Telluric Acid Research Articles

Oxidation of sulphides with alkaline potassium permanganate

Sulphides are oxidised with potassium permanganate in alkaline medium to give dithionate. A method based upon this reaction is proposed for the determination of sulphides. The method consists in mixing the sulphide solution with an excess of permanganate in presence 1–2 M NaOH and 0.2 g telluric acid. The excess permanganate is then treated with ferrous ammonium sulphate in acid medium and the excess ferrous titrated with permanganate.

Production de 131I sans porteur a partir d'acide tellurique

The described method uses telluric acid (H 6TeO 6) as a target for the production of 131I in nuclear reactors. The performed experiments indicate that it is sufficient to dissolve the target in water in presence of a strong acid and to distil in order to carry over the iodine as I − and I 2. The method eliminates the difficulties of target dissolution and makes it possible to obtain a very pure distillate after an easily performed separation. It is possible to use the sulphuric and phosphoric acids indefinitely but an excess of either acid increases the distillate acidity. The irradiations were carried out in the BR 1 reactor at Mol in a thermal flux of about 10 9 to 2 × 10 12 neutrons/cm 2/sec in temperature conditions never exceeding 90°C. The valency-state of the distilled iodine seems to be independent of the flux and of the integrated flux to which the target is submitted. Apparatus and production method are described.

Ion-exchange studies of solutions of tellurates

The sorption of tellurium and of chloride by Amberlite I.R.A. 400-Cl from telluric acid solutions, containing 1·0-0·07 g atoms of tellurium per litre, has been studied at various pH values. The results have been interpreted in terms of the sorption of a tetra- and a tri-tellurate ion, in addition to the non-condensed ions H 5TeO 6 − and H 4TeO 6 =. The actual ions sorbed appear to depend both upon the pH and the tellurium concentration of the solutions. An attempt was made to correlate the data obtained by ion-exchange methods with those supplied by an examination of the ultra-violet absorption spectra of telluric acid and sodium tellurate solutions.

Studies in polarography: III. Reduction of permanganate in presence of telluric acid at the dropping electrode

AbstractThe polarography of alkaline permanganate solutions in presence of telluric acid has been studied. It is shown that reduction of Mn+7 passes through an ill‐defined zero wave to Mn+3. This latter is then reduced to Mn+2 along a sloping wave. The waves of telluric acid and the Mn+2‐Mn are vitiated by the precipitation of manganous tellurate. The lowering of id of the Mn+7/Mn+2 wave and the early reduction of telluric acid indicates the formation of a double salt between permanganate (A) and tellurate (B) of the formula AB2.

The separation of carrier-free tellurium tracers by paper chromatography

Paper chromatographic conditions for the purification of carrier-free tellurium tracers (from zirconium tracer and from copper in macro quantities), as well as for the separation of Te IV and Te VI ions, have been established. The low R F values of Te VI in butanol/HCl mixtures have been explained by the tendency of telluric acid to polymerization.

Colorimetric determination of manganese

The colour developed, when freshly formed manganese dioxide dissolves in alkaline tellurate solution is found to be suitable for the colorimetric determination of manganese. The colour obeys Beer's law within the concentration range 1.886.10 -4 - 7.54.10 -4 M. The colour is developed by oxidizing Mn(II) (in presence of 2.5M alkali) with the equivalent amount of H 2O 2 in the presence of 4 moles of telluric acid per mole Mn(II).

Oxidations with alkaline permanganate using monovalent thallium for the back titration: Estimation of trivalent antimony

Titration of Sb+3 with KMnO4 gives good results in the presence of telluric acid if the alkali concentration is kept below 0.5N. At higher alkalinities early end-points are attained except in the presence of tartaric acid. In the absence of telluric acid reduction of MnO 4 - at higher alkalinities than 0.5N NaOH gives Mn 2O 3. On titrating KMnO4 with trivalent antimony the former is reduced to MnO2. Quantitative results are obtained in the presence of NaOH and when telluric acid is present in the reaction medium. Reduction could not be checked at the manganate state in the presence of Ba+2 ions. The method consisting in oxidation of Sb+3 with excess Keno4, in the presence of telluric acid and 1–2 N NaOH followed by titrating back the excess of oxidant, with Tl+ gives accurate results. Amounts of Sb as low as 0.67 mg could be estimated in this way.

