Copper oxide (I)

Copper oxide (I). Chemical compound formed by the elements copper and oxygen .


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  • 1 Features
  • 2 Information, characteristics and properties
  • 3 Applications
    • 1 General
    • 2 Semiconductor
  • 4 External links


Copper oxide (I) or cuprous oxide (Cu2O) is a chemical compound of colored red or yellow depending on the size of its particles . It is insoluble in water and organic solvents . Copper (I) oxide dissolves in a concentrated ammonia solution to form the colorless complex [Cu (NH3) 2] +, which is easily oxidized in air to the blue complex [Cu (NH3) 4 (H2O) 2] 2+. It dissolves in hydrochloric acid to form HCuCl2 (a CuCl complex), while dissolved with sulfuric acid and nitric acid it producesCopper sulfate (II) and copper nitrate II , respectively.

It is found as the mineral cuprite in some red rocks . When exposed to oxygen , copper naturally oxidizes to copper (I) oxide, albeit very slowly. In the laboratory , the process can be accomplished in a time much shorter using high temperature or high pressure oxygen. With heating , it will form copper (II) oxide.

The formation of copper (I) oxide is the basis of the Fehling test and the Benedict’s Reaction for the reduction of sugars that reduce a copper (II) salt in alkaline solution , giving a Cu2O precipitate.

Cuprous oxide forms in silver- plated copper pieces exposed to moisture when the silver layer is porous or damaged, this type of corrosion is known as a red pest (corrosion).

Information, characteristics and properties

Systematic Name Copper oxide (I)
Other names Cuprous oxide

Cuprite ( Mineral )

Red copper oxide

Molecular formula Cu2O
Molar mass 143.09 g / mol
Appearance Solid brown color
Density and condition 6.0 g / cm3 Solid
Solubility in water and ethanol Insoluble
Melting point 1235 C, 1508 K, 2255F
Boiling point 1800 C, 2073 K, 3272 F



Cuprous oxide is normally used as a pigment , fungicide , among other applications.


It was the first known substance to behave like a semiconductor . The diode rectifiers based on this industrially used already in 1924 , long before the silicon became the standard.

Copper (I) oxide shows four well-known series of excitons with resonance widths in the neV range (10-9 eV). Associated polaritons are also well known; their group speed turns out to be very low, almost lower than the speed of sound . That means that light moves almost as slowly as sound in this medium. This results in a high density of polaritons, and effects such as Bose-Einstein condensation , dynamic Stark effect and noritons have been shown]].

Another extraordinary characteristic of excitons in the ground state is that all the mechanisms of primary dispersion are quantitatively known. Cu2O was the first substance where a totally free parameter model of the absorption line width could be established by the temperature expansion , allowing the corresponding absorption coefficient to be deduced.


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