Thiosulphate anion

P2 = 2.0 X 10 , respectively. The concentrations of the associates and cationic forms in both the systems were calculated depending on the concentrations of sulphate and thiosulphate anions. The degree of formation of the associates at equal concentrations of these anions was approximately the same [304]. 

In the thiosulphate anion, S203, it is important to know how each sulphur is bonded. 

The problem is further highlighted by such complex anions as the thiosulphate anion, S2032-, ... 

Here the divalent thiosulphate anion was chosen, as with sulphate precipitation of CaSOg would occur. 

Silver chloride is readily soluble in ammonia, the bromide less readily and the iodide only slightly, forming the complex cation [Ag(NH3)2]. These halides also dissolve in potassium cyanide, forming the linear complex anion [AglCN) ] and in sodium thiosulphate forming another complex anion, [Ag(S203)2] ... 

Chlorate, D. of as silver chloride, (g) 479 by potassium dichromate, (ti) 378 by sodium thiosulphate, (ti) 394 Chloride and bromide, separation of on an anion exchanger, 209... 

Fortin, C. and Campbell, P. G. C. (2001). Thiosulphate enhances silver uptake by a green alga role of anion tranporters in metal uptake, Environ. Sci. Technol., 35, 2214-2218. 

An unusual reaction of methoxythiocarbonyl chloride with tetra-n-butylammo-nium iodide in the presence of sodium thiosulphate leads to the formation of 0,5-dimethyl dithiocarbonate [49], The reaction appears to involve a reduction step, with the iodide anion being regenerated from the released iodine by the thiosulphate ions (Scheme 4.7). In the absence of the thiosulphate ions, the thiocarbonyl chloride decomposes to yield chloromethane and carbonyl sulphide. 

The observation that in the electrolysis of ammonium thiosulphate solution tetrathionic acid is formed at the anode also belongs to this class, because the process is not one of the coupling of discharged anions, but an anodic oxidation of the thiosulphate.11... 

Lee and Field [318] have discussed a technique of post-column fluorescence detection of nitrite, nitrate, thiosulphate and iodide anions by high performance liquid chromatography. These anions react with cerium(IV) to produce fluorescent species in a post-column packed bed reactor. 

Takana et al. [344] used high performance liquid chromatography on an anion exchange column with differential pulse polarographic detection to determine thiosulphate and tri, tetra-, penta- and hexathionates in trade effluents. The method is accurate to within 10% at the 0,001 1 mM concentration range. 

Jones [5] carried out a simultaneous separation of non organic cations (eg calcium, potassium and sodium) also anions (eg nitrate, thiosulphate, cyanide and thiocyanate) by ion chromatography using a single column coated with weak/strong charged three welterionic bile salt micelles. 

Identification of gases Many anions (e.g. carbonate, sulphide, sulphite, thiosulphate, and hypochlorite) are usually identified by the volatile decomposition products obtained with the appropriate reagents. Suitable apparatuses for this purpose are shown in Fig. 11.30. The simplest form (a) consists of a semimicro test-tube with the accompanying filter tube a strip of test paper (or of filter paper moistened with the necessary reagent) about 3-4 mm wide is suspended in the filter tube . In those cases where spray is likely to affect the test paper, a loose plug of cotton wool should be placed at the narrow end of the filter tube . Apparatus b is employed when the test reagent is a liquid. A... 

Sulphides, sulphites, thiosulphates, cyanides, cyanates, fluorides, nitrites, and acetates interfere. The sulphur-containing anions can be quantitatively oxidized to sulphates by hydrogen peroxide ... 

Bromides and iodides interfere because of the liberated halogen the test is not trustworthy in the presence of chromates, sulphites, thiosulphates, iodates, cyanides, thiocyanates, hexacyanoferrate(II) and (III) ions. All of these anions may be removed by adding excess of nitrate-free Ag2S04 to an aqueous solution (or sodium carbonate extract), shaking vigorously for 3-4 minutes, and filtering the insoluble silver salts, etc. 

