Hypobromous Acid (Properties, Uses)

Hypobromous acid, with the chemical formula HOBr and the bromine atom in the +1-oxidation state, is a weak, unstable acid. It is used as a disinfectant, oxidizer, cleaner, and deodorant since it has the ability to destroy viruses and bacteria. In certain respects, hypobromite is similar to hypochlorite, and it can also be used as a germicide and an ant parasitic. Aqueous solutions are used to manufacture and treat hypobromous acid. As a disinfectant, it is produced both biologically and commercially. Hypobromite salts are only occasionally isolated as solids.

A disproportionation reaction produces hypobromous acid and hydrobromic acid (HBr) when bromine is added to water.

Br2 + H2O HOBr + HBr

Bromoperoxidases, enzymes that catalyze the oxidation of bromide with hydrogen peroxide, contain hydrobromous acid in nature:

Br + H2O2 HOBr + OH

Space-filling model of hypobromous acid

It only exists in solution and shares many of the same chemical and physical properties as hypochlorous acid, HClO. Hypobromous acid only partly dissociates into the hypobromite anion BrO- and the cation H+ in aqueous solution. With a pKa of 8.65, hypobromous acid is only partly dissociated in water at pH 7 and has a boiling point of 20 to 25°C. Hypobromite salts, including acids, are unstable and undergo a slow disproportionation reaction to produce bromate and bromide salts.

3 BrO(aq) → 2 Br(aq) + BrO3 (aq)

It has similar chemical and physical properties to other hypohalites. Because of its ability to kill and finish the cells of many pathogens, the HOBr is useful as a cleaner, an oxidizer, a deodorant, and a disinfectant. Furthermore, the compound is produced by warm-blooded vertebrate organisms, especially eosinophils.

Bromide is also used as a germicidal agent in hot tubs and spas, with an oxidizing agent generating hypobromite in a similar way to eosinophils’ peroxidase. When combined with its congener, hypochlorous acid, it is particularly effective. Hypobromites are the salts of hypobromous acid. These salts, like the acid, are unstable and undergo a disproportionation reaction when evaporated or boiled to dryness, yielding the respective bromate and bromide salts.

Information Sources:

  1. chemicalbook.com
  2. toppr.com
  3. wikipedia