Article
Thermodynamics
Poonam Jangra Darolia, Sunita Malik, Manish Kumar, Dimple Sharma, Sapana Garg, V. K. Sharma
Summary: This study assessed the molar heat capacities, CP, of 1-methylpiperidine (1) + pyrrolidin-2-one (2) + pyridine, alpha-, beta-, gamma-picoline (3) mixtures at different temperatures and used these data to compute the excess molar heat capacities, C-P(E). The C-P(E) data were compared with the composition of the component molecules using the Redlich-Kister expansion and ternary adjustable parameters were calculated along with their standard deviations. The C-P(E) values were also verified using Graph theory. The results showed that the computed C-P(E) values were in good agreement with the measured data, suggesting the validity of the assumptions made in obtaining the C-P(E) data.
JOURNAL OF CHEMICAL THERMODYNAMICS
(2023)
Article
Physics, Multidisciplinary
Emil Roduner
Summary: In the absence of work, heat exchange in a sample corresponds to the change in internal energy, which includes kinetic energy of atoms/molecules, excitation of quantum states, and excess electron energy. Equilibrated samples can be described by Boltzmann's statistical thermodynamics and characterized by temperature T. Monotonic motion of stars in an expanding universe involves work against gravity and the exchange of kinetic and potential energy, but not heat. Heat and work are distinct properties in thermodynamic systems. For moving stars, temperature, pressure, and heat capacities are not properly defined, so applying thermodynamics is not advised. However, equilibrated atomic nanoclusters can exhibit negative heat capacities when kinetic energy is transformed into potential energy of expanding bonds.
Article
Thermodynamics
Poonam Jangra Darolia, Sunita Malik, Sapana Garg, Renu Chadha, Vinod Kumar Sharma
Summary: This study investigated the physical properties of binary mixtures of piperidine or 1-methylpiperidine + 2- or 3- or 4-picolines across a range of temperatures. The excess molar volumes, excess isentropic compressibilities, and excess heat capacities were analyzed and fitted to Redlich-Kister polynomial equations. Results showed that the values of Cp(E), VE, and κE(S) varied with different compositions, with noticeable trends observed for specific mixtures. Additionally, the applicability of Graph theory was tested, showing agreement between theoretical and experimental values.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2022)
Editorial Material
Chemistry, Physical
William E. Acree, Fleming Martinez
Summary: The recalculated partial molar volumes of the individual mixture components given in the authors' reply are thermodynamically inconsistent with the experimental excess molar volumes.
JOURNAL OF MOLECULAR LIQUIDS
(2021)
Article
Thermodynamics
Daniel Lozano-Martin, David Vega-Maza, Alejandro Moreau, M. Carmen Martin, Dirk Tuma, Jose J. Segovia
Summary: This study investigates the thermodynamic characterization of natural gas mixtures blended with hydrogen. The experimental data reveals the impact of hydrogen on properties such as speed of sound, heat capacity ratio, and molar heat capacity, compared with reference mixture models. Results show consistency within model uncertainty, with hydrogen-enriched mixtures approaching the limit of uncertainty at high pressures.
JOURNAL OF CHEMICAL THERMODYNAMICS
(2021)
Article
Thermodynamics
Sa Xue, Kun Hou, Yaohui Shi, Ziwen Zhang, Longhui Fang, Xiangyang Liu, Maogang He
Summary: This study measured the isobaric molar heat capacities of binary mixtures of dimethyl carbonate and n-alkanes. The results showed that dimethyl carbonate can significantly reduce the isobaric molar heat capacity, with the decrement increasing as the temperature and carbon numbers in n-alkanes increase. Pressure had no remarkable influence on the isobaric molar heat capacity.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2022)
Article
Spectroscopy
Qun-Chao Fan, Jun Jian, Zhi-Xiang Fan, Jia Fu, Hui-Dong Li, Jie Ma, Feng Xie
Summary: A new method is introduced for calculating the molar heat capacities of diatomic macroscopic gas based on a full set of microscopic molecular rovibrational energies. The method employs VAM, RKR, LEVEL program, and quantum statistical ensemble theory to calculate partition functions and molar heat capacities, showing excellent agreement with experimental values. This method offers an effective new approach to obtaining molecular rovibrational energies and molar heat capacities of macroscopic gas.
