por He bromic acidalso known as hydrogen bromate or bromic (V) acid, is a chemical compound with the formula HBrO3. It is an oxacid of bromine with a structure analogous to chloric acid (EMBL-EBI, 2014). The compound is a very strong acid. Its structure is presented in Figure 1 (EMBL-EBI, 2008).
To prepare bromic acid, a soluble bromate is usually dissolved in water and a soluble barium salt is added. Slightly soluble barium bromate precipitates.
The barium bromate can then be dissolved in water and acidified with sulfuric acid to precipitate the basically insoluble barium sulfate and leave the bromic acid behind (see image above):
2KBrO3(aq) + BaCl2(aq) —> Ba(BrO3)2(s) + 2KCl(aq)
Ba(BrO3)2(aq) + H2SO4(aq) —> 2HBrO3 + BaSO4
The compound can also be produced by the decomposition of bromine pentachloride in alkaline solution according to the reaction:
BrCl5 + 3 H2O → HBrO3 + 5 HCl
Bromic acid is a strong oxidizing agent. The bromate ion can be further oxidized with elemental fluorine or xenon difluoride in the presence of base, the oxidation accompanied by small explosions and the Teflon tube caught on fire (My Favorite Chemicals, SF).
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Physical and chemical properties of bromic acid
Bromic acid exists only in a colorless solution (up to 50% w/v) that turns yellowish on contact with air (National Center for Biotechnology Information., 2017). Its appearance is shown in figure 2.
The compound has a molecular weight of 128.91 g/mol and decomposes at 100 °C and has a pKa of -2. Being an unstable compound, its physicochemical properties were obtained through computational calculations.
It has a melting point of 206.04 °C, a boiling point of 517.26 °C and a solubility in water of 1 x 106 mg/l at 25 °C (Royal Society of Chemistry, 2015).
The compound is a strong oxidizing agent. When mixed with ethanol or ether, it decomposes to form acetic acid in an exothermic reaction. It is fundamental for the elaboration of bromate salts (BrO3-) that are prepared by reacting the carbonates or oxides of metals with bromic acid (Watts, 1870).
Reactivity and hazards
Bromic acid is an unstable compound decomposing to elemental bromine. Being a strong acid, it is extremely dangerous in case of contact with the skin (corrosive and irritant), in contact with the eyes (irritant) and in case of ingestion. Very dangerous too, in case of inhalation.
Severe overexposure can cause lung damage, suffocation, unconsciousness, or death. Prolonged exposure can cause skin burns and ulcerations. Overexposure by inhalation may cause respiratory irritation.
Inflammation of the eye is characterized by redness, watering, and itching. Inflammation of the skin is characterized by itching, scaling, redness, and occasionally blistering.
The substance is toxic to the kidneys, lungs and mucous membranes. Repeated or prolonged exposure to the substance may cause damage to these organs.
In case of contact with eyes
Check if contact lenses are being worn and remove them immediately. Eyes should be flushed with running water for at least 15 minutes, keeping the eyelids open. Cold water can be used. Eye ointment should not be used.
In case of skin contact
If the chemical comes into contact with clothing, remove it as quickly as possible, protecting your own hands and body. Place the victim under a safety shower.
If the chemical accumulates on the victim’s exposed skin, such as the hands, gently and carefully wash the contaminated skin with running water and a non-abrasive soap. Cold water can be used. If irritation persists, seek medical attention. Wash the contaminated clothing before using it again.
If skin contact is severe, wash with a disinfectant soap and cover contaminated skin with an antibacterial cream.
In case of inhalation
It is advisable to let the victim rest in a well-ventilated area. If inhalation is severe, the victim should be evacuated to a safe area as soon as possible. Loosen tight clothing such as shirt collars, belts, or ties. If the victim finds it difficult to breathe, oxygen should be administered.
If the victim is not breathing, mouth-to-mouth resuscitation is performed. Always taking into account that it can be dangerous for the person providing help to give mouth-to-mouth resuscitation when the inhaled material is toxic, infectious or corrosive.
If swallowed, do not induce vomiting. Loosen tight clothing such as shirt collars, belts, or ties. If the victim is not breathing, perform mouth-to-mouth resuscitation.
In all cases immediate medical attention should be sought.
Applications
Bromic acid is used as a powerful oxidizing agent in laboratory reactions. It is used to produce chemical compounds such as iodates, chloric acid, tetrahonic acid, among others.
It is also used for the production of bromates such as iron, lead, manganese, and mercury bromate, among others.
Bromic acid acts as an important intermediate in the Bélousov-Zhabotinsky reaction (Morris, 2010). This reaction is an example of chemical clocks and illustrates a non-thermodynamic equilibrium reaction.
The oscillation reaction is catalyzed by cerium and is inherently connected to the chemistry of the bromine oxoacids HBrOx. The growing interest in nonlinear chemical systems has provided strong incentives to study bromine chemistry.
In the Belousov-Zhabotinsky reaction, the bromine compounds involved are hypobromous acid HOBr, bromous acid HOBrO and bromic acid HBrO3 (3) (Rainer Glaser, 2013).
These kinds of reactions are important to theoretical chemistry. They show that chemical reactions do not have to be dominated by equilibrium thermodynamic behavior.
References
Bromic Acid. (SF). Retrieved from chemyq.com.
EMBL-EBI. (2008, May 16). bromic acid. Retrieved from ebi.ac.uk.
EMBL-EBI. (2014, July 28). chloric acid. Retrieved from ebi.ac.uk.
Morris, S. (2010, January 23). Belousov Zhabotinsky reaction 8 x normal speed. Retrieved from youtubecom.
My Favorite Chemicals. (SF). Recovered from bromicacid.com.
National Center for Biotechnology Information. (2017, March 11). PubChem Compound Database; CID=24445, . Retrieved from PubChem.
Rainer Glaser, MD (2013). Why the Acidity of Bromic Acid Really Matters for Kinetic Models of Belousov-Zhabotinsky Oscillating Chemical Reactions. Journal of Thermodynamics & Catalysis 4:1.
Royal Society of Chemistry. (2015). Bromic acid. Retrieved from chemspider.com.
Watts, H. (1870). A Dictionary of Chemistry and Allied Branches of Other Sciences, Volume 1. London: longmans, green and co.