Chemical Reactions in Science

We are well into our chemical reaction labs in science.  Last week an introductory lab allowed students to test a variety of unknown liquids with unknown white powders.  After recording observations of reactions or lack of reactions, they used their data to determine an unknown sample.  The purpose of the lab was to not only introduce reactions, but also focus on physical properties.

Yesterday we became "tardy" leprechauns (as St. Patrick's Day was a week ago) and turned pennies into "gold".  In reality, we learned about alloys. We first cleaned the pennies in Taco Bell sauce and through this inquiry learned that vinegar is an  ingredient in the sauce.  Relating this to the prior lab where we learned that acetic acid is vinegar, students quickly put it together that the acetic acid cleaned the penny.  When Lane asked why we didn't just clean them in vinegar I responded that this was more fun.  He replied, "Yes, and I now know taco sauce can clean pennies."  Next, we plated the pennies in zinc. Students really enjoyed seeing a silver looking penny.  Finally, we applied heat and allowed the copper and zinc to bond at the molecular level, creating brass.  This brass gave the pennies a "gold" appearance.

We have two more labs, a heat lab and a light stick lab coming up later this week, which will conclude our chemical reaction labs.  Astronomy will begin after the break.