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Refractive Index, Surface Tension, and Density of Aqueous Mixtures of Carboxylic Acids at 298.15 K

2006; American Chemical Society; Volume: 51; Issue: 4 Linguagem: Inglês

10.1021/je060084c

1520-5134

Karla Granados, Jesús Gracia‐Fadrique, Alfredo Amigo, Ramón Bravo,

Chemical Thermodynamics and Molecular Structure

Refractive indices (n), densities (ρ), and surface tensions (σ) for {formic acid, acetic acid, propionic acid, or butyric acid + water} mixtures at 298.15 K and normal atmospheric pressure have been determined as a function of mole fractions. From the experimental data, excess molar volumes (V E) and deviations of refractive index from linear behavior (Δnφ) have been calculated. The magnitude of these experimental quantities is discussed in terms of nature and type of intermolecular interactions in binary mixtures. Besides, the interpretation of the ratio of molar volume to molar refraction V/R as a measure of the degree of free volume appears to be a useful tool for qualitative considerations concerning volumetric and refractometric data. To analyze the behavior of surface tensions, the Extended Langmuir (EL) model was used.