Methyl Red: A Chameleon That Reveals The Partition Between Two Phases As A Function Of pH. An Extraction Experiment

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 17 (2012) pp 163-165
DOI 10.1007/s00897122437

Methyl Red: A Chameleon That Reveals The Partition Between Two Phases As A Function Of pH. An Extraction Experiment

M. Jazmín Silvero, Fabio E. Malanca, Cesar G. Gómez, Juan C. Fraire and Gerardo A. Argüello*

INFIQC – Facultad de Ciencias Químicas – Universidad Nacional de Córdoba – Ciudad Universitaria – 5000 Córdoba, ARGENTINA, gerardoa@fcq.unc.edu.ar
Received April 26, 2012. Accepted July 14, 2012.

Published: 31 August 2012

Abstract. “A picture is worth a thousand words,” and besides it is easier to remember. This work is based on that premise, and its main objective is to show that creating a strong visual impact on the student’s mind is a useful tool to teach important chemistry concepts. The activities proposed involve a biphasic medium composed of an aqueous solution at different pH levels and petroleum ether (60–80°C), where an acid-basic indicator such as methyl red is employed to examine the phenomenon occurring in each phase, as it changes its color like a “chameleon.” During the process, students are introduced to core concepts of physical chemistry through a solvent partition system. The experiment is suitable for both qualitative and quantitative analyses of the extraction process.

Key Words: Laboratories and Demonstrations; quantitative analyses; equilibrium; acids/bases; laboratory instructions; physical properties

(*) Corresponding author. (E-mail: gerardoa@fcq.unc.edu.ar)

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