Turmeric and RGB analysis: A low-cost experiment for teaching acid-base equilibria at home

Abstract

An experimental approach to chemistry is a more meaningful way to learn than the use of textbooks alone. Working in the laboratory helps students understand basic concepts through their active engagement. Here, we present a series of inexpensive and environmentally friendly laboratory exercises on acid–base equilibrium. Their difficulty level is low, and they can be performed at home. Thus, they are especially suited for teaching in a social-distance context, such as during the COVID-19 pandemic. The experiments were designed to exemplify the main concepts of acid–base equilibrium, buffer capacity, and titration curves, using safe household reactants and no special equipment. RGB image analysis is used to detect pH variation and follow experiments’ progress. Titration of sodium carbonate with acetic acid using curcumin and red cabbage extracts as indicators is described. Our results show that curcumin extract is an excellent indicator for this purpose, and the end point is clearly observed through image analysis. These assays can be used and further adapted to teach students of different ages and socioeconomic backgrounds.