Electron ionization (EI) mass spectra of saturated carbocyclic hydrocarbons containing a single ring with three or more members are discussed followed by the examination of their unsaturated analogs, including aromatic hydrocarbons. Mass spectrometry characteristics of heterocyclic compounds for each cycle size with one, two, three, and more hetero-atoms in a ring are considered along with their mono- and polyunsaturated analogs. An effect of the (a) size of a cycle; (b) number, nature, and location of elements in a ring; (c) position and nature of ring substituents; and (d) nature and location of unsaturation on the dissociation is revealed. Characteristic dissociation directions of these compounds and diagnostically important ions in their spectra are identified. Basic dissociation rules for alicyclic, heterocyclic, and aromatic compounds under EI are established for further use in the analysis of complex chemicals containing these structural elements.
{"title":"Protocol for structure determination of unknowns by EI mass spectrometry. II. Diagnostic ions in one ring alicyclic, heterocyclic, and aromatic compounds","authors":"A. Mikaia","doi":"10.1063/5.0140771","DOIUrl":"https://doi.org/10.1063/5.0140771","url":null,"abstract":"Electron ionization (EI) mass spectra of saturated carbocyclic hydrocarbons containing a single ring with three or more members are discussed followed by the examination of their unsaturated analogs, including aromatic hydrocarbons. Mass spectrometry characteristics of heterocyclic compounds for each cycle size with one, two, three, and more hetero-atoms in a ring are considered along with their mono- and polyunsaturated analogs. An effect of the (a) size of a cycle; (b) number, nature, and location of elements in a ring; (c) position and nature of ring substituents; and (d) nature and location of unsaturation on the dissociation is revealed. Characteristic dissociation directions of these compounds and diagnostically important ions in their spectra are identified. Basic dissociation rules for alicyclic, heterocyclic, and aromatic compounds under EI are established for further use in the analysis of complex chemicals containing these structural elements.","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49546867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Arcis, Christopher A. Lee, G. H. Zimmerman, P. Tremaine
High-temperature tracer diffusion coefficients for H3O+ and OH− are important parameters in the modeling of diffusion-controlled reaction kinetics and mass transport processes under hydrothermal conditions, and these tracer diffusion coefficients are directly related to the ionic electrical conductivities in the limit of infinite dilution through the Nernst–Einstein relationship. The limiting conductivity of H3O+ and OH− in water is controlled by two separate mechanisms of ionic movement: (i) the bulk ionic diffusion and (ii) proton hopping, also known as “Grotthuss” mechanism and/or “prototropic transfer.” This work reports a critical assessment of the limiting electrical conductivity data (Λ°) for aqueous HCl, KOH, and NaOH measured above room temperature. The initial assessed dataset included temperatures from 273.15 K up to 873.15 K and water densities from 1000 kg m−3 down to 270 kg m−3 and was reduced down to a final critically evaluated dataset spanning temperatures between 273.15 and 678.15 K and densities between 346 and 1006 kg m−3. The results were used to derive values for the excess conductivity due to prototropic transfer, λE°, of H3O+ and OH− using correlations previously reported for aqueous KCl. Simple empirical correlations of water viscosity and density were derived for Λ°(HCl), Λ°(KOH), Λ°(NaOH), λE°(H3O+), and λE°(OH−). Tests using the λE°(OH−) correlation and a previously reported function for Λ°(NaCl) show that the NaOH data can be accurately reproduced to within the estimated uncertainties. The reported correlations provide a means to model more accurately the tracer diffusion coefficients for H3O+ and OH− to supercritical conditions.
