Sodium chlorate, decomposition

Basic oxides of metals such as Co, Mn, Fe, and Cu catalyze the decomposition of chlorate by lowering the decomposition temperature. Consequendy, less fuel is needed and the reaction continues at a lower temperature. Cobalt metal, which forms the basic oxide in situ, lowers the decomposition of pure sodium chlorate from 478 to 280°C while serving as fuel (6,7). Composition of a cobalt-fueled system, compared with an iron-fueled system, is 90 wt % NaClO, 4 wt % Co, and 6 wt % glass fiber vs 86% NaClO, 4% Fe, 6% glass fiber, and 4% BaO. Initiation of the former is at 270°C, compared to 370°C for the iron-fueled candle. Cobalt hydroxide produces a more pronounced lowering of the decomposition temperature than the metal alone, although the water produced by decomposition of the hydroxide to form the oxide is thought to increase chlorine contaminate levels. Alkaline earths and transition-metal ferrates also have catalytic activity and improve chlorine retention (8). 

Sodium Chlorite. The standard enthalpy, Gibbs free energy of formation, and standard entropy for aqueous chlorite ions ate AH° = —66.5 kJ/mol ( — 15.9 kcal/mol), AG = 17.2 kJ/mol (4.1 kcal/mol), and S° = 0.1883 kJ/(molK) (0.045 kcal/(molK)), respectively (107). The thermal decomposition products of NaClO, in the 175—200°C temperature range ate sodium chlorate and sodium chloride (102,109) ... 

Platinum Platinum-coated titanium is the most important anode material for impressed-current cathodic protection in seawater. In electrolysis cells, platinum is attacked if the current waveform varies, if oxygen and chlorine are evolved simultaneously, or if some organic substances are present Nevertheless, platinised titanium is employed in tinplate production in Japan s. Although ruthenium dioxide is the most usual coating for dimensionally stable anodes, platinum/iridium, also deposited by thermal decomposition of a metallo-organic paint, is used in sodium chlorate manufacture. Platinum/ruthenium, applied by an immersion process, is recommended for the cathodes of membrane electrolysis cells. ... 

Sodium chlorate stored in closed containers detonated because of its confinement and the heat given off by a nearby fire. For a reason that was not specified, a stock of 80 tonnes of potassium chlorate detonated. Regarding this accident the authors make the assumption that the decomposition reaction of this compound would be the following ... 

Evaporation of a moist mixture of sodium phosphinate with a trace of sodium chlorate by slow heating caused a violent explosion. It was concluded that, once started, the decomposition of the phosphinate proceeds spontaneously [1]. Similar reactions have been reported with nitrates instead of chlorates. Such mixtures had previously been proposed as explosives [2], Interaction of iodine with the anhydrous salts is violently exothermic, causing ignition [3],... 

The halic acids may not be industrially important, but their salts certainly are. Sodium chlorate is produced in enormous quantities and used in processes in which its oxidizing strength makes it a versatile bleach. One such use is in making paper, and potassium chlorate is used as the oxidizing agent in matches. The decomposition of potassium chlorate was discussed in Chapter 13 in connection with the laboratory preparation of oxygen. 

The converse obviously applies to ammonium nitrate explosives, which must not contain any chlorates, since during storage a double exchange reaction may occur resulting in the formation of ammonium chlorate (p. 476, Vol. II), an unstable substance which decomposes spontaneously. A number of patents were taken out between 1880 and 1895, for explosives based on the use of ammonium chlorate or mixtures of ammonium nitrate with potassium or sodium chlorate. Many accidents which occurred through the spontaneous decomposition of these explosives proved the impossibility of using mixtures containing both chlorates and ammonium salts (Hantke [79]). 

Decomposition of sodium chlorate(i), catalysed by a cobalt(n) salt. 

Although most explosive incidents have involved mixtures of the chlorate with combustible materials, the exothermic decomposition of the chlorate to chloride and oxygen can accelerate to explosion if a sufficient quantity and powerful enough heating are involved. A case history of a fire-heated explosion of a store of 80 t of chlorate is given. The more stable sodium chlorate will also explode under similar... 

Electrolysis in this case only differs slightly from the sodium chlorate process. A sodium chloride solution or a mixed solution of sodium and potassium chloride is used as the electrolyte. The sodium chlorate in the electrolytically treated brine is converted to potassium salt by double decomposition with potassium... 

The chlorate is purified from the chloride by fractional crystallization. In Muspratt s method10 magnesium oxide suspended in water is substituted for sodium hydroxide, the solution being concentrated after treatment with chlorine, and sodium carbonate added to precipitate the magnesium for further use. The sodium chlorate crystallizes from the mother-liquor. The salt is also formed from potassium chlorate by double decomposition with substances such as sodium hydrogen tartrate and sodium silicofluoride, as well as by the electrolytic decomposition of sodium-chloride solution under certain conditions11 (p. 97). 

Manufacture. At first sodium chlorate is prepared by the electrolysis of industrial salt or the milk of lime process described in (2). The sodium chlorate is further electrolyzed to produce sodium perchlorate, and when potassium chloride is added to cause double decomposition, crude potassium perchlorate is obtained. This is recrystallized and crushed to powder. It is impossible to obtain potassium perchlorate by the direct electrolysis of potassium chlorate, because of the low solubility of potassium. perchlorate in water. 

For the industrial process a platinum anode and steel plate cathode are used, and a small amount of potassium bichromate is added to the electrolyte, The electric current efficiency is good when the concentration of the sodium chlorate is high, but it suddenly decreases as the concentration falls. The double decomposition which produces potassium perchlorate is as follows ... 

Sherwood et al. [25,26] have demonstrated the usefulness of X-ray topography in examining the microtextural displacements that occur during the initial stages of decomposition of single crystals of sodium chlorate. They showed that onset of decomposition is associated with centres of strain in the crystal, but, in contrast to... 

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