From qualitative to quantitative: the use of factorial design in the study of dipyrone oxidation kinetics in chemistry classes

Abstract

Traditional chemistry teaching at the high school level often lacks contextualization, which hinders students understanding of how variables such as concentration and temperature interact in chemical kinetics. To mitigate this gap, this work reports a pedagogical intervention that converted a traditionally qualitative experimente, the oxidation of dipyrone by sodium hypochlorite (NaOCl), into a quantitative and modelable study. A factorial design was applied to simultaneously evaluate the effects of dipyrone concentration, bleach concentration, and temperature on reaction time. Unlike the traditional one-variable-at-a-time method, the experimental design identified complex interactions between factors, which were processed using the free software GNU Octave to generate response surfaces and contour plots. The results demonstrated that increasing temperature and dipyrone concentration accelerated the reaction by up to 40 seconds, while an anomalous retarding effect was observed for high bleach concentrations, likely due to pH variations and parallel reaction pathways. The use of statistical tools and mathematical modeling allowed students to transcend passive observation, promoting scientific literacy through an investigative approach. This methodology proved to be an accessible, low-cost, and robust strategy to integrate data science and experimental rigor into basic chemistry education