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).

Ammonium bromide
Names
IUPAC name
Ammonium bromide
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.031.973
EC Number
  • 235-183-8
RTECS number
  • BO9155000liugoiugiu
UNII
Properties
NH4Br
Molar mass 97.94 g/mol
Appearance white powder, hygroscopic
Density 2.429 g/cm3
Melting point 235 °C (455 °F; 508 K)
Boiling point 452 °C (846 °F; 725 K)
60.6 g/100 mL (0 °C)
78.3 g/100 mL (25 °C)
145 g/100 mL (100 °C)
−47.0·10−6 cm3/mol
1.712
Structure
Isometric
Hazards
GHS pictograms [1]
GHS Signal word Warning
H315, H319, H335[1]
P261, P264, P271, P280, P302+352, P304+340, P305+351+338, P312, P321, P332+313, P337+313, P362, P403+233, P405, P501
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
0
2
0
Related compounds
Other anions
 Ammonium fluoride
Ammonium chloride
Ammonium iodide
Other cations
 Sodium bromide
Potassium bromide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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 is strong electrolyte when put in water:

NH4Br(s) → NH4+(aq) + Br−(aq)

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. Sigma-Aldrich Co., Ammonium bromide. Retrieved on 2013-07-20.
  2. Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8

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