Cu → CuO → CuSO4 → CuCl2 → Cu(OH)2 → CuO ↓ Cu(NO)2

Răspuns:
2Cu + O₂ → 2CuO
CuO + 2HNO₃ → Cu(NO₃)₂ + H₂O
CuO + H₂SO₄ → CuSO₄ + H₂O
CuSO₄ + BaCl₂ → BaSO₄↓ + CuCl₂
CuCl₂ + 2NaOH → Cu(OH)₂↓ + 2NaCl
Cu(OH)₂ → CuO + H₂O
-Mihai