Excess molar enthalpies of ternary mixtures (dibutyl ether or dipropyl ether + 2,2-dimethylbutane + 2,3-dimethylbutane) at the temperature 298.15 K
Highlights
► The excess enthalpies of the (DNBE or DNPE + 22DMB + 23DMB) systems at 298.15 K have been measured. ► The measured excess enthalpies are all positive. ► The Libermann–Fried model can be used to correlate the excess enthalpies of the constituent binary systems. ► The Libermann–Fried model can be used to predict with confidence the excess enthalpies of the ternary systems.
Introduction
Oxygenated gasolines not only reduce the emission of greenhouse gases but also increase the anti-knocking properties of the automotive fuels. In this connection, the use of ethers as gasoline blending agents has gained considerable interests [1]. The thermodynamic properties of the mixtures involving gasoline-component hydrocarbons and ethers are therefore of practical importance. Earlier studies of the excess enthalpies for the (ether + n-alkane) systems include that made by Wang et al. [2] for the (dipropyl ether + n-hexane) system at (T = 298.15 K) and that reported by Marsh et al. [3] for the (dibutyl ether + n-hexane) system at {T = 298.15 and 308.15) K}. More recently, Montero and coworkers [4], [5] have measured the excess enthalpies for the (dibutyl ether + benzene) and (dibutyl ether + cyclohexane) systems at {T = (298.15 and 313.15) K}. However, it appears that there are no excess enthalpy data for any of the (dipropyl ether + hexane isomer) and (dibutyl ether + hexane isomer) systems. As a continuation of our project for studying the thermodynamic properties of mixtures containing ethers and hydrocarbons, the excess molar enthalpy values for the ternary systems comprised of either dibutyl ether (DNBE) or dipropyl ether (DNPE), and two branched hexane isomers: 2,2-dimethylbutane (22DMB) and 2,3-dimethylbuthane (23DMB) at (T = 298.15 K) and atmospheric pressure conditions have been measured.
Section snippets
Experimental
The DNPE, 22DMB, and 23DMB were obtained from Alfa Aesar. The mole fraction purities of these chemicals, as specified by the manufacturer and verified by means of gas chromatography in this laboratory, exceeded 0.990. The DNBE was obtained from Sigma–Aldrich and had a mole fraction purity of at least 0.999. Apart from degassing, all of the components were used without further purification. Densities ρ(T = 298.15K)/(kg · m−3) measured by means of an Anton-Paar densimeter (DMA-5000M), were 763.806,
Results and discussion
Excess molar enthalpies for the {22DMB (1) + 23DMB (2)} system at T = 298.15 K have been reported previously [13]. Experimental values for the binary mixtures {DNBE (1) + 22DMB (2)}, {DNBE (1) + 23DMB (2)}, {DNPE (1) + 22DMB (2)}, and {DNPE(1) + 23DMB (2)} at T = 298.15 K are summarised in table 1. The smoothing function used to represent the experimental data has the formThe coefficients in this equation were determined by means of the method of
Acknowledgement
The financial support of the Natural Sciences and Engineering Research Council of Canada (NSERC) is gratefully acknowledged.
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