 by Christa Colyer Department of Chemistry Wake Forest University Winston-Salem, North Carolina |
|
by Christa Colyer Department of Chemistry Wake Forest University Winston-Salem, North Carolina |
| Setting the Scene: | Eddy diffusion leads to peak broadening in chromatography due to the different lengths of time it takes solute molecules (of the same type) to travel through the column by way of different paths. |
| Casting: | A minimum of about 20 and a maximum of about 35 cast members are required for this scene. Six will be selected as solute molecules and the remainder will be stationary phase particles. |
| Action: | Stationary phase particles must appropriately arrange themselves across the front of the classroom so as to form a chromatographic column. Solute molecules will form two "zones" or "bands" of three members each (with each zone or band representing a different kind of solute or a different sample component). It must be clear that the three members of each zone are identical molecules. Although the three molecules in one solute zone will begin to "elute" or travel through the chromatographic column together, they will arrive at the other end at different times due to their different paths traveled through the stationary phase particles. Each zone of solute molecules will contain one molecule that travels through the chromatographic column as directly as possible, one molecule that travels through the chromatographic column with some detours, and one molecule that travels with many detours. After one zone of solute molecules has completely eluted, the other zone will similarly travel through the column, thus re-enacting travels similar to those of the first zone. |
Questions to consider before the scene (Act I):
1. Why is it important for the three solute molecules in each zone to be identical (even though the solute molecules between zones may differ)?
2. What physical aspect of a chromatographic column can lead to the existence of different routes or paths through that column?
Date Posted: 3/13/02 nas
