S-So2-SO3-H2SO4-CA(HSO4)2- - ZnSO4-Zn(OH)2
S + O₂ = SO₂ 2SO₂ + O₂ = 2SO₃ SO₃ + H₂O =H₂SO₄ H₂SO₄ + Ca(OH)₂ = Ca(HSO₄)₂ + H₂O ZnSO₄ + 2KOh = Zn(OH)₂ + H₂SO₄