高温示踪剂h30 +和OH−的扩散系数是水热条件下扩散控制反应动力学和质量传递过程建模的重要参数，这些示踪剂扩散系数通过能思-爱因斯坦关系与无限稀释极限下的离子电导率直接相关。h30 +和OH−在水中的极限电导率是由两种不同的离子运动机制控制的:(i)大块离子扩散和(ii)质子跳跃，也被称为“Grotthuss”机制和/或“原生转移”。这项工作报告了对室温以上测量的水溶液HCl, KOH和NaOH的极限电导率数据(Λ°)的关键评估。最初评估的数据集包括温度从273.15 K到873.15 K，水密度从1000 kg m - 3到270 kg m - 3，并减少到最终的严格评估数据集，温度在273.15到678.15 K之间，密度在346到1006 kg m - 3之间。结果被用来推导由于h30 +和OH -的原生转移引起的过量电导率的值，λE°，使用先前报道的水溶液KCl的相关性。推导了Λ°(HCl)、Λ°(KOH)、Λ°(NaOH)、Λ e°(h30 +)和Λ e°(OH−)水粘度与密度的简单经验相关性。利用Λ e°(OH−)相关性和先前报道的Λ°(NaCl)函数进行的测试表明，NaOH数据可以准确地再现到估计的不确定度范围内。所报道的相关性为更准确地模拟h30 +和OH−到超临界条件下的示踪剂扩散系数提供了一种方法。
{"title":"Critical Review of Transport Properties of HCl, KOH, and NaOH in High Temperature Water and Correlations for Transport Properties of H3O+ and OH−","authors":"H. Arcis, Christopher A. Lee, G. H. Zimmerman, P. Tremaine","doi":"10.1063/5.0138262","DOIUrl":"https://doi.org/10.1063/5.0138262","url":null,"abstract":"High-temperature tracer diffusion coefficients for H3O+ and OH− are important parameters in the modeling of diffusion-controlled reaction kinetics and mass transport processes under hydrothermal conditions, and these tracer diffusion coefficients are directly related to the ionic electrical conductivities in the limit of infinite dilution through the Nernst–Einstein relationship. The limiting conductivity of H3O+ and OH− in water is controlled by two separate mechanisms of ionic movement: (i) the bulk ionic diffusion and (ii) proton hopping, also known as “Grotthuss” mechanism and/or “prototropic transfer.” This work reports a critical assessment of the limiting electrical conductivity data (Λ°) for aqueous HCl, KOH, and NaOH measured above room temperature. The initial assessed dataset included temperatures from 273.15 K up to 873.15 K and water densities from 1000 kg m−3 down to 270 kg m−3 and was reduced down to a final critically evaluated dataset spanning temperatures between 273.15 and 678.15 K and densities between 346 and 1006 kg m−3. The results were used to derive values for the excess conductivity due to prototropic transfer, λE°, of H3O+ and OH− using correlations previously reported for aqueous KCl. Simple empirical correlations of water viscosity and density were derived for Λ°(HCl), Λ°(KOH), Λ°(NaOH), λE°(H3O+), and λE°(OH−). Tests using the λE°(OH−) correlation and a previously reported function for Λ°(NaCl) show that the NaOH data can be accurately reproduced to within the estimated uncertainties. The reported correlations provide a means to model more accurately the tracer diffusion coefficients for H3O+ and OH− to supercritical conditions.","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47451217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Marinković, R. McEachran, D. Fursa, I. Bray, H. Umer, F. Blanco, G. García, M. Brunger, L. Campbell, D. B. Jones
Results from the application of optical potential, relativistic optical potential, relativistic convergent close-coupling, and binary encounter Bethe models to electron scattering from gas-phase cadmium are presented. In particular, integral cross sections for elastic scattering, summed discrete electronic-state excitation, and ionization scattering processes are reported over an extended incident electron-energy range. Total cross sections are constructed by taking their sum. Measurements are presented for elastic scattering and for excitation to the 51P1 state. The theoretical and experimental results are compared to previous calculations and measurements. Recommended electron cross-section datasets are constructed over an incident electron energy range of 0.01–10 000 eV.
