Week 4&5 Reflection

        Over the past two weeks, our SG Chemistry 2 class discussed a variety of different concepts and ideas that expanded our knowledge of the subject. During the first week, we finished Unit 4 and took a test on the material. On Tuesday that week, we completed a worksheet on the expression of the ratio of the mass of certain elements to the total mass in a sample. This worksheet was simple to me, and I understood the concept right away. Later on, however, we got to a problem that was difficult for me to comprehend at first. We were given three compounds (A, B, and C) and each compound had a specific mass of nitrogen that combined with 1.00 grams of oxygen. After finding the ratio of nitrogen to oxygen for all three, I noticed right away that compound A had twice the amount of nitrogen as compound B, meaning that compound B had one particle of nitrogen and one particle of oxygen, whereas compound A had two particles of nitrogen and one particle of oxygen. The part that confused me was compound C, because its ratio of nitrogen to oxygen was half of compound B, which was stated as having a chemical formula of NO. If compound A had twice as many nitrogen particles than compound B, then would compound C have half a nitrogen particle? How could a compound have half a particle? After a class discussion of the worksheet, I was able to realize that compound C would not have half a nitrogen particle after all, but two oxygen particles instead. Having the discussion as a class was very helpful in this situation, and I was able to fully understand the entirety of the worksheet.
        The new couple days were dedicated to review. We worked on several worksheets in class to help us prepare and study for the test. Attached is a picture of the review guide we white boarded with our groups and then discussed as a class:

        After our test on Thursday, we had a small introduction of Unit 5 for the rest of the hour. Our class had to examine a large bag of styrofoam peanuts and see if we could come up with a way to determine the number of peanuts in the bag without counting. My immediate thought was to do some sort of volume calculation; maybe measure the length, width, and height of the bag to calculate its volume, then measure the length, width, and height of the peanut to find its volume, and then divide the volume of the bag by the volume of the peanut. Other people in the class seemed to have other ideas, however, mainly dealing with mass. We ended up deciding to find the mass of the whole bag and the mass of a peanut, and then dividing the mass of the bag by the mass of the peanut. I suppose that was an easier method than measuring the bag and peanuts and finding their volumes. In conclusion, our calculations told us that there were approximately 1500 peanuts in the bag. I was surprised and doubtful; by the looks of it, there seemed to be no more than 500 inside, max. Maybe this is how scientists felt when they discovered the atom; they must have been uncertain about their discoveries, but in the end, they just have to trust their data.
        On Friday, we began our exploration of relative mass through a container and hardware lab. My first thought when I heard the term "relative mass" was ratios of one mass to another. This would give the mass of one object in relation to another. For the lab, we started with four containers: one with 25 washers, one with 25 hex nuts, one with 25 bolts, and one with nothing inside. We then found the mass of each of the four containers and were able to find the mass of the 25 pieces by themselves by subtracting the mass of the empty container from the original mass of each. After finding these values, we had to answer the questions on the bottom in order to finish filling out the table. The questions were confusing to me; it was hard for me to logically try and figure out what exactly the questions were asking. In addition, it was often tricky to know when to subtract the weight of the container or the box, and when barrels came into the problems as well, it all became even more confusing. Discussing and white boarding the questions as a group helped me comprehend the problems more than when I was on my own, but they still proved to be difficult in my mind. Attached is a picture of my group's white board from this lab:

        The following Monday, our class continued the concept of relative mass by completing a POGIL activity. For the first part, we compared the ratio of the mass of chicken eggs to quail eggs, and found it to be 16:1. This first section was simple to me, and I understood the concepts of all the questions. By the beginning of the second part, I realized that we were learning about moles. I had never heard of a mole before, and I was slightly confused about what exactly they are. Then, I was told to think of a mole as I would think of a dozen; a dozen is a unit, and each dozen contains 12 objects. These objects can be anything, from a dozen tennis balls to a dozen pennies. Even though a dozen always consists of 12 items, the mass of the dozen can vary quite distinctly. This same characteristic applies to moles; just as a dozen pennies has a lower mass than a dozen tennis balls, a mole of carbon has a lower mass than, say, a mole of oxygen. Making this comparison significantly improved my understanding of moles, and has aided my comprehension of the worksheets and activities we have done since then in class.
        Over the next couple days in class, we worked on our empirical formula lab. The goal of this experiment was to react zinc with hydrochloric acid and come up with a chemical formula for the product, zinc chloride. The first thing we did was find the mass of our beaker and then the mass of our beaker with the zinc inside. Then, we subtracted the mass of the beaker from the mass of the beaker and zinc to find the mass of the zinc by itself, which would help us with later calculations. After reacting the zinc and hydrochloric acid together, we had to wait overnight to continue our experiment. Below is an image of our beaker while the contents were reacting:

The next day, we found that the substance left over in the beaker was solid and white, and covered the bottom of the glass. We then had to heat up the substance, zinc chloride, before we calculated the new mass of the beaker. At first, I wasn't sure why heating up the zinc chloride was necessary, but I soon found out that we needed to evaporate the left over hydrogen. Attached is an image of the heating process:

After heating the beaker twice and obtaining the same mass result each time, we were able to continue our calculations. To find the mass of the zinc chloride on its own, we subtracted the mass of the beaker we found earlier on. Then, to find the mass of the chlorine, we subtracted the mass of the zinc from the mass of the zinc chloride. Afterwards, we had to find the number of moles of both chlorine and zinc. I recalled that in order to convert from grams to moles, we had to multiple the grams by one mole over the molar mass of the substance. Using the periodic table, I was able to find the molar mass of both zinc and chlorine, and then used my conversion factors to calculate the number of moles each contained. My ending result was 0.055 moles of zinc and 0.11 moles of chlorine. The goal of the lab was to determine a chemical formula for zinc chloride, so my thinking was to compare the ratio of moles of zinc to moles of chlorine. Since 0.0055 moles : 0.11 moles is approximately 1:2, I was finally able to conclude that the chemical formula for zinc chloride is ZnCl2. Attached is our class data for the lab:

        Overall, the past two weeks of SG Chemistry 2 have been filled with significant concepts of the subject that will help guide us to a full understanding of the class as a whole.