Copper carbonate

Copper carbonate is a nicely colored copper salt used as a pigment. Its formula is often stated to be CuCO3 but Cu3(OH)2(CO3)2 and (Cu2(OH)2CO3) are closer to the truth. I plan to use it to catalyze the decarboxylation of niacin to pyridine, as well as to make calcium copper silicate.

Copper carbonate is relatively easy to make. I made some.

To a 500ml beaker I added 20g of copper sulphate pentahydrate and 150ml of water. The mixture was stirred to give a clear blue solution. With strong stirring, I slowly added 20g of sodium bicarbonate. As I added the sodium bicarbonate, the mixture started foaming and a wonderful green-blue colored precipitate of copper carbonate gradually formed. Once all the sodium bicarbonate had been added, the mixture was filtered to collect the copper carbonate product. After drying, I was left with 31g of copper carbonate.

NaHCO3 + CuSO4 ==> Cu(HCO3)2 + Na2SO4  /  Cu(HCO3)2 ==> CuCO3 + H2O + CO2