Isopiestic determination of the osmotic and activity coefficients of dilute aqueous solutions of the series MeEt3NI to HepEt3NI at 298.15 K

The osmotic coefficients of MeEt3NI, Et4NI, PrEt3NI, BuEt3NI, PenEt3NI, HexEt3NI and HepEt3NI in dilute aqueous solutions were determined by the isopiestic method at 298.15 K. The osmotic coefficients of tetra-alkyl-ammonium iodides in aqueous solutions were analyzed by comparing them with calculated values from the Debye–Hückel limiting law. The osmotic coefficient data of MeEt3NI, PrEt3NI and BuEt3NI show positive deviations from the Debye–Hückel limiting law. The osmotic coefficient data of HexEt3NI, Et4NI, PenEt3NI and HepEt3NI show negative deviations from the Debye–Hückel limiting law. The non-ideal behavior of these electrolyte systems was satisfactorily correlated by the Pitzer ion interaction model with two adjustable parameters β0 and β1.