Basic copper carbonate

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Basic copper carbonate
Basic copper carbonate
Names
IUPAC name
Dicopper carbonate dihydroxide
Other names
copper carbonate hydroxide, cupric carbonate, copper carbonate
Identifiers
12069-69-1 N
Properties
Cu2(OH)2CO3
Molar mass 221.116 g/mol
Appearance green powder
Density 4 g/cm3
Melting point 200 °C (392 °F; 473 K)
Boiling point 290 °C (554 °F; 563 K) decomposes
insoluble
7.08·109
Thermochemistry
88 J/mol·K
−595 kJ/mol
Vapor pressure {{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Basic copper carbonate normally refers to the compound (Cu2(OH)2CO3) (the mineral malachite). Sometimes the name is used for Cu3(OH)2(CO3)2 (the related mineral azurite). Malachite and azurite can be found in the verdigris patina that is found on weathered brass, bronze, and copper. The composition of the patina can vary, in a maritime environment depending on the environment a basic chloride may be present, in an urban environment basic sulfates may be present.[1]

The compound Copper(II) carbonate CuCO3 is not known to occur naturally.[2] There is a report from 1973 of the production of CuCO3 from CuO or Cu3(CO3)2(OH)2 in the presence of carbon dioxide at 500 °C and 20 kb (2 GPa) pressure.[3] What is often called copper(II) carbonate or cupric carbonate is actually basic copper carbonate.

Preparation

Basic copper carbonate is prepared by combining aqueous solutions of copper(II) sulfate and sodium carbonate. Basic copper carbonate precipitates from the solution:

2 CuSO4 + 2 Na2CO3 + H2O → Cu2(OH)2CO3 + 2 Na2SO4 + CO2

The formation of basic copper carbonate can be verified in the following steps: a) Centrifuge (or filter) the above-mentioned solution; 1 minute at 6000 g is sufficient b) Wash the precipitate with distilled water and centrifuge or filter 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.

Basic copper(II) carbonate patina on roofs of Château Frontenac.

Reactions

"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. The basic copper carbonates, malachite and azurite, both decompose forming CO2 and CuO, cupric oxide.[4]


Uses

Both malachite and azurite basic copper carbonates have been used as pigments.[5] 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.[citation needed]

References

  1. ↑ Encyclopedia Of Corrosion Technology (Google eBook), Philip A. Schweitzer P.E.; CRC Press, 2004, ISBN 08247-4878-6
  2. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ Valentine Walsh, Tracey Chaplin, Pigment Compendium: A Dictionary and Optical Microscopy of Historical Pigments, 2008, Routledge, ISBN 978-0-7506-8980-9

External links

Carbonates
H2CO3 He
Li2CO3 BeCO3 B C (NH4)2CO3,
NH4HCO3		 O F Ne
Na2CO3,
NaHCO3,
Na3H(CO3)2		 MgCO3,
Mg(HCO3)2		 Al2(CO3)3 Si P S Cl Ar
K2CO3,
KHCO3		 CaCO3,
Ca(HCO3)2		 Sc Ti V Cr MnCO3 FeCO3 CoCO3 NiCO3 CuCO3 ZnCO3 Ga Ge As Se Br Kr
Rb2CO3 SrCO3 Y Zr Nb Mo Tc Ru Rh Pd Ag2CO3 CdCO3 In Sn Sb Te I Xe
Cs2CO3,
CsHCO3		 BaCO3   Hf Ta W Re Os Ir Pt Au Hg Tl2CO3 PbCO3 (BiO)2CO3 Po At Rn
Fr Ra   Rf Db Sg Bh Hs Mt Ds Rg Cn Uut Fl Uup Lv Uus Uuo
↓
La2(CO3)3 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Ac Th Pa UO2CO3 Np Pu Am Cm Bk Cf Es Fm Md No Lr
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