Showing papers on "Enthalpy published in 1991"

SGTE data for pure elements

Abstract: Thermodynamic data for the condensed phases of 78 elements as currently used by SGTE (Scientific Group Thermodata Europe) are tabulated. SGTE is a consortium of seven organisations in Western Europe engaged in the compilation of a comprehensive, self consistent and authoritative thermochemical database for inorganic and metallurgical systems. The data are being published here in the hope that they will become widely adopted within the international community as a sound basis for the critical assessment of thermodynamic data, thereby, perhaps, limiting unnecessary duplication of effort. The data for each phase of each element considered aie presented as expressions showing, as a function of temperature, the variation of (a) G-HSER, the Gibbs energy relative to the enthalpy of the “Standard Element Reference” ie the reference phase for the element at 298.15 K and (b) the difference in Gibbs energy between each phase and this reference phase (ie lattice stability). The variation of the heat capacity of the various phases and the Gibbs energy difference between phases are also shown graphically. For certain elements the thermodynamic data have been assessed as a function of pressure as well as temperature. Where appropriate a temperature— pressure phase diagram is also shown. Throughout this paper the thermodynamic data are expressed in terms of J mol−1. The temperatures of transition between phases have been assessed to be consistent with the 1990 International Temperature Scale (ITS90).

CRC Handbook of Solubility Parameters and Other Cohesion Parameters, Second Edition

Abstract: INTRODUCTION THERMODYNAMICS Cohesive Energy Cohesive Pressure and the Hildebrand Parameter Thermodynamic Equation of State Empirical Equations of State Units and Conversion Factors Mixtures Phase Separation MOLECULAR INTERACTIONS Electrical Properties Dipole-Dipole Interactions Dipole-Induced Dipole Interactions Induced Dipole-Induced Dipole Interactions Spectroscopic Studies Positron Annihilation REGULAR SOLUTIONS AND THE HILDEBRAND PARAMETER Geometric Mean Approximation Hildebrand-Scatchard Equation Limitations of the Hildebrand-Scatchard Equation Mixed Liquids and Multicomponent Systems Solvent Spectra Wilson Equation EXPANDED COHESION PARAMETERS Dispersion Orientation Induction Lewis Acid-Base Hydrogen-Bonding Association Combination of Component Cohesion Parameters Empirical Corrections for Geometric Mean Deviations Polar-Nonpolar Cohesion Parameters Hansen Parameters Fractional Three-Component Cohesion Parameters Other Two- and Three-Component Cohesion Parameters Other Multi-Component Cohesion Parameters Modified Separation of Cohesive Energy Density Liquid Metals CALCULATED COHESION PARAMETERS Group Molar Vaporization Enthalpy Group Molar Cohesive Energy Molar Additive Functions Group Molar Attraction Constants Group Molar Volumes Group Cohesion Parameters Homomorphs and Dispersion Cohesion Parameters Hansen Parameter Group Contributions Participating and Nonparticipating Groups Comparison of Methods LIQUID PHASES Vaporization Enthalpy Vapor Pressure Boiling Point Corresponding States Internal Pressure and Cohesive Pressure Liquid-Liquid Miscibility Binary Solvents Activity Coefficients in Liquid-Liquid Systems Complexes Solvent-Aided Separation Liquid Extraction Acidity-Basicity Linear Energy Scales SOLVENT SCALES Hydrogen Bonding Electrostatic Parameters and Empirical Relationships Single Component Donor-Acceptor Parameters Hybrid Cohesion Parameter Solvent Scales Practical Solvent Scales EFFECTS OF PHYSICAL CONDITIONS Temperature Density, Volume and Pressure Concentration KINETIC AND TRANSPORT PROCESSES Kinetic Solvent Effects Transition State Theory Rates and Mechanisms Polymerization and Polymer Reactions Viscosity Other Time-Dependent Properties GASES Nomenclature Hildebrand Parameters and Gas Solubilities Compressed Gases Supercritical Extraction Vapor-Liquid Equilibria in Mixtures Henry's Law SOLIDS Activities and Solubilities Cohesion Parameters for Nonionic Solid Solutes Ionic Systems POLYMER SOLUTIONS Physical Properties of Polymers The Polymer-Liquid Reference Solution Polymer-Liquid Interaction Parameters Limitations on Interaction Parameters Interaction Parameters and Cohesion Parameters Cosolvency and Co-Nonsolvency Theta Temperature and Theta Solvents Segment Interaction Equation DETERMINATION OF POLYMER COHESION PARAMETERS Hildebrand Parameter Values Hildebrand Parameters from Polymer-Liquid Interaction Parameters Solubility/Swelling Spectrum Methods Turbidimetric Titrations Hansen Parameters Other Cohesion Parameters Solution Viscosity Calculation of Polymer Cohesion Parameters Effects of Temperature, Concentration, Molecular Weight POLYMER MAPS AND MODELS Cohesion Parameter Maps and Models Hybrid Maps and Models CORRELATION OF POLYMER PROPERTIES WITH COHESION PARAMETERS Electrical Properties Mechanical Properties Thermal Transitions and Plasticization Environment-Induced Degradation Radiation Interactions With Gases and Liquids Permeation Interactions With Low Molecular Weight Solids Polymer-Polymer Interactions Copolymers Natural Polymers SURFACES AND INTERFACES Interfacial Free Energy Interfacial Free Energies and Cohesion Parameters Component Surface Free Energies and Cohesion Parameters Multicomponent Systems Wetting, Adhesion, Lubrication, Powders Adsorption Micelles, Colloids, Emulsions, Foams, Surfactants Dispersion of Pigments and Dyes Surface Contamination and Cleaning CHROMATOGRAPHY Component Cohesion Parameter Expressions GLC Interactions of Polymers and Plasticizers With Liquids GLC Studies of Nonpolymer Systems Liquid Chromatography Supercritical Fluid Chromatography Liquid-Solid Chromatography and Gel Chromatography BIOLOGICAL SYSTEMS Hansch Lipophilic Parameter Effects and Transmission Rates of Biologically-Active Materials Prosthetic Materials Other Biological Systems

