Copper(I) sulfide

Copper(I) sulfide
IUPAC name Copper(I) sulfide
Other names Cuprous sulfide Chalcocite Copper glance
Identifiers
CAS number	22205-45-4 Y
PubChem	62755
ChemSpider	8305611 Y
ChEBI	CHEBI:51114 Y
RTECS number	GL8910000
Jmol-3D images	Image 1
SMILES [Cu+].[Cu+].[S-2]
InChI InChI=1S/2Cu.S/q2*+1;-2 Y Key: AQMRBJNRFUQADD-UHFFFAOYSA-N Y InChI=1/2Cu.S/q2*+1;-2 Key: AQMRBJNRFUQADD-UHFFFAOYAN
Properties
Molecular formula	Cu2S
Molar mass	159.16 g/mol
Density	5.6 g/cm3 [1]
Melting point	1130 °C[2]
Solubility in water	Insoluble
Solubility	slightly soluble in HCl; soluble in NH4OH; dissolves in KCN; decomposes in HNO3, H2SO4
Hazards
EU Index	Not listed
Flash point	Non-flammable
Related compounds
Other anions	Copper(I) oxide Copper(I) selenide
Other cations	Nickel(II) sulfide Copper(II) sulfide Zinc sulfide
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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 Cu_1.997S to Cu_2.000S^[3].

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^[4] Cu₂S reacts with oxygen to form SO₂:^[5]

2Cu₂S + 3O₂ → 2Cu₂O + 2SO₂

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:^[5]

Cu₂S + 2Cu₂O → 6Cu + 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^[6] and a hexagonal form stable above 104°C.^[7] 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 Cu_1.96S which is non-stoichiometric (range Cu_1.934S-Cu_1.965S) and has a monoclinic structure with 248 copper and 128 sulfur atoms in the unit cell ^[6]. Cu₂S and Cu_1.96S are similar in appearance and hard to distinguish one from another.^[8]

See also

• copper sulfide for an overview of all copper sulfide phases
• copper monosulfide, CuS
• Chalcocite
• Djurleite

References

1. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0070494398
2. ^ ^{a b} Greenwood, Norman N.; Earnshaw, A. (1984). Chemistry of the Elements. Oxford: Pergamon. p. 1373. ISBN 0-08-022057-6. 
3. ^ An electrochemical investigation of the system copper-sulfur, R. W. Potter, Economic Geology; 1977; 72;. 8; 1524-1542
4. ^ The formation of Cu2S from the elements I. Copper used in form of powders, Blachnik R., Müller A., Thermochimica Acta, 361, 1-2, (2000), 31-52, doi:10.1016/S0040-6031(00)00545-1
5. ^ ^{a b} Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN 0123526515
6. ^ ^{a b} H. T. Evans "Djurleite (Cu1.94S) and Low Chalcocite (Cu2S): New Crystal Structure Studies" Science 203 (1979) 356
7. ^ Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
8. ^ Copper coordination in low chalcocite and djurleite and other copper-rich sulfides, Evans H.T., American Mineralogist; August 1981, 66, 7-8, 807-818