Thermodynamic solubility

CHEOPS is based on the method of atomic constants, which uses atom contributions and an anharmonic oscillator model. Unlike other similar programs, this allows the prediction of polymer network and copolymer properties. A list of 39 properties could be computed. These include permeability, solubility, thermodynamic, microscopic, physical and optical properties. It also predicts the temperature dependence of some of the properties. The program supports common organic functionality as well as halides. As, B, P, Pb, S, Si, and Sn. Files can be saved with individual structures or a database of structures. 

Table 5.11 H2O/D2O solvent isotope effects on gas solubility. Thermodynamics of transfer at 298.15 K, AY = Y (H2O) — Y (D20) (Scharlin, P. and Battino, R.. /. Solut. Chem. 21, 67 (1992). Fluid Phase Equlib. 94, 137 (1994))...

As described in the general introduction for solubility assays, there is a difference between kinetic and thermodynamic solubility. Thermodynamic solubility needs solid material of good quality whereas kinetic solubility relies on organic stock solutions. The sample preparation is therefore different (Kibbey). 

Solubility is a key property in the distribution of the compound from the gastrointestinal tract to the blood. There have been several modeling efforts to predict the solubility, based on different type of descriptors. The intrinsic solubility (thermodynamic solubility of the neutral species) for a set of 1028 compounds has been modeled using the VolSurf descriptors based on GRID-MIFs (Fig. 10.9(a)) and PLS multivariate analysis [20]. The interpretation of the model can be based on the PLS coefficients the ratio of the surface that has an attractive interaction with the water probe contributes positively to the solubility, while the hydrophobic interactions and log P have a negative contribution. 

Water solubility (thermodynamic) prediction, based on various literature datasets [32, 33], is comparable to other models [29]. This model was confirmed with GPSVS. 

These are prepared by rapid solidification of the fused melt of two components that show complete liquid miscibility but negligible solid-solid solubility. Thermodynamically, such a system is an intimately blended physical mixture of its two crystalline components. Thus, the X-ray diffraction pattern of a eutectic constitutes an additive composite of the two components. A phase diagram of a two-component system is shown in Fig. 1. Examples of this type include phenacetin-phenobarbital, chloramphenicol-urea, griseofulvin-sucdnic acid, paracetamol-urea, and the dispersions of giiseofulvin and tolbutamide in polyethylene glycol-(PEG-2000).[ ... 

In a wet atmosphere, iron and steel corrode producing first hydrated ferrous ions at the anodic site and hydrated hydroxide ions, OHaq, at the cathodic site where air-oxygen is reduced into OHaq ions. The presence of salts such as NaCl is known to enhance corrosion. Hydrated ferrous ions occur in the form of Fe2+, Fe(OH)+, Fe(OH) aq, and Fe(OH) aq. Gel-like hydroxide of Fe(OH)2,solid precipitates when the concentration of hydrated ferrous ions exceeds its solubility. Thermodynamic calculation gives the proton level to be pH 9.31 and 1.27 x 10 5 mol dm 3 of solubility at which the equilibrium is established between gel-like Fe(OH)2,soiid and hydrated OHaq ions when Fe(OH)2solid is put in pure water [90]. 

From the above qualitative discussion it can be clearly derived that at least four important factors, namely interphase mass transfer, solubility, thermodynamic phase equilibria, and intrinsic kinetics must be considered during quntitative analysis of gas-liquid-liquid reactions (Figure 3). 

The two extreme-case phase diagrams shown in Fig. 1.6-1 indicate that the phase behavior of a solid-liquid mixture depends crucially on die extent to which the solids are mutually soluble. Thermodynamic calculations are relatively straightforward when it is reasonable 10 assume that all possible solid phases are pure, because in that event we need noi he concerned with activity coefficients in I ha solid phase at present, little is known about these activity coefficients. 

The ternary system Si-B-C was optimized in the scope of our work on the Si-B-C-N system [33, 34]. The other three ternary systems (Si-B-N, Si-C-N, B-C-N) could be calculated comprehensively by thermodynamic extrapolations since all solid phases have negligible ranges of solubility. Thermodynamic data of the ternary phases pSiCJti4 and Si2CN4, are not known yet, however they are reported not to be stable at the conditions treated here (P = 1 bar, T > 1300 K) [21]. 

Mineral Composition Molecular mass, g-mole Equilibrium constant Solubility Thermodynamic properties at, 298,15 K, kj-mole ... 

Phi-phi. If a reliable PvTx equation of state is available, then we may use the phi-phi method to compute gas solubilities. Thermodynamically, this is merely phi-phi applied to VLB and the general approach has been discussed in 10.1.1 and 12.1.1. But in practice, this is a relatively recent development because reliable equations of states have only recently been devised for supercritical solutes in subcritical solvents. When the phi-phi method is used, computed solubilities are found to be sensitive to the temperature dependence of parameters in the equation of state they are also sensitive to the mixing rules used for those parameters. In particular, when cubic equations are used, the temperature dependence and mixing rule for the parameter a must be chosen with care. However, we judge this to be a modeling problem, not a thermodynamic problem. 

Irreversible thermodynamics molar volumes multicomponent systems non-aqueous osmotic coefficients oxidation-reduction potentials sodium chloride solubilities thermodynamics of mixing uni-polyvalent uni-univalent viscosity... 

Solubility, thermodynamic and kinetic acidities of nitroalkanes are of great importance in the course of the reaction, but the hydrophobic effect (Lubineau et al., 1994a) could be involved, since additives such as glucose or saccharose accelerate the reaction even more (Lubineau and Aug6, 1992). Amphiphilic molecules can also influence the hydrophobic interactions. In fact, cetyltrimethylammonium chloride (CTACl) as cationic surfactant promoted the Michael reaction of various nitroalkanes with conjugated enones in dilute aqueous solutions of sodium hydroxide (Ballini and Bosica, 1996) ... 

POM macroions allow a connection between simple ions and colloidal systems to be established. Similar to simple ions, POM macroions are highly soluble, thermodynamically stable, and form real solutions. However POMs macroanions are significantly larger than common simple ions, leading to a large size disparity between cations and anions. At the same time, the sizes of POM are close to some small colloids. Colloidal systems are insoluble, thermodynamically unstable, and form suspensions, but POMs do not display any of these characteristics. Instead, they form stable real solutions. 

In order for cooling crystallization to be an attractive method of separation, it is necessary that one component come out of a solution as the temperature changes. This can be determined by solubility thermodynamics. Understanding these relationships is fundamental to the equipment design. 

---