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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

Reactions

Ammonium bromide is a weak acid with a pKa 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 at elevated temperatures:

NH₄Br → NH₃ + HBr

Uses

Ammonium bromide is used for photography in films, plates and papers; in fireproofing of wood; in lithography and process engraving; in corrosion inhibitors; and in pharmaceutical preparations.^[2]

References

1. ^ ^{a b} Online Sigma Catalogue , accessdate: June 10, 2011.
2. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8