Compounds of oxygen

Peroxides: O₂^2- (in the peroxyl group, the oxidation state of oxygen is - 1)

Hydrogen peroxide: H₂O₂
sodium peroxide: Na₂O₂

Superoxides: O₂^- (in the superoxyl group, the oxidation state of oxygen is - 1/2)

Peroxy acids: Acids in which an acidic -OH group has been replaced by an -OOH group.  E.g. CH₃C(=O)OOH peroxyacetic acid, PhS(=O)₂OOH benzeneperoxysulfonic acid.

Compounds of sulfur

Sulfates: SO₄^2- = ion sulfate. Examples: Sodium sulfate (Glauber's salt): Na₂SO₄.

Peroxydisulfuric acid: H₂S₂O₈, is an extremely powerful oxidizing agent. The oxidation reaction is slow but can be catalyzed by silver ions.

Dithionous acid, disodium salt (synomims: Sodium dithionite; sodium hydrosulfite, Sodium sulfoxylate; Virtex L; Reductone; Hydrolin; Vatrolite )

Sulfurous acid (H₂SO₃) is the hydrated form of sulfur dioxide (SO₂), a colorless gas with a characteristic choking odor. It is a weak acid which can dissociate into bisulfite (HSO₃^-) and sulfite (SO₃^2-) ions.

H2O (l) + SO2(g) = H2SO3 = HSO3- + H+

HSO3- = SO32- + H+

In acidic solution, the equilibria are shifted to form sulfurous acid, resulting in the evolution of SO₂ gas. Sulfite ion is readily oxidized to sulfate, e.g. by prolonged exposure to atmospheric oxygen or by permanganate. The decolorization of permanganate solutions serves as a convenient test for sulfur dioxide. The sulfites of Na⁺, K⁺, and NH₄⁺ are soluble in water. Most other sulfites are insoluble in water. However, due to the basic nature of SO₃^2-, all sulfites dissolve in acidic solution.