Potassium bromate is produced when bromine is passed through a hot solution of potassium hydroxide. This first forms unstable potassium hypobromite, which quickly disproportionates into bromide and bromate:[2]
3BrO−(aq) → 2Br−(aq) + BrO−
3(aq)
Electrolysis of potassium bromide solutions will also give bromate. Both processes are analogous to those used in the production of chlorates.
Potassium bromate is readily separated from the potassium bromide present in both methods owing to its much lower solubility; when a solution containing potassium bromate and bromide is cooled to 0°C, nearly all bromate will precipitate, while nearly all of the bromide will stay in solution.[2]