Ammonium bromide
| Ammonium bromide | |
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Ammonium bromide |
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| Identifiers | |
| CAS number | 12124-97-9  |
| ChemSpider | 23804 |
| UNII | R0JB3224WS |
| RTECS number | BO9155000 |
| Jmol-3D images | Image 1 |
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| 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
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| Related compounds | |
| Other anions | Ammonium fluoride Ammonium chloride Ammonium iodide |
| Other cations | Sodium bromide Potassium bromide |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| 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).
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[edit] 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
[edit] 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
[edit] 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]
[edit] References
- ^ a b Online Sigma Catalogue , accessdate: June 10, 2011.
- ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
