Water Ionization Constants at High Temperatures and Pressures Calculated with the “Isochoric” Model

Carbohydrates in thermophile metabolism: calculation of the standard molal thermodynamic properties of aqueous pentoses and hexoses at elevated temperatures and pressures

Correlation and prediction of thermodynamic properties of nonelectrolytes at infinite dilution in water over very wide temperature and pressure ranges (2000 K and 10 GPa)

The partial molar volume of n-alcohols at infinite dilution in water is smaller than the molar volume in the neat liquid phase. It is shown that the formula for the partial molar volume at infinite dilution obtained from the scaled particle theory equation of state for binary hard sphere mixtures is able to reproduce in a satisfactory manner the experimental data over a large temperature range. This finding implies that the packing effects play the fundamental role in determining the partial molar volume at infinite dilution in water also for solutes, such as n-alcohols, forming H bonds with water molecules. Since the packing effects in water are largely related to the small size of its molecules, the latter feature is the ultimate cause of the decrease in partial molar volume associated with the hydrophobic effect.

Chapter 13 - Diffusion Coefficient in Water – Inorganic Compounds

Apparent molar heat capacities and apparent molar volumes were measured for all isomeric C3 to C5 alkanols in their dilute aqueous solutions at 298.15 K using a differential flow microcalorimeter in conjuntion with a vibrating-tube densimeter. Molar volumes and molar heat capacities of the pure alkanols (except for 2-methyl-2-propanol and 2,2-dimethyl-1-propanol, which are solid at 298.15 K) were determined using the same instrumentation. The concentration dependence of the apparent properties allowed the determination, through extrapolation, of the infinite dilution partial molar volumes and heat capacities of these alkanols in water. These values, combined with the respective pure liquid properties, produced the limiting partial molar excess quantities ( , ). The present measurements agree well with available literature values. The group contribution schemes of Cabani et al. (Cabani, S.; Gianni, P.; Mollica, V.; Lepori, L. Group Contribution to the Thermodynamic Properties of Non-Ionic Organic Solutes i...

Chapter 12 - Diffusion Coefficient in Water – Organic Compounds

Solvation of N-methyl-2-pyrrolidone and N,N-dimethylpropanamide in cyclohexane, heptane, n-alkan-1-ols(C1–C4) and water at 298.15 K

In the mesosphere on Earth, water ice clouds are frequently observed in the low-temperature region (below -130℃) at altitudes 80-90 km in the polar region. Two mechanisms have been proposed to explain the formation of these ice particles. One is homogeneous nucleation, in which condensation nuclei are formed from water vapour. The other is heterogeneous nucleation, in which substrates such as aerosol in the atmosphere undergo a phase change as nuclei. The latest theoretical study shows that heterogeneous nucleation is predominant in the nucleation of mesospheric clouds on Earth and that homogeneous nucleation is unlikely to occur, when compared to observed conditions (Tanaka et al., 2022; https://doi.org/10.5194/acp-22-5639-2022). This theory may apply to cloud formation in other planetary atmospheres. On Mars, mesospheric clouds like those on Earth have been observed, but there are still many unresolved issues. In particular, the nucleation has only been studied theoretically by applying a classical theory for the lower atmospheric clouds (Määttänen et al., 2005). The purpose of this study is to clarify the nucleation mechanism of the Martian mesospheric clouds by comparing the mesospheric cloud observations obtained at Mars with theory of Tanaka et al. (2022).We used the solar occultation spectral data obtained by the ultraviolet (UV) to visible (VIS) channel UVIS of the Nadir and Occultation for MArs Discovery (NOMAD) spectrometer on board the ExoMars Trace Gas Orbiter (TGO) to clarify the purpose. The observational data considered this study consist in 9249 atmospheric transmission profiles covering the period from Ls (areocentric longitude of the sun) = 163°in MY (Martian Year) 34 to Ls = 218°in MY 36 (2018/4/22-2022/4/30) (Figure 1). In this study, we derive the total optical depth along the line of sight (slant opacity) from the transmittance spectra (Streeter et al., 2021). We attempt to distinguish between water ice clouds and dust by comparing the slant opacity at 320 nm, where we assume a large contribution from water ice clouds, with the slant opacity of all aerosols, including dust, at 600 nm. The existence of water ice clouds is determined under the conditions that the optical thickness at 320 nm is larger than 0.01 at altitudes of 40-100 km and the slant opacity ratio (320 nm / 600 nm) is larger than 1.5. The atmospheric density, dust density, atmospheric temperature and cooling rate, dust particle size, and water vapour pressure of the atmospheric conditions are estimated from the Mars Climate Database (MCD) (version 5.3; Millour et al., 2012), a numerical atmospheric general circulation model, and applied to the theory of Tanaka et al. (2022) to investigate the possibility of homogeneous and heterogeneous nucleation.Following the thresholds described above, Martian mesospheric water ice clouds were detected in 966 out of 9249 altitude distributions (152 in MY 34, 615 in MY 35, and 199 in MY 36). In addition, the relationship between clouds and the background atmospheric field was investigated, and it was clear that clouds tend to form under atmospheric conditions where the water vapor pressure is above 10-5 Pa and the temperature is below 200 K (Figure 2). Out of the 966 data, data were selected by saturated vapour pressure corresponding to every 10 K in the range of 130 K to 180 K. These were compared with the conditions obtained by Tanaka et al. (2022) for whether homogeneous or heterogenous nucleation predominates (Figure 3). The results suggested that when the background atmospheric water vapour pressure is above 1.56-5 Pa (saturated water vapour pressure at 150 K) at the time of cloud formation, the Martian atmosphere can only have atmospheric conditions where heterogeneous nucleation occurs, as on Earth. This result clarified that heterogeneous nucleation is predominant in the nucleation of mesospheric water ice clouds on Mars. On the other hand, when the water vapour pressure is less than 9.40-7 Pa (saturated water vapour pressure at 140 K), it was indicated that the Martian atmosphere can have atmospheric conditions that produce homogeneous nucleation. In fact, some of the clouds detected at altitudes above 70 km below the saturated water vapour pressure of 140 K suggested the possibilities of homogeneous nucleation. The latter is unexpected because it is a Mars-specific event that cannot occur on Earth. Detailed analysis of the dust density and dust particle size using the results derived from the instrument's observation data is needed in the future, to clarify the atmospheric conditions under which homogeneous nucleation can occur, which is not seen on Earth but is suggested on Mars. 

