The Determination of the Heat Capacities and the Heat Capacity Ratios of Gaseous Hydrogen Cyanide and of Hydrogen Sulfide1

1936 ◽  
Vol 58 (9) ◽  
pp. 1714-1717 ◽  
Author(s):  
W. A. Felsing ◽  
G. W. Drake
Keyword(s):  
Heat Capacity ◽  
Hydrogen Cyanide ◽  
Heat Capacities ◽  
Gaseous Hydrogen

scholarly journals Two Faces of the Two Phase Thermodynamic Model

2021 ◽  
Author(s):  
Ádám Madarász ◽  
Andrea Hamza ◽  
Dávid Ferenc ◽  
Imre Bakó
Keyword(s):  
Heat Capacity ◽  
Diffusion Coefficients ◽  
Heat Capacities ◽  
Water Model ◽  
Organic Liquids ◽  
Harmonic Model ◽  
Two Phase ◽  
Self Diffusion ◽  
Anharmonic Correction

<div>The quantum harmonic model and the two-phase thermodynamics method (2PT) are widely used to obtain quantum corrected properties such as isobaric heat capacities or molar entropies. 2PT heat capacities were calculated inconsistently in the literature. For water the classical heat capacity was also considered, but for organic liquids it was omitted. We reanalyzed the performance of different quantum corrections on the heat capacities of common organic solvents against experimental data. We have pointed out serious flaws in previous 2PT studies. The vibrational density of states was calculated incorrectly causing 39 \% relative error in diffusion coefficients and 45 \% error in the 2PT heat capacities. The wrong conversion of isobaric isochoric heat capacity also caused about 40 \% error but in the other direction. We have introduced the concept of anharmonic correction which is simply the deviation of the classical heat capacity from that of the harmonic oscillator model. This anharmonic contribution is around +30-40 J/mol/K for water depending on the water model and -8-10 J/mol/K for hydrocarbons and halocarbons. AC is unrealistically large, +40 J/K/mol for alcohols and amines indicating some deficiency of the OPLS force field. The accuracy of the computations was also assessed with the determination of the self-diffusion coefficients.<br></div>

scholarly journals Two Faces of the Two Phase Thermodynamic Model

2021 ◽  
Author(s):  
Ádám Madarász ◽  
Andrea Hamza ◽  
Dávid Ferenc ◽  
Imre Bakó
Keyword(s):  
Heat Capacity ◽  
Diffusion Coefficients ◽  
Heat Capacities ◽  
Water Model ◽  
Organic Liquids ◽  
Harmonic Model ◽  
Two Phase ◽  
Self Diffusion ◽  
Anharmonic Correction

The quantum harmonic model and the two-phase thermodynamics method (2PT) are widely used to obtain quantum corrected properties such as isobaric heat capacities or molar entropies. 2PT heat capacities were calculated inconsistently in the literature. For water the classical heat capacity was also considered, but for organic liquids it was omitted. We reanalyzed the performance of different quantum corrections on the heat capacities of common organic solvents against experimental data. We have pointed out serious flaws in previous 2PT studies. The vibrational density of states was calculated incorrectly causing 39 % relative error in diffusion coefficients and 45 % error in the 2PT heat capacities. The wrong conversion of isobaric isochoric heat capacity also caused about 40 % error but in the other direction. We have introduced the concept of anharmonic correction (AC) which is simply the deviation of the classical heat capacity from that of the harmonic oscillator model. This anharmonic contribution is around +30-40 J/mol/K for water depending on the water model and -8-10 J/mol/K for hydrocarbons and halocarbons. AC is unrealistically large, +40 J/K/mol for alcohols and amines indicating some deficiency of the OPLS force field. The accuracy of the computations was also assessed with the determination of the self-diffusion coefficients.

Equipment for the Experimental Determination of Thermal Properties of Fluids at Elevated Pressures

1972 ◽  
Vol 94 (4) ◽  
pp. 757-764 ◽  
Author(s):  
P. R. Bishnoi ◽  
D. B. Robinson
Keyword(s):  
Heat Capacity ◽  
Thermal Properties ◽  
Heat Exchanger ◽  
Experimental Determination ◽  
High Pressures ◽  
Heat Capacities ◽  
Compressible Fluids ◽  
Flow Calorimetry ◽  
Elevated Pressures

The available methods for determining the thermal properties of compressible fluids by flow calorimetry are reviewed and an analysis is given for the method of determining heat capacity ratios by passing the fluid at low and high pressures through a heat exchanger. The design of the heat exchanger calorimeter and its associated equipment are described in detail. The performance of the equipment in determining the heat capacities of nitrogen was evaluated at temperatures of 60.2, 75.7, and 150.4 deg C and at pressures up to 2200 psi. The results were compared where possible with those of other workers. Agreement was within about ±0.5 percent which is the anticipated accuracy of the method.

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

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.

An impregnated filter sampling approach for determination of hydrogen cyanide in air by a kinetic-fluorimetric micellar method

The Analyst ◽  
1999 ◽  
Vol 124 (4) ◽  
pp. 615-620 ◽  
Author(s):  
D. Sicilia ◽  
S. Rubio ◽  
D. Pérez-Bendito ◽  
N. Maniasso ◽  
E. A. G. Zagatto
Keyword(s):  
Hydrogen Cyanide ◽  
Sampling Approach ◽  
Filter Sampling

Correction-Determination of Hydrogen Cyanide in Air by Ion Chromatography

1985 ◽  
Vol 57 (6) ◽  
pp. 1168-1168
Author(s):  
T W. Dolzine ◽  
G G. Esposito ◽  
D S. Rinehart
Keyword(s):  
Ion Chromatography ◽  
Hydrogen Cyanide
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