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Comment on “Density, dynamic viscosity, excess property and intermolecular interplay studies for 1,4-butanediol + dimethyl sulfoxide binary mixture”
Journal of Molecular Liquids 272 (2018) 237–238
Contents lists available at ScienceDirect
Journal of Molecular Liquids journal homepage: www.elsevier.com/locate/molliq
Short Communication
Comment on “Density, dynamic viscosity, excess property and intermolecular interplay studies for 1,4-butanediol + dimethyl sulfoxide binary mixture” William E. Acree Jr a,⁎, Fleming Martínez b a
Department of Chemistry, University of North Texas, Denton, TX 76203, USA Grupo de Investigaciones Farmacéutico-Fisicoquímicas, Departamento de Farmacia, Facultad de Ciencias, Universidad Nacional de Colombia -Sede Bogotá, Cra. 30 No. 45-03, Bogotá, D.C., Colombia b
a r t i c l e
i n f o
Article history: Received 14 August 2018 Received in revised form 18 September 2018 Accepted 20 September 2018 Available online 21 September 2018 Keywords: Thermodynamic properties Excess molar volumes Partial molar volumes
a b s t r a c t A polemic is given regarding the calculated volumetric properties reported by Yue and coworkers for binary mixtures containing 1,4-butanediol and dimethyl sulfoxide. The calculated excess molar volumes reported by the authors for 293.15 K are not thermodynamically consistent with the calculated partial molar volumes of the mixture components. The calculated excess molar volumes at 293.15 K are negative, while the partial molar volumes suggest that the excess molar volumes should be positive. Thermodynamic inconsistencies were found at other temperatures as well. © 2018 Elsevier B.V. All rights reserved.
In a recent paper published in This Journal Yue and coworkers [1] reported the density and kinematic viscosity of binary mixtures containing 1,4-butanediol and dimethyl sulfoxide. Measurements were performed in 5 K temperature increments from 293.15 K to 318.15 K. From the experimental density data the authors calculated the excess molar volumes, and the apparent molar volumes and the partial molar volumes of both 1,4-butanediol and dimethyl sulfoxide at each binary mixture composition. The purpose of this commentary is not to criticize the work of Yue and coworkers, but rather to point out to publishing authors, potential manuscript reviewers and journal readers one very quick way to check calculated volumetric values for errors. The excess molar volumes for 293.15 K that Yue and coworkers tabulated in Table 6 of their published paper [1] are thermodynamically inconsistent with the partial molar volumes that are reported in Table 9. The inconsistency at 293.15 K is apparent without having to perform any actual calculation. The second column of Table 9 lists the partial molar volume of 1,4butanediol, Vm,1, and partial molar volume of dimethyl sulfoxide, Vm,2. 1,4-Butanediol is denoted as component 1, and the partial molar volume of “neat” 1,4-butanediol at x1,4-butanediol = 1.0 is Vm,1 = 88.72 cm3 mol−1 at 293.15 K. As dimethyl sulfoxide is added, the mole fraction composition of 1,4-butanediol decreases and the partial molar volume of 1,4butanediol increases. The partial molar volume of dimethyl sulfoxide is located in the second half of the table. The partial molar volume of ⁎ Corresponding author. E-mail address: [email protected] (W.E. Acree).
https://doi.org/10.1016/j.molliq.2018.09.097 0167-7322/© 2018 Elsevier B.V. All rights reserved.
