Other metal sulphates

Relatively little kinetic information is available concerning the decompositions of other metal sulphates. Decomposition of the lanthanide sulphates [800,801] proceeds to completion in two stages. 

Thermal analyses of some divalent metal selenates and their hydrates have been reported [802]. 

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Kinetic data available for the reactions of other metal sulphates refer to reaction conditions closer to those of actual pyrometallurgical processes [790]. 

In fresh solutions of the green sulphate, the latter has the power of masking the sulphate ion in other metallic sulphates to the extent of several hundred molecules for each molecule of the green salt present, the actual amount depending on the age of the green solution, its concentration and degree of acifity. ... 

This paper reports the results of a dialysis study using aqueous solutions 1 M in ammonium sulphate and 0.05 M in various other metal sulphates. The sparse results for the nickel system are interpreted in terms of formation of Nij(S04)4". There are insufficient details to derive useful complexation constants from the data. Also see [41KIS/ACS]. 

Even small traces of certain corrosion stimulants, notably soluble chlorides and sulphates, can maintain a continuing corrosion process under a paint film because the salts accelerate the initial dissolution of ferrous iron (and other metal ions) but are not immobilised in the hydrated oxide corrosion products. Filiform corrosion is the most spectacular example of this phenomenon, but progressive spread, preceded by blistering, is also observed from scratches or other breaks in a coating, for example during salt spray tests. 

Early discussions, by Tammann and by Hedvall, considered the possible existence of a common characteristic (approximate) temperature for a solid at which chemical interactions with other reactants became detectable. For example [111], such a characteristic temperature for CaO, measured in various reactions with CuS04, Co3(P04)2, MgC03, and MnSi03, was found to be 788—838 K. Similarly, the onset of reaction of BaO with the sulphates of Mg, Ca, Sr, Co, Cu, and Zn occurred between 601 and 645 K. In the latter example, it has been shown that the fusion of Ba(OH)2 (an impurity not easily excluded from BaO) could contribute to the initiation of reaction. Eutectic formation during the reactions of BaCl2 with alkali metal sulphates... 

Mercury and silver have long been known to have antibacterial properties and preparations of these metals were among the earliest used antiseptics, but have been replaced by less toxic compounds. Other metals such as zinc, copper, aluminium and tin have weak antibacterial properties but are used in medicine for other functions, e.g. aluminium acetate and zinc sulphate are employed as astringents. 

Many platinum analogs, and analogs based on other metal centres, have been prepared and evaluated. Carboplatin (7.89, cA-diammine(l,l cyclobutanedicarboxalato)platinum) has markedly reduced gastrointestinal and renal toxicity in comparison with cisplatin. It is prepared by the treatment of cA-Pt(NH3)2l2 with silver sulphate, followed by the barium salt of 1,1-cyclobutanedicarboxylic acid. 

On the other hand, sulphates of tervalent metals dissociate easily. The old process for the preparation of H2S04 was based on the dissociation of ferric sulphate, the SOs being absorbed in moderately dilute sulphuric acid. In this manner fuming sulphuric, or Nord-hausen, acid can be prepared. 

Basic sulphates are obtained when the normal sulphates of antimony, bismuth and mercury are treated with water, sulphuric acid being produced simultaneously. These salts are insoluble in water. Many other metals, for example copper,6 aluminium 8 and tin,7 yield precipitates of basic sulphates on the addition of alkali to aqueous solutions of their normal sulphates. 

The Tetrathionates.—These are generally soluble in water and can be caused to crystallise from solution by the addition of alcohol. When heated in solution the alkali salts decompose into trithionate and sulphur further change may also give rise to pentathionate, sulphate and sulphite. Aqueous solutions are less stable in the presence of thiosulphate.5 The salts of the other metals, for example barium or copper, are much less stable, the former readily forming thiosulphate 6 and the latter sulphide.2... 

B. Wet Processes.—These vary considerably in detail according to the nature and amount of constituents other than vanadium in the ore. An outline of the operations involved in the case of patronite is as follows The ore is roasted with common salt or sodium carbonate and then extracted either (a) with water to give an alkaline solution of sodium vanadate and soluble vanadates of other metals, any lead, zinc, copper, etc., being left in the residue or (b) with sulphuric acid to produce a solution of vanadyl sulphate. Acid extraction is usually employed when the vanadium content of the material is low. The alkaline extract from (a) is treated with excess of sodium carbonate in order to precipitate calcium and aluminium, after removal of which,... 

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... 

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