Effect of Temperature on the Volumetric Properties of the l -Alanine (1) + KCl (2) + H2O (3) System

The effect of temperature on the volumetric properties of the l -alanine (1) + KCl (2) + H 2 O (3) system has been studied by experimentally measuring densities and speeds of sound in the temperature range 283.15 K to 313.15 K. Apparent molar expansibilities, φ E, and the temperature derivative of the apparent molar compressibility, (∂φ K /∂ T ) P, were calculated for l -alanine in aqueous KCl and for KCl in aqueous l -alanine. The positive values of expansibilities and (∂φ K /∂ T ) P are explained in terms of interactions between charged end groups and the ions. The derived properties are analyzed in terms of a two-parameter (λ‘ and λ‘ ‘) model recently proposed by us. We have also attempted to examine the temperature and concentration dependence of such interaction parameters by studying the volumetric properties of the l -alanine (1) + KCl (2) + H 2 O (3) system.