Volumetric method for the estimation of tin(II)

Summary A rapid and easy volumetric method for the estimation of tin(II) has been proposed using copper sulphate solution. The method consists of liberating iodine from an excess of potassium iodide solution by the addition of a known volume of a standard copper sulphate solution and to this, adding a known volume of stannous chloride solution. The remaining iodine in the solution is titrated against a standardized solution of sodium thiosulphate. Carbon dioxide atmosphere is not essential during the titration. However, freshly boiled conductivity water cooled and stored under carbon dioxide atmosphere should be used for making up the solutions.

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Zusammenfassung Zinn(II) kann volumetrisch auf schnelle und einfache Art bestimmt werden, wenn man durch Zugabe einer bekannten Menge Kupfersulfatlösung zu überschüssiger Kaliumjodidlösung Jod in Freiheit setzt, die Zinn(II)-probelösung zugibt und überschüssiges Jod mit Thiosulfatlösung zurücktitriert. Es ist nicht erforderlich, die Titration in C0₂-Atmosphäre durchzuführen, jedoch soll zur Herstellung der Lösungen ausgekochtes und unter CO₂ aufbewahrtes Leitfähigkeitswasser verwendet werden.

     

On the iodometric determination of the bromide ion

The oxidation of bromide effected by chlorine was investigated and it was established that it runs down in two steps. In the course of the first step in a medium of pH between 6.5-7.5, Br⁺ùOH^- electromer hypobromous acid forms. This BrOH electromer leads, on further oxidation, to the product BrCl₅, furnishing on hydrolysis bromate. In a medium, in which the pH is adjusted to about 8.5-9 the hydrolysis takes place at such a rate that it can be used for analytical purposes.On the basis of these investigations the determination of the bromide ion amounting to 0.1-25 mg can be carried out rapidly with an error of a few tenths of one per cent. Besides the oxidizing substances only iron, copper, mercury and molybdenum ions interfere with the procedure. The interfering ions can either be eliminated by treatment with soda and hydrogen sulphide, or by the distillation of bromine.     

The use of 2,6-dichlorophenol-indophenol as indicator in iodometric titrations with ascorbic acid

2,6-Dichlorophenol-indophenol can be used as an indicator in iodometric methods, provided that near the end-point the solutions can be buffered with potassium hydrogen carbonate, so that ascorbic acid can be used as the titrant. Procedures for the determination of iodine, chlorine, bromine, hypochlorite, Chloramine T, bromate, iodate, permanganate, dichromate, copper(II), hydrogen peroxide, peroxydisulphate, thiosulphate, sulphite, sulphide, hydrazine and formaldehyde are described.     

Rapid iodometric determination of copper in some copper-base alloys

Copper-base alloys, especially those containing tin, are readily dissolved in a mixture of hydrofluoric and nitric acids. In the resulting solution copper can be titrated iodometrically in the conventional manner.     

A new method for the iodometric determination of sulphoxides

A method is described for determination of sulphoxides through their reaction with iodide in a trifluoroacetic acid/acetone medium to produce iodine, which is then titrated with thiosulphate.     

The application of thiosalts in analysis : Estimations based on decomposition of thiosalts part B. estimation of molybdenum and tin

1. It has been shown that molybdenum can be precipitated quantitatively by adding excess of concentrated ammonium sulphide to a molybdate solution and then decomposing the thiosalt with excess of hydrochloric acid. 2. The weight of the precipitate corresponds to the formula MoS₃.2H₂O and the quantity of metal can be estimated by multiplying the weight of the precipitate by a constant factor. 3. The same method is also applicable to the gravimetric estimation of tin. The precipitate of stannic sulphide is easily filterable and its weight corresponds to the formula SnS₂.2H₂O. 4. The general method in its simple form has not been found to be applicable to vanadium, platinum and gold.     

The determination of tin in biological samples

A rapid method is described for the determination of tin in biological material, using¹²³Sn (T=40 m). The chemical procedure is based on the nearly quantitative extraction of tetravalent tin into toluene from an acid 1.3M iodide solution. The recovery is determined by spiking the solution with¹¹³Sn and measuring the activity of the^113mIn daughter in the counting sample. The lower limit of the determination is ?0.01μg. Results are given for standard kale powder and dried animal blood.     

The synthesis of some ferrocenyl tin hydrides

Tin hydrides containing a ferrocenyl (Fc) group have been synthesized. They reduce haloalkanes in good yields and their decomposition products are easily separated from the products by oxidizing the ferrocene compounds to ferrocenium ions.     

The complexometry of tin(IV)

Tin(IV) very readily hydrolyses in solution, and forms hydrous tin oxide SnO(2)2.nH(2)O even in rather strongly acidic solution. In spite of a lack of reliable data on the hydrolysis of tin(IV) a consistent picture of the behaviour of tin(IV) in solution has been constructed. Some values for the formation of hydroxide and chloride complexes were deduced from electrochemical data. In agreement with more or less qualitative remarks by other investigators a value of log k(so) = -3 has been found for the solubility constant. For the stability constant of tin(IV)-EDTA, log K(SnY) = 34.5 was found experimentally. A survey is given of the pitfalls which exist in handling tin solutions. A back-titration procedure is presented that provides for the complexometric determination of tin(IV) at concentrations down to 3 ppm, with an error of 1% or better. Thorium is used as back-titrant with Semi-Xylenol Orange as indicator. The method has successfully been applied to the analysis of organotin compounds.     

Controlled potential iodometric determination of iron after extraction with di-isopropyl ether

A selective method for the determination of small amounts of iron in different kinds of samples with complex matrices has been developed. The iron in a sample is converted into the ferric state and after extraction with di-isopropyl ether the ferric iron is iodometrically determined with a controlled-potential apparatus previously described. Iron concentrations lower than 1 ppm can be determined.     

A rapid iodometric method for the determination of copper and zinc

A method has been described for the iodometric simultaneous determination of zinc and copper. Copper is determined in the presence of sufficient KCNS and a small amount of KI. This is followed by the titration of the iodine equivalent to the zinc, which is liberated by the addition of potassium ferricyanide solution.Interference is eliminated completely by keeping the solution neutral or just acid with phosphoric acid.Within the range under investgation, results are obtained which are accurate to ± 0.7%.     

The microdetermination of stannous tin with N-bromosuccinimide

A new titrimetric method for the microdetermination of stannous tin, e.g., stannous chloride is proposed. The mechanism of the reaction in the presence of dilute hydrochloric acid is discussed. The determination of stannous tin is done on concentrations ranging from 10 mg to 100 μg. The experimental error does not exceed ±2%. Comparative analysis of tin sheets, rods, and foils by the proposed method and the iodine method is reported. The method has been shown to be suitable for the determination of tin in canned foods.     

The corrosion of tin oxide semiconducting glazes

An SnO₂Sb₂O₅ glaze, which seems the most promising among semiconducting porcelain glazes for high voltage applications, has been operated as electrode in Na₂SO₄ solution, to study under controlled conditions, its corrosion behaviour. The morphology of the corrosion has been observed by microscopy. Metallic tin produced by electrochemical reduction has been identified by X-ray diffraction.     

The direct synthesis of triorgano tin compounds

The synthesis of triorganotin halides directly from tin is described. The addition of an alkyl halide to tin metal dispersed in a molten quaternary halide rapidly and selectively produces the trialkyltin halide and a by-product containing the quaternary as a tin halide complex. The quaternary halide, the tin, and the halide ion are all recovered from the by-product by electrolysis and reused.