Osmotic and activity coefficients of dilute aqueous solutions of the series Me4Ni to MeBu3NI at 298.15 K

Osmotic coefficients of dilute aqueous solutions of Me4NI, Me3BuNI, Me2BU2NI and MeBu3NI were determined by the isopiestic method at 298.15K. A gravimetric isopiestic vapor pressure technique was used. The osmotic coefficients of tetra-alkyl-ammonium solutions were analyzed with the Debye-Huckel limiting law. The results show that the osmotic coefficient varies in the following way: Me4NI>MeBu3NI>Me2Bu2NI>Me3BuNI. The negative deviation of activity coefficients values from the Debye-Huckel limiting law was interpreted in terms of ion-pair formation. The set of Pitzer parameters b = 1.2 and eel = 2.0 was used. The results were fitted to the Pitzer model and the parameters beta(0), beta(1) and C phi were calculated. beta(0) and beta(1) were analyzed in terms of ion-ion interactions and ion-solvent interactions. (C) 2008 Elsevier B.V. All rights reserved.