Ammonium bromide


Ammonium bromide
Ammonium bromide
Identifiers
CAS number 12124-97-9 YesY
ChemSpider 23804 YesY
UNII R0JB3224WS YesY
RTECS number BO9155000
Jmol-3D images Image 1
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 GHS-pictogram-exclam.svg[1]
GHS hazard statements H319[1]
GHS precautionary statements P305+351+338
EU Index Not listed
NFPA 704
NFPA 704.svg
0
2
0
Related compounds
Other anions Ammonium fluoride
Ammonium chloride
Ammonium iodide
Other cations Sodium bromide
Potassium bromide
 YesY bromide (verify) (what is: YesY/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).

Contents

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

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