Copper(II) carbonate

• Patina
• Copper hydroxide

Green solid

Fixed

4.0 g · cm -3

Decomposes on heating

0.8 mg · l-1 in water (20 ° )

Attention

0.1 mg · m-3

1350 mg · kg -1 ( LD50, rat, oral)

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Basic copper is a copper salt of carbonic acid. The pure copper (II ) carbonate compound ( CuCO3 ) could not be shown. All the known carbonate of copper (II), basic compounds such as the below -mentioned occurrence of copper minerals. Metallic copper surfaces are oxidized in the first atmosphere to copper (I ) oxide ( Cu2O ), and then to green basic copper (II) carbonate, the patina is converted by the CO2 of the air to further oxidation. The latter, however, is rarely pure basic carbonate, often containing other anions such as sulphate and / or chloride.

Occurrence

Naturally occurring minerals basic copper (II ) carbonates are malachite ( CuCO3 · Cu ( OH ) 2) and azurite (also called azurite ) (2 CuCO3 · Cu ( OH) 2).

Production and representation

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

In the deep blue carbonate is the pigment CuCO3 2 · Cu ( OH) 2, which occurs as Azuritmineral in nature. The preparation of this pigment is described in Gmelin. The equation for this reaction is:

When exposed to light the deep blue carbonate slowly decomposes to malachite green ( CuCO3 · Cu ( OH) 2). The green precipitate is a more basic pigment with the formula CuCO3 · Cu ( OH) 2, the above angeführtem green malachite. The equation for this reaction is as follows:

Properties

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

In the reaction with acids releasing carbon dioxide and the copper salt of the acid:

Use

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