Sulphide sulphite

BorreU L, Cervera-March S, Gimenez J, Simarro R, Andujar JM (1992) A comparative study of CdS-based semiconductor photocatalysts for solar hydrogen production from sulphide + sulphite substrates. Sol Energy Mater Sol Cells 25 25-39... 

Subrahmanyam, M., Supriya, V.T., and Reddy, P.R., Photocatalytic H2 production with CdS-based catalysts from a sulphide/sulphite An effort to develop MgO-supported catalysts, Int.. Hydrogen Energ., 21, 99,1996. 

The sodium chloride and sulphate regularly found in Leblanc soda ash are not usually injurious the insoluble matter should not exceed 1 to 1J per cent. It consists principally of calcium carbonate, alumina, silica, and ferric oxide. The sulphides should not be detectable by lead paper thiosulphates are destroyed in calcining the ash sulphites are usually present and can be detected by iodine soln. and sodium hydroxide, except in the so-called caustic ash, does not usually exceed 1 per cent. The moisture in fresh ash ranges below one per cent. Owing to the mode of preparation, ash by Solvay s process is more pure than that prepared by Leblanc s process. It does not contain sodium hydroxide, sulphides, sulphites, or thiosulphates it may contain a slight excess of carbon dioxide a little sodium sulphate is always present iron, alumina, and silica are present in minute traces sodium chloride is perhaps the only... 

The various kinds of alkali, cf commerce usually contain a. greater or less proportion of chlorides and sulphates. The presence of these dees not interfere In the slightest degree with the above methods of estimation. In some cases, however, sulphides, sulphites, and hyposulphites aro also present, and these, neutralizing a certain quantity of the tost acjd, Tender the determinations more or less inaccurate. The first of these salts evolves sulphide of hydrogen, the second sulphurous acid, and the last hyposulphurous acid, which is immediately decomposed into sulphurous ecitl... 

For the use of the iodometric method in the analysis of mixtures containing sulphide, sulphite and thiosulphate, see Kurtenacker and others, Zeitsch. an.org. Chem., 1924, 141, 297 1927, 161, 201 and for mixtures of sulphide, polysulphide and thiosulphate, see Sohulek, Zeitsch. anal. Chem., 1925, 65, 352. For titration methods using potassium iodate, see Jamieson, Amer. J. Sci., 1915, 39, 639 also Ivanofi, J. Buss. Phys. Chem. Soc., 1914, 46, 419 Dimitrow, Zeitsch. anorg. Chem., 1924, 136, 189. 

Sulphides, Sulphites, and Thiosulphates. On I ouriug I cc. of the 1 20 aqueous solution into 10 it. of decinurnwd silver nitrate solution, a yellowish-while, precipitate forms. winch should not become darker (gray to brownish to lihicki on... 

This technique has found limitations in the determination of bromide mixed halides, iodide, iodate, nitrite, nitrate, sulphide, sulphite, thiocyanate, thiosulphate and isobutyrate in non saline waters. 

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 ... 

The precipitate is soluble in ammonia solution and in solutions of caustic alkalis. Large quantities of hydrochloric acid interfere with the test and should preferably be removed by evaporation to a small volume with excess concentrated nitric acid. Reducing agents, such as sulphides, sulphites, hexacyano-ferrate(II)s, and tartrates, seriously affect the reaction, and should be destroyed before carrying out the test. 

Sulphide, sulphite, thiosulphate, and sulphate in the presence of each other Upon the addition of dilute acid to the mixture, the hydrogen sulphide, liberated from the sulphide, and the sulphur dioxide, liberated from the sulphite and thiosulphate, react and sulphur is precipitated this complication necessitates the use of a special procedure for their separation (see Table IV.2). 

Table IV. 2 Separation of sulphide, sulphite, thiosulphate, and sulphate Shake the solution with excess of freshly precipitated CdC03, and filter.

Sulphide, sulphite, and thiosulphate in the presence of each other It is... 

Sulphur (S, at. mass 32.06) occurs in the oxidation states -II (in sulphide), IV (in SO2 and sulphite), and VI (in H2SO4 and sulphate). Sulphur dissolves in certain organic solvents (e.g., CS2 and CeHe) when dissolved in an alkali metal sulphide solution, it yields yellow polysulphides (S + nS —> Sn+i j. When heated with an alkaline solution of sulphite, sulphur forms thiosulphate. Sulphide, sulphite, and thiosulphate are reducing agents. Persulphate has strongly oxidizing properties. Complexes are formed by sulphide e.g., with As, Sb, Mo), and also by thiosulphate [e.g., with Ag, Cu, and Fe(lII)]. The most stable sulphur species is sulphate, which forms sparingly soluble compounds, for example with Ba and Pb, and stable soluble complexes with Zr and Th. 

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. 

Sulphide, sulphite, and thiosulphate in the presence of each other it is assumed that the solution is slightly alkaline and contains the sodium salts of the anions, e.g. the soda extract is used. 

It is used as a reagent in qualitative analysis for the detection of sulphides, sulphites, aldehydes and ketones containing the CH3—CO—R group. It is also used as a reference compound for the cahbration of a Mossbauer spectrometer. Sodium nitroprusside is used to detect iUicit substances, such as secondary amines, in forensic laboratories (Simon s test). It is used to control blood pressure and to treat hypertension. 

The use of hydroxyl-terminated polysulphide polymers is limited to applications where outstanding solvent resistance is required. The reason for this is that the best solvent resistance is shown by polymers with a high sulphur content but these cannot be prepared with thiol end-groups by the hydro-sulphide/sulphite treatment because sulphite removes high rank sulphur from the polymer backbone (see section 19.4.2). Thus since polysulphide polymers of high sulphur content cannot be subjected to this after-treatment, they are supplied as hydroxyl-terminated polymers of high molecular weight. 

---