Mohr's Salt, ammonium iron sulfate, is a double salt of iron sulfate and ammonium sulfate, with the formula [NH₄]₄[Fe][SO₄]₄·6H₂O. Mohr's salt is preferred over iron(II) sulfate for titration purposes as it is much less affected by oxygen in the air than iron(II) sulfate, solutions of which tend to oxidise to iron(III). The oxidation of solutions of iron(II) is very pH dependent, occurring much more readily at high pH. The ammonium ions make solutions of Mohr's salt slightly acidic, which prevents this oxidation occurring. The relevant equation for this is:
4 Fe²⁺ + O₂ + (4+2x) H₂O 2 Fe₂O₃.xH₂O + 8 H⁺
The presence of protons keeps this equilibrium to the left, the Fe(II) side.

The free acid, chlorous acid, HClO2, is only stable at low concentrations. Since it cannot be concentrated, it is not a commercial product. However, the corresponding sodium salt, sodium chlorite, NaClO2 is stable and inexpensive enough to be commercially available. The corresponding salts of heavy metals (Ag+, Hg+, Tl+, Pb2+, and also Cu2+ and NH4+) decompose explosively with heat or shock.

Sodium chlorite is derived indirectly from sodium chlorate, NaClO3. First, the explosively unstable gas chlorine dioxide, ClO2 is produced by reducing sodium chlorate in a strong acid solution with a suitable reducing agent (for example, sodium chloride, sulfur dioxide, or hydrochloric acid). The chlorine dioxide is then absorbed into an alkaline solution and reduced with hydrogen peroxide, H2O2 yielding sodium chlorite.

Sodium chlorate (NaClO₃) is an oxidizing agent. It is mostly used to produce chlorine dioxide for bleaching paper pulp, but is also used as a herbicide and to prepare other chlorates. Production in the United States is about 441000 tons per year.

When pure, it is a white crystalline powder that is readily soluble in water. It is hygroscopic. It decomposes above 250 °C to release oxygen and leave sodium chloride. It is synthesised from the electrolysis of hot sodium chloride solution in a mixed electrode tank. It can also be synthesised by passing chlorine gas to a hot sodium hydroxide solution. It is then purified by crystallization.