Week Two 9/16-9/22: Stoichiometry and Empirical Units

         This week, our main focus was on continuing to perfect our knowledge of stoichiometry. We worked through the worksheets of Stoich 3-8 either as a class with white boards or at home using the online lectures to guide us. By the end of the week, we also were introduced to the concepts of Empirical units and molecular formulas. These concepts were presented in class through a college level POGIL which we worked on together in groups and through two worksheets we did for homework.

         
          The beginning of the week started off primarily with review from the week prior, calculating the amount of grams in different substances using the Mole Ratio. As the week progressed, we began to learn newer concepts of stoichiometry such as the limiting reactant and the reactant in access in an equation. This concept was first explained to us using an analogy with car parts in a POGIL. The remaining tires would serve as the excess reactant whereas the one engine provided necessary to build the car served as the limiting reactant. The image below explains the concept in more depth.

          We applied this concept in class when we completed a worksheet dealing with reaction particles in different diagrams. We balanced the chemical equations and then built different molecules based on the reactants given and the products needed. This worksheet at least gave me a better understanding of what limiting and excess reactants really are. Stoich 7 then only strengthened our skills in solving for the limiting reactants in chemical equations with extra practice problems.

          

          From there, we learned a entirely new concept with Theoretical and Actual Yield. We learned that Theoretical Yield has to do with the maximum amount of product possible from the reactants given where Actual Yield has to do with the measured or actual amount of product from the reactants. Calculating the percentage yield, as seen in the formula below, is quite basic and did not take long for me to comprehend.

          Towards the end of the week, we began to learn about the empirical formula, empirical units, and the molecular formula. We were introduced to the concept in class but the first worksheet (Empirical Formulas 1) and corresponding lecture really helped me grasp the concept much better. The lecture for the worksheet can be seen in the link below. Our class then was given a worksheet over the weekend in which we learned how to calculate the molecular formula through an online lecture. 

http://www.screencast.com/t/xLskmyPz

          All in all, this week was almost fully based on learning the new concepts of stoichiometry with a little review here or there complemented by an introduction to the empirical formula. I believe my participation this week was better than last week in terms of contributing to our group's white board answers during our class discussions but I can always strive to be better. I still am slightly confused on how to get the empirical formula when trying to calculate the molecular molar mass but I'm guessing I may just need a bit more practice on those types of problems. Overall, I believe I have a very good understanding of the concepts we learned this week though.