Hydrogen bromide
| Names | |
|---|---|
| IUPAC name
Hydrogen bromide
| |
| Other names
Anhydrous hydrobromic acid
| |
| Identifiers | |
| Jmol-3D images | Image |
| |
| Properties | |
| HBr | |
| Molar mass | 80.91 g/mol |
| Appearance | Colorless gas Brownish gas (impure) |
| Odor | Acrid |
| Density | 3.6452 kg/m3 (At 0 °C, 1013 mbar) |
| Melting point | −86.9 °C (−124.4 °F; 186.2 K) |
| Boiling point | −66.8 °C (−88.2 °F; 206.3 K) |
| 221 g/100 mL (0 °C) 204 g/100 mL (15 °C) 193 g/100 mL (20 °C) 130 g/100 mL (100 °C) | |
| Solubility | Reacts with amines Soluble in alcohols |
| Vapor pressure | 2.308 MPa (at 21 °C) |
| Acidity (pKa) | ~–9 |
| Thermochemistry | |
| Std molar
entropy (S |
198.696-198.704 J·K−1·mol−1 |
| Std enthalpy of
formation (ΔfH |
-36.45--36.13 kJ·mol−1 |
| Hazards | |
| Safety data sheet | Praxair |
| Lethal dose or concentration (LD, LC): | |
| LC50 (Median concentration)
|
2858 ppm (rat, 1 hr) 814 ppm (mouse, 1 hr) |
| Related compounds | |
| Related compounds
|
Hydrogen chloride Hydrogen iodide |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Hydrogen bromide is a gaseous corrosive compound with the chemical formula HBr. When dissolved in water, the solution is known as hydrobromic acid.
Contents
Properties
Chemical
Hydrogen bromide reacts with metals such as magnesium or aluminium to yield their respective bromides.
Reaction with ammonia in gaseous phase will result in a very fine ammonium bromide mist.
Physical
Hydrogen bromide is a colorless gas, though in the presence of light it will slowly turn yellow-brownish, due to traces of bromine. It is extremely soluble in water, as well as alcohols and other organic solvents. Hydrogen bromide has an unpleasant acrid smell.
Availability
Anhydrous hydrogen bromide is only sold to industrial entities.
Preparation
Reaction of diluted sulfuric acid with a bromide salt yields hydrobromic acid, which can be dehydrated through a variety of methods to hydrogen bromide, however it may decompose to form small amounts of elemental bromine.
A much better method involves the bromination of tetralin:
- C10H12 + 4 Br2 → C10H8Br4 + 4 HBr[1]
Lastly reacting hydrogen and bromine gas under light will also yield anhydrous hydrogen bromide.[2] This reaction is much less dangerous than that between hydrogen and chlorine.
All the bromide traces from the described processes can be removed by passing the impure hydrogen bromide though a layer of phenol or or through copper turnings at high temperature, in the absence of oxygen.
Projects
- Make anhydrous bromide salts
Handling
Safety
Hydrogen bromide is extremely corrosive and dangerous for lungs, mouth, nose and eyes if inhaled.
Storage
Anhydrous hydrogen bromide should be stored in special containers, in a separate location.
Disposal
Gaseous hydrogen bromide can be neutralized with ammonia, though this will generate a mist of ammonium bromide. A better way is to react it with a base or sodium thiosulfate.
References
- ↑ M. Schmeisser "Chlorine, Bromine, Iodine" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 282.
- ↑ http://www.orgsyn.org/demo.aspx?prep=cv2p0338
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- Chemical compounds
- Inorganic compounds
- Hydrogen compounds
- Corrosive chemicals
- Bromides
- Gases
- Irritants
