Physical Chemistry – PChem4all

Education, Philosophy, Physical Chemistry, Spectroscopy

Why Do I Love Pchem?

Posted on November 22, 2017November 22, 2017 by D. L. Williams

Pchem, how do I love thee?
Let me count the ways…

1. Pchem connects abstract concepts to concrete reality.

The concept of the wave nature of light and matter is very abstract. It is not directly measurable. But the mathematics of interacting waves allows us to predict the interactions of light and matter. This is called spectroscopy.

Your eyes are pigment-based spectrometers detecting light at different wavelengths giving you the ability to perceive what we call color.

From these abstract wave equations we get concrete products like laser pointers and digital cameras. And I love it!

2. Pchem simulates natural phenomena well.

Some of the spectroscopic simulations I have seen in pchem have been truly amazing. To appreciate this, one may need a micro-course in statistics.

The R² value can be thought of as “how much scatter in the data is explained by your model”.

A decent calibration curve in an environmental lab or water quality lab will have a 99.95% R² value, meaning that the calibration model captures 99.95% of the scatter in the data.

The R² value for modeling the rotational-vibrational spectroscopic transitions in carbon monoxide is often 99.9996% or better. This means our pchem model for molecular vibration and rotation is capable of capturing over 99.999% of the variation in the data. That’s crazy-good! In fact, this model is so detailed, we can tell how much the CO bond length stretches as it spins faster and faster. I love that!

3. Pchem transforms your imagination.

OK. So the wave function concept allows us to simulate nature and to produce exciting gadgets. But what IS the wave function, ontologically?

This is perhaps the most exciting thing about pchem. It transforms your imagination. I am drawn to think deeply about the wave nature of matter, the balance of Coulombic attraction and repulsion, the coupling of intrinsic angular momentum.

What IS the angular momentum of a WAVE?

Where IS the mass in a WAVE?

What (or WHO) sustains these never-decaying ground state wave functions?

Amazing questions for an amazing life of the mind, which is another reason I love pchem.

How to Teach Yourself

Posted on September 3, 2014 by D. L. Williams

How do you teach yourself a new skill? How do you learn a tough subject? (like pchem?) I’m glad you asked. Here are my tips and tricks specifically focused on pchem survival (but applicable to life in general).

1. Don’t be afraid! (and that’s an order!)

Thousands have been down this road and they were in your shoes back then. You may have to shore up some mathematical deficiencies and look up some vocabulary, but these tasks are obvious to you as you go along. None of this affects your value as a person. But do you have the drive to re-learn what you have forgotten and dig into what you don’t know yet? Decide now! This is not a technical question. It is a heart question. Your answer to this question will determine your future as a productive team member after graduation.

2. Do the tutorials.

Every book has example problems in the text. Every coding site has tutorials. Even Excel has example data sets in its help files to show you “how it is done”. Do the tutorials.

3. Read the text with a pencil NOT a highlighter.

Write in your book margins. Rework math proofs in your problems notebook. Unless the material goes in your eyes, rattles around in your brain, filters down your arm, and out through your pencil, then you haven’t comprehended the material. Highlighting is nothing but self-deceptive Arts and Crafts.

4. Keep a problems notebook.

Do all your problems in a composition book. It is bound and sturdy. It will last much longer than a spiral notebook. Thirty years from now, you can be amazed at how bad-a$$ you were in college when you look at the math problems you did!

AND you can use it to shame your college-aged kids when they complain that their college prof won’t just upload the homework concepts directly into their brain-chip.

5. UNITS!

If you would just use UNITS on your numbers you would catch 99% of your errors. I can’t scream this loudly enough! Units, units, UNITS! Use them, or fail. It’s on you.

“But they take up space. They take time. Whaa Whaa Whaaaa” Look at the photo uploaded with this post. There is NO way to catch all the powers of 10 that jump around in that problem without using units.

6. Pro-tip: Be Disciplined

“The scheduled task gets done”, said my father.

If your homework time is not scheduled, then it will not get done. If you are not using the phrase, “I can’t, I have PHCEM homework to do.” Then you are not learning pchem.

If you want to learn piano or guitar and you don’t schedule practice time, then I don’t want to hear you play. It is the same with sports. If you don’t schedule practices, then I’m not buying a ticket to your game.

Put LEARNING on the calendar, not just TESTING.

—Here endeth the lesson.

Spectroscopy

Excel Roller Coaster – Yes, my hobby is Excel

Posted on August 29, 2014 by D. L. Williams

If you have FUN programming Excel, on a SATURDAY…You MIGHT be ~~a Redneck~~ I mean, you might be a PCHEMIST.

Years ago, I was at home on a Saturday fiddling with a wave function problem in Excel. The plot on the screen was of a couple of cosines, and my 8-year-old son said, “Hey that looks like a roller coaster”.

“It sure does.” I said. “Do you want to make a roller coaster in Excel?”

“Yes!”, he said.

So over the next four hours we had some quality father son time making a roller coaster in Excel. He learned something about cosine functions, and how to put custom backgrounds on a chart. Some of the finer details he did not care much for were anchoring cells, negative error bars, or the mod() function. But he really appreciated the custom look of a white wooden roller coaster and the looping macro that made the coaster run along the track.

You can download the macro-enabled (.xlsm) workbook file from my curiosities page to see how these functions and settings were used. Here is a time-lapse video of my creating the page from scratch. There are some fun tricks so I hope you enjoy it. the background loop is a bit annoying. Sorry.

The coaster uses an infinite loop. To kill it just click Ctrl+Break, and it will stop.

What Excel awesomeness to you have to share? What questions do you have about these functions and settings in this fun application?

Ask in the comments field, and subscribe for more fun in the future (like my Sudoku solving spreadsheet).

Spectroscopy

Fall Cleaning

Posted on August 26, 2014August 26, 2014 by D. L. Williams

Forget Spring. I just purchased a lot of optics, and before I rip them from their protective packaging, I had better review my handling and cleaning techniques.

Fortunately for me, Edmund Optics – the company that sold said optics – is savvy enough to send an email approximately 2 weeks after my purchase with guidelines and reminders about how to care for my optics. Here is their first paragraph followed by a link to the rest of their article. (This is not a sole endorsement of EO, but it is an acknowledgement that this 2-week email practice rocks.)

From EO:

“After purchasing an optical component, exercising proper care can maintain its quality and extend its usable lifetime. Choosing the proper cleaning products and using the proper methods are as important as cleaning the component itself. Improper cleaning practices can damage polished surfaces or specialized coatings that have been used on optics such as lenses, mirrors, filters, or gratings, degrading the performance in almost any application. Also, be aware of your clothing and your environment while cleaning optics; shirts with zippers and buttons can scratch your optics, likewise dirty or dusty environments are not well suited for optical applications.”

Enjoy!

:DW

Spectroscopy

PChem at SHSU, What to Expect

Posted on August 25, 2014August 25, 2014 by D. L. Williams

Most of our frustration in life stems from incorrect expectations. So let me line out the year of PChem at SHSU so you will not be frustrated by the unknown.

Starting at 30,000 ft elevation, we have the two semesters:
Fall is Quantum Mechanics and Spectroscopy
Spring is Thermodynamics

Zooming in on the Fall semester, we have the following structure.
Quantum Mechanics, Spectroscopy, and Group Theory fully developed on one-dimensional systems.
QM applied to vibrational spectra
QM applied to rovibrational spectra
QM applied to atomic spectra
QM applied to electronic molecular spectra