Logarithmic solubility diagrams

In the presence of a solid phase the distribution logarithmic diagrams are called solubility log concentration diagrams. From these diagrams it is possible to find the liquid phase composition (distribution of complexes and free-ion form) of the areas with predominating existence of the particular forms, total and minimum solubility of the solid phase and pH, or precipitant concentration required for separation of the solid phase at a given pH 

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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 ... 

Fig. 5.4-1 The logarithmic concentration diagram for HgS. The colored line shows the solubility S of mercury and sulfur.

Fig. 5.5-1 The logarithmic concentration diagram for the chloro complexes of Ag(I) in an aqueous solution equilibrated with solid AgCl. The colored line shows the silver solubility SAg. Note that, in this case, the solubility of the insoluble neutral species, AgCl, is quite substantial between a pCl of 2 and 3 it is the dominant component of the silver solubility SAg.

A) Logarithmic diagram of Al(III) solubility as function of Al concentration and pH, derived from ther-modyn. equilibrium constants. (B) Extent of Al-hydrol-ysis as function of pH. (C) Variation of the coagulation rate, expressed as collision efficieny factor, with pH at constant Al dosage (a values determined from Equation 3)... 

This method is based on the reactions between a reagent and relevant mineral species and using solubility product values. In pC-pH diagrams, the abscissa is pH of the solution the ordinate is negative logarithm of the precipitation concentration of the metallic ions. 

Master variables other than pH and pOH can be used in log concentration diagrams. Diagrams using the negative logarithm of concentrations of other ions are often useful in the solution of solubility problems. As an example consider the carbonate salts of and... 

The solubility increases once the concentration [H+] value approaches the Ka value. The phenomenon may be represented in a logarithmic diagram. Relation (34.12) may also be written as... 

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