Produção de indicadores ácido-base naturais em solução e em papel a partir de extratos de plantas com pontencial aplicação no ensino de química

Abstract

A low-cost alternative to insert experimentation in Chemistry teaching is the use of natural acid-base indicators. In this perspective, the present work investigated the potential as an acid-base indicator, in solution and on paper, of extracts from the flowers of Allamanda blanchetii (Alamanda roxa), Delonix regia (Flamboyant), Begonia cucullata (Azedinha-do-brejo), Hippeastrum puniceum (Amaryllis), Asystasia gangetica (Coromandel) and Ixora coccinea (Ixora coral). For this, the collected species were weighed and then macerated, and the plant material of each species (20g) was immersed in 50 mL of 70% ethyl alcohol (%v) for a period of 72 hours to extract the pigments present in the flowers of the plants. plants The results obtained showed that both the alcoholic extracts and the pH papers, prepared from the species studied, proved to be effective in the identification of acids and bases, representing an alternative use for some of the traditionally used indicators. It is also emphasized that the property as an acid-base indicator of the species B. cucullata, H