The Journal of Chemical Thermodynamics (v.39, #1)

Guide for Authors (iii-vii).

Calorimetry gives insight into the stability of nanophase materials. Using TiO2 as an example, the interplay of energetics of polymorphism, surface energy, and surface hydration is discussed. Oxide melt solution calorimetry, water adsorption calorimetry, and adiabatic heat capacity studies together show the following. The metastability of bulk polymorphs increases in the order rutile, brookite, anatase, while the surface energy increases in the opposite order. This leads to crossovers in phase stability at the nanoscale, which appears to be a general phenomenon. Hydration plays a major role in stabilizing nanoparticles and the first layers of water are tightly bound. There is little excess heat capacity and no significant excess vibrational entropy in nanophase rutile or anatase. Further applications of calorimetry to thin films, interfaces, multilayers, and sub-milligram samples are presented.
Keywords: Calorimetry; Titania polymorphs; Nanoparticles; Surface energy; Hydration;

Vapour pressures and enthalpies of vaporization of a series of δ-lactones by Vladimir N. Emel’yanenko; Svetlana A. Kozlova; Sergey P. Verevkin; Gennady N. Roganov (10-15).
Vapour pressures and molar enthalpies of vaporization of a series of δ-lactones (δ-valerolactone (CAS#542-28-9), δ-hexanolactone (CAS#823-22-3), δ-octanolactone (CAS#698-76-0), δ-nonanolactone (CAS#3301-94-8), and δ-decanolactone (CAS#705-86-2)) have been determined by the transpiration method. A linear correlation of enthalpies of vaporization Δ l g H m at T  = 298.15 K of the δ-lactones studied with the number of carbon atoms has been found.
Keywords: δ-Lactones; Transpiration method; Vapour pressure; Enthalpy of vaporization;

The values of density and viscosity of the binary liquid mixtures of N-methylacetamide with some chloroethanes (1,2-dichloroethane, 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane) and chloroethenes (trichloroethene and tetrachloroethene) are measured over the entire range of composition at T  = 308.15 K. These values have been used to calculate the excess molar volumes (V E) and deviations in viscosity (Δη). The excess molar volumes and deviations in viscosity are fitted to a Redlich–Kister type equation. Other parameters like excess Gibbs free energy of activation of viscous flow ( G ∗ E ) and Grunberg–Nissan interaction constant (d′) are also utilized in the qualitative analysis to elicit the specific interactions like complex formation as well as the saturation of chlorine atoms with π-electrons.
Keywords: Binary mixtures; N-methylacetamide; Chloroethanes; Chloroethenes; Deviations;

The standard Gibbs free energy of formation of Na2ZrO3 has been re-determined by a solid state electrochemical approach that allows the measurement to be performed without any distortion by electronic transference through the galvanic cell, thus avoiding a possible error of previous electrochemical investigations. The method is based on the determination of the oxygen chemical potential that, via the sodium oxide activity of an auxiliary phase, is reproducibly related to the sodium chemical potential established by the heterogeneous phase equilibrium Na2ZrO3(s)/ZrO2(s)/O2. The standard Gibbs free energy of formation of Na2ZrO3 yields (450 °C to 650 °C): Δ f G Na 2 ZrO 3 ∘ [ kJ/mol ] = - 1711.828 ± 53.21 + ( 310.974 ± 66.52 ) · 10 - 3 · T / K. This data is by about 55 kJ/mol more negative than the findings of previous electrochemical studies, thus proving the significance of electronic transference therein.
Keywords: Gibbs free energy of formation; Sodium zirconate; Solid state potentiometry; Electronic transference; Na-beta-alumina;

Densities and viscosities for binary mixtures of N-methyl-2-pyrrolidinone with cyclohexane, benzene, and toluene were determined at different temperatures and atmospheric pressure. The measurements were carried out over the whole range of composition, using a vibrating-tube density meter and Ubbelohde viscometer. Density, viscosity were used to compute the excess mole volumes, V E, viscosity deviations, Δη and the excess energies of activation, ΔG ∗E. Results have been fitted to Redlich–Kister equation to derive the coefficients and estimate the standard error values. A discussion on these quantities in terms of molecular interactions is reported. The experimental data of molar volumes are regressed by the Peng–Robinson equation with different alpha function. The mean root mean square deviations between experimental and calculated values for different binary mixtures are no more than 3.5%.
Keywords: Density; Viscosity; N-Methyl-2-pyrrolidinone;