Solvent reorganization contribution to the transfer thermodynamics of small nonpolar molecules.

Abstract: The experimental thermodynamic data for the dissolution of five simple hydrocarbon molecules in water were combined with the solute-solvent interaction energy from a computer simulation study to yield data on the enthalpy change of solvent reorganization. Similar data were generated for dissolving these same solute molecules in their respective neat solvents using the equilibrium vapor pressure and the heat of vaporization data for the pure liquid. The enthalpy and the free energy changes upon cavity formation were also estimated using the temperature dependence of the solute-solvent interaction energy. Both the enthalpy and T delta S for cavity formation rapidly increase with temperature in both solvent types, and the free energy of cavity formation can be reproduced accurately by the scaled particle theory over the entire temperature range in all cases. These results indicate that the characteristic structure formation around an inert solute molecule in water produces compensating changes in enthalpy and entropy, and that the hydrophobicity arises mainly from the difference in the excluded volume effect.

Nonclassical hydrophobic effect in membrane binding equilibria.

Abstract: The enthalpy of transfer of four different amphiphilic molecules from the aqueous phase to the lipid membrane was determined by titration calorimetry. The four molecules investigated were the potential-sensitive dye 2-(p-toluidinyl)naphthalene-6-sulfonate (TNS), the membrane conductivity inducing anion tetraphenylborate (TPB), the Ca2+ channel blocker amlodipine [Bauerle, H. D., & Seelig, J. (1991) Biochemistry 30, 7203-7211], and the positively charged local anesthetic dibucaine. All four amphiphiles penetrate into the hydrophobic part of the membrane, and their binding constants, after correcting for electrostatic effects, range between 600 M-1 for dibucaine and 60,000 M-1 for tetraphenylborate. The corresponding changes in free energy were about -6 to -9 kcal/mol. Binding of the amphiphiles to membrane vesicles composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine was accompanied by exothermic heats of reaction for all four molecules. For TNS, TPB, and amlodipine, the enthalpies of transfer were almost identical and corresponded to delta H approximately -9 kcal/mol, essentially accounting for the total free energy change. Thus, the binding of these charged amphiphiles to the hydrophobic membrane was driven by enthalpy. This is in contrast to the classical hydrophobic effect, where the transfer is considered to be entropy driven. For dibucaine, the enthalpy of transfer was smaller with delta H approximately -2 kcal/mol but was still about one-third of the total free energy change. All enthalpies of transfer exhibited a distinct temperature dependence with molar heat capacities delta Cp of -30 to -100 cal mol-1K-1 for the transfer from water to the membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Critical evaluation of stability constants for nucleotide complexes with protons and metal ions and the accompanying enthalpy changes

