Oxides of potassium

The iodometric analysis method for CIO2 and its coproducts is based on the pH-dependant oxidation of potassium iodide to selectively distinguish the various oxychlorine species from each other (42,89). The reactions of the oxidizer species with iodide at various pH buffered conditions ate... 

The oxidation of potassium thiocyanate by AuBrJ is first-order in oxidant and the pH dependence indicates that it is also first-order in thiocyanate ion, which is oxidised much faster than HCNS . The activation parameters are E = 6.4+0.4 kcal.mole and A5 = 26 + 2 eu. 

Weissler A, Herbert Cooper W, Snyder Stuart (1950) Chemical effects of ultrasonic waves oxidation of potassium iodide solution by carbon tetrachloride. J Am Chem Soc 72 1769-1775... 

Potassium ferricyanide is prepared by oxidation of potassium ferrocyanide, K4Fe(CN)6. Thus, when chlorine is passed through an aqueous solution of potassium ferrocyanide, the ferricyanide separates as crystals. 

Potassium periodate can be prepared by oxidation of potassium iodate with a powerful oxidizing agent such as potassium permanganate, chlorine or bromine in basic solution ... 

Oxidation of Potassium Peroxide. Determination of Potassium Superoxide. Potassium peroxide was prepared by the addition of a tert-butyl alcohol solution of 90% hydrogen peroxide to potassium tert-butoxide in DMSO or tert-butyl alcohol. Oxygen absorption was followed in the standard manner (20). Analysis of solid precipitates for potassium superoxide followed exactly the method of Seyb and Kleinberg (23). Potassium superoxide formed in the oxidation of benzhydrol was determined in a 15-ml. aliquot of the oxidation solution. To this aliquot 10 ml. of diethyl phthlate was added to prevent freezing of the solution. The mixture was cooled to 0°C., and 10 ml. of acetic acid-diethyl phthlate (4 to 1) added over a period of 30 minutes with stirring. The volume of the evolved oxygen was measured. 

An important aspect of the Haber process is the use of several catalysts in the reaction. A major problem in Haber s attempt to synthesis ammonia was identification of suitable catalysts. Haber discovered that iron oxides worked as the primary catalysts in combination with smaller amounts of oxides of potassium and aluminum. 

A similar reaction of great commercial importance is the synthesis of ammonia from the diatomic elements. The catalysts that are used commercially in this reaction are mixtures of iron and iron oxide with the oxides of potassium and aluminum. Indicating the adsorbed species by the subscript (or), the mechanism for the surface-catalyzed synthesis of ammonia is thought to involve the steps... 

A. V. Harcourt21 found that while the tetroxide, K204, is the end-product of the oxidation of potassium, the dioxide, Na202, is the end-product of the oxidation of sodium. A. V. Harcourt was unable to prepare an intermediate oxide, K2O3, of definite composition. He noticed that the oxidation occurs in two stages when... 

The tetroxides of the alkali metals.—The highest oxide formed by lithium is the dioxide, and with sodium the trioxide potassium, rubidium, and csesium form tetroxides. A. V. Harcourt38 showed that the indications of the higher oxides of potassium observed by J. L. Gay Lussac and L. J. Thenard, and by H. Davy, about 1810, probably represented the formation of potassium tetroxide. The... 

Sodium and potassium oxides cannot be conveniently made by calcining the corresponding carbonate and digesting the residue with water as is possible in the case of calcium oxide, because the two alkali carbonates do not decompose so readily on ignition as calcium carbonate. Lithium carbonate, however, is more closely related to calcium carbonate than the other alkali carbonates. The preparation of the oxides of potassium and sodium is rather difficult and expensive. 

The temp, coeff. for normal soln. between 18° and 26° is 0 0236. W. Hittorf measured the transport numbers of the ions of the sodium salt. A. Rius y Miro found that the electrolytic oxidation of potassium hydrophosphate probably occurs in two stages K2HPQ4->K4P20g->2K2HP05. 

