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Research Publications (Applied Sciences)

Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/213

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Author: search.filters.author.Singh, SangeetaSubject: search.filters.subject.Sound velocity

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    Effect of temperature on density, sound velocity, refractive index and their derived properties for the binary systems (heptanoic acid + propanoic or butanoic acids)
    (Elsevier, 2014-06-14) Bahadur, Indra; Naidoo, Paramespri; Singh, Sangeeta; Ramjugernath, Deresh; Deenadayalu, Nirmala
    In this work, the effect of temperature on density (q), sound velocity (u), refractive index (n) and their derived properties for carboxylic acid mixtures was studied. The thermophysical properties: density, sound velocity and refractive index were measured over the entire composition range at T = (293.15, 298.15, 303.15, 308.15 and 313.15) K and at p = 0.1 MPa for the binary systems (heptanoic acid + propa-noic or butanoic acids). The mass fraction of water was found to be unusually large and could not be reduced further. The Lorentz–Lorenz approximation was used to predict the density from refractive index or the refractive index from density of the binary mixtures. Sound velocity mixing rules were applied to the experimental sound velocity data. Excess molar volumes, VEm; isentropic compressibilities, js, excess isentropic compressibilities, jsE, and deviation in refractive indices, Dn, were also calculated from the experimental data. The Redlich–Kister polynomial equation was fitted to the excess properties and the deviation in refractive index data. Thermophysical properties are useful in understanding the intermolecular interactions between the components of mixtures.
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    Influence of alkyl group and temperature on thermophysical properties of carboxylic acid and their binary mixtures
    (Elsevier B.V., 2014-06-30) Bahadur, Indra; Deenadayalu, Nirmala; Naidoo, Paramespri; Ramjugernath, Deresh; Singh, Sangeeta
    n this work, volumetric, acoustic and refractive index methods have been used to study the interactions between carboxylic acids mixtures as a function of temperature and concentration. The density (r), sound velocity (u), refractive index (n) of butanoic acid, pentanoic acid and heptanoic acid and their binary systems (butanoic or heptanoic acid + pentanoic acid) have been measured at 293.15, 298.15, 303.15, 308.15 and 313.15 K and at p = 0.1 MPa. The Lorentz–Lorenz approximation and sound velocity mixing rules were used to test the accuracy of the experimental data. The derived properties such as excess molar volumes, VEm, isentropic compressibilities, ks, excess isentropic compressibilities, ksE, and deviation in refractive indices, Dn, were also calculated. The Redlich–Kister polynomial equation was used to fit the excess/deviation properties. These results are useful for describing the intermolecular interactions that exist between the components in mixtures. This work also tests various sound velocity mixing rules to calculate the sound velocity of the binary mixture from pure component data, as well as examine the use of the Lorentz–Lorenz approximation to predict density from refractive index and vice versa.