Molecular interaction studies of caffeine in aqueous metal chloride solutions at 308.15 K

Abstract

Ultrasonic speed (u), density (d) and viscosity (η) of caffeine in aqueous solutions of potassium chloride, sodium chloride, magnesium chloride and calcium chloride have been measured at 308.15 K. From these data, thermodynamic interaction coefficient, isentropic compressibility (β s ), intermolecular free length (L f ), apparent molar volume (Φ v ), relative association (R A ) and acoustic impedance (Z) have been computed. All the derived parameters are correlated with the molar composition of solutions. Depending on the molecular interactions and the nature of the solutions show the change in structure of solvent when solute is added to it. The viscosity coefficients A and B of Jones-Dole equation have been determined and employed to throw light on the mechanism of solute-solute and solute-solvent interactions.