Improving Student Results in the Crystal Violet Chemical Kinetics Experiment
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[1] Calvin College
Calvin College
City of Grand Rapids, Estados Unidos
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- Localización: Journal of chemical education, ISSN 0021-9584, Vol. 94, Nº 1, 2017, págs. 61-66
- Idioma: inglés
- Texto completo no disponible (Saber más ...)
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Resumen
Despite widespread use in general chemistry laboratories, the crystal violet chemical kinetics experiment frequently suffers from erroneous student results. Student calculations for the reaction order in hydroxide often contain large asymmetric errors, pointing to the presence of systematic error. Through a combination of in silico synthetic data simulations and laboratory experimentation, we report on five potential sources of error: (1) the kinetic flooding approximation, (2) solution concentration mistakes, (3) signal processing, (4) spectrometer limitations, and (5) particulates in the solution. The majority of this asymmetric error can be eliminated by constraining the data collection region within spectrometer limitations, specifically 0.7–0.1 Abs for a SpectroVis+ spectrophotometer. The consistent detection of particulate formation during the later course of the reaction is an aspect of the reaction not previously explored. Guidelines for optimizing laboratory procedure, instruments, and software are provided.
