Copper carbonate when heated

Basic copper carbonate

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Basic copper carbonate is a copper salt of carbonic acid. The pure copper (II) carbonate compound (CuCO3) could not be displayed yet. All previously known carbonate compounds of copper (II) are basic compounds such as, for example, those below Occurrence listed copper minerals. Metallic copper surfaces first become copper (I) oxide (Cu2O) oxidized and then with further oxidation of the CO2 in the air to green basic copper (II) carbonate, the patina. The latter, however, is rarely a pure basic carbonate and often contains other anions such as sulfate and / or chloride.

Occurrence

Naturally occurring minerals of basic copper (II) carbonates are malachite (CuCO3Cu (OH)2) and azurite (also called copper glaze) (2 CuCO3Cu (OH)2)[5].

Extraction and presentation

If a copper (II) salt solution is mixed with an alkali metal carbonate solution in the laboratory, either a blue or a green precipitate of basic copper (II) carbonate forms, depending on the excess of sodium carbonate. Both basic copper (II) carbonates are insoluble in water and are precipitated and can be filtered off.

The deep blue carbonate is the pigment 2 CuCO3 Cu (OH)2which occurs naturally as azurite mineral. The production of this pigment is described in Gmelin.[6] The equation for this reaction is:

$ \ mathrm {3 \ Na_2 CO_3 + 3 \ CuSO_4 + H_2 O \ longrightarrow} $
$ \ mathrm {3 \ Na_2 SO_4 + 2 \ CuCO_3 \ cdot Cu (OH) _2 \ downarrow + CO_2 \ uparrow} $

Under the influence of light, the deep blue carbonate slowly disintegrates into green malachite (CuCO3 Cu (OH)2). The green precipitate is a more basic pigment with the formula CuCO3Cu (OH)2, the aforementioned green malachite. The equation for this reaction is as follows:

$ \ mathrm {2 \ CuSO_4 + 3 \ Na_2CO_3 +2 \ H_2O \ longrightarrow} $$ \ mathrm {{{CuCO_3} \ cdot \ mathrm {Cu (OH) _2} \ downarrow} + 2 \ Na_2SO_4 +2 \ NaHCO_3} $

properties

Anhydrous copper (II) carbonate is an odorless light blue powder, the monohydrate is dark green. It is insoluble in water and decomposes from 140 ° C to copper (II) oxide and carbon dioxide:

$ \ mathrm {CuCO_3 \ cdot Cu (OH) _2 \ longrightarrow 2 \ CuO + CO_2 + H_2O} $

The reaction with acids produces carbon dioxide and the copper salt of the acid:

$ \ mathrm {CuCO_3 \ cdot Cu (OH) _2 + 4 \ HCl \ longrightarrow} $
$ \ mathrm {2 \ CuCl_2 + CO_2 \ uparrow + \ 3 \ H_2O} $

use

Copper (II) carbonate is used in the production of many copper compounds, such as copper sulfate, CuSO4 and copper (II) oxide, CuO, used.

Individual evidence

  1. 1,01,1data sheet Basic copper carbonate at Merck, accessed January 18, 2011.
  2. 2,02,12,22,32,4Entry to CAS no. 12069-69-1 in the GESTIS substance database of the IFA, accessed on December 9, 2007 (JavaScript required)
  3. 3,03,1data sheet Basic copper carbonate from Sigma-Aldrich, accessed March 9, 2011.
  4. ↑ Since December 1, 2012, only GHS hazardous substance labeling has been permitted for substances. The R-phrases of this substance may still be used to classify preparations until June 1, 2015, after which the EU hazardous substance labeling is of purely historical interest.
  5. Holleman-Wiberg, 37th-39th edition, Verlag Walter de Gruyter, 1956, p.450
  6. ^ Gmelin Institute for Inorganic Chemistry and Frontier Areas in the Max Planck Society. Gmelin's Handbook of Inorganic Chemistry, System Number 60: Copper, Part B, Delivery 2. Weinheim / Bergstrasse, 8th Edition, 1961. S.652.