Nitrate Selectivity of Ion-Exchange Resins and of Their Model Compounds. II. Viscosity and Density of Benzyltrialkylammonium Salts in Aqueous Solution and 14N N.M.R. Relaxation of the Nitrate Ion

Abstract

The densities and viscosities of benzyltrialkylammonium chlorides and nitrates were determined in aqueous solution; the alkyl substituents were methyl, ethyl, propyl , butyl and pentyl . The concentration dependence of the 14N nuclear spin relaxation of the nitrate ion was used to find ion pair association constants for comparison with those derived from conductivity measurements (Part I). Density measurements were used to determine partial molar volumes, and viscosity measurements to find hydrodynamic volumes of the solutes. With the assumption of additivity of ionic volumes, cationic volumes calculated from the two series of chloride and nitrate salts agreed well. The increase in the ratio of hydrodynamic to partial ionic volumes with increasing chain length of the alkyl substituent was interpreted as a corresponding increase in hydrophobic hydration.