{"title":"Cross Sections for Electron Scattering from Cadmium: Theory and Experiment","authors":"B. Marinković, R. McEachran, D. Fursa, I. Bray, H. Umer, F. Blanco, G. García, M. Brunger, L. Campbell, D. B. Jones","doi":"10.1063/5.0145933","DOIUrl":"https://doi.org/10.1063/5.0145933","url":null,"abstract":"Results from the application of optical potential, relativistic optical potential, relativistic convergent close-coupling, and binary encounter Bethe models to electron scattering from gas-phase cadmium are presented. In particular, integral cross sections for elastic scattering, summed discrete electronic-state excitation, and ionization scattering processes are reported over an extended incident electron-energy range. Total cross sections are constructed by taking their sum. Measurements are presented for elastic scattering and for excitation to the 51P1 state. The theoretical and experimental results are compared to previous calculations and measurements. Recommended electron cross-section datasets are constructed over an incident electron energy range of 0.01–10 000 eV.","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2023-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42233470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The total partition sum, Q(T), and its first and second moments, Q′(T) and Q″(T), were determined in terms of the total internal partition sum, Qint(T), and the translational partition sum, Qtrans(T), for 14N2, 14N15N, and 15N2. The total internal partition sum was computed using term values determined using the molecular constants of Le Roy et al. [J. Chem. Phys. 125, 164310 (2006)] for the ground electronic state and molecular constants for the first eight excited electronic states. The work of Le Roy et al. provides the best term values available and, hence, the most accurate total internal partition sums and their first and second moments. The convergence of Qint(T) and its moments were carefully studied and resulted in values with small uncertainty to 9000 K. From these quantities, the isobaric heat capacity, the Helmholtz energy, the entropy, the enthalpy, the Gibbs function, and the JANAF functions S0, hef, and gef, were computed on a 1 K grid from 1 to 9000 K. The resulting thermodynamic quantities are the most accurately determined from the direct summation of Q(T), Q′(T) and Q″(T). These data are compared with literature values.
{"title":"Thermodynamic Functions for N2 from the Total Partition Sum and its Moments","authors":"R. Gamache, Nicholas G. Orphanos","doi":"10.1063/5.0137083","DOIUrl":"https://doi.org/10.1063/5.0137083","url":null,"abstract":"The total partition sum, Q(T), and its first and second moments, Q′(T) and Q″(T), were determined in terms of the total internal partition sum, Qint(T), and the translational partition sum, Qtrans(T), for 14N2, 14N15N, and 15N2. The total internal partition sum was computed using term values determined using the molecular constants of Le Roy et al. [J. Chem. Phys. 125, 164310 (2006)] for the ground electronic state and molecular constants for the first eight excited electronic states. The work of Le Roy et al. provides the best term values available and, hence, the most accurate total internal partition sums and their first and second moments. The convergence of Qint(T) and its moments were carefully studied and resulted in values with small uncertainty to 9000 K. From these quantities, the isobaric heat capacity, the Helmholtz energy, the entropy, the enthalpy, the Gibbs function, and the JANAF functions S0, hef, and gef, were computed on a 1 K grid from 1 to 9000 K. The resulting thermodynamic quantities are the most accurately determined from the direct summation of Q(T), Q′(T) and Q″(T). These data are compared with literature values.","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47132070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Surface tension values for 82 ethers have been compiled from databases, books, and papers in the literature. The data were carefully screened, and finally, 2122 values were selected. Each fluid dataset has been fitted with the Guggenheim–Katayama correlation with two, four, or six adjustable parameters, except diphenyl ether, for which the data taken from different sources clearly disagree. Thus, recommended correlations are proposed for 81 ethers. The proposed correlations provide mean absolute deviations equal to or below 0.5 mN/m and mean absolute percentage deviations below 2.6% for 79 ethers. Moreover, percentage deviations below 9.5% are obtained for all the selected data of 78 ethers. The highest deviations found are due to the disagreement between the data obtained from different sources and not to an inadequate mathematical form of the correlation model. These correlations are added to the collection of those previously proposed for different fluids, including common substances, alcohols, refrigerants, organic acids, n-alkanes, and esters.
