THERMAL-DIFFUSION OF WEAK ELECTROLYTES - I - A MODEL FOR THE DETERMINATION OF THE SORET COEFFICIENT OF WEAK ELECTROLYTES

A new model is developed for determination of the Soret coefficient an d the enthalpy of transport for weak (p(k) similar to 4-5) 1:1 electro lytes in aqueous solutions. As an example the model is applied for ace tic acid-water system. In the model the effects both of the thermal di ffusion and the displacement of the dissociation equilibrium with temp erature and concentration are taken into account. The Soret coefficien t is calculated from the enthalpies of transport of the anion which wa s taken identical to that of the molecular acid. The calculated Soret coefficient of the acetic acid (ionic and molecular form together) exh ibits a maximum value of 8.3.10(-3) K-1 at the molality of 0.025 mol k g(-1).