Silver chloride is a

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbol ...

Ag Cl. This white

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macro ...

line solid is well known for its low

solubility In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solub ...

water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...

(this behavior being reminiscent of the chlorides of Tl⁺ and Pb²⁺). Upon illumination or heating, silver chloride converts to silver (and chlorine), which is signaled by grey to black or purplish coloration to some samples. AgCl occurs naturally as a mineral chlorargyrite.

Preparation

Silver chloride is unusual in that, unlike most

chloride The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the element chlorine (a halogen) gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride sa ...

salts, it has very low solubility. It is easily synthesized by metathesis: combining an aqueous solution of

silver nitrate Silver nitrate is an inorganic compound with chemical formula . It is a versatile precursor to many other silver compounds, such as those used in photography. It is far less sensitive to light than the halides. It was once called ''lunar causti ...

(which is soluble) with a soluble chloride salt, such as sodium chloride or

cobalt(II) chloride Cobalt(II) chloride is an inorganic compound of cobalt and chlorine, with the formula . The compound forms several hydrates ·''n'', for ''n'' = 1, 2, 6, and 9. Claims of the formation of tri- and tetrahydrates have not been confirmed.M. T. Saug ...

. The silver chloride that forms will precipitate immediately. :AgNO3 + NaCl -> AgCl(v) + NaNO3 :2 AgNO3 + CoCl2 -> 2 AgCl(v) + Co(NO3)2

Structure and reactions

The solid adopts the ''fcc''

NaCl Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35.45 g/ ...

structure, in which each Ag⁺ ion is surrounded by an

octahedron In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at ea ...

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 on the pictures left (greyish tint and metallic lustre are due to partly reduced

silver Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...

). AgCl dissolves in solutions containing

ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elec ...

s such as

cyanide Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms. In chemistry, a cyanide () is a chemical compound that contains a functional group. This group, known as the cyano group, consists of ...

triphenylphosphine Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to P Ph3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists ...

, thiosulfate,

thiocyanate Thiocyanate (also known as rhodanide) is the anion . It is the conjugate base of thiocyanic acid. Common derivatives include the colourless salts potassium thiocyanate and sodium thiocyanate. Mercury(II) thiocyanate was formerly used in pyr ...

and

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...

. Silver chloride reacts with these ligands according to the following illustrative equations: :AgCl (s) + Cl^- (aq) -> AgCl2^- (aq) :AgCl (s) + 2 S2O3^2- (aq) ->(Ag(S2O3)2)^3- (aq) + Cl^- (aq) :AgCl (s) + 2 NH3(aq) -> Ag(NH3)2+ (aq) + Cl^- (aq) Silver chloride does not react with nitric acid. Most complexes derived from AgCl are two-, three-, and, in rare cases, four-coordinate, adopting linear, trigonal planar, and tetrahedral coordination geometries, respectively. :3AgCl(s) + Na3AsO3(aq) -> Ag3AsO3(s) + 3NaCl(aq) :3AgCl(s) +Na3AsO4(aq) -> Ag3AsO4(s) + 3NaCl(aq) Above 2 reactions are particularly important in qualitative analysis of AgCl in labs as AgCl is white in colour, which changes to Ag3AsO3 (silver arsenite) which is yellow in colour or Ag3AsO4( Silver arsenate) which is reddish brown in colour.

Chemistry

In one of the most famous reactions in chemistry, addition of colorless aqueous

to an equally colorless solution of sodium chloride produces an opaque white precipitate of AgCl: :Ag+ (aq) + Cl^- (aq) -> AgCl (s) This conversion is a common test for the presence of

in solution. Due to its conspicuousness it is easily used in titration, which gives the typical case of

argentometry In analytical chemistry, argentometry is a type of titration involving the silver(I) ion. Typically, it is used to determine the amount of chloride present in a sample. The sample solution is titrated against a solution of silver nitrate of known co ...

. The

solubility product Solubility equilibrium is a type of dynamic equilibrium that exists when a chemical compound in the solid state is in chemical equilibrium with a solution of that compound. The solid may dissolve unchanged, with dissociation, or with chemical reacti ...

, ''K''_sp, for AgCl in water is at room temperature, which indicates that only 1.9 mg (that is,

\sqrt \ \mathrm

) of AgCl will dissolve per liter of water. The chloride content of an aqueous solution can be determined quantitatively by weighing the precipitated AgCl, which conveniently is non-hygroscopic, since AgCl is one of the few transition metal chlorides that is unreactive toward water. Interfering ions for this test are bromide and iodide, as well as a variety of ligands (see silver halide). For AgBr and AgI, the ''K''_sp values are 5.2 x 10⁻¹³ and 8.3 x 10⁻¹⁷, respectively. Silver bromide (slightly yellowish white) and silver iodide (bright yellow) are also significantly more photosensitive than is AgCl. AgCl quickly darkens on exposure to light by disintegrating into elemental

chlorine Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...

and metallic

. This reaction is used in photography and film.

Uses

*The

silver chloride electrode A silver chloride electrode is a type of reference electrode, commonly used in electrochemical measurements. For environmental reasons it has widely replaced the saturated calomel electrode. For example, it is usually the internal reference el ...

is a common reference electrode in

electrochemistry Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, with the potential difference as an outco ...

. *Silver chloride's low solubility makes it a useful addition to pottery glazes for the production of "Inglaze lustre". *Silver chloride has been used as an antidote for mercury poisoning, assisting in the elimination of mercury. *Silver chloride is used: ** to make photographic paper since it reacts with photons to form

latent image {{citations needed, date=November 2015 A latent image is an invisible image produced by the exposure to light of a photosensitive material such as photographic film. When photographic film is developed, the area that was exposed darkens and form ...

and via photoreduction ** in

photochromic lens A photochromic lens is an optical lens that darkens on exposure to light of sufficiently high frequency, most commonly ultraviolet (UV) radiation. In the absence of activating light, the lenses return to their clear state. Photochromic lenses may ...

es, again taking advantage of its reversible conversion to Ag metal ** in

bandage A bandage is a piece of material used either to support a medical device such as a dressing or splint, or on its own to provide support to or to restrict the movement of a part of the body. When used with a dressing, the dressing is applie ...

s and wound healing products ** to create yellow, amber, and brown shades in stained glass manufacture ** as an

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

transmissive optical component as it can be hot-pressed into window and lens shapes ** as an antimicrobial agent: *** in some personal deodorant products *** for long-term preservation of drinking water in water tanks

References

{{DEFAULTSORT:Silver Chloride Chlorides Silver compounds Metal halides Coordination complexes Photographic chemicals Light-sensitive chemicals Rock salt crystal structure

Preparation

Structure and reactions

Chemistry

Uses

See also

References