Weekly Blog 9/9 through 9/13

We began the week learning a new concept, stoichiometry. Also called stoich, it is used to find the amount of reactants needed or used in a reaction, as well as the amount of a product that is produced in a reaction. An essential concept to stoich is the mole ratio. This we learned during the previous week and over the weekend, and is used as the "bridge" in the stoichiometry process. The mole ratio itself is very simple; it is the ratio of the amount of one element to an another in moles. To practice stoich and mole ratios, we did a worksheet for homework that had several problems for us to practice. Here is a link to wikipedia for a good review of stoichiometry.

We also spent a couple days preparing for our lab on Thursday. We first learned what a good and productive beginning question is, for example, "How does temperature affect the percent transmittance of a solution?" Later that night we copied the procedure into our lab books. Some of us learned the hard way while copying that you are always to put the divider after the page you are using, or else you'll write through 20 pages. During the lab, we put to use our knowledge of Molarity and calculated the concentration of Blue #1 in both Powerade Mountain Berry Blast and Gatorade G2 Glacier Freeze. After we calculated the concentration, we used a calibration curve obtained through a stock dye of known concentration and found the absorption rate of the Blue #1 in the drinks. Once we had the absorption rate, we could calculate the concentration of Blue#1 dye in both the drinks using Beer's Law, A=kC.

After doing the experiment and other practice worksheets I feel as though I have a good understanding of what we have covered this week and how to apply it to situations. The thing I need to work on most is probably stoichiometry, although I think I have a deep enough understanding of it to be able to do it well.

One question I still have regarding the lab is how the temperature effects the rate of absorption of the solution. I realize the physical problems involved with doing this, such as the solution could heat up or cool down the cuvette and cause it to warp slightly, changing readings. Also, the temperature could be inconsistent throughout the trials so that would be difficult to regulate. This question is still puzzling to me and I have been thinking about it throughout the week, so I decided to put in the blog.