Example calculations Davies equation

In this particular example, the Davies equation (15) gives the same value as Equation 1 it seems to be applicable, therefore, to calculating TKs values of oxides and carbonates of bivalent metals from Ks data in 0.2M NaC104. It fails, however, if applied to data which were evaluated in media of higher ionic strengths. 

Example 3.3 Calculation of the mixed acidity constant, K, using the Giintelberg approximation and the Davies equation. 

Simple thermodynamic calculations based on literature data (5-12) support the choice of phosphates as the optimum mineral phases for actinide immobilization. The calculations considered every relevant species reported (5-72) that contained protons, hydroxide, or the ligand in question for each metal ion. Where necessary, equilibrium constants were corrected to 0.1 M ionic strength using the Davies equation. As an example, the calculated solubility of europium, thorium, and uranium in various media at p[H] 7.0 (p[H] = - log of the hydrogen ion concentration), 0.001 M total ligand concentration, 0.1 M ionic strength, and 25 °C are shown in Table I. Within the constraints of the calculation, the solubility of thorium is limited by Th(OH)4, but the lowest europium and uranyl solubilities are observed for phosphates. 

A number of computer programs related to the liquid-junction photovoltaic cell have been developed. Leary et al.205 for example, calculated carrier concentrations in polycrystalline films using a numerical solution of Poisson s equation coupled with overall charge neutrality within spherical grains. Their model was used for analysis of semiconductor gas sensors. Davis and colleagues206"208 presented a computer program which uses simultaneous calculation of surface and solution equilibrium states to obtain the equilibrium condition of electrical double layers. 

Calculate the activity coefficient for the solution of Example 6.14 using the Davies equation. Find the percent difference between the resnlt of the Davies equation and that of the Debye-Hiickel limiting law. 

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