THERMODYNAMIC STUDIES ON N,N,N-OCTYLOCTYLDIMETHYL AMMONIUM-CHLORIDE IN WATER-UREA MIXTURES

The densities, heat capacities and enthalpies of dilution at 298 K and the osmotic coefficients at 310 K were measured for N,N,N-octyloctyld imethylammonium chloride (OOAC) in aqueous urea solution as a function of urea (m(u)) and surfactant (m(s)) concentrations in order to deter mine, in comparison with the lower homologue N,N,N-pentyloctyldimethyl ammonium chloride, OPAC, the influence of the hydrophobic tail on the properties of a double-chain surfactant in the presence of an additive like urea. From specific conductivity data, the critical micelle conc entration (cmc) and the degree of the counterion dissociation (beta) h ave been calculated. From the thermodynamic data, the molar apparent v olumes, V-phi, heat capacities, C-phi, and apparent molar relative ent halpies, L phi, were derived as a function of m(u) and m(s) at 298 K.