RELATIONSHIP BETWEEN DIFFUSIVITY AND VISCOSITY FOR SUPERSATURATED ELECTROLYTE-SOLUTIONS

Highly supersaturated electrolyte solutions are prepared and studied e mploying an electrodynamic levitator trap (ELT) technique. Very high s upersaturations were achieved and studied. The theoretical study is ba sed on the development of the Cahn-Hilliard formalism for electrolyte solutions. A correspondence of 96-99 % between theory and experiment f or all the solutions studied was achieved and reported earlier [Izmail ov, Myerson and Na, Phys. Rev. E 52 (1995) 3923]. The theoretical appr oach suggested in this study for thermodynamics of supersaturated elec trolyte solutions is further developed in order to describe the transi ent and stationary limits of the metastable state relaxation. Knowledg e of these limits has allowed derivation of the fluctuation-dissipatio n theorem (FDT) for supersaturated electrolyte solutions by specifying a time-dependent product of macroscopic mobility (inverse viscosity), describing momentum dissipation, and microscopic diffusivity, describ ing local fluctuations of solute concentration. It is understood from general relationships of non-equilibrium thermodynamics that this prod uct has a maximum at saturation point and is equal to zero at spinodal point. Further analysis of the FDT has revealed that the product has another particularity: a local minimum in the deeply undersaturated re gion of solute concentrations. Numerical analysis of the FDT has been carried out for the supersaturated, binary, electrolyte symmetric solu tions such as NaCl, NaBr, KCI, KRr and NH4Cl.