{"title":"Recommended Correlations for the Surface Tension of Ethers","authors":"Á. Mulero, I. Cachadiña, A. Becerra","doi":"10.1063/5.0139446","DOIUrl":"https://doi.org/10.1063/5.0139446","url":null,"abstract":"Surface tension values for 82 ethers have been compiled from databases, books, and papers in the literature. The data were carefully screened, and finally, 2122 values were selected. Each fluid dataset has been fitted with the Guggenheim–Katayama correlation with two, four, or six adjustable parameters, except diphenyl ether, for which the data taken from different sources clearly disagree. Thus, recommended correlations are proposed for 81 ethers. The proposed correlations provide mean absolute deviations equal to or below 0.5 mN/m and mean absolute percentage deviations below 2.6% for 79 ethers. Moreover, percentage deviations below 9.5% are obtained for all the selected data of 78 ethers. The highest deviations found are due to the disagreement between the data obtained from different sources and not to an inadequate mathematical form of the correlation model. These correlations are added to the collection of those previously proposed for different fluids, including common substances, alcohols, refrigerants, organic acids, n-alkanes, and esters.","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43003669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, thermodynamic models based on the corresponding states framework with departure terms are developed for the refrigerant pairs R-32/1234yf, R-32/1234ze(E), R-1234ze(E)/227ea, R-1234yf/152a, and R-125/1234yf. These models are based on new measurements of density, speed of sound, and phase equilibria, combined with the data available in the literature. The model for R-32/1234yf is most comprehensive in its data coverage, with speed of sound deviations within 1%, density deviations within 0.1%, and bubble- and dew-point pressure deviations within 1%. The other mixtures have generally more limited data availability but a similar goodness of fit.
{"title":"Mixture Model for Refrigerant Pairs R-32/1234yf, R-32/1234ze(E), R-1234ze(E)/227ea, R-1234yf/152a, and R-125/1234yf","authors":"I. Bell","doi":"10.1063/5.0135368","DOIUrl":"https://doi.org/10.1063/5.0135368","url":null,"abstract":"In this work, thermodynamic models based on the corresponding states framework with departure terms are developed for the refrigerant pairs R-32/1234yf, R-32/1234ze(E), R-1234ze(E)/227ea, R-1234yf/152a, and R-125/1234yf. These models are based on new measurements of density, speed of sound, and phase equilibria, combined with the data available in the literature. The model for R-32/1234yf is most comprehensive in its data coverage, with speed of sound deviations within 1%, density deviations within 0.1%, and bubble- and dew-point pressure deviations within 1%. The other mixtures have generally more limited data availability but a similar goodness of fit.","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42379425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kehui Gao, Jiangtao Wu, I. Bell, A. Harvey, E. Lemmon
Fluid ammonia is highly associated because of strong intermolecular hydrogen bonding. This causes different behavior of thermophysical properties from nonpolar fluids, as reflected, for example, in the heat capacity. In this work, a new equation of state explicit in the Helmholtz energy with independent variables of temperature and density was developed, which includes a new associating term. Its uncertainties in density, vapor pressure, saturated liquid and vapor densities, and caloric properties were estimated by comparisons with experimental data. The new equation of state is valid from the triple-point temperature (195.49 K) to 725 K at pressures up to 1000 MPa and densities up to 53.13 mol dm−3. Physically correct behavior within the region of validity and at extremely high temperatures and pressures, and at temperatures far below the triple-point temperature, was obtained by applying constraints on various properties. The unique physical behavior of ammonia shown in some thermodynamic properties is described in detail, which will provide a preliminary template for developing equations of state for other associating fluids.
