Volume 83, Issue 6

The 21st International Conference on Chemical Thermodynamics (ICCT-2010) was held in Tsukuba, Japan, on 1–6 August 2010, by the International Association of Chemical Thermodynamics (IACT) under the sponsorship of IUPAC. The organizing committee was chaired by Prof. T. Atake. The conference attracted more than 600 scientists from 37 different countries. During the conference period, the Rossini lecture and 9 plenary lectures were delivered. Forty invited papers and approximately 200 contributed papers were presented in 7 parallel sessions, together with about 300 poster presentations. The wide variety of fields in chemical thermodynamics is illustrated by the titles of a number of the symposia: “Fluids and fluid mixtures”, “Phase equilibria”, “Foods and pharmaceuticals”, “Biothermodynamics”, “Colloids and interfaces”, “Thermochemistry and molecular energetics”, “Environmental issues”, “Industrial applications, databases and software”, “Theory and simulation”, “Organic materials and polymers”, “Inorganic materials and metals”, “New techniques”, “Education in chemical thermodynamics”, and a special session in honor of Profs. S. Seki and H. Suga. As part of the scientific program, two workshops were also held, the titles of which are: “Energy in subsections on petroleum, coal and alternative sources”, and “Calorimetry with commercial relaxation instruments”. This issue of Pure and Applied Chemistry collects four selected plenary lectures delivered at the conference. The topics include challenges in teaching thermodynamics, new equations-of-state model of fluids and their mixtures, Gibbs energy minimization method in multiphase equilibria, and critical evaluation of thermophysical properties database in chemical process simulation. In these papers, we hope that the readers find the essence of the various aspects of current exciting research in chemical thermodynamics, which were exhibited in a lively manner during this successful conference. Other general papers presented in the symposia and workshops will be published in J. Chem. Thermodynamics , Thermochimica Acta , and Molecular Simulation . The 22nd ICCT is scheduled to be held August 2012 in Búzios, Brazil. Masaki Akaogi Makoto Aratono Conference Editors

I consider the challenges of sharing thermodynamic concepts with both the general public and with students, whom I regard mostly as students of chemistry. I deal with the following challenges: (1) The order of presentation: what are the issues relating to presenting thermodynamics before or after quantum theory? (2) What should we identify as the foundations of our subject? (3) How do we convey to the general public (and the starting student) the insights that we get from the Second Law? (4) How do we bridge the gap from the qualitative to the quantitative? (5) Does visualization of calculations and concepts always help or can it make matters more complicated? (6) How do we make the transition to discussions in terms of Helmholtz and Gibbs energies, and start doing chemically useful calculations? (7) How do we keep track of the seemingly overwhelmingly large number of equations that a systematic treatment of thermodynamics inevitably generates? (8) How should we introduce statistical thermodynamics and enrich our understanding of classical thermodynamics? (9) How do we extend calculations to show the fascinating and broad scope of elementary thermodynamics?

The basic objective of this work is the development of an approximate, yet coherent and consistent equation-of-state model of fluids, which will benefit from recent developments in the successful COnductor-like Screening MOdel (COSMO)-type group-contribution models with their quantum-mechanical description of fluids. The development is done within our recent non-random hydrogen-bonding (NRHB) equation-of-state framework. In contrast to NRHB, the new model will not need any new parameters for the strong specific interactions, such as hydrogen bonds, since they will be provided by its COSMO component and the associated quantum-chemistry calculations. The bridge between COSMO and NRHB is the non-randomness factors as calculated by the quasi-chemical treatment of the non-random distribution of molecular entities in the system. Analytical expressions are provided for all basic thermodynamic quantities, including expressions for the cavitation and charging components of the solvation Gibbs energy. The new equation-of-state model is tested against experimental data for vapor pressures, heats of vaporization, and liquid densities of pure fluids and on phase equilibria of mixtures. The strength and perspectives of the new model are critically discussed.

The conventional Gibbs energy minimization methods apply elemental amounts of system components as conservation constraints in the form of a stoichiometric conservation matrix. The linear constraints designate the limitations set on the components described by the system constituents. The equilibrium chemical potentials of the constituents are obtained as a linear combination of the component-specific contributions, which are solved with the Lagrange method of undetermined multipliers. When the Gibbs energy of a multiphase system is also affected by conditions due to immaterial properties, the constraints must be adjusted by the respective entities. The constrained free energy (CFE) minimization method includes such conditions and incorporates every immaterial constraint accompanied with its conjugate potential. The respective work or affinity-related condition is introduced to the Gibbs energy calculation as an additional Lagrange multiplier. Thus, the minimization procedure can include systemic or external potential variables with their conjugate coefficients as well as non-equilibrium affinities. Their implementation extends the scope of Gibbs energy calculations to a number of new fields, including surface and interface systems, multi-phase fiber suspensions with Donnan partitioning, kinetically controlled partial equilibria, and pathway analysis of reaction networks.

Accurate thermophysical properties are essential to the development of high-quality process simulation models of chemical processes. Therefore, process-modeling software (simulator) must provide accurate, reliable, and easily accessible property data and models to enable efficient and robust process design. Property data and parameters for components of interest are generally available in the databases of the simulator. For components that are not in the databases, their property data must be supplied by the user. The number of components available in a typical simulator is about 1700. The number and types of components available in the simulator limit the scope and accuracy of process models that can be developed. In this paper, we review past practice in obtaining the necessary property data required in developing a process model and describe a new methodology that can be used to overcome the shortcomings of the current method. The new method is based on the dynamic data evaluation concept that combines the experimental data obtained from a comprehensive electronic database with structure-based property estimation system and data analysis and regression programs to generate critically evaluated property data. The concept and necessary software have been implemented in a process simulator, resulting in a new workflow that enables high-fidelity process models to be developed more easily and efficiently.

Aqueous-phase chemical generation of volatile hydrides (CHG) by derivatization with borane complexes is one of the most powerful and widely employed methods for determination and speciation analysis of trace and ultratrace elements (viz. Ge, Sn, Pb, As, Sb, Bi, Se, Te, Hg, Cd, and, more recently, several transition and noble metals) when coupled with atomic and mass spectrometric detection techniques. Analytical CHG is still dominated by erroneous concepts, which have been disseminated and consolidated within the analytical scientific community over the course of many years. The overall approach to CHG has thus remained completely empirical, which hinders possibilities for further development. This report is focused on the rationalization and clarification of fundamental aspects related to CHG: (i) mechanism of hydrolysis of borane complexes; (ii) mechanism of hydrogen transfer from the borane complex to the analytical substrate; (iii) mechanisms through which the different chemical reaction conditions control the CHG process; and (iv) mechanism of action of chemical additives and foreign species. Enhanced comprehension of these different mechanisms and their mutual influence can be achieved in light of the present state of knowledge. This provides the tools to explain the reactivity of a CHG system and contributes to the clarification of several controversial aspects and the elimination of erroneous concepts in CHG.

Retraction: Morphology and mechanics of the adhesive disc of liana Parthenocissus tricuspidata (T. He, L. Zhang, H. Xin, W. Deng). Pure Appl. Chem. 82, 91–96 (2010); doi:10.1351/PAC-CON-08-12-06.