Sulfurous Acid

S(s) + O₂(g) = SO₂(g)

SO₂(g) + H₂O(l) = H₂SO₃(aq)

H₂SO₃(aq) = H⁺ + HSO₃^-(aq)

H₂SO₃(aq) + NaOH(aq) = H₂O(l) + NaHSO₃(aq)

H₂SO₃(aq) + 2 NaOH(aq) = 2 H₂O(l) + Na₂SO₃(aq)