The standard molar enthalpy of the base catalysed hydrolysis of methyl paraben revisited
| Autor: | Hermínio P. Diogo, Manuel E. Minas da Piedade, Miguel A. Rendas, Carlos E. S. Bernardes, M. Soledade C.S. Santos, Fernando Antunes, Rafael N. Bento, Valdir A.R. Semedo |
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| Rok vydání: | 2016 |
| Předmět: |
Isothermal microcalorimetry
chemistry.chemical_classification Standard enthalpy of reaction Base (chemistry) Chemistry Enthalpy Thermodynamics 02 engineering and technology Calorimetry 010402 general chemistry 021001 nanoscience & nanotechnology Kinetic energy 01 natural sciences Atomic and Molecular Physics and Optics 0104 chemical sciences Hydrolysis Thermochemistry Physical chemistry General Materials Science Physical and Theoretical Chemistry 0210 nano-technology |
| Zdroj: | The Journal of Chemical Thermodynamics. 103:176-180 |
| ISSN: | 0021-9614 |
| DOI: | 10.1016/j.jct.2016.07.042 |
| Popis: | The standard molar enthalpy of the base catalysed hydrolysis of methyl paraben, Δ r H m o , was obtained at 298.02 K, 303.04 K and 310.01 K. The determination relied on isothermal microcalorimetry measurements and on a thermochemical scheme that, in contrast with previous strategies, does not require kinetic information. The results obtained were Δ r H m o = −(50.99 ± 0.61) kJ·mol−1 at 298.02 K, Δ r H m o = −(50.60 ± 0.82) kJ·mol−1 at 303.04 K, and Δ r H m o = −(49.64 ± 0.90) kJ·mol−1 at 310.01 K. The Δ r H m o value at 298 K is in very good agreement with the previously recommended benchmark at this temperature. The current procedure allowed, however, a ∼7-fold improvement in precision. It was also found that the Δ r H m o values show a linear variation with temperature. The fact that this variation is small lends support to the previous assumption of a negligible temperature dependency of Δ r H m o around 298 K. The present work resolves some important discrepancies in the reported standard molar enthalpies of the base catalysed hydrolysis of methyl paraben. Such inconsistencies can have a considerable impact on the determination of the effective volume of flow-through calorimetric apparatus. This parameter is essential to obtain kinetic and thermodynamic information on the growth, metabolism, and adaptation of living cells from flow calorimetry experiments. |
| Databáze: | OpenAIRE |
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