Excess molar volume

Figure 7.5 Comparison of excess molar volumes for four mixtures as follows Curve 1 . y,C 0H22 +. y2c-C6H,2 at 7=313.15 K.

In this equation E (R2) is the excess molar refraction, S (tt ) is the solute dipolarity-polarizabiUty, A (2a ) and B(2 3 ) are the solute H-bond acidity and basicity, respectively, and Vis the McGowan characteristic volume (in cm mol /100). The solute size, V, (molecule favors octanol) together with solute H-bond basicity, B, (favors water) are the dominating parameters of this equation. The use of Bo(2P ) resulted in equation... 

In an excellent paper, Zhao et al. [29] assembled a carefully reviewed literature set of human absorption data on 241 drugs. They showed that a linear regression model built with 5 Abraham descriptors could fit percent human absorption data reasonably well (r2 = 0.83, RMSE = 14%). The descriptors are excess molar refraction (E), polarizability (S), hydrogen bond acidity (A), hydrogen bond basicity (B), and McGowan volume (V), all related to lipophilicity, hydrophilicity, and size. In a follow-on paper, data on rat absorption for 151 drugs was collected from the literature and modeled using the Abraham descriptors [30]. A model with only descriptors A and B had r2 = 0.66, RMSE = 15%. 

Abraham et at. [2], [3], [4] Solubility, excess molar refraction, polarizability, hydrogen-bond acidity/basicity, and McGowan volume... 

AV is then the excess molar volume of products over that of reactants, in their standard states. For dilute solutions, where activity corrections may be neglected, and where Kx is expressed in mole fraction units... 

CALCULATION OF PARTIAL MOLAR QUANTITIES AND EXCESS MOLAR QUANTITIES FROM EXPERIMENTAL DATA VOLUME AND ENTHALPY... 

In this chapter, we shall consider the methods by which values of partial molar quantities and excess molar quantities can be obtained from experimental data. Most of the methods are applicable to any thermodynamic property J, but special emphasis will be placed on the partial molar volume and the partial molar enthalpy, which are needed to determine the pressure and temperature coefficients of the chemical potential, and on the excess molar volume and the excess molar enthalpy, which are needed to determine the pressure and temperature coefficients of the excess Gibbs function. Furthermore, the volume is tangible and easy to visualize hence, it serves well in an initial exposition of partial molar quantities and excess molar quantities. 

Chandrasekhar, G., Venkatesu, P., and Rao, M.V.P. Excess molar volumes and speed of sound of ethyl acetate and butyl acetate with 2-alkoxyethanols at 308.15 K, J. Chem. Eng. Data, 45(4) 590-593, 2000. 

Comelli, F. and Francesconi, R. Isothermal vapor-liquid equilibria measurements, excess molar enthalpies, and excess molar volumes of dimethyl carbonate + methanol. + ethanol, and propan-l -ol at 313.15 K. J. Chem. Eng. Data, 42(4) 705-709, 1997. 

Lu, H., Wang, J., Zhao, Y., Xuan, X., and Zhuo, K. Excess molar volumes and viscosities for binary rtrixtrrres of y-butyrolactone with methyl formate, ethyl formate, methyl acetate, ethyl acetate, and acetonitrile at 298.15 K,J. Chem. Eng. Data, 46(3) 631-634, 2001. 

Resa, J.M., Gonzalez, C., de Eandaluce, S.O., and Eanz, J. Densities, excess molar volumes, and refractive indices of ethyl acetate and aromatic hydrocarbon binary mixtures. J. Chem. Thermodyn, 34(7) 995-1004. 2002. 

Sastry, N.V., George, A., Jain, N.J., and Bahadur, P. Densities, relative permittivities, excess volumes, and excess molar polarizations for alkyl ester (methyl propanoate, methyl butanoate, ethyl propanoate, and ethyl butanoate) + hydrocarbons (n-heptane, benzene, chlorobenzene, and 1,1,2,2-tetrachloroethane) at 308.15 and 318.15 K, J. Chem. Eng. Data, 44(3) 456-464, 1999. 

Tanaka. R. and Toyama, S. Excess molar volumes and excess molar heat capacities for binary mixtures of ethanol with chlorocyclohexane, 1-nitropropane, dibutyl ether, and ethyl acetate at the temperature of 298.15 K. 7 Chem. Eng. Data, 41(6) 1455-1458,1996. 

Zhao and coworkers [53] also constructed a linear model using the Abraham descriptors. The MLR model possesses good correlation and predictability for external data sets. In this equation, E is an excess molar refraction (cm3/mol/ 10.0) and S the dipolarity/polarizability, A and B are the hydrogen bond acidity and basicity, respectively, and V is the McGowan characteristic volume (cm3/ mol/100). The large coefficients of A and B indicate too polar molecules having poor absorption. 

