Sublimate this

In addition to dry ice, mothballs and certain solid air fresheners also go through the process of sublimation. The reverse of sublimation is deposition — going directly from a gaseous state to a solid state 

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Sublimation. This is a most useful process for small-scale work as the losses are comparatively small. This can be performed (a) In a long narrow tube sealed at one end. The material is shaken to the closed end of the tube, which is then inserted horizontally in a metal-heating block (Fig. 50) (b) In the cold-finger device (Fig. 35, p. 62)-... 

Sublimation.—This is a valuable means for the purification of many organic substances and is admirably adapted for small scale work since losses are generally small. Sublimation may be carried out either at atmospheric pressure or under reduced pressure. The apparatus shown in Fig. XII, 2, 20 is simple and effective the sublimate is collected on the cold finger condenser. 

Many mercury compounds are labile and easily decomposed by light, heat, and reducing agents. In the presence of organic compounds of weak reducing activity, such as amines (qv), aldehydes (qv), and ketones (qv), compounds of lower oxidation state and mercury metal are often formed. Only a few mercury compounds, eg, mercuric bromide/77< 5 7-/7, mercurous chloride, mercuric s A ide[1344-48-5] and mercurous iodide [15385-57-6] are volatile and capable of purification by sublimation. This innate lack of stabiUty in mercury compounds makes the recovery of mercury from various wastes that accumulate with the production of compounds of economic and commercial importance relatively easy (see Recycling). 

Sublimation. This process is employed to separate volatile substances from non-volatile impurities. Iodine, arsenic(III) oxide, ammonium chloride and a number of organic compounds can be purified in this way. The material to be purified is gently heated in a porcelain dish, and the vapour produced is condensed on a flask which is kept cool by circulating cold water inside it. 

While A

metal-water interactions are better probed by thermal desorption spectroscopy (TDS) in which heat is used to detach molecules from a surface. TDS data are in parallel with A (and AX) data. This is illustrated in Fig. 19.35 The spectrum of Ag(110) shows only one peak at 150 K, corresponding to ice sublimation. This means that Ag-H20 interactions are weaker than H20-H20 interactions (although they are still able to change the structure of the... 

Distillation, sublimation This can be used to remove the metals from Ta (from crucibles, etc. dissolved by the molten R and re-precipitated). The volatile R (Sm, Eu, Dy, Ho, Er, Tm, Yb, Sc) are also purified from C, N, O (present as carbides, nitrides, oxides). Gschneidner (1980) underlined that, in order to obtain high purity, a very high vacuum (10 8-10 9mmHg) and a slow sublimation rate must be maintained during the distillation process. 

Chemical vapor deposition (CVD) is a process whereby a thin solid film is synthesized from the gaseous phase by a chemical reaction. It is this reactive process that distinguishes CVD from physical deposition processes, such as evaporation, sputtering, and sublimation. This process is well known and is used to generate inorganic thin films of high purity and quality as well as form polyimides by a step-polymerization process. Vapor deposition polymerization (VDP) is the method in which the chemical reaction in question is the polymerization of a reactive species generated in the gas phase by thermal (or radiative) activation. 

Table 6 contains the experimental values r and /jt for the molecules SrO and BaO. There is no difference of opinion as to the quantization 7 [M2+, 0 ]n of these oxides in the crystalline state and there is, a priori, no reason to believe that this quantization changes on sublimation. This correlation between solid and vapor appears to be more justifiable than that of the ground state of the molecule with those of the atoms M and O, even more so that the latter would require two unpaired electrons not observed for the alkaline earth oxide molecules. 

The desolvation of the droplets is usually completed in the preheating zone. The mist of salt clotlets then fuses and evaporates or sublimes. This is critically dependent on the size and number of the particles, their composition and the flame mixture. As the absolute concentration of analyte in the flame is very small (< lO- atm), the saturated vapour pressure may not be exceeded even at temperatures below the melting point. 

