Heat capacities of 4-methyl-2-pentanone, 2,6-dimethyl-4-heptanone, 1-hexanol, 1-heptanol, and 1-octanol in the temperature range 298-318 K

1989 ◽  
Vol 54 (3) ◽  
pp. 602-607 ◽  
Author(s):  
František Veselý ◽  
Petr Barcal ◽  
Milan Zábranský ◽  
Václav Svoboda
Keyword(s):  
Heat Capacity ◽  
Liquid State ◽  
Constant Pressure ◽  
Heat Capacities ◽  
Temperature Range ◽  
Selection Of

Molar heat capacities of 4-methyl-2-pentanone and 2,6-dimethyl-4-heptanone in the liquid state have been measured at a constant pressure over the temperature range 298.15 to 318.15 K. In order that the appropriateness of selection of literature data for correlation of the heat capacity as a function of temperature may be verified, results for three 1-alkanols (1-hexanol, 1-heptanol, and 1-octanol) have been measured over the same temperature range.

SPECIFIC HEATS AND LATENT HEAT OF FUSION OF ICE

1930 ◽  
Vol 3 (3) ◽  
pp. 205-213 ◽  
Author(s):  
W. H. Barnes ◽  
O. Maass
Keyword(s):  
Heat Capacity ◽  
Latent Heat ◽  
Adiabatic Calorimeter ◽  
Heat Capacities ◽  
Heat Of Fusion ◽  
Final Temperature ◽  
Latent Heat Of Fusion ◽  
Temperature Range ◽  
Specific Heats

Values for the heat capacities of ice and resulting water from initial temperatures of between 0 °C. and − 78.5 °C. to a final temperature of + 25.00 °C. are measured to ± 0.05% or better with an improved adiabatic calorimeter previously described. The specific heats of ice over the temperature range 0° C. to − 80 °C. are found and the latent heat of fusion of ice at 0 °C. is obtained from these heat capacity determinations.

scholarly journals HEAT CAPACITY PROPERTIES OF AQUEOUS BUFFER SOLUTIONS OF L-HISTIDINE IN A WIDE TEMPERATURE RANGE

2019 ◽  
Vol 62 (11) ◽  
pp. 78-84
Author(s):  
Elena Yu. Tyunina ◽  
Anna A. Kuritsyna
Keyword(s):  
Heat Capacity ◽  
Amino Acid ◽  
Specific Heat ◽  
Sodium Phosphate ◽  
Heat Capacities ◽  
Buffer Solution ◽  
Partial Molar Heat Capacities ◽  
Aqueous Buffer ◽  
Temperature Range ◽  
Buffer Solutions

The influence of temperature and concentration of L-histidine on the heat capacity properties of its aqueous buffer solutions was studied by differential scanning calorimetry. The investigations were carried out in aqueous buffer solutions (pH 7.4) containing monobasic sodium phosphate and dibasic sodium phosphate, which brings the environment closer to the conditions of real biological systems. The pH values of the solutions were fixed with a digital pH meter Mettler Toledo, model Five-Easy (Switzerland). The differential scanning microcalorimeter SCAL-1 (Biopribor, Pushchino, Russia) was used for measure the specific heat capacity of the system under study. It was equipped with Peltier thermoelectric elements, two measuring glass cells with an internal volume of 0.377 cm3, as well as a computer terminal and software for calculating heat capacity. The standard error of measurement of the specific heat for the studied solutions was within ±7·10-3 J·K-1·g-1. The experimental values of the specific heat of solutions of the amino acid in a phosphate buffer solvent in the temperature range (283.15 – 343.15) K were obtained. The concentration of histidine was varied from (0.00215 to 0.03648) mol·kg-1. All the studied solutions were prepared by the gravimetric method using Sartorius-ME215S scales (with a weighing accuracy of 1·10-5 g). The apparent molar heat capacities of L-histidine in the buffer solution, as well as its partial molar heat capacities at infinite dilution, were determined. The calculated molar parameters increase with an increase in both temperature and amino acid concentration. It was shown that the partial molar heat capacities transfers of L-histidine from water to the buffer solution have positive values in the temperature range studied. The results are discussed on base of the Gurney model.

Apparent molar heat capacities and volumes of aqueous solutions of several 1:1 electrolytes at elevated temperatures

1986 ◽  
Vol 64 (5) ◽  
pp. 926-931 ◽  
Author(s):  
Preet P. S. Saluja ◽  
Jacques C. LeBlanc ◽  
Harold B. Hume
Keyword(s):  
Heat Capacity ◽  
Aqueous Solutions ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Constant Pressure ◽  
Solubility Limit ◽  
Heat Capacities ◽  
Apparent Molar Heat Capacities ◽  
Flow Microcalorimeter ◽  
Good Agreement

The results of heat capacity (Cp) and density (d) measurements at 0.6 MPa and in the temperature range 298.15–373.15 K are presented for several 1:1 electrolytes in water. The flow microcalorimeter and densimeter used for these measurements were modificatons of the room-temperature designs. Data were obtained over concentrations ranging from 0.02 to 1.0 mol kg−1 (or to the solubility limit, whichever was lower). The heat capacity of a solution relative to that of water was measured with a precision of ±0.1 mJ K−1 g−1 at all temperatures. The density of a solution relative to that of water was measured with a precision of ±5 μg cm−3. These Cp and d results were used to calculate the apparent molar heat capacities, [Formula: see text], and volumes, [Formula: see text], at 298.15, 323.15, 348.15, and 373.15 K, at a constant pressure of 0.6 MPa. These results are in good agreement with available literature data.

