Sodium chlorate

Crystal structure
__ Na + __ Cl 5+ __ O 2−
Crystal system	cubic
Space group	P 2 1 3 (No. 198)
Lattice parameters	a 6.57584 Å
General
Surname	Sodium chlorate
other names	sodium chlorate
Ratio formula	NaClO 3
Brief description	colorless, crystalline, water-soluble, solid
External identifiers / databases
CAS number 7775-09-9 EC number 231-887-4 ECHA InfoCard 100,028,989 PubChem 516902 ChemSpider 22895 Wikidata Q407446
properties
Molar mass	106.44 g mol −1
Physical state	firmly
density	2.49 g cm −3 (15 ° C)
Melting point	248 ° C
boiling point	Decomposition from 255 ° C
solubility	good in water (916 g l −1 at 20 ° C)
Refractive index	1.5151
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 271-302-411 P: 220-273
Toxicological data	1200 mg kg −1 ( LD 50 ,  rat ,  oral )
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Sodium chlorate (obsolete also chlorate sodium ) NaClO ₃ is the sodium salt of perchloric acid (HClO ₃ ).

Presentation and extraction

Sodium chlorate is made by the electrolysis of sodium chloride solution. The chlorine (Cl ₂ ) formed at the anode reacts to form hypochlorite , which in turn converts to chlorate through anodic oxidation .

It can also be made by introducing chlorine gas into a warm NaOH solution. The sodium chlorate is obtained with subsequent crystallization.

properties

Sodium chlorate forms colorless, water-soluble, cubic crystals . It disproportionates at elevated temperature initially into sodium perchlorate and sodium chloride,

${\displaystyle {\ce {4NaClO3 -> NaCl + 3NaClO4}}}$

whereby sodium perchlorate further breaks down into sodium chloride and oxygen when heated more strongly . Aqueous solutions are weakly acidic. Sodium chlorate crystallizes cubically , space group P 2 ₁ 3 (space group no. 198) with the lattice parameter a  = 6.57584  Å .

use

IG Farben advertising for sodium chlorate as a weed killer

Sodium chlorate is mostly used as a bleaching agent in the paper industry and is also suitable for the textile industry . Elemental chlorine-free bleaching (ECF bleaching) in pulp production led to a rapidly growing production of sodium chlorate in the 1990s. As early as 1985, almost 80% of the quantities produced were used to release chlorine dioxide . About 90% of world production is currently processed into chlorine dioxide. Sodium chlorate is also used to produce sodium chlorite , perchlorates and as a herbicide . However, chlorates are no longer permitted as active ingredients in plant protection products within the EU; A well-known trade name for the herbicides containing chlorate was “ WeedEx ”. The maximum levels of residues in food / products that are still possible are regulated by a regulation (EU) . Sodium chlorate used to be used as an oxidant in some explosives, but these have not been manufactured for a long time due to their unsafe handling.

Sodium chlorate is found in chemical oxygen generators such as those located above every seat in passenger aircraft for emergencies; they are connected to an oxygen mask via a hose . If the pressure in the aircraft drops, these masks fall out of a small chamber above the seat. The oxygen generator is activated when the mask is pulled up. The sodium chlorate reacts with iron to form sodium chloride , iron (II) oxide and oxygen .

${\displaystyle {\ce {NaClO3 + Fe -> NaCl + FeO + O2}}}$

The heat released during this reaction causes the generator to reach temperatures of up to 260 degrees Celsius.

Individual evidence

1. ↑ ^{a b c d e f g h i} Entry on sodium chlorate in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
2. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Index of Refraction of Inorganic Crystals, pp. 10-247.
3. ↑ Entry on sodium chlorate in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers and / or distributors can expand the harmonized classification and labeling .
4. ^ ^{A b c} A. F. Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , pp. 478-479.
5. ^ SC Abrahams, JL Bernstein: Remeasurement of optically active NaClO ₃ and NaBrO ₃ . In: Acta Crystallographica . B33, 1977, p. 3601-3604 , doi : 10.1107 / S0567740877011637 ( Open Access ).
6. ↑ Arnold Willmes: Pocket book chemical substances . Harry Deutsch, Frankfurt am Main 2007, ISBN 978-3-8171-1787-1 .
7. ↑ Umweltbundesamt (Ed.): Integrated Avoidance and Reduction of Environmental Pollution (IVU) . Reference document on the best available techniques in the textile industry. July 2003 ( Integrated Avoidance and Reduction of Environmental Pollution (IVU) ( Memento of January 24, 2011 in the Internet Archive ) [PDF; 284 kB ]).
8. ^ NN Greenwood, A. Earnshaw: Chemistry of the elements . VCH, 1988, ISBN 3-527-26169-9 , pp. 1115-1116 .
9. ↑ Bleaching . In: Ullmann's Encyclopedia of Industrial Chemistry . 7th edition. Wiley-VCH , 2007 (Online Edition).
10. ↑ Decision 2008/865 / EC of the Commission of November 10, 2008 on the non-inclusion of chlorate in Annex I of Council Directive 91/414 / EEC and the revocation of the approvals for plant protection products containing this substance
11. ↑ COMMISSION REGULATION (EU) 2020/749. June 4, 2020, accessed June 23, 2020 . 
12. ↑ Max Mahnken: Integration of cabin systems in BWB aircraft configurations . Ed .: University of Applied Sciences Hamburg . 2006 ( Integration of cabin systems in BWB aircraft configurations ( Memento from March 5, 2016 in the Internet Archive ) [PDF; 7.2 MB ]).
13. ↑ Jan Köhler: Processing and description of selected aircraft components . Ed .: University of Applied Sciences Hamburg . Section 7.3 ( Reconditioning and description of selected aircraft components ( Memento from January 15, 2014 in the Internet Archive ) [PDF; 1.9 MB ]).