Silver Chloride - Chemistry

Chemistry

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:

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, K_sp, for AgCl is 1.77 × 10−10 M2, which indicates that one liter of water will dissolve 1.3 × 10−5 moles (1.9 mg) of AgCl at room temperature. 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 K_sp 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.