Abstract: Chairman: L. D. Pettit (UK): Secretary: 0. Yamauchi (Japan); Titular Members: A. Braibani (Italy); D. G. Tuck (Canada); P. Valenta (FRG); Associate Members: A. C. M. Bourg (France); I. R. Grenthe (Sweden); B. Holmberg (Sweden), T. A. Kaden (Switzerland); T. Kiss (Hungary); P. A. Manorik (USSR); R. B. Martin (USA); P. Paoletti (Italy); R. Portanova (Italy); K. J. K. Powell (New Zealand); National Representatives: L. H. J. Lajunen (Finland); M. T. Beck (Hungary); P. K. Bhattacharya (India); H. Ohtaki (Japan); C. Luca (Romania); S. Ahrland (Sweden); G. R. Choppin (USA). t Series Title: Critical Evaluation of Stability Constants of Metal Complexes in Solution.

Pressure‐enhanced crystallization kinetics of amorphous Si and Ge: Implications for point‐defect mechanisms

Abstract: The effects of hydrostatic pressure on the solid‐phase epitaxial growth (SPEG) rate v of intrinsic Ge(100) and undoped and doped Si(100) into their respective self‐implanted amorphous phases are reported. Samples were annealed in a high‐temperature, high‐pressure diamond anvil cell. Cryogenically loaded fluid Ar, used as the pressure transmission medium, ensured a clean and hydrostatic environment. v was determined by in situ time‐resolved visible (for Si) or infrared (for Ge) interferometry. v increased exponentially with pressure, characterized by a negative activation volume of −0.46Ω in Ge, where Ω is the atomic volume, and −0.28Ω in Si. The activation volume in Si is independent of both dopant concentration and dopant type. Structural relaxation of the amorphous phases has no significant effect on v. These and other results are inconsistent with all bulk point‐defect mechanisms, but consistent with all interface point‐defect mechanisms, proposed to date.A kinetic analysis of the Spaepen–Turnbull interfacial dangling bond mechanism is presented, assuming thermal generation of dangling bonds at ledges along the interface, independent migration of the dangling bonds along the ledges to reconstruct the network from the amorphous to the crystalline structure, and unimolecular annihilation kinetics at dangling bond ‘‘traps.’’ The model yields v = 2 sin(θ)vsnr exp[(ΔSf + ΔSm)/k] exp− [(ΔHf + ΔHm)/kT], where ΔSf and ΔHf are the standard entropy and enthalpy of formation of a pair of dangling bonds, ΔSm and ΔHm are the entropy and enthalpy of motion of a dangling bond at the interface, vs is the speed of sound, θ is the misorientation from {111}, and nr is the net number of hops made by a dangling bond before it is annihilated. It accounts semiquantitatively for the measured prefactor, orientation dependence, activation energy, and activation volume of v, and the pressure of a ‘‘free‐energy catastrophe’’ beyond which the exponential pressure enhancement of SPEG cannot continue uninterrupted due to a vanishing barrier to dangling bond migration. The enhancement of v by doping can be accounted for by an increased number of charged dangling bonds, with no change in the number of neutrals, at the interface. Quantitative models for the doping dependence of v are critically reviewed. At low concentrations the data can be accounted for by either the fractional ionization or the generalized Fermi‐level‐shifting models; methods to further test these models are enumerated. Ion irradiation may affect v by altering the populatio

Thermodynamic Properties of the Aqueous Sulfuric Acid System to 350 K

Abstract: Experimental measurements for aqueous sulfuric acid and its related pure, solid phases have been thermodynamically analyzed and correlated as a function of temperature and composition from pure water to pure acid. The pure phases included anhydrous sulfuric acid, five of its hydrates and ice. Experimental data which were used in the correlation included measurements of the enthalpy of dilution, both solution and pure phase heat capacities, electromotive force and solution freezing points. The correlation yielded mutually consistent expressions for the Gibbs energy of each phase and these functions generally reproduce the experimental data to ±0.75 percent. The Gibbs energy functions of the pure solid phases were used to generate tables of their thermodynamic properties from 0 K to the melting points. The Gibbs energy function for aqueous sulfuric acid was used to produce tables of both integral and partial molar solution properties as a function of sulfuric acid mole fraction every 50° from 200 to 350 K.

Isoenthalpic and isoentropic temperatures and the thermodynamics of protein denaturation.

