Week 4 Blog Entry

This week in AP Chem, we went a little more in depth with Lewis structures, and completed a few lecture quizzes. We began the week with a POGIL on bond order and length and also did a few lecture quizzes to get some practice. However, the bulk of our week was spent discussing and performing our second lab.

We started off with an intro to the lab, in which we were trying to find out how much copper there is in a brass screw. We were given the reaction of copper and nitric acid, and spent an entire class period plowing through it to try and find the minimum amount of nitric acid we could use in the reaction. It involved some brushing up on stoichiometry, but as a class, we whiteboarded our process and all of us were able to understand the process fairly easily by then. It still catches me by surprise how much I have improved in stoichiometry when it used to be a grueling process for me just three weeks earlier. 

The next day, we came up with some beginning questions and began our experiment; we were trying to determine the relationship of the mass percent of copper in the Cu(NO3)2 and also the absorbance. We also tested two types of screws—a light screw and a slightly darker, heavier screw.

During the first day, we only had time to actually perform the reaction with our screw and the nitric acid. It was actually a really cool experience for me; after all, it was the first true reaction I witnessed in chemistry! I was just expecting some normal color change (like the many universal indicators I had used in the health and medicine magnet), but what happened was much more exciting. The nitric acid, which was a clear solution, was poured into our beaker containing the screw. Right away, the solution started bubbling and giving off a brown gas, which was toxic (all colored gases are considered toxic). As the screw was being dissolved, the solution began turning into a clear blue. The reaction went on for quite a while, and I could still see the remnants of some of the brown gas as I left class that day.

The day after, we tested the absorbance of our solution by diluting it with deionized water and testing it in the colorimeter. By the end of the class period I had gotten quite adept at the practice of using the bulb attached to a volumetric pipette to draw out solutions. We recorded our absorbance values on the board and in our lab journal.

At the end of the week, we finished off by introducing VSEPR models through the use of balloons which modeled our molecules.

It amazes me how quickly we are moving in AP chemistry, yet I don’t feel like I’m falling behind. Obviously, it is an extremely challenging class and I face difficult problems everyday, but I’m actually enjoying it. I am finding myself looking at the ingredients of my shampoo, or thinking about the compounds in my food, and I find myself thinking about where the energy of my food comes from (now I know it comes from breaking chemical bonds) and recognizing some compound names in places I would never suspect to find them. It is a truly engaging process for me. Truthfully, when I started the course, I didn’t really think I would enjoy chemistry. But I am learning new things everyday, and realizing how truly fascinating the world of chemistry is. It may sound cliché, but chemistry really is teaching me more about the world around me and how to interact with it. It can be stressful, but I feel like in the long run, chemistry will prove very rewarding for me.