Calculation of the Isobaric Heat Capacities of the Liquid and Solid Phase of Organic Compounds at and around 298.15 K Based on Their “True” Molecular Volume

A universally applicable method for the prediction of the isobaric heat capacities of the liquid and solid phase of molecules at 298.15 K is presented, derived from their “true” volume. The molecules’ “true” volume in A3 is calculated on the basis of their geometry-optimized structure and the Van-der-Waals radii of their constituting atoms by means of a fast numerical algorithm. Good linear correlations of the “true” volume of a large number of compounds encompassing all classes and sizes with their experimental liquid and solid heat capacities over a large range have been found, although noticeably distorted by intermolecular hydrogen-bond effects. To account for these effects, the total amount of 1303 compounds with known experimental liquid heat capacities has been subdivided into three subsets consisting of 1102 hydroxy-group-free compounds, 164 monoalcohols/monoacids, and 36 polyalcohols/polyacids. The standard deviations for Cp(liq,298) were 20.7 J/mol/K for the OH-free compunds, 22.91 J/mol/K for the monoalcohols/monoacids and 16.03 J/mol/K for the polyols/polyacids. Analogously, 797 compounds with known solid heat capacities have been separated into a subset of 555 OH-free compounds, 123 monoalcohols/monoacids and 119 polyols/polyacids. The standard deviations for Cp(sol,298) were calculated to 23.14 J/mol/K for the first, 21.62 J/mol/K for the second, and 19.75 J/mol/K for the last subset. A discussion of structural and intermolecular effects influencing the heat capacities as well as of some special classes, in particular hydrocarbons, ionic liquids, siloxanes and metallocenes, has been given. In addition, the present method has successfully been extended to enable the prediction of the temperature dependence of the solid and liquid heat capacities in the range between 250 and 350 K.

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Calculation of the Isobaric Heat Capacities of the Liquid and Solid Phase of Organic Compounds at 298.15K by Means of the Group-Additivity Method

Molecules ◽

10.3390/molecules25051147 ◽

2020 ◽

Vol 25 (5) ◽

pp. 1147

Author(s):

Rudolf Naef

Keyword(s):

Experimental Data ◽

Heat Capacity ◽

Goodness Of Fit ◽

Cross Validation ◽

Solid Phase ◽

Linear Equations ◽

Heat Capacities ◽

Molecular Volume ◽

Complementary Method ◽

Standard Deviations

The calculation of the isobaric heat capacities of the liquid and solid phase of molecules at 298.15 K is presented, applying a universal computer algorithm based on the atom-groups additivity method, using refined atom groups. The atom groups are defined as the molecules’ constituting atoms and their immediate neighbourhood. In addition, the hydroxy group of alcohols are further subdivided to take account of the different intermolecular interactions of primary, secondary, and tertiary alcohols. The evaluation of the groups’ contributions has been carried out by solving a matrix of simultaneous linear equations by means of the iterative Gauss–Seidel balancing calculus using experimental data from literature. Plausibility has been tested immediately after each fitting calculation using a 10-fold cross-validation procedure. For the heat capacity of liquids, the respective goodness of fit of the direct (r2) and the cross-validation calculations (q2) of 0.998 and 0.9975, and the respective standard deviations of 8.24 and 9.19 J/mol/K, together with a mean absolute percentage deviation (MAPD) of 2.66%, based on the experimental data of 1111 compounds, proves the excellent predictive applicability of the present method. The statistical values for the heat capacity of solids are only slightly inferior: for r2 and q2, the respective values are 0.9915 and 0.9874, the respective standard deviations are 12.21 and 14.23 J/mol/K, and the MAPD is 4.74%, based on 734 solids. The predicted heat capacities for a series of liquid and solid compounds have been directly compared to those received by a complementary method based on the "true" molecular volume and their deviations have been elucidated.

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Calculation of the Isobaric Heat Capacities of the Liquid and Solid Phase of Organic Compounds at 298.15K by Means of a Generally Applicable Computer Algorithm Based on the Group-Additivity Method

10.20944/preprints202002.0076.v1 ◽

2020 ◽

Author(s):

Rudolf Naef

Keyword(s):

