Uso de indicadores naturais ácido-base do contexto amazônico no ensino de equilíbrio químico

This work was objective to investigate new natural acid-base indicators with potential application in experimental activities and in the context of the acid-base equilibrium. For this purpose, alcoholic and aqueous extracts from Buriti (Mauritia flexuosa), Camu-camu (Myrciaria dubia) fruits were tested and Dão (Ziziphus mauritiana) and leaves of the vegetable species sara-tudo (Justicia acuminatissima). The extracts were tested in HCl and NaOH solutions for the pH range 1 to 14, and as a context for teaching Chemistry, they were applied to products with acidic and basic characteristics present in our daily lives. The extracts of the camu-camu fruit and the leaves of sara-tudo showed the best acid-base indicators due to the greater distinction between colors at different pH values. Therefore, these extracts of acid-base indicators were used by students of the second series of regular high school, in experimental classes that addressed the content of acid-base equilibrium, and highlighted the importance of contextualizing the teaching of chemistry with their daily lives.