Oxides of Potassium.—By combining with oxygon, this metal forms three compounds—rah oxide, KjO protoxide, KO and peroxide, KOa, The first named is produced when potassium is heated with a limited supply of air in a close vessel, ox when it is heated with the higher oxides. The protoxide is obtained when an equivalent of potassium is allowed to act upon odo of water, in a vessel from which the air is carefully excluded. 

The thiocyanates are generally soluble in water, the exceptions being those of lead, silver, mercury and copper. Most of them dissolve also in alcohol and ether. Aqueous solutions of the alkali thiocyanates undergo atmospheric oxidation under the influence of sunlight with solutions of medium concentration this change takes place rapidly, with separation of a yellow, amorphous precipitate consisting of pseudocyanogen sulphide, (CNS)3 (cf. p. 236). The concentration of thiocyanate most favourable to the separation of this sulphide is about 50 per cent, in summer and 10 per cent, in winter. In addition to this substance the products of the photochemical oxidation of potassium thiocyanate include hydrocyanic acid, sulphate, carbon dioxide, ammonia and ammonium salts ... 

Bassam Z. Shakhashiri, "Hydrogen Peroxide Iodine Clock Oxidation of Potassium Iodide by Hydrogen Peroxide," Chemical Demonstrations, A Handbook for Teachers of Chemistry, Vol. 4 (The University of Wisconsin Press, Madison, 1992), pp. 37-43. 

The ash is almost completely soluble in hydrochloric acid the insoluble part, consisting of sand and earth, should not exceed 0-3% of the flour. About 50% of the ash is phosphoric anhydride, the remainder being oxides of potassium, calcium, magnesium, sodium and iron, with traces of silica and chlorine. Lead, copper, zinc and alum should be absent. 

Gupta R, Wallace HC. Sonochemical reactions at 640 kHz using an efficient reactor. Oxidation of potassium iodide. Ultrason Sonochem 1997 4 289-293. 

Estimation.—Ozone in small quantities is usually estimated by the oxidation of potassium iodide, the gas being passed through a neutral or alkaline solution of the salt. With an alkaline solution there is less danger of the loss of iodine, and in any case the solution must not be acidified until after the ozone treatment or the results will be high. The extent of the oxidation is determined by acidifying and then titrating the liberated iodine with thiosulphate in the usual way. ... 

Oxidation of potassium platinocyanide with lead peroxide, acidulated with dilute sulphuric acid, yields a product containing the S04 group,1 of formula3 a K2Pt(CN)4.K2Pt(CN)4.S04, where x is probably 9 but again no platinicyanide is formed. 

Potassium monoxide, K20.—The monoxide is formed by incomplete oxidation of potassium by dry oxygen at reduced pressure, and removal of the excess of metal by distillation in vacuum.1 The product forms microscopic octahedra, which become pale-yellow at 200° C., and have a density of 2-32 at 0° C. Above 400° C. in vacuum it is decomposed into the metal and the peroxide. The heat of formation of the monoxide from its elements is 86-80 Cal.2 It is reduced by hydrogen to the hydride and hydroxide. With water it reacts energetically to form the hydroxide, the heat of solution being 75-0 Cal.3 It also combines with fluorine, chlorine, and iodine. The heat of formation from the elements is 86-8 Cal.3... 

Rashid and Kalvoda examined this reaction using cyclic voltammetry by measuring the current enhancement for the electro-oxidation of potassium ferricyanide on addition of the amine. Using working curves derived by Nicholson and Shain (1964) relating the ratio of the peak current measured in the presence and absence (i.e. the diffusion-controlled peak current for oxidation of ferricyanide) of the amine to the parameter kfRTInFvioT an EC mechanism, the kinetic parameter, kf, could be calculated. 

Generation of positive-like halogen species in situ has been realized by the oxidation of halide salts with m-chloropeibenzcnc acid (M BA). The procedure can be used for haloetherification and lactoni-zation (equation 28). Oxidation of potassium bromide with MCPBA in the presence of 18-crown-6 (10 mol %) produces m-chlorobenzoylhypobromite, which adds across the double bond to furnish trans-, 2-bromocarboxylates (55 equation 29). ... 

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