Abstract: The standard enthalpy or entropy change upon transfer of a small nonpolar molecule from a nonaqueous phase into water at a given temperature is generally different for different solute species. However, if the heat capacity change is independent of temperature, there exists a temperature at which the enthalpy or the entropy change becomes the same for all solute species within a given class. Similarly, the enthalpy or the entropy change of protein denaturation, when extrapolated to high temperature assuming a temperature-independent heat capacity change, shows a temperature at which its value becomes the same for many different globular proteins on a per weight basis. It is shown that the existence of these temperatures can be explained from a common formalism based on a linear relationship between the thermodynamic quantity and a temperature-independent molecular property that characterizes the solute or the protein. For the small nonpolar molecule transfer processes, this property is the surface area or the number of groups that are brought in contact with water. For protein denaturation, it is suggested that this property measures the polar/nonpolar mix of the internal interaction within the protein interior. Under a certain set of assumptions, this model leads to the conclusion that the nonpolar and the polar groups of the protein contribute roughly equally to the stability of the folded state of the molecule and that the solvent-accessible surface area of the denatured form of a protein is no more than about two-thirds that of the fully extended form.

Direct calorimetric analysis of the enzymatic activity of yeast cytochrome c oxidase.

Abstract: The kinetic and thermodynamic parameters associated with the enzymatic reaction of yeast cytochrome c oxidase with its biological substrate, ferrocytochrome c, have been measured by using a titration microcalorimeter to monitor directly the rate of heat production or absorption as a function of time. This technique has allowed determination of both the energetics and the kinetics of the reaction under a variety of conditions within a single experiment. Experiments performed in buffer systems of varying ionization enthalpies allow determination of the net number of protons absorbed or released during the course of the reaction. For cytochrome c oxidase the intrinsic enthalpy of reaction was determined to be -16.5 kcal/mol with one (0.96) proton consumed for each ferrocytochrome c molecule oxidized. Activity measurements at salt concentrations ranging from 0 to 200 mM KCl in the presence of 10 mM potassium phosphate, pH 7.40, and 0.5 mM EDTA display a biphasic dependence of the electron transferase activity upon ionic strength with a peak activity observed near 50 mM KCl. The ionic strength dependence was similar for both detergent-solubilized and membrane-reconstituted cytochrome c oxidase. Despite the large ionic strength dependence of the kinetic parameters, the enthalpy measured for the reaction was found to be independent of ionic strength. Additional experiments involving direct transfer of the enzyme from low to high salt conditions produced negligible enthalpy changes that remained constant within experimental error throughout the salt concentrations studied (0-200 mM KCl). These results indicate that the salt effect on the enzyme activity is of entropic origin and further suggest the absence of a major conformational change in the enzyme due to changes in ionic strength.(ABSTRACT TRUNCATED AT 250 WORDS)

On the partial atomic volume and the partial molar enthalpy of aluminium in some phases with Cu and Cu3Au structures

Abstract: The lattice parameters and macroscopic densities of the solid solutions of Co(Al), Rh(Al), Ir(Al), Ni(Al), Cu(Al), Ag(Al) and Au(Al) and the intermetallic compounds of Ni 3 Al and Ag 2 Al were measured over the whole range of homogeneity. The dependence of both the average atomic volume and the enthalpy of formation on mole fraction was investigated for the systems A 9 -Al ( A 9 ≡ Co , Rh , Ir ), A 10 -Al ( A 10 ≡ Ni , Pd , Pt ) and B 11 -Al ( B 11 ≡ Cu , Ag , Au ). The partial atomic volume and the partial molar enthalpy of aluminium were analysed for phases with the Cu and Cu 3 Au structures. Among the quasi-homological systems, the smallest values for the partial atomic volume of aluminium and the most negative values for the partial molar enthalpy of aluminium were found in the solid solutions A 10 (Al). These indicate a strong charge transfer from aluminium-atoms to atoms of nickel, palladium and platinum.

Thermodynamic Properties of Oxygen from the Triple Point to 300 K with Pressures to 80 MPa

Abstract: A joint project by the authors has resulted in two new thermodynamic property formulations for oxygen. The fundamental equation explicit in Helmholtz energy by Schmidt and Wagner has been used for the calculation of the property tables presented here, and for comparisons of calculated properties to the experimental data. The formulation of Stewart and Jacobsen is used in this paper in comparisons of properties calculated by the two formulations. These comparisons provide the basis for independent assessment of the accuracy of the available data and calculated properties. The procedures used in determining the formulations by Wagner and Schmidt, and by Stewart and Jacobsen were published earlier. The fundamental equation is valid for thermodynamic properties of oxygen from the freezing line to 300 K at pressures to 80 MPa. A separate vapor pressure equation and equations for the saturated liquid and saturated vapor densities and the ideal gas heat capacity are included. Functions for calculating internal e...

