Weekly Blog 9/22 through 9/29

This week, we started off with test prep for the first test on Wednesday. The first test was as hard as expected, and I suppose I didn't study enough for it. Those HotPots were a great way to study but they weren't enough to be able to do well on the test, as I now know. At least I know now how much I need to study in the future.

We were assigned new table groups and got new roles for pogils, as well. We tried them out later in the week. My role of recorder is actually a lot more difficult than I would have imagined, having to write and present the material. But, it forces me to learn so I like it.

After the test, we focused on Lewis models and Lewis structures in a pogil. These diagrams focus on how to represent the valence electrons of atoms and in turn how they bond with each other. They're also a good way to be able to see how atoms bond, and why some atoms are more easily bonded with than others. For example, the noble gases don't bond very often because of their full outer electron shell, and that is clearly shown in the diagrams. Here is a good link to how to make Lewis representations of atoms. It shows how to place the dots and how to label where bonding is ocurring. Lewis structures also are an application for electronegativity. The most electronegative atom will the in the center of the Lewis representation.

Lewis structures can be simple, but most are complex. It's mostly a problem of making sure there are the correct amount of valence electrons. I think I have the basic ideas down, but I could use some more practice, of course. I'm sure we'll be doing just that next week.

Weekly Blog 9/16 through 9/22

We began this week with a focus on limiting reactants and using stoichiometry to find which reactant was limiting the reaction. Limiting reactants seemed like it would be difficult before we actually learned how to do it. Stoichiometry seems to be very useful for a great amount of things with equations, in a simple way. Here is a great website for review of using stoich to limit reactants. We also did some practice particle diagrams to help us visualize the process of limiting reactants better rather than trying to look at cold numbers. 

To build off limiting reactants, we then learned how to use stoich to find the yield of reactions. Again, this seemed hard in theory but stoich made it very simple and easy to find the yield of reactions after you knew the limiting reactant. Yield is a simple concept and the only important thing about it is to find the limiting reactant in order to find theoretical yield.

This week was mostly practice with worksheets and whiteboarding, but we learned a lot. I feel like the whiteboarding is very useful because I get to see how everyone else does it and it also allows me to work with other people on problems, which helps me a great deal. There were no experiments this week, which is a bit of a disappointment as I love experiments. Oh well, there's always next week!

I'd say I have a solid understanding now of stoich and limiting reactants and finding yield. It's mostly just repurposing stoich to do different things, so once you have the base of it then you can do all the peripherals, I guess you could call them.

I don't have many pressing questions about this week except I do wonder what else can be done using stoichiometry. I'm sure we'll learn more about it next week or in the future. 

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.