H 4 O 4 Na 2 ·1/2H 2 O, s). The low-temperature heat capacities of the title compounds over the temperature range of 78–379 K were measured by an automated adiabatic calorimeter. Thestandardmolarenthalpiesofcombustion of two compounds at 298
The combustion energy of thioproline was determined
by the precision rotating-bomb calorimeter at 298.15 K to be ΔcU= –2469.301.44 kJ mol–1.
From the results and other auxiliary quantities, the standard molar enthalpy
of combustion and the standard molar enthalpy of formation of thioproline
were calculated to be ΔcHmθC4H7NO2S,
(s), 298.15 K= –2469.921.44 kJ mol–1
and ΔfHmθC4H7NO2S, (s), 298.15K= –401.331.54
Authors:L. Peng, X. Jiangjun, M. Fangquan, L. Xi, and Z. Chaocan
The standard molar enthalpy of combustion of cholesterol was measured at constant volume. According to value of ΔrUmθ(−14358.4±20.65 kJ mol−1), ΔrHmθ(−14385.7 kJ mol−1) of combustion reaction and ΔfHmθ(2812.9 kJ mol−1) of cholesterol were obtained from the reaction equation. The enthalpy of combustion reaction of cholesterol was also estimated
by the average bond enthalpies. By design of a thermo-chemical recycle, the enthalpy of combustion of cholesterol were calculated
between 283.15∼373.15 K. Besides, molar enthalpy and entropy of fusion of cholesterol was obtained by DSC technique.
Authors:Y. Xu-Wu, Z. Hang-Guo, S. Wu-Juan, W. Xiao-Yan, and G. Sheng-Li
The copper(II) complex of 6-benzylaminopurine (6-BAP) has been prepared with dihydrated cupric chloride and 6-benzylaminopurine.
Infrared spectrum and thermal stabilities of the solid complex have been discussed. The constant-volume combustion energy,
ΔcU, has been determined as −12566.92±6.44 kJ mol−1 by a precise rotating-bomb calorimeter at 298.15 K. From the results and other auxiliary quantities, the standard molar enthalpy
of combustion, ΔcHmθ, and the standard molar of formation of the complex, ΔfHmθ, were calculated as −12558.24±6.44 and −842.50±6.47 kJ mol−1, respectively.
Authors:M. Ribeiro da Silva, C. Santos, M. Monte, and C. Sousa
MPa) molar enthalpies of formation, ΔfHm0, for
crystalline phthalimides: phthalimide, N-ethylphthalimide
and N-propylphthalimide were derived from
the standard molar enthalpies of combustion, in oxygen, at the temperature
298.15 K, measured by static bomb-combustion calorimetry, as, respectively,
– (318.01.7), – (350.12.7) and – (377.32.2)
kJ mol–1. The standard molar enthalpies of
sublimation, ΔcrgHm0, at T=298.15
K were derived by the Clausius-Clapeyron equation, from the temperature dependence
of the vapour pressures for phthalimide, as (106.91.2) kJ mol–1
and from high temperature Calvet microcalorimetry for phthalimide, N-ethylphthalimide and N-propylphthalimide
as, respectively, (106.31.3), (91.01.2) and (98.21.4)
The derived standard molar enthalpies of formation,
in the gaseous state, are analysed in terms of enthalpic increments and interpreted
in terms of molecular structure.
The low-temperature heat capacity Cp,m of erythritol (C4H10O4, CAS 149-32-6) was precisely measured in the temperature range from 80 to 410 K by means of a small sample automated adiabatic
calorimeter. A solid-liquid phase transition was found at T=390.254 K from the experimental Cp-T curve. The molar enthalpy and entropy of this transition were determined to be 37.92±0.19 kJ mol−1 and 97.17±0.49 J K−1 mol−1, respectively. The thermodynamic functions [HT-H298.15] and [ST-S298.15], were derived from the heat capacity data in the temperature range of 80 to 410 K with an interval of 5 K. The standard
molar enthalpy of combustion and the standard molar enthalpy of formation of the compound have been determined: ΔcHm0(C4H10O4, cr)= −2102.90±1.56 kJ mol−1 and ΔfHm0(C4H10O4, cr)= − 900.29±0.84 kJ mol−1, by means of a precision oxygen-bomb combustion calorimeter at T=298.15 K. DSC and TG measurements were performed to study the thermostability of the compound. The results were in agreement
with those obtained from heat capacity measurements.
Authors:J. Zhang, Z. Tan, Q. Meng, Q. Shi, B. Tong, and S. Wang
The heat capacities (Cp,m) of 2-amino-5-methylpyridine (AMP) were measured by a precision automated adiabatic calorimeter over the temperature range
from 80 to 398 K. A solid-liquid phase transition was found in the range from 336 to 351 K with the peak heat capacity at
350.426 K. The melting temperature (Tm), the molar enthalpy (ΔfusHm0), and the molar entropy (ΔfusSm0) of fusion were determined to be 350.431±0.018 K, 18.108 kJ mol−1 and 51.676 J K−1 mol−1, respectively. The mole fraction purity of the sample used was determined to be 0.99734 through the Van’t Hoff equation.
The thermodynamic functions (HT-H298.15 and ST-S298.15) were calculated. The molar energy of combustion and the standard molar enthalpy of combustion were determined, ΔUc(C6H8N2,cr)= −3500.15±1.51 kJ mol−1 and ΔcHm0 (C6H8N2,cr)= −3502.64±1.51 kJ mol−1, by means of a precision oxygen-bomb combustion calorimeter at T=298.15 K. The standard molar enthalpy of formation of the crystalline compound was derived, ΔrHm0 (C6H8N2,cr)= −1.74±0.57 kJ mol−1.
at T = 298.15 K, of 2-acetyl-5-nitrothiophene and 5-nitro-2-thiophenecarboxaldehyde as −(48.8 ± 1.6) and (4.4 ± 1.3) kJ mol−1, respectively. These values were derived from experimental thermodynamic parameters, namely, the standard (po = 0.1 MPa) molar enthalpies of formation, in the crystalline phase,
measured by rotating bomb combustion calorimetry, and from the standard molar enthalpies of sublimation, at T = 298.15 K, determined from the temperature–vapour pressure dependence, obtained by the Knudsen mass loss effusion method.
The results are interpreted in terms of enthalpic increments and the enthalpic contribution of the nitro group in the substituted
thiophene ring is compared with the same contribution in other structurally similar compounds.
Authors:Xue-Wei Han, Cai-Rong Zhou, and Xiao-Hua Shi
pure substance were determined by a precision oxygen bomb calorimeter. Then thestandardmolarenthalpiesofcombustion and formation were calculated by thermodynamics principle. So the related studies can provide a thermodynamic basis for taurine
Authors:Y. P. Liu, Y. Y. Di, W. Y. Dan, D. H. He, Y. X. Kong, and W. W. Yang
thermodynamic properties of (C 12 H 25 NH 3 ) 2 ZnCl 4 (s). Those researches were focused on crystal structure, solution thermodynamics, and phase transition. However, some basic thermochemical data such as thestandardmolarenthalpiesofcombustion and