A Guided Inquiry Liquid/Liquid Extractions Laboratory for Introductory Organic Chemistry

A guided inquiry laboratory experiment for teaching liquid/liquid extractions to first semester undergraduate organic chemistry students is described. This laboratory is particularly useful for introductory students as the analytes that are separated are highly colored dye molecules. This allows students to track into which phase each analyte partitions and allows them to determine if they have successfully separated a mixture of two dyes. During the first part of this experiment, students determine how the partitioning of the various analytes changes as a function of the pH of the aqueous layer. They use these data to determine appropriate solvents for separating mixtures of dyes. After students have learned about the theory and practice of liquid/liquid extractions using dyes, they then separate and identify an unknown simulated cutting agent from a simulated drug. This experiment provides students with a better understanding of the theory and practice of liquid/liquid extractions, and, introduces them to a real-world application of this technique.