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Silver sulfide

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Title: Silver sulfide  
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Silver sulfide

Silver sulfide
Ball-and-stick model of silver sulfide
Sample of silver sulfide
Names
IUPAC name
Silver(I) sulfide, Silver sulfide
Identifiers
 Y
ChemSpider  N
EC number 244-438-2
Jmol-3D images Image
PubChem
UNII  N
Properties
Ag2S
Molar mass 247.80 g·mol−1
Appearance Grayish-black 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 (20 °C)
6.31·10−50
Solubility Soluble in aq. HCN, aq. citric acid with KNO3
Insoluble in acids, alkalies, aqueous ammoniums[4]
Structure
Monoclinic, mP12 (β-form)
Cubic, cI8 (α-form)
Cubic, cF12 (γ-form)[3][5]
P21/n, No. 14 (α-form)[5]
Im3m, No. 229 (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]
−32.59 kJ/mol[6]
−40.71 kJ/mol[6]
Hazards
Main hazards May cause irritation
GHS pictograms The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)[2]
GHS signal word Warning
H315, H319, H335[2]
P261, P305+351+338[2]
Irritant Xi
R-phrases R36/37/38
S-phrases S26, S36
NFPA 704
[7]
0
0
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
 N  (: Y/N?)

Silver sulfide (Ag
2
S
) is the sulfide of silver. It is useful as a photosensitizer in photography.

Contents

  • Properties 1
  • Structure 2
  • References 3
  • External links 4

Properties

This dense black solid constitutes the

Tarnishing of Silver: A Short Review V&A Conservation Journal

External links

  1. ^ a b Lide, David R., ed. (2009).  
  2. ^ a b c d Sigma-Aldrich Co., Silver sulfide. Retrieved on 2014-07-13.
  3. ^ a b c d Tonkov, E. Yu (1992). High Pressure Phase Transformations: A Handbook 1. Gordon and Breach Science Publishers. p. 13.  
  4. ^ Comey, Arthur Messinger; Hahn, Dorothy A. (1921-02). A Dictionary of Chemical Solubilities: Inorganic (2nd ed.). New York: The MacMillan Company. p. 835. 
  5. ^ a b c d e "Silver sulfide (Ag2S) crystal structure" 41C. Springer Berlin Heidelberg. 1998. pp. 1–4.  
  6. ^ a b c d Pradyot, Patnaik (2003). Handbook of Inorganic Chemicals. The McGraw-Hill Companies, Inc. p. 845.  
  7. ^ "MSDS of Silver Sulfide". http://www.saltlakemetals.com. Utah, USA: Salt Lake Metals. Retrieved 2014-07-13. 
  8. ^ "Silver". http://www.chemistryexplained.com. Advameg, Inc. Retrieved 2014-07-13. 
  9. ^  
  10. ^ Zumdahl, Steven S.; DeCoste, Donald J. (2013). Chemical Principles (7th ed.). p. 505.  
  11. ^ FRUEH, A. J. (1958). The crystallography of silver sulfide, Ag2S. Zeitschrift für Kristallographie-Crystalline Materials, 110(1-6), 136-144.

References

Three forms are known: monoclinic acanthite (β-form), stable below 179 °C, body centered cubic so-called argentite (α-form), stable above 180 °C, and a high temperature face-centred cubic (γ-form) stable above 586 °C.[5] The higher temperature forms are electrical conductors. It is found in nature as relatively low temperature mineral acanthite. Acanthite is an important ore of silver. In the acanthite, monoclinic, form there are two crystallographically distinct silver atoms with two and three near neighbour sulfur atoms respectively.[11] 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.

Structure

Degrading wooden treasure chests aboard sunken galleons can provide the sulfide needed for certain sulfide ion consuming bacteria to produce hydrogen sulfide gas. When combined with silver the hydrogen sulfide gas creates a layer of black silver sulfide patina on the silver, protecting the inner silver from further conversion to silver sulfide. [10]

can form. silver whiskers, long filaments known as hydrogen sulfide operating in an atmosphere rich in electrical contacts When formed on [9]

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