In this article, quantitative structure–property relationship (QSPR) models were developed for estimation of diffusion coefficients (DCs) of acids at infinite dilution in water. These models were obtained based on molecular descriptors of a set of 65 compounds at 298.15 K. Five date splits are randomly extracted from this dataset. Using a genetic algorithm (GA) variable-selection approach, five molecular descriptors in each split were selected from a set of thousand of them. To analyze the nonlinear behavior of these molecular descriptors, Adaptive neuro-fuzzy inference system (ANFIS) and radial basis function neural network (RBF NN) were used. These models were trained on 52 arbitrary sets of the data, and the remaining 13 sets were employed to evaluate the proposed models. Genetic function approximation (GFA) method could predict DCs of test dataset with high value of squared correlation coefficients of 0.984. QSPR model even gave superior predictions. ANFIS and RBF NN methods when implemented in QSPR model provided the squared correlation coefficients of 0.989 and 0.987, respectively. It is therefore suitable to be used in the proposed QSPR models, especially when applied with ANFIS method, to obtain DC of acids at infinite dilution in water instead of other expensive and complicated experiments.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDiffusion Coefficients at Infinite Dilution in Water and in N-MethylpyrrolidoneMarcel J. M. te Riele, Erwin D. Snijder, and Wim P. M. van SwaaijCite this: J. Chem. Eng. Data 1995, 40, 1, 34–36Publication Date (Print):January 1, 1995Publication History Published online1 May 2002Published inissue 1 January 1995https://pubs.acs.org/doi/10.1021/je00017a009https://doi.org/10.1021/je00017a009research-articleACS PublicationsRequest reuse permissionsArticle Views230Altmetric-Citations19LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Thermochemistry of solutions of biochemical model compounds 6. α,ω-dicarboxylic acids, -diamines, and -diols in aqueous solution

Henry's constants of gases and volatile organic compounds in aqueous solutions

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPartial molar volumbes of gases at infinite dilution in water at 298.15 KJoseph C. Moore, Rubin Battino, Timothy R. Rettich, Y. Paul Handa, and Emmerich WilhelmCite this: J. Chem. Eng. Data 1982, 27, 1, 22–24Publication Date (Print):January 1, 1982Publication History Published online1 May 2002Published inissue 1 January 1982https://doi.org/10.1021/je00027a005RIGHTS & PERMISSIONSArticle Views844Altmetric-Citations123LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (372 KB) Get e-Alerts Get e-Alerts

Experimental data on the partial molar volume at infinite dilution in water for two groups of organic solutes (derivatives of benzene and aliphatic hydroxyl derivatives) measured using a vibrating-tube densimeter in the temperature and pressure ranges 298 to 573 K and 0.1 to 30 MPa are summarized. Smoothed values of partial molar volume as a function of temperature and pressure are employed for the evaluation of group and structural contributions. The contributions are used to estimate the partial molar volumes at infinite dilution in water for various solutes. The average deviation between partial molar volumes calculated from the contributions and the experimental data employed for the evaluation of the contributions is less than 1 cm3ċmol−1 in most cases. Predictions of partial molar volumes of solutes not included in the evaluation of the contributions are performed and results are compared with experimental data.

This paper proposes a method by means of which the heat of solution at an infinite dilution of an organic compound in water, directly measured by means of calorimetry at a given temperature, is extended over a wide range of temperatures by the use of a phase diagram with water. The heat of solution at an infinite dilution in water over a temperature range from 290 to 350 K, which is estimated by this method for some alkanols and alkanoic acids, increases with a rise in the temperature and has a transition temperature from the exothermic region to the endothermic region which is close to the minimum dissolution temperature in the solubility curve in water for each substance. The increase in the heat of solution might be due to the breakdown of the iceberg formed around the alkyl group. The difference between the partial molar heat capacity at an infinite dilution and the molar heat capacity at the pure state, ΔScp\overset\ominus2, has its maximum at a certain temperature. The higher homolog shows a sharper curve with a lower maximum temperature. The curve of ΔScp\overset\ominus2vs. the temperature for 2- or 3-alkanol corresponds to that for the lower 1-alkanol. These facts reveal that a polar group, such as OH and COOH, would preferentially break the weaker structure of the iceberg within its breaking sphere, which structure should break down at a lower temperature.