ELABORACIÓN DE PAPEL INDICADOR A BASE DE EXTRACTOS NATURALES: UNA ALTERNATIVA FUNDAMENTADA EN EXPERIENCIAS DE LABORATORIO PARA EL APRENDIZAJE DEL CONCEPTO DE pH.

This article is framed by laboratory experiments directed from synthetic and illustrative flow charts, which promote a structured approach to the concept of pH, and their relation with the acid- base behavior and buffer solutions. To teach such concepts necessitated the development and standardization of three types of pH indicator paper as well as the use of natural substances such as red cabbage, red rose petals and the curry which are easily found in the market and present a chemical behavior that allows the consolidation of such structuring concepts. This aspect was evident in the subsequent application to a number of substances for everyday use, in several ranges of the pH scale, achieved from a collection of buffer solutions prepared in advanced by students. [ABSTRACT FROM AUTHOR]