Solubility, diagram

In addition to speciation diagrams on a percent species basis (Section 2.1.4), solubility diagrams can be plotted on a logarithmic scale of molar concentration. For example, in the case of Al(OH)3s, a mineral which regulates aluminum in the solution of many soils, the solubility can be expressed as follows  

Xgq = 10 51. Using the equilibrium expression for the above reaction and solving for Al(OH)2+, the logarithmic equation is 

Aluminum-hydroxy species are known to exhibit different biological activity. For xample, data have shown that some leafy plants are sensitive to Al3+ while others are mown to be sensitive to Al(OH) monomers. It has also been shown that polymeric duminum (more than one A1 atom per molecule) is toxic to some organisms. Alumi-lum is one of the cations most difficult to predict in the soil solution. This is because t has the ability to form complex ions such as sulfate pairs and hydroxy-AI monomers ind polymers. 

The presence of sulfate in water can alter the solubilities of gibbsite and kaolinite, wo minerals considered to control the concentration of aluminum in natural waters, lius, minerals of lesser solubilities control the aluminum concentration in acid sulfate vaters. These minerals most likely are alunogen [Al2(SO4)317H20s], with a Ksp of 0 7 alunite [KA13(S04)2(0H)6s], with a Ksp of KT85 4 jurbanite [AKSO OH)- 

Crystallization ( Organic Compounds An Industrial Perspective. By H.-H. Tung, E. L. Paul, M. Midler, and J. A. McCauley 

Two factors complicate these simple representations. They are the effect of increasing distiUation temperature caused by the increasing concentration of substrate and impurities. The impurities, in particular, can dramatically increase the solubility of the substrate. They can also decrease the inherent growth rate by blocking or inhibiting surface incorporation on the growing crystals or by reducing the nucleation rate. These effects are represented as curve H-E in Fig. 8-2. As distillation proceeds, the solubility increases. In extreme cases, the crystals once formed could melt as the temperature increases. 

Increasing solubility because of increased concentration of impurities will result in a similar equilibrium change, although in some cases, the effect could be much greater. In extreme cases, when the residual solvent concentration is reduced to less than a critical value, the substrate could melt or solidify, depending on the melting point and the impurity effect. This condition is often used in laboratory preparations for convenience in changing solvents and is referred to as concentration to dryness. It is obviously not a scalable operation in a stirred vessel. Specialized tubular evaporators with close-clearance or scraped-surface rotors are available for these applications and have been successfully used by the authors for concentration but not for simultaneous crystallization. 

The actual concentration curves that could result are shown in curve B-E. Obviously, a yield loss will result because of the increased equilibrium solubility. 

A less common effect of impurities is a decrease in the solubility of the substrate. This effect could be attributed to an impurity that is in high concentration because it will not crystallize under the existing conditions or because the temperature is above its melting point. The solvent capacity for the substrate is thereby decreased, resulting in decreased solubility. In aqueous systems, this effect could be caused by high inorganic salt concentrations and may be referred to as salting out. 

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McKetta "Survey of Solubility Diagrams for Ternary and Quarternary Liquid Systems," Bureau of Engineering Research, Special Publ. Nr. 30, University of Texas, Austin, 1959. 

Derive a solubility diagram (solubility versus pH) for Zn(OH)2 that takes into account the following soluble zinc hydroxide complexes Zn(OH)+, Zn(OH)3, Zn(OH)4 . 

SODIUMCOMPOUNDS - SODIUMHALIDES - SODIUM CHLORIDE] (Vol22) -solubility diagram for [CRYSTALLIZATION] (Vol 7)... 

Solubility, aqueous Solubility coefficient Solubility coefficients Solubility diagrams Solubility parameter Solubility parameters Solubility products... 

There are numerous solubility data in the literature the standard reference is by Seidell (loc. cit.). Valuable as they are, they nevertheless must be used with caution because the solubihty of compounds is often influenced by pH and/or the presence of other soluble impurities which usually tend to depress the solubihty of the major constituents. While exact values for any system are frequently best determined by actual composition measurements, the difficulty of reproducing these solubility diagrams should not be underestimated. To obtain data which are readily reproducible, elaborate pains must be taken to be sure the system sampled is at equihbrium, and often this means holding a sample at constant temperature for a period of from 1 to 100 h. While the published cui ves may not be exac t for actual solutions of interest, they generally will be indicative of the shape of the solubility cui ve and will show the presence of hydrates or double salts. 

Example 2 Yield from Evaporative Cooling Starting with 1000 lb of water in a solution at H on the solubility diagram in Fig. 18-57, calculate the yield on evaporative cooling and concentrate the solution back to point H so the cycle can be repeated, indicating the amount of NaCl precipitated and the evaporation and dilution required at the different steps in the process. 

