Sulphur dioxide solubility

On the basis of the sulphur dioxide solubility in water it is assumed that this gas will pass fairly rapidly through the upper respiratory ways. Experiments of this type were also performed on larger animals (dogs and rabbits) as well as on man [6]. The use of S02 made it possible to trace the sulphur dioxide absorption in doses of 0.05 to 700 ppm. It was found that at concentrations of 20 ppm, 90 to 98% of sulphur dioxide did not penetrate through the upper respiratory ways of rabbits. These results were in agreement with those in dogs and man. At concentrations below 1 ppm, only 2 to 10% of sulphur dioxide did not penetrate beyond the trachea. The results of experiments with S02 demonstrated that the sulphur dioxide inhaled is transported very rapidly into the whole body [7]. The sulphur dioxide inhaled is removed only slowly through the respiratory tract. The radioactivity in the respiratory tract can be detected at most for one week after the exposure. A portion of is incorporated into proteins [8]. 

Barium sulphite is soluble in dilute hydrochloric acid unlike barium sulphate which is insoluble. Hence this reaction, and the evolution of sulphur dioxide on addition of an acid, distinguishes a sulphite from a sulphate. 

For example, sulphur dioxide is highly water soluble and tends to be absorbed in the airways above the larynx. Responses at various concentrations are summarized in Table 5.3. However, in the presence of particulate catalysts and sunlight, conversion to sulphur trioxide occurs and the in itant response is much more severe. 

Atmospheric exposure trials, carried out in Cambridge, established the fact that when rusty specimens were painted in the summer, their condition, after some years exposure, was very much better than that of similar specimens painted in the winter It was found that steel weathered in Cambridge carried spots of ferrous sulphate, deeply imbedded in the rust, and that the quantity of ferrous sulphate/unit area was very much greater in the winter than in the summer this seasonal variation was attributed to the increased sulphur dioxide pollution of the atmosphere in the winter, caused by the combustion of coal in open grates. It was concluded that there was a causal relationship between the quantity of ferrous sulphate and the effective life of the paint. It was suggested that these soluble deposits of ferrous sulphate short-circuit the resistance of the paint film and, since paint films are very permeable to water and oxygen, the ferrous sulphate will become oxidised and hydrolysed with the production of voluminous rust, which will rupture the film at numerous points, thus giving rise to the characteristic type of failure seen on painted rusty surfaces. 

The Karl Fischer procedure has now been simplified and the accuracy improved by modification to a coulometric method (Chapter 14). In this procedure the sample under test is added to a pyridine-methanol solution containing sulphur dioxide and a soluble iodide. Upon electrolysis, iodine is liberated at the anode and reactions (a) and (b) then follow the end point is detected by a pair of electrodes which function as a biamperometric detection system and indicate the presence of free iodine. Since one mole of iodine reacts with one mole of water it follows that 1 mg of water is equivalent to 10.71 coulombs. 

Pure sulphur dioxide is absorbed at 295 K and atmospheric pressure into a laminar water jet. The solubility of SO2, assumed constant over a small temperature range, is 1.54 kmol/m-1 under these conditions and the heat of solution is 28 kJ/kmol. 

Chlorosulphonated polyethylene is obtained by reacting low density polythylene with chlorine in presence of sulphur dioxide using carbon tetrachloride as solvent. The product contains 30 per cent chlorine and 1.5 per cent sulphur. This is a sticky rubbery material and is soluble in chlorinated hydrocarbon solvents. It can be vulcanised by heating with metal oxides like litharge or magnesium oxide in presence of water. The cross-linked product is found to be resistant to chemical attack and is used in gaskets, hoses, etc. 

The chloro-mlphito-deTivei.tvve, [Pt(NH3)2Cl.SO )H], is produced by the action of sulphur dioxide on a boiling solution of the ehloro-eom-pound. It is readily soluble in water. 

Liquid sulphur dioxide, says P. Walden,33 readily dissolves sodium and potassium bromides, and C. J. J. Pox has shown that at 25° the solubility S of sulphur dioxide in soln. of sodium bromide, unlike sodium chloride, is greater than it is in water, viz. 32 76. Thus for soln. of these salts of normality N, the solubility of sulphur dioxide is ... 

Hence the solubility of sulphur dioxide in sodium chloride soln. is less than it is in water, and in sodium bromide soln. greater and the difference is the greater... 

Nitrogen sulphide is insoluble in water, slightly soluble in alcohol and ether, somewhat soluble in carbon disulphide and benzene. At room temperature it is hydrolysed to some extent by water to form free sulphur, sulphur dioxide and ammonia. Its specific gravity is 2.22. 

The dioxides, which are formal by direct union of the dements, arc most characteristic. They arc acidic, and with water produce aeids of the type OX(OI 1 )2. Unlike sulphur dioxide, the dioxides of selenium and tellurium arc solids at ordinary temperatures the corresponding acids are also solids, but whereas selenious acid is readily soluble in water, tellurous acid is only very slightly soluble. The following heats of formation have been determined 1 M... 

Below 50° C. the solubility of sulphur dioxide in water does not obey Henry s Law. In the following table the solubility is given as grams of sulphur dioxide per 100 grams of water when the partial pressure of the gas is equal to 760 mm. of mercury. 

Certain organic liquids also dissolve sulphur dioxide, and a direct comparison of the solubility in water and in chloroform has been effected by partition experiments,4 in which measurement is made of the distribution of the gas between the two solvents in contact with one... 

Sulphur dioxide dissolves in aqueous solutions of inorganic salts frequently more readily than in pure water. With most salts, excluding sulphates, compounds appear to be formed in solution of the general type MX. SO 2, where M and X stand for univalent metal and negative radical, respectively.2 The solubility curve of sulphur dioxide in sulphuric acid of concentration ranging from 55 to 98-5 per cent, is interesting. A minimum occurs at 85-8 per cent, acid, and from that point the curve inclines sharply upwards for both increase or decrease of sulphuric acid concentration.3... 

At the point of minimum solubility of the sulphur dioxide the composition of the solvent closely approximates to that required for the monohydrate H2S04.H20 (namely 84-5 per cent, acid), and it is significant that other physical properties of the acid pass through critical values at this concentration (see p. 168). 

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