Calculations and curve fits of thermodynamic and transport properties for equilibrium air to 30000 K

Abstract: A self-consistent set of equilibrium air values were computed for enthalpy, total specific heat at constant pressure, compressibility factor, viscosity, total thermal conductivity, and total Prandtl number from 500 to 30,000 K over a range of 10(exp -4) atm to 10(exp 2) atm. The mixture values are calculated from the transport and thermodynamic properties of the individual species provided in a recent study by the authors. The concentrations of the individual species, required in the mixture relations, are obtained from a free energy minimization calculation procedure. Present calculations are based on an 11-species air model. For pressures less than 10(exp -2) atm and temperatures of about 15,000 K and greater, the concentrations of N(++) and O(++) become important, and consequently, they are included in the calculations determining the various properties. The computed properties are curve fitted as a function of temperature at a constant value of pressure. These curve fits reproduce the computed values within 5 percent for the entire temperature range considered here at specific pressures and provide an efficient means for computing the flowfield properties of equilibrium air, provided the elemental composition remains constant at 0.24 for oxygen and 0.76 for nitrogen by mass.

Middle atmosphere heating by exothermic chemical reactions involving odd-hydrogen species

Abstract: The rate of heating which occurs in the middle atmosphere due to four exothermic reactions involving members of the odd-hydrogen family is calculated. The following reactions are considered: O + OH yields O2 + H; H + O2 + M yields HO2 + M; H + O3 yields OH + O2; and O + HO2 yields OH + O2. It is shown that the heating rates due to these reactions rival the oxygen-related heating rates conventionally considered in middle-atmosphere models. The conversion of chemical potential energy into molecular translational energy (heat) by these odd-hydrogen reactions is shown to be a significant energy source in the middle atmosphere that has not been previously considered.

Thermodynamic excess properties of alkanol + amine mixtures and application of the ERAS model

Abstract: New experimental data of the molar excess volume VE of the mixtures ethanol/n-butylamine, heptanol/n-butylamine, n-propanol/dibutylamine have been obtained using the technique of the vibrating tube densitometer. Together with the data for the molar excess enthalpy HE from the literature, the VE data have been used for testing the applicability of the socalled ERAS model which accounts for hydrogen bonding effects as well as for free volume effects in associating mixtures. The results obtained by adjusting the model parameters reveal a strong cross association between the unlike molecules in the mixture resulting from strong negative values for the hydrogen bonding energy and the hydrogen bonding volume.

Adam-Gibbs formulation of non-linear enthalpy relaxation

Abstract: The Adam-Gibbs (AG) expression linking relaxation times with configurational entropy gives a good account of the non-linearity observed in enthalpy relaxation of amorphous polymeric, inorganic, and simple molecular materials near and below Tg. Data analyses yield zero-entropy temperatures that are comparable with available Kauzmann values. The AG formulation, when coupled with a few plausible ancillary assumptions, predicts correlations between the Arrhenius parameters x, Δh ∗ , and the KWW exponent β that are observed experimentally. It is suggested that the AG primary activation energy, Δμ, is the single causative factor that generates these correlations.

Removal of ni(II) from aqueous solutions by sorption

Abstract: Adsorption of Ni(II) from its aqueous solutions on China clay, a cheap clay mineral, has been found quite favourable; a maximum removal of 75.3% was obtained at 50 mg L‐1 metal concentration and a pH of 6.5 at 30°C. Dynamic modelling of the nickel uptake has been worked out and found to be of the first order. The rate constant was found to be 9.21 x 10‐1 min‐1 under the above optimum conditions of the experiment. Coefficients of the mass transfer and intraparticle diffusion were also evaluated and found to be 2.8 x 10‐2 cm s‐1 and 4.50 x 10‐2 cm2 s‐1 respectively. Langmuir's model was used for the equilibrium modelling and the constants were calculated at 30, 40 and 50°C. Thermodynamic study at different temperatures was undertaken and the values of change in the standard free energy (?G°), enthalpy (?H°) and entropy (?S°) are reported. Low temperature and high pH favour the removal of nickel (II) by adsorption on China clay.

