Experimento de recristalização: uma abordagem sobre ligações químicas utilizando o ciclo de Kolb no Ensino Médio

Abstract

Currently, the traditional chemistry teaching model, widely adopted in Brazilian high schools, hinders student learning because it is based on the reproduction of concepts and the memorization of abstract ideas. However, the experiment-based approach emerges as a teaching proposal that integrates theoretical and practical knowledge, making learning more dynamic and meaningful. This study aimed to evaluate the effectiveness of learning about chemical bonds among first-year high school students enrolled in a technical chemistry course through an experimental practice of recrystallization structured according to Kolb's Cycle. This cycle consists of four stages: concrete experience, reflective observation, conceptualization, and application. The activities were developed over three sessions and focused on the formation of ionic and covalent crystals, as well as the visualization of the crystal structures formed. The methodology began with the application of an initial questionnaire and an introductory discussion on chemical bonds using minerals provided by the school. Following the discussion, a theoretical lesson on Chemical Bonds was conducted. In the second session, the recrystallization experiment was carried out using copper sulfate, sodium chloride, potassium chloride, and salicylic acid. In the third session, the formed crystals were observed in the laboratory; subsequently, their crystal structures were presented to the class, and the final questionnaire was administered to conclude the session. The initial questionnaire revealed that 34.04% of the 43 students had a good understanding of chemical bonds. After applying the experimental methodology in the third session, it was found that 51% rated their knowledge as good or very good. The collected data demonstrated that the use of experimental practice contributed to an increased level of comprehension among the students regarding the content. Therefore, it can be concluded that the adopted teaching strategy was effective, contributing to a more dynamic understanding of the topic of chemical bonds.