Dicopper sulphide

Endpoint summary

Additional information

The physical and chemical properties of dicopper sulphide are summarised in the following table.

Property	Value	Remarks
Physical state at 20°C and 101.3 kPa	Solid.	Form: Powder. Colour: Bluish black. Odour: Odourless.
Melting/freezing point	1114°C.
Boiling point	Not applicable.	Not required for substances with a melting point greater than 300°C.
Relative density	5.429 g/cm^3at 20°C.
Vapour pressure	Not applicable.	The substance is inorganic in nature and as such has negligible vapour pressure at environmentally relevant temperatures.
Surface tension	72.2 mN/m at 20°C	Concentration tested 0.018 g/l.
Water solubility	<0.01 g/L at 20°C.	pH not stated. Dicopper sulphide is known to be very insoluble in water, and measurement of actual solubility is problematic. Theoretical estimates range from 3.43E^-10µg/L to 1.36E^-08µg/L. Analytical limits of determination for copper in water samples typically range between 0.1 and 10 µg/l, depending on the purity of the water and instrument sensitivity. Given the orders of magnitude difference between the expected solubility and the analytical constraints of methods used in standardised solubility testing, it is not technically feasible to provide more definitive experimental data to support the water solubility of copper sulphide.
Partition coefficient n-octanol/water (log value)	Not applicable.	The octanol:water partition coefficient, Pow, is defined as the ratio of the equilibrium concentrations of a dissolved substance in each of the phases in a two phase system consisting of octanol and water. It is usually expressed on a log scale. It is a key parameter in studies of the environmental fate of organic substances, indicating the potential for bioaccumulation and soil absorption. However, the mechanisms of absorption of Cu^2+into organic matter and living cells are understood to be different from those traditionally attributed to carbon-based substances and the parameter therefore has little relevance to ionic copper. The parameter is therefore not considered to be relevant to dicopper sulphide.
Flash point	Not applicable.	Not required as the substance is solid.
Flammability	Not flammable.	A preliminary screening test failed to ignite the sample. Copper (I) sulphide is therefore not considered to be flammable. Based on experience in use, dicopper sulphide is not pyrophoric (EU Method A.13) and is not flammable in contact with water (EU Method A.12).
Explosive properties	Not explosive.	Copper (I) sulphide was assessed for chemical groups that imply explosive properties. Since none of these are present in the chemical structure of the test substance, copper (I) sulphide is considered not to be explosive. Additionally, DSC data obtained show only a low energy potential with regard to decomposition (maximum decomposition energy of −120.1 J/g). In the case of an explosive substance the exothermic decomposition energy is much higher.
Self-ignition temperature	240.4 °C
Oxidising properties	No oxidising properties.	According to the UN ‘Manual of test & Criteria’, the classification procedure for inorganic substances does not need to be applied if the substance does not contain any oxygen or halogen atoms. Copper (I) sulfide is therefore not considered to possess any oxidising properties.
Granulometry	Five different copper compounds were subjected to total particle size analysis, resulting in d50 values in the range 3.3 - 220.4 µm. The results of this exercise are illustrative of the range of Particle Size Distributions found across whole copper compound industry and are therefore inclusive of copper sulphide from the large majority of sources.
Stability in organic solvents and identity of relevant degradation products	Not applicable.	As stated in the REACH regulations, the study does not need to be conducted if the substance is inorganic.
Dissociation constant	Not applicable.	Due to the low water solubility of copper (I) sulfide (<1x10^-2g/l), it was not possible to determine the dissociation constants in water.
Viscosity	Not applicable.	Not applicable to solids.
Auto flammability	Following a preliminary screening test, it was concluded that copper (I) sulphide is not likely to auto-ignite.