The presence of thiosulphate, sulphide, cyanide, sulphite, hexacyano-ferrate(II), and (III), however, introduces difficulties in the subsequent separations, hence these anions must be tested for first and, if present, removed. 

The iodine is removed by adding a thiosulphate, and the selenium remains as a reddish-brown powder. Tellurites react under these conditions forming the complex anion, [Tel6]2, which also has a reddish-brown colour it is, however, decomposed and decolourized by a thiosulphate, thus permitting the detection of selenium in the presence of not too large an excess of tellurium. 

The limitations to the preparation of U(III) complexes in aqueous solutions can be judged from the observation that the addition of phosphate, carbonate, nitrate, nitrite, sulphite, thiosulphate, or carboxylic acid anions to a U(III) sulphate solution all lead to rapid oxidation of the uranium, though color changes that suggest complex formation may occur (57). 

Further applications are described for sulfur (Fig. 2.6) and copper in water by reversed-phase or ion-exchange high-performance liquid chromatography . Also anions such as thiosulphate and polythionates were separated from environmental samples by HPLC (anion-exchange) . The sensitive detection was made possible by reaction with Ce(lV) after separation and fluorimetry of Ce(lII) ions. 

Detailed data have been published on the behaviour of some elements on anion exchangers in the media of fluoride [152], nitric acid [153], sulphuric acid [154,155], and in the mixed medium HCl-acetic acid-water [138], Studies were also carried out on the behaviour of elements on strongly basic anion exchangers in the media of HBr [156,157], phosphoric acid [158], oxalic acid [159], thiocyanate [160], tartrate [161], and thiosulphate [162],... 

From among other cations, only Ti " gives a greenish-coloured complex with cuproin, but its colour is much weaker than that of the purple copper(l) complex. Of the anions, cyanide, thiosulphate, oxalate, and EDTA interfere in the determination of copper [27,28]. 

Analytical properties of thiosulphate and polythionate anions have been reviewed [85]. 

Thiosulphates and Thionates. A neutron-diffraction study has shown that in barium thiosulphate monohydrate the tetrahedral 8203 anion has the bond lengths S—8=1.979 and 8—0= 1.472-1.483 A the Ba—8 distances are 3.355 and 3.424 A. A crystal structure determination of bis(ethylenethiourea)zinc(ii) thiosulphate has shown that each zinc atom is tetrahedrally surrounded by three sulphur atoms (two from etu and one from the thiosulphate group, with the mean distance Zn—8 = 2.320 A) and one oxygen atom from the 82O3 group. Crystalline Zn(NH3)3(8203),H20 and Cd(NH3)3(8203) have been prepared and characterized spectral data indicate that the 8203 ion is unidentate and is bonded to the metal through sulphur. 

Hydrolysis of the esters (107) and (108) involves concomitant cleavage of both C-O and P-O bonds, the relative contributions of such fragmentations depending on experimental conditions. The reaction at carbon is favoured by an increa.se in temperature and is accelerated (60 times) by thiosulphate. Reaction at the P-O bond is favoured relative to that at the C-O bond by the addition of an organic. solvent (acetone) to the aqueous medium. Only P-O cleavage occurs in THF, in which the process is accelerated by fluoride anion (100 times). ... 

Sulphides, sulphites, thiosulphates, cyanides, cyanates, fluorides, nitrites, and acetates interfere. The sulphur-containing anions can be quantitatively oxidized to sulphates by hydrogen peroxide. The modified procedure in the presence of these anions is therefore to stir a drop of the test solution with 4 drops 3% hydrogen peroxide, then to add 2 drops m sulphuric acid, and to continue as above. Cyanides are rendered innocuous by treating the test solution with 4 drops of a saturated solution of mercury(II) chloride, followed by 2 drops sulphuric acid, etc. the slightly dissociated mercury(II) cyanide is formed. Nitrites can be removed by treatment with aniline hydrochloride. 

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