Chlorite
Overview
 
The chlorite ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

 is ClO2. A chlorite (compound) is a compound that contains this group,
with chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

 in oxidation state
Oxidation state
In chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. The formal oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. Oxidation states are typically represented by...

 +3. Chlorites are also known as salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...

s of chlorous acid
Chlorous acid
Chlorous acid is an inorganic compound with the formula HClO2. It is a weak acid. Chlorine has oxidation state +3 in this acid. The pure substance is unstable, disproportionating to hypochlorous acid and chloric acid :Although the acid is difficult to obtain in pure substance, the conjugate base,...

.
Chlorine can assume oxidation states of −1, +1, +3, +5, or +7 within the corresponding anions Cl, ClO, ClO2, ClO3, or ClO4, known commonly and respectively as chloride, hypochlorite, chlorite, chlorate, and perchlorate.
Encyclopedia
The chlorite ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

 is ClO2. A chlorite (compound) is a compound that contains this group,
with chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

 in oxidation state
Oxidation state
In chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. The formal oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. Oxidation states are typically represented by...

 +3. Chlorites are also known as salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...

s of chlorous acid
Chlorous acid
Chlorous acid is an inorganic compound with the formula HClO2. It is a weak acid. Chlorine has oxidation state +3 in this acid. The pure substance is unstable, disproportionating to hypochlorous acid and chloric acid :Although the acid is difficult to obtain in pure substance, the conjugate base,...

.

Oxidation states

Chlorine can assume oxidation states of −1, +1, +3, +5, or +7 within the corresponding anions Cl, ClO, ClO2, ClO3, or ClO4, known commonly and respectively as chloride, hypochlorite, chlorite, chlorate, and perchlorate. An additional oxidation state of +4 is seen in the neutral compound chlorine dioxide
Chlorine dioxide
Chlorine dioxide is a chemical compound with the formula ClO2. This yellowish-green gas crystallizes as bright orange crystals at −59 °C. As one of several oxides of chlorine, it is a potent and useful oxidizing agent used in water treatment and in bleaching....

 ClO2, which has the same structure as chlorite ClO2 and the cation chloryl
Chloryl
In chemistry, chloryl refers to the red-colored cation having the chemical formula . It is polyatomic ion, structurally identical to chlorite and having the same chemical formula but with chlorine in the +5 oxidation state rather than +3...

 (ClO2+).
oxidation state −1 +1 +3 +5 +7
anion named chloride
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...

hypochlorite
Hypochlorite
The hypochlorite ion, also known as chlorate anion is ClO−. A hypochlorite compound is a chemical compound containing this group, with chlorine in oxidation state +1.Hypochlorites are the salts of hypochlorous acid...

chlorite chlorate
Chlorate
The chlorate anion has the formula ClO. In this case, the chlorine atom is in the +5 oxidation state. "Chlorate" can also refer to chemical compounds containing this anion; chlorates are the salts of chloric acid. "Chlorate", when followed by a roman numeral in parentheses, e.g...

perchlorate
Perchlorate
Perchlorates are the salts derived from perchloric acid . They occur both naturally and through manufacturing. They have been used as a medicine for more than 50 years to treat thyroid gland disorders. They are used extensively within the pyrotechnics industry, and ammonium perchlorate is also a...

formula Cl- ClO ClO2 ClO3 ClO4
structure

Some chlorite compounds

  • sodium chlorite
    Sodium chlorite
    Sodium chlorite is a chemical compound used in the manufacture of paper.-Use:The main application of sodium chlorite is the generation of chlorine dioxide for bleaching and stripping of textiles, pulp, and paper. It is also used for disinfection of a few municipal water treatment plants after...

    , NaClO2
  • magnesium chlorite, Mg(ClO2)2

Manufacture

The free acid, chlorous acid
Chlorous acid
Chlorous acid is an inorganic compound with the formula HClO2. It is a weak acid. Chlorine has oxidation state +3 in this acid. The pure substance is unstable, disproportionating to hypochlorous acid and chloric acid :Although the acid is difficult to obtain in pure substance, the conjugate base,...