Solubility of resins can be predicted in a similar way as for the solubility of polychloroprene rubbers in a solvent mixture (see Section 5.5) by means of solubility diagrams (plots of the hydrogen bonding index (y) against the solubility parameter (5). Another more simple way to determine the solubility of resins is the determination of the cloud point, the aniline and the mixed aniline points. 

Sodium reduction development directions, 336 diluted melts, 331-332 of K-Salt, 327-328 principals, 326 Solid-phase interaction mechanism, 34-37 niobium oxyfluorides, 26-31 tantalum oxyfluorides, 32-34 Solubility diagrams (NH4)5Nb3OF18, 22 K2NbF7 in HF solutions, 14 K2TaF7 in HF solutions, 14 RbsNbjOF,, 22-23 Solubility of peroxides, 307 Specific conductivity, 153, 164 Spontaneous polarization, 223 Structural characteristics for X Me=8, 61,... 

As the temperature of the system is raised, phases begin to disappear from the solubility diagram until at 175°C, only Ce02 ... 

The redox behavior of the SeSO -Zn-EDTA system has been discussed on the basis of Pourbaix and solubility diagrams [11], Different complexes and substrates have been employed in order to optimize the electrodeposited thin films. By the selenosulfate method it is generally possible to grow ZnSe with an almost stoichiometric composition however, issues of low faradaic efficiency as well as crystallinity and compactiveness of the product, remain to be solved. Interestingly, in most reports of photoelectrochemically characterized ZnSe electrodeposits, the semiconductor film was found to be p-type under all preparation conditions (ZnSe is normally n-type unless deliberately doped p-type). 

When the saturation limit is exceeded and excess pure solid remains undissolved and in contact with the solvent, the number of phases present now equals two. However, there are still only two components in the system, leading to the deduction that the number of degrees of freedom is zero. In practical terms, this means that there can be no variation in concentration as more solute is added to the system, and segment B-C of Fig. 5 is obtained. When solubility diagrams are obtained that exactly match the type shown in Fig. 5, it can safely be assumed that the solute under analysis is at least 99.9% pure. 

Fig. 9 Phase solubility diagram showing the changes in the apparent aqueous solubility of p-aminobenzoic acid (PABA) brought about by the addition of the complexing agent, caffeine, at 30°C. (The data are adapted from Ref. 51.)...

Fig. 21 Three-dimensional representation of a ternary system of two enantiomers in a solvent, S. One of the faces of the prism (at left) corresponds to the binary diagram of D and L (here a conglomerate). Shaded area isothermal section representing the solubility diagram at temperature T0. (Reproduced with permission of the copyright owner, John Wiley and Sons, Inc., New York, from Ref. 141, p. 169.)...

Fig. 22 Construction of a triangular solubility diagram. (Reproduced with permission of the copyright owner, John Wiley and Sons, Inc., New York, from Ref. 141, p. 176.)...

Fig. 12.1. Solubility diagram for aluminum species in aqueous solution as a function of pH at 200 °C in the presence of boehmite (solid lines) and kaolinite plus quartz (dashed lines). Aluminum is soluble at a specific activity (horizontal line) either under acidic conditions as species Al(OH), A10H++, or A1+++ (e.g., point A), or under alkaline conditions as Al(OH)4 (point B).

Muller, B., 2004, ChemEQL V3.0, A program to calculate chemical speciation equilibria, titrations, dissolution, precipitation, adsorption, kinetics, pX-pY diagrams, solubility diagrams. Limnological Research Center EAWAG/ETH, Kastanienbaum, Switzerland. 

Solubility Diagrams effects of atomic properties on mutual solubility. The effect on mutual solubility of the atomic properties of the components (and therefore of their relative positions on the map shown in Fig. 2.8) may be considered on the basis also of different diagrams. 

Figure 4. Solubility diagram for PSF, SPSF-Na (0.16), SPSF-Na (0.34), SPSF-Na (0.53), and SPSF-Na (0.68)...

Figure 14.2 Solubility diagram. During equilibration, the concentration of both precipitant and macromolecule increase until precipitation occurs. The formation of crystal nuclei reduces the amount of solvated macromolecule and allows the system to remain in the metastable zone where crystals can grow.

The sum of all the soluble Fe " species, i. e. Fer, in equilibrium with goethite as a function of pH, is the heavy line in the solubility diagram in Figure 9.1, whereas the activities of the single species are shown by the weak lines. Inclusion of the hydrolysis species results in a much higher solubility than would be observed by consideration of the solubility product i. e. Fe ", alone. For example, at pH 6, is <10 M, whereas Upe. = 10 M. Only at very low and very high pH is Up. essentially equal to UpeJt and ape(OH)j. respectively. 

Solubility diagrams have nearly always been calculated using solubility and stability constants. Experimental determination of the solubility of iron oxides as a function of pH has been concerned predominately with ferrihydrite. Lengweiler et al. 

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