Sulphite ions sulphide

However, the sulphide ion can attach to itself further atoms of sulphur to give polysulphide ions, for example Sj , Sj , and so these are found in solution also. Further, the sulphite ion can add on a sulphur atom to give the thiosulphate ion, S203 which is also found in the reaction mixture. 

The following interfere with the test strong reducing agents (hydrogen sulphide, dithionites, sulphites and selenites) V, U, Te, Hg, Bi, Au, Pd, Se, Te, Sb, Mo, W, Co and Ni. The reaction is not selective, but is fairly sensitive it can be used in the analysis of the Group IIB precipitate. Since iron(II) ions have no influence on the test, it may be applied to the tin solution which has been reduced with iron wire. 

Any sulphite ions or sulphide ions present are oxidized with hydrogen peroxide (about 3 to 5 %). 

Sulphite ions and sulphide ions are eliminated by adding dilute hydrogen peroxide solution drop by drop while cooling the solution. 

Further reaction between hydrogen sulphide and the sulphite ion yields sulphur together with thionic acids) ... 

General corrosion damage was the cause of failure of an A1 alloy welded pipe assembly in an aircraft bowser which was attacked by a deicing-fluid — water mixture at small weld defects . Selective attack has been reported in welded cupro-nickel subjected to estuarine and seawater environments . It was the consequence of the combination of alloy element segregation in the weld metal and the action of sulphate reducing bacteria (SRB). Sulphide-coated Cu-enriched areas were cathodic relative to the adjacent Ni-rich areas where, in the latter, the sulphides were being continuously removed by the turbulence. Sulphite ions seemed to act as a mild inhibitor. 

Salmonella typhi, in the presence of glucose, reduces bismuth sulphite to bismuth sulphide, a black compound the organism can produce hydrogen sulphide from sulphur-containing amino acids in the medium and this will react with ferrous ions to give a black deposit of ferrous sulphide (Table 1.2). 

A sensitive colour test for sulphite ions consists in adding, drop by drop, a 0-01 per cent, solution of Fast Blue R crystals, shaking after each addition, until the violet coloration disappears and a yellow solution is produced the test is sensitive to one part of sulphurous acid in about 175,000. Thiosulphates and polythionates do not interfere, but sulphides and hydroxides must be absent.1... 

The method is based on the partitions of the anions to a cationic micelle phase and shows different selectivity from ion exchange chromatography In a kinetic method [13] for the determination of thiocyanate, sulphite and sulphide the anions are reacted with 5,5 dithiobis (2-nitrobenzoic acid) in aqueous cetyltrimethyl/ammonium bromide micelles. 

It is possible that Gottschalk and Buehler (1912) carried out the oxidation with an excess of oxygen which would not occur in nature at the oxidation interface of a mineral deposit. Granger and Warren (1969) conducted experiments to investigate the oxidation of iron sulphides by an aerobic aqueous phase in a sterile system. The objective was to study the formation of unstable intermediate ions during the oxidation process. The intermediate sulphur species detected were sulphite and thiosulphate. In general these products are more easily oxidised than the metallic sulphides and are stable only if removed from the oxidising environment. 

A kinetic study of the oxidation of sulphite ions to sulphate ions by gaseous oxygen in melts of lithium and potassium chlorides at temperatures between 414 and 504 °C has been carried out, and a possible reaction mechanism proposed.14 The interaction of oxygen at 20 °C with hydrogen sulphide presorbed at 55 °C and vice versa has been investigated.15... 

The bleaching of Methylene Blue by 8203 affords a sensitive method for determination of thiosulphate [70]. It is possible to determine thiosulphate after extraction of its ion-associates with some basic dyes, e.g., Rhodamine B, Rhodamine 6G, or Crystal Violet [71]. Thiosulphate present in concentrations of the order of 10 M have been determined after the oxidation with iodine by measuring the absorbance due to I3 [72]. Thiosulphate can also be determined in an indirect reaction, in which 8203 reacts with Hg(II) thiocyanate to release SCN which gives a colour reaction with Fe(III) [73]. A method for simultaneous determination of thiosulphate, sulphite, and sulphide has been proposed [74]. 

Sulphur (S) occurs in soils usually as sulphites, sulphates, sulphides and in organic compoimds. However, the most accessible form is sulphate (SO ). The turbidimetric procedure is widely used in the estimation of available S in the soil due to its rapidity. However, erroneous results are obtained in case the soil is rich in organic matter. Soil is shaken with a solution of monocalcium phosphate, containing 500 ppm P. The phosphate ions displaces the adsorbed sulphate. The calcium ions depresses the extraction of soil organic matter, thus eliminating contamination from extractable organic S. The method extract soluble plus a fraction of adsorbed The filtrate is then analysed for S by the turbidimetric procedure. In this method... 

The kinetics of the electrochemical reduction of sulphamic acid giving sulphite ion and ammonium hydroxide have been studied polarographically in aqueous solution in the presence of various salts51. The electrodissolution of lead sulphide, prepared by fusion or by sintering in sulphamic acid, has been measured by cyclic voltammetric, potentiodynamic and potentiostatic methods52. 

Another important detector for ion chromatography is the electrochemical detector (ECD). This makes it possible to detect anions such as cyanide, nitrite, sulphide, bromide, iodide and sulphite with maximum sensitivity. Thanks to its specific detection capabilities it is also possible to identify these ions without interference alongside high concentrations of other ions which may also display similar retention values (Fig. 75). 

Under anaerobic conditions sulphite is reduced to hydrogen sulphide, which causes black colouring of the medium with iron ions as a result of FeS or FeS2. 

Aqueous sodium hydrogen sulphite and iodide ions reduced thiolan 1-oxide to thiolan much faster than they reduced the six- and seven-membered analogues to the corresponding sulphides. The reactions... 

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