, 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
Sodium chlorite
Sodium chlorite is a chemical compound used in the manufacture of paper.-Use:The main application of sodium chlorite is the generation of chlorine dioxide for bleaching and stripping of textiles, pulp, and paper. It is also used for disinfection of a few municipal water treatment plants after...

, 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
Sodium chlorate
Sodium chlorate is a chemical compound with the chemical formula . 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...

, NaClO3. First, the explosively unstable gas chlorine dioxide
Chlorine dioxide
Chlorine dioxide is a chemical compound with the formula ClO2. This yellowish-green gas crystallizes as bright orange crystals at −59 °C. As one of several oxides of chlorine, it is a potent and useful oxidizing agent used in water treatment and in bleaching....

, 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).

H2SO4(aq) + NaClO3(s) → NaHSO4(aq) + HClO3(aq)

3HClO3(aq) → 2ClO2(g) + HClO4(aq) + H2O(l)

(Other routes for the preparation of chlorine dioxide are available depending on the initial salt).

The chlorine dioxide is then absorbed into an alkaline solution and reduced with hydrogen peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...

, H2O2 yielding sodium chlorite
Sodium chlorite
Sodium chlorite is a chemical compound used in the manufacture of paper.-Use:The main application of sodium chlorite is the generation of chlorine dioxide for bleaching and stripping of textiles, pulp, and paper. It is also used for disinfection of a few municipal water treatment plants after...

 (NaClO2). (Sodium, Na+, spectator ions are not shown in the following equations).

2ClO2(g) + 2OH- → ClO2-(aq) + ClO3-(aq) + H2O(l)

ClO3-(aq) + H2O2(l) → ClO2-(aq) + H2O(l) + O2(g)

Usage

The main application of sodium chlorite
Sodium chlorite
Sodium chlorite is a chemical compound used in the manufacture of paper.-Use:The main application of sodium chlorite is the generation of chlorine dioxide for bleaching and stripping of textiles, pulp, and paper. It is also used for disinfection of a few municipal water treatment plants after...

 is the generation of chlorine dioxide for bleaching and stripping of textiles, pulp, and paper. It is also used for disinfection in a few municipal water treatment plants after conversion to chlorine dioxide
Chlorine dioxide
Chlorine dioxide is a chemical compound with the formula ClO2. This yellowish-green gas crystallizes as bright orange crystals at −59 °C. As one of several oxides of chlorine, it is a potent and useful oxidizing agent used in water treatment and in bleaching....

. An advantage in this application, as compared to the more commonly used chlorine, is that trihalomethanes are not produced from organic contaminants. In the European Union however, the use of Sodium chlorite
Sodium chlorite
Sodium chlorite is a chemical compound used in the manufacture of paper.-Use:The main application of sodium chlorite is the generation of chlorine dioxide for bleaching and stripping of textiles, pulp, and paper. It is also used for disinfection of a few municipal water treatment plants after...

 has been phased out by 24-10-2009 for use as certain types of biocides: Product-type(PT) 2: Private area and public health area disinfectants and other biocidal products, PT 3: Veterinary hygiene biocidal products, PT 4: Food and feed area disinfectants and PT 5: Drinking water disinfectants. Since September 2006, its application as molluscicide (PT 16) is forbidden as well.
Sodium chlorite
Sodium chlorite
Sodium chlorite is a chemical compound used in the manufacture of paper.-Use:The main application of sodium chlorite is the generation of chlorine dioxide for bleaching and stripping of textiles, pulp, and paper. It is also used for disinfection of a few municipal water treatment plants after...

, NaClO2 also finds application as a component of contact lens cleaning solution under the trade name purite.

Safety

Health related information: see sodium chlorite
Sodium chlorite
Sodium chlorite is a chemical compound used in the manufacture of paper.-Use:The main application of sodium chlorite is the generation of chlorine dioxide for bleaching and stripping of textiles, pulp, and paper. It is also used for disinfection of a few municipal water treatment plants after...

.
Sodium chlorite, like many oxidizers, should be protected from inadvertent contamination by organic materials to avoid the formation of an explosive mixture.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK