Chemical Properties
Silver bromide, AgBr, is pale yellow crystals or powder, that darken on exposure to light, finally turning black and soluble in potassium bromide, potassium cyanide, and sodium thiosulfate solutions, only very slightly soluble in ammonia water, insoluble in water, and light sensitive. Derivation is through silver nitrate dissolving in water and a solution ofalkali bromide added slowly. The precipitated silver bromide is washed repeatedly with hotwater. The operation must be carried on in a darkroom under a ruby-red light. Used in photographic film and plates, photochromic glass and as a laboratory reagent.
Physical properties
Yellow cubic crystals or powder; refractive index 2.253; darkens on exposure to light; Mohs hardness 2.5; density 6.47g/cm
3; melts at 432°C; vaporizes at 1,502°C; insoluble in water, alcohol, and most acids; slightly soluble in dilute ammonia and ammonium carbonate solutions; sparingly soluble in concentrated ammonia solution (0.33 g/100mL 10% ammonia solution at 12°C);soluble in alkali cyanide solutions.
Uses
Silver Bromide is used in the spectroscopic study of silver halides in montmorillonite and their antibacterial activity, also used in the antimicrobial compositions for use in wound care products.
Uses
A yellowish powder made by the combination of any soluble
bromide with silver nitrate. Silver bromide could also be
formed by exposing metallic silver to the fumes of bromine
as in the daguerreotype process. It is soluble in sodium thiosulfate,
potassium bromide, and potassium cyanide solutions.
Silver bromides were secondary halides for the paper negative
processes, albumen negative process, and wet or preserved
collodion processes. Silver bromides were the primary halides
for the silver bromide collodion emulsion negative and the
silver bromide gelatin emulsion processes. Silver bromide is
the most photosensitive silver halide.
Preparation
Silver bromide is prepared by double decomposition reaction. An aqueous solution of alkali bromide, such as sodium or potassium bromide, is slowly added to an aqueous solution of silver nitrate:
Ag+ (aq) + Brˉ (aq) → AgBr(s)
The precipitate is washed repeatedly with hot water. Preparation should be in a dark room under a ruby red light.
Flammability and Explosibility
Non flammable
Purification Methods
It is insoluble in dilute HNO3 or dilute NH3 but is soluble in conc NH3. Store it in the dark.
