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Sean Rossiter '14
2012 Soar Student

Sean RossiterMajor/minor: Chemistry/German

Hometown: Warrington, Pa.

Project: Exploring the Use of the Dip Probe for in situ Spectroscopy

Project advisor: Dr. Carl Salter

Project details: The goal of this project was to continue and expand on a previous project on the ferric thiosulfate reaction while integrating and evaluating a new piece of equipment, the Ocean Optics dip probe. We also sought to develop a procedure to be used in a physical chemistry teaching lab that illustrated the effect of ionic strength on various chemical processes.

Why I wanted to participate in SOAR: The opportunity to immerse myself in a single lab project for an extended period of time was incredible, especially since I had just completed my freshman year.

Results: We observed two key effects of ionic strength on the reaction. The first part of the reaction, the formation of the complex, is suppressed by increased ionic strength. With more charge in solution, there is less electrostatic attraction between the positively charged iron ions and negatively charged thiosulfate ions. The opposite effect is found in the second part of the reaction, which requires two of the complexes, which are of like charge, to come together. This is consistent with a mechanism proposed in the literature. We also refined a previous SOAR project’s observation that the counter ion present has an effect on the decay of the complex. We determined that the iron thiosulfate complex, in the presence of a strong ligand like chloride, decays more quickly. This suggests that the counter ion is a part of the ferric thiosulfate complex. We’re also refining a procedure to be used in the physical chemistry lab.

Future plans: I’ve got a few years to go, but at this point I see myself in a graduate program or possibly medical school. I certainly hope to engage in undergraduate research next summer, perhaps at a program at another university.