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Ultrasonic technique is a powerful tool for the study of inter and intra-molecular interactions in a mixture. It is a non-destructive testing tool. Low amplitude ultrasonic propagation, as is used for the present work, does not change the molecular structure of a liquid. This technique is the most preferred one as it will not allow local heating. Liquid mixtures behave critically with the change in temperature and concentration in any of the component. In the present work, physical properties of mixture of cyclohexane and methanol are studied using ultrasonic pulse echo technique. Ultrasonic attenuation is measured to study mixture of cyclohexane and methanol. Present system is operated at 5 MHz frequency and the mixture is studied in the controlled temperature environment by using Thermostat (Julabo F32) with an accuracy of ±0.10C. Non-linearity in ultrasonic attenuation with maxima and minima is observed due to concentration fluctuations in the given mixture.

Recently, study of physical properties of the liquid mixtures, their nature and behavior with change in frequency, temperature or concentration has gained interest. In the present work, ultrasonic velocity and attenuation measurements have been carried out in the binary mixture of nitrobenzene and ethanol using pulse echo technique in the temperature range of 274.15K-308.15K maintaining the temperature of the sample with an accuracy of ±0.1°C. It is observed that the mixture of nitrobenzene and ethanol shows maximum absorption at 277.15K at 0.27 moles of Nitrobenzene in the binary mixture. Critical nature of the mixture revealed by ultrasonic absorption indicates the molecular interaction between two liquids and attributes due to the fluctuation in the concentration.

In the present work, positional Isomerism is studied in the binary mixtures of n-propyl alcohol and Iso-propyl alcohol in nitrobenzene as the common solvent. Ultrasonic velocity and attenuation measurements using pulse–echo technique operated at 10 MHz have been taken at various concentrations of both alcohols in nitrobenzene, from 283.15K - 293.15K. It is observed that both the systems exhibit critical nature and show non-linear variation both in ultrasonic velocity of propagation and attenuation. Ultrasonic attenuation at lower concentrations of n-propyl alcohol in nitrobenzene reveals the dominant structural relaxation as compared to that of Iso-propyl alcohol in nitrobenzene.