Isothermal binary and ternary diffusion in the system (C2H5)4 NBr–KBr–H2O

Abstract

Isothermal free diffusion in the binary systems KBr–H₂O, (C₂H₅)₄NBr–H₂O and in the ternary system (C₂H₅)₄NBr–KBr–H₂O has been studied at various compositions with a precision single-lens Gouy interferometer. For the binary systems, the observed diffusion coefficients have been compared with those of similar compounds and, in the case of (C₂H₅)₄NBr, have been compared with theoretical values predicted from activity coefficient behaviour for which a parameter-fitting least-squares approach has been used to determine the activity coefficient variation with concentration. Ternary coefficients have been analysed qualitatively in terms of ionic attractions in the solution and have been compared with the binary coefficients at similar concentrations. The Onsager Reciprocal Relation has been verified for one composition of the ternary system, but the calculations differ from previous tests in that the more versatile Scatchard approach to multicomponent solutions has been used rather than Harned's rule.