This week's chapter of chemistry was fun! We learned about the ideal gas laws and the ideal gas equation. When I heard my professor lecture about it, I was completely freaked out. It looked like a bunch of equations to be memorized, without any rhyme or reason. (Nothing rhymes nicely when my professor speaks. His accent is a bit obnoxious.)
Then I finally got home and read the chapter, and by golly, it works! Joy!
Before continuing, I must note that my audience is composed of two groups: the pursuers of knowledge (ch"ch, as CA would say) and the ignoramuses (or theYoshvei Ohel , as the holy books call them). I can't write a post that will interest the former while being wholly understandable to the latter. I'd love to explain things well enough so that the yeshiva-educated can understand, but that would require more time than I have. So sorry, y'all! E-mail me, and I may be able to explain things further. Now back to business...
The first surprising thing was how proportions get transformed into equations. It's a neat trick. You can't do anything with a proportionality, but add in a constant, and viola! You've got a nifty equation.
While this trick was neat, it got kind of burdensome after we had transformed around four or five proportionalities into equations. There's Boyle's Law, and Avagadro's Law, and all the others that I can't remember. Each one got its equation that needed to be remembered. Plus I was a little perturbed that they never told us what these constants were. It seemed like cheating. Kind of like making calculations in moles, without knowingAvagadro's number.
But then they lumped all these equations into one mother of an equation: The Ideal Gas Equation. How many equations out there get a name with a word as nice and important-sounding as "ideal"? Not many, I bet. Anyhow, now that everything is compressed into one equation,PV = nRT , you only need one constant, R. It's one of the funniest constants I've ever encountered, with all those units tacked onto it. What is it? 0.082058 Moles Kelvin Atmospheres^-1 Liters^-1? Yeah, those are lot of units for one constant. But I'm glad that R has all those units.Cuz now I don't need to worry about them. I plug in the units, and friendly old Mr. R cancels all the units.
That's another nice thing about this equation: no messy conversions. A nice figure like 2.00 grams can become really ugly when those grams are actually 0.0991101396 moles of neon. But in ideal gases, the conversions are a breeze.Celisus to Kelvin? Just add 273! mL to L? C'mon, that just 1/1000! And you don't even need to bother with Torres to Atm . You just use a different value for R, and you're good to go! With my handy-dandy TI-83, I stored 0.082058 in the variable R, and 62.36396119 (i.e. the R value necessary for calculations involving Torres) in the variable Q. So all in all I dealt with normal numbers.
Now here's the real thing I like: Everything is so Goddamn linear! The algebra is a breeze. From PV = nRT, you can get V = nRT/P, T = PV/nR, or whatever. You only need to memorize one equation, and the others are derivable with the snap of the fingers! And because it's linear, you can estimate it all in your head. You can say things like, "Well, if it's 8 liters atSTP , it ought to still be in the neighborhood of 8 Liters with 770 Torres and 265 K. You can't make those estimations in other equations.
Last thing: The questions sound so bloody confusing--but they weren't. There are so many figures in each question. Here's an example: How many grams of N2 (g) at 25.0 degrees C and 734 Torr will occupy the same volume as 25.0 g O2 (g) at 30.0 degrees C and 755 Torr? If you got a molarity problems with this many numbers, you know you're heading into trouble. But with this, you just got to figure out your unknown variable, solve the equation for that variable, and then plug in your constants--and you can do the conversions while entering the stuff into thecalc! That's one of the most elegant things about mathematics: things which look scary turn out to be really simple. It's like transforming 3(X + 2)/6 = 6 into X = 10. Simplifying scary-looking expressions is what math's all about.
Now I just got to read the end of the chapter about kinetic-molecular theory and real gases. I don't know what that's about, but I saw variables getting squared and radical signs, so I fear things will not longer be so linearly predictable. Plus "real" sounds so ominous when contrasted with "ideal." And tomorrow we start the next chapter, which I haven't even looked at. So the horizon seems a bit cloudy, but at least I'll share the jubilation with you as long as it lasts.