{"title":"A Reference Equation of State with an Associating Term for the Thermodynamic Properties of Ammonia","authors":"Kehui Gao, Jiangtao Wu, I. Bell, A. Harvey, E. Lemmon","doi":"10.1063/5.0128269","DOIUrl":"https://doi.org/10.1063/5.0128269","url":null,"abstract":"Fluid ammonia is highly associated because of strong intermolecular hydrogen bonding. This causes different behavior of thermophysical properties from nonpolar fluids, as reflected, for example, in the heat capacity. In this work, a new equation of state explicit in the Helmholtz energy with independent variables of temperature and density was developed, which includes a new associating term. Its uncertainties in density, vapor pressure, saturated liquid and vapor densities, and caloric properties were estimated by comparisons with experimental data. The new equation of state is valid from the triple-point temperature (195.49 K) to 725 K at pressures up to 1000 MPa and densities up to 53.13 mol dm−3. Physically correct behavior within the region of validity and at extremely high temperatures and pressures, and at temperatures far below the triple-point temperature, was obtained by applying constraints on various properties. The unique physical behavior of ammonia shown in some thermodynamic properties is described in detail, which will provide a preliminary template for developing equations of state for other associating fluids.","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42400321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This Review presents the state of knowledge of the thermophysical properties of water in all its phases and the reference formulations that provide standardized, recommended values of these properties for science and industry. The main focus is the standard formulations adopted by the International Association for the Properties of Water and Steam (IAPWS), but some properties are covered for which IAPWS has not yet adopted recommendations. It is emphasized that, despite many advances over the last 100 years, there is room for further improvement, and current weaknesses and opportunities for advancing knowledge are discussed. Particular attention is given to the formulation for thermodynamic properties of fluid water known as IAPWS-95, which is planned to be replaced in the coming years. Additional topics include properties of heavy water and seawater and the growing ability of molecular modeling to provide properties at conditions where experimental measurements are difficult or inaccurate.
{"title":"Improved and Always Improving: Reference Formulations for Thermophysical Properties of Water","authors":"A. Harvey, J. Hrubý, K. Meier","doi":"10.1063/5.0125524","DOIUrl":"https://doi.org/10.1063/5.0125524","url":null,"abstract":"This Review presents the state of knowledge of the thermophysical properties of water in all its phases and the reference formulations that provide standardized, recommended values of these properties for science and industry. The main focus is the standard formulations adopted by the International Association for the Properties of Water and Steam (IAPWS), but some properties are covered for which IAPWS has not yet adopted recommendations. It is emphasized that, despite many advances over the last 100 years, there is room for further improvement, and current weaknesses and opportunities for advancing knowledge are discussed. Particular attention is given to the formulation for thermodynamic properties of fluid water known as IAPWS-95, which is planned to be replaced in the coming years. Additional topics include properties of heavy water and seawater and the growing ability of molecular modeling to provide properties at conditions where experimental measurements are difficult or inaccurate.","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":"1 1","pages":""},"PeriodicalIF":4.3,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42103073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fufang Yang, Jingang Qu, G. Kontogeorgis, Jean-Charles de Hemptinne
A reference density database of aqueous alkali halide solutions is presented. The solutes are the 20 alkali halides consisting of the cations Li+, Na+, K+, Rb+, Cs+, and anions F−, Cl−, Br−, I−. Experimental density data of these aqueous electrolyte solutions are extensively collected and critically evaluated. A data evaluation procedure is proposed, utilizing support vector regression (SVR) to compare the experimental datasets against each other. Data evaluation is based on agreement with data from other sources rather than accuracy claimed in the literature. Datasets with large deviation from others are identified and removed. The proposed reference database consists of 11 081 data points of 586 datasets from 309 references. Maximum deviations between the selected datasets do not exceed 1%, and are smaller than 0.5% for most of the aqueous alkali halide solutions. SVR models are also trained based on the reference database. Data distribution is visualized using a Gaussian mixture model. Applicability domains of the SVR models are analyzed using Williams plots. An executable program is provided for calculations based on the SVR models.
