Chlorite

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A chlorite is a compound that contains the chlorite ion, ClO
2
.

General properties

Chlorite is the strongest oxidizer of the chlorine oxyanions, on the basis of standard half cell potentials.[1]

Chlorite salts, like sodium chlorite reacts with acids and elemental chlorine to yield chlorine dioxide.

2 NaClO2 + Cl2 → 2 ClO2 + 3 NaCl + H2O
5 NaClO2 + 4 HCl → 5 NaCl + 4 ClO2 + 2 H2O

The parental acid, chlorous acid is unstable and decomposes to hypochlorous and chloric acids

Salts like ammonium chlorite, are impossible to obtain, as the chlorous anion will oxidize the ammonium cation.

Availability

Chlorites, like sodium or potassium chlorite can be purchased from lab suppliers.

Preparation

Sodium chlorite can be made by reducing sodium chlorate in a strong acid solution with a suitable reducing agent, like sodium sulfite, sulfur dioxide or even hydrochloric acid. This produces chlorine dioxide, which is then absorbed into an alkaline solution and reduced with hydrogen peroxide, yielding sodium chlorite. The final product will always contain 20% sodium chloride.

Reaction of chlorine with sodium nitrate will yield sodium chlorite and nitrosyl chloride.

NaNO3 + Cl2 → NaClO2 + NOCl

Similar techniques can be done for other chlorite salts.

Safety and handling

Chlorites are powerful oxidizers.

References

  1. Cotton, F. Albert; Wilkinson, Geoffrey (1988), Advanced Inorganic Chemistry (5th ed.), New York: Wiley-Interscience, p. 564

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