Sur la stabilité thermique des étalons analytiques. XI

Résumé Nous avons étudié par thermogravimétrie et par spectrophotométrie infrarouge, entre 6 et 15, douze substances nouvelles proposées pour étalons en chimie analytique. Le chlorure de magnésium et d'ammonium, l'hydrogénocarbonate d'ammonium et le fluorure d'ammonium paraissent d'emploi douteux pour préparer avec certitude une liqueur titrée.

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Summary Twelve new substances suggested as standards in analytical chemistry have been investigated by thermogravimetry and infrared spectrography, between 6 and 15. Magnesium ammonium chloride, ammonium bicarbonate and ammonium fluoride seem to be of doubtful value for the accurate preparation of a standard solution.

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Zusammenfassung Zwölf zur Herstellung von Urtiterlösungen neu vorgeschlagene Substanzen wurden thermogravimetrisch und infrarotspektrophotometrisch zwischen 6 und 15 geprüft. Magnesium-Ammoniumchlorid, Ammoniumhydrogencarbonat und Ammoniumfluorid scheinen für diesen Zweck von zweifelhaftem Wert zu sein.

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Pour le dixième mémoire de cette série, voir Mikrochim. Acta [Wien]1962, 268.     

Sur la stabilité thermique des étalons analytiques. XIII

Résumé L'examen de 12 substances proposées comme étalons révèle que le chlorure et l'iodure de zinc doivent être manipulés à l'abri de l'humidité atmosphérique après séchage au-dessous de 60°; l'acétate et le sulfate de zinc issus d'un flacon neuf peuvent être pesés directement; le fluorure de sodium est parfaitement stable jusqu'à 850°; le carbonate de sodium et de potassium peut être utilisé tel quel mais il est préférable de le déshydrater entre 250 et 700°; l'hydrogénosulfate de potassium est hygroscopique et doit être séché avant pesée, sans dépasser 200°; l'hexaméthylènetétramine, le morpholine N-dithiocarbonate de morpholinium, le tétraphénylborure de sodium sont bien secs; il ne faut pas dépasser 150° pour obtenir la chloramine T anhydre. Les auteurs précisent la différence de comportement entre l'hydrogénosulfate et le pyrosulfate de potassium.

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Summary Study of 12 materials suggested as standards reveals that zinc chloride and iodide should be handled away from the atmospheric moisture after drying below 60°. Zinc acetate and sulfate freshly taken from a new bottle may be weighed immediately. Sodium fluoride is perfectly stable up to 850°. Sodium-potassium carbonate may be used just as they are but it is preferable to dry them between 250 and 700° before weighing. Potassium hydrogen sulfate is hygroscopic and should be dried prior to weighing but not above 200°. Hexamethylenetetramine, morpholinium morpholine-N-dithiocarbonate, sodium tetraphenyl boron are quite dry. Chloramine T can be obtained anhydrous without going higher than 150°. The difference in behavior between potassium hydrogen sulfate and pyrosulfate is stated precisely.

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Zusammenfassung Die Untersuchung 12 als Standard vorgeschlagener Substanzen ergab, daß Zinkchlorid und -jodid nach Trocknung unterhalb 60° zur Entfernung der Luftfeuchtigkeit verwendet werden können. Zinkacetat und -sulfat können nach Entnahme aus einer frischen Packung direkt eingewogen werden. Natriumfluorid ist bis 850° stabil. Natrium-Kaliumcarbonat kann wohl unmittelbar verwendet werden, doch ist es besser, es zwischen 250 und 700° zu entwässern. Kaliumhydrogensulfat ist hygroskopisch und muß vor dem Einwägen getrocknet werden, ohne die Temperatur über 200° zu steigern. Hexamethylentetramin, morpholin-N-dithiocarbonsaures Morpholinium und Natriumtetraphenylborat sind hinreichend trocken. Um wasserfreies Chloramin T zu erhalten, darf man nicht über 150° gehen. Der Unterschied im Verhalten von Kaliumhydrogensulfat und -pyrosulfat wird genau angegeben.

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Pour le 12ème mémoire de cette série, voir Mikrochim. Acta [Wien]1963, 348.

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En l'honneur du ProfesseurA. A. Benedetti-Pichler.     

Sur la stabilité thermique des étalons analytiques. X

Résumé Nous avons examiné douze nouveaux corps minéraux et organiques devant servir à faire des liqueurs titrées. La strontiane et le nitrate d'aluminium paraissent d'emploi douteux dans les travaux de précision.

