Interactions in l-alanine–/l-proline–/l-valine–/l-leucine–aqueous KCl/KNO3 systems at different temperatures: An isentropic compressibility study

Ultrasonic velocity and density values of amino acids: l-alanine/l-proline/l-valine/l-leucine in 2.0 M aqueous KCl and 2.0 M aqueous KNO3 solutions have been measured for several concentrations of amino acids at different temperatures: 298.15, 303.15, 308.15, 313.15, 318.15 and 323.15 K. Using ultrasonic velocity and density data, the thermodynamic parameters such as isentropic compressibility (κs), change in isentropic compressibility (Δκs) and relative change (Δκs/κ0) in isentropic compressibility have been computed. The trends in the behaviour of κs, Δκs and Δκs/κ0 with changes in the concentration of amino acids/zwitterions as well as in temperature have been discussed in terms of zwitterions–ions, zwitterions–water dipoles, ions–ions, ions–water dipoles intermolecular/interionic interactions operative in the said systems.