The Effect of Pressure and Temperature on the Second-Order Derivatives of the Free Energy Functions for Lower Alkanediols

Abstract

The second-order derivatives of the free energy functions, i.e., isochoric molar heat capacities, isentropic and isothermal molar compressibility, and isobaric and isentropic molar thermal expansion, were calculated in the temperature range from (293.15 to 318.15) K and at pressures up to 100 MPa for 1,2-and 1,3-propanediol; 1,2-, 1,3, and 1,4-butanediol; and 2-methyl-2,4-pentanediol. The data for calculations were obtained by means of the acoustic method. The pressure and temperature dependencies for the above mentioned properties are analyzed and discussed together with the literature data on isobaric molar heat capacities. The observed marked difference between isobaric and isentropic thermal expansion is analyzed as well. The differences in behavior of linear 1,2-diols and α, ω-diols as well as a diol with a branched carbon chain are emphasized. The isentropic and isothermal molar compressibilities are used to evaluate the dimensionality and relative rigidity of H-associates.

Acoustic Nonlinearity Parameter B/A, Internal Pressure, and Acoustic Impedance Determined at Pressures up to 100 MPa for 1-Ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide

“…It is in accordance with previous results for akanediols (Zorębski, Zorębski, 2014) and other reports which show to be sure very slightly temperature dependence but in the broader temperature range (Beyer, 1960;Khelladi et al, 2009). Also the contribution to B/A from temperature changes is much smaller than that due to pressure changes.…”

“…Needed for calculations but not reported previously the values of α p (p, T ) and c p (p, T ) are calculated by means of the acoustic method similarly as in our previous works (Zorębski, Dzida, 2012;Dzida, 2004;Zorębski, 2014). Generally, this method is based on Table 1.…”

“…This route is based on well-known Newton-Laplace relation which connected speed of sound with density and isentropic compressibility coefficient. Especially at high pressures, the reliability, relative low uncertainty and simplicity of the speed of sound measurements make it very attractive for indirect determination of the excellent quality data on related (to speed of sound) thermodynamic and thermophysic properties which would have been difficult to obtain otherwise (Takagi, Wilhelm, 2010;Goodwin, Trusler, 2003;Dzida, 2004;Zorębski, 2014). For example, in this way extremely rare reported values of internal pressure and B/A nonlinearity parameter can be obtained (López et al, 2006;Zorębski, Zorębski, 2014).…”

Isobaric and Isochoric Heat Capacities as Well as Isentropic and Isothermal Compressibilities of Di- and Trisubstituted Imidazolium-Based Ionic Liquids as a Function of Temperature

“…Although isobaric and isochoric heat capacities are among the most important thermophysical properties of matter, papers reported simultaneously both heat capacities are very limited. − Both quantities are measurable state functions, but while the values of the isobaric heat capacities of liquids can be obtained with relative ease by direct calorimetric determination, the rather scarce values of isochoric heat capacities are mostly obtained indirectly by the use of an acoustic method. There is a very attractive route taking into account difficulties that exist during calorimetric determination of isochoric heat capacities of liquids in standard conditions. , Using this route, we have reported very recently isochoric heat capacities for 11 aprotic imidazolium- and pyrrolidinium-based ionic liquids (ILs) together with their thermophysical material constants and isobaric heat capacities …”

Isobaric and Isochoric Heat Capacities of Imidazolium-Based and Pyrrolidinium-Based Ionic Liquids as a Function of Temperature: Modeling of Isobaric Heat Capacity

“…Although heat capacities (both isobaric and isochoric) belong to the very important thermophysical properties of matter and their ratio gives the equally important adiabatic index, reports about both heat capacities are rather limited. − Both heat capacities are measurable state functions, but while the isobaric heat capacity is the quantity of interest mainly from a practical point of view, the isochoric heat capacity is the quantity needed in more theoretically oriented works (isochoric values are indispensable for the better understanding of processes on the molecular level). Moreover, while the reported values of the isobaric heat capacities of liquids are obtained by direct calorimetric determination, the relatively scarce values of isochoric heat capacities are for the most part obtained indirectly by the use of the acoustic method.…”