{"title":"Reference Density Database for 20 Aqueous Alkali Halide Solutions","authors":"Fufang Yang, Jingang Qu, G. Kontogeorgis, Jean-Charles de Hemptinne","doi":"10.1063/5.0124173","DOIUrl":"https://doi.org/10.1063/5.0124173","url":null,"abstract":"A reference density database of aqueous alkali halide solutions is presented. The solutes are the 20 alkali halides consisting of the cations Li+, Na+, K+, Rb+, Cs+, and anions F−, Cl−, Br−, I−. Experimental density data of these aqueous electrolyte solutions are extensively collected and critically evaluated. A data evaluation procedure is proposed, utilizing support vector regression (SVR) to compare the experimental datasets against each other. Data evaluation is based on agreement with data from other sources rather than accuracy claimed in the literature. Datasets with large deviation from others are identified and removed. The proposed reference database consists of 11 081 data points of 586 datasets from 309 references. Maximum deviations between the selected datasets do not exceed 1%, and are smaller than 0.5% for most of the aqueous alkali halide solutions. SVR models are also trained based on the reference database. Data distribution is visualized using a Gaussian mixture model. Applicability domains of the SVR models are analyzed using Williams plots. An executable program is provided for calculations based on the SVR models.","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":"1 1","pages":""},"PeriodicalIF":4.3,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42200676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An empirical equation of state in terms of the Helmholtz energy is presented for n-octane. It is valid from the triple-point temperature 216.37 K to 650 K with a maximum pressure of 1000 MPa and allows for the calculation of all thermodynamic properties in the vapor and liquid phase, in the supercritical region, and in equilibrium states. In the homogeneous liquid phase, the uncertainty in density is 0.03% at atmospheric pressure. For pressures up to 200 MPa and temperatures between 270 and 440 K, density is described with an uncertainty of 0.1%. Outside this region, the uncertainty in the liquid phase increases to 0.5%. Densities in the vapor phase are estimated to be accurate within 0.5%. The uncertainty in vapor pressure depends on the temperature range and varies from 0.02% to 0.4%. Speed of sound in the liquid phase at temperatures below 500 K is described with an uncertainty of 0.1% or less. The isobaric heat capacity in the liquid phase can be calculated with an uncertainty of 0.1% and in the gas phase with 0.2%. A reasonable physical behavior of the equation of state was ensured by the analysis of numerous thermodynamic properties.
{"title":"A Fundamental Equation of State for the Calculation of Thermodynamic Properties of n-Octane","authors":"R. Beckmüller, R. Span, E. Lemmon, M. Thol","doi":"10.1063/5.0104661","DOIUrl":"https://doi.org/10.1063/5.0104661","url":null,"abstract":"An empirical equation of state in terms of the Helmholtz energy is presented for n-octane. It is valid from the triple-point temperature 216.37 K to 650 K with a maximum pressure of 1000 MPa and allows for the calculation of all thermodynamic properties in the vapor and liquid phase, in the supercritical region, and in equilibrium states. In the homogeneous liquid phase, the uncertainty in density is 0.03% at atmospheric pressure. For pressures up to 200 MPa and temperatures between 270 and 440 K, density is described with an uncertainty of 0.1%. Outside this region, the uncertainty in the liquid phase increases to 0.5%. Densities in the vapor phase are estimated to be accurate within 0.5%. The uncertainty in vapor pressure depends on the temperature range and varies from 0.02% to 0.4%. Speed of sound in the liquid phase at temperatures below 500 K is described with an uncertainty of 0.1% or less. The isobaric heat capacity in the liquid phase can be calculated with an uncertainty of 0.1% and in the gas phase with 0.2%. A reasonable physical behavior of the equation of state was ensured by the analysis of numerous thermodynamic properties.","PeriodicalId":16783,"journal":{"name":"Journal of Physical and Chemical Reference Data","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47571682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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