Standard molar enthalpies of formation of the acetylpyridine isomers by Vera L.S. Freitas; Liliana I.P. Oliveira; Maria D.M.C. Ribeiro da Silva (39-43).
The present work reports the values of the gaseous standard (p  = 0.1 MPa) molar enthalpies of formation of the three acetylpyridine isomers, at T  = 298.15 K. For each isomer, that value was derived from measurements of the standard molar energy of combustion of the corresponding liquid, using a static bomb calorimeter, together with measurements of the standard molar enthalpy of vaporization, measured by Calvet microcalorimetry. Compound Δ c H m ∘ ( l ) / kJ · mol - 1 Δ l g H m ∘ ( T = 298.15 K ) / kJ · mol - 1 2-Acetylpyridine −3653.2 ± 2.7 60.5 ± 0.3 3-Acetylpyridine −3653.7 ± 2.5 66.1 ± 0.8 4-Acetylpyridine −3652.3 ± 1.6 66.5 ± 0.9
Keywords: Acetylpyridine isomers; Pyridine derivatives; Combustion calorimetry; Enthalpy of vaporization; Enthalpy of formation;

Determination of thermodynamic properties of Na2S using solid-state EMF measurements by Gustav Lindberg; Anders Larsson; Mathias Råberg; Dan Boström; Rainer Backman; Anders Nordin (44-48).
To obtain reliable thermodynamic data for Na2S(s), solid-state EMF measurements of the cell Pd(s)|O2(g)|Na2S(s), Na2SO4(s)|YSZ| Fe(s), FeO(s)|O2(g)ref| Pd(s) were carried out in the temperature range 870 <  T/K < 1000 with yttria stabilized zirconia as the solid electrolyte. The measured EMF values were fitted according to the equation E fit/V (±0.00047) = 0.63650 − 0.00584732(T/K) + 0.00073190(T/K) ln (T/K). From the experimental results and the available literature data on Na2SO4(s), the equilibrium constant of formation for Na2S(s) was determined to be lg  K f(Na2S(s)) (±0.05) = 216.28 − 4750(T/K)−1  − 28.28878 ln (T/K). Gibbs energy of formation for Na2S(s) was obtained as Δf G (Na2S(s))/(kJ · mol−1) (±1.0) = 90.9 − 4.1407(T/K) + 0.5415849(T/K) ln (T/K). By applying third law analysis of the experimental data, the standard enthalpy of formation of Na2S(s) was evaluated to be Δf H (Na2S(s), 298.15 K)/(kJ · mol−1) (±1.0) = −369.0. Using the literature data for C p and the calculated Δf H , the standard entropy was evaluated to S (Na2S(s), 298.15 K)/(J · mol−1  · K−1) (±2.0) = 97.0.
Keywords: Sodium sulfide; EMF; Thermochemical data;

By measuring the (vapour + liquid) equilibrium of {methanol (1) + benzene (2) + NaI} and testing the data using the ternary Gibbs–Duhem equation, the experimental results of the (vapour + liquid) equilibrium with thermodynamic consistency are obtained. It is supposed that the mean activity coefficients of NaI in (methanol + benzene) mixed solvents may be represented by a power series of salt concentration (m 1/2). Each parameter of the series was then obtained from the experimental results by the method of least squares. The calculated results show that the activity coefficients of NaI in (methanol + benzene) system with constant composition either decrease as the concentration increases, or decrease at first, then pass through a minimum and increase gradually again. This method is applicable to the determination of electrolytic activity coefficients in mixed non-aqueous solvents.
Keywords: Mixed non-aqueous solvents; (Vapour + liquid) equilibrium; Activity coefficients; Sodium iodide;

