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Copper(I) sulfide

Chemical compound From Wikipedia, the free encyclopedia

Copper(I) sulfide is a copper sulfide, a chemical compound of copper and sulfur. It has the chemical formula of Cu2S. It is found in nature as the mineral chalcocite. It has a narrow range of stoichiometry ranging from Cu1.997S to Cu2.000S.[6] Samples are typically black.

Quick facts Names, Identifiers ...
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 Edit this at Wikidata
RTECS number
  • GL8910000
UNII
  • InChI=1S/2Cu.S/q2*+1;-2 checkY
    Key: AQMRBJNRFUQADD-UHFFFAOYSA-N checkY
  • InChI=1/2Cu.S/q2*+1;-2
    Key: AQMRBJNRFUQADD-UHFFFAOYAN
  • [Cu+].[Cu+].[S-2]
Properties
Cu2S
Molar mass 159.15 g·mol−1
Appearance blue to grayish black lustrous solid[1]
Density 5.6 g/cm3[1]
Melting point 1,130 °C (2,070 °F; 1,400 K)[2]
insoluble[1]
Solubility insoluble in acetic acid[1]
decomposes in nitric acid and sulfuric acid[1]
slightly soluble in hydrochloric acid[1]
Hazards[3]
NFPA 704 (fire diamond)
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
Flash point Nonflammable
NIOSH (US health exposure limits):[4]
PEL (Permissible)
 TWA 1 mg/m3 (as Cu)
REL (Recommended)
 TWA 1 mg/m3 (as Cu)
IDLH (Immediate danger)
 TWA 100 mg/m3 (as Cu)
Safety data sheet (SDS) Sigma-Aldrich[5]
Related compounds
Other anions
Other cations
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Structure

Crystals of chalcocite (mineral form of Cu2S).

Stoichiometric

Two forms (a dimorphism) of Cu2S are known. The so-called low temperature monoclinic form ("low-chalcocite") has a complex structure with 96 copper atoms in the unit cell.[7] The hexagonal form, stable above 104 °C (219 °F),[8][page needed] has 24 crystallographically distinct Cu atoms. Its 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.

Non-stoichiometric

As illustrated by the mineral djurleite, other cuprous sulfides are known. With the approximate formula Cu1.96S, this material 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]

Phase transition

The electrical resistivity increases abruptly at the phase transition point around 104 °C (219 °F), with the precise temperature depending on the stoichiometry.[10][11]

Preparation

Cu2S can be prepared by treating copper with sulfur or H2S.[2] The rate depends on the particle size and temperature.[12] Cu2S reacts with oxygen to form SO2:[13][page needed]

2 Cu2S + 3 O2 → 2 Cu2O + 2 SO2

Reactions

The production of copper from chalcocite is a typical process in extracting the metal from ores. Usually, the conversion involves roasting, to give Cu2O as an intermediate which is further reduced to the metal, and sulfur dioxide:[13][page needed]

Cu2S + O2 → 2 Cu + SO2

Copper(I) oxide readily converts to copper(II) oxide when heated in the presence of oxygen, and to copper metal upon heating in a reducing environment. (cf. Carbothermic reduction)

See also

References

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