Interactions in l-alanine–/ l-proline–/ l-valine–/ l-leucine–aqueous KCl/KNO 3 systems at different temperatures: An isentropic compressibility study

Abstract

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 KNO 3 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 (Δ κ s) and relative change (Δ κ s/ κ 0) in isentropic compressibility have been computed. The trends in the behaviour of κ s, Δ κ s and Δ κ s/ κ 0 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.