Solubility apparent” mineral

The limitations of the solubility method for surface measurement are readily apparent. Mineral particles are usually conglomerate, or composed of crystals often loosely bound. A strong acid such as hydrofluoric acid tends to split up the particles or penetrate so far that the true surface is exaggerated. Another difficulty concerns the assumption that all portions of a given particle-surface dissolve uniformly this is not the case. The solubility of indentations or discontinuities is not uniform, especially since such points have occluded gases which are not affected. In most instances these factors are probably averaged out, and excellent approximations of the true surface may be made but instances will undoubtedly arise where they are of great importance. 

Estimation of long-term dissolution rate constants (Kl t) from 2-6 week surface flux averages and "apparent" mineral solubilities. 

Lesions created in both bovine and human enamel, in an acidified methyl cellulose gel system, displayed many of the same qualitative trends [Lynch, unpubl. data]. After an initial period of approximately 3 days when dissolution was negligible, mineral loss was typically found at a series of discrete locations, with no apparent mineral loss between these pockets of demineralisation. Surface zones were typically poorly defined or absent. After 5 or more days, the isolated pockets had coalesced and lesions were uniform in terms of both depth and mineral loss across the bulk of the lesion body, with well-defined surface zones. When observed under polarised light, these initial pockets of demineralisation were very often coincident with Hunter-Schreger banding. This was particularly noticeable in bovine enamel. Shellis [64] reported variations in solubility related to enamel microstructure and suggested that structure/solubility relationships are likely to influence lesion formation. 

Metal complexation in solution can have the effect of increasing the apparent solubility of minerals. A case in point is the oxalic acid—A1 hydroxide system. Oxalic acid, naturally occurring in soils as a product of biological activity, is a relatively strong dicarboxylic acid that dissociates readily ... 

Under normal laboratory conditions, the great bulk of this ore is soluble in mineral acids. No selectivity is apparent in the rates of solution of the various components up to the normal boiling point. ... 

It appears to be the case that most animals maintain the concentration of mineral ions at constant levels in their extracellular fluids. Perturbations with various forms of acidosis usually result in the animal re-establishing an equilibrium between its body fluids and the apparent solubility product of some mineral. Two important conclusions follow from this. First, it provides a theoretical basis for defining calcification. When there is a change of phase in the total extracellular fluids (i. e., mineralization occurs) then the fluids re-equilibrate to make good the ions which have been lost as minerals. 

Since NaOH and NaA102 had no apparent effect on cobalt solubility, it seemed likely that cobalt sorption was increased by these components due to effects they had on the sediment minerals. Studies of the effects of NaOH and NaA102 on the sediment minerals are required to identify possible new mineral phases which might cause increased cobalt sorption. 

A cold early climate and a thin CO2 atmosphere are consistent with the ubiquity of primary igneous minerals and the apparent absence of secondary minerals and copious carbonates on the surface. Aqueous eruptions introduced soluble chloride and sulfate salts into Martian soils, leaving clays and carbonates within the crust. If the Martian crust hosts a deep biosphere, aqueous eruptions could bring organisms or their chemical signature to the surface. The biotic component of any recent eruptions may be preserved in transient ice in cold traps on the surface. 

Most studies of carbonate chemistry in deep sea sediment pore waters have, therefore, focused on the the apparent solubility behavior of carbonates in these sediments. The basic hypothesis is that because of the relatively fast reaction kinetics of carbonate minerals and generally low sedimentation rates in deep sea... 

The importance of single-ion activity in predicting the chemical behavior of a particular ionic species is demonstrated in Figure 2.1. For example, the y value of any divalent or monovalent ions at the highest possible ionic strength (7) causes 60% suppression in the activity of the divalent ion and 25% reduction in the activity of the monovalent ion. This implies that as Yj decreases, the apparent solubility of any given mineral increases, as demonstrated later in this chapter. 

Interfacial Metal Ion Complexatlon. Complexatlon of copper (II) ion by oil soluble ligands has been implicated in metallo-porphyrin formation in benzene in water MB s, but not apparently in the mineral oil in water system (vide supra). Therefore, an electrochemical study of the interaction of quinoline and copper ion was undertaken. 

It might also be argued for a number of minerals that the paucity of data precludes any estimate of "apparent" solubilities. This argument is valid to the extent of the degree of accuracy required by the critic. We undertook to survey a large number of common minerals in a general way within a finite set of time constraints. We have no doubt that future workers will improve upon our data, but we also feel that reasonable estimates along with their uncertainties are better than no data at all. 

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