Oxidations with alkaline permanganate using monovalent thallium for the back titration: Estimation of hydrogen peroxide

Owing to the instability of hydrogen peroxide in alkaline solutions, direct oxidation with KmnO 4 did not yield accurate results.The back titration of KmnO 4 in the presence of IN NaOH and Ba +2 ions also gave inaccurate results. The reaction could not be checked at the manganate state. However, in the presence of 2 N NaOH and telluric acid quantitative data were obtained, which is not the case if telluric acid is absent. Another advantageous method is the oxidation of hydrogen peroxide with excess KmnO 4 in the presence of 1 N NaOH and telluric acid, followed by back titrating excess oxidant with monovalent thallium.

Studies in polarography: Part II reduction of telluric acid at the dropping mercury electrode

AbstractThe reduction of telluric acid at the dropping mercury electrode is studied in buffer solutions of pH 1‐12, in 0.1 M KCl, and in 0.01‐1 M NaOH. It is found that telluric acid is reduced under all conditions to elementary tellurium. The relation between the diffusion current and the concentration is excellent in 0.1 M KCl and 0.1 M NaOH within the concentration range of 1 × 10−4 −1 × 10−3 M and in ammoniacal buffer of pH 10 within the range of 2 × 10−4 −3 × 10−3 M. Maxima, except in 1 M NaOH, are occasionally met with, which could be suppressed by gelatin.

Oxidations with alkaline permanganate using monovalent thallium for the back titration: Estimation of hydrazine

Oxidation of liydrazine in alkaline solutions with KmnO 4, gives inaccurate results both in the presence of absence of telluric acid. The titration curve is characterized by two inflections. Titration of KmnO 4 with hydrazine gives good results in the presence of Ba +2 ions and 0.75–1 NNaOH (when MnO 4 - gives MnO 2 -) or in the presence of 0.5–2.5 N NaOH only (when MnO 4 gives MnO 2). Hydrazine could be estimated by oxidation with KMn0 4 either in the presence of Ba +2 ions or telluric acid, after which the excess permanganate is back titrated with monovalent thallium. The alkalinity is Kept at 1 N NaOH.

Oxidations with alkaline permanganate using monovalent thallium for the back-titration: Estimation of trivalent arsenic

In absence of Ba +2 ions arsenite reduces KMnO 4 in alkaline medium to MnO 2 without the appearance of an inflection at the manganate state. Reduction could be checked at the manganate in presence of 1 N NaOH and Ba +2 equal to 3 times that equivalent to MnO 4 -2 and arsenate, and when dilute arsenite solutions are applied viz.0.02 N In absence of Ba +2 ions the end-points are attained later than the MnO 2 stage except in 2–3 N NaOH. In presence of telluric acid good results are obtained at all alkalinities whence reduction is checked at Mn +4. As +3 could be estimated also by mixing with KMnO 4 either in the presence of Ba +2 ions + 1 N NaOH or in absence of Ba +2 ions + I.5–3 N NaOH and back-titrating the excess oxidant with monovalent thallium.

Hydrogen Peroxide Oxidation of Tellurium Dioxide

telluric acid have been reported in the literature. Probably the most widely used preparation is that of Mathers and co-workers, which is based on the action of potassium permanganate in an acid medium'6'. This method gives a very good yield of the crude product, but the impurities which are inherent in the preparation must be eliminated by repeated recrystallization from concentrated nitric acid solution. The method of Meyer and Franke'7' of oxidizing the free element with chloric acid, has given yields of ninety to ninety five percent. However, again the reaction products lead to a high concentration of impurities which must be eliminated.

Oxidations with alkaline permanganate using monovalent thallium for the back-titration: Determination of iodate, iodide and ferrocyanide

Iodate, iodide, iodine and ferrocyanide can be estimated by oxidation with KmnO 4 in alkaline media; the excess is back-titrated with TI 7. I - and I 2 are oxidized to IO 4 - in the presence of Ba +2 ions but only to IO 3 - in absence of such ions. The direct titration of IO 3 -, I - with KmnO 4 proved valueless. Ferrocyanide is oxidized by KmnO 4 in alkaline solutions and MnO 2 is formed. In the presence of telluric acid and 0.025–0.1 N NaOH satisfactory results are obtained. Reduction of MnO 4 - with ferrocyanide gives MnO 4 -2 and the results are variable, depending on the rate of adding the ferrocyanide.

