Silver+sulfide

**Silver Sulfide**

Molar Mass: 247.8 g/mol Molecular Formula: Ag2S Apperance: Black, cubic crystal Density: 7.23 g/cm3 Melting Point: 1098K Solubility: Soluble in Nitric Acid and Sulfuric Acid Hazard: Irritation

Silver sulfide, Ag2S, is the sulfide of silver. This dense black solid constitutes the tarnish that forms over time on silverware and other silver objects. Silver sulfide is insoluble in all solvents, but is degraded by strong acids. Silver sulfide features a covalent bond, as it is made up of silver (electronegativity of 1.98) and sulfur (electronegativity of 2.58). It is a component of classical qualitative inorganic analysis. When formed on electrical contacts operating in an atmosphere rich in hydrogen sulfide, long filaments known as silver whiskers can form. __**Structure**__

Three forms are known: monoclinic acanthite, stable below 500 °C, body centered cubic so-called argentite, stable above 176 °C, and a high temperature face-centred cubic form stable above 586 °C.[3home] The higher temperature forms are electrical conductors.[3home] It is found in nature as relatively low temperature mineral acanthite. The name argentite refers to a cubic form, which, due to instability in "normal" temperatures, is found in form of the pseudomorphosis of acanthite after argentite. Acanthite is an important ore of silver. Ag2S is used as a photosensitizer in photography- []