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
(2022)
Article
Chemistry, Physical
I. M. Abdulagatov, A. R. Bazaev, E. A. Bazaev, B. K. Osmanova
Summary: The critical behavior of a binary water+n-hexane mixture with fixed concentration of 0.5 mol fraction of n-hexane near the upper critical endpoint (UCEP) was closely studied, focusing on phase transition temperatures, pressure-temperature data, and equilibrium properties. Measurements were made for density, pressure, temperature, and concentration, with uncertainties estimated and excess molar volumes calculated for the mixture in the supercritical region. Additionally, virial coefficients were determined using low-density, high-temperature P rho T data.
JOURNAL OF MOLECULAR LIQUIDS
(2021)
Article
Chemistry, Physical
Maria-Luisa C. J. Moita, Luis C. S. Nobre, Angela F. S. Santos, Isabel M. S. Lampreia
Summary: Direct excess partial molar enthalpies of 2-(isopropylamino)ethanol in the water very-rich region and water in 2-(isopropylamino)ethanol rich-region were measured. The limiting excess partial molar values and enthalpies of molecular interactions between like molecules were obtained and compared with literature values for other amphiphiles. The results were interpreted in terms of molecular interactions supported by previous volumetric and compressibility studies.
JOURNAL OF MOLECULAR LIQUIDS
(2021)
Article
Thermodynamics
Daniel Lozano-Martin, Rodrigo Susial, Pedro Hernandez, Teresa E. Fernandez-Vicente, M. Carmen Martin, Jose J. Segovia
Summary: This work presents phase envelope and speed of sound data for two binary mixtures, comparing the experimental results with the calculated values from equation of state to verify the accuracy and reliability of the experimental data.
JOURNAL OF CHEMICAL THERMODYNAMICS
(2021)
Article
Chemistry, Physical
David A. Nicholson, Bin Jia, David J. Nesbitt
Summary: The study measured the heat capacity changes in DNA folding at the single-molecule level and the transition state, finding that the results were consistent with previous literature expectations.
JOURNAL OF PHYSICAL CHEMISTRY B
(2021)
Article
Chemistry, Physical
Hongqin Liu
Summary: This study extends the Carnahan-Starling (CS) equation of state method to propose a new equation for describing hard sphere and hard disk fluids, using the latest virial coefficients and compressibility data for verification and comparison. The research reveals that the simple new equations are as accurate as the Pade approximations, significantly improving the accuracy of the CS-type equation of state in the hard sphere case.
Article
Chemistry, Physical
Ziwen Zhang, Kun Hou, Sa Xue, Yang Zhou, Xiangyang Liu, Maogang He
Summary: In this study, the isobaric molar heat capacities of deep eutectic solvents consisting of choline chloride and triethylene glycol were investigated, and the correlation between them was established based on experimental data.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Chemistry, Physical
Neha Chaudhary, Anil Kumar Nain
Summary: In this study, physicochemical properties of binary mixtures of PEG 400 with benzyl methacrylate were evaluated using experimentally measured data. The excess properties were correlated with the Redlich-Kister polynomial equation to discuss intermolecular interactions. Theoretical mixing rules for correlating refractive indexes were assessed and compared with experimental data.
JOURNAL OF MOLECULAR LIQUIDS
(2021)
Article
Chemistry, Physical
Maria-Luisa C. J. Moita, Beatriz G. Fialho, Angela F. S. Santos, Isabel M. S. Lampreia
Summary: The polarity of binary mixtures of water and 2-(diethylamino)ethanol (DEEA) was investigated using solvatochromic dyes, and the preferential solvation model and multiparametric correlation analysis were applied to study the DEEA-solvent interactions.
JOURNAL OF MOLECULAR LIQUIDS
(2022)