Volumetric and ultrasonic studies of some amino acids in binary aqueous solutions of MgCl2·6H2O at 298.15 K

✍ Scribed by Amalendu Pal; Suresh Kumar

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 188 KB
• Volume: 121
• Category: Article
• ISSN: 0167-7322
• DOI: 10.1016/j.molliq.2004.12.003

✦ Synopsis

Apparent molar volumes (V / ) and adiabatic compressibilities (K /,s ) of glycine, l-alanine and l-valine in binary aqueous solutions of MgCl 2 d 6H 2 O (0.1-0.8 mol kg À1 ) have been determined at 298.15 K from precise density and sound speed measurements. Partial molar volumes (V / 0 ) and partial molar adiabatic compressibilities (K /,s 0 ) of these amino acids at infinite dilution were evaluated. These values are used for calculating the number of water molecules hydrated (n H ) to the amino acids. Group contributions for the partial molar volumes and adiabatic compressibilities have been determined from the amino acids. Transfer volumes (DV / 0 ) and transfer adiabatic compressibilities (DK /,s 0 0) at infinite dilution from water to aqueous magnesium chloride solutions have been calculated. Transfer parameters have been interpreted in terms of solute-cosolute interactions on the basis of a cosphere overlap model. Pair and triplet interaction coefficients have also been calculated from transfer parameters. All these results indicate that hydrophillic-ionic group interactions are predominant over hydrophillic-hydrophobic group interactions over the whole concentration range of magnesium chloride and decrease with the increase in size of the side chain of amino acids.