Well, this week I read from chapters 11, 12 and 13 on "Gases," "Liquids, Solids, and Intermolecular Forces" and "Solutions," respectively. It was all pretty straightforward (except for intermolecular forces, which make sense but are hard to keep track of); I enjoy this part of chemistry, especially the different states of matter. I think I also enjoy it because these are very tangible subjects for me. We see examples of gases, liquids and solids every day, and it's cool to see how these different substances are held together. What I've been discovering is, while the concepts are pretty easy, the homework in ALEKS can be very tricksy. I'll get an explanation for a problem, think "OK, that makes sense," go to start a new problem... and then they throw a whole new twist in it and I get stuck. Even if I have the concept right there will be one little conversion error somewhere that throws the whole thing off. Chemistry is definitely a precise science, and for good reason... it's just not so fun for the student on hour 3 of homework when you find you were off by one decimal place.
I was going to try making rock candy but it's been so humid the last few days that I gave it up as a lost cause. I'm going to give it a shot this week; my little brothers will love it. I do understand something about how it works; when the sugar liquid is heated it's able to hold more sugar than it would at room temperature. (I saw this demonstrated in an experiment earlier in the course.) As it cools, however, the solution becomes super saturated and the sugar begins to precipitate out. Put a string in and voila! If all goes the way it should, you have rock candy, courtesy of the principles of saturation that we learned about this week. I love it when chemistry relates to food. We used to subscribe to the magazine Cook's Illustrated and they often talked about the science they would use in their recipe development; almost all of it was chemistry-related.
Speaking of food, when I started thinking about it, I realized that most of the food we eat is in solution (maybe all, but I don't quite see how a hamburger is in solution... would that count as a solid solution?). Certainly nearly all the fluids we drink are solutions (except water, that's usually the solvent in the solution we drink). Even something like cold cereal is a solution; it's a solid in a liquid. I just had a glass of pear hard cider as I worked on my homework this afternoon, and that was an example of a gas solute in a liquid solvent. Solutions are everywhere in our food options!
The videos I found most helpful this week were in the solutions playlist. The first few were pretty commonsense material for me ( the two "Mass Percent" videos and "Molarity"). Given how tough the ALEKS homework can get, though, I was very appreciative to see basic straightforward examples in the "Dilution" video and the "Solution Chemistry" videos. Solution chemistry has been giving me a rough time in ALEKS so it's nice to have the videos as a reminder that the basic concepts are basic. It's just a matter of trying to break everything down and see where the missing links are.
I did two labs this week: the "Fountains, Oobleck and Gak-Slime" experiment and the experiment with vinegar and Alka-Seltzer. I had so much fun with the first experiment. I love mixing things together that turn into substances with absolutely no resemblance to their components. I think my favorite moment was trying to get my little brothers to play with the Oobleck. My youngest brother absolutely refused to touch it for quite awhile, but when he did I was ready with a camera. His face was pretty priceless.
"What IS this stuff? Eeeewwww!!!"
The Alka-Seltzer experiment proved to be an unexpected headache. First off, I didn't realize until AFTER the experiment that the store-brand Alka-Seltzer we had used was primarily for cold medicine. It seemed to work just fine until it came time to do the calculations. I was getting absolutely bizzare numbers and had to go back and re-do and adjust everything before I could do all the math for the final results. Then I started overthinking things and spent about an hour trying to figure out how to calculate the final mass of carbon dioxide, using these fancy conversions and calculations. Eventually, with my brain turning to gel, I realized "Oh. Subtract the final mass of the cup from the initial mass. DUH." At least I think I understand the principles behind the results, even if said results were funky.
And that was my week in chemistry! Crazy as always (I'm starting to resign myself to that) but interesting. Let's see what this next week will bring!
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