MODEL REPRESENTATION OF ELECTROLYTE-SOLUTIONS BASED ON MASS SPECTROGRAPHICAL DATA

A model representation of electrolyte solutions is proposed. Two assum ptions are used: (a) There are k equivalent potential wells around eac h ion in the solution; (b) the probability of the occupation of the po tential well by a solvent molecule is p<1. According to these assumpti ons, the probabilities w(b)(n) Of simultaneous occupation of n wells ( n = 0,1,2,..,k) by solvent molecules are the terms of the binomial (p + q)(k), where q =(1 - p) is the probability that the potential well i s empty. In consequence to the motion of the solvent molecules between the potential wells, there is an equilibrium distribution of the solu tion ions (cations and anions) with respect to a degree of solvation. The binomial terms w(b)(n) satisfactorily correlate with the correspon ding terms w(e)(n) of the experimental distributions of mass spectral line intensities of ions and ion clusters of alkaline metals evaporate d from aqueous and aqueous-ethanol solutions into vacuum by means of a strong electric field. The dependence of the probability p on the sol ution temperature derived from the presented model is experimentally c onfirmed for aqueous-ethanol solution of NaI in the temperature range of 219-248 K. The enthalpy changes for the detachment of one or two et hanol molecules from Na+Et-m,(H2O)(n) ion clusters in solution (Et is ethanol, m,n=0,1,2,...) were obtained from experiments. The mechanism of the field evaporation of ions from solutions is discussed. The expr ession for the heat of evaporation for ion clusters is deduced. (C) 19 98 American Institute of Physics.