Potassium chlorates

Potassium chlorate, KCIO3, is a colorless, crystalline material with a melting point of 640 K. Just above the melting-point temperature, it decomposes to produce oxygen molecules according to  

Potassium chlorate is used as an oxidizer of chlorate explosives, primers, and matchheads. Mixtures of potassium chlorate and fuel components detonate relatively easily. 

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 

After the raw chlorate has been washed, the wash water, which is rich in sodium chloride, is boiled down in an evaporator and the common salt precipitated is separated in a suction filter and reused. In this way, a portion of the sodium chloride is removed from the electrolytic liquor. Failing this the content of NaCl would continually increase, as the potassium chloride used always contains some sodium salt. Hot mother liquor is cooled in a vacuum cooler, where further portions of potassium chlorate are crystallized. 

Read the discussion of the hydrolysis of bromine in the preceding preparation. About one-third of the chlorine in chlorine water is hydrolyzed. The bleaching power of chlorine is due directly to the oxidizing action of the hypochlorous acid produced by the hydrolysis. The formation of chlorate in this preparation is also a result of the oxidizing action of hypochlorous add. 

In the action of chlorine with an alkali hydroxide, six equivalents of the latter must react in order to produce one equivalent of alkali chlorate. To economize in potassium hydroxide, which is more expensive than sodium hydroxide, we shall use one equivalent only of the former and five equivalents of the latter. The five equivalents of sodium chloride which could be recovered as a byproduct is not of great value, and we shall discard it in this preparation. 

Apparatus 500-cc. flask with 2-hole rubber stopper. 

A product of 15 grams is to be regarded as satisfactory. The mother liquors should all have been saved to work over again if the recrystallizations have not been skilfully enough carried out the first time. 

Tabulate the solubilities at high and low temperatures of the salts concerned, and arrange a flow sheet of the method to be followed if the mother liquors are worked over. 

EXPLOSIVE WHEN MIXED WITH COMBUSTIBLE MATERIAL 

Powerful oxidizing agent. Forms explosive mixtures with combustible materials. Extinguish with water.2 

Ammonia or Ammonium Sulfate. Vigorous reaction with high concentrations of NH3 on heating, a mixture with (NH4)2S04 decomposes with incandescence.3 

Hydrocarbons. Violent explosions occur on mixing powdered potassium chlorate with hydrocarbons.4 

Hydrogen Iodide. Molten potassium chlorate ignites HI gas.5 

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Liquid chlorine dioxide, ClOj, boils at 284 K to give an orange-yellow gas. A very reactive compound, it decomposes readily and violently into its constituents. It is a powerful oxidising agent which has recently found favour as a commercial oxidising agent and as a bleach for wood pulp and flour. In addition, it is used in water sterilisation where, unlike chlorine, it does not produce an unpleasant taste. It is produced when potassium chlorate(V) is treated with concentrated sulphuric acid, the reaction being essentially a disproportionation of chloric(V) acid ... 

The reaction usually proceeds with explosive violence and a better method of preparation is to heat, gently, moist crystals of ethane-dioic acid (oxalic acid) and potassium chlorate(V) ... 

Unexpectedly we find that the bromate(V) ion in acid solution (i.e. effectively bromic(V) acid) is a more powerful oxidising agent than the chlorate(V) ion, CIO3. The halates(V) are thermally unstable and can evolve oxygen as one of the decomposition products. Potassium chlorate(V), when heated, first melts, then resolidifies due to the formation of potassium chlorate(VII) (perchlorate) ... 

The decomposition of potassium chlorate(V) is catalysed by manganese(IV) oxide, Mn02, and oxygen is evolved on heating the mixture below the melting point of the chlorate(V). 

Chloric(VII) acid is prepared by carefully distilling potassium chlorate(VII) with concentrated sulphuric acid under reduced pressure ... 

It catalyses the decomposition of potassium chlorate(V). Mixed with zinc oxide, it is used as a catalyst in the manufacture of methanol. It is used as a pigment, being very resistant to weathering. 

Alizarin. Dissolve successively in 75 ml. of water 6 g. of potassium chlorate, 20 g. of sodium anthraquinone- p-sulphonate and 75 g. of sodium hydroxide. Transfer the mixture to a 500 ml. autoclave (compare Section VI,4) and heat for 20 hours at 170°. After coohng, scrape out... 

In the laboratory it can be prepared by the electrolysis of water or by heating potassium chlorate with manganese dioxide as a catalyst. 

Copper or iron oxides Hot hydrochloric acid plus potassium chlorate. 

Sulfur dioxide Halogens, metal oxides, polymeric tubing, potassium chlorate, sodium hydride... 

