HBr
Hydrogen bromide · Hydrobromic acid
Hydrogen bromide is a stable, insulating diatomic compound widely used as a critical reagent in industrial and laboratory chemical synthesis.
About Hydrogen bromide
Hydrogen bromide is a simple diatomic molecule that exists as a thermodynamically stable phase. Its electronic structure is characterized by a wide band gap, classifying it as an insulating material in its solid state. Due to its high reactivity and solubility, it serves as a foundational chemical building block.
This compound is widely utilized in synthetic chemistry, particularly for the production of organobromine derivatives. Its stability on the convex hull underscores its reliability as a precursor in various industrial processes, ranging from flame retardants to pharmaceutical manufacturing.
Key Properties
Cross-validated computational properties for Hydrogen bromide, aggregated across 3 databases.
Band GapEnergy needed to move an electron from the valence band to the conduction band. Lower or zero values tend to behave more metallic; larger gaps are more insulating or semiconducting.
Energy Above HullThermodynamic distance from the most stable set of competing phases. 0 eV/atom is on the convex hull; small positive values may still be experimentally accessible.
StabilityA plain-language summary of the best reported energy-above-hull result. It reflects whether the lowest-energy structure is on, near, or far from the stability hull.
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of HBr. Tight agreement means computed properties can be trusted without re-running calculations.
Agreement ScoreA normalized confidence score summarizing how closely independent DFT databases agree. Higher scores mean tighter cross-source agreement.
Hull SpreadDifference between the highest and lowest energy-above-hull values reported by comparable sources. Smaller spread means less thermodynamic disagreement.
Sources ComparedNumber and names of computational sources with comparable entries for this formula.
Space Group ConsensusWhether independent sources predict the same crystal symmetry for the lowest-energy structure.
Reported Structures
Lowest-energy structures reported for HBr, ranked by energy above hull.
| Space GroupSymmetry classification of the crystal arrangement. The number is the international space-group index. | Crystal SystemBroad lattice family, such as cubic, tetragonal, monoclinic, or triclinic, derived from unit-cell symmetry. | Band Gap (eV)Electronic gap calculated for this specific reported structure, measured in electronvolts. | E above hull (eV/atom)Thermodynamic distance from the convex hull for this structure, normalized per atom. Lower is generally more stable. | E/atom (eV)Computed total energy normalized per atom. Use energy above hull, not this value alone, when comparing stability. | Density (g/cm³)Mass per relaxed crystal volume, reported in grams per cubic centimeter. |
|---|---|---|---|---|---|
| Cmc21 (No. 36) | orthorhombic | 4.94 | 0.0000 | -3.033 | 2.80 |
| — | — | 4.75 | 0.0000 | -0.398 | — |
| Cmc21 (No. 36) | orthorhombic | 4.67 | 0.0000 | -0.185 | — |
| Pnma (No. 62) | orthorhombic | 4.66 | 0.0003 | -0.185 | — |
| Pnma (No. 62) | orthorhombic | 5.34 | 0.0004 | -3.033 | 2.78 |
| — | — | 4.68 | 0.0043 | -0.394 | — |
| P212121 (No. 19) | orthorhombic | 4.49 | 0.0226 | -3.011 | 2.44 |
| — | — | 4.47 | 0.0471 | -0.351 | — |
| Cm (No. 8) | monoclinic | 1.60 | 0.2955 | -2.738 | 2.33 |
| — | — | 1.11 | 0.3078 | -0.090 | — |
| I4/mmm (No. 139) | tetragonal | 1.55 | 0.3089 | -2.724 | 2.10 |
| Fmmm (No. 69) | orthorhombic | 1.48 | 0.3104 | -2.723 | 2.33 |
Applications
Where Hydrogen bromide is used.
Patent Landscape
6 patents reference HBr or close compositional variants.
| Patent | Title | Assignee | Granted |
|---|---|---|---|
| 6890508 | Preparation of largely HBr-free HCI gas and largely HBr-free aqueous HCI solution | — | — |
| 4203813 | Method for producing HBr | — | — |
| 6008140 | Copper etch using HCI and HBr chemistry | — | — |
| 4830846 | Separation process for anhydrous HCl and HBr by thermal cleavage | — | — |
| 5986149 | Method for recovering alkanols from aqueous HBr-solutions | — | — |
| 4218301 | Apparatus for producing HBr utilizing a consumable bromine electrode | — | — |
Frequently Asked Questions
Common questions about Hydrogen bromide, answered from cross-validated data.
What is HBr?
Hydrogen bromide is a stable, insulating diatomic compound widely used as a critical reagent in industrial and laboratory chemical synthesis.
What is HBr used for?
What is the band gap of HBr?
Is HBr a metal, semiconductor, or insulator?
Is HBr thermodynamically stable?
What is the crystal structure of HBr?
How many polymorphs of HBr are known?
What elements does HBr contain?
Where does the data for HBr come from?
How It Compares
As a fundamental hydrogen halide, hydrogen bromide occupies a central role in chemical synthesis. Unlike more complex inorganic salts, its simplicity allows for high-purity applications in industrial catalysis and organic functionalization.
Data sources & attribution
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- oqmd — Data from the OQMD (oqmd.org). Cite: Saal et al., JOM 65, 1501 (2013); Kirklin et al., npj Comp. Mater. 1, 15010 (2015). (CC-BY-4.0)
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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