Determination of Wada Constant, Rao’s Constant, Compressibility Andviscosity of A Cholesteric Liquid Crystal Solution at Various Temperatures Anita Kanwar and Pritee Mhatre VES College of Arts, Science and Commerce, Department of Physics, Sindhi society, Chembur, Mumbai 400071. ABSTRACT: The ultrasonic waves having different frequencies propagate through the liquid crystal solution with different velocities at various temperatures. This fact helps in studying physical and chemical properties of Cholesteric liquid crystal (CLC) of different concentration at various temperatures. We in our laboratory have found out Acoustic Impedance, Rao’s constant, Adiabatic Compressibility,Wada constant,Van der Waals’ constant, Free Volume, Internal pressure andClassical Absorption Co-efficientof CLC solutionof different concentration. The measurements were made at various temperatures using Ultrasonic interferometer working at the frequencies 3MHz and 5MHz. The results so obtained are analyzedto see the effect temperature, concentration and transition of CLC into various mesophases. It is observed that when the miscibility is high and the solution is highly homogeneousthe values of the parameters change drastically showing the change in the mesophases at phase transition temperatures. INTRODUCTION: Cholesteryl Pelargonate (CP) a CLC [1] having molecular formula C 36 H 62 O 2 and molecular weight of 526.88 g/mol as obtained from Sigma –Aldrich is used in preparation of the samples. The phase transition temperatures of CLC, CP were obtained using the Fabryperot scattering studies (FPSS) technique [2]. Homogeneous mixture of Toluene and CP [3] having various concentration is used as a sample to study the effect of temperature and concentration on the physical and chemical parameters. We have determined the Wada constant, Rao’s constant, compressibility and viscosity [4-5] of the solution at various temperatures by varying concentration of the solution. Ultrasonic velocities for the solutions of different concentrations were measured by varying the temperature using indigenously designed thermometer. The ultrasonic interferometer (Mittal enterprises, India; Model: F-80X) was used for the measurements of velocity of ultrasonic waves in the solvent and solution. It consists of a high frequency generator and a measuring cell and the measurements were made at two different frequencies viz3MHz and 5MHz. The least count of micrometer measuring cell is 0.01mm. The ultrasonic velocity has an accuracy of ± 0.5%. It is used to find the Acoustic Impedance, Rao’s constant, Adiabatic Compressibility,and Wada constant. The viscosity was measured by Oswald’sviscometer. It is used to find Van der Waals’ constant, Free Volume, Internal pressure andClassical Absorption Co-efficient of the five samples prepared in the laboratory. 2080 International Journal of Engineering Research & Technology (IJERT) Vol. 3 Issue 1, January - 2014 ISSN: 2278-0181 www.ijert.org IJERTV3IS10714