Thermodynamic classification

The energy or power required by any separation process is related more or less directly to its thermodynamic classification. There are, broadly speaking, three general types of continuous separation processes reversible, partially reversible, and irreversible. 

In Refs. [24,25], a two-dimensional thermodynamic classification of nonionic monomers was proposed, which took into account three possible preferential locations of a monomer unit (location either in the hydrophilic or the hydrophobic phase or at the interface between them). The proposed classification incorporates gradations by affinity to polar and nonpolar phases and by interfacial activity (Fig. 3). 

Both kinetic and thermodynamic classifications of metal-nitrogen complexes have been proposed. The former gives systems that are either coordinatively inert or labile see Coordinatively Inert Labile Complexes), with inert being defined as fhose that allow geometric isomers see... 

Matsuyama, H., Nishimura, H. (1977). Topological and Thermodynamic Classification of Ternary Vapor-Liquid Equilibria. J. Chem. Eng. Japan., 10,181-7. 

In the modern classification scheme, phase transitions are divided into two broad categories, named similarly to the Ehrenfest classes transitions with latent heat on one hand and transitions without latent heat on the other hand. This is a thermodynamic classification. 

We will now combine the preceding thermodynamic classification with that of the phenomena and their effects. For that we will, except contrary specification, take into account only two external physical variables, pressme and temperature, and thus p = 2. 

It is possible to indicate by thermodynamic considerations 24,25,27>, by spectroscopic methods (IR28), Raman29 , NMR30,31 ), by dielectric 32> and viscosimetric measurements 26), that the mobility of water molecules in the hydration shell differs from the mobility in pure water, so justifying the classification of solutes in the water structure breaker and maker, as mentioned above. 

Ramsdellite is thermodynamically unstable toward a transformation into the stable ft -modification. Hence, it is rarely found in natural deposits. Natural ramsdellite has a stoichiometry close to the composition of Mn02 and can be considered another true modification of manganese dioxide. Attempts to synthesize ramsdellite in the laboratory usually lead to materials of questionable composition and structural classification. It is very likely that synthetic ramsdellite materials are more or less well-crystallized samples of the y-modification that will be described in more detail below. 

A classification of dispersed systems on this basis has been worked out by Pawlow (30) (1910), who introduces a new variable called the concentration of the dispersed phase, i.e., the ratio of the masses of the two constituents of an emulsion, etc. When the dispersed phase is finely divided the thermodynamic potential is a homogeneous function of zero degree in respect of this concentration. 

A distinction between a solid and liquid is often made in terms of the presence of a crystalline or noncrystalline state. Crystals have definite lines of cleavage and an orderly geometric structure. Thus, diamond is crystalline and solid, while glass is not. The hardness of the substance does not determine the physical state. Soft crystals such as sodium metal, naphthalene, and ice are solid while supercooled glycerine or supercooled quartz are not crystalline and are better considered to be supercooled liquids. Intermediate between the solid and liquid are liquid crystals, which have orderly structures in one or two dimensions,4 but not all three. These demonstrate that science is never as simple as we try to make it through our classification schemes. We will see that thermodynamics handles such exceptions with ease. 

For electrolytes where dissociation is extensive, but not complete, the classification is somewhat arbitrary, and the electrolyte can be considered to be either strong or weak. Thermodynamics does not prevent us from treating an electrolyte either way, but we must be careful to designate our assignment because the choice of standard state is different for a strong electrolyte and a weak electrolyte. Assuming that an electrolyte is weak requires that we have some nonthermodynamic procedure for distinguishing clearly between the dissociated and undissociated species. For example, Raman spectroscopy... 

The vast number of thermodynamically possible reactions obtained by permuting oxidants and reductants within the scope of this review present major problems of classification and selection. To only a limited extent is the modernity or detail of a paper indicative of its relevance, some of the definitive papers having been published before 1950. Discussion has been concentrated, therefore, at points where a kinetic investigation of a reaction has resulted in a real advance in our understanding both of its mechanism and of those of related reactions, and work which has been more of a confirmatory nature will not receive comparable consideration. Detailed reference to products, spectra, etc. will be made only when the kinetics produce real ambiguities. 

Various secondary sources of safety data are now listing this as an explosive. I can find no primaiy source for this classification, which seems very improbable. Simple minded use of many computational hazard prediction procedures would show thermodynamically that this compound, like most lower amines, could hypothetically convert to alkane, ammonia and nitrogen with sufficient energy (about 3 kJ/g) to count as an explosion hazard. This reaction is not known to happen. (Simple minded thermodynamicists would rate this book, or computer, and its reader as a severe hazard in an air environment.) Like other bases, iminobispropylamine certainly sensitises many nitro-explosives to detonation. It is used experimentally to study the effect, which may have found technical exploitation and, garbled, could have led to description of the amine as itself an explosive. 

Clarke-Othmer process, for acetic acid-water for ethanol separation, 5 834 Claros Diagnostics, 26 976 Class 4A inert ingredients, 14 126 Classes A-C radioactive waste, 25 853 disposal of, 25 857 Classical least squares, 6 39-41 Classical thermodynamics, 24 641-642 Classification bauxite, 2 353... 

---