“neat” dimethyl sulfoxide at xdimethyl sulfoxide = 1.0 is Vm,2 = 71.00 cm3 mol−1 at 293.15 K. As 1,4-butanediol is added, the mole fraction of dimethyl sulfoxide decreases and the partial molar volume of dimethyl sulfoxide increases. With both partial molar volumes increasing above the partial molar volumes of the two “neat” co-solvents, the excess molar volume, VmE, must be positive. All of the numerical values of VmE values at 293.15 K in Table 6 are negative, hence there is an inconsistency in the calculated excess molar volumes and partial molar volumes of the two mixture components. For those that wish more of a mathematical discussion, the excess molar volume is defined as: V Em ¼ V m;mixture −V m;ideal solution
ð1Þ
the difference between the actual molar volume of the binary mixture, Vm,mixture, and the molar volume of the ideal solution at the given binary mixture composition, Vm,ideal solution. The molar volume of the binary mixture is equal to: V m;mixture ¼ x1 V m;1 þ x2 V m;2
ð2Þ
the mole fraction average of the partial molar volumes of the mixture components at the mixture mole fraction composition, and the molar volume of the binary ideal solution is equal to: V m;ideal solution ¼ x1 V m;1 þ x2 V m;2
ð3Þ
238
W.E. Acree Jr, F. Martínez / Journal of Molecular Liquids 272 (2018) 237–238
the mole fraction average of the molar volumes of the two “neat” liquid co-solvents, Vm, 1∗and Vm, 2∗, which in the present case are the partial molar volume of 1,4-butanediol at x1,4-butanediol = 1.0 and the partial molar volume of dimethyl sulfoxide at xdimethyl sulfoxide = 1.0. Combination of Eqns. 1–3 yields the following expression for calculating the excess molar volume: V Em ¼ x1 V m;1 −V m;1 þ x2 V m;2 −V m;2
ð4Þ
The excess molar volume at 293.15 K and at a mole fraction composition of 1,4-butanediol of x1 = 0.5145 is obtained by substituting the partial molar volumes of Vm,1 = 88.83 cm3 mol−1 and Vm,2 = 71.11 cm3 mol−1 into Eq. (4): V Em ¼ 0:5145ð88:83−88:72Þ þ 0:4855ð71:11−71:00Þ
ð5Þ
The calculated excess molar volume based on the partial molar volume data from Table 9 is positive, VmE = 0.11 cm3 mol−1. The authors calculated value from Table 6 is VmE = −0.0605 cm3 mol−1. Checking the authors' calculated volumetric properties at temperatures other than 293.15 K for thermodynamic consistency will require numerical calculations. For example, the partial molar volumes 1,4butanediol at 298,15 K decrease with increasing concentration of
dimethyl sulfoxide. The partial molar volume of dimethyl sulfoxide still increases with increasing 1,4-butanediol mole fraction. The excess molar volume at 298.15 K and at a mole fraction composition of 1,4butanediol of x1 = 0.5145 is obtained by substituting the partial molar volumes of Vm,1 = 88.91 cm3 mol−1 and Vm,2 = 71.42 cm3 mol−1 into Eq. (4): V Em ¼ 0:5145 ð88:91−89:00Þ þ 0:4855 ð71:42−71:31Þ
ð6Þ
The calculated excess molar volume based on the partial molar volume data from Table 9 is positive, VmE = 0.007 cm3 mol−1. The authors calculated value from Table 6 is VmE = −0.0589 cm3 mol−1. We suspect that there are other inconsistencies between the tabulated values in Tables 6 and 9. The errors that we found could have been avoided had the authors checked their calculated values for internal consistency using Eq. (4). References [1] X. Yue, L. Zhao, L. Ma, H. Shi, T. Yang, J. Zhang, Density, dynamic viscosity, excess property and intermolecular interplay studies for 1,4-butanediol + dimethyl sulfoxide binary mixture, J. Mol. Liq. 263 (2018) 40–48.
Contents lists available at ScienceDirect
Journal of Molecular Liquids journal homepage: www.elsevier.com/locate/molliq
Short Communication
Comment on “Density, dynamic viscosity, excess property and intermolecular interplay studies for 1,4-butanediol + dimethyl sulfoxide binary mixture” William E. Acree Jr a,⁎, Fleming Martínez b a
Department of Chemistry, University of North Texas, Denton, TX 76203, USA Grupo de Investigaciones Farmacéutico-Fisicoquímicas, Departamento de Farmacia, Facultad de Ciencias, Universidad Nacional de Colombia -Sede Bogotá, Cra. 30 No. 45-03, Bogotá, D.C., Colombia b
a r t i c l e
i n f o
Article history: Received 14 August 2018 Received in revised form 18 September 2018 Accepted 20 September 2018 Available online 21 September 2018 Keywords: Thermodynamic properties Excess molar volumes Partial molar volumes
a b s t r a c t A polemic is given regarding the calculated volumetric properties reported by Yue and coworkers for binary mixtures containing 1,4-butanediol and dimethyl sulfoxide. The calculated excess molar volumes reported by the authors for 293.15 K are not thermodynamically consistent with the calculated partial molar volumes of the mixture components. The calculated excess molar volumes at 293.15 K are negative, while the partial molar volumes suggest that the excess molar volumes should be positive. Thermodynamic inconsistencies were found at other temperatures as well. © 2018 Elsevier B.V. All rights reserved.
In a recent paper published in This Journal Yue and coworkers [1] reported the density and kinematic viscosity of binary mixtures containing 1,4-butanediol and dimethyl sulfoxide. Measurements were performed in 5 K temperature increments from 293.15 K to 318.15 K. From the experimental density data the authors calculated the excess molar volumes, and the apparent molar volumes and the partial molar volumes of both 1,4-butanediol and dimethyl sulfoxide at each binary mixture composition. The purpose of this commentary is not to criticize the work of Yue and coworkers, but rather to point out to publishing authors, potential manuscript reviewers and journal readers one very quick way to check calculated volumetric values for errors. The excess molar volumes for 293.15 K that Yue and coworkers tabulated in Table 6 of their published paper [1] are thermodynamically inconsistent with the partial molar volumes that are reported in Table 9. The inconsistency at 293.15 K is apparent without having to perform any actual calculation. The second column of Table 9 lists the partial molar volume of 1,4butanediol, Vm,1, and partial molar volume of dimethyl sulfoxide, Vm,2. 1,4-Butanediol is denoted as component 1, and the partial molar volume of “neat” 1,4-butanediol at x1,4-butanediol = 1.0 is Vm,1 = 88.72 cm3 mol−1 at 293.15 K. As dimethyl sulfoxide is added, the mole fraction composition of 1,4-butanediol decreases and the partial molar volume of 1,4butanediol increases. The partial molar volume of dimethyl sulfoxide is located in the second half of the table. The partial molar volume of ⁎ Corresponding author. E-mail address: [email protected] (W.E. Acree).
