Copper(I) oxide
Copper oxide or cuprous oxide is an oxide of
copper. It is insoluble in water and organic solvents. Copper oxide dissolves in concentrated
ammonia solution to form the colourless complex [Cu2]+, which easily
oxidises in air to the blue [Cu42]2+. It dissolves in
hydrochloric acid to form HCuCl2 , while dilute
sulfuric acid and
nitric acid produce
copper sulfate and
copper nitrate, respectively.
Encyclopedia
| Copper oxide |
|---|
| |
| General |
|---|
| Systematic name | Copper oxide |
| Other names | Cuprous oxide
Cuprite
Red copper oxide |
| Molecular formula | Cu2O |
| Molar mass | 143.09 g/mol |
| Appearance | Brownish-red solid |
| CAS number | [1317-39-1] |
| Properties |
|---|
| Density and phase | 6.0 g/cm3, solid |
| Solubility in water | Insoluble |
Ethanol
Aqueous ammonia | Insoluble
Soluble |
| Melting point | 1235 °C |
| Decomposition to Cu + O2 | 1800 °C |
| Band gap | 2.0 eV |
| Structure |
|---|
| Coordination geometry | ? |
| Crystal structure | cubic |
| Hazards |
|---|
| MSDS | External MSDS |
| Main hazards | ?
|
| R/S statement | R: 22
S: 22 |
| RTECS number | GL8050000 |
| Supplementary data page |
|---|
Structure and
properties | n, er, etc. |
Thermodynamic
data | Phase behaviour
Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds |
|---|
| Other anions | Copper sulfide
Copper sulfide
Copper selenide |
| Other cations | Copper oxide,
Silver oxide,
Nickel oxide,
Zinc oxide |
Except where noted otherwise, data are given for
materials in their standard state
|
|
Copper oxide or
cuprous oxide is an oxide of
copper. It is insoluble in water and organic solvents. Copper oxide dissolves in concentrated
ammonia solution to form the colourless complex
[Cu
2]+, which easily
oxidises in air to the blue
[Cu
42]2+. It dissolves in
hydrochloric acid to form HCuCl
2 , while dilute
sulfuric acid and
nitric acid produce
copper sulfate and
copper nitrate, respectively.
Copper oxide is found as the
mineral cuprite in some red-colored rocks. When it is exposed to oxygen, copper will naturally oxidize to copper oxide, but this takes extensive periods of time. Artificial formation is usually accomplished at high temperature or at high oxygen pressure. With further heating, copper oxide will form copper oxide.
Formation of copper oxide is the basis of the sensitive Fehling's test for
sugars. In the presence of a reducing sugar, an alkaline solution of a copper salt in potassium sodium
tartrate will be reduced and give a precipitate of Cu
2O.
Cuprous oxide forms on
silver-plated copper parts exposed to moisture when the silver layer is porous or damaged; this kind of
corrosion is known as red plague.
Applications as semiconductor
Copper oxide was the first substance known to behave as a
semiconductor.
Rectifier diodes based on this material were used industrially as early as 1924, long before
silicon became the standard.
Copper oxide shows four well understood series of excitons with resonance widths in the range of neV. The associated polaritons are also well understood; their
group velocity turns out to be very low, almost down to the speed of
sound. That means
light moves almost as slow as sound in this medium. This results in high polariton densities, and effects like
Bose-Einstein condensation, the dynamical
Stark effect and phonoritons have been demonstrated.
Another extraordinary feature of the ground state excitons is that all primary scattering mechanisms are known quantitatively. Cu
2O was the first substance where an entirely parameter-free model of absorption linewidth broadening by temperature could be established, allowing the corresponding absorption coefficient to be deduced. It can be shown using Cu
2O that the Kramers-Krönig relations do not apply to polaritons.
See also
References
- N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997.
- Handbook of Chemistry and Physics, 71st edition, CRC Press, Ann Arbor, Michigan, 1990.
- The Merck Index, 7th edition, Merck & Co, Rahway, New Jersey, USA, 1960.
- D. Nicholls, Complexes and First-Row Transition Elements, Macmillan Press, London, 1973.
- P.W. Baumeister: Optical Absorption of Cuprous Oxide, Phys. Rev. 121 , 359.
- L. Brillouin: Wave Propagation and Group Velocity, Academic Press, New York, 1960.
- D. Fröhlich, A. Kulik, B. Uebbing, and A. Mysyrovicz: Coherent Propagation and Quantum Beats of Quadrupole Polaritons in Cu2O, Phys. Rev. Lett. 67 , 2343.
- L. Hanke: Transformation von Licht in Wärme in Kristallen - Lineare Absorption in Cu2O, ISBN 3-8265-7269-6, Shaker, Aachen, 2000; .
- L. Hanke, D. Fröhlich, A.L. Ivanov, P.B. Littlewood, and H. Stolz: LA-Phonoritons in Cu2O, Phys. Rev. Lett. 83 , 4365.
- L. Hanke, D. Fröhlich, and H. Stolz: Direct observation of longitudinal acoustic phonon absorption to the 1S-exciton in Cu2O, Sol. Stat. Comm. 112 , 455.
- J.J. Hopfield, Theory of the Contribution of Excitons to the Complex Dielectric Constant of Crystals, Phys. Rev. 112 , 1555.
- J.P. Wolfe and A. Mysyrowicz: Excitonic Matter, Scientific American is a popular-science [i] magazine [i], published since August 28 [i]...
250 , No. 3, 98. - Knovel Critical Tables., Knovel, 2003.
External links
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