Ammonium bromide

Ammonium bromide

Ammonium bromide, with the chemical formula NH_4Br, is an inorganic compound consisting of ammonium cations (NH_4^+) and bromide anions (Br^-). It is a white crystalline solid that is highly soluble in water. Ammonium bromide is used in various applications, including photography, pharmaceuticals, and as a flame retardant.

Properties

Ammonium bromide is a hygroscopic compound, meaning it readily absorbs moisture from the environment. It has a melting point of 452 °C (846 °F) and decomposes before boiling. In aqueous solution, it dissociates into ammonium and bromide ions.

Synthesis

Ammonium bromide can be synthesized by the direct combination of ammonia (NH_3) with hydrobromic acid (HBr). The reaction is as follows: \[ NH_3(g) + HBr(g) \rightarrow NH_4Br(s) \]

It can also be produced by the reaction of ammonia with bromine water, although this method is less common.

Applications

Photography

In photography, ammonium bromide is used as a component of photographic emulsions to increase the sensitivity of photographic film and paper.

Pharmaceuticals

In the pharmaceutical industry, it has been used as a sedative and an expectorant, although its use has declined due to the development of more effective and safer alternatives.

Flame Retardants

Ammonium bromide is used as a flame retardant in some polymers and textiles. It works by releasing hydrogen bromide, a fire-inhibiting gas, when heated.

Safety

Ammonium bromide is generally considered safe for handling and use in most applications. However, it should be stored in a cool, dry place away from incompatible substances such as strong acids and bases. Inhalation of dust or mist can cause respiratory irritation, and contact with the skin or eyes may cause irritation.

Environmental Impact

As with all chemicals, the environmental impact of ammonium bromide should be considered. It is relatively benign, but its release into waterways should be avoided to prevent potential harm to aquatic life.