Total metal cation equation

By means of Equation 2.54, knowing the pH, the total concentration of the complex-forming agent, its pH-dependent a parameter, and the stability constants of its complexes, the ratio of the free cation and the total metal ion concentration... 

Flameless atomic absorption spectroscopy using the heated graphite furnace is a sensitive method for analyzing environ-mental samples for trace metals. High salt concentrations cause interference problems that are not totally correctable by optimizing furnace conditions and/or using background correctors. We determined that samples with identical ratios of major cations have trace metal absorbances directly related to their Na and trace metal concentrations. Equations and curves based on the Na concentration, similar to standard addition curves, can be calculated to overcome the trace element interference problem. Concentrations of Pb, Cd, Cu, and Fe in sea water can be simply (ind accurately determined from the Na concentration, the sample absorbance vs. a pure standard, and the appropriate curve. 

The substitution of the melt-anion in a molten alkali-metal halide, i.e. proceeding from chloride melts to bromides and iodides, results in the appreciable reduction in the contribution of the ionized constituent (Me2+ concentration) in the total oxide solubilities in the said melts. The data allow us to trace the effect of the constituent halide ion on the solubilities of metal-oxides in the corresponding melt. It should be noted that the substitution of chloride ions with bromide ones results in an appreciable reduction in the solubilities of all the metal-oxides studied, i.e. the values of pPMeo N become lower by 1-2 orders. At the same time, the oxide dissociation in the saturated solution of the oxide reduces. Thus, a considerable reduction in metal-oxide solubilities in bromide melts as compared with chloride ones can be explained in a similar way. Equilibrium (2.4.13) which takes place at the dissolution of a metal-oxide in an ionic halide melt is superimposed upon the interactions of the metal cation with the anions of the melt-solvent, which are denoted hereafter as X (equation (3.6.3)). 

Note the similarity between Uqualion 23-13 and liquations 23-2 and 23-4 for metallic cation indicator electrodes. It is important to emphasi/.c that although Lquations 23-2 and 23-4 are similar in form to [Equation 23-13, the sources of the potential of the electrodes that they describe are totally different — one is a redox potential, and the other is a boundary potential. 

Complexation of cations and anions is achieved by introducing mass action expressions for the formation of the cation or anion surface complex into the mass balance for the total number of surface complexation sites and, if the new surface species is charged, into the charge balance equation, e.g. metal surface complexes, Cd2+. 

For modeling the release of Sr, Ni, and Zn, two approaches were taken. In the first model, the total concentration of Sr, Ni, and Zn available for cation exchange reactions was fixed as the sum of the initial concentrations of soluble and exchangeable concentrations as in equation 9.6. In the second model, the concentrations of Zn, Ni, and Sr released by dissolution of Mn oxide were included and were considered to be available for cation exchange reactions. The corresponding equation for the total concentration of each metal for the second model was... 

Equation (69) divides the pressure into contributions from the volume dependence of the band centres (the first term) and the volume dependence of the bandwidth (the second term). The band contribution vanishes for empty and filled bands. Equation (69) may be transformed into a very instructive form by inserting estimates for Ef and p and evaluating the cation f and anion p contributions to the pressure. The total number of states, per formula unit, in the p and f bands are 6 and 14, respectively. The p band is pushed downwards by an amount by the f band and contains 6 - Nfp electrons with local anion p character and electrons with local cation f character. The f band is pushed upwards by an amount Sf and contains /(14 — Aipj) electrons with local cation f character and /Np[ electrons with local anion p character. The lower and upper parts of the projected densities of states (fig. 58) are the bond and anti-bond parts, respectively, and their centres of gravity may be estimated separately. This has been done by Andersen et al. (1979) for transition metal monoxides and by Brooks et al. (1984) for NaCl-type actinide compounds. When these estimates are inserted, eq. (69) reduces, when Nfp 14, to... 

---