Experimental Data ◽

Heat Capacity ◽

Goodness Of Fit ◽

Cross Validation ◽

Solid Phase ◽

Heat Capacities ◽

Computer Algorithm ◽

Molecular Volume ◽

Complementary Method ◽

Standard Deviations

The calculation of the isobaric heat capacities of the liquid and solid phase of molecules at 298.15 K is presented, applying a universal computer algorithm based on the atom-groups additivity method, using refined atom groups. The atom groups are defined as the molecules' constituting atoms and their immediate neighbourhood. In addition, the hydroxy group of alcohols are further subdivided to take account of the different intermolecular interactions of primary, secondary and tertiary alcohols. The evaluation of the groups' contributions has been carried out by means of a fast Gauss-Seidel fitting calculus using experimental data from literature. Plausibility has been tested immediately after each fitting calculation using a 10-fold cross-validation procedure. For the heat capacity of liquids, the respective goodness of fit of the direct (R2) and the cross-validation calculations (Q2) of 0.998 and 0.9975, and the respective standard deviations of 8.2 and 9.16 J/mol/K, together with a medium absolute percentage deviation (MAPD) of 2.69%, based on the experimental data of 1133 compounds, proves the excellent predictive applicability of the present method. The statistical values for the heat capacity of solids are only slightly inferior: for R2 and Q2, the respective values are 0.9915 and 0.9875, the respective standard deviations are 12.19 and 14.13 J/mol/K and the MAPD is 4.65%, based on 732 solids. The predicted heat capacities for a series of liquid and solid compounds has been directly compared to those received by a complementary method based on the "true" molecular volume [1] and their deviations elucidated.

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Heat capacities and enthalpies of fusion and transformation for solvates of some salts with dimethyl sulfoxide and dimethylformamide

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19883072 ◽

1988 ◽

Vol 53 (12) ◽

pp. 3072-3079

Author(s):

Mojmír Skokánek ◽

Ivo Sláma

Keyword(s):

Heat Capacity ◽

Phase Transformation ◽

Phase Transformations ◽

Dimethyl Sulfoxide ◽

Liquidus Temperature ◽

Molar Heat Capacity ◽

Solid Phase ◽

Zinc Nitrate ◽

Heat Capacities ◽

Liquid Phases

Molar heat capacities and molar enthalpies of fusion of the solvates Zn(NO3)2 . 2·24 DMSO, Zn(NO3)2 . 8·11 DMSO, Zn(NO3)2 . 6 DMSO, NaNO3 . 2·85 DMSO, and AgNO3 . DMF, where DMSO is dimethyl sulfoxide and DMF is dimethylformamide, have been determined over the temperature range 240 to 400 K. Endothermic peaks found for the zinc nitrate solvates below the liquidus temperature have been ascribed to solid phase transformations. The molar enthalpies of the solid phase transformations are close to 5 kJ mol-1 for all zinc nitrate solvates investigated. The dependence of the molar heat capacity on the temperature outside the phase transformation region can be described by a linear equation for both the solid and liquid phases.

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Group Contribution Methods for Estimation of Ionic Liquid Heat Capacities: Critical Evaluation and Extension

Chemical Engineering & Technology ◽

10.1002/ceat.201400667 ◽

2015 ◽

Vol 38 (4) ◽

pp. 632-644 ◽

Cited By ~ 17

Author(s):

Paul Nancarrow ◽

Moira Lewis ◽

Lamis AbouChacra

Keyword(s):

Ionic Liquid ◽

Critical Evaluation ◽

Heat Capacities ◽

Group Contribution ◽

Liquid Heat ◽

Group Contribution Methods

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MATHEMATICAL MODELING OF THE THERMODYNAMIC PROCESS GAS-STEAM BUBBLES

ACADEMIC JOURNAL Series Industrial Machine Building Civil Engineering ◽

10.26906/znp.2018.50.1079 ◽

2018 ◽

Vol 1 (50) ◽

pp. 220-226

Author(s):

B. А. Kutnyi ◽

А. М. Pavlenko

Keyword(s):

Gas Hydrates ◽

Solid Phase ◽

Thermodynamic Process ◽

Size Change ◽

Process Gas ◽

Exchange Processes ◽

Pressure Steam ◽

Liquid Heat ◽

Velocity Pressure ◽

Contact Liquid

A mathematical model that considers the inertial oscillations and thermodynamic components bubbles in liquid heat exchange processes, heat transfer on the boundary bubbles. Research of the dynamic characteristics of gas-steam bubbles in various size was conducted. After the calculations its temperature, velocity, pressure steam environment inside the bubble in time, graphs bubbles size change graphs were built . It is established that each bubble size has its oscillation frequency. Calculated speed phase transients and found that it is in its maximum during the bubble oscillation. For thermodynamic properties of the surface of contact liquid and gaseous phases defined amount of solid phase formed. The research results can be applied to optimize various of technological processes related to the boil, swelling materials, and the formation of gas hydrates in a fluid cavitation.

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Synthesis and properties of double gadolinium tellurites

Bulletin of the Karaganda University Chemistry series ◽

10.31489/2021ch3/67-73 ◽

2021 ◽

Vol 103 (3) ◽

pp. 67-73

Author(s):

A.A. Toibek ◽

◽

K.T. Rustembekov ◽

D.A. Kaikenov ◽

M. Stoev ◽

...

