Acoustical and thermodynamical studies of ion-ion and ion-solvent interactions of some a-amino acids in purely aqueous and aqueous tetraethylammonium bromide medium at 303.15K

R. Palani* and S. Kalavathy

Department of Physics, D.D.E, Annamalai University, Annamalainagar (India).

Received on August 08, 2009 and accepted on October 15, 2009

ABSTRACT

Density (r), viscosity (h) and ultrasonic velocity (U) of L-threonine, L-leucine and L-histidine in water and aqueous tetraethylammonium bromide (0, 0.05 and 0.1 mol×dm–3) have been measured at 303.15K. These measurements have been used to calculate some important parameters viz., adiabatic compressibility (b), molar hydration number (nH), apparent molar compressibility (), apparent molar volume (), limiting apparent molar compressibility (jV0) and their constants (,) and transfer volume (). The viscosity data have been analysed on the basis of the Jones-Dole equation, the viscosity A and B coefficients have been evaluated. The variation of these parameters with concentrations clearly suggests the role of alkyl cation on the ion-solvent interactions in aqueous medium. The structural influence of the large cations of quaternary ammonium salts upon solvent is also taken into consideration.

Keywords : Amino acids, tetraethylammonium bromide, apparent molar volume, apparent molar compressibility