Titanium Aluminum, boron trifluoride, carbon dioxide, CuO, halocarbons, halogens, PbO, nitric acid, potassium chlorate, potassium nitrate, potassium permanganate, steam at high temperatures, water... 

Potassium iodate [7758-05-6] KIO, mol wt 214.02, 59.30% I, forms white, odorless crystals or a crystalline powder. It has a density 3.98 g/mL and mp of 560°C with partial decomposition. Potassium iodate is rapidly formed when potassium iodide is fused with potassium chlorate, bromate, or perchlorate. The solubihty in water is 9.16 g/100 g H2O at 25°C and 32.2 g/100 g H2O at 100°C. KIO is extensively used as an oxidizing agent in analytical chemistry and as amaturing agent and dough conditioner (see Bakery processes and leavening agents). 

Other early match-like devices were based on the property of various combustible substances mixed with potassium chlorate to ignite when moistened with strong acid. More important was the property of chlorates to form mixtures with combustibles of low ignition point which were ignited by friction (John Walker, 1827). However, such matches containing essentially potassium chlorate, antimony sulfide, and later sulfur (lucifers), mbbed within a fold of glass powder-coated paper, were hard to initiate and unreHable. 

Because small children may suck on matches, the question of toxicity is often raised and the lingering, vague, though unwarranted idea of phosphoms poisoning may cause concern to laymen and even to physicians. Potassium chlorate is the only active material that can be extracted in more than traces from a match head and only 9 mg are contained in one head. This, even multiphed by the content of a whole book, is far below any toxic amount (19) for even a small child. No poisonous properties whatsoever can be imputed to the striking strip. SAW matches are similarly harmless but, because of their easy flammabihty, they should be entirely kept out of a household with smaller children. The same warning may apply to all wooden matches. 

When soHd potassium chlorate is carefully heated, it can be transformed into perchlorate thermally ... 

Pyrotechnic mixtures may also contain additional components that are added to modify the bum rate, enhance the pyrotechnic effect, or serve as a binder to maintain the homogeneity of the blended mixture and provide mechanical strength when the composition is pressed or consoHdated into a tube or other container. These additional components may also function as oxidizers or fuels in the composition, and it can be anticipated that the heat output, bum rate, and ignition sensitivity may all be affected by the addition of another component to a pyrotechnic composition. An example of an additional component is the use of a catalyst, such as iron oxide, to enhance the decomposition rate of ammonium perchlorate. Diatomaceous earth or coarse sawdust may be used to slow up the bum rate of a composition, or magnesium carbonate (an acid neutralizer) may be added to help stabilize mixtures that contain an acid-sensitive component such as potassium chlorate. Binders include such materials as dextrin (partially hydrolyzed starch), various gums, and assorted polymers such as poly(vinyl alcohol), epoxies, and polyesters. Polybutadiene mbber binders are widely used as fuels and binders in the soHd propellant industry. The production of colored flames is enhanced by the presence of chlorine atoms in the pyrotechnic flame, so chlorine donors such as poly(vinyl chloride) or chlorinated mbber are often added to color-producing compositions, where they also serve as fuels. 

Various sulfides of the halogens are formed by direct combination of sulfur with fluorine, bromine, and chlorine. No evident reaction occurs with iodine instead, the elements remain as components of a mixture. Mixtures of sulfur and potassium chlorate, or sulfur and powdered zinc, are highly explosive. 

Quantitatively, sulfur in a free or combined state is generally determined by oxidizing it to a soluble sulfate, by fusion with an alkaH carbonate if necessary, and precipitating it as insoluble barium sulfate. Oxidation can be effected with such agents as concentrated or fuming nitric acid, bromine, sodium peroxide, potassium nitrate, or potassium chlorate. Free sulfur is normally determined by solution in carbon disulfide, the latter being distilled from the extract. This method is not useful if the sample contains polymeric sulfur. 

Several common acid treatments for sample decomposition include the use of concentrated nitric acid, aqua regia, nitric—sulfuric acids, and nitric perchloric acids. Perchloric acid is an effective oxidant, but its use is ha2ardous and requkes great care. Addition of potassium chlorate with nitric acid also assists in dissolving any carbonaceous matter. 

Yokagawa Electric Works has developed a thermometer based on the nuclear quadmpole resonance of potassium chlorate, usable over the range from —184 to 125°C. This thermometer makes use of the fundamental properties of the absorption frequency of the Cl nucleus, and its caUbration is itself a constant of nature. 

Physical Properties. The physical properties of sodium chlorate [7775-09-9] and potassium chlorate [3811-04-9], KCIO, are summarised ia Table 1 (21). The solubiHties of these chlorates ia water are given ia Figure 2 (22—26). 

Fig. 2. Aqueous solubiHty of A, sodium chlorate and B, potassium chlorate where bp represents 122°C, the boiling point of a saturated solution of sodium...

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