Potassium perchlorate, solubility

Examples of Values of L and AF°. As a first example we may evaluate both L and AF° for a moderately soluble salt in aqueous solution. At 25° a saturated solution of potassium perchlorate has a concentration of 0.148 mole of KCIO4 in a 1000 grams of water that is to say, y+ = y = 0.148/55.5. The activity coefficient in the saturated solution has been taken1 to be 0.70 + 0.05. Using this value, we can estimate the work required to take a pair of ions from the crystal surface to mutually distant points, when the crystal is in contact with pure solvent at 25°C ... 

A. A. Noyes and co-workers measured the depressed solubility of potassium perchlorate in aq. soln. of potassium chloride and potassium sulphate. 

Metallic perchlorates are soluble in water, except ihat potassium perchlorate is slightly soluble. Potassium perchlorate is, however, insoluble... 

Chlorate. Potassium chlorate, [CAS 3811-04-9], chlorate of potash, KCIO, white solid, soluble, mp about 350°C, powerful oxidizing agent, and consequently a fire hazard with dry organic materials, such as clothes, and with sulfur upon heating oxygen is liberated and the residue is potassium chloride formed by electrolysis of potassium chloride solution under proper conditions, Used (l)m matches, (2) in pyrotechnics, (3) as disinfectant, (4) as a source of oxygen upon heating, (Hazardous Use of potassium perchlorate is recommended instead )... 

Perchlorate. Potassium perchlorate. [CAS 7778-74-7]. KCKU. white solid, very slightly soluble, mp 610°C, but above 400VC decomposes with evolution of oxygen gas and formation of potassium chloride residue formed (1) by electrolysis of potassium chlorate under proper conditions. (2) by heating potassium chlorate at 48(UC and then fractional crystallization. Used (1) as a convenient and safe (preferred to use of potassium chlorate) method of preparing oxygen by heating, (2) 111 the determination of potassium in soluble salt solution. 

For most potentiometric measurements, either the saturated calomel reference electrode or the silver/silver chloride reference electrode are used. These electrodes can be made compact, are easily produced, and provide reference potentials that do not vary more than a few mV. The silver/silver chloride electrode also finds application in non-aqueous solutions, although some solvents cause the silver chloride film to become soluble. Some experiments have utilised reference electrodes in non-aqueous solvents that are based on zinc or silver couples. From our own experience, aqueous reference electrodes are as convenient for non-aqueous systems as are any of the prototypes that have been developed to date. When there is a need to exclude water rigorously, double-salt bridges (aqueous/non-aqueous) are a convenient solution. This is true even though they involve a liquid junction between the aqueous electrolyte system and the non-aqueous solvent system of the sample solution. The use of conventional reference electrodes does cause some difficulties if the electrolyte of the reference electrode is insoluble in the sample solution. Hence, the use of a calomel electrode saturated with potassium chloride in conjunction with a sample solution that contains perchlorate ion can cause dramatic measurements due to the precipitation of potassium perchlorate at the junction. Such difficulties normally can be eliminated by using a double junction that inserts another inert electrolyte solution between the reference electrode and the sample solution (e.g., a sodium chloride solution). 

The chlorates, like the nitrates, are all readily soluble in water lead and silver chlorites, like the corresponding nitrites, are sparingly soluble salts and lead perchlorate is the only salt which does not easily dissolve. As already mentioned, chloric acid is readily decomposed when its aqueous solution is warmed chlorous acid is still less stable but perchloric acid, which may be prepared by distilling together potassium perchlorate with concentrated sulphuric acid, is relatively stable, seeing that it can be distilled without decomposition. It is an oily liquid, with acid taste it is apt to explode when brought into contact... 

Until recently, the most popular reference half-cell for potentiometric titrations, polarography, and even kinetic studies has been the saturated aqueous calomel electrode (SCE), connected by means of a nonaqueous salt bridge (e.g., Et4NC104) to the electrolyte under study. The choice of this particular bridge electrolyte in conjunction with the SCE is not a good one because potassium perchlorate and potassium chloride have a limited solubility in many aprotic solvents. The junction is readily clogged, which leads to erratic junction potentials. For these practical reasons, a calomel or silver-silver chloride reference electrode with an aqueous lithium chloride or quaternary ammonium chloride fill solution is preferable if an aqueous electrode is used. 

The second reaction is accelerated by catalyzers, such as manganese dioxide or ferric oxide, or in fact any material with a rough surface. Too high a temperature also causes reaction (2) principally to take place. On the other hand, if the temperature is maintained at the right point, the salt is free from dirt, and the inside of the crucible is perfectly clean and free from roughness, the decomposition proceeds mainly according to reaction (1). Potassium perchlorate is very sparingly soluble in cold water and may be separated from potassium chloride and any undecomposed potassium chlorate by crystallization. 

Perchlorates are most stable of all the salts of oxy-acids of chlorine. Potassium perchlorate is commercially the most important salt of perchloric acid. This salt is a colourless powder having the formula KC104, only sparingly soluble in water. If heated to high temperatures, it liberates oxygen. 

For this reason the time, of heating must be watched carefully. After the reaction mass has cooled it is leached with cold water in order to separate the easily soluble potassium chloride from the sparingly soluble potassium perchlorate. Eventually the potassium perchlorate is recrystallized from a hot water solution. The described method is commercialy unimportant as one quarter of the chlorate at least is converted into worthless potassium chloride (see equation XVIII-l). 

Potassium perchlorate forms colorless to white crystals, or white crystalline powder, or granules. The crystals begin to decompose when heated to 400 Celsius into oxygen and potassium chloride. Potassium perchlorate is sensitive to concussion, and forms explosive mixtures with combustible materials such as sulfur and charcoal. The crystals have a low solubility in water (1 gram per 65 milliliters of water) at room temperature, but the crystals are somewhat soluble in boiling water (1 gram in 15 milliliters). Potassium perchlorate is insoluble in the usual solvents. 

Potassium perchlorate is insoluble in alcohol but soluble in water. It is prepared by reacting a soluble potassium salt with sodium perchlorate or perchloric acid. It is employed in pyrotechnics. 

Anhydrous magnesium perchlorate, Mg(C104)2, and barium perchlorate, Ba(C104)2, are used as drying agents (desiccants). These salts have a very strong attraction for water. Nearly all of the perchlorates are highly soluble in water potassium perchlorate is exceptional for its low solubility, 0.75 g/100 g at 0" C. 

M. M. P. Muir ° has measured the solubility of potassium perchlorate he found that at 0°, 100 grms. of water dissolved 0 71 grms. of potassium perchlorate at 25°, 1 96... 

Sodium chlorate contains more oxygen than potassium chlorate, but has the disadvantage of being hygroscopic. Neither salt ought to be used in mixtures which contain ammonium nitrate or ammonium perchlorate, for double decomposiUon mi t occur with the formation of dangerous ammonium chlorate. Potassium chlorate is one of the chlorates least soluble in water, potassium perchlorate one of the least soluble of the perchlorates. The latter salt is practically insoluble in alcohol. The perchlorates are in-... 

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. 

In this case the potassium perchlorate crystallizes out- as fine crystals because of its low solubility in water. 

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