Less negative values of the excess molar volumes were obtained for the IL with the longer alkyl chain in the cation for the same alcohol. The structure of [C4CiIm][CiS04] is less H-bonded than [CiCiIm][CiSOJ in the pure state. 

The excess molar volumes for [C0CiIm][BF4] + 1-butanol, or 1-pentanol were found very small and negative in the alcohol-rich range of the mixture composition and positive in the alcohol-poor range [62]. More positive values were observed for 1-pentanol ( (max) = 0-92 cm moD at equimolar composition and 298.15 K). 

The influence of temperature and pressure on the excess molar volume is not very well known. For ILs the values were observed more negative at higher temperature [60,63]. Increasing the pressure from 0.1 to 20 MPa at the same temperature, less negative values of were observed [63]. The influence of temperature on the values at the pressure 15 MPa for [CiCiIm][CiS04] -t methanol is presented in Figure 1.4. 

Strong intermolecular interactions between the hydroxyl group and the IL lead to the negative values of excess molar volumes,, and excess molar enthalpies The strongly negative curve for [CiQlm][QS04] + water, ... 

Zafarani-Moattar, M.T. and Shekaari, H. Volumetric and speed of sound of ionic liquid, l-butyl-3-methylimidazolium hexafluorophosphate with acetonitrile and methanol at T = (298.15 to 318.15) K, /. Chem., Eng. Data, 50,1694,2005. Wang, J. et al.. Excess molar volumes and excess logarithm viscosities for binary mixtures of the ionic liquid l-butyl-3-methylimidazolium hexafluorophosphate with some organic solvents, /. Solution Chem., 34, 585, 2005. 

Heintz, A. et al.. Excess molar volumes and liquid-liquid equilibria of the ionic liquid l-methyl-3-octyl-imidazolium tetrafluoroborate mixed with butan-l-ol and pentan-l-ol, /. Solution Chem., 34,1135, 2005. 

Here E is the solute excess molar refractivity, S is the solute dipolarity/ polarizability A and B are the overall or summation hydrogen-bond acidity and basicity, respectively and V is the McGowan characteristic volume lower-case letters stand for respective coefficients which are characteristic of the solvent, c is the constant. By help of sfafisfical methods like the principal component analysis and nonlinear mapping, the authors determined the mathematical distance (i.e., measure of dissimilarify) from an IL fo seven conventional solvents immiscible with water. It appears that the closest to the IL conventional solvent is 1-octanol. Even more close to IL is an aqueous biphasic system based on PEG-200 and ammonium sulfate (and even closer are ethylene glycol and trifluoroethanol, as calculated for hypofhefical water-solvenf sysfems involving fhese solvenfs). 

The excess molar volumes of 10-40 mol % methanol/C02 mixtures at 26°C as a function of pressure has been determined. The excess molar volumes varied with composition and pressure significant interaction between CO2 and methanol was noted from the observed excess molar volumes. To better characterize the interaction and its effect on analyte solubility, the partial molar volume of naphthalene at infinite dilution in liquid 10 and 40 mol % methanol/C02 mixtures was determined. The variation of the partial molar volume at infinite dilution with pressure correlated well with isothermal compressibility of the methanol/C02 mixtures (Souvignet and Olesik, 1995). 

Tzou TZ. Density, excess molar volume, and vapor pressure of propellant mixtures in metered-dose inhalers deviation from ideal mixtures. Respir Drug Delivery YI, Int Symp 1998 439-443. 

Figure 17.4 Excess molar volumes at T= 298.15 K and p = 0.1 MPa for (a) (xiCmH2m + 2+ 2C-C6H 2) and (b) (xiCmH2m + 2 + x2n-C6Hi4). The numbers on the graph give m, the number of carbon atoms in the n-alkane.

Figure 17.5 Derived thermodynamic properties at T — 298.15 K and p = 0.1 MPa for (2Cic-CfiHi2 + X2n-CjHi4) (a) excess molar heat capacities obtained from the excess molar enthalpies (b) relative partial molar heat capacities obtained from the excess molar heat capacities (c) change of the excess molar volume with temperature obtained from the excess molar volumes and (d) change of the excess molar enthalpies with pressure obtained from the excess molar volumes.

Figure 17.6 Excess molar properties at p = 0.1 MPa for (X111-C7H16 +X2I-C4H9CI) (a) gives the excess molar enthalpies. The solid line represents values at T= 298.15 K, while the dashed line gives values changed to T = 323.15 K, using the excess molar heat capacities at T = 298.15 K shown in (b). The excess molar volumes at T= 298.15 K are shown in (c).

---