In the last video, I tried to kind of give you a sort of a big picture view of
the thermite reaction. And we talked about how the thermite
reaction was an analog for building a house.
It was a large scale process and when we have enough tools, we'll be able to
understand those large scale processes. Actually I'd like to maybe take an even
bigger picture of you and ask the question.
Why no thermodynamics? What's so useful about thermodynamics?
And I'll call this video, Benchmarking Thermoliteracy.
So, you're taking thermodynamics, right? And this is a course that enjoys a
certain reputation in higher education. So, if you remember your Dante, even
though I'm a chemist, I like to know a little something about classical
literature, you might be familiar with, lasciate ogne speranza, voi ch'entrate.
That's what inscribed over the gates of hell in Inferno, abandon hope all ye who
enter here. But, thermodynamics is worth studying,
even though it may be complicated, because it's such a powerful and useful
tool in chemistry, in physics, and all the physical sciences.
The first Nobel Prize in chemistry, in 1901, was awarded to Jacobus Henricus
van't Hoff, whose picture graces this slide.
And it was awarded for his contributions to understanding chemical equilibrium.
Some of you may actually recognize van't Hoff's name.
He's also quite well known for being the first to suggest tetrahedral carbon atoms
in organic chemistry. But his Nobel prize is for
thermodynamics. So, what's a thermodynamic principle that
you may even have encountered in prior work.
Here's an example of things that people will often look at in a course on
thermodynamics. Phase diagrams.
So, a phase diagram and the one that's showing here for carbon dioxide, tells
you, given a temperature, that's on the x axis, given a pressure shown on the y
axis, you can read across, and find within this diagram, what phase of matter
will carbon dioxide be. And so, if we pick a particular point
here, for instance, this is liquid carbon dioxide.
If we go down here to atmospheric pressure, which is about one bar, and we
go to a normal temperature. Our room temperature, which looks like
its right about here. It's a gas we know that.
It's one atmosphere. Carbon monoxide is a gas.
And then we know that it actually comes out as dry ice, as a solid.
It goes directly to the solid state when you get close enough.
This is all very interesting. But some people look at phase diagrams
and might say, yeah, I'm glad somebody knows that.
Ho-hum. However, understanding the phase diagram
for carbon dioxide is critical to actually using carbon dioxide for an
economically important process, and that is, dry cleaning.
So, it turns out that fluid carbon dioxide, whether as a liquid or a so
called supercritical fluid, and we'll learn a little bit more about
supercritical fluids in the not too distant future that fluid is useful for
removing dirt from clothing, for example. And the virtue of carbon dioxide as a
solvent in dry cleaning is that it can replace much less environmentally benign
fluids that would, otherwise, be used. Typically, say a chlorinated hydrocarbon
solvent. So, it was a chemist who actually
developed the use of fluid carbon dioxide for the dry cleaning process.
And actually we've got a picture of him here.
His name's Joe DeSimone. At the time that this picture was taken,
he was giving a talk at the University of Minnesota in 2003 and his affiliation
then was with the University of North Carolina.
And he was talking about CO2 technology, that is, how could you use knowledge of
supercritical or fluid CO2 in order to do a number of processes, with dry cleaning
being one of the most most economically important examples.
So, there's some thermodynamics in action in a very every day task.
I'd like to tell you another story about thermodynamics.
And in this case, I'm going to contrast that with a quote often attributed to PT
Barnum, most historians think it should actually go to someone named Hannum.
Maybe you know this quote, there's a sucker born every minute.
So, in 1979, there was an entrepreneur. His name was Joe Newman.
And, Mister Newman claimed to have invented an energy machine.
And in particular, the virtue of this machine was, no matter how much energy
you put in, you would get more energy out, you would create energy.
So, certainly this was something that was worth investing in.
It does turn out that the first law of thermodynamics, and we'll be discussing
the laws of thermodynamics, says, perpetual motion machines are not
allowed, which is another way of saying, you can't get more energy out than you
put in. And, the United States patent office
adopts a similar philosophy. So, in the 1980s, it turns out that
elected officials spent a lot of tax money trying to decide which of these two
mutually contradictory statements, I have a machine that creates more energy than
you put into it, or the first law of thermodynamics, could be true.
So, in 1911, the US Patent Office adopted a policy, and it says if you claim to
have patented a perpetual motion machine, you need actually to deposit it with the
patent office for at least a year. And they will look at it and if they
decide it is a perpetual motion machine, and they never have, then they'll give
you a patent. But Newman filed suit against the Patent
Office, and claimed that his energy machine wasn't really a perpetual motion
device, and so that regulation did not apply.