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词条 Chlorite
释义

  1. Compounds

  2. Structure and properties

  3. Uses

  4. Other oxyanions

  5. See also

  6. References

{{about||the mineral type|chlorite group|the neutral chemical compound|chlorine dioxide}}{{Chembox
| ImageFile = Chlorition.png
| ImageSize = 100
| ImageAlt =
| ImageName = The chlorite ion
| ImageFile1 = Chlorite-3D-vdW.png
| ImageSize1 = 100
| ImageAlt1 =
| ImageName1 = The chlorite ion
| IUPACName = Chlorite
| OtherNames =
| Section1 = {{Chembox Identifiers
| CASNo = 14998-27-7
| EINECS = 215-285-9
| PubChem = 197148
| ChemSpiderID = 170734
| SMILES = [O-][Cl+][O-]
| StdInChI = 1S/ClHO2/c2-1-3/h(H,2,3)/p-1
| StdInChIKey = QBWCMBCROVPCKQ-UHFFFAOYSA-M
| Section2 = {{Chembox Properties
| Formula = {{chem|ClO|2|−}}
| MolarMass = 67.452
| Appearance =
| Density =
| MeltingPt =
| BoilingPt =
| Solubility =
| ConjugateAcid = Chlorous acid
| Section3 = {{Chembox Hazards
| MainHazards =
| FlashPt =
| AutoignitionPt =
}}

The chlorite ion, or chlorine dioxide anion, is {{chem|ClO|2|−}}. A chlorite (compound) is a compound that contains this group,

with chlorine in oxidation state +3. Chlorites are also known as salts of chlorous acid.

Compounds

{{See also|Category:Chlorites}}

The free acid, chlorous acid HClO2, is the least stable oxoacid of chlorine and has only been observed as an aqueous solution at low concentrations. Since it cannot be concentrated, it is not a commercial product. The alkali metal and alkaline earth metal compounds are all colorless or pale yellow, with sodium chlorite (NaClO2) being the only commercially important chlorite. Heavy metal chlorites (Ag+, Hg+, Tl+, Pb2+, and also Cu2+ and {{chem|NH|4|+}}) are unstable and decompose explosively with heat or shock.[1]

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).

Structure and properties

The chlorite ion adopts a bent molecular geometry, due to the effects of the lone pairs on the chlorine atom, with an O–Cl–O bond angle of 111° and Cl–O bond lengths of 156 pm.[1]

Chlorite is the strongest oxidiser of the chlorine oxyanions on the basis of standard half cell potentials.[2]

Ion Acidic reaction E° (V) Neutral/basic reaction E° (V)
Hypochlorite H+ + HOCl + e → {{1/2}} Cl2(g) + H2O 1.63 ClO + H2O + 2 e → Cl + 2 OH 0.89
Chlorite 3 H+ + HOClO + 3 e → {{1/2}} Cl2(g) + 2 H2O 1.64ClO|2|−}} + 2 H2O + 4 e → Cl + 4 OH0.78
Chlorate+ + {{chem>ClO|3|−}} + 5 e → {{1/2}} Cl2(g) + 3 H2O1.47ClO|3|−}} + 3 H2O + 6 e → Cl + 6 OH0.63
Perchlorate+ + {{chem>ClO|4|−}} + 7 e → {{1/2}} Cl2(g) + 4 H2O1.42ClO|4|−}} + 4 H2O + 8 e → Cl + 8 OH0.56

Uses

The most important chlorite is sodium chlorite (NaClO2); this is used in the bleaching of textiles, pulp, and paper, however despite its strongly oxidizing nature it is often not used directly being instead used to generate the neutral species chlorine dioxide (ClO2), normally via a reaction with HCl:

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

Other oxyanions

Several oxyanions of chlorine exist, in which it can assume oxidation states of −1, +1, +3, +5, or +7 within the corresponding anions Cl, ClO, {{chem|ClO|2|−}}, {{chem|ClO|3|−}}, or {{chem|ClO|4|−}}, known commonly and respectively as chloride, hypochlorite, chlorite, chlorate, and perchlorate. These are part of a greater family of other chlorine oxides.

oxidation state −1 +1 +3 +5 +7
anion named chloride hypochlorite chlorite chlorate perchlorate
formula Cl ClOClO|2|−}}ClO|3|−}}ClO|4|−}}
structure

See also

  • Tetrachlorodecaoxide, a chlorite-based drug
  • Chloryl, {{chem|ClO|2|+}}

References

1. ^{{cite book|last1=Greenwood|first1=N.N.|last2=Earnshaw|first2=A.|title=Chemistry of the elements|date=2006|publisher=Butterworth-Heinemann|location=Oxford|isbn=0750633654|page=861|edition=2nd}}
2. ^{{Cotton&Wilkinson5th|page=564}}
  • Kirk-Othmer Concise Encyclopedia of Chemistry, Martin Grayson, Editor, John Wiley & Sons, Inc., 1985

2 : Chlorites|Chlorine oxides

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