Improving Student Results in the Crystal Violet Chemical Kinetics Experiment

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• 作者：Nathanael Kazmierczak ; Douglas A. Vander Griend
• 刊名：Journal of Chemical Education
• 出版年：2017
• 出版时间：January 10, 2017
• 年：2017
• 卷：94
• 期：1
• 页码：61-66
• 全文大小：309K
• ISSN：1938-1328

文摘

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.