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Names | |||
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IUPAC name
Hydrogen bromide
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Preferred IUPAC name
Bromane[1] | |||
Identifiers | |||
3D model (JSmol)
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3587158 | |||
ChEBI | |||
ChEMBL | |||
ChemSpider | |||
ECHA InfoCard | 100.030.090 | ||
EC Number |
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KEGG | |||
MeSH | Hydrobromic+Acid | ||
PubChem CID
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RTECS number |
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UNII | |||
UN number | 1048 | ||
CompTox Dashboard (EPA)
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Properties | |||
HBr | |||
Molar mass | 80.91 g/mol | ||
Appearance | Colorless gas | ||
Odor | Acrid | ||
Density | 3.307 g/L (25 °C)[2] | ||
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 | Soluble in alcohol, organic solvents | ||
Vapor pressure | 2.308 MPa (at 21 °C) | ||
Acidity (pKa) | −8.8 (±0.8);[3] ~−9[4] | ||
Basicity (pKb) | ~23 | ||
Conjugate acid | Bromonium | ||
Conjugate base | Bromide | ||
Refractive index (nD)
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1.325[citation needed] | ||
Structure | |||
Linear | |||
820 mD | |||
Thermochemistry | |||
Heat capacity (C)
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350.7 mJ/(K·g) | ||
Std molar
entropy (S⦵298) |
198.696–198.704 J/(K·mol)[5] | ||
Std enthalpy of
formation (ΔfH⦵298) |
−36.45...−36.13 kJ/mol[5] | ||
Hazards | |||
Occupational safety and health (OHS/OSH): | |||
Main hazards
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Highly corrosive | ||
GHS labelling: | |||
Danger | |||
H314, H335 | |||
P261, P280, P305+P351+P338, P310 | |||
NFPA 704 (fire diamond) | |||
Lethal dose or concentration (LD, LC): | |||
LC50 (median concentration)
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2858 ppm (rat, 1 h) 814 ppm (mouse, 1 h)[7] | ||
NIOSH (US health exposure limits): | |||
PEL (Permissible)
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TWA 3 ppm (10 mg/m3)[6] | ||
REL (Recommended)
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TWA 3 ppm (10 mg/m3)[6] | ||
IDLH (Immediate danger)
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30 ppm[6] | ||
Safety data sheet (SDS) | hazard.com | ||
Related compounds | |||
Related compounds
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Hydrogen fluoride Hydrogen chloride Hydrogen iodide Hydrogen astatide | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Hydrogen bromide is the inorganic compound with the formula HBr. It is a hydrogen halide consisting of hydrogen and bromine. A colorless gas, it dissolves in water, forming hydrobromic acid, which is saturated at 68.85% HBr by weight at room temperature. Aqueous solutions that are 47.6% HBr by mass form a constant-boiling azeotrope mixture that boils at 124.3 °C (255.7 °F). Boiling less concentrated solutions releases H2O until the constant-boiling mixture composition is reached.
Hydrogen bromide, and its aqueous solution, hydrobromic acid, are commonly used reagents in the preparation of bromide compounds.