$\rm \mathop{Cu}\limits^{0} + H\mathop{N}\limits^{+5}O_3 \to \mathop{Cu}\limits^{+2}(NO_3)_2 + \mathop{N}\limits^{+4}O_2 + H_2O$

Chất khử: $\rm Cu $

Chất oxi `-` hóa: $\rm HNO_3$

Quá trình oxi hóa ` -` khử:

$\begin{array}{c|cc} \rm{1\times \;}&\rm{\mathop{Cu}\limits^{0}\longrightarrow\mathop{Cu}\limits^{+2}+2e}\\\rm {2\times\;}&\rm{\mathop{N}\limits^{+5}+1e\longrightarrow\mathop{N}\limits^{+4}}\\\end{array}$

Cân bằng:

$\rm Cu + 4HNO_3 \to Cu(NO_3)_2 + 2NO_2 + 2H_2O$