Ultrasonic studies in simple liquids and binary mixtures
This thesis is concerned with the study of four topics. These are:- 1. Rotational Isomerism in Methylpentanes and Methylhexanes The rotational isomerism in methylpentanes and methylhexanes has been studied using the ultrasonic relaxation technique. The observed conformational energetics obtained are compared with those predicted on the basis of non-bonded van der Waals' interaction between neighbouring groups. In general, the values of the activation and energy difference obtained from experiment are in good agreement with those obtained from the theory. The adiabatic compressibilities and other ultrasonic parameters indicate that the propagation of sound in these liquids is controlled by the nature of the molecular structure and the effects of the basic shapes of the molecules on the intermolecular interactions. 2. Mixtures of Dimethylpentanes in n-Heaxadecane Studies of the physical and acoustic properties of binary mixtures of dimethylpentanes and n-hexadecane at 298.15K indicate a concentration dependent phenomenon. The observed acoustic attenuation is associated with a rotational isomeric process and a clustering of the molecules in the mixture. 3. Mixtures of Isomeric Octanols in n-Octane Studies of the binary mixtures of isomeric octanols with n-octane indicate that the observed volume, adiabatic and acoustic excesses are a consequence of competing effects of the alkane chain taking up the 'free' volume in the system and the disturbance of the distribution between cyclic, linear structures and monomer forms in the mixtures. 4. N-Formylmorpholine-Water Mixtures The acoustic, p13sC nmr spectra and physical properties of N-formylmorpholine and its aqueous solutions indicate that N-formylmorpholine is more planar than its N-alkyl analogues and this planarity is increased by the presence of traces of water. This explains the increased efficiency in the extraction of aromatics from petroleum feedstocks.