Câu a:

(1) Fe₂(SO₄)₃ + 3BaCl₂ → 3BaSO₄↓ + 2FeCl₃

(2) FeCl₃ + 3NaOH → Fe(OH)₃↓ + 3NaCl

(3) Fe₂(SO₄)₃ + 6NaOH → 2Fe(OH)₃↓ + 3Na₂SO₄

(4) 2Fe(OH)₃ + 3H₂SO₄ → Fe₂(SO₄)₃ + 6H₂O

(5) 2Fe(OH)₃ → Fe₂O₃ + 3H₂O

(6) Fe₂O₃ + 3H₂SO₄ → Fe₂(SO₄)₃ + 3H₂O.

Câu b:

(1) 2Cu + O₂ → 2CuO

(2) CuO + H₂ → Cu + H₂O

(3) CuO + 2HCl → CuCl₂ + H₂O

(4) CuCl₂ + 2NaOH → Cu(OH)₂↓ + 2NaCl

(5) Cu(OH)₂ + 2HCl → CuCl₂ + 2H₂O

(6) Cu(OH)₂ → CuO + H₂O