Cu + KNO3 + H2SO4 => Cu(SO4)2­ + NO­ + K2SO4 + H2O

\[\begin{array}{*{20}{l}} {\left. {2x} \right|Cu \to C{u^{ + 2}}{\text{ }} + 2e\;{\text{ }}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\;} \\ \begin{gathered} \left. {3x} \right|{N^{ + 5}}{\text{ }} + 3e \to {N^{ + 2}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\; \hfill \\ \end{gathered} \\ {3Cu{\text{ }} + {\text{ }}2KN{O_3}{\text{ }} + {\text{ }}4{H_2}S{O_4}{\text{ }} \to {\text{ }}3CuS{O_4}{\text{ }} + {\text{ }}2NO{\text{ }} + {\text{ }}{K_2}S{O_4}{\text{ }} + {\text{ }}4{H_2}O} \end{array}\]

Đáp án:

3Cu+4H₂SO₄+2KNO₃→4H₂O+2NO+K₂SO₄+3CuSO₄

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