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Summary We have examined twelve inorganic and organic compounds with respect to their use as standard solutions. Strontium oxide and aluminium nitrate appear to be of doubtful value in precise work.

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Zusammenfassung Zwölf weitere anorganische und organische Stoffe wurden auf ihre Eignung als Urtitersubstanzen geprüft. Strontiumoxyd und Aluminiumnitrat eignen sich für exakte Bestimmungen nicht.

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En l'honneur du ProfesseurF. Feigl, pour son 70^e anniversaire.     

Sur la stabilité thermique des étalons analytiques. VI

Twelve substances, which can be used as standards in volumetric analysis were studied, special attontion being paid to the pyrolysis of the three iron salts among these substances.     

Sur la stabilité thermique des étalons analytiques.iv

In this fourth article on standards the authors have plotted the thermolysis curves and ascribed the infrared absorption spectra of 12 substances in the solid state. These substances can be used in various instances for making standard solutions for chemical analysis.     

Sur la stabilité thermique des étalons analytiques. XIV

Résumé L'étude par thermogravimétrie et spectrophotométrie d'absorption infrarouge de 12 substances pouvant servir comme étalons en chimie analytique, révèle que le sulfate de lithium monohydraté, le bichromate de sodium bihydraté, le cobaltinitrite de sodium, le chlorure d'hydrazinium, le sulfate d'hydrazinium, la méthylglucamine et l'acidel-ascorbique sont d'un emploi sûr; il est préférable d'utiliser le chlorure de calcium, le séléniate de sodium, le chromate de sodium et le sulfate de manganèse sous forme anhydre; l'acétate de nickel tétrahydraté ne peut servir directement.

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Summary Thermogravimetric and infrared absorption spectrophotometric studies of twelve materials that may serve as standards in chemical analysis show that the following are reliable: lithium sulfate monohydrate, sodium bichromate dihydrate, sodium cobaltinitrite, hydrazinium chloride, hydrazinium sulfate, methylglucamine, ascorbic acid. It is better to use the following in the anhydrous state: calcium chloride, sodium selenate, sodium chromate, manganese sulfate. The tetrahydrate of nickel acetate cannot be employed directly.

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Zusammenfassung Thermogravimetrisch und infrarot-spektrophotometrisch wurden zwölf Substanzen untersucht, die in der analytischen Chemie als Eichsubstanzen verwendet werden. Diese Untersuchungen ergaben, daß Lithiumsulfatmonohydrat, Natriumbichromat-Dihydrat, Natriumnitritokobaltiat, Hydrazinchlorhydrat, Hydrazinsulfat, Methylglukamin und L-Ascorbinsäure mit Sicherheit verwendet werden können. Calciumchlorid, Natriumseleniat, Natriumchromat und Mangansulfat verwendet man besser in wasserfreier Form. Nickelacetat-Tetrahydrat ist zur unmittelbaren Verwendung ungeeignet.

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Pour le 13ème mémoire de cette série, voir Mikrochim. Acta [Wien]1964, 202.     

Sur la stabilité thermique des étalons analytiques. I

The authors have studied the thermal stability of 12 substances used as standards in analytic. chemistry and have recorded their infra-red spectra; They observe large irregularities in the Water content of hydrated salts, especially in the case of barium chloride. They recommend in gener the anhydrous substance and give the minimum temperature necesary for obtaining it.     

Sur la stabilité thermique des étalons analyt1ques. ii

In this second investigation of 12 standard solutions, used in various titrations in analytical chemistry, we have continued studies on the thermal behaviour and have obtained the infrared absorption spectrum with regard to identification of substances and their impurities.     

Sur quelques étalons de pH faciles à préparer

Résumé L'étalonnage des électrodes de verre, dans la pratique courante, est grandement facilité par l'emploi de solutions tampons étalons préparées rapidement en dissolvant, à saturation, des sels purs. Au bitartrate préconisé parLingane, nous ajoutons le carbonate de lithium, et le borax (dont le coefficient de température est inférieur à celui du borax non saturé), utilisables en milieu alcalin.

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Summary The standardization of glass electrodes in routine practice is greatly facilitated by the use of buffer solutions which are rapidly prepared by dissolving pure salts to the saturation point. To bitartrate, recommended byLingane, we add lithium carbonate, and borax (whose temperature coefficient is less than that of unsaturated borax). These can be employed in alkaline surroundings.

