Bromide compounds, especially potassium bromide, were frequently used as sedatives in the 19th and early 20th century. This gave the word "bromide" its colloquial connotation of a boring cliché, a bit of conventional wisdom overused as a sedative.
One can test for a bromide ion by adding dilute nitric acid (HNO3), then silver nitrate (AgNO3). A cream precipitate forms that disappears in concentrated ammonia solution.
Bromide is present in typical seawater (35 PSU) with a concentration of aroud 65 mg/l, which is around 0.2% of all dissolved salts.
Ammonium bromide, NH4Br, is a substance used in manufacturing photographic chemicals and emulsion. It is also used as a flame retardant.
Ammonium bromide can be prepared by the direct action of hydrogen bromide on ammonia. The chemical crystallizes in colourless prisms, possessing a saline taste; it sublimes on heating and is easily soluble in water. On exposure to air it gradually assumes a yellow colour and becomes acid in its reaction.
Potassium bromide is a typical ionic salt which is fully dissociated and near pH 7 in aqueous solution. It serves as a source of bromide ions- this reaction is important for the manufacture of silver bromide for photographic film: KBr(aq) + AgNO3(aq) potassium fluoride, potassium fluoborate, tin fluoborate, copper fluoborate, potassium bi fluoride, ammonium silico fluoride, potassium silico fluoride AgBr(s) + KNO3(aq)
Aqueous bromide Br- will also form complexes when reacted with some metal halides such as copper(II) bromide: 2 KBr(aq) + CuBr2(aq) potassium fluoride, potassium fluoborate, tin fluoborate, copper fluoborate, potassium bi fluoride, ammonium silico fluoride, potassium silico fluoride K2[CuBr4](aq).
Sodium bromide is a salt with the formula NaBr, widely used as an anticonvulsant and a sedative in the late 19th and early 20th centuries. Its action is due to the bromide ion (potassium bromide is equally effective). It is a high-melting white, crystalline solid that resembles sodium chloride. It is a widely used source of the bromide ion.
