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1.
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. 相似文献
2.
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. 相似文献
3.
In the gravimetric determination of neodymium, the hydroxide should be heated to above 608° and the oxalate decahydrate to above 813°, in order to ensure a correct weight. The anhydrous oxalate can be weighed after heating between 290° and 350°. 相似文献
4.
With the help of the CHEVENARD thermobalance, the authors have traced the pyrolysis curves of the precipitates which are used for the gravimetric determination of mercury. The methods in which a period?ate, a molybdate, a vanadate, cupferron, and 2-chloro-7-methoxy-5-thiolacridine are used, have been rejected. Only four methods out of the 21 proposed for the precipitation of metallic mercury have been considered. The dissociation of mercuric nitrate has no interest from the analytical
Réactif précipitant | Forme de pesée | Limites de température |
Electrolyse | Hg | <70° |
Zinc + Iodure de potassium | Hg | <72° |
Hydrazine | Hg | <55° |
Acide hypophosphoreux | Hg | <71° |
Acide nitrique | HgO | 100°–200° |
Acide chlorhydrique | Cl2Hg2 | <130° |
*Iodure de potassium | I2Hg | 45°–88° |
*Iodate de potassium | (IO3)2Hg2 | <175° |
Periodate de potassium | (IO3)2Hg2 | <175° |
Sulfure d'ammonium | SHg | <109° |
*Thiosulfate de sodium | SHg | 75–220° |
Arséniate disodique | (AsO4)2Hg3 | 45–418° |
*Thiocyanate de cobalt | [Hg(SCN)4]Co | 50–200° |
Thiocyanate de zinc | [Hg(SCN)4]Zn | <270° |
*Chromate de potassium | CrO4Hg2 | 52–256° |
Chromate de potassium ammoniacal | CrO4Hg2 | 52–256° |
*Bichromate d 'ammonium + Pyridine | Cr2O7[Hg(C5H5N)2] | 56–66° |
*Sel de Reinecke | [Cr(CNS)4(NH3)2]2Hg | 77–158° |
Molybdate alcalin | [Cr(CNS)4(NH3)2]2Hg | 77–158° |
Tungstate alcalin | WO3 | >880° |
Vanadate alcalin | WO3 | >880° |
Iodure de cadmium ammoniacal | (HgI3)2[Cd(NH3)4] | <69° |
Iodure de potassium + Sulfate de cuivre + Ethylène diamine | [HgI4][Cu En2] | à 20° |
*Iodure de potassium + Sulfate de cuivre + Propylène diamine | [HgI4][Cu Pn2] | <157° |
Acide oxalique | C2O4Hg2 | <100° |
Anthranilate de sodium | (C6H6O2N)2Hg | <113° |
Pyridine | Cl2Hg(C5H5N) | <113° |
Dithiane | Cl2Hg.C4H8S2 | <97° |
*Chlorure de cuivre-biguanide + iodure de potassium | [HgI4][Cu(C2N5H7)2] | 60–175° |
Cupferron | [HgI4][Cu(C2N5H7)2] | 60–175° |
*Thionalide | (C12H10ONS)2Hg | 90–169° |
Chloro-2 méthoxy-7 thiol-5 acridine | (C12H10ONS)2Hg | 90–169° |
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° |
Hydroxide by ammonium hydroxide | 408° |
Hydroxide by ammonia | 400° |
Hydroxide by urea | 475° |
Hydroxide by aniline | 546° |
Hydroxide by sulpliitc | 813° |
Hydroxide by tannin | 520° |
Cupfcrron | 745° |
Camphoratc | 478° |
Dibromo-oxinate | 817° |
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