Platinum vessel

Platinum is attacked under the following conditions, and such operations must not be conducted in platinum vessels ... 

All platinum vessels must be handled with care to prevent deformation and denting. Platinum crucibles must on no account be squeezed with the object of loosening the solidified cake after a fusion. Box-wood formers can be purchased for crucibles and dishes these are invaluable for re-shaping dented or deformed platinum ware. 

M Platinum crucibles and apparatus are the "silverware" of any good laboratory. Reactions under aggressive conditions can often only proceed in platinum vessels. 

He noted that It is only right to add that Madame Curie carried out a similar experiment, using a platinum vessel, instead of one of glass or silica, and obtained no lithium. But, he confidently adds, It requires considerable practice... to detect very small quantities of matter (1912, 157). 

The pyrolysis was studied using pressure of 50-200 torr over 350-410 °C in silicon and platinum vessels. The reaction in the platinum vessel was complex and will not be discussed. A probable mechanism for that in the silicon vessel is... 

FrepuratUm,—By heating calcic fluoride with sulphuric acid in a leaden or platinum vessel —... 

Fluorosulphonic Acid, FS02(OH).—This was first obtained by the addition of anhydrous hydrogen fluoride to sulphur trioxidc in a platinum vessel cooled in a freezing mixture, a slight excess of the halogen acid being used and removed subsequently by a current of dry carbon dioxide at about 30° C. 2... 

Heated to 120° C. in a closed platinum vessel, hydrogen fluoride and nitrogen sulphide unite to form a red liquid, which readily decomposes into its constituents. In the presence of traces of moisture, thionyl fluoride is formed. Dry hydrogen chloride reacts with nitrogen sulphide according to the equation 1... 

Fluorine perchlorate (b.p. —15.9°C, m.p. —167.5°C) is a gaseous explosive compound prepared for the first time by Fichter and Brunner [17] by the action of fluorine on perchloric acid solution. Rohrback and Cady [18] improved the method of preparing it by using 72% perchloric acid in a platinum vessel. 

Arsenic Pentafluoride, AsFs, may be prepared by the interaction of arsenic and fluorine in a platinum vessel,2 or by the action of bromine and antimony pentafluoride on arsenic trifluoride.3 The reagents should be dry, and if the reaction in the second case is carried out in a glass vessel, the apparatus should be in one piece and well dried. The bromine is added to the mixture of fluorides at - 20° C. and, after cooling in liquid air, the arsenic pentafluoride is obtained by heating on a water-bath at 55° C., the gas passing through a reflux condenser to a receiver surrounded by liquid air. The product contains bromine, which is removed by passing the gas over molten sulphur. 

Perfluoro(2-methylpropene) is the product of the pyrolysis of perfluoro(2-iodo-2-methylpropane) at 300°C in a platinum vessel.194 Perfluoro(4-methylpent-l-ene) was obtained as a minor product from perfluoro(l-iodo-4-methylpentane) in dimethylformamide at 80 C.195... 

COULOMETER. Also known as cnulombmeier, a device for the measurement of electric currem. Originally developed (1916) by the U.S. National Bureau of Standards, the silver coulometer consists of a small platinum vessel, acting as the cathode, into which a pure silver anode is immersed. An aqueous solution of silver nitrate (15% AgNO<. wl) of very high purity is used as the electrolyte, In use. both the quantity of silver deposited and the lime are carefully noted. These measurements permit a calculation of the average currcnl strength. 

Fusion with anhydrous potassium fluoride in a platinum dish is undoubtedly the simplest, most effective and reliable method available for the complete dissolution of a wide variety of siliceous materials. The potassium fluoride cake can then be transposed in the same container to a pyrosulfate fusion with rapid and complete volatilisation of both hydrogen fluoride and silicon tetrafluoride [54]. Except for a small quantity of barium sulfate, the pyrosulfate cake will dissolve completely in dilute hydrochloric acid. The resulting pyrosulfate fusion is one of the simplest and most effective methods available for rapid, complete and dependable dissolution of nonsiliceous materials, particularly high-fired oxides. This fusion has the distinct advantage that the flux can be obtained by simply adding easily purified alkali metal sulfates to sulfuric acid, and the fusion can be carried out in either borosilicate flasks or platinum vessels with very little contamination from either reagents or containers. 

Into a platinum vessel containing 7.1 g. of 7-(9,10-dihydro-2-phenan-thryl)-butyric acid is poured approximately 100 g. of liquid hydrogen fluoride. The acid dissolves readily on swirling, and the colored solution... 

Line spectra were first observed by J. von Fraunhofer, D. Brewster, and J. F. W. Herschel in the 1820s.180 In the ensuing decades a considerable amount of work was done on spectral phenomena prior to the demonstration by Bunsen and Kirchhoff in 1859 that line spectra could be used for qualitative chemical analysis. Accounts have appeared of the development of the spectroscope both prior and post Bunsen and Kirchhoff.181-183 Significant observations were undoubtedly made prior to 1860 by Stokes, Stewart, Fox Talbot, and others. The priority claims of Stokes, who recorded his ideas in some private letters to William Thomson, have been examined.184 The work of Bunsen and Kirchhoff did not owe a great deal to that of their predecessors, with the exception of the demonstration by W. Swan in 1856 that the almost omnipresent yellow line that coincided with Fraunhofer s dark solar D line was due to contamination by minute quantities of sodium salts.185 186 Platinum played an important role in the early development of spectroscopy. The metal was widely used to support the material in the flame, since it did not colour the flame itself. Bunsen ensured the purity of all his samples for spectrum analysis by recrystallization (sometimes up to fourteen times) in platinum vessels, thereby preventing contamination by minute quantities of salts that could be leached from glass vessels.187 Sharply contrasting views have been expressed about the failure of chemists prior to Bunsen to exploit spectroscopy.188-190... 

A trace of chlorine is usually found in the oxygen obtained by heating potassium chlorate in glass apparatus, a larger amount being obtained with Jena glass Ilian with eitliei soda or Bohemian combustion glass. When the chlorate is decomposed in platinum vessels, however, chlorine is either not evolved, or only in infinitesimal quantities whether at atmospheric or under reduced pressure.4... 

When boiled with sulphur in the presence of oxygen in platinum vessels, water yields hydrogen sulphide and sulphuric acid.2... 

Lowenstem s3 method consisted in passing a slow current of water-vapour through a tube heated to various temperatures, and containing a closed platinum vessel, P, attached to a manometer, M (fig. 45). The... 

Both Pd and Pt are rapidly attacked by fused alkali oxides, and especially by their peroxides, and by F2 and Q2 at red heat. In using platinum vessels or other equipment it should be noted that the metal reacts with elemental P, Si, Pb, As,... 

There is often no need for an absolute determination of vapor pressure. The solvent vapor pressure can be determined simply by setting up a closed system that contains a solution of large volume having an already known solvent activity. The unknown solution will change its concentrations (and hence its weight) until its solvent activity is the same as that of the reference system, which is known. Great accuracy in the weighing is essential and one should use platinum vessels to minimize possible dissolution. 

Like molybdenum and tungsten, vanadium forms a variety of nonstoichiometric oxides with the alkali metals and other cations, for example, Cu+, Ag+, Zn+, or Al+, which have bronze-like properties. " These compounds can be made by heating appropriate mixtures of V2O5 and the desired alkali metal carbonate or oxide in platinum vessels under argon at 700-800 °C and then cooling slowly over... 

In a method used by Thomsen the given liquid, e.g. a solution, was used as the calorimeter liquid and heat given to it by the combustion of hydrogen or by a chemical reaction (e.g. the dilution of sulphuric acid, in a vessel immersed in the liquid. A known mass of heated solid can also be immersed in the liquid in a calorimeter. Schiff enclosed the liquid in a platinum vessel of cross-shaped section, containing a thermometer. This was heated to a given temperature and then put into the calorimeter, and stirred round in the water. The liquid was in layers only 1 cm. thick and a rapid equalisation of temperature was thus ensured. Schlesinger heated the liquid electrically and deduced the rise in temperature from the measured increase in volume and the coefficient of expansion. Specific heats of liquids at low temperatures ca,n be determined by a modification of the Nernst calorimeter, in which the liquid in a small steel vessel contained in a... 

Tungsten Hexafluoride, WFg, is obtained by the action of anhydrous hydrogen fluoride upon tungsten hexaehloride in platinum vessels, or by the interaction of antimony peiitafluoride with the hexa-chloride. It is a solid at low temjreratures just above 0° C. it sublimes to a heavy gas which fumes in moist air it reacts with water with production of tungstic acid. It attacks both glass and mercury by alkalies it is decomposed, and with alkali fluorides it forms double salts. 

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