When copper carbonate meets water, it immediately double hydrolyzes into a mixture of Basic Copper Carbonateand copper hydroxide. There is no copper carbonate in the aqueous solution. This is also the reason why copper carbonate is "-" in the solubility table of chemistry textbooks.

Copper hydroxide is dissolved in potassium carbonate solution to produce a dark blue complex ion solution. Copper salt solution and excess potassium carbonate generate K2 [Cu (CO3) 2] (dark blue), K2 [Cu (CO3) 2] · 2H2O (bright blue) and K2 [Cu (CO3) 2] · 4H2O (shallow Blue-green) and other complexes.

The basic copper carbonate has a blue or green color depending on the composition (as explained above). It is an amorphous powder with fine particles and a density of 3.85. The degree of hydrolysis is extremely high, it is soluble in acid and forms the corresponding copper salt, and it is soluble in the aqueous solution of cyanide, sodium hydroxide, ammonium salt and carbonate of alkali metal to form a copper complex. When boiled in an alkali metal carbonate solution, brown copper oxide is formed and decomposes into black copper oxide at 200 ° C. It is unstable in a hydrogen sulfide atmosphere. There are more than a dozen compounds in basic copper carbonate according to the ratio of CuCO3: H2O. In industrial production, its molecular formula is CuCO3 · Cu (OH) 2 · xH2O. The solubility in water is 0.0008%, and its decomposition temperature is 200-220 ° C. Low toxicity.

In addition, it should be noted that the reaction between sodium carbonate and copper salt is a mixture of basic copper carbonate and copper hydroxide. The specific composition depends on the reaction conditions, which is caused by the intense hydrolysis of sodium carbonate.