https://doi.org/10.1016/j.molliq.2018.09.097 0167-7322/© 2018 Elsevier B.V. All rights reserved.
“neat” dimethyl sulfoxide at xdimethyl sulfoxide = 1.0 is Vm,2 = 71.00 cm3 mol−1 at 293.15 K. As 1,4-butanediol is added, the mole fraction of dimethyl sulfoxide decreases and the partial molar volume of dimethyl sulfoxide increases. With both partial molar volumes increasing above the partial molar volumes of the two “neat” co-solvents, the excess molar volume, VmE, must be positive. All of the numerical values of VmE values at 293.15 K in Table 6 are negative, hence there is an inconsistency in the calculated excess molar volumes and partial molar volumes of the two mixture components. For those that wish more of a mathematical discussion, the excess molar volume is defined as: V Em ¼ V m;mixture −V m;ideal solution
ð1Þ
the difference between the actual molar volume of the binary mixture, Vm,mixture, and the molar volume of the ideal solution at the given binary mixture composition, Vm,ideal solution. The molar volume of the binary mixture is equal to: V m;mixture ¼ x1 V m;1 þ x2 V m;2
ð2Þ
the mole fraction average of the partial molar volumes of the mixture components at the mixture mole fraction composition, and the molar volume of the binary ideal solution is equal to: V m;ideal solution ¼ x1 V m;1 þ x2 V m;2
ð3Þ
238
W.E. Acree Jr, F. Martínez / Journal of Molecular Liquids 272 (2018) 237–238
the mole fraction average of the molar volumes of the two “neat” liquid co-solvents, Vm, 1∗and Vm, 2∗, which in the present case are the partial molar volume of 1,4-butanediol at x1,4-butanediol = 1.0 and the partial molar volume of dimethyl sulfoxide at xdimethyl sulfoxide = 1.0. Combination of Eqns. 1–3 yields the following expression for calculating the excess molar volume: V Em ¼ x1 V m;1 −V m;1 þ x2 V m;2 −V m;2
ð4Þ
The excess molar volume at 293.15 K and at a mole fraction composition of 1,4-butanediol of x1 = 0.5145 is obtained by substituting the partial molar volumes of Vm,1 = 88.83 cm3 mol−1 and Vm,2 = 71.11 cm3 mol−1 into Eq. (4): V Em ¼ 0:5145ð88:83−88:72Þ þ 0:4855ð71:11−71:00Þ
ð5Þ
The calculated excess molar volume based on the partial molar volume data from Table 9 is positive, VmE = 0.11 cm3 mol−1. The authors calculated value from Table 6 is VmE = −0.0605 cm3 mol−1. Checking the authors' calculated volumetric properties at temperatures other than 293.15 K for thermodynamic consistency will require numerical calculations. For example, the partial molar volumes 1,4butanediol at 298,15 K decrease with increasing concentration of
dimethyl sulfoxide. The partial molar volume of dimethyl sulfoxide still increases with increasing 1,4-butanediol mole fraction. The excess molar volume at 298.15 K and at a mole fraction composition of 1,4butanediol of x1 = 0.5145 is obtained by substituting the partial molar volumes of Vm,1 = 88.91 cm3 mol−1 and Vm,2 = 71.42 cm3 mol−1 into Eq. (4): V Em ¼ 0:5145 ð88:91−89:00Þ þ 0:4855 ð71:42−71:31Þ
ð6Þ
The calculated excess molar volume based on the partial molar volume data from Table 9 is positive, VmE = 0.007 cm3 mol−1. The authors calculated value from Table 6 is VmE = −0.0589 cm3 mol−1. We suspect that there are other inconsistencies between the tabulated values in Tables 6 and 9. The errors that we found could have been avoided had the authors checked their calculated values for internal consistency using Eq. (4). References [1] X. Yue, L. Zhao, L. Ma, H. Shi, T. Yang, J. Zhang, Density, dynamic viscosity, excess property and intermolecular interplay studies for 1,4-butanediol + dimethyl sulfoxide binary mixture, J. Mol. Liq. 263 (2018) 40–48.