Equilibrium, chemical INDEX

EQUIL A.E. Lutz and F. Rupley, Sandia National Laboratories, Livermore, CA. A Fortran computer program (eqlib.f) for calculating chemical equilibrium using a modified solution procedure of STANJAN (stanlib.f, W.C. Reynolds, Stanford U.) and CHEMK1N data files for input. For the most recent versions, refer to the Reaction Design website http //www.reactiondesign.com/lobby/ open/index.html. 

Octanol/Water Partition Coefficient (Kow) — the equilibrium ratio of the concentrations of material partitioned between octanol and water. This coefficient is considered to be an index of the potential of a chemical to be bioaccumulated. Higher values of K, are associated with greater bioaccumulative potential. 

Chemical reactivity and NMR spectroscopy suggested that the tria-zolopyrimidines with bridgehead nitrogens are planar and possess a high degree of aromatic character (80PAC1611). The aromaticity of 6-nitrotriazolopyrimidines was found to be more sensitive to substituent effects than the ANs index (91ZOR144). The tautomeric equilibrium of the... 

Tables of azeotropes and nonazeotropes compiled by L. H. Horsley and coworkers at the Dow Chemical Co. Included are a formula index, a bibliography, and three articles, "Vapor-Liquid Equilibrium Diagrams of Alcohol-Ketone Azeotropes as a Function of Pressure, ...

Experimentally, the investigation of adsorption from solution is much simpler than that of gas adsorption. A known mass of adsorbent solid is shaken with a known volume of solution at a given temperature until there is no further change in the concentration of the supernatant solution. This concentration can be determined by a variety of methods involving chemical or radiochemical analysis, colorimetry, refractive index, etc. The experimental data are usually expressed in terms of an apparent adsorption isotherm in which the amount of solute adsorbed at a given temperature per unit mass of adsorbent - as calculated from the decrease (or increase) of solution concentration - is plotted against the equilibrium concentration. 

Refs. [i] Denbigh KG (1987) Principles of chemical equilibrium, 4til edn. Cambridge University Press, Cambridge [ii] McNaught AD, Wilkinson A (1997) IUPAC Compendium of chemical terminology, 2nd edn. Blackwell Scientific Publications, Oxford [iii] http //www.iupac.org/ publications/compendium/index.html... 

After writing mass balances, energy balances, and equilibrium relations, we need system property data to complete the formulation of the problem. Here, we divide the system property data into thermodynamic, transport, transfer, reaction properties, and economic data. Examples of thermodynamic properties are heat capacity, vapor pressure, and latent heat of vaporization. Transport properties include viscosity, thermal conductivity, and difiusivity. Corresponding to transport properties are the transfer coefficients, which are friction factor and heat and mass transfer coefficients. Chemical reaction properties are the reaction rate constant and activation energy. Finally, economic data are equipment costs, utility costs, inflation index, and other data, which were discussed in Chapter 2. 

A suite of both oxidized and reduced iron minerals has been found as efflorescences and precipitates in or near the acid mine water of Iron Mountain. The dominant minerals tend to be melan-terite (or one of its dehydration products), copiapite, jarosite and iron hydroxide. These minerals and their chemical formulae are listed in Table III from the most ferrous-rich at the top to the most ferric-rich at the bottom. These minerals were collected in air-tight containers and identified by X-ray diffractometry. It was also possible to check the mineral saturation indices (log Q(AP/K), where AP = activity product and K = solubility product constant)of the mine waters with the field occurrences of the same minerals. By continual checking of the saturation index (S.I.) with actual mineralogic occurrences, inaccuracies in chemical models such as WATEQ2 can be discovered, evaluated and corrected (19), provided that these occurrences can be assumed to be an approach towards equilibrium. 

The second scheme, which is more generally used, involves a hybrid procedure patterned after the methodology of Section 2.11. Here one distinguishes between pure condensed phases, indexed by the symbol s, and components forming homogeneous mixtures, indexed by the symbol j. For the pure condensed phases one adopts Eq. (3.6.2) in the specification of the chemical potential for species in solution it is conventional to introduce Eq. (3.5.21). The equilibrium condition for the reaction = 0 is now specified by... 

The solvent polarity, which is defined as the overall solvation capability of a liquid derived from all possible, non-specific and specific intermolecular interactions between solute and solvent molecules [4], cannot be represented by a single value encompassing all aspects, but constants such as the refractive index, the dielectric constant, the Hildebrand solubility parameter, the permanent dipole moment, the partition coefficient logP [5] or the normalised polarity parameter TN [6] are generally employed to describe the polarity of a medium. The effect of a solvent on the equilibrium position of chemical reactions, e.g. the keto-enol tautomerism, may also be used. However, these constants reflect only on some aspects of many possible interactions of the solvent, and the assignment to specific interactions is difficult if not impossible. 

Understand the relationships among Gibbs free energy, chemical potential, reaction quotients (Q), the equilibrium constant, and the saturation index SI). 

Here T is the temperature, p is the pressure, a is the surface tension, A is the surface area, V is the volume, 5 is the entropy density, Pi are the particle densities, and pi the chemical potentials of the different components, R is the radius of the critical cluster referred to the surface of tension, the index a specfies the parameters of the cluster while p refers to the ambient phase. The equilibirum conditions coincide with Gibbs expressions for phase coexistence at planar interfaces (R oo) or when, as required in Gibbs classical approach, the surface tension is considered as a function of only one of the sets of intensive variables of the coexisting phases, either of those of the ambient or of those of the cluster phase. In such limiting cases, Gibbs equilibrium conditions... 

The solvent in this case is a salt solution (solvent with small ions) which is in Donnan equilibrium with the polyelectrolyte solution, the index /xs means that the chemical potentials of all the solutes except that used in differentiation are constant, and K is given as [39]... 

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