The Stability of Potassium Permanganate in Alkaline Solutions Containing Telluric Acid

The Stability of Potassium Permanganate in Alkaline Solutions Containing Telluric Acid

Oxidations with alkaline permanganate using formic acid for back-titration: Determination of lead and thallium

Pb +2 (~37-0.6mg) and Tl + (45-0.9 mg) can bc estimated by mixing with KmnO 4 in presence of Ba +2 ions and I NNaOH. The excess KmnO 4 is then titrated with formic acid. A mixture of Pb +2 and Tl + is oxidized simultaneously with KMn0 4 in 0.1 N NaOH. Pb +2 interferes also when precipitated as sulphate or tellurate. In presence of SO 4 -2 and telluric acid, thallium can be titrated only when its concentration is not less than 30 mg, below which lead seriously interferes. Tl + can be accurately determined in the filtrate from the PbS0 4 precipitate.

Oxidations with alkaline permanganate using monovalent thallium for the back titration: Estimation of lead. selenium, tellurium and chromium

Monovalent-thallium can be successfully used for the back titration of KMnO 4 in the course of estimating Pb +2, Sc +4, Te +4 and Cr +3. Reduction of KMnO4 with Tl+ in alkaline solution yields MnO 4 -2 which then passes to MnO 2. he end-points are attained late, but in presence of telluric acid the end-point at MnO 2 stage corresonds to the theoretical value. Reduction at the MnO 4 -2 stage can be checked in presence of Ba +2 ns and good results obtained with 1–1.5 N NaOH.

Spectrophotometric Determination of Telluric Acid

Spectrophotometric Determination of Telluric Acid

Oxidation with alkaline permanganate using formic acid for the back-titration: Determination of quadrivalent tellurium and the redox potential of the teo 4-2/teo 3-2 system

On oxidizing Te +4 of concentration varying from ~ 0.02 — 0.09 N with KMnO 4, reduction of KMnO 4 proceeds in 0.1–4 N NaOH quantitatively to MnO 4 With a concentration of Te +4 — 4.585 · 1O -4 — 1.834 · 10 -5,of KMnO 4 = 2.096 · 10 -3 — 4.192 10 -5 M, and of NaOH = 3 —3.5, reduction of KMnO4 proceeds completely to manganate. Reduction of KMnO4 with Te+4 (4.63·10 -2 N) yields MnO4 with little Mn+3, without an inflection at the manganate state. In presence of telluric acid Mn+3 does not form and the reaction is quantitative. With Te +4 == 4.5–1.13·10 -3 an inflection corresponding to manganate occurs. The formal redox potential E f of the TeO 4 -2 TeO 3 -2 system decreases with increasing alkali concentration from 0.1–2.7 N, but becomes constant at higher alkalinities. E f is constant at Te +4= 0.09–0.02 N. Te +4 can be determined by mixing with KMnO 4 in 1.5–2 N NaOH and stirring the mixture at room temperature. Excess KMnO 4 is then determined with formate.

Preparation of Telluric Acid

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation of Telluric AcidH. J. Horner and Guy William Leonard Jr.Cite this: J. Am. Chem. Soc. 1952, 74, 14, 3694Publication Date (Print):July 1, 1952Publication History Published online1 May 2002Published inissue 1 July 1952https://doi.org/10.1021/ja01134a508RIGHTS & PERMISSIONSArticle Views130Altmetric-Citations6LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (180 KB) Get e-Alerts Get e-Alerts

Séparation quantitative des tellurites et tellurates; application a l'étude de l'échange isotopique

At pH 4.2 tellurous acid is precipitated and telluric acid remains in solution, the separation being quantitative. The isotopic exchange of tellurium between the two anions in acid solution, studied by this method of separation, is insignificant or extremely slow between 18 and 95° C.