|Jmol-3D images||Image 1|
|Molar mass||123.555 g/mol|
|Melting point||200 °C|
|Boiling point||decomposes at 290 °C|
|Solubility in water||insoluble|
|Solubility||soluble in acetic acid|
|Std enthalpy of
|LD50||159 mg/kg (rat, oral)|
|Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)|
|(what is: / ?)|
Copper(II) carbonate (often called copper carbonate or cupric carbonate) is a blue-green compound (chemical formula CuCO3) forming part of the verdigris patina that is found on weathered brass, bronze, and copper. The colour can vary from bright blue to green, because there may be a mixture of both copper carbonate and basic copper carbonate in various stages of hydration. It was formerly much used as a pigment, and is still in use for artist's colours. It has also been used in some types of make-up, like lipstick, although it can also be toxic to humans. It also has been used for many years as an effective algaecide in farm ponds and in aquaculture operations. Copper carbonate was the first compound to be broken down into several, separate elements (copper, carbon, and oxygen). It was broken down in 1794 by the French chemist Joseph Louis Proust (1754–1826). When heated, it thermally decomposes to form CO2 and CuO, cupric oxide, a black solid.
Copper in moist air slowly acquires a dull green coating because its top layer has oxidised with the air. Some architects use this material on rooftops for this interesting colour. The green material is a 1:1 mole mixture of Cu(OH)2 and CuCO3:
- 2 Cu (s) + H2O (g) + CO2 + O2 → Cu(OH)2 + CuCO3 (s)
- CuCO3 (s) → CuO (s) + CO2 (g)
Copper carbonate is prepared by combining aqueous solutions of copper sulfate and sodium carbonate. Copper basic carbonate precipitates from the solution:
- 2 CuSO4 + 2 Na2CO3 + H2O → Cu2(OH)2CO3 + 2 Na2SO4 + CO2
The formation of copper carbonate can be verified in the following steps: a) Centrifuge the above mentioned solution, 1 minute at 6000 g is sufficient b) Wash the precipitate with distilled water and centrifuge again c) The colour of the precipitate is blue, like that of several copper salts but none of the sodium salts d) If dilute (1M) hydrochloric acid is added, then bubbles of CO2 will emerge and the precipitate will be fully solubilised. These would not be formed if dilute hydrochloric acid was added to solid Na2SO4.
Pure copper carbonate is obtained from basic copper carbonate in the presence of carbon dioxide at 180 °C and 4.6 MPa (46 atm) pressure.
- Masterson, W. L., & Hurley, C. N. (2004). Chemistry: Principles and Reactions, 5th Ed. Thomson Learning, Inc. (p 498).
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