Хлорид серебра: свойства, применение и история

Chemical compound with the formula AgCl
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| ImageFile = Chlorid stříbrný. PNG
| ImageFile1 = Silver chloride 3D ionic. png
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| IUPACName = Silver(I) chloride
| OtherNames = CerargyriteChlorargyriteHorn silver Argentous chloride
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| Section4 = Chembox Thermochemistry
| DeltaHf = −127 kJ·mol−1
| Entropy = 96 J·mol−1·K−1

Silver chloride has been known since ancient times. Ancient Egyptians produced it as a method of refining silver, which was done by roasting silver ores with salt to produce silver chloride, which was subsequently decomposed to silver and chlorine. Silver chloride, historically known as luna cornea (which could be translated as "horn silver" as the moon was an alchemic codename for silver), Later in 1816, the use of silver chloride was introduced into photography by Nicéphore Niépce.

The solid adopts the fcc NaCl structure, in which each Ag+ ion is surrounded by an octahedron of six chloride ligands. AgF and AgBr crystallize similarly. However, the crystallography depends on the condition of crystallization, primarily free silver ion concentration, as is shown in the picture to the left (greyish tint and metallic lustre are due to partially reduced silver). Above 7.5 GPa, silver chloride transitions into a monoclinic KOH phase. Then at 11 GPa, it undergoes another phase change to an orthorhombic TlI phase. Then the sulfate is protonated in the presence of sulfuric acid to bisulfate, which can be reversed by dilution. This reaction is used to separate silver from other platinum group metals.

Silver chloride and silver nitrate have been used in photography since it began, and are well known for their light sensitivity. Another famous process that used silver chloride was the gelatin silver process where embedded silver chloride crystals in gelatin were used to produce images. However, with advances in color photography, these methods of black and white photography have dwindled. Even though color photography uses silver chloride, it only works as a mediator for transforming light into organic image dyes. Other photographic uses include making photographic paper, since it reacts with photons to form latent images via photoreduction; and in photochromic lenses, taking advantage of its reversible conversion to Ag metal. Unlike photography, where the photoreduction is irreversible, the glass prevents the electron from being 'trapped'. These photochromic lenses are used primarily in sunglasses. The antimicrobial activity of silver chloride depends on the particle size, but are usually below 100 nm. In general, silver chloride is antimicrobial against various bacteria, such as E. coli. Silver chloride nanoparticles for use as a microbial agent can be produced by a metathesis reaction between aqueous silver and chloride ions or can be biogenically synthesized by fungi and plants.

Silver chloride occurs naturally as chlorargyrite in the arid and oxidized zones in silver deposits. If some of the chloride ions are replaced by bromide or iodide ions, the words bromian and iodian are added before the name, respectively. This mineral is a source of silver and is leached by cyanidation, where it will produce the soluble [Ag(CN)2]– complex.