Silver chloride

Silver chloride
Names
IUPAC name
Silver(I) chloride
Other names
cerargyrite
chlorargyrite
horn silver
Identifiers
7783-90-6 Yes
ChEBI CHEBI:30341 Yes
ChemSpider 22967 Yes
Jmol-3D images Image
PubChem 24561
RTECS number VW3563000
UNII MWB0804EO7 Yes
Properties
Molecular formula
 AgCl
Molar mass 143.32 g·mol−1
Appearance White Solid
Density 5.56 g cm−3
Melting point 455 °C (851 °F; 728 K)
Boiling point 1,547 °C (2,817 °F; 1,820 K)
520 μg/100 g at 50 °C
Solubility soluble in NH3, conc. HCl, conc. H2SO4, alkali cyanide, NH4CO3?, KBr, Na2S2O3;

insoluble in alcohol, dilute acids.

2.071
Structure
Crystal structure halite
Thermochemistry
96 J·mol−1·K−1[1]
Std enthalpy of
formation (ΔfHo298)
 −127 kJ·mol−1[1]
Hazards
MSDS Salt Lake Metals
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
0
2
0
Related compounds
Other anions
 silver(I) fluoride, silver bromide, silver iodide
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Silver chloride is a chemical compound with the chemical formula AgCl. This white crystalline solid is well known for its low solubility in water (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 greyish or purplish coloration to some samples. AgCl occurs naturally as a mineral chlorargyrite.

Preparation

Silver chloride is easily synthesized by combining aqueous solutions of silver nitrate and sodium chloride.

AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq)

Structure and reactions

Silver Chloride Crystals
Pyramidal Crystals of AgCl

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.[2] 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). AgCl dissolves in solutions containing ligands such as chloride, cyanide, triphenylphosphine, thiosulfate, thiocyanate and ammonia. Silver chloride reacts with these ligands according to the following illustrative equations:

AgCl(s) + Cl−(aq) → AgCl2−(aq)
AgCl(s) + 2S2O32−(aq) → [Ag(S2O3)2]3−(aq) + Cl−(aq)
AgCl(s) + 2NH3(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.

Chemistry

Silver chloride decomposes over time with exposure to UV light

In one of the most famous reactions in chemistry, addition of colorless aqueous silver nitrate to an equally colorless solution of sodium chloride produces an opaque white precipitate of AgCl:[3]

Ag+(aq) + Cl−(aq) → AgCl(s)

This conversion is a common test for the presence of chloride in solution. Due to its conspicuousness it is easily used in titration, which gives the typical case of argentometry.

The solubility product, Ksp, for AgCl in water is 1.77 × 10−10 at room temperature, which indicates that only 1.9 mg (\sqrt{1.77 * 10^{-10}} moles) of AgCl will dissolve in each 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. Ions that interfere with this test are bromide and iodide, as well as a variety of ligands (see silver halide). For AgBr and AgI, the Ksp values are 5.2 x 10−13 and 8.3 x 10−17, respectively. The silver bromide (slightly yellowish white) and silver iodide (pale yellow) are also significantly more photosensitive than is AgCl.

AgCl quickly darkens on exposure to light by disintegrating into elemental chlorine and metallic silver. This reaction is used in photography and film.

Uses

References

  1. ↑ 1.0 1.1 Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A23. ISBN 0-618-94690-X.
  2. ↑ Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.
  3. ↑ More info on Chlorine test
  4. ↑ Crystran Data Sheet and Application