Silver nitrate (Lunar caustic) AgNO3

Silver nitrate is prepared by dissolving silver in dilute nitric acid.

3Ag + 4HNO3 ------> 3AgNO3 + 2H2O + NO

Silver nitrate on heating decomposes to form silver, nitrogen dioxide and oxygen.

2AgNO3 ---------> 2AgNO2 + O2

AgNO2 ---------> Ag + NO2

Silver nitrate is also decomposed by organic matter, such as glucose, paper, skin and cork. It has also a caustic and destructive effect on organic tissues.

Uses of silver nitrate
Large quantities of silver nitrate are used in the production of light sensitive plates, film and papers. In the laboratory it is used as a reagent for the detection of halide ions. It is used in making inks and hair dyes. In small doses, silver nitrate is used as a medicine for nervous diseases.

Silver halides
Silver fluorides may be prepared by the action of hydrofluoric acid on silver(1) oxide.

Ag2O + 2HF -------> 2AgF + H2O

Silver chloride, silver bromide and silver iodide are prepared by the action of silver nitrate on sodium halide.

Ag+ + x+ --------> AgX
(Where X = Cl, Br or I)

Ie Ag+ + Cl- --------> AgCl


Silver fluoride is soluble in water whereas the silver chloride, silver bromide and iodide are insoluble in water.
Silver chloride is highly soluble in ammonia solution due to the formation of Diammine silver(1) chloride complex [Ag(NH3)2]Cl.
Silver bromide is slightly soluble in ammonia solution and silver iodide insluble in ammonia solution.
All the silver halides dissolve in thiosulphate to form thiosulphate complex of silver and in cyanide solution to form dicyano complexes of silver(1).

Uses of silver halides
Silver chloride is used in photography for making printing paper. Silver bromide is used for the production of films and plates in photography and silver iodide used for the production of colloidal emulsion plates in photography.

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