Copper(I) sulfide

Copper(I) sulfide is a copper sulfide, a chemical compound of copper and sulfur. It has the chemical compound Cu2S. It is found in nature as the mineral chalcocite. It has a narrow range of stoichiometry ranging from Cu1.997S to Cu2.000S.[4]

Copper(I) sulfide
Names
IUPAC name
Copper(I) sulfide
Other names
Cuprous sulfide
Chalcocite
Copper glance
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.040.751
RTECS number
  • GL8910000
UNII
Properties
Cu2S
Molar mass 159.16 g/mol
Density 5.6 g/cm3 [1]
Melting point 1,130 °C (2,070 °F; 1,400 K)[2]
Insoluble
Solubility slightly soluble in HCl; soluble in NH4OH; dissolves in KCN; decomposes in HNO3, H2SO4
Hazards
Flash point Non-flammable
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 1 mg/m3 (as Cu)[3]
REL (Recommended)
 TWA 1 mg/m3 (as Cu)[3]
IDLH (Immediate danger)
 TWA 100 mg/m3 (as Cu)[3]
Related compounds
Other anions
 Copper(I) oxide
Copper(I) selenide
Other cations
 Nickel(II) sulfide
Copper(II) sulfide
Zinc sulfide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Preparation and reactions

Cu2S can be prepared by heating copper strongly in sulfur vapour or H2S.[2] The reaction of copper powder in molten sulfur rapidly produces Cu2S, whereas pellets of copper require much higher temperature.[5] Cu2S reacts with oxygen to form SO2:[6]

2 Cu2S + 3 O2 → 2 Cu2O + 2 SO2

In the production of copper two thirds of the molten copper sulfide is oxidised as above, and the Cu2O reacts with unoxidised Cu2S to give Cu metal:[6]

Cu2S + 2 Cu2O → 6 Cu + SO2

Structure

There are two forms of Cu2S: a low temperature monoclinic form ("low-chalcocite") which has a complex structure with 96 copper atoms in the unit cell[7] and a hexagonal form stable above 104 °C.[8] In this structure there are 24 crystallographically distinct Cu atoms and the structure has been described as approximating to a hexagonal close packed array of sulfur atoms with Cu atoms in planar 3 coordination. This structure was initially assigned an orthorhombic cell due to the twinning of the sample crystal.

There is also a crystallographically-distinct phase (the mineral djurleite) with stoichiometry Cu1.96S which is non-stoichiometric (range Cu1.934S-Cu1.965S) and has a monoclinic structure with 248 copper and 128 sulfur atoms in the unit cell.[7] Cu2S and Cu1.96S are similar in appearance and hard to distinguish one from another.[9]

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See also

References
  1. Patnaik, Pradyot (2002). Handbook of Inorganic Chemicals. McGraw-Hill, ISBN 0-07-049439-8
  2. Greenwood, Norman N.; Earnshaw, Alan (1984). Chemistry of the Elements. Oxford: Pergamon Press. p. 1373. ISBN 978-0-08-022057-4.
  3. NIOSH Pocket Guide to Chemical Hazards. "#0150". National Institute for Occupational Safety and Health (NIOSH).
  4. Potter, R. W. (1977). "An electrochemical investigation of the system copper-sulfur". Economic Geology. 72 (8): 1524–1542. doi:10.2113/gsecongeo.72.8.1524.
  5. Blachnik R., Müller A. (2000). "The formation of Cu2S from the elements I. Copper used in form of powders". Thermochimica Acta. 361: 31. doi:10.1016/S0040-6031(00)00545-1.
  6. Wiberg, Egon and Holleman, Arnold Frederick (2001) Inorganic Chemistry, Elsevier ISBN 0-12-352651-5
  7. Evans, H. T. (1979). "Djurleite (Cu1.94S) and Low Chalcocite (Cu2S): New Crystal Structure Studies". Science. 203 (4378): 356–8. doi:10.1126/science.203.4378.356. PMID 17772445.
  8. Wells A.F. (1984) Structural Inorganic Chemistry, 5th ed., Oxford Science Publications, ISBN 0-19-855370-6
  9. Evans H.T. (1981). "Copper coordination in low chalcocite and djurleite and other copper-rich sulfides" (PDF). American Mineralogist. 66 (7–8): 807–818.
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