Persulphate, ammonium potassium

Concentrated acid solutions of vanadium pentoxide are reduced to the tetravalent state by hydrogen peroxide, the peroxides of sodium, barium, magnesium, and by persulphates of potassium and ammonium.4 Acid solutions of vanadium pentoxide give rise to pervanadic acid with hydrogen peroxide. 

Persulphates of potassium and ammonium are produced by passing a current of electricity through concentrated solutions of the sulphates in water. The persulphate is sparingly soluble, and deposits in white crystals. The formula appears to be M2S2Os (M = monad metal). The acid has bleaching powers, and gradually decomposes into sulphuric acid and ozone. 

Persulphates (inorganic diperoxysulphates of ammonium, potassium, and sodium, and triple salt potassium monopersulphate) are used as initiators in the polymer and fibre industry, as well as other applications in other industrial sectors. 

A number of etchants are in use, depending upon the nature of the process and, to an extent, personal preference or tradition. These include (1) ammonium persulphate (2) sodium persulphate (3) potassium peroxysulphate (4) cupric chloride (5) FeClj (6) H2Cr04 (7) ammoniacal chlorite and (8) hydrogen peroxide/sulphuric acid. 

Procedure. Weigh out accurately an amount of the salt which will contain about 0.25 g of chromium, and dissolve it in 50 mL distilled water. Add 20 mL of ca 0.1 M silver nitrate solution, followed by 50 mL of a 10 per cent solution of ammonium or potassium persulphate. Boil the liquid gently for 20 minutes. Cool, and dilute to 250 mL in a graduated flask. Remove 50 mL of the solution with a pipette, add 50 mL of a 0.1 M ammonium iron(II) sulphate solution (Section 10.97, Procedure A), 200 mL of 1M sulphuric acid, and 0.5 mL of /V-phenylanthranilic acid indicator. Titrate the excess of the iron(II) salt with standard 0.02M potassium dichromate until the colour changes from green to violet-red. 

An account of a serious warehouse explosion (15 dead, 141 injured). The two principal detonations were mostly due to ammonium nitrate, of which some hundred tonnes had been present, but the initiating fire was first observed in ammonium persulfate. This had been promiscuously stored alongside potassium permanganate, matches, potassium nitrate and sodium sulphide (or possibly sulphite), inter alia. None of these would improve the safety of ammonium persulfate. It was shown that the persulphate gives an immediate exothermic reaction with the sulphide. This was ascribed as the ultimate initiation. It was concluded that oxidants and... 

Electrometric Methods have been applied for the estimation of vanadium alone and alloyed with other metals, e.g. iron, chromium, uranium. The reduced solution is either gradually oxidised by means of a suitable oxidising agent (potassium permanganate, ammonium persulphate, nitric acid), or the vanadate solution is gradually reduced with ferrous sulphate solution the changes in the E.M.F. of a suitable cell indicate the end point.8... 

Cold saturated aqueous potassium per sulphate solution or i% aqueous ammonium persulphate.1... 

Saturated, cold aqueous solution of potassium persulphate or 1% aqueous ammonium persulphate (see note on p. 472). 

In reoxidation by means of the air, the reduced sample may be exposed to ammonia vapour, which in many cases accelerates the reoxidation. If the colour does not reappear under these conditions, treatment with a cold, saturated potassium persulphate solution or with 1% ammonium persulphate solution is tried in accordance with the indications given for woollen fabrics (see p. 473). 

H. Stamm also measured the solubilities of the salts of the alkalies in liquid ammonia —potassium hydroxide, nitrate, sulphate, chromate, oxalate, perchlorate, persulphate, chloride, bromide, iodide, carbonate, and chlorate rubidium chloride, bromide, and sulphate esesium chloride, iodide, carbonate, and sulphate lithium chloride and sulphate sodium phosphate, phosphite, hypophosphite, fluoride, chloride, iodide, bromate, perchlorate, periodate, hyponitrire, nitrite, nitrate, azide, dithionate, chromate, carbonate, oxalate, benzoate, phtnalate, isophthalate ammonium, chloride, chlorate, bromide, iodide, perchlorate, sulphate, sulphite, chromate, molybdate, nitrate, dithionate, thiosulphate, persulphate, thiocyanate, phosphate, phosphite, hypophosphite, arsenate, arsenite, amidosulphonate, ferrocyanide, carbonate, benzoate, methionate, phenylacetate, picrate, salicylate, phenylpropionate, benzoldisulphonate, benzolsulphonate, phthalate, trimesmate, mellitate, aliphatic dicarboxylates, tartrate, fumarate, and maleinate and phenol. 

The existence of highly oxidised salts of sulphuric acid was first demonstrated by H. Marshall1 when investigating the result of electrolysis of solutions of potassium sulphate in well-cooled sulphuric acid. He succeeded in preparing potassium and ammonium persulphates, and he ascribed the formula M2Sj08 to these compounds. 

It was then shown by M. G. Levi1 that the yield is not diminished by allowing the temperature to rise as high as 30° C., and is almost independent of the cathode material used, but he found that a new smooth platinum anode gives a better yield than an old one which has a somewhat rough surface. A patent process of 1904 claimed the use of an undivided cell with the addition of hydrofluoric acid, under which circumstances E. Miiller2 had shown that the yield of potassium persulphate was equal to that of the ammonium salt. This rendered possible the direct production of the potassium salt without relying on the intermediate formation of ammonium persulphate and subsequent decomposition with potassium chloride. 

Percarbonate of potassium was first prepared by E. J. Oonstam and A V. Hansen2 in 1896 by employing a divided cell, similar to that used for preparing ammonium persulphate, fitted with platinum electrodes. 

This method, which was worked out by the Electrochemische Werke in Munich, is similar to the Loewenstein method. In the first stage of the electrolytic process which starts with ammonium hydrogen sulphate ammonium persulphate solution is obtained. When reacting with potassium hydrogen sulphate, this intermediary product is converted to a slightly soluble potassium per-... 

Conversion is oarried out in such a manner that only about a half of the ammonium porsulphate present is converted to the slightly soluble potassium salt, the remainder is recycled into the electrolytic process. (Not more than a half of the persulphate should be converted, otherwise too much potassium salt would pass into the solution. During electrolysis this would be separated in the form of a poorly soluble potassium persulphate and obstruct the process). Potassium persulphate crystals are separated from the solution by stainless steel centrifuges. 

A peroxide, probably Ag203, is stated to be produced by anodic oxidation of silver in acid solution.4 When solutions of sodium or potassium persulphate react with silver or silver nitrate, a peroxide with a higher percentage of oxygen than Ag2Oa is produced, the process being attended by catalytic decomposition of the persulphate with formation of the acid sulphate. Ammonium persulphate does not yield a peroxide, but the ammonium radical becomes oxidized to nitric acid.6... 

Rogers s Method A This method is based on the decomposition of the arsenical compound with nitric acid and ammonium persulphate and the titration of the iodine liberated on addition of potassium iodide. 

Oxidation of manganese(D) by powerful oxidants in acidic solutions to yield violet MnOT ions constitutes the basis of this method [11,12]. The reactions with potassium periodate and ammonium persulphate, two popular reagents for the oxidation of Mn ", are ... 

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