Densities of the binary liquid mixtures of (2-methoxyethanol + 1-propanol, or 2-propanol, or 1,2-propandiol) have been measured over the entire range of compositions at temperatures from (293.15 to 343.15) K and ambient pressure 81.5 kPa, using a vibrating-tube densimeter. The excess molar volumes V m E , thermal expansion coefficients α, and their excess values α E, and isothermal coefficient of pressure excess molar enthalpy ∂ H m E / ∂ P T , x , were calculated from experimental densities. The excess molar volume is positive for (2-methoxyethanol + 1-propanol) and becomes more positive with increasing temperature. The excess molar volume for (2-methoxyethanol + 2-propanol) shows a S-shaped dependence on composition with positive values in the 2-propanol rich-region and negative values at the opposite extreme. With increasing temperature from (293.15 to 313.15) K, it increases but beyond this range with increasing temperature from (313.15 to 343.15) K it decreases. The excess molar volume is negative for (2-methoxyethanol + 1,2-propandiol) and becomes more negative with increasing temperature. The excess molar volumes were correlated with a Redlich–Kister type equation.
Keywords: Densities; Excess molar volume; 2-Methoxyethanol; Thermal expansion coefficient; Alkanol;

We have measured the densities of aqueous solutions of isoleucine, threonine, and equimolal solutions of these two amino acids with HCl and with NaOH at temperatures 278.15 ⩽  T/K ⩽ 368.15, at molalities 0.01 ⩽  m/mol · kg−1  ⩽ 1.0, and at the pressure 0.35 MPa using a vibrating tube densimeter. We have also measured the heat capacities of these solutions at 278.15 ⩽  T/K ⩽ 393.15 and at the same m and p using a twin fixed-cell differential temperature-scanning calorimeter. We used the densities to calculate apparent molar volumes V ϕ and the heat capacities to calculate apparent molar heat capacities C p,ϕ for these solutions. We used our results and values from the literature for V ϕ (T,  m) and C p,ϕ (T,  m) for HCl(aq), NaOH(aq), and NaCl(aq) and the molar heat capacity change Δr C p,m(T,  m) for ionization of water to calculate parameters for Δr C p,m(T,  m) for the two proton dissociations from each of the protonated aqueous cationic amino acids. We used Young’s Rule and integrated these results iteratively to account for the effects of equilibrium speciation and chemical relaxation on V ϕ (T,  m) and C p,ϕ (T,  m). This procedure gave parameters for V ϕ (T,  m) and C p,ϕ (T,  m) for threoninium and isoleucinium chloride and for sodium threoninate and isoleucinate which modeled our observed results within experimental uncertainties. We report values for Δr C p,m, Δr H m, pQ a, Δr S m, and Δr V m for the first and second proton dissociations from protonated aqueous threonine and isoleucine as functions of T and m.
Keywords: Apparent molar volume; Apparent molar heat capacity; Threonine; 2-Amino-3-hydroxybutanoic acid; Isoleucine; 2-Amino-3-methylpentanoic acid; Zwitterion; Threoninium chloride; Isoleucininium chloride; Sodium threoninate; Sodium isoleucinate; Proton dissociations; Acidity; Young’s Rule;

Densities and volumes of mixing of the ternary system toluene + butyl acrylate + methyl methacrylate and its binaries at 298.15 K by Jaime Wisniak; Isabel Villarreal; René D. Peralta; Ramiro Infante; Gladis Cortez; Homero Soto (88-95).
Densities of the ternary system toluene + butyl acrylate + methyl methacrylate and its three binaries have been measured in the whole composition range, at 298.15 K and atmospheric pressure using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess molar volumes are positive for the binary systems toluene + methyl methacrylate and butyl acrylate + methyl methacrylate and negative for the system toluene + butyl acrylate. The corresponding data were correlated with the Redlich–Kister equation and with a series of Legendre polynomials. Several empirical equations were used to correlate the ternary behavior from the excess molar volume data of their constituent binaries and were found equally good to fit the data. The best fit was based on a direct approach, without information on the component binary systems.
Keywords: Densities; Excess molar volumes; Toluene; Acrylates; Ternary systems;

