CONSIDERATION OF THE PARTIAL CHARGE-TRANSFER IN THE GRAHAME-PARSONS MODEL AND THE CAPACITANCE DISPERSION UNDER SPECIFIC IONIC ADSORPTION FROM A MIXED 2-ELECTROLYTE SOLUTION

Calculation formulas were derived and a program composed for the Graha me-Parsons model, supplemented by the condition of partial charge tran sfer according to W.Lorenz and G.Salie. Impedance spectra of a polariz able electrode in a mixed two-electrolyte solution of constant ionic s trength were analyzed. As an example, a model system Hg/[H2O + mcKBr (I - m)cKF] was considered. It was shown that with the charge transfe r coefficient changing from lambda = 0 to lambda = -0.2 the frequency dispersion of capacitance becomes more pronounced. In consequence, com putations of the specific adsorption of anions by the Hurwitz-Parsons method become less accurate; this is caused by the nonequilibrium natu re of the original differential capacitance curves. Within the framewo rk of the Grahame-Parsons model, the calculations of equilibrium and n onequilibrium capacitance for lambda = const not-equal 0 were shown to be formally equivalent to the calculations for lambda = 0 but with tw o modified adsorption parameters. Thus, this model cannot be used for calculating lambda from experimental data.