System , hydrated

Furthermore, it is the system. Hydrate I/Hydrate II (or Anhydrous Salt), that possesses a definite pressure at a particular temperature this is independent of the relative amounts, but is dependent upon the nature of the two components in equilibrium. It is incorrect, therefore, to speak of the vapour pressure of a salt hydrate. ... 

In 0.1 M methanolic sodium hydroxide, the 6-chloropurine ketonu-cleoside 41b was cleaved after 30 min, whereas the theophylline derivative 41a was unaffected.26,27 The stability of the theophylline ketonu-cleoside 41a maybe explained by the establishment of a hydrogen bond between the 4 -gem-diol system (hydrate form of 41a) and the 2-keto group of theophylline. The assigned 4Ct (l) conformation would facilitate this bonding, whereas it could not occur with the 6-chloropurine derivative regardless of its conformation.27... 

In the presence of water, natural gas can, under the proper conditions of temperature and pressure, form hydrates. To the naked eye the hydrates are similar in appearance to snow and they can result in plugging of pipelines and flow systems. Hydrates can form at temperatures well above the freezing point of water. In the early days of pipelining natural gas under pressure, shutdowns of the lines during the winter months frequently were caused by plugging with hydrates. 

OSHA PEL TWA 0.1 mg(In)/m3 ACGIH TLV TWA 0.1 mg(In)/m3 SAFETY PROFILE A poison by subcutaneous route. It affects the liver, heart, kidneys, and the blood. Teratogenic effects. Inhalation of indium compounds may cause damage to the respiratory system. Hydrated indium oxide is a poison by... 

The characteristic feature of CM chondrules is the coexistence of roughly equal amounts of high-temperature anhydrous silicates (olivine and pyroxene) and low-temperature hydrous clay minerals. It is generally believed that the clay minerals were formed by aqueous alteration of the high-temperature phases, either in space or in the parent body. Figure 7 shows that the phyllosilicate matrix is systematically enriched in the heavy isotopes of oxygen, relative to the whole rock. The tie-lines between whole-rock compositions and matrix compositions have slopes of —0.7, implying that the water reservoir had a composition with more positive than the silicate reservoir. Clayton and Mayeda (1999) showed that the observed patterns can be accounted for with a simple closed-system hydration reaction at temperatures near 0°C,... 

Magnetics-activated drug delivery systems Sonophoresis-activated drug delivery systems Iontophoresis-activated drug delivery systems Hydration-activated drug delivery systems... 

The possibility of suspended transformation or the non-formation of the new phases must also be granted in the case where the vapour pressure is raised above that corresponding to the system hydrate— anhydrous salt (or lower hydrate)— vapour in this case the formation of the higher hydrate becomes a possibility, but not a certainty. Although there is no example of this known in the case of hydrated salts, the suspension of the transformation has been observed in the case of the compounds of ammonia with the metal chlorides (p. 76). Horstmann, for example, found that the pressure of ammonia in... 

In most cases the vapour pressure of a salt hydrate, i.e. the vapour pressure of the system hydrate—anhydrous salt (or lower hydrate)— vapour, is at all temperatures lower than that of the system anhydrous salt (or lower hydrate)—solution— vapour. This, however, is not a necessity and cases are known where the vapour pressure of the former system is, under certain circumstances, equal to or higher than that of the latter. An example of this is found in sodium sulphate decahydrate. 

With regard to sodium sulphate heptahydrate, the same considerations will hold as in the case of the decahydrate. Since at 24 the four phases heptahydrate, anhydrous salt, solution, vapour can coexist, the vapour-pressure curves of the systems hydrate—anhydrous salt— vapour (curve EB) and hydrate—solution— vapour (curve FB) must cut the pressure curve of the saturated solution of the anhydrous salt at the above temperature, as represented in Fig. 75 by the point B. This constitutes, therefore, a second quadruple point, which is, however, metastable. 

A fourth univariant system can be formed at B. This is the system hydrate—solution II,— vapour. The conditions for the existence of... 

The fourth curve, which ends at the quadruple point F, is that representing the vapour pressure of the system hydrate—solution I.— vapour (FH), This curve has been followed to a temperature of 0°, the pressure at this point being 113 cm. The metastable prolongation of GF has also been determined. Although, theoretically, this curve must lie below FH, it was found that the difference in the pressure for the two curves was within the error of experiment. 

As is evident from Fig. 86, three different bivariant systems are capable of existing in the area HFI which of these will be obtained will depend on the relative masses of the different phases in the univariant or invariant system. Thus, starting with a system represented by a point on the curve HF, diminution of volume at constant temperature will cause the condensation of a portion of the vapour, which is rich in sulphur dioxide since this would increase the concentration of sulphur dioxide in the solution, it must be counteracted by the passage of a portion of the hydrate (which is relatively poor in sulphur dioxide) into the solution. If, therefore, the amount of hydrate present is relatively very small, the final result of the compression will be the production of the system /, solution I.— vapour. On the other hand, if the vapour is present in relatively small amount, it will be the first phase to disappear, and the bivariant system hydrate—... 

Formula Chemical class Chemical type Na2Ca(U02)(C03)3-6H20 Crystal system Hydrated normal carbonate Mineral group -. A ,B (X03)p-xH20 where (m+n) p >1 1 Space group Trigonal Rutherfordine R3... 

Formula Chemical class Chemical type Mg2(C03)(0H)2-3I 0 Crystal system Hydrated carbonate with hydroxyl or halogen Mineral group A B (X0j)pZ, xH20 with (m+n) p = 2 1 Space group Monoclinic Hydromagnesite C2/m... 

---