Thermodynamics Research Center / ThermoML | Thermochimica Acta

Thermodynamic investigation of several natural polyols (I): Heat capacities and thermodynamic properties of xylitol

Tong, B.[Bo], Tan, Z.-C.[Zhi-Cheng], Shi, Q.[Quan], Li, Y.-S.[Yan-Sheng], Yue, D.-T.[Dan-Ting], Wang, S.-X.[Shao-Xu]
Thermochim. Acta 2007, 457, 1-2, 20-26
ABSTRACT
The low-temperature heat capacity C0 p,m of xylitol was precisely measured in the temperature range from 80 to 390K by means of a small sample automated adiabatic calorimeter. A solid liquid phase transition was found from the experimental Cp T curve in the temperature range 360 375K with the peak heat capacity at 369.04 K. The dependence of heat capacity on the temperature was fitted to the following polynomial equations with least square method. In the temperature range of 80 360 K, C0 p,m(JK.1 mol.1) = 165.87 + 105.19x + 1.8011x2 . 41.445x3 . 41.851x4 + 65.152x5 + 66.744x6, x = [T (K) . 220]/140. In the temperature range of 370 390 K, C0 p,m(JK.1 mol.1) = 426.19 + 5.6366x, x = [T (K) . 380]/10. The molar enthalpy and entropy of this transition were determined to be 33.26+-0.17 kJ mol.1 and 90.12+-0.45 JK.1 mol.1, respectively. The standard thermodynamic functions (H0 T . H0 298.15) and (S0 T . S0 298.15), were derived from the heat capacity data in the temperature range of 80 to 390K with an interval of 5K. The standard molar enthalpy of combustion and the standard molar enthalpy of formation of the compound have been determined, AcH0m (C5H12O5, cr) = (.2463.2+-1.2) kJ mol.1and AfH0m (C5H12O5, cr) = (.1219.3+-0.3) 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 thermal stability of the compound. The results were in agreement with those obtained from heat capacity measurements.
Compounds
# Formula Name
1 CO2 carbon dioxide
2 H2O water
3 O2 oxygen
4 C5H12O5 xylitol
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 4
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal
  • Crystal
  • Liquid
  • Gas
  • DSC:UFactor:10
  • 1
  • POMD
  • 4
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal
  • Crystal
  • Liquid
  • Gas
  • ADIACA:UFactor:10
  • 1
  • POMD
  • 4
  • Triple point temperature, K ; Crystal
  • Crystal
  • Liquid
  • Gas
  • DTA:corrimp:UFactor:10
  • 1
  • POMD
  • 4
  • Triple point temperature, K ; Crystal
  • Crystal
  • Liquid
  • Gas
  • ADIACA:UFactor:10
  • 1
  • POMD
  • 4
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal
  • Temperature, K; Crystal
  • Pressure, kPa; Crystal
  • Crystal
  • VADIAC:UFactor:10
  • 85
  • POMD
  • 4
  • Molar heat capacity at constant pressure, J/K/mol ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • VADIAC:UFactor:10
  • 4
  • POMD
  • 4
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal
  • Temperature, K; Crystal
  • Pressure, kPa; Crystal
  • Crystal
  • VADIAC:UFactor:10
  • 58
  • POMD
  • 4
  • Molar heat capacity at constant pressure, J/K/mol ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • VADIAC:UFactor:10
  • 5
  • RXND
  • 4
  • 1
  • 2
  • 3
  • Molar internal energy of reaction at constant volume, kJ/mol
  • BOMBST:UFactor:100
  • 1