Halloween celebrations on the chemical engineering front included, but were by no means limited to a two hour mass and energy balances prelim and the hardest physical chemistry problem set of the semester. I also had an essay to write and there was another problem set due for people taking Networks. All things considered, it was a fun night for the chemical engineers. Except not.
I had actually not procrastinated horribly since I knew that I’d have the prelim and then have to finish two assignments afterwards. I was almost done with the p-chem problem set and I’d started the essay earlier in the day. Yes, I wrote the entire essay the day before it was due . . . don’t tell my TA. As I mentioned recently, however, nothing gets done quickly in Mathematica.
So after a day of classes, giant tree broccoli (I had steamed broccoli at two different dining halls that day and both times the broccoli was the size of my palm.), intermittent essay writing, eigenfunctions, and last minute studying, I arrived at the mass and energy balances prelim with my pencil, calculator, note sheet, colored pens, colored pencils, and ruler. Besides the multiple choice questions, I didn't think it was horrible (I may change my mind when I get the graded prelim back). I spent way too much time arguing with myself about the multiple choice questions, then went to check the rest of the test with about half an hour remaining.
I was going through the third question when for some reason I thought I should check the chemical formula for butane, just to confirm I had it right. I turn to one of the data tables we’d been given and look up butane. C4H10. I look at my prelim. C3H8. Wait, what? My first thought: unprintable. My second thought: also unprintable. With twenty minutes to go, I had to rebalance my combustion reaction, then change pretty much every single number in the problem.
The icing on the cake is that I finished with a few minutes to spare, checked problem four, and I realized that all my units were wrong. Fortunately, I was working with ratios so the numbers didn't change, but there’s kind of a big different between 10 grams of a drug and 10 kilograms of a drug.
After all that, I got to go back to my dorm and finish my essay and wrangle some operators into commuting*. We were supposed to prove that the commutator between the x and y components (Lx and Ly) of the angular momentum operator was nonzero and equaled -ihLz. After expanding Lx and Ly, the book, and most internet sources would say something like “and after simplifying, this obviously equals -ihLz." Somehow, I don’t think that’s what my professor was going for. I finally found the technique I needed to fully expand the commutator into sixteen separate terms, fourteen of which I promptly crossed out because they equaled zero.
*Operators are rules that act on functions, like take the derivative of a function or multiply a function by three. If you have two operators named  and Ĉ acting on a function f(x), the commutator is the difference between doing Â, then Ĉ on f(x) and doing Ĉ, then  on f(x).
My Thursday night continued well into Friday morning. I think I got to sleep before my brother, but Chicago’s an hour behind Ithaca. Minor detail.
Overall, no treats on Halloween, but I insist that the first question on the mass and energy balances prelim was a trick. I didn't dress up for Halloween, but there was a discussion earlier in the week about me being an operator, because I wear a hat, just like operators. . . . Why yes, I do spend a lot of time with other ChemEs. Other costume ideas included being an equation sheet (for the mass and energy prelim) or a process unit. Hey, if we got the whole class to participate, we could reenact chemical processes. Who wants to be the condenser?
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