Thermal properties of β‐Mg2SiO4 at mantle pressures derived from vibrational spectroscopy: Implications for the mantle at 400 km depth

Abstract: The pressure dependences of 25 Raman modes of β-Mg2SiO4 were measured to 235 kbar. The thermodynamic parameters, heat capacity, GV, and entropy, S, of β-Mg2SiO4 were calculated using a statistical approach from information derived from the spectra. CV and S calculated from the 1-atm data agree well with the available previous calorimetric data and previous lattice dynamical calculations. The high pressure data were used to calculate the pressure dependence of CV and S. From these data and those from previous spectroscopic measurements on forsterite at high pressures, previous enthalpy data, and the equations of state of both phases, the equilibrium phase boundary was calculated to be P(kbar) = 101 + 0.027 kbar-K−1×T(K), agreeing exactly with new phase equilibrium data. The Clapeyron slope, ΔS/ΔV, for the forsterite to β-Mg2SiO4 transition was found to be nearly constant for a large P-T range, indicating that the pressure and temperature induced volume changes compensate for the pressure and temperature induced entropy changes for the transition. Using the equation of state of both minerals at equilibrium conditions and the thermal expansion systematics of δT = 5.5 ± 0.5, the sound velocity increases across the forsterite to β-phase transition by approximately 7.5%. Thus, a mantle of ∼ 60% olivine, i.e., a pyrolitic mantle, could account for the average seismic sound velocity change of +4.5% at 400 km depth. In addition, at 92 kbar, strong decreases in the pressure derivative of 7 Raman modes indicate changes in the compression mechanism of the β-Mg2SiO4 lattice. Similar observations for forsterite at the same pressure imply that similar elastic limits were reached within the respective lattices. This phenomenon is interpreted as a second-order phase transition.

Application of linear free energy relations to protein conformational changes : the quaternary structural change of hemoglobin

Abstract: The transition state for the R in equilibrium with T quaternary conformational change of hemoglobin has thermodynamic properties much closer to those of the R conformation than to those of the T conformation. This finding is based on a comparison of activation and equilibrium enthalpy and entropy changes and on the observation of a linear free energy relationship between quaternary rate and equilibrium constants. A previous theoretical study [Janin, J. & Wodak, S. J. (1985) Biopolymers 24, 509-526], using a highly simplified energy function, suggests that the R-like transition state is the result of a reaction pathway with the maximum buried surface area between alpha beta dimers.

Prediction of the thermodynamics of protein unfolding: the helix-coil transition of poly(L-alanine).

Abstract: The method given earlier for predicting the thermodynamics of protein unfolding from the x-ray structure of a protein is applied here to the poly(L-alanine) helix. First, the fitting parameters derived earlier from a data base of 10 proteins were used to predict the unfolding thermodynamics of 4 other proteins. The agreement between the observed and predicted values is comparable to that found for the 10 proteins studied initially. Next, the temperature dependences of the Gibbs energy and enthalpy changes for unfolding of bacteriophage T4 lysozyme were predicted and compared with data in the literature. The predicted and observed temperature dependences are similar and the predicted results indicate that cold denaturation should be observed at low temperatures, as observed recently for a T4 lysozyme mutant. The fitting parameters derived from thermodynamic data for protein unfolding and for hydration of model compounds were used to predict the unfolding thermodynamics of the poly(L-alanine) helix. The results predict that helix formation is enthalpy-driven, and the predicted enthalpy change for unfolding (0.86 kcal per mol per residue) is close to the value found in a recent calorimetric study of a 50-residue alanine-rich helix.

Sixteen Thousand Evaluated Experimental Thermodynamic Property Data for Water and Steam

Abstract: As part of the activities of the International Association for the Properties of Water and Steam, all reliable sources of experimental data on the thermodynamic properties of ordinary (light) water and steam have been collected and converted to common temperature, pressure, volume, mass and heat scales. The data are grouped by state or phase: ideal‐gas properties; sublimation and melting curves; saturation properties; properties of liquid water at ambient pressure; thermodynamic properties of the single‐phase state; and those of metastable states. In each category, a subdivision is made by property. Properties include the volume, enthalpy, heat capacities, sound velocity, internal energy and Joule‐Thomson and related coefficients. The total data collection contains approximately 16 000 data points and covers a century of experimental work at temperatures from 253 to 1273 K and pressures up to 1 GPa. This report characterizes the data and gives the literature references. The actual data collection is avail...