Sodium chlorate

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Sodium chlorate
Sodium chlorate
General
Other names Sodium chlorate(V)
Molecular formula NaClO3
Molar mass 106.44 g/mol
Appearance white solid
CAS number [7775-09-9]
Properties
Density and phase 2.5 g/cm³, solid
Solubility in water 101.0 g/100 ml (20 °C)
Melting point 248 °C
Boiling point ~300 °C decomp.
Structure
Coordination
geometry
 ?
Crystal structure  ?
Hazards
MSDS External MSDS
EU classification Oxidant (O)
Harmful (Xn)
Dangerous for
the environment (N)
NFPA 704

0
1
2
OX
R-phrases R9, R22, R51/53
S-phrases S2, S13, S17,
S46, S61
Flash point none
Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Related compounds
Other anions Sodium bromate
Sodium iodate
Other cations Ammonium chlorate
Potassium chlorate
Related compounds Sodium chloride
Sodium hypochlorite
Sodium chlorite
Sodium perchlorate
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Infobox disclaimer and references

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.

Structure of sodium chlorate

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.

Contents

[edit] Uses

Sodium chlorate is used as a non-selective herbicide. It is considered phytotoxic to all green plant parts. It can also kill through root absorption. Sodium chlorate may be used to control morning glory, Canada thistle, johnson grass, bamboo, ragwort and St John's wort. The herbicide is mainly used on non-crop land for spot treatment and for total vegetation control on roadsides, fenceways, ditches and suchlike. Sodium chlorate is also used as a defoliant and desiccant for cotton, safflower, corn, flax, peppers, soybeans, grain sorghum, southern peas, dry beans, rice and sunflowers. If used in combination with atrazine, it increases the persistence of the effect. If used in combination with 2,4-D, it improves performance of the material. Sodium chlorate has a soil-sterilant effect. Mixing with other herbicides in aqueous solution is possible to some extent, so long as they are not susceptible to oxidation.

Sodium chlorate comes in dust, spray and granule formulations. There is a risk of fire and explosion in dry mixtures with other substances, especially organic materials, that is other herbicides, sulfur, phosphorus, powdered metals, strong acids. Particularly, when mixed with sugar it has explosive properties. The ease of availability of these two ingredients make it a common choice for home made bombs. Marketed formulations contain a fire depressant, but this has little effect if deliberately ignited. Most commercially available Chlorate weedkillers contain approximately 53% Sodium Chlorate with the balance being a fire depressant such as sodium metaborate or ammonium phosphates.

[edit] Trade Names

The active ingredient sodium chlorate is found in a variety of commercial herbicides. Some trade names for products containing sodium chlorate include Atlacide, Defol, De-Fol-Ate, Drop-Leaf, Fall, Harvest-Aid, Kusatol, Leafex, and Tumbleaf. The compound may be used in combination with other herbicides such as atrazine, 2,4-D, bromacil, diuron, and sodium metaborate. In the United Kingdom there are many brands of Sodium Chlorate Weedkillers. Two well known ones are Doff and Wilkinsons.

[edit] Cultural References

[edit] See also

[edit] Reference

  • "Chlorate de potassium. Chlorate de sodium", Fiche toxicol. n° 217, Paris:Institut national de recherche et de sécurité, 2000. 4pp.

[edit] External links