Practical Feasibility of Arago-Biot and Lorentz-Lorenz Theory Through Variation of Refractive Index of Typical Binary Liquid Mixtures Employing Low-Cost Experimental Setup

Optical properties of the solutions comprising of two or more miscible liquids have been of immense interest both in the area of chemical and physical sciences. To date, there are reports on studies regarding different combinations of binary liquid mixtures. However, the experiments involved are either high-ended or using sophisticated instrumentation. Our prime objective is to set up a simple laboratory arrangement to estimate the refractive index of typical binary-liquid mixtures obtained by proportionate variations in combinations selecting from benzene, ethyl acetate, tetrahydrofuran, and water; without involving high-standard instrumentation or expensive laboratory setups. In the present study, we adopted a basic method to determine the refractive index of pure liquids of low polarity, like, benzene (C6H6) and tetrahydrofuran or THF (C4H8O) and of high polarities, such as ethyl acetate or EtOAc or EA (C4H8O2), and water (H2O) and also their binary homogeneous mixture with high accuracy. Our experimental data involving variation of refractive index with molar volume fraction matched very well with theoretical interpretations by Arago-Biot and Lorentz-Lorenz equation. In our results, density corrections have been neglected as we have chosen non-volatile solvents.