M.S.Prasada Rao

Thallimetric oxidations—V: Titrimetric and spectrophotometric determination of hydrogen peroxide

Titrimetric and spectrophotometric methods have been developed for the determination of hydrogen peroxide at mmole and mumole levels respectively. In these methods thallium(III) is used as the oxidant and the reduced thallium(I) is determined oxidimetrically with potassium bromate in the titrimetric method and by measuring the absorbance of thallium(III) at 260 nm in the presence of 0.1M hydrochloric acid and 1M perchloric acid in the spectrophotometric method. Photochemical redox methods for the estimation of hydrogen peroxide in the presence of a number of diverse ions are described.

A Photochemical redox method for the estimation of thallium(III)

A convenient photochemical redox method for the estimation of thallium(III) by reduction with oxalic acid followed by oxidation of thallium(I) with potassium bromate has been developed. The reduction is carried out in the presence of small concentrations of chloride and bromide as catalysts.

Thermal decomposition of potassiumbis-oxalatodiaqua-indate(III) monohydrate

Indium (III) is precipitated with oxalic acid in the presence of potassium nitrate maintaining an overall concentration of 0·125 M in HNO3. Chemical analysis of the complex salt obtained indicates the formula, K[In(C2O4)2]·3H2O. Thermal decomposition studies show that the compound decomposes first to the anhydrous potassium indium oxalate and then to the final mixture of the oxides through formation of potassium carbonate and indium (III) oxide as intermediates. Isothermal study, X-ray diffraction pattern and IR spectral data support the proposed thermal decomposition mechanism.

Tin(II) sulphate as a new reductimetric titrant—direct titration of thallium(III) with use of ion-pair and redox indicators

The use of tin(II) sulphate as a direct reductimetric titrant for thallium(III) has been investigated, with potentiometric and visual detection of the end-point. Some azure dyes are used as redox indicators and Methylene Blue is used as both a redox and an ion-pair indicator.

Photochemical reduction of thallium(III) with hydrogen peroxide

A convenient method for determination of thallium(III) is based on photochemical reduction with hydrogen peroxide in the presence of bromide as catalyst, followed by oxidation of thallium(I) with potassium bromate.

Thermal decomposition of ammonium dioxodiaquaperoxyoxalatouranate(VI) hydrate

Abstract The chemical analysis and the thermal decomposition of the complex are consistent with the formation of an intermediate, which is a mixture of ammonium carbonate and uranium trioxide, subsequently decomposing to ammonium uranate. The ammonium uranate decomposes to uranium trioxide which is finally reduced to U3O8. Thermal decomposition, infrared absorption spectra, and X-ray diffraction patterns are used to characterize the complex and the intermediate products of the thermal decomposition. Based on this data, the complex salt may be represented as (NH4)2[UO2(O2)(C2O4)(H2O)2]·H2O.

Thallimetric oxidations-VI Titrimetric and spectrophotometric methods for the determination of phosphite and analysis of binary mixtures of phosphite and oxalate.

Titrimetric and spectrophotometric methods have been developed for the estimation of phosphite at mmole and mumole levels, respectively. Thallium(III) is used as an oxidant and the thallium(I) produced is determined either oxidimetrically with potassium bromate or by measurement of the absorbance of thallium(III) at 260 nm in the presence of 0.1 M hydrochloric acid and 1 M perchloric acid. Based on the fact that phosphite and oxalate are oxidized under different conditions, methods are described for the analysis of binary mixtures of phosphite and oxalate. A method is also described for estimation of thallium(III) with phosphite as reluctant, and is applied for analysis of mixtures of thallium(I) and thallium(III).

Photochemical thallimetric oxidations-estimation of formic acid.

A simple, rapid and convenient redox method has been developed for the estimation of formic acid. Formic acid is photochemically oxidized with thallium(III) in the presence of bromide as catalyst, and the thallium(I) formed is determined by titration with potassium bromate. The procedure can also be used for the estimation of thallium(III) with formic acid as reductant.

Chemical speciation of oxalato complexes of indium(III)

Abstract Chemical speciation of binary complexes of indium(III) with oxalic acid has been investigated pH metrically at 303 K and at an ionic strength of 0.2 mol dm−3. The approximate formation constants have been calculated with the computer program SCPHD utilizing the experimental data obtained by monitoring H+ ion concentration. The formation constants thus obtained are refined with the computer program, MINIQUAD75 using primary alkalimetric data. The selection of the best-fit chemical model is based on the statistical parameters and residual analysis. The major complexes formed are In(C2O4)2−, In(C2O4)33−, [In(C2O4)2OH]2− and [In(C2O4)2 (OH)2]3−. The distribution patterns of the different species with the pH values showed that In(C2O4)2− is the predominant species.

Thermal decomposition of potassium dioxodiaquaperoxyoxalatouranate(VI)

Abstract Potassium dioxodiaquaperoxyoxalatouranate(VI) was obtained by reaction of uranyl nitrate with oxalic acid and then hydrogen peroxide in the presence of potassium ion. The complex was subjected to chemical analysis. The thermal decomposition behavior of the complex was studied using TG, DTA and DTG techniques. The solid complex salt and the intermediate product of its thermal decomposition were characterized using IR absorption and X-ray diffraction spectra. Based on the data from these physicochemical investigations, the structural formula of the complex was proposed as K 2 [UO 2 (O 2 )C 2 O 4 (H 2 O) 2 ].