Basic copper carbonate

For the neutral compound, see Copper(II) carbonate.
Basic copper carbonate
Basic copper carbonate

Ball-and-stick model of part of the crystal structure of malachite, highlighting the formula unit
Names
IUPAC name
Dicopper carbonate dihydroxide
Other names
copper carbonate hydroxide, cupric carbonate, copper carbonate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.031.909 Edit this at Wikidata
UNII
  • InChI=1S/CH2O3.2Cu.2H2O/c2-1(3)4;;;;/h(H2,2,3,4);;;2*1H2/q;2*+2;;/p-4
    Key: ZMMDPCMYTCRWFF-UHFFFAOYSA-J
  • InChI=1/CH2O3.2Cu.2H2O/c2-1(3)4;;;;/h(H2,2,3,4);;;2*1H2/q;2*+2;;/p-4
    Key: ZMMDPCMYTCRWFF-XBHQNQODAP
  • C(=O)([O-])[O-].[OH-].[OH-].[Cu+2].[Cu+2]
Properties
Cu2(OH)2CO3
Molar mass 221.114 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
7.08·10−9
Thermochemistry
88 J/mol·K
−595 kJ/mol
Hazards
GHS labelling:
GHS07: Exclamation mark[1]
Warning
H302, H315, H319, H335[1]
P261, P305+P351+P338[1]
Lethal dose or concentration (LD, LC):
159 mg/kg (rat, oral)
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 1 mg/m3 (as Cu)[2]
REL (Recommended)
 TWA 1 mg/m3 (as Cu)[2]
IDLH (Immediate danger)
 TWA 100 mg/m3 (as Cu)[2]
Safety data sheet (SDS) Oxford MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Basic copper carbonate is a chemical compound, more properly called copper(II) carbonate hydroxide. It can be classified as a coordination polymer or a salt. It consists of copper(II) bonded to carbonate and hydroxide with formula Cu2(CO3)(OH)2. It is a green solid that occurs in nature as the mineral malachite. It has been used since antiquity as a pigment, and it is still used as such in artist paints, sometimes called verditer, green bice, or mountain green.[3]

Sometimes basic copper carbonate refers to Cu
3(CO
3)2(OH)2, a blue crystalline solid also known as the mineral azurite. It too has been used as pigment, sometimes under the name mountain blue or blue verditer.

Both 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.[4]

This compound is often improperly called (even in chemistry articles) copper carbonate, cupric carbonate, and similar names. The true (neutral) copper(II) carbonate CuCO3 is not known to occur naturally.[5] It is decomposed by water or moisture from the air. It was synthesized only in 1973 by high temperature and very high pressures.[6]

Preparation

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

Basic copper carbonate is prepared by combining aqueous solutions of copper(II) sulfate and sodium carbonate. Basic copper carbonate precipitates from the solution, with release of carbon dioxide CO
2:[7]

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

Basic copper carbonate can also be prepared by treating aqueous solutions of copper(II) sulfate with sodium bicarbonate.

Copper(II) sulfate may also be substituted with Copper(II) chloride.

Reactions

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Basic copper carbonate is decomposed by acids, such as solutions of hydrochloric acid HCl, into the copper(II) salt and carbon dioxide.

In 1794 the French chemist Joseph Louis Proust (1754–1826) thermally decomposed copper carbonate to CO2 and CuO, cupric oxide.[8]

The basic copper carbonates, malachite and azurite, both decompose forming H2O, CO2, and CuO, cupric oxide.[9]

Uses

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Basic copper carbonate is used to remove thiols and hydrogen sulfide from some gas streams, a process called "sweetening". Like many other copper compounds, it also has been used as an algaecide, wood preservative and similar applications. It is a precursor to various catalysts and copper soaps.[3]

Both malachite and azurite, as well as synthetic basic copper carbonate have been used as pigments.[10] One example of the use of both azurite and its artificial form blue verditer[11] is the portrait of the family of Balthasar Gerbier by Peter Paul Rubens.[12] The green skirt of Deborah Kip is painted in azurite, smalt, blue verditer (artificial form of azurite), yellow ochre, lead-tin-yellow and yellow lake. The green color is achieved by mixing blue and yellow pigments.[13]

References

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  1. ^ a b c Copper(II) carbonate basic
  2. ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0150". National Institute for Occupational Safety and Health (NIOSH).
  3. ^ a b Zhang, Jun; Richardson, H. Wayne (2016). "Copper Compounds". Ullmann's Encyclopedia of Industrial Chemistry. pp. 1–31. doi:10.1002/14356007.a07_567.pub2. ISBN 978-3-527-30673-2.
  4. ^ Encyclopedia Of Corrosion Technology (Google eBook), Philip A. Schweitzer P.E.; CRC Press, 2004, ISBN 08247-4878-6
  5. ^ Holleman, Arnold Frederik; Wiberg, Egon (2001), Wiberg, Nils (ed.), Inorganic Chemistry, translated by Eagleson, Mary; Brewer, William, San Diego/Berlin: Academic Press/De Gruyter, p. 1263, ISBN 0-12-352651-5
  6. ^ Seidel, H.; Ehrhardt, H.; Viswanathan, K.; Johannes, W. (1974). "Darstellung, Struktur und Eigenschaften von Kupfer(II)-Carbonat". Zeitschrift für anorganische und allgemeine Chemie. 410 (2): 138–148. doi:10.1002/zaac.19744100207. ISSN 0044-2313.
  7. ^ Jack Reginald Irons Hepburn (1927): "The chemical nature of precipitated basic cupric carbonate". Article CCCLXXXVI, Journal of the Chemical Society (Resumed), volume 1927, pp. 2883–2896. doi:10.1039/JR9270002883
  8. ^ Kapoor, Satish C. (1965). "Berthollet, Proust, and Proportions". Chymia. 10: 53–110. doi:10.2307/27757247. ISSN 0095-9367.
  9. ^ Brown, I.W.M.; Mackenzie, K.J.D.; Gainsford, G.J. (1984). "Thermal decomposition of the basic copper carbonates malachite and azurite". Thermochimica Acta. 75 (1–2): 23–32. doi:10.1016/0040-6031(84)85003-0. ISSN 0040-6031.
  10. ^ Valentine Walsh, Tracey Chaplin, Pigment Compendium: A Dictionary and Optical Microscopy of Historical Pigments, 2008, Routledge, ISBN 978-0-7506-8980-9
  11. ^ Blue verditer, ColourLex
  12. ^ Robert L. Feller, Rubens’s: The Gerbier Family: Technical Examination of the Pigments and Paint Layers, Studies in the History of Art, Vol. 5 (1973), pp. 54–74.
  13. ^ Peter Paul Rubens, The Gerbier Family, ColourLex
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