An integrated inquiry-guided approach laboratory experience to teach: Extraction, recrystallization and melting point determination

CHED 416

Ingrid Montes, imontes@uprrp.edu1, Johanna Fajardo, imontes@uprrp.edu1, and Linette M. Pruna, linettepruna@yahoo.com2. (1) Department of Chemistry, University of Puerto Rico, Rio Piedras Campus, P.O Box 23346, San Juan, PR 00931-3346, (2) Dept. of Chemistry, University of Puerto Rico, Río Piedras Campus, P.O. Box 23346, San Juan, PR 00931-3346
This presentation describes a straightforward experiment using the guided inquiry approach for the extraction and recrystallization techniques, which are very important since they are widely used in organic chemistry for purifying reaction products or isolating natural products. This experiment initially based on the extraction of a mixture of aspirin and acetaminophen extends the students' understanding of acid-base reactions of organic molecules and the relationship of these reactions to chemical structure. One of the goals addressed in this experiment is to explain, by the understanding of extraction- separation techniques for organic compounds, where in the gastrointestinal tract are analgesics absorbed? After conducting the extraction, the students recrystallize the solids and determine their purity by melting point. This approach allows students to integrate different concepts learned throughout the General Chemistry course in the context of organic chemistry. These concepts include pH, pka, density, and solubility. The results and limitations of this study will be presented.
 

Undergraduate Research Poster Session: Chemical Education
11:00 AM-1:00 PM, Monday, March 26, 2007 Hyatt Regency Chicago -- Riverside Center, Poster

Division of Chemical Education

The 233rd ACS National Meeting, Chicago, IL, March 25-29, 2007