Ultrasonic absorption and spectroscopic studies of aqueous systems.

This thesis is concerned with the theoretical and experimental aspects of ultrasonic absorption and vibrational spectroscopic studies of aqueous solutions. Emphasis is placed upon the role of water in those systems. Measurements of ultrasonic absorption in the systems methyl cyanide + water and acetone + water are reported over the frequency range 200 kHz to 230 MHz. The construction of an apparatus for measurement of ultrasonic absorption over the frequency range 200 to 1500 kHz is described. Ultrasonic velocity measurements are reported over a wide range of mixture compositions and temperatures for the system methyl cyanide + water. Current theoretical models for ultrasonic absorption in binary liquid mixtures are reviewed and one model, that due to Romanov and Solovyev, is examined in detail. The model of Romanov and Solovyev is set down analytically in a convenient form for direct comparison with other models. The treatment of Romanov and Solovyev, together with the discrete relaxation model, is examined critically for the systems t butyl alcohol + water, acetone + water, methyl cyanide + water. In addition, the Romanov-Solovyev theory, is extended to treat electrolyte solutions and, in its extended form, is applied with some success to the systems tetra-alkylamnonium bromide + water, and urea + water. The results of these applications reveal an important link between thermodynamic excess functions and ultrasonic absorption. Infra-red and Raman spectroscopic studies of aqueous solutions of electrolytes and organic solutes are reported. Particular attention is given to the study of metal perchlorate solutions. An attempt is made to distinguish between current models for the behaviour of salts when dissolved in HOD/H2O solutions, with special reference to the influence of anions and cations on band parameters. An ALGOL computer program for band deconvolution is described. The design of a thermostatted Raman cell-holder for the CODERG Raman spectrometer is given.