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Zusammenfassung Die Eichung von Glaselektroden für die laufende Praxis wird wesentlich vereinfacht durch die Verwendung von Standard-Puffer-Lösungen, die durch Sättigung mit reinen Salzen rasch herstellbar sind. Dem vonLingane vorgeschlagenen Bitartrat setzen wir Lithiumcarbonat und Borax zu (dessen Temperaturkoeffizient geringer ist als in nicht gesättigten Boraxlösungen). Diese Pufferlösung eignet sich für das alkalische Gebiet.

     

Étude numérique de la stabilité des écoulements de convection naturelle dans des espaces annulaires horizontaux de faible épaisseur

The mechanisms driving the multiplicity of multicellular natural convective flows found at the top of narrow horizontal air-filled concentric annuli (the inner cylinder temperature exceeding the outer) are considered. For radius ratio less than R = 1.20, the base flow undergoes an imperfect bifurcation. The two stable branches are characterised.     

Sur la thermogravimétrie des précipites analytiques : Dosage du strontium

By means of the CHEVENARD thermobalance, the authors have traced the curve of pyrolysis of the following strontium compounds; sulphate, fluoride, iodate, arsenate, carbonate, chromate, oxalate and tartrate. They have determined the temperatures at which the dissociation of the sulphate and chromate begins to occur. They recommend as excellent the weighing of strontium in the form of the iodate and para periodate.     

Sur la thermogravimétrie des precipités analytiques : Dosage du Rubidium

With the aid of the chevenard thermobalance the authors have traced the pyrolysis curve of the following compounds of rubidium : chloride, perchlorate, sulphate, hexanitritocobaltate, hexachlorostannate, hexachloroplatinate; they have determined the ternperatures of commencement of dissociation of these substances, shown the different behaviour of the neutral and the acid sulphates, and demonstrated that the hexamtritocobaltate (colialtinitrite) cannot be employed for gravimetric analysis and the hexachlorostannate (stannichloride) requires a special method of preparation in order to give accurate results.     

Sur la thermogravimétrie des précipités analytiques: Dosage du thallium

With the help of the chevenard thermobalance the authors have established the following limits for drying or ashing, of thallium derivatives before weighing. Trioxide prepared chemically: 126° to 230°; trioxide prepared electrolytically: 156° to 283°; chloride: 56° to 425°; iodide. 70° to473°; sulphate : 92° to 355°; luteocobaltic thalliumchloride :50° to 210°; chromate : 97° to 745°; hexachloroplatinate: 65° to 155°; thionalide complex: 69° to 156°; mercaptobenzothiazole complex: 52° to 217°.The two trioxides which have been prepared show signs of a transitory formation of 3Tl₂O₃.Tl₂O on heating, but above 600° they behave differently. The chemically prepared trioxide shows two ranges of thermal stability.     

Sur la thermogravimétrie des précipités analytiques : Dosage du zirconium

With the help of the chevenard thermobalance, the authors have traced and examined the thermolysis curves of the precipitates proposed for the determination of zirconium. The methods in which picric acid, potassium iodate, ammonium arsenate and oxine are used, have been rejected; those in which ammonia, aniline, diethylaniline and in particular mandelic acid are used, are recommended for the automatic determination of zirconium. Zirconium hydroxide can be prepared in a pure state by means of aniline, while various other reagents smoothly afford zirconyl hydroxide. The problem of reduction of zirconium by pyrolysis of its arsenic(V) derivatives has been posed but not solved.     

Sur la thermogravimétrie des précipités analytiques: Dosage du chrome

By means of the CHEVENARD thermobalance, the precipitates used for the determination of chromium have been investigated and the following limits of temperature established:

     

18.

Sur la thermogravimétrie des précipités analytiques : Dosage du sodium     

Thérèse Duval  Clément Duval 《Analytica chimica acta》1948

This thermogravimetric study has enabled the authors to specify a large number of points of detail in connection with the correct determination of sodium. Their attention has been particularly directed to the triple acetates, which they recommend should be weighed only in the form of pyro-uranates. The method of ball, less classical than the others, would merit greater attention on the part of analysts.     

19.

Sur la thermogravimétrie des précipités analytiques : Dosage du Potassium     

Thérèse Duval  Clément Duval 《Analytica chimica acta》1948

The authors have studied the pyrolysis of 10 compounds of potassium and defined the limits of temperature between which they must dried in order to be determined accurately by weighing. Apart from the hexanitritocobaltate, the use of which is restricted to volumetric and coloimetric analysis, it can be said that the 9 other salts examined are well suited to the determination of potassium, the hydrontertrate, used within the limits prescribed by the authors, merits special attention.     

