Densities and kinematic viscosities of molten mixtures of nickel(II) chloride in tetra-n-butylammonium iodide have been measured as functions of temperature and composition. The data on the kinematic viscosity have been analyzed using both Arrhenius and non-Arrhenius type equations. The heat of activation, the entropy of activation, and the free energy of activation for viscous flow have been computed. At higher concentrations a slight tendency towards non-Arrhenius viscous behaviour is observed. The free energy of activation helps in describing the overall composition dependence of kinematic viscosity.

SynopsisThe environmental relaxation model was applied successfully to explain the temperature dependence of viscosity, conductance, and the Walden product of molten Ca(N0&-3.91H20 + NiCI:! system in the non-Arrhenius region. This model was applied to pure melts, binary molten salt systems with ideal solutions marked by the absence of complex ions, and systems in which octahedral or tetrahedral complexes are formed. The values of the glass transition temperature obtained from the free volume and environmental relaxation models are in good agreement. The values of apparent activation energies for viscous and conductance flows derived from these two models are also comparable.Arrhenius region. The molten Ca(N03)2-3.91HzO + NiCl2 system was chosen for a detailed study of the applicability of ERM. Ni2+ forms an octahedral complex species, Ni(H20)&12, in molten calcium nitrate tetrahydrate.6 The reported viscosities 7 and equivalent conductances A of this system in the temperature range 298-343 K and composition range 0.0-6.49 mole % of Ni2+ (the maximum solubility of anhydrous NiCl2 in molten calcium nitrate tetrahydrate) were considered here for data analysis. This analysis was also made for pure melt, ideal molten salt mixture, and nonideal melts that contain octahedral or tetrahedral complex ions.