Bromic acid
Skeletal model of bromic acid
Spacefill model of bromic acid
Names
IUPAC name
Bromic acid
Other names
Bromic(V) acid
Hydrogen bromate
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.029.235 Edit this at Wikidata
EC Number
  • 232-158-3
25861
MeSH Bromic+acid
UNII
  • InChI=1S/BrHO3/c2-1(3)4/h(H,2,3,4) checkY
    Key: SXDBWCPKPHAZSM-UHFFFAOYSA-N checkY
  • InChI=1/BrHO3/c2-1(3)4/h(H,2,3,4)
    Key: SXDBWCPKPHAZSM-UHFFFAOYAE
  • O[Br+2]([O-])[O-]
  • O=Br(=O)O
Properties
BrHO3
Molar mass 128.909 g·mol−1
Acidity (pKa) −2
Conjugate base Bromate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Bromic acid, also known as hydrogen bromate, is an oxoacid with the molecular formula HBrO3. It only exists in aqueous solution.[1][2] It is a colorless solution that turns yellow at room temperature as it decomposes to bromine.[1][3] Bromic acid and bromates are powerful oxidizing agents and are common ingredients in Belousov–Zhabotinsky reactions.[3][4] Belousov-Zhabotinsky reactions are a classic example of non-equilibrium thermodynamics.

Dissociation

Low concentrations dissociate completely to hydronium and bromate while high concentrations decompose to form bromine. Bromic acid's high instability can be explained because the positively charged hypervalent bromine is connected to the electronegative OH group.[5]

Structure

There are several isomers of HBrO3.[5][6] The calculated bond lengths are listed below based on three high level theories G2MP2, CCSD(T), and QCISD(T).[5]

Species HOOOBr HOOBrO HOBrO2 HBrO3
Br–O bridged (Å) 1.867 1.919 1.844 —
Br–O terminal (Å) — 1.635 1.598 1.586

The large energy barriers between these structures do not make isomerization possible. HOBrO2 is the most stable isomer and is the one pictured above.[6]

Synthesis

Bromic acid is the product of a reaction of barium bromate and sulfuric acid.[1]

Ba(BrO3)2 + H2SO4 → 2 HBrO3 + BaSO4

Barium sulfate is insoluble in water and forms a precipitate. The aqueous bromic acid can be decanted removing the barium sulfate.

References

  1. ^ a b c The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals. 14th Edition. 2006.
  2. ^ Van Nostrand's Scientific Encyclopedia. Glenn D. Considine. Ninth Edition. Volume 1. p 554
  3. ^ a b Recipes for Belousov–Zhabotinsky reagents. J. Chem. Educ., 1991, 68 (4), 320. doi:10.1021/ed068p320
  4. ^ The Source of the Carbon Monoxide in the Classical Belousov–Zhabotinsky Reaction. J. Phys. Chem. A., 2007, 111 (32), 7805–12 doi:10.1021/jp073512+
  5. ^ a b c Theoretical investigation of halogen-oxygen bonding and its implications in halogen chemistry and reactivity. Bioinorganic Chemistry and Applications, 2007, 1, 11/1–11/9
  6. ^ a b A Theoretical Examination of the Isomerization Pathways for HBrO3 Isomers. J. Phys. Chem. A, 2000, 104 (41), 9321-27. doi:10.1021/jp001604s
Categories