Resistivity–viscosity relationship in liquid–liquid critical mixtures with added ions

Precise resistivity ρ (Ω cm) and viscosity η (10−2 P) measurements for isobutyric acid–water (IBAW) critical mixtures with added K+ and Cl− ions have been performed in the Arrhenius temperature domain of the electrolyte. From the activation energy, the resistivity–viscosity relation reveals a fraction power character over the whole range of parameters investigated. To analyze our data we have used an exponential formula derived from the equivalent Arrhenius law: ρ/T is proportional to (η/T)R, where R = Eρ/Eη is the ratio between the resistivity and viscosity activation energies. In the case of the pure system (IBAW), the value of R is in vicinity of 1, but when the salt is added, the ratio R shows dependence on the (K+, Cl−) concentrations: 0.6 < R < 1. The domain of the validity of R is in conformity with the theoretical prediction. The Coulombic interaction is the origin of the deviation.