Copper(II) oxide or cupric oxide (CuO) is the higher oxide of copper. It is a black solid which melts above 1200 °C with some loss of oxygen. It can be formed by heating copper in air, but in this case it is formed along with copper(I) oxide- thus it is better prepared by heating copper(II) nitrate, copper(II) hydroxide or copper(II) carbonate, for example:
CuCO3 → CuO + CO2
Copper(II) oxide is a basic oxide, so it dissolves in mineral acids such as hydrochloric acid, sulfuric acid or nitric acid to give the corresponding copper(II) salts, e.g.
CuO + 2 HNO3 → Cu(NO3)2 + H2O
It can also be reduced to copper metal using hydrogen or carbon monoxide, for example:
H2 + CuO → Cu + H2O
See also
