P353: Thermoelectric material synthesis and characterization in upper-level laboratory classes

Author: Mary Elizabeth Anderson, Hope College, USA

Co-Author:

Date: 8/4/14

Time: 2:45 PM3:05 PM

Room: MAK B1120

Related Symposium: S34

Thermoelectric nanomaterial synthesis was incorporated in an upper-level inorganic laboratory, introducing students to solution-phase solid-state chemistry and material characterization techniques. Pre-lab lecture focused on alternative energy and necessary requirements for material implementation (i.e. high energy conversion, low production costs). Nanostructuring improves thermoelectric properties motivating the bottom-up modified polyol synthesis that the students conduct. Students gave literature presentations to gain an overview of methods and materials relevant in the field. Using CrystalMaker software, students were introduced to crystal structures and simulated x-ray patterns. This five week lab contains three different rounds of synthesis, beginning with a known target and advancing to investigate variables chosen by students. This project complimented research that focuses on understanding reaction pathways for the formation of PbTe and Bi2Te3. Products were characterized by powder X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Results were presented in a lab meeting and submitted in journal article format.

P147: Determining the chemical formula of unknown crystals as a semester-long inquiry theme for general chemistry lab

Author: Mary Elizabeth Anderson, Hope College, USA

Co-Author: Brent Krueger, Amanda Schuiling and Tod Gugino, Hope College, USA

Date: 8/4/14

Time: 11:10 AM11:30 AM

Room: MAN 123

Related Symposium: S8

Recently at Hope College, the general chemistry lab course was restructured to incorporate a theme of inquiry throughout the first semester. These changes were based on student feedback received through surveys administered at the end of the semester. Students now begin the lab by synthesizing unknown crystals (potassium ferric oxalate trihydrate) from provided unknown solutions A &B. These crystals are a striking green color with dramatic morphologies enthusing the students on day one. The students then spend the semester qualitatively and quantitatively analyzing the crystals to determine the chemical composition and formula for the complex compound. Students cycle between learning a lab skill and applying it to test their unknown crystals. Some of the techniques explored by students are as follows: qualitative analysis by flame test and by selective precipitation, titrimetric procedures, gravimetric analysis, and ion exchange chromatography. Presented here will be rationale for course revision and an overview describing how inquiry is structured within the course.