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 (κ_s), change in isentropic compressibility (Δκ_s) and relative change (Δκ_s/κ₀) in isentropic compressibility have been computed. The trends in the behaviour of κ_s, Δκ_s and Δκ_s/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.