This compound is rarely encountered because it is difficult to prepare[2] and readily reacts with water moisture from the air. The terms "copper carbonate", "copper(II) carbonate", and "cupric carbonate" almost always refer (even in chemistry texts) to a basic copper carbonate (or copper(II) carbonate hydroxide), such as Cu 2(OH)2CO 3 (which occurs naturally as the mineral malachite) or Cu 3(OH)2(CO 3)2 (azurite). For this reason, the qualifier neutral may be used instead of "basic" to refer specifically to CuCO 3.
Reactions that may be expected to yield CuCO 3, such as mixing solutions of copper(II) sulfateCuSO 4 and sodium carbonateNa 2CO 3 in ambient conditions, yield instead a basic carbonate and CO 2, due to the great affinity of the Cu2+ ion for the hydroxide anion HO− .[5]
Thermal decomposition of the basic carbonate at atmospheric pressure yields copper(II) oxideCuO rather than the carbonate.
In 1960, C. W. F. T. Pistorius claimed synthesis by heating basic copper carbonate at 180 °C in an atmosphere of carbon dioxideCO 2 (450 atm) and water (50 atm) for 36 hours. The bulk of the products was well-crystallized malachite Cu 2CO 3(OH)2, but a small yield of a rhombohedral substance was also obtained, claimed to be CuCO 3.[6] However, this synthesis was apparently not reproduced.[2]
Reliable synthesis of true copper(II) carbonate was reported for the first time in 1973 by Hartmut Ehrhardt and others. The compound was obtained as a gray powder, by heating basic copper carbonate in an atmosphere of carbon dioxide (produced by the decomposition of silver oxalateAg 2C 2O 4) at 500 °C and 2 GPa (20,000 atm). The compound was determined to have a monoclinic structure.[7]
Chemical and physical propertiesedit
The stability of dry CuCO 3 depends critically on the partial pressure of carbon dioxide (pCO2). It is stable for months in dry air, but decomposes slowly into CuO and CO 2 if pCO2 is less than 0.11 atm.[3]
In the presence of water or moist air at 25 °C, CuCO 3 is stable only for pCO2 above 4.57 atmospheres and pH between about 4 and 8.[8] Below that partial pressure, it reacts with water to form a basic carbonate (azurite, Cu 3(CO 3)2(OH)2).[3]
3 CuCO 3 + H 2O → Cu 3(CO 3) 2(OH) 2 + CO 2
In highly basic solutions, the complex anion Cu(CO 3)2− 2 is formed instead.[3]
The solubility product of the true copper(II) carbonate was measured by Reiterer and others as pKso = 11.45 ± 0.10 at 25 °C.[2][3][4]
^ abcdH. Seidel, H. Ehrhardt, K. Viswanathan, W. Johannes (1974): "Darstellung, Struktur und Eigenschaften von Kupfer(II)-Carbonat". Z. anorg. allg. Chem., volume 410, pages 138-148. doi:10.1002/zaac.19744100207
^ abcdRolf Grauer (1999) "Solubility Products of M(II) Carbonates". Technical Report NTB-99-03, NAGRA - National Cooperative for the Disposal of Radioactive Waste; pages 8, 14, and 17. Translated by U. Berner.
^ abcdeF. Reiterer, W. Johannes, H. Gamsjäger (1981): "Semimicro Determination of Solubility Constants: Copper(II) Carbonate and Iron(II) Carbonate". Mikrochim. Acta, volume 1981, page 63. doi:10.1007/BF01198705
^Ahmad, Zaki (2006). Principles of Corrosion Engineering and Corrosion Control. Oxford: Butterworth-Heinemann. pp. 120–270. ISBN9780750659246.
