Short Gas Chromatography Experiment That Richly Connects Thermodynamics to the Intermolecular Interactions That Govern Solute Retention
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Mark F. Vitha [1]
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[1] Drake University
Drake University
Township of Lee, Estados Unidos
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- Localización: Journal of chemical education, ISSN 0021-9584, Vol. 99, Nº 5, 2022, págs. 1923-1930
- Idioma: inglés
- Texto completo no disponible (Saber más ...)
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Resumen
This Article comes from a series of 2 h instrumental analysis laboratory experiments developed in response to social distancing requirements established because of the coronavirus pandemic (COVID). The experiments provided rich data-analysis opportunities that taught students the chemical principles that underpin instrumental techniques, yet made it possible to collect data in a relatively short period of time. This allowed more groups to cycle through the experiments in a given lab period while still maintaining social distancing. What follows focuses specifically on a gas chromatography experiment in which students measured the fundamental values of the standard free energy, enthalpy, and entropy of retention of a methylene unit using a homologous series of alkylbenzenes as the solutes. An analysis of student writing shows that students were able to connect the strength of intermolecular interactions governing retention with measured and calculated parameters such as retention time, retention factor, equilibrium constant, free energy, enthalpy, and entropy. They also demonstrated an understanding of how the instrument functions to allow the measurement of retention times, and how those retention times are converted into thermodynamic quantities. A brief description of the other experiments developed in response to COVID, with an invitation to contact the author for additional information, is included at the end of the Article.
