Silver Bromide Formula

Silver Bromide Formula

Silver bromide is an important light sensitive compound which is used in many photographic applications.

Formula and structure: The chemical formula of silver bromide is AgBr and its molar mass is 187.77 g/mol. It is an inorganic compound made up of the silver metal (Ag) and the bromine atom (Br), held together through a polar covalent bond which has a strong ionic character. Similar to the other silver halides, solid AgBr also has a face-centered cubic structure similar to that of NaCl.

Occurrence: Silver bromide occurs naturally as the mineral bromargyrite in considerable amounts. However, it is typically obtained in large amounts through chemical production.

Preparation: Silver bromide is prepared industrially by the reaction between aqueous solutions of silver nitrate and potassium bromide. The water-insoluble silver bromide product precipitates out at the end of the reaction, while the potassium nitrate by-product remains in the solution.

AgNO3 + KBr → AgBr + KNO3

Physical properties: Silver bromide is found as a pale-yellow odorless solid. It has a density of 6.473 g/mL, melting point of 432 °C and boiling point of 1,502 °C. It is insoluble in water.

Chemical properties: Silver bromide is characterized by its photosensitive property (absorbs energy from light). It reacts when exposed to light and turns grey or black. Thus, it needs to be stored in the dark. It reacts readily with liquid ammonia to form various amine complexes. It is a stable compound under normal conditions, but when heated to high temperatures, it decomposes with the release of toxic fumes of bromine.

Uses: Due to its light sensitive nature, the main applications of silver bromide are in photography. It is used in photographic films and plates. It is also used for infrared applications, for light sensitive eyeglasses, and semiconductors. Like some other silver halides, it also has antiseptic properties and is used as a topical disinfectant and astringent.

Health effects/safety hazards: Silver bromide is not a particularly hazardous material. Upon skin or eye contact, it can cause irritation and greyish discoloration, similar to many other silver compounds. Inhalation can result in sneezing, coughing, and difficulty in breathing. Swallowing large amounts can cause tissue discoloration and affect the central nervous system and kidneys.

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