Department of chemistry
The University of British Columbia
Faculty in University of British Columbia
Dr. Koga's group has introduced a new approach to the thermodynamic studies of aqueous solutions. Methods of measuring various thermodynamic quantities differentially were devised. Using these, the inter-molecular interaction, the key quantity in the so-called "many-body problem", can be evaluated experimentally. For the aqueous solutions of 2-butoxyethanol, a common model system for solutions of biochemical importance, it was pointed out that there are regions in the composition-temperature field, in each of which the "mixing scheme" is qualitatively different. Furthermore, the transition from one mixing scheme to the other was found much more subtle than the normal phase transition. At the boundary separating two mixing schemes, the thermodynamic quantities that are proportional to the third derivatives of the Gibbs energy showed anomalies. (In contrast, the normal phase transitions are accompanied by anomalies in the second derivatives; heat capacity, compressibility etc.) The boundary separating the two regions has been dubbed as the "Koga linien" by Danish collaborators.