Sunday, July 13, 2008

Day 054: Enthalpy, entropy and (Gibbs free) energy

I thought I would take a break from studying and attempt to blog more. I really do apologize for not blogging as much because this really is the sole means of communication between us so I reiterate, sorry.

Our test tomorrow is math-heavy. A lot of formulas and concepts are tied together. I know them all, it's just a matter of sorting everything into its appropriate little box and then after that, fitting all the boxes together to make a pretty picture.

Just to give you an example (feel free and skip to the next paragraph in case this bores you) ... Enthalpy is the amount of heat given off (or taken) by a system.

Looks like everything is in proper disorder...

Entropy (the amount of disorder/disorganization within the system) relies on enthalpy -- the amount of heat tells us what kind of reaction it is and other cool tidbits. Gibbs Free Energy is a combination of enthalpy and entropy and it tells us how much energy is "free"/left over to do actual work (e.g., how gasoline works/is used in the piston of a car).

I know, it all sounds pretty dry and random but it's pretty cool how everything relates to one another. However, it is also a little overwhelming to have to keep all these concepts and deltaH, deltaS, and deltaG's straight. Much less the different kinds of deltaG. No worries though, I've got a handle on it, just wanted to keep you all in my chemical loop, haha.


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I feel like this applies:

The following is an actual question given on a University of Washington
engineering mid term. The
answer was so "profound" that the Professor shared it
with colleagues, which is why we now have the pleasure of enjoying it as

Bonus Question: Is Hell exothermic (gives off heat) or endothermic (absorbs

Most of the students wrote proofs of their beliefs using Boyle's Law, (gas
cools off when it expands and heats up when it is compressed) or some
variant. One student, however, wrote the following:

First, we need to know how the mass of Hell is changing in time. So we need
to know the rate that souls are moving into Hell and the rate they are
leaving. I think that we can safely assume that once a soul gets to Hell,
it will not leave. Therefore, no souls are leaving. As for how many souls
are entering Hell, lets look at the different religions that exist in the
world today. Some of these religions state that if you are not a member of
their religion, you will go to Hell. Since there are more than one of these
religions and since people do not belong to more than one religion, we can
project that all souls go to Hell.

With birth and death rates as they are, we can expect the number of souls in
Hell to increase exponentially.

Now, we look at the rate of change of the volume in Hell because Boyle's Law
states that in order for the
temperature and pressure in Hell to stay the same, the
volume of Hell has to expand as souls are added.

This gives two possibilities:

1. If Hell is expanding at a slower rate than the rate at which souls enter
Hell, then the temperature and pressure in Hell will increase until all Hell
breaks loose.

2. Of course, if Hell is expanding at a rate faster than the increase of
souls in Hell, then the temperature and pressure will drop until Hell
freezes over. So which is it? If we accept the postulate given to me by Ms.
Teresa Banyan during my Freshman year, "...that it will be a cold day in
Hell before I sleep with you, "and take into account the fact that I still
have not succeeded in having sexual relations with Ms. Banyan, then, #2
cannot be true, and thus I am sure that Hell is exothermic and will not

The student received the only "A" given.