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

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 (V-phi), isentropic compressibility of solution (kappa(S)), apparent molar isentropic compressibility (K-S,K-phi) of solute, limiting apparent molar volume (V-phi(0)), limiting apparent molar volume of transfer (Delta V-tr(phi)0), limiting apparent molar expansibility (E-phi(0)), limiting apparent molar isentropic compressibility (K-S,phi(0)) and limiting apparent molar isentropic compressibility of transfer (Delta K-tr(S, phi)0). 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.