EXPERIMENTAÇÃO INVESTIGATIVA NO ENSINO DE QUÍMICA UTILIZANDO A ANÁLISE FÍSICO-QUÍMICA DA ÁGUA.

Abstract

The article examines the contribution of investigative experimentation to Chemistry teaching, focusing on the physicochemical analysis of water in a public school in the interior of Bahia, Brazil. Grounded in Ausubel’s Meaningful Learning Theory and Bardin’s Content Analysis, the study addresses critiques of prescriptive laboratory practices and advocates for contextualized, safe, and low-cost didactic sequences aligned with FUNASA manuals and Brazilian Ministry of Health regulations. Forty-one students participated, divided into two groups that collected samples from different taps, comparing water from the public supply with that stored in a polyethylene tank. Physical parameters (color, turbidity, temperature) and chemical parameters (total alkalinity, free CO₂, hardness, pH, residual chlorine, aluminum, fluoride) were analyzed. Given infrastructure and safety limitations, reagent strips and simplified procedures were prioritized without compromising pedagogical reliability. The physical results indicated that the initial whitish color in some taps resulted from air microbubbles caused by supply interruptions, not excess chlorine. Turbidity was low, and temperature showed slight variation, increasing in stored water due to solar exposure. Chemically, alkalinity ranged between 160–180 mg/L, pH was 8.5, no free CO₂ was detected, hardness was 150 mg/L, residual chlorine 2 mg/L, aluminum was absent, and fluoride was 1 mg/L — all within potability standards. Pedagogically, the activity fostered hypothesis formulation, collaborative work, critical data interpretation, and scientific communication. Student engagement increased as they connected experimental evidence with domestic experiences and public health, correcting misconceptions such as the automatic association between watercolor and chlorine. The study concludes that, even under logistical constraints, inquiry-based teaching enhances meaningful, replicable, and formative learning. By situating water analysis in students’ daily lives, the didactic sequence strengthened Chemistry concepts, promoted citizenship skills, and demonstrated the relevance of investigative approaches in Brazilian public schools.