1) Cu(OH)₂→CuO→CuCI₂→Cu(OH)₂
Cu(OH)₂=CuO+H₂O
CuO+2HCI=CuCI₂+H₂O
CuCI₂+2NaOH=Cu(OH)₂↓+2NaCI
2) S→SO₂→SO₃→H₂SO₄→BaSO₄
S+O₂=SO₂
2SO₂+O₂=2SO₃
SO₃+H₂O=H₂SO₄
H₂SO₄+BaCI₂=BaSO₄↓+2HCI
3)Fe(OH)₃→Fe₂O₃→Fe₂(SO₄)₃→Fe(OH)₃
2Fe(OH)₃=Fe₂O₃+3H₂O
Fe₂O₃+3H₂SO₄=Fe₂(SO₄)₃+3H₂O
Fe₂(SO₄)₃+6NaOH=2Fe(OH)₃↓+3Na₂SO₄
4) S→SO₂→H₂SO₃→K₂SO₃
I I
Na₂SO₃
S+O₂=SO₂
SO₂+H₂O=H₂SO₃
H₂SO₃+2KOH=K₂SO₃+2H₂O
SO₂+Na₂O=Na₂SO₃
Na₂SO₃+2HCI=2NaCI+H₂SO₃