Keyword(s):

Phase Analysis ◽

Solid Phase ◽

Heat Capacities ◽

Ceramic Technology ◽

Phase Method ◽

X Ray Diffraction ◽

X Ray ◽

Cell Parameters ◽

Temperature Range ◽

Diffraction Patterns

For the first time, double gadolinium tellurites of the composition GdMIITeO4.5 (MII — Sr, Ba) were synthesized by the solid-phase method. The solid-phase synthesis of samples was carried out from decrepitated gadolinium (III) and tellurium (IV) oxides, strontium, and barium carbonates according to the standard ceramic technology. The synthesis was carried out in the temperature range of 800-1100 °C. The samples obtained were confirmed by X-ray phase analysis. X-ray phase analysis was carried out on an Empyrean instrument in the XRDML Pananalitical format. The intensity of the diffraction maxima was estimated on a 100-point scale. X-ray diffraction patterns indexing of the powder of gadolinium tellurites — alkaline earth metals studied were carried out by the homology method. The reliability and correctness of the results of indexing the X-ray diffraction patterns are confirmed by the good agreement between the experimental and calculated values of the interplanar distances (d) and the agreement between the values of the X-ray and pycnometric densities. It was found that compounds GdSrTeO4.5 and GdBaTeO4.5 crystallize in the monoclinic system and have the unit cell parameters, namely GdSrTeO4.5 — a = 12.7610, b = 10.4289, c = 8.6235 Å, V° = 1141.83 Å3, β = 95.77°, Z = 5, ρrent. = 3.22, ρpikn. = (3.10±0.09) g/cm3; GdBaTeO4.5 — a = 15.7272, b = 15.8351, c = 7.1393 Å, V° = 1769.72 Å3, β = 95.53°, Z = 8, ρrent = 3.71, ρpick = (3.61±0.10) g/cm3. Using the Landiya method, the standard heat capacities of the compounds were estimated from the calculated values of the standard entropies, and the temperature dependences of the heat capacities of the gadolinium tellurites synthesized were determined in the temperature range of 298–850 K.

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Gas Chromatographic-Chemiluminescence Method for Determination of Volatile NNitrosamines in Minced Fish-Meat and Surimi-Meat Frankfurters: Collaborative Study

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/73.6.947 ◽

1990 ◽

Vol 73 (6) ◽

pp. 947-952

Author(s):

John W Pensabene ◽

Walter Fiddler ◽

John G Phillips

Keyword(s):

Extraction Method ◽

Solid Phase ◽

Collaborative Study ◽

Energy Analyzer ◽

Chemiluminescence Method ◽

Fish Meat ◽

Relative Standard ◽

Minced Fish ◽

Standard Deviations

Abstract A collaborative study was carried out on a solid-phase extraction method for separating volatile N-nltrosamlnes, particularly N-nltrosodlmethylamlne (NDMA), from combination minced fish or surlml-meat frankfurters with detection by gas chromatography-chemllumlnescence (thermal energy analyzer). The results from the 10 collaborators were evaluated using the most recent AOAC guidelines for determining outliers and for the analysis of variance. For NDMA, repeatability standard deviations, sr, ranged from 0.56 to 2.25; repeatability relative standard deviations, RSDr, ranged from 8.9 to 11.5%. Reproducibility standard deviations, sR, for NDMA ranged from 1.40 to 6.49, and reproducibility relative standard deviations, RSDR, ranged from 24.2 to 28.9%. Our data compared favorably to the reproducibility (RSDR) curve of Horwltz. The method has been adopted official first action by AOAC.

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Heats of vaporization and gaseous heats of formation of some five- and six-membered ring alkenes

Canadian Journal of Chemistry ◽

10.1139/v79-368 ◽

1979 ◽

Vol 57 (17) ◽

pp. 2302-2304 ◽

Cited By ~ 18

Author(s):

Richard Fuchs ◽

L. Alan Peacock

Keyword(s):

Gas Chromatography ◽

Double Bond ◽

Heat Capacities ◽

Membered Ring ◽

Heats Of Formation ◽

Group Additivity ◽

Liquid Heat ◽

Heats Of Vaporization

The heats of vaporization of 1-methylcyclopentene, 3-methylcyclopentene, ethylidenecyclopentane, 1-ethylcyclopentene, methylenecyclohexane, allylcyclopentane, vinylcyclohexane, ethylidenecyclohexane, allylcyclohexane, 3,3-diethylpentane, 2,2,4,4-tetramethylpentane, and trans-2,2,5,5-tetramethyl-3-hexene have been measured by the gas chromatography – calorimetry method. These values have been combined with previously reported liquid heats of formation to give gaseous values of ΔHf. The results indicate that the internal double bond is favored by about 0.5 kcal over the exo in both 5- and 6-membered rings, but the endo–exo differences are much smaller than previously believed. Several of the liquid heat capacities that were measured were not well predicted by group additivity schemes.

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