Ultrasonic Velocities and Densities of l-Histidine or l-Glutamic Acid or l-Tryptophan or Glycylglycine + 2 mol·L−1 Aqueous KCl or KNO3 Solutions from (298.15 to 323.15) K

Abstract

Ultrasonic velocity and density values of l-histidine or l-glutamic acid or l-tryptophan or glycylglycine + 2 mol·L−1 aqueous KCl or 2 mol·L−1 aqueous KNO3 solution have been measured as functions of amino acid or dipeptide concentration and temperature from T = (298.15 to 323.15) K. Using ultrasonic velocity and density data, the thermodynamic parameters isentropic compressibility (κs) and change in isentropic compressibility values have been computed. The κs values decrease with an increase in the amino acid/dipeptide concentration as well as with temperature of the systems under investigation. The decrease in κs values with an increase in concentration of amino acid/dipeptide in aqueous solutions of KCl and KNO3 has been ascribed to an increase in the number of incompressible zwitterions in the solutions.