20.

Sur la thermogravimétrie des précipités analytiques : Dosage du bismuth     

Clément Duval 《Analytica chimica acta》1951

With the help of the CHEVENARD thermobalance, the authors have traced the 36 pyrolysis curves of the precipitates used for the gravimetric determination of bismuth. They have retained 15 methods suitable for the automatic determination. In particular, they recommend the methods using thionalide, phenyldithiobiazolonethiol, and phenylaisonic acid. A critical examination of the methods selected for the gravimetric determination of bismuth seems to show that MAJUMDAR's phenyldithiobiazolonethiol is the best available at present. The authors suggest the rejection (because constant weight is not reached, or because quantitative precipitation does not occur, or because the formula of the compounds formed does not tally with the one presumed) of the precipitation methods using glucose, hypophosphorous acid, iodic acid, hydrogen sulphide, sodium thiosulphate, potassium bichromate, ammonium molybdate, potassium chromic thiocyanate, hexamethylenetetramine, pyrogallol, gallic acid, oxine, antipyrine-methyleneamine, and α-naphthoquinoline.     

Precipitating reagent	Form in which weighed	Temperature limits
Ammonium hydroxide (to a chromic salt)	Cr2O3	> 812°
Ammonium hydroxide (to chromic acid)	Cr2O3	> 188°
Ammoniac (gas)	Cr(OH)3	440–475°
Ammoniac (gas)	Cr2O3	> 845°
Aniline	Cr2O3	> 830°
Hydroxylamine	Cr2O3	> 850°
Thiosemicarbazide	Cr2Oa3.H2O	380–410°
Thiosemicarbazide	Cr2O3	> 475°
Potassium cyanate	Cr2O3.H2O	320–370°
Potassium cyanate	Cr2O3	> 473°
Ammonium nitrite	Cr2O3	> 880°
Potassium iodo-iodate	Cr2O3	> 850°
Disodium phosphate	CrPO4	> 946°
Silver nitrate	Ag2CrO4	92–812°
Mercurous nitrate	Hg2CrO4	82–256°
Mercurous nitrate	Cr2O3	> 671°
Barium nitrate	BaCrO4	< 60°
Lead nitrate	PbCrO4	91–904°
8-Hydroxyquinoline	Cr(C9H6ON)3	70–156°
8-Hydroxyquinoline	Cr2O3	> 500°

Sur la thermogravimétrie des précipités analytiques : Dosage du sodium

This thermogravimetric study has enabled the authors to specify a large number of points of detail in connection with the correct determination of sodium. Their attention has been particularly directed to the triple acetates, which they recommend should be weighed only in the form of pyro-uranates. The method of ball, less classical than the others, would merit greater attention on the part of analysts.     

Sur la thermogravimétrie des précipités analytiques : Dosage du Potassium

The authors have studied the pyrolysis of 10 compounds of potassium and defined the limits of temperature between which they must dried in order to be determined accurately by weighing. Apart from the hexanitritocobaltate, the use of which is restricted to volumetric and coloimetric analysis, it can be said that the 9 other salts examined are well suited to the determination of potassium, the hydrontertrate, used within the limits prescribed by the authors, merits special attention.     

Sur la thermogravimétrie des précipités analytiques : Dosage du bismuth

With the help of the CHEVENARD thermobalance, the authors have traced the 36 pyrolysis curves of the precipitates used for the gravimetric determination of bismuth. They have retained 15 methods suitable for the automatic determination. In particular, they recommend the methods using thionalide, phenyldithiobiazolonethiol, and phenylaisonic acid. A critical examination of the methods selected for the gravimetric determination of bismuth seems to show that MAJUMDAR's phenyldithiobiazolonethiol is the best available at present. The authors suggest the rejection (because constant weight is not reached, or because quantitative precipitation does not occur, or because the formula of the compounds formed does not tally with the one presumed) of the precipitation methods using glucose, hypophosphorous acid, iodic acid, hydrogen sulphide, sodium thiosulphate, potassium bichromate, ammonium molybdate, potassium chromic thiocyanate, hexamethylenetetramine, pyrogallol, gallic acid, oxine, antipyrine-methyleneamine, and α-naphthoquinoline.