Silver sulfide

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Silver sulfide
Ball-and-stick model of silver sulfide
Sample of silver sulfide
Names
IUPAC name
Silver(I) sulfide
Other names
Silver sulfide
Argentous sulfide
Identifiers
3D model (
JSmol
)
ChemSpider
ECHA InfoCard
 100.040.384 Edit this at Wikidata
EC Number
  • 244-438-2
UNII
  • InChI=1S/2Ag.S/q2*+1;-2 ☒N
    Key: XUARKZBEFFVFRG-UHFFFAOYSA-N ☒N
  • [S-2].[Ag+].[Ag+]
Properties
Ag2S
Molar mass 247.80 g·mol−1
Appearance Grayish-blackish crystal
Odor Odorless
Density 7.234 g/cm3 (25 °C)[1][2]
7.12 g/cm3 (117 °C)[3]
Melting point 836 °C (1,537 °F; 1,109 K)[1]
6.21·10−15 g/L (25 °C)
6.31·10−50
Solubility Soluble in aq. HCN, aq. citric acid with KNO3
Insoluble in acids, alkalies, aqueous ammoniums[4]
Structure
Cubic, cI8 (α-form)
Monoclinic, mP12 (β-form)
Cubic, cF12 (γ-form)[3][5]
Im3m, No. 229 (α-form)[5]
P21/n, No. 14 (β-form)
Fm3m, No. 225 (γ-form)[3]
2/m (α-form)[5]
4/m 3 2/m (β-form, γ-form)[3]
a = 4.23 Å, b = 6.91 Å, c = 7.87 Å (α-form)[5]
α = 90°, β = 99.583°, γ = 90°
Thermochemistry
76.57 J/mol·K[6]
143.93 J/mol·K[6]
Std enthalpy of
formation
(ΔfH⦵298)
 −32.59 kJ/mol[6]
−40.71 kJ/mol[6]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 May cause irritation
GHS labelling:
GHS07: Exclamation mark[2]
Warning
H315, H319, H335[2]
P261, P305+P351+P338[2]
NFPA 704 (fire diamond)
[7]
NFPA 704 four-colored diamondHealth 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g. sodium chlorideFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
0
0
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Silver sulfide is an inorganic compound with the formula Ag
2S. A dense black solid, it is the only sulfide of silver. It is useful as a photosensitizer in photography. It constitutes the tarnish that forms over time on silverware and other silver objects. Silver sulfide is insoluble in most solvents, but is degraded by strong acids. Silver sulfide is a network solid made up of silver (electronegativity of 1.98) and sulfur (electronegativity of 2.58) where the bonds have low ionic character (approximately 10%).

Formation

Silver sulfide naturally occurs as the tarnish on silverware. When combined with silver, hydrogen sulfide gas creates a layer of black silver sulfide patina on the silver, protecting the inner silver from further conversion to silver sulfide.[8] Silver whiskers can form when silver sulfide forms on the surface of silver electrical contacts operating in an atmosphere rich in hydrogen sulfide and high humidity.[9] Such atmospheres can exist in sewage treatment and paper mills.[10][11]

Structure and properties

Three

pseudomorphosis
of acanthite after argentite.

History

In 1833 Michael Faraday noticed that the resistance of silver sulfide decreased dramatically as temperature increased. This constituted the first report of a semiconducting material.[13]

Silver sulfide is a component of classical qualitative inorganic analysis.[14]

References

  1. ^
    ISBN 978-1-4200-9084-0
    .
  2. ^ a b c d Sigma-Aldrich Co., Silver sulfide. Retrieved on 2014-07-13.
  3. ^
    ISBN 978-2-88124-761-3
    .
  4. ^ Comey, Arthur Messinger; Hahn, Dorothy A. (February 1921). A Dictionary of Chemical Solubilities: Inorganic (2nd ed.). New York: The MacMillan Company. p. 835.
  5. ^
    ISBN 978-3-540-31360-1
    .
  6. ^
    ISBN 978-0-07-049439-8
    .
  7. ^ "MSDS of Silver Sulfide". saltlakemetals.com. Utah, USA: Salt Lake Metals. Archived from the original on 2014-08-10. Retrieved 2014-07-13.
  8. ISBN 978-1-111-58065-0
    .
  9. ^ "Degradation of Power Contacts in Industrial Atmosphere: Silver Corrosion and Whiskers" (PDF). 2002.
  10. PMID 20163816
    .
  11. ^ "Control of Hydrogen Sulfide Generation | Water & Wastes Digest". www.wwdmag.com. 5 March 2012. Retrieved 2018-07-05.
  12. ^ Frueh, A. J. (1958). The crystallography of silver sulfide, Ag2S. Zeitschrift für Kristallographie-Crystalline Materials, 110(1-6), 136-144.
  13. ^ "1833 - First Semiconductor Effect is Recorded". Computer History Museum. Retrieved 24 June 2014.
  14. ISBN 978-0-08-037941-8
    .

External links
Wikimedia Commons has media related to Silver sulfide.
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