Video 1.2 - Benchmarking Thermoliteracy

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Statistical Molecular Thermodynamics

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University of Minnesota

Statistical Molecular Thermodynamics

163 ratings

This introductory physical chemistry course examines the connections between molecular properties and the behavior of macroscopic chemical systems.

From the lesson

Module 1

This module includes philosophical observations on why it's valuable to have a broadly disseminated appreciation of thermodynamics, as well as some drive-by examples of thermodynamics in action, with the intent being to illustrate up front the practical utility of the science, and to provide students with an idea of precisely what they will indeed be able to do themselves upon completion of the course materials (e.g., predictions of pressure changes, temperature changes, and directions of spontaneous reactions). The other primary goal for this week is to summarize the quantized levels available to atoms and molecules in which energy can be stored. For those who have previously taken a course in elementary quantum mechanics, this will be a review. For others, there will be no requirement to follow precisely how the energy levels are derived--simply learning the final results that derive from quantum mechanics will inform our progress moving forward. Homework problems will provide you the opportunity to demonstrate mastery in the application of the above concepts.

Video 1.1 - That Thermite Reaction9:37

Video 1.2 - Benchmarking Thermoliteracy12:10

Video 1.3 - Quantization of Energy14:50

Video 1.4 - The Hydrogen Chloride Cannon12:18

Meet the Instructors

Dr. Christopher J. Cramer
Distinguished McKnight and University Teaching Professor of Chemistry and Chemical Physics
Chemistry

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.

A judge who was appointed to hear the case, Judge Thomas Penfield Jackson,

decided he did not have enough knowledge of thermodynamics himself.

So, he appointed a special master, a former commissioner of patents, William

Schuyler, to investigate the machine. And to the surprise of the court,

Schuyler's report came back and said, no question about it, Newman's energy

machine, it's fabulous. Output of energy is greater than input.

The judge was not entirely persuaded, so he taught himself a bit of Physics.

God bless. eight months later, he decided that

Schuyler's report had to be erroneous. And in support of his position, he cited

the laws of thermodynamics. So, those aren't laws on the statute

books, but they're pretty important laws. he advised that the National Institute of

Standards and Technology in the United States could look at the machine.

But Newman's attorneys refused. And media attention to the case led to a

United States member of Congress, Representative Bob Livingston, a

Republican from Louisiana, hearing media reports and deciding that Newman was

clearly being unfairly treated. An abuse of power by the patent office.

And together with six members of congress, he sought a private relief bill

that would force the patent office to issue a patent to Newman.

So, congress did what it does in the United States, it held hearings.

And an expert from the Nat-, National Bureau of Standards, that's what NIST was

called back in those days John Lyons, testified before the committee and he

said various things. But, fundamentally, it came down to, you

can't get more energy out than goes in, and that's the first law of

thermodynamics. Newman was next to testify, and

unperturbed by the NBS expert, he cited Schuyler's report and he did what a

salesman does. He sold the device to members of the

Senate panel. And one of the members of that panel was

Senator John Glenn, shown here in the in an astronaut's outfit.

Those of you who remember John Glenn will remember he was an astronaut.

Democrat from Ohio, brought a little bit or reason to the proceedings but not

actually as a physical scientist. And in particular, Senator Glenn asked

Newman if he had known William Schuyler before he'd been appointed by the court

as a special master. And Newman was a bit flustered and said

he thinks they met once before but it was unlikely Schuyler would remember that.

At which point, Glenn pointed out it was, in fact, Schuyler's patent law firm that

had represented Newman to the patent office for the original filing.

And at that point, all the senators began sliding back from the table, sound of

chairs sliding, and that's the end of this story.

So, it's a bit unfortunate from my perspective that these senators in the

United States Congress were mostly lawyers and not really swayed by a

violation of the First Law of Thermodynamics but they certainly did

understand conflict of interest and that's what ended this case.

Clearly more scientific literacy, if you will, thermodynamic literacy within

society at large would be a welcome contribution.

So, let me talk about my goals for this course and what I hope are your goals for

the course as well. Lets learn how the Universe really works,

and that is what thermodynamics does. It provides us a set of tools to make

predictions about how the Universe works. And I hope to provide you with some of

those tools. We won't have time to develop all of them

perhaps, but at least some fundamental and useful ones.

A subgoal is to end up smarter than most politicians, and of course, the more

difficult goal here admittedly at first, but that's enough snarkiness.

In this video, let me tell you about what the course is going to look like.

So, there will video lectures, just like these and for many of the lectures there

will be self assessments embedded within them.

And when you take these self assessments, you will be able to click on a little

button, explanation, that will tell you why the correct answer to the self

assessment is what is is and we'll see that in maybe two videos from now.

I will also have some additional demonstrations, so if you were drawn into

the course by that wonderful thermite reaction, hopefully there will be one or

two others that are equally as exciting. And there will be a few that maybe won't

necessarily explode or catch fire, but are still pretty interesting and

illustrate key thermodynamic concepts. So we'll solve those throughout the

course as well. Every week, at the end of the week, there

will be a homework assignment. And those will be available two weeks

ahead and one week past the individual week in question, after which, they'll be

graded. They're ten questions each, and each of

the questions is worth ten points, so each homework will be worth 100 points,

and there will be eight of them, one for each of the eight weeks when content will

be presented within the course. There will be a final exam at the end of

the course and that exam will be worth 200 points.

And passing in this course will constitute 60% or more of the possible

1,000 points. So, that's 600 points or more.

And that brings us to the end of the thermal literacy video as well as

explaining what the course is going to look like.

In the next lecture that we see, we're going to address a critical physical

phenomenon that's going to let us derive some of the tools that we're going to use

in computing thermochemical quantities. And that is the quantization of energy

that describes how energy is stored in microscopically small systems.

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