<Dd> 2 CuSO + 4 NaHCO → Cu (OH) CO + 2 Na SO + 3 CO + H O </Dd> <P> Basic copper carbonate is decomposed by acids, such as solutions of hydrochloric acid HCl, into the copper (II) salt and carbon dioxide . </P> <P> "Copper carbonate" was the first compound to be broken down into several compounds: in 1794 by the French chemist Joseph Louis Proust (1754--1826) thermally decomposed it to CO and CuO, cupric oxide, a black solid . </P> <P> The basic copper carbonates, malachite and azurite, both decompose forming CO and CuO, cupric oxide . </P>

Copper carbonate on heating gives a black residue of copper oxide