A quantitative understanding of the thermochemistry of cyclohexadienyl radical and 1,4-cyclohexadiene is beneficial for diverse areas of chemistry. Given the interest in these two species, it is surprising that more detailed thermodynamic data concerning the homolytic C-H bond enthalpies of such entities have not been forthcoming. We thus undertook an experimental and computational evaluation o...

Microcalorimetry is an excellent method of determining the thermodynamics of ligand–protein binding in solution, because the signal being measured is the observed binding enthalpy (Db-obsH [Editors’ note: this term can also be written DHobs or DbHobs as seen elsewhere in this book]), which is free of any model assumptions. The affinity (DbG) can be computed from the shape of a binding curve, an...

Although many convincing, diverse, and sometimes competing models of glacier surging have been proposed, the observed behavior glaciers does not fit into distinct categories, suggests presence a universal mechanism driving all surges. On one hand, recent simulations oscillatory flow through description transient basal drag hint at fundamental underlying process. other proposition unified model ...

The heat capacity of specially prepared orthorhombic sulfur has been measured in a low-temperature adiabatic calorimeter. Measurements from T ~ 6 K to near the melting temperature transition at Tfug = 388.36 K are reported for equilibrium sulfur: for the orthorhombic modification from T » 6 K to the temperature of the orthorhombic-to-monoclinic transition Ttrg = 368.3 K, and for the monoclinic ...

The vaporization enthalpy of valproic acid (2-propylpentanoic acid) is reported, and the vapor pressures of a series on aliphatic carboxylic acids are used to evaluate its vapor pressure as a function of temperature. The vaporization enthalpy was derived by correlation-gas chromatography. This resulted in a vaporization enthalpy, ΔHvap(298.15 K) of (74.8 ± 2.4) kJ·mol−1. Vapor pressures from T/...

Intermolecular interactions involving aromatic pi-electron density are widely believed to be governed by the aromatic molecular quadrupole moment, Theta(zz). Arene-cation binding is believed to occur primarily with negative Theta(zz) aromatics, and arene-anion binding is believed to occur largely with positive Theta(zz) aromatics. We have performed quantum mechanical computations that show the ...

It is a challenge to calorimetrically determine the glass transition temperature (Tg) of vitreous silica. Here, we demonstrate that this challenge mainly arises from the extremely high sensitivity of the Tg to the hydroxyl content, but also from decrease of the Tg with repeating the calorimetric scans. It is known that the liquid fragility (i.e., the speed of the viscous slow-down of a supercoo...

Elution and solvation processes in liquid chromatography may be controlled by temperature changes. In the case of solvent adsorption, the temperature influences the amount of adsorbed solvent as well as the enthalpy and entropy of the solvation process. In this work, the thermodynamic parameters of organic solvents used as organic modifiers in the reversed-phase high-performance liquid chromato...

Thermodynamic adsorption properties (differential enthalpy and entropy, spreading pressure and net integral enthalpy and entropy) of cassava flour were determined at 25, 30 and 35°C to provide information about the water and energy requirements for the sorption process. The Guggenheim–Anderson–de Boer (GAB), Peleg and Halsey models were found to adequately describe the sorption characteristics,...

an analytical equation of state is applied to calculate the thermodynamic properties for argon. theequation of state is that of song and mason. it is based on a statistical-mechanical perturbation theory ofhard convex bodies and can be written as fifth-order polynomial in the density. there exist three temperaturedependentparameters: the second virial coefficient, an effective molecular volume,...