Sodium chlorate

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Not to be confused with Sodium chlorite.
Sodium chlorate
Sodium chlorate crystals.jpg
Sodium chlorate crystals
Names
IUPAC name
Sodium chlorate
Other names
Asex
Polybor-chlorate
Sodium chlorate(V)
Properties
NaClO3
Molar mass 106.44 g/mol
Appearance White crystalline solid
Odor Odorless
Density 2.49 g/cm3 (15 °C)
2.54 g/cm3 (20.2 °C)
Melting point 248 °C (478 °F; 521 K)
Boiling point Decomposes
79 g/100 ml (0 °C)
89 g/100 ml (10 °C)
105.7 g/100 ml (25 °C)
125 g/100 ml (40 °C)
220.4 g/100 ml (100 °C)
Solubility Soluble in glycerol, hydrazine, methanol
Slightly soluble in liq. ammonia, ethanol
Sparingly soluble in acetone
Insoluble in hydrocarbons
Solubility in ethanol 14.7 g/100 g
Solubility in ethylene glycol 16 g/100 g (25 °C)
Solubility in glycerol 20 g/100 g (15.5 °C)
Solubility in hydrazine 66 g/100 g (25 °C)
Solubility in methanol 51.35 g/100 g (25 °C)
Vapor pressure ~ 0 mmHg
Thermochemistry
129.7 J·mol-1·K-1
-365.4 kJ/mol
Hazards
Safety data sheet Sigma-Aldrich
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
6,500 mg/kg (rats, oral)
700 mg/kg (dogs, oral)
Related compounds
Related compounds
Sodium hypochlorite
Sodium chlorite
Sodium perchlorate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Sodium chlorate is an inorganic compound, comprised of equal numbers of sodium cations and chlorate anions, giving it the fomula NaClO3. It is a very powerful oxidizer.

Properties

Chemical

It is a strong oxidizing agent, easily supplying oxygen to combustibles. It decomposes above 300 °C yeilding oxygen and sodium chloride.

2 NaClO3 → 2 NaCl + 3 O2

Sodium chlorate will react with potassium chloride to precipitate potassium chlorate:

KCl + NaClO3 → NaCl + KClO3

Physical

Sodium chlorate is a colorless or white crystalline solid with a cubic crystal structure. It is soluble in water, methanol, glycerol, hydrazine and slightly soluble in ethanol and ammonia. Because sodium chlorate is hygroscopic, potassium chlorate is often preferred for use as an oxidizer.

Availability

It can be bought as "weed killer" at a hardware store, or it can be bought online. Many countries, however, have banned sodium chlorate weed killers.

Its sale is banned in the EU.

Preparation

Sodium chlorate can be produced by boiling bleach, which causes it to disproportionate into sodium chlorate and sodium chloride.

A more efficient way of producing sodium chlorate is via the electrolysis of a supersaturated sodium chloride solution with an appropriate anode at ~5 volts DC.

Although the exact reactions are very complex, the basic overall equation is:

NaCl + 3 H2O → NaClO3 + 3 H2

Projects

  • Preparation of potassium chlorate
  • Make a dry chemical oxygen generator: Heat is generated by oxidation of a small amount of iron powder mixed with the sodium chlorate, and the reaction consumes less oxygen than is produced. Barium peroxide is used to absorb the chlorine which is a minor product in the decomposition.[1] An ignitor charge is activated by pulling on the emergency mask. Similarly, the Solidox welding system used pellets of sodium chlorate mixed with combustible fibers to generate oxygen.

Handling

Safety

Powerful oxidizer! Fire hazard! Keep away from any flammables.

Due to its oxidative nature, sodium chlorate can be very toxic if ingested. The oxidative effect on hemoglobin leads to methaemoglobin formation, which is followed by denaturation of the globin protein and a cross-linking of erythrocytemembrane proteins with resultant damage to the membrane enzymes. This leads to increased permeability of the membrane, and severe hemolysis. The denaturation of hemoglobin overwhelms the capacity of the G6PD metabolic pathway. In addition, this enzyme is directly denatured by chlorate reducing its activity.

Storage

Sodium chlorate should be stored in closed bottles, away from any flammable materials and strong acids. Since it's hygroscopic, it should be kept in a dry place.

Disposal

Sodium chlorate can be neutralized with sodium or potassium metabisulfite.

References

  1. http://en.wikipedia.org/wiki/Sodium_chlorate#cite_note-8

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