J. Bevan Ott

Chemical Thermodynamics: Principles and Applications

Preface to the Two-Volume Series. Preface to the First Volume. Introduction. The First and Second Laws of Thermodynamics. Thermodynamic Relationships and Applications. The Third Law and Absolute Entropy Measurements. The Chemical Potential and Equilibrium. Fugacity, Activity, and Standard States. The Thermodynamic Properties of Solutions. The Equilibrium Condition Applied to Phase Equilibria. The Equilibrium Condition Applied to Chemical Processes. Statistical Thermodynamics. APPENDIX 1: Mathematics for Thermodynamics. APPENDIX 2: The International Temperature Scale of 1990. APPENDIX 3: Equations of States for Gases. APPENDIX 4: Calculations from Statistical Thermodynamics.

(Solid + liquid) phase equilibria and solid-hydrate formation in water + methyl, + ethyl, + isopropyl, and + tertiary butyl alcohols

Abstract (Solid + liquid) phase diagrams have been obtained from time-temperature melting curves for water + methyl, + ethyl, + isopropyl, and + tertiary butyl alcohols. Incongruently melting hydrates form in all four systems. In addition, water + t-butyl alcohol has a congruently melting compound. Correlations between inflexions found in the water-rich compositions of the (solid + liquid) equilibrium lines and the size of the alkyl groups of the alcohols are noted, and a possible interpretation is given.

Excess volumes of cyclohexane + n-hexane, + n-heptane, + n-octane, + n-nonane, and + n-decane

Abstract Excess volumes have been obtained with the vibrating tube densimeter for cyclohexane + n -hexane, + n -heptane, + n -octane, + n -nonane, and + n -decane at the three temperatures 283.15, 298.15, and 313.15 K. The excess volume increases regularly with increasing size of the alkyl group of the hydrocarbon.

Excess volumes, enthalpies, and Gibbs free energies for mixtures of benzene + p-xylene

Excess thermodynamic properties of benzene + p-xylene have been obtained at 288.15, 298.15, and 313.15 K. VE was obtained with a Sodev vibrating-tube densimeter, HE with a Picker flow microcalorimeter, and GE was calculated from solid + liquid phase equilibria measurements. Measurements were also made of the heat capacity of liquid p-xylene as a function of temperature using the heat-capacity unit of the Picker flow microcalorimeter.

(Solid + liquid) phase equilibria in binary mixtures containing benzene, a cycloalkane, an n-alkane, or tetrachloromethane An equation for representing (solid + liquid) phase equilibria

Abstract Complete (solid + liquid) phase diagrams are reported for the 10 mixtures: {(1−x)c-CmH2m + xC6H6}, m = 6, 7, 8; {(1−x)CmH2m+2 + xC6H6}, m = 8, 11, 12; {(1−x)CmH2m+2 + xc-C6H12}, m = 8, 12; and {(1−x)CmH2m+2 + xCCl4}, m = 8, 12. All are simple eutectic systems except for {(1−x)C8H18 + xCCl4}, which has a solid-phase transition present on the CCl4 side of the diagram. The semi-empirical equation: X E =x(1−x) ∑ J=0 n a j (1−2x) J is proposed for summarizing the curves of melting temperature T against mole fraction x, where T ∗ is the melting temperature of the pure substance and x ∗ is the value of x at T ∗ . The coefficients aJ are fitted by the method of least squares. The equation very successfully describes the above systems. It also works very well for more complicated systems including those containing congruently melting or incongruently melting solid addition compounds.

Solid-liquid phase equilibria in water + ethylene glycol

Thermal methods were used to determine with high precision the solid-liquid phase equilibria diagram for water + ethylene glycol. A stable 1−1 solid hydrate forms. Because of supercooling, the hydrate is difficult to obtain; a cooling procedure was devised to initiate its crystallization. The two eutectics are at (224.12 ± 0.05) and (230.22 ± 0.05) K and mole fractions 0.288 and 0.541 of ethylene glycol, respectively. We also obtained a metastable phase diagram with a single metastable eutectic at (209.5 ± 0.5) K and mole fraction 0.335 of ethylene glycol.

Solid + liquid phase equilibria and solid compound formation in hexafluorobenzene + benzene, + pyridine, + furan, and + thiophen

Solid + liquid phase diagrams have been obtained from cooling and warming curves for the four binary systems formed from hexafluorobenzene (C 6 F 6 ) + benzene (C 6 H 6 ), + pyridine (C 5 H 5 N), + furan (C 4 H 4 O), and + thiophen (C 4 H 4 S). A stable 1—1 addition compound forms in each system. The C 6 F 6 · C 6 H 6 and C 6 F 6 · C 4 H 4 S compounds melt congruently while the C 6 F 6 · C 5 H 5 N and C 6 F 6 · C 4 H 4 O compounds melt incongruently. The relative stability of the compounds is as expected if bonding results from charge transfer with the C 6 F 6 acting as an electron acceptor and the other component as an electron donor.

Enthalpies of formation of the p-xylene + carbon tetrachloride and the benzene + hexafluorobenzene solid addition compounds

Abstract A Perkin Elmer DSC-2 differential scanning calorimeter was used to measure the enthalpies of fusion of benzene, hexafluorobenzene, p -xylene, carbon tetrachloride, and the solid addition compounds which form between p -xylene + carbon tetrachloride and benzene + hexafluorobenzene. The enthalpies of fusion are corrected to 291.15 K and combined with liquid-phase enthalpies of mixing to calculate the enthalpies of formation of the two solid addition compounds from the solid molecular components. The results are −(10.09±0.20) kJ mol −1 and −(0.08±0.20) kJ mol −1 , for p -xylene + carbon tetrachloride and benzene + hexafluorobenzene, respectively. These results support the conclusions drawn indirectly from the study of phase equilibria that the CCl 4 addition compounds with aromatic hydrocarbons are considerably more stable than the analogous C 6 F 6 compounds.

Excess enthalpies, excess volumes, and excess Gibbs free energies for benzene+p-xylene at 288.15, 198.15, 308.15, and 318.15 K

Excess enthalpies, excess volumes, and excess Gibbs free energies have been measured for benzene + p-xylene over the entire composition range at 288.15, 298.15,308.15, and 318,15 K. Excess enthalpies were measured in a mercury-displacement calorimeter, excess volumes were measured with a continuous-dilution tilting dilatometer, and excess Gibbs free energies were calculated from vapor-pressure measurements made with a continuous-dilution vapor-pressure apparatus. Excess heat capacities were calculated from the temperature dependence of the excess enthalpies. The results are compared with other work of the investigators. There is excellent agreement with the results of one of the investigators (J. B. Ott) obtained in another laboratory.

Excess volumes for tetrachloromethane + N,N-dimethylformamide, + N,N-dimethylacetamide, + p-dioxane, and + dimethylsulfoxide

Abstract Excess volumes have been determined over the entire composition range for tetrachloromethane + N,N-dimethylformamide and + N,N-dimethylacetamide at 283.15, 298.15, and 313.15 K; + p -dioxane at 288.15, 298.15, and 308.15 K; and + dimethylsulfoxide at 298.15 and 313.15 K. The negative excess volumes are correlated with the tendency to form charge-transfer complexes.