Volumetric and acoustic studies of aqueous l-arginine·HCl and l-proline in electrolytic and non-electrolytic solutions at various temperatures

Abstract

Densities and speed of sound of l-arginine hydrochloride and l-proline within the concentration range (0.03–0.2) mol.kg−1 in water and in aqueous NaCl and Urea are determined between temperatures 288.15 K and 318.15 K and at one atmospheric pressure. Densities and speeds of sound have been used to calculate apparent molar volume of solute (Vφ), isentropic compressibility of solution (κS), apparent molar isentropic compressibility (KS,φ) of solute, limiting apparent molar volume (Vφ0), limiting apparent molar volume of transfer (ΔtrVφ0), limiting apparent molar expansibility (Eφ0), limiting apparent molar isentropic compressibility (KS,φ0) and limiting apparent molar isentropic compressibility of transfer (ΔtrKS,φ0). These results are then interpreted in terms of intermolecular interactions. The concentration dependencies of the calculated quantities, their limiting values and temperature characteristics are discussed in terms of solute - solvent and solute - solute interactions at experimental conditions.