Aluminium solubility 97, Table

The aluminium ion, charge -I- 3. ionic radius 0.045 nm, found in aluminium trifluoride, undergoes a similar reaction when a soluble aluminium salt is placed in water at room temperature. Initially the aluminium ion is surrounded by six water molecules and the complex ion has the predicted octahedral symmetry (see Table 2.5 ) ... 

The data given in Tables 1.9 and 1.10 have been based on the assumption that metal cations are the sole species formed, but at higher pH values oxides, hydrated oxides or hydroxides may be formed, and the relevant half reactions will be of the form shown in equations 2(a) and 2(b) (Table 1.7). In these circumstances the a + will be governed by the solubility product of the solid compound and the pH of the solution. At higher pH values the solid compound may become unstable with respect to metal anions (equations 3(a) and 3(b), Table 1.7), and metals like aluminium, zinc, tin and lead, which form amphoteric oxides, corrode in alkaline solutions. It is evident, therefore, that the equilibrium between a metal and an aqueous solution is far more complex than that illustrated in Tables 1.9 and 1.10. Nevertheless, as will be discussed subsequently, a similar thermodynamic approach is possible. 

Various extraction methods for phenolic compounds in plant material have been published (Ayres and Loike, 1990 Arts and Hollman, 1998 Andreasen et ah, 2000 Fernandez et al., 2000). In this case phenolic compounds were an important part of the plant material and all the published methods were optimised to remove those analytes from the matrix. Our interest was to find the solvents to modily the taste, but not to extract the phenolic compounds of interest. In each test the technical treatment of the sample was similar. Extraction was carried out at room temperature (approximately 23 °C) for 30 minutes in a horizontal shaker with 200 rpm. Samples were weighed into extraction vials and solvent was added. The vials were closed with caps to minimise the evaporation of the extraction solvent. After 30 minutes the samples were filtered to separate the solvent from the solid. Filter papers were placed on aluminium foil and, after the solvent evaporahon, were removed. Extracted samples were dried at 100°C for 30 minutes to evaporate all the solvent traces. The solvents tested were chloroform, ethanol, diethylether, butanol, ethylacetate, heptane, n-hexane and cyclohexane and they were tested with different solvent/solid ratios. Methanol (MeOH) and acetonitrile (ACN) were not considered because of the high solubility of catechins and lignans to MeOH and ACN. The extracted phloem samples were tasted in the same way as the heated ones. Detailed results from each extraction experiment are presented in Table 14.2. 

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. 

All other sulphates are soluble in water, and can therefore be prepared by one of the usual methods, such as treatment of the oxide, carbonate, or metal with the acid. Dilute sulphuric acid dissolves magnesium, zinc, cadmium, aluminium, chromium, iron, manganese, nickel, and cobalt other metals resist its attack, because their electroaffinity is less than that of hydrogen. The order is Cs, Rb, K, Na, Li, Ba, Sr, Ca, Mg, Al, Mn, Zn, Cd, Cr, F e, Co, Ni, Pb —H Cu, Hg, Ag, Pt c., Au. All the metals to the left of hydrogen in the table are attacked, because they receive their ionic charge from the hydrogen... 

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. 

Table 5.2. Solubilities (mass %) of transition metals in liquid aluminium...

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. 

Dissolution of iron-chromium alloys in molten aluminium bears a similar character, at least at chromium contents up to 25 mass %. The ratio, cFe cCr, of iron to chromium concentrations in the melts corresponds to that in the initial alloys (Table 5.5). At 700°C, the solubilities (saturation concentrations) are 2.5 0.2 mass % Fe and 0.28 0.03 mass % Cr for a 90 mass % Fe-10 mass % Cr alloy and 2.2 0.2 mass % Fe and 0.72 0.06 mass % Cr for a 75 mass % Fe-25 mass % Cr alloy. 

Table 5.4. Values of solubilities (saturation concentrations) of iron and nickel from Fe-Ni alloys in liquid aluminium at 700°C 310...

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... 

Binary or ternary catalyst systems from nickel compounds with Group I—III metal—alkyls have many features in common with those from cobalt and it may be inferred that a similar type of catalytic entity is involved. The composition for optimum activity may be different, however, and in the soluble catalyst Ni(naphthenate)2/BF3. EtjO/AlEtj (Ni/B/Al = 1/7.3/6.5) [68] the ratio of transition metal to aluminium is much higher than in cobalt systems. Rates were proportional to [M] and [Ni], molecular weight was limited by transfer with monomer and catalyst efficiency was relatively low (Table 5, p. 178). With the system AlEtj/ Ni(Oct)2/BF3—Et2 0 (17/1/15) the molecular weight rose with increase in [M] /[Ni] ratio and 3—9 chains were produced per nickel atom. It was observed that as molecular weight increased so the cis content of the polymer increased — from ca. 50% up to ca. 90% [292]. 

Aluminium is largely insoluble during weathering processes (Table 5.1), but becomes soluble when pH is both low and high. At the simplest level, three aluminium species are identified soluble Al , dominant under acid conditions, insoluble aluminium hydroxide (Al(OH)3), dominant under neutral conditions, and Al(OH)i, dominant under alkaline conditions. 

According to the ternary phase diagrams of aluminium-chromium-nickel [7] chromium is soluble in p-NiAl up to about 4 at.% at 1000°C. This is in agreement with the EPMA results for these alloys.The 0 at 1 at.% Cr alloys were homogeneous whereas, segregation was observed in the 5 and 10 at.% Cr alloys. In Table 2 the composition of the alloys, determined with XRF, is reported. In the EPMA-micrographs in Fig. 3 chromium enrichment (a-Cr) can be seen at the grain boundaries. 

Schreiner et al. developed thiourea catalyst as a promising hydrogen donor, which has more benefit in solubility, synthesis and catalytic mrn over number compared with urea catalyst, in the Diels-Alder reaction of A-crotonyloxazolidinone and cyclopentadiene [22,23] (Table 9.7). A,A -Di[3,5-bis(trifluoromethyl)phenyl]thiourea accelerates the reaction and improves stereoselectivity (run 4) similar to a metal catalyst such as aluminium chloride (AICI3) (mn 2) or titanium chloride (TiCls) (run 3). 

The solubility of alkaline earth metals in molten alkali metals is limited. The elements of the third group of the periodic table of elements are still less soluble in alkali metals, only the aluminium-lithium system is an exception. This system contains two intermetallic phases, LiAl and the peritectic phase Li9Al4, and solid alloys of both metals are of technical importance. The metals of the fourth group have a better solubility in alkali metals. They tend to form intermetallics. Some of the liquid alloys have found technical interest. 

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