The water activities of aqueous electrolyte mixture (NaCl + KCl + LiCl + H2O) were experimentally determined at T  = 298.15 K by the hygrometric method at total ionic-strength from 0.4 mol · kg−1 to 6 mol · kg−1 for different ionic-strength fractions y of NaCl with y  = 1/3, 1/2, and 2/3. The data allow the deduction of new osmotic coefficients. The results obtained were correlated by Pitzer’s model and Dinane’s mixing rules ECA I and ECA II for calculations of the water activity in mixed aqueous electrolytes. A new Dinane–Pitzer model is proposed for the calculation of osmotic coefficients in quaternary aqueous mixtures using the newly ternary and quaternary ionic mixing parameters of this studied system. The solute activity coefficients of component in the mixture are also determined for different ionic-strength fractions y of NaCl.
Keywords: Aqueous mixed-electrolyte; Sodium–potassium–lithium chloride solutions; Relative humidity; Water activity; Osmotic coefficient; Activity coefficient; Pitzer’s model; ECA rule;

The heat capacity of BaUO4 by K. Popa; E. Colineau; F. Wastin; R.J.M. Konings (104-107).
The heat capacity of barium uranate BaUO4 has been measured in the temperature range (1.9 to 1570) K in order to resolve the discrepancy between two existing low-temperature calorimetric studies on this compound. Our results are in good agreement with one of the two earlier studies, and the impact of this finding is discussed.
Keywords: Heat capacity; Entropy; Enthalpy increment; Calorimetry; Barium uranate;

The standard molar enthalpy of formation, molar heat capacities, and thermal stability of anhydrous caffeine by Jia-Xin Dong; Qiang Li; Zhi-Cheng Tan; Zhi-Heng Zhang; Yi Liu (108-114).
The constant-volume energy of combustion of crystalline anhydrous caffeine (C8H10N4O2) in α (lower temperature steady) crystal form was measured by a bomb combustion calorimeter, the standard molar enthalpy of combustion of caffeine at T  = 298.15 K was determined to be −(4255.08 ± 4.30) kJ · mol−1, and the standard molar enthalpy of formation was derived as −(322.15 ± 4.80) kJ · mol−1. The heat capacity of caffeine in the same crystal form was measured in the temperature range from (80 to 387) K by an adiabatic calorimeter. No phase transition or thermal anomaly was observed in the above temperature range. The thermal behavior of the compound was further examined by thermogravimetry (TG), differential thermal analysis (DTA) over the range from (300 to 700) K and by differential scanning calorimetry (DSC) over the range from (300 to 540) K, respectively. From the above thermal analysis a (solid–solid) and a (solid–liquid) phase transition of the compound were found at T  = (413.39 and 509.00) K, respectively; and the corresponding molar enthalpies of these transitions were determined to be (3.43 ± 0.02) kJ · mol−1for the (solid–solid) transition, and (19.86 ± 0.03) kJ · mol−1 for the (solid–liquid) transition, respectively.
Keywords: Caffeine; Standard molar enthalpy of formation; Heat capacity; Phase transition;

Densities of binary mixtures formed by benzene, or toluene, or ethylbenzene with N-methyl-2-pyrrolidone have been measured over the full range of compositions at atmospheric pressure and various temperatures by means of a vibrating-tube densimeter. The excess molar volume V m E calculated from the density data provide the temperature dependence of V m E in the temperature range of (293.15 to 353.15) K. The V m E results were correlated using the fourth-order Redlich–Kister polynomial equation, with the maximum likelihood principle being applied for the determination of the adjustable parameters. Partial molar volumes of two components were also calculated. It was found that the V m E in the systems studied decrease with rising temperature.
Keywords: N-methyl-2-pyrrolidone; Benzene; Toluene; Ethylbenzene; Binary mixture; Excess volume; Partial molar volume; Temperature dependence;

(Liquid + liquid) equilibrium (LLE) data for (water + propionic acid + dipropyl ether) and (water + propionic acid + diisopropyl ether) were measured at T  = 298.2 K and atmospheric pressure. The tie-line data were correlated by means of the UNIQUAC equation, and compared with results predicted by the UNIFAC method. A comparison of the extracting capabilities of the solvents was made with respect to distribution coefficients, separation factors, and solvent free selectivity bases.
Keywords: LLE; Propionic acid; UNIQUAC; UNIFAC;

