Aluminium solubility constant

Table 5.4 Solubility constants ( Kso) of some aluminium-containing minerals...

The solubility constants of some aluminium-containing minerals are shown in Table 5.4. 

The overriding aim of our research on HAS(j) is to elucidate their role in the biogeochemical cycle of aluminium [16] and specifically to understand how they keep aluminium out of biota [17]. This has led us to try to define a solubility expression for HASb(s) order that such might be used quantitatively in predictive models of aluminium solubility control in soil and surface waters [18]. The solubility constant which we derived from our unconventional solubility expression ... 

K.J. (1993) Aluminium hydrolysis constants to 250 °C from boehmite solubility measurements. Geochim. Cosmochim. Acta, 57, 747-762. 

Boehmite (y-AlOOH(s)) becomes the stable solid oxyhydroxide phase of aluminium at a temperature of around 100 C. However, solubiUty data at zero ionic strength are available to lower temperatures (on the basis of the reported temperature dependence of the solubility). The relationship between the solubility constants and temperature is illustrated in Figure 13.2. As was the case with gibbsite. 

The -modification is the main constituent of the majority of the Si3N4 ceramics. Different space groups were observed the centrosymmetric P63/m [45] and the corresponding non-centrosymmetric P63 [25, 35], Detailed investigations on single crystals reveal P63. The atomic coordinates in the unit cell remain nearly constant up to 1633 K [48], Deviations from the observed cell dimensions are presumably caused by aluminium and oxygen impurities (Sect. 3). The solubility of oxygen in the / structure is up to 0.258 wt% in the absence of other elements [49]. 

Nitric acid is a colourless liquid at room temperature and atmospheric pressure. It is soluble in water in all proportions and there is a release of heat of solution upon dilution. This solubility has tended to shape the process methods for commercial nitric acid manufacture. It is a strong acid that almost completely ionizes when in dilute solution. It is also a powerful oxidizing agent with the ability to passivate some metals such as iron and aluminium. A compilation of many of the physical and chemical properties of nitric acid is presented in Table A.1 of Appendix A. Arguably the most important physical property of nitric acid is its azeotropic point, this influences the techniques associated with strong acid production. The constant-boiling mixture occurs at 121.9°C, for a concentration of 68.4%(wt) acid at atmospheric pressure. 

Iron-nickel alloys are known to dissolve in the aluminium melts non-selectively. " As seen from Table 5.3, during dissolution of a 50 mass % Fe-50 mass % Ni alloy the ratio, cFe cNi, of iron to nickel concentrations in the melt is 1.00 0.05, i.e. it is equal to that in the initial solid material. The same applies to other alloys over the whole range of compositions. Respective saturation concentrations are presented in Table 5.4. The data obtained display a strong mutual influence of the elements on their solubilities in liquid aluminium because in its absence the solubility diagram for a constant temperature would be like that shown by the dotted lines in Fig. 5.5, with the eutonic point, E, at 2.5 mass % Fe and 10.0 mass % Ni. The effect of iron on the nickel solubility is seen to be more pronounced than that of nickel on the iron solubility. 

In contrast to the solubility, the values of the dissolution-rate constants of different metals and alloys in liquid aluminium are very close. At least, they are of the same order of magnitude, namely 10 5 m s1, although the solubility values may differ by two orders of magnitude or more (see Table 5.2). This is also typical of dissolution of other solid substances in liquids.299 301... 

There is little information on rates of initiation in coordination polymerization. With the soluble catalyst (7r-CsHs)2TiCl2—AlMejCl for ethylene, Chien [111] reported = 4.99 x 10 1 mole s at 15°C Ei = 15.5 kcal mole ). This was determined from the rate of incorporation of C14 labelled AlMe2 Cl into the polymer. In most systems examined the initiating centres have been preformed and reaction starts immediately. This is the case with Natta type catalysts from transition metal subhalides with the alkyls of aluminium, beryllium and zinc. With some catalysts the rate rises rapidly to a steady value but with others there is a rapid rise to a maximum followed by a decline to a constant rate, the latter being... 

In humid, tropical climates, weathering is rapid, partly because the high temperatures speed up reactions, but mainly because the consistent supply of heavy rainfall allows rapid flushing and removal of all but the most insoluble compounds, for example oxides of aluminium and iron (Section 4.7). Flushing constantly removes (leaches) soluble components and is particularly important in the undersaturated zone of soils (Box 4.9). 

Thus in contact with aluminium and ferric phosphates, the aluminium and ferric ion concentrations are reduced and so the phosphate ion concentration is increased to maintain the solubility product at their constant levels. AIPO4 represents various hydrated and hydroxyl phosphates of aluminium, including any adsorbed or precipitated surface layers on oxides and alumino-silicates. FePO similarly, represents various hydrated and hydroxyl phosphates of iron including adsorbed or precipitated surface layers on iron oxide. 

The stability of natural oxide film, which governs the corrosion resistance of aluminium, depends on pH (Figure B.1.18). Most natural, untreated and unpolluted surface waters have a pH between 6.5 and 7.5. Since the solubility of alumina is minute and is practically constant in this pH range (Figure D.1.14), pH is not an important factor for the corrosivity of natural waters. 

There is a paucity of available data for the solubility of indium oxide and hydroxide phases. As the first hydrolysis constant of indium has a stability that lies between those of aluminium and gallium, it is expected that the solid hydroxide phase would also exhibit this behaviour. However, a number of studies (Heyrovsky, 1925 Oka, 1938 Moeller, 1941 Lacroix, 1949) have indicated a solubility that was larger than that seen for aluminium(III). It is believed that this would be unlikely and, as such, these data are not retained. AkseTrud and Spivakovskii (1959) obtained a solubility that was nearly four orders of magnitude smaller than... 

Korenman, I.M., Frum, F.S., and Kudinova, A.I. (1953) Determination of the solubility product constant of aluminium hydroxide. Sbornik Slat. Ohshch. Khim., 1, 83-85. 

Singh, S.S. and Brydon, J.E. (1969) Solubility of basic aluminium sulfates at equilibrium in solution and in the presence of montmorillonite. Soil ScL, 107, 12—16. Sipos, P., Capewell, S.G., May, P.M., Hefter, G.T, Laurenczy, G., Lukacs, F., and Roulet, R. (1997) tI-NMR and UV-Vis spectroscopic determination of the formation constants of aqueous thallium(l) hydroxo-complexes. J. Solution Chem., 26, 419-431. Srinivasan, K. and Rechnitz, G.A. (1968) Reaction rate measurements with fluoride ion-selective membrane electrode. Formation kinetics of ferrous fluoride and aluminium fluoride complexes. Anal. Chem., 40, 1818-1825. 

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