Bromic acid, also known as hydrogen bromate, is an
oxoacid
An oxyacid, oxoacid, or ternary acid is an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bonded to oxygen that can dissociate to produce ...
with the molecular formula HBrO
3. It only exists in
aqueous solution
An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), in water would be re ...
.
[''The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals''. 14th Edition. 2006.][''Van Nostrand's Scientific Encyclopedia''. Glenn D. Considine. Ninth Edition. Volume 1. p 554] It is a colorless solution that turns yellow at room temperature as it decomposes to
bromine
Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table (halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simila ...
.
[Recipes for Belousov–Zhabotinsky reagents. ''J. Chem. Educ.'', 1991, 68 (4), 320. DOI]
10.1021/ed068p320
/ref> Bromic acid and bromate
The bromate anion, BrO, is a bromine-based oxoanion. A bromate is a chemical compound that contains this ion. Examples of bromates include sodium bromate, (), and potassium bromate, ().
Bromates are formed many different ways in municipal drinki ...
s are powerful oxidizing agents and are common ingredients in Belousov–Zhabotinsky reaction
A Belousov–Zhabotinsky reaction, or BZ reaction, is one of a class of reactions that serve as a classical example of non-equilibrium thermodynamics, resulting in the establishment of a nonlinear chemical oscillator. The only common element in ...
s.[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+
/ref> Belousov-Zhabotinsky reactions are a classic example of non-equilibrium thermodynamics
Non-equilibrium thermodynamics is a branch of thermodynamics that deals with physical systems that are not in thermodynamic equilibrium but can be described in terms of macroscopic quantities (non-equilibrium state variables) that represent an ext ...
.
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.[Theoretical investigation of halogen-oxygen bonding and its implications in halogen chemistry and reactivity. ''Bioinorganic Chemistry and Applications'', 2007, 1, 11/1–11/9]
Structure
There are several isomers of HBrO3.[A Theoretical Examination of the Isomerization Pathways for HBrO3 Isomers. ''J. Phys. Chem. A'', 2000, 104 (41), 9321-27. DOI]
10.1021/jp001604s
/ref> The calculated bond lengths are listed below based on three high level theories G2MP2, CCSD(T), and QCISD(T).[
The large energy barriers between these structures do not make isomerization possible. HOBrO2 is the most stable isomer and is the one pictured above.][
]
Synthesis
Bromic acid is the product of a reaction of barium bromate and sulfuric acid.[
:
Barium sulfate is insoluble in water and forms a precipitate. The aqueous bromic acid can be decanted removing the barium sulfate.
]
References
{{Authority control
Bromates
Halogen oxoacids
Mineral acids
Oxidizing acids