^C. W. F. T. Pistorius (1960): "Synthesis at High Pressure and Lattice Constants of Normal Cupric Carbonate". Experientia, volume XVI, page 447-448. doi:10.1007/BF02171142
^Hartmut Erhardt, Wilhelm Johannes, and Hinrich Seidel (1973): "Hochdrucksynthese von Kupfer(II)-Carbonat", Z. Naturforsch., volume 28b, issue 9-10, page 682. doi:10.1515/znb-1973-9-1021
^H. Gamsjäger and W. Preis (1999): "Copper Content in Synthetic Copper Carbonate." Letter to J. Chem. Educ., volume 76, issue 10, page 1339. doi:10.1021/ed076p1339.1
November 17, 2023
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This article is about the rare neutral carbonate For the copper carbonate of commerce see basic copper carbonate Copper II carbonate or cupric carbonate is a chemical compound with formula CuCO3 At ambient temperatures it is an ionic solid a salt consisting of copper II cations Cu2 and carbonate anions CO2 3 Copper II carbonate NamesIUPAC name Copper II carbonateOther names Cupric carbonate neutral copper carbonateIdentifiersCAS Number 1184 64 1 Y ECHA 3D model JSmol Interactive imageChemSpider 13799ECHA InfoCard 100 013 338EC Number 214 671 4PubChem CID 14452UNII 9AOA5F11GJ YCompTox Dashboard EPA DTXSID6034471InChI InChI 1S CH2O3 Cu c2 1 3 4 h H2 2 3 4 q 2 p 2Key GEZOTWYUIKXWOA UHFFFAOYSA LSMILES C O O O Cu 2 PropertiesChemical formula CuCO3Molar mass 123 5549Appearance gray powder 1 Solubility in water reacts with water at normal conditions clarification needed Solubility product Ksp 10 11 45 0 10 at 25 C 2 3 4 StructureSpace group Pa C2s 7 1 Lattice constant a 6 092 A b 4 493 A c 7 030 Aa 90 b 101 34 g 90 Coordination geometry 5 1 HazardsFlash point Non flammableRelated compoundsOther anions Copper II sulfateOther cations Nickel II carbonateZinc carbonateExcept where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa N what is Y N Infobox references This compound is rarely encountered because it is difficult to prepare 2 and readily reacts with water moisture from the air The terms copper carbonate copper II carbonate and cupric carbonate almost always refer even in chemistry texts to a basic copper carbonate or copper II carbonate hydroxide such as Cu2 OH 2CO3 which occurs naturally as the mineral malachite or Cu3 OH 2 CO3 2 azurite For this reason the qualifier neutral may be used instead of basic to refer specifically to CuCO3 Contents 1 Preparation 2 Chemical and physical properties 3 Structure 4 ReferencesPreparation editReactions that may be expected to yield CuCO3 such as mixing solutions of copper II sulfate CuSO4 and sodium carbonate Na2 CO3 in ambient conditions yield instead a basic carbonate and CO2 due to the great affinity of the Cu2 ion for the hydroxide anion HO 5 Thermal decomposition of the basic carbonate at atmospheric pressure yields copper II oxide CuO rather than the carbonate In 1960 C W F T Pistorius claimed synthesis by heating basic copper carbonate at 180 C in an atmosphere of carbon dioxide CO2 450 atm and water 50 atm for 36 hours The bulk of the products was well crystallized malachite Cu2 CO3 OH 2 but a small yield of a rhombohedral substance was also obtained claimed to be CuCO3 6 However this synthesis was apparently not reproduced 2 Reliable synthesis of true copper II carbonate was reported for the first time in 1973 by Hartmut Ehrhardt and others The compound was obtained as a gray powder by heating basic copper carbonate in an atmosphere of carbon dioxide produced by the decomposition of silver oxalate Ag2 C2 O4 at 500 C and 2 GPa 20 000 atm The compound was determined to have a monoclinic structure 7 Chemical and physical properties editThe stability of dry CuCO3 depends critically on the partial pressure of carbon dioxide pCO2 It is stable for months in dry air but decomposes slowly into CuO and CO2 if pCO2 is less than 0 11 atm 3 In the presence of water or moist air at 25 C CuCO3 is stable only for pCO2 above 4 57 atmospheres and pH between about 4 and 8 8 Below that partial pressure it reacts with water to form a basic carbonate azurite Cu3 CO3 2 OH 2 3 3 CuCO3 H2 O Cu3 CO3 2 OH 2 CO2In highly basic solutions the complex anion Cu CO3 2 2 is formed instead 3 The solubility product of the true copper II carbonate was measured by Reiterer and others as pKso 11 45 0 10 at 25 C 2 3 4 Structure editIn the crystal structure of CuCO3 copper adopts a distorted square pyramidal coordination environment with coordination number 5 Each carbonate ion bonds to 5 copper centres 1 nbsp Unit cell of CuCO3 nbsp Copper coordination environment nbsp Carbonate coordination environmentReferences edit a b c d H Seidel H Ehrhardt K Viswanathan W Johannes 1974 Darstellung Struktur und Eigenschaften von Kupfer II Carbonat Z anorg allg Chem volume 410 pages 138 148 doi 10 1002 zaac 19744100207 a b c d Rolf Grauer 1999 Solubility Products of M II Carbonates Technical Report NTB 99 03 NAGRA National Cooperative for the Disposal of Radioactive Waste pages 8 14 and 17 Translated by U Berner a b c d e F Reiterer W Johannes H Gamsjager 1981 Semimicro Determination of Solubility Constants Copper II Carbonate and Iron II Carbonate Mikrochim Acta volume 1981 page 63 doi 10 1007 BF01198705 a b F Reiterer 1980 Loslichkeitskonstanten und Freie Bildungsenthalpien neutraler Ubergangsmetallcarbonate Thesis Montanuniversitat Leoben Ahmad Zaki 2006 Principles of Corrosion Engineering and Corrosion Control Oxford Butterworth Heinemann pp 120 270 ISBN 9780750659246 C W F T Pistorius 1960 Synthesis at High Pressure and Lattice Constants of Normal Cupric Carbonate Experientia volume XVI page 447 448 doi 10 1007 BF02171142 Hartmut Erhardt Wilhelm Johannes and Hinrich Seidel 1973 Hochdrucksynthese von Kupfer II Carbonat Z Naturforsch volume 28b issue 9 10 page 682 doi 10 1515 znb 1973 9 1021 H Gamsjager and W Preis 1999 Copper Content in Synthetic Copper Carbonate Letter to J Chem Educ volume 76 issue 10 page 1339 doi 10 1021 ed076p1339 1 Retrieved from https en wikipedia org w index php title Copper II carbonate amp oldid 1155687331, wikipedia, wiki, book, books, library,
