Semi-solution formats

Measurements of photoconductivity and of the Hall potential [367] are accurate and unambiguous methods of detecting electronic conduction in ionic solids. Kabanov [351] emphasizes, however, that the absence of such effects is not conclusive proof to the contrary. From measurements of thermal potential [368], it is possible to detect solid-solution formation, to distinguish between electronic and positive hole conductivity in semi-conductors and between interstitial and vacancy conductivity in ionic conductors. 

The X-ray diffraction patterns of hydrothermally synthesised anhydrous nickel carbonate were taken, indexed and the constants of the unit cell ascertained. The T, p phase diagram of NiC03(cr) was determined semi-quantitatively. Solid solution formation between NiCOs and MgCOs was established. In addition hellyerite, NiC03-5.5H20, and zaratite were investigated. The latter turned out not to be a single mineral, but a composite of amorphous and fibrous components. 

This is very similar experimental work to that of [88BJE]. In this paper the formation of bromo complexes of nickel(II) was studied in 3.5 — 11.1 M LiBr solution. The semi-thermodynamic formation constant of NiBr was determined, and that of the complex NiBr2(aq) was estimated (see Table V-13). 

For precise work a calorimetric value of AH/ is usually essential, and this should also be known as a function of temperature, i.e., Cp l) — Cp s) must be included. Use of a AH/ value derived from other cryoscopic studies or from less accurate phase studies is at best suitable for only semi-quantitative work as this frequently will be seriously in error (often low). If so, any significant deviations from ideality in the original system, such as those due to specific associations, solid solution formation, or simply the result of measurements made inaccurately or at too high a solute concentration, would be carried over, and these factors would be expected to vary from one system to another. 

When submitted to oxidation by a 2 per cent, solution of permanganate, pinononic acid, CgHj Og, melting at 128° to 129° C., the semi-carbazone of which melts at 204° C. Lastly the constitution of verbenone, as expressed by the above formula, is further confirmed by the fact that the bicyclic system is convertible into a monocyclic system by boiling with 25 per cent, sulphuric acid, with the formation of acetone and 3-methylcyclohexene-(2)-one-(l). This cyclohexenone has been characterised by its semi-carbazone (melting-point 198° C.) and by its conversion into y-acetobutyric acid (melting-point 36° C). The oily liquid, which did not react with sulphite, was submitted to benzoylation after dilution with pyridine. It thus gave rise to a benzoate from which was... 

The distribution of metals between dissolved and particulate phases in aquatic systems is governed by a competition between precipitation and adsorption (and transport as particles) versus dissolution and formation of soluble complexes (and transport in the solution phase). A great deal is known about the thermodynamics of these reactions, and in many cases it is possible to explain or predict semi-quantita-tively the equilibrium speciation of a metal in an environmental system. Predictions of complete speciation of the metal are often limited by inadequate information on chemical composition, equilibrium constants, and reaction rates. 

A general presentation and discussion of the origin of structure of crystalline solids and of the structural stability of compounds and solid solutions was given by Villars (1995) and Pettifor (1995). For an introduction to the electronic structure of extended systems, see Hoffmann (1987, 1988). In this chapter a brief sampling of some useful semi-empirical correlations and, respectively, of methods of classifying (predicting) phase and structure formation will be summarized. 

Results for Commercial Operations The content of a-form was up to 99% and average size of the crystal was about 24-35 jum. The formation of 3-form crystal In commercial operation Induced considerable Increase of the viscosity of the suspension. The features of the semi-batch cooling crystallization process are as follows. Even if crystallization temperature is considerably lowered in order to avoid the formation of 3-form crystal, and also even if the feed solution is highly concentrated at high temperature above -SSSK, obtained crystal size is large enough to separate the solvent by centrifuge. 

In ultrafiltration and reverse osmosis, in which solutions are concentrated by allowing the solvent to permeate a semi-permeable membrane, the permeate flux (i.e. the flow of permeate or solvent per unit time, per unit membrane area) declines continuously during operation, although not at a constant rate. Probably the most important contribution to flux decline is the formation of a concentration polarisation layer. As solvent passes through the membrane, the solute molecules which are unable to pass through become concentrated next to the membrane surface. Consequently, the efficiency of separafion decreases as fhis layer of concentrated solution accumulates. The layer is established within the first few seconds of operation and is an inevitable consequence of the separation of solvent and solute. 

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