Pure Copper ( II ) oxide is better prepared by heating copper ( II ) nitrate , copper ( II ) hydroxide or copper ( II ) carbonate : 2 Cu ( NO3 ) 2 → 2 CuO + 4 NO2 + O2 Cu ( OH ) 2 ( s ) → CuO ( s ) + H2O ( l ) CuCO3 → CuO + CO2 Copper ( II ) oxide is a amphoteric oxide , so it dissolves in mineral acids such as hydrochloric acid , sulfuric acid or nitric acid to give the corresponding copper ( II ) salts : CuO + 2 HNO3 → Cu ( NO3 ) 2 + H2O CuO + 2 HCl → CuCl2 + H2O CuO + H2SO4 → CuSO4 + H2O It reacts with concentrated alkali to form the corresponding cuprate salts : 2 XOH + CuO + H2O → X2 ( Cu ( OH ) 4 ) It can also be reduced to copper metal using hydrogen or carbon monoxide : CuO + H2 → Cu + H2O CuO + CO → Cu + CO2 A laboratory method for preparing copper ( II ) oxide is to electrolyze water containing sodium bicarbonate at a moderate voltage with a copper anode , collect the mixture of insoluble copper hydroxide , basic copper carbonate , and copper carbonate precipitates , and heat it to release the hydrogen , carbon and excess oxygen .
It can also be made by heating copper ( II ) carbonate or copper ( II ) nitrate .