Best of the Week 2018-2019: Excellence in College Prep

EDSMEN MAKE SPARKS FLY IN MRS. LAVELLE'S CHEMISTRY LAB

Science department chair Mrs. Anne Marie Lavelle brought together her higher-level and standard-level IB Chemistry juniors and seniors to collaborate on a hands-on chemistry lab that made sparks fly. The lab itself was an overall review of formulas, reactions, oxidation and reduction, combustion, stoichiometry and reaction rates. The objective of this particular laboratory experiment was to find the empirical formula of iron oxide by combusting steel wool. Steel wool consists of fine iron fibers and a small percentage of carbon. The oxidation of iron can be studied by the combustion of these fine pieces of metal. The speed of oxidation of a metal (rusting) usually depends on its form. An ordinary piece of metal will not burn, however the fine fibers of the wool or a powder will ignite readily.

Students loosely attached approximately 0.800 grams of steel wool to a ring stand apparatus with a copper wire. By gently touching a 9-volt battery to the steel wool, the wool instantly ignited causing sparks to fly and oxidize the wool. Through rigorous analysis, students determined the theoretical mass of the oxide formed from each reaction, determined the empirical formula of the compound based on their data and brainstormed for changes that could be made to this experiment to improve future methods. However, students were warned that there were many possibilities of error throughout this experiment. Therefore, students wrote an error analysis of their formula and results.

"There were two separate reactions that could have taken place, or a bit of both, during this experiment," says Mrs. Lavelle. "Students were given the opportunity to control or at least discuss the control of the experiment's variables. Many of them got the wrong answer, but in science, we often fail and need to abide by the evidence and data. This was not as straightforward of a lab as they had wished for because it left room for problem-solving and technique building, but science is hard work and sometimes you will fail and that's okay. The scientific process requires us to rethink, think outside the box, modify the experiment and try again."