Hydrosulphurization

Oharaeter,—Like hydrosulphuric acid, it produces precipi tates in solutions of most of the heavy metals. 

Potassic seleniate is prepared by fbsing seleniam or metallio selenides with nitre. The acid is obtained by transforming the potassic salt into a plumbic salt, and subsequently deoompo-ring the latter with hydrosulphuric acid. 

By passing carbonic disulphide and hydrosulphuric acid, or carbonic disulphide and steam, over ignited copper —... 

The eSect of an excess of hydrogen sulphide has very little influence on the solubility of potassium hydrosulphide because, as V. Rothmund has indicated, this salt is too little ionized for the slightly dissociated hydrosulphuric acid to have an appreciable influence on the solubility. 

Test an aqueous hydrogen sulphide solution with litmus. What do you observe Find the dissociation constants of hydrosulphuric acid in a textbook. 

Hydrogen Sulphide, Sulphuretted Hydrogen or Hydrosulphuric Acid, HaS. 

Hydrogen Sulphide as an Acid. — In the anhydrous condition, whether as gas or liquid, hydrogen sulphide has no acidic properties. When moist or in aqueous solution, however, it behaves as a feeble acid, whence the occasional name hydrosulphuric acid. For the characteristic test with lead acetate paper or for the reddening of litmus paper, the presence of at least a little moisture is essential.3... 

Electrolysis of sulphurous acid causes anodic oxidation to sulphuric acid, whilst hydrosulphurous acid, H2S204, is produced by the reducing action of the current at the cathode 3 the former change may be rendered quantitative by the addition of a manganese salt 4 the hydrosulphurous acid may be accompanied by various of its decomposition products.5... 

Hydrosulphurous acid is also formed by the action of many metals on sulphurous acid 7 the crust of ferrous sulphite and hydrosulphite formed on the surface of metallic iron is of great protective value in the iron cylinders used for storing liquid sulphur dioxide, which generally contains traces of water.8... 

The composition of the oxide suggests that it may be an acid anhydride, but all attempts to convert it into hydrosulphurous acid, H2S204, or its derivatives, have been unsuccessful.7... 

Hydrosulphurous acid is also formed as an intermediate product in the reduction of sulphurous acid by hypophosphorous acid.8... 

The hydrosulphites are very liable to atmospheric oxidation, especially in the hydrated or moist condition in their preparation and preservation it is therefore desirable to exclude air. When exposed to the atmosphere a solution of a hydrosulphite first becomes yellow, probably due to the transient presence of free hydrosulphurous acid, but soon becomes colourless, the final product being sulphite.2 Much heat is evolved during this oxidation, as may readily be observed with the exposed moistened salt ... 

J. Tafel believed that the soln. of hydroxylamine sulphate in 50 per cent, sulphuric acid contained a salt NH2OH.H2S04, hydroxylamine hydrosulphate. A, Lidaff obtained this salt by the action of hydrosulphurous acid on potassium nitrite and E. Divers, by digesting the normal chloride with the calculated quantity of sulphuric acid, and evaporating in cold air. The prismatic crystals are very deliquescent. 

The method most commonly used, especially if it is desired to prepare anhydrous hydrocyanic acid, consists in decomposing a cyanide with an acid (hydrochloric, sulphuric, hydrosulphuric, carbonic, etc.). 

P. C. H. Mitchell reported on sulphide catalysts in Volume 1 and now gives a review of the extensive literature appearing from July 1976 to December 1979. He reports on the work on the characterization and the improvement by promoters and dopants of sulphide catalysts and he summarizes the new information about the nature of the active sites, about intermediates, and about mechanisms on such catalysts. He also refers to the increasing interest in other forms of hydroprocessing for which sulphide catalysts are being tested in addition to their main application in hydrosulphurization. D. L. Trimm in the final chapter deals with a complex and broad subject of carbon as a catalyst and the associated field of reactions of carbon with gases. His review is drawn from a wide range of journals and prefaced by an account of the nature of the carbon surfaces, their impurities, and the complexes found on them. 

The expansion in Chironomidae in August 2004 below the 30-metre mark - this is essentially deeper than described for October 2003 - we relate to the absence of hydrosulphuric infection at these depths at the end of summer. Apparently, the limiting factor on depth of the B. gr. noctivaga habitat in October 2003 was hydrogen sulphide. 

In the Western basin the maximum values of abundance corresponded to depths of about 8 m (11,360 ind. m, 32 g m ). At 13 m water depth B. gr. noctivaga number and biomass were essentially lower (1,950 ind. m 5.1 g m ). Atadepth of 38 m, under conditions of weak hydrosulphuric infection, larvae were absent. 

The aim of our study was to present the changes in properties of zeolites after alkali cation exchange and their influence on the hydrosulphurization of alcohols. 

No simple correlation between the electronegativity of zeolites and the conversion of methanol is observed (Fig.3). It is caused by two competitive processes which occurs during the reaction between ROH and H2S i.e. transformation of alcohols towards hydrocarbons (increasing with the increase of the zeolite electronegativity) and hydrosulphurization of alcohols towards thiols (decreasing with the increase of the electronegativity). ... 

In solution the acidic properties of hydrogen sulphide appear and under the name of hydrosulphuric acid the compound may be compared with hydrochloric acid. 

The protochloride of antimony is easily prepared by boiling in hydrochloric acid the powdered native sulphide of antimony. When the disengagement of hydrosulphuric acid begins to be slow, the whole is boiled for a few minutes. After cooling, the clear liquid Is decanted. 

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