Sodium chlorate

Chlorate of sodium

Colorless, crystalline, water-soluble, hygroscopic solid

Fixed

2.49 g · cm -3 ( 15 ° C)

248 ° C

Decomposition above 300 ° C.

Well in water (916 g · l-1 at 20 ° C)

1.5151

Risk

1200 mg · kg -1 ( LD50, rat, oral)

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Sodium chlorate (deprecated also chlorate sodium) NaClO 3 is the sodium salt of chloroacetic acid ( HClO3 ).

Representation and extraction

Sodium chlorate is produced by electrolysis of sodium chloride solution. The chlorine formed at the anode (Cl2 ) is responsive to hypochlorite, which passes in turn through anodic oxidation in chlorate.

It can also be produced by introduction of chlorine gas in a warm NaOH - solution. With subsequent crystallization, the sodium chlorate.

Properties

Sodium chlorate is a colorless, water-soluble, cubic crystals. It disproportionates at elevated temperature, first in sodium perchlorate and sodium chloride, with sodium perchlorate further decomposes if heated more sodium chloride and oxygen.

Aqueous solutions react weakly acidic.

Use

SC is mostly used as a bleaching agent in the paper industry and is also suitable for the textile industry. Elemental chlorine -free bleaching ( ECF ) in pulp production resulted in the 90s of last century to a strongly growing production of sodium chlorate. Already in 1985, almost 80 % of the quantities produced were used in the release of chlorine dioxide. Currently, about 90 % of world production are processed into chlorine dioxide. Furthermore, sodium chlorate is used for the production of sodium chlorite, perchlorates and as a weed killer. Chlorates, however, are no longer permitted within the EU as active substances in plant protection products; a well-known trade name of chlorathaltigen herbicides was " UnkrautEx ". It once served as the oxidant in some explosives, but these are long gone prepared for their handling uncertainty.

Sodium chlorate is used in chemical oxygen generators ( oxygen candles ), such as they are in passenger aircraft above each seat; they are connected by tubing with an oxygen mask. For pressure loss these masks fall from a small chamber above the seat The oxygen generator is activated by the appointment of the mask. In this case, iron ( II) oxide and oxygen, the iron reacts with sodium chlorate to sodium chloride.

The heat released in this reaction, the generator up to 260 degrees Celsius hot.