Molar heat capacities and enthalpies of fusion for the system zinc chloride-dimethyl sulphoxide

1987 ◽  
Vol 52 (9) ◽  
pp. 2188-2193
Author(s):  
Mojmír Skokánek ◽  
Ivo Sláma
Keyword(s):  
Heat Capacity ◽  
Phase Transitions ◽  
Temperature Dependence ◽  
Concentration Dependence ◽  
Zinc Chloride ◽  
Liquid State ◽  
Molar Heat Capacity ◽  
Heat Capacities ◽  
Dimethyl Sulphoxide ◽  
Molten State

Molar heat capacities and molar enthalpies of phase transitions in the system ZnCl2-DMSO have been investigated over the temperature range 240 to 405 K and the concentration range 11.1 to 40 mole % ZnCl2. The temperatures of fusion and of phase transitions were determined and compared with literature data. Equations were proposed for the description of the temperature dependence of the molar heat capacity in the liquid state. The concentration dependence of the molar heat capacity in the molten state was found to exhibit positive deviations from additivity.

scholarly journals Suitable model for the calculation of the correlation between the real and the average specific heat capacity and possibilities of its application

2013 ◽  
Vol 67 (3) ◽  
pp. 495-511
Author(s):  
Branko Pejovic ◽  
Ljubica Vasiljevic ◽  
Vladan Micic ◽  
Mitar Perusic
Keyword(s):  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Heat Capacities ◽  
Practical Significance ◽  
Suitable Model ◽  
The Real ◽  
Temperature Range ◽  
Specific Heat Capacities ◽  
Differential Properties

Starting from the definition of the average specific heat capacity for chosen temperature range, the analytic dependence between the real and the mean specific heat capacities is obtained using differential and integral calculation. The obtained relation in differential form for the defined temperature range allows for the problem to be solved directly, without any special restrictions on its use. Using the obtained relation, a general model in the form of a polynomial of arbitrary degree in the function of temperature was derived, which has more suitable and faster practical application and is more general in character than the existing model. New graphical method for solving the problem is obtained based on differential geometry and using the derived equation. This may also have practical significance since many problems in thermodynamics are solved analytically and graphically. This result was used in order to obtain the amount of specific heat exchanged using an analytical model or a planimetric method. In addition, this graphical solution was used for the construction of the diagram showing the dependence between the specific heat exchanged and temperature. This diagram also gives a simple graphical procedure for the calculation of the real and the average specific heat capacity for arbitrary temperature or temperature interval. The confirmation for all graphic constructions is obtained using the differential properties between thermodynamic units. In order for the graphical solutions presented to be applicable in practice, suitable ratio coefficients have been determined for all cases. Verification of the model presented, as well as the possibilities of its application, were given using several characteristic examples of semi-ideal and real gas. Apart from linear and non-linear functions in the form of polynomials, the exponential function of the dependence between specific heat capacities and temperature was also analysed in this process.

AB INITIO THERMODYNAMICS OF ZINC-BLENDE ZnS, ZnSe

2011 ◽  
Vol 25 (32) ◽  
pp. 4553-4561 ◽  
Author(s):  
HUAN-YOU WANG ◽  
HUI XU ◽  
JU-YING CAO ◽  
MING-JUN LI
Keyword(s):  
Experimental Data ◽  
Heat Capacity ◽  
Thermal Expansion ◽  
Constant Pressure ◽  
Local Density ◽  
Linear Thermal Expansion ◽  
Plane Wave Method ◽  
Temperature Range ◽  
Zinc Blende ◽  
Good Agreement

The density function perturbation theory (DFPT) is employed to study the linear thermal expansion and heat capacity at constant pressure (with the quasiharmonic approximation). The calculations are performed using a pseudopotential plane wave method and local density approximation for the exchange-correlation potential. The calculated results of linear thermal expansion coefficient and heat capacity at constant pressure for zinc-blende ZnS , ZnSe are compared with the available experimental data in a wide temperature range. Generally, in low-temperature range, they have good agreement. However, in high-temperature range, due to anharmonic effect and other reasons, lead to larger errors for these properties between the theoretical results and available experimental data.

Ideal–Gas Thermochemical Properties for Alkanolamine and Related Species Involved in Carbon Capture Applications

2020 ◽  
Author(s):  
Nayyereh hatefi ◽  
William Smith
Keyword(s):  
Heat Capacity ◽  
Electronic Structure ◽  
Co2 Capture ◽  
Carbon Capture ◽  
Ideal Gas ◽  
Thermochemical Properties ◽  
Temperature Range ◽  
Comparison Results ◽  
Electronic Structure Methods ◽  
Protonated Forms

<div>Ideal{gas thermochemical properties (enthalpy, entropy, Gibbs energy, and heat capacity, Cp) of 49 alkanolamines potentially suitable for CO2 capture applications and their carbamate and protonated forms were calculated using two high{order electronic structure methods, G4 and G3B3 (or G3//B3LYP). We also calculate for comparison results from the commonly used B3LYP/aug-cc-pVTZ method. This data is useful for the construction of molecular{based thermodynamic models of CO2 capture processes involving these species. The Cp data for each species over the temperature range 200 K{1500 K is presented as functions of temperature in the form of NASA seven-term polynomial expressions, permitting the set of thermochemical properties to be calculated over this temperature range. The accuracy of the G3B3 and G4 results is estimated to be 1 kcal/mol and the B3LYP/aug-cc-pVTZ results are of nferior quality..</div>

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