Excess molar enthalpies H m E and excess molar volumes V m E have been determined experimentally at atmospheric pressure and at a temperature of 298.15 K, for a set of 25 binary mixtures composed of the first five methyl esters (methanoate to pentanoate) with five 1,ω-dibromoalkanes (1,2-dibromoethane to 1,6-dibromohexane). Most of the mixtures present positive net mixing effects, endothermic with dilatation, with the exception of those that contain butanoates and pentanoates with the shorter α,ω-dibromoalkanes, which present negative H m E values and, by contrast, negative V m E values when ω  ⩾ 5, but in both cases at high methyl ester compositions. The experimental data are correlated with a suitable polynomial equation, used previously by our group.Two known versions of the UNIFAC group contribution model are used, the original version by Dang and Tassios and the more recent version of Gmehling et al. The estimations are unacceptable in both cases, so the parameters corresponding to carboxylate/bromine interaction are recalculated for the former version, differentiating the interaction type according to ester acid chain. There is a marked improvement for the methanoate and ethanoate mixtures, although the estimations are not acceptable for the other esters. The second version of UNIFAC, by Gmehling et al., requires other data not available in the literature.
Keywords: Excess volume; Excess enthalpy; Dibromoalkane; Ester; UNIFAC;

The thermodynamics of vaporization of ethyl tert-butyl ether, isobutyl tert-butyl ether, and di-isopropyl ether by A.A. Efimova; L.L. Pashchenko; R.M. Varushchenko; E. Krasnyh; S.V. Levanova (142-147).
The boiling temperatures of ethyl tert-butyl ether (ETBE), isobutyl tert-butyl ether (IBTBE), and di-isopropyl ether (DIPE) have been measured by comparative ebulliometry over the moderate pressure range 10.8 ⩽ (P/kPa) ⩽ 101.7. The equations of the temperature dependences of the saturated vapour pressures and enthalpies of vaporization have been derived. The normal boiling temperatures of the ethers were computed to be 345.84 K, 386.06 K, and 341.64 K, respectively. The experimental data on the vapour pressure of the ethers under study were extended to the whole range of the liquid phases between critical and triple points by means of corresponding states law and combined treatment of the pT-parameters and low-temperature differences of the heat capacities of ideal gas and liquid, Δ C p = C p ∘ ( g ) - C p ∘ ( l ) , respectively.
Keywords: Comparative ebulliometry; Saturation vapour pressure; Enthalpy of vaporization; Critical parameters; Ether;

Volumetric and refractive properties of binary mixtures containing 1,4-dioxane and chloroalkanes by B. Giner; C. Lafuente; A. Villares; M. Haro; M.C. López (148-157).
Refractive index deviations, excess volumes, and molar refractions of binary mixtures containing 1,4-dioxane and 1-chloropropane or isomeric chlorobutanes have been calculated from experimental data of refractive indices and densities at temperatures of 298.15 K and 313.15 K. Results obtained have been discussed in terms of intermolecular interactions and a comprehensive discussion has been provided. Excess volumes have been also correlated using Peng–Robinson–Stryjek–Vera cubic equation of state and the relation between parameter b (covolume) from the equation of state and molar refraction has been verified. Refractive indices were compared with those predicted using the equation of state and several mixing rules.
Keywords: Refractive index; Excess volume; 1,4-Dioxane; Chloroalkane; Equation of state;

Thermodynamic properties of 1-alkyl-3-methylimidazolium bromide ionic liquids by Y.U. Paulechka; G.J. Kabo; A.V. Blokhin; A.S. Shaplov; E.I. Lozinskaya; Ya.S. Vygodskii (158-166).
Heat capacities and enthalpies of phase transitions for a series of 1-alkyl-3-methylimidazolium bromide ionic liquids have been measured by adiabatic calorimetry. Thermodynamic properties of the compounds were calculated in the temperature range of (5 to 370) K. Water was found to have an additive contribution to the heat capacities of [C4mim]Br in the liquid state above T fus and in the solid state below 160 K at w(H2O) ⩽ 5 · 10−3.
Keywords: Ionic liquids; Thermodynamic properties; 1-Alkyl-3-methylimidazolium bromides; Synthesis of high-purity ionic liquids;

Corrigendum to “Thermochemistry of alkaline-earth phenoxides” [J. Chem. Thermodyn. 38 (2006) 296–303] by Carla Hipólito; João Paulo Leal; Yanzhi Guo; Matthias Epple (167-168).