Question

State how would you prepare copper (II) oxide from
(a) copper nitrate.
(b) copper carbonate.
(c) copper sulphate.

Answer 1

(a) On heating, copper nitrate decomposes to give copper (II) oxide, nitrogen dioxide and oxygen.

$$\begin{gathered} 2\mathrm{Cu}(\mathrm{NO}3{)}_2\stackrel{\mathrm{Heat}}{\to }2\mathrm{CuO}+4{\mathrm{NO}}_2+{\mathrm{O}}_2 \\ \mathrm{Copper}\mathrm{nitrate}\mathrm{Copper}(\mathrm{II})\mathrm{oxide} \end{gathered}$$

(b) On heating, copper carbonate decomposes to give ​copper (II) oxide and liberates carbon dioxide gas.

$$\begin{gathered} {\mathrm{CuCO}}_3\stackrel{\mathrm{Heat}}{\to }\mathrm{CuO}+{\mathrm{CO}}_2 \\ \mathrm{Copper}\mathrm{carbonate}\mathrm{Copper}\left(\mathrm{II}\right) \\ \mathrm{oxide} \end{gathered}$$

(c) Copper sulphate reacts with a base like sodium hydroxide to form copper hydroxide and sodium sulphate by double
decomposition reaction. On heating, copper hydroxide further decomposes to give copper (II) oxide.

$$\begin{gathered} {\mathrm{CuSO}}_4+2\mathrm{NaOH}\to \mathrm{Cu}(\mathrm{OH}{)}_2+{\mathrm{Na}}_2{\mathrm{SO}}_4 \\ \mathrm{Copper}\mathrm{hydroxide} \\ \mathrm{Cu}(\mathrm{OH}{)}_2\stackrel{\mathrm{Heat}}{\to }\mathrm{CuO}+{\mathrm{H}}_2\mathrm{O} \\ \mathrm{Copper}\mathrm{hydroxide}\mathrm{Copper}\left(\mathrm{II}\right)\mathrm{oxide} \end{gathered}$$