ASYMMETRIC ELECTROLYTE IN MIXTURE WITH A NEUTRAL COMPONENT - EFFECTS OF COUNTERION CHARGE

The equilibrium structure and thermodynamics of a multicomponent primi tive model mixture consisting of a single asymmetric electrolyte and a neutral particle are studied as a function of the concentration of th e neutral species, and for counterion valencies -1, -2 and -3. The mod el, relevant for 'crowding reaction' processes in many biological syst ems is considered within the context of the symmetric Poisson-Boltzman n, the modified Poisson-Boltzmann, and the hypernetted chain theories. An important common prediction of the theories is that, at higher con centrations of the neutral species and for all valencies, there is an attractive force between the macroions. A comparison of the pair distr ibution functions and thermodynamics reveals the theories to be in sem iquantitative or better agreement overall, with the modified Poisson-B oltzmann and the hypernetted chain results being generally closer to e ach other.