Indicadores ácido e base: um ensino por investigação

Abstract

The cumulative and progressive teaching of scientific concepts, which does not consider the context in which these concepts were developed, can to explain difficulty in learning acid and base concepts. Many critics have been made to this form of approach of acid and base definition in many textbooks. Thus, the objective of this work is to understand the teaching process of the didactic sequence with an investigative approach to High School students, involving the discussion of definition and properties acid and base indicators. The didactic sequence was applied to two classrooms of High School. The data collection instruments used was based on students records, and Discursive Textual Analysis was used to understanding these records. The students have presented many difficulties to present their ideas, to provide solutions to the problem and to propose experiments, but we realized an evolution along the didactic sequence. The students recognized that: there are more efficient ways and safe to identify materials that the organoleptic properties, color change of an indicator is related to its way in the medium in question, a BrønstedLowry acid donates proton (H+) only if there is a basis to accept it, and improper disposal of certain materials can cause serious environmental problems. Keywords: Chemistry Education, Inquiry-based Science Education, Laboratory work in High School, Acid and base.