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Indian Journal of Chemistry -Section A (IJC-A) >
IJC-A Vol.46A [2007] >
IJC-A Vol.46A(06) [June 2007] >
| Title: | Low-temperature heat capacity and standard molar enthalpy of formation of crystalline (S)–(+)–Ibuprofen (C₁₃H₁₈O₂)(s) |
| Authors: | Di, You-Ying
Ye, Chun-Tian
Tan, Zhi-Cheng
Zhang, Guo-Ding |
| Issue Date: | Jun-2007 |
| Publisher: | CSIR |
| Abstract: | Low-temperature heat capacities of the compound,(S)–(+)–Ibuprofen (C₁₃H₁₈O₂), have been measured by a precision automated adiabatic calorimeter in the temperature range
78 – 348 K. The experimental molar heat capacities in the temperature range 78 – 345 K have been fitted to a polynomial equation. The smoothed heat capacities and thermodynamic functions, (HT - H₂₉₈․₁₅ĸ) and (ST - S₂₉₈․₁₅ĸ), of the compound have been calculated by the heat-capacity polynomial equation. The constant-volume energy of combustion of the compound, has been found to be ΔUc (C₁₃H₁₈O₂, s) = – (7136.94 ± 4.74) kJmol⁻¹ by means of a home-made oxygen-bomb combustion calorimeter at
T = 298.15 ± 0.001 K. The standard molar enthalpy of combustion of the sample has been calculated to be ΔcHmº (C₁₃H₁₈O₂, s) =
– (7145.62 ± 4.74) kJmol⁻¹, from the constant-volume combustion energy. The standard molar enthalpy of formation of the compound has been derived, ΔքHmº (C₁₃H₁₈O₂, s) = – (542.48 ± 5.05) kJmol⁻¹, from the combination of the data of standard molar enthalpy of combustion of the compound with other auxiliary thermodynamic quantities through a Hess thermochemical cycle. |
| Page(s): | 947-951 |
| ISSN: | 0376-4710 |
| Source: | IJC-A Vol.46A(06) [June 2007]
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