1) Ba(OH)₂ + 2HCl → BaCl₂ + 2H₂O2) CuSO₄ + 2NaOH → Cu(OH)₂ + Na₂SO₄3) Na₂S + Ba(OH)₂ → BaS + 2NaOH4) CuSO₄ + Na₂S → CuS + Na₂SO₄
1) Ba(OH)₂ + 2HCl → BaCl₂ + 2H₂O
2) CuSO₄ + 2NaOH → Cu(OH)₂ + Na₂SO₄
3) Na₂S + Ba(OH)₂ → BaS + 2NaOH
4) CuSO₄ + Na₂S → CuS + Na₂SO₄