We are dealing with the case where a < 0. In consequence, there is a possibility of surface enrichment if the bond strength of a BB pair is smaller than that of an AA pair. Here we touch upon the rule that surface enrichment occurs in the component with the lower heat of sublimation. This effect can, however, be counterbalanced if a is highly negative. If Eq. (5) is not satisfied, there will be no surface enrichment, even if T = 0. 

Sublimation. This involves heating a solid until it passes directly from the solid phase into the gaseous phase. The reverse process, when the vapor goes back to the solid phase without a liquid state in between, is called condensation or deposition. Some solids which sublime are iodine, caffeine, and paradichlorobenzene (mothballs). 

Some textbooks recommend the removal of ammonium salts simply by sublimation. This can be done by first evaporating the acidified filtrate on a water bath, and then heating the dry residue at a higher temperature, until the white fumes of ammonium salts cease to appear. It is much easier however to remove ammonium salts with concentrated nitric acid, as described in Table V.12, when a chemical decomposition takes place ... 

HUMIDITY OF THE STONE — This is also the Mercury, for the Mercury is a dry water which does not wet the hands, and attaches or clings only to that which is of its own nature. To impart its Humidity to the Stone is to perform the work of Imbibition that is to say, to continue the regimen of the Philosophical Fire, which sublimes this Humidity to the summit of the Vase, whence Imbibition is performed of itself, the same Humidity returning upon the earth at the bottom. 

The process of Parylene polymerization is presented schematically in Figure 2.1 for Parylene N (no substituent on phenyl ring). Parylene dimer is heated until it sublimes. This dimer vapor passes through a high-temperature pyrolysis zone (about 650°C) where it cracks and becomes monomer vapor. The monomer polymerizes and polymer is deposited on surfaces in the deposition chamber, of which temperature should be less than 60°C. Parylene C deposition, which is typically carried out at room temperature and completed in vacuum, is a process with no solvents, no... 

Along the line AB, solid is in equilibrium with vapor. If the pressure is decreased below the line AB, the solid will sublime. This relationship is the basis of freeze-drying foods, such as those shown in Figure 25. The food is frozen, and then a vacuum is applied. Water sublimes, which dehydrates the food very quickly. The food breaks down less when water is removed at the low temperature than when water evaporates at normal temperatures. 

The spirit, therefore, by help of the water and the soul, is drawn forth from the bodies themselves, and the body is thereby made spiritual for that at the same instant of time, the spirit, with the soul of the bodies, ascends on high to the superior part, which is the perfection of the stone and is called sublimation. This sublimation, is made by things acid, spiritual, volatile, and which are in their own nature sulphureous nd viscous, which dissolves bodies and makes them to ascend, and be changed into air and spirit, and in this sublimation, a certain part of our said first water ascends with... 

Sublimation.—This process is of special value when it is desired to separate a solid which is volatile from substances which do not vaporize readily. It generally yields a very pure substance, but it often leads to loss. 

The results we obtained at 77 K, a temperature more appropriate to the jovian moons, are qualitatively and quantitatively the same as those at 16 K. Moreover, after implantation, we warmed the samples and obtained spectra at progressively higher temperatures Carbon dioxide is still there at 140 K when water ice completed the crystallization process, and it remains trapped until water is lost by sublimation. This gives us confidence that our findings can be extrapolated to environments with a large range of temperatures. " ... 

A drug solution is first frozen at atmospheric pressure, and then water is removed by a reduction of pressure in the lyophilizer chamber, coUecting the water as ice on a condenser. Samples are placed in glass vials and frozen, either before being put in the lyophilizer or on the lyophilizer shelves. The samples contain ice crystals, tmfrozen water, amorphous solids (including the therapeutic protein), and crystalline additives. Pressure is reduced, and the ice crystals sublime. This constitutes the primary drying. 

A Recirculating Inert Liquid Heat Removal System. While standard inert atmosphere gloveboxes may be used to perform ambient temperature reactions, the lack of a facility for localized heat removal (as provided externally be running tap water) precludes all syntheses requiring reflux, distillation, or sublimation. This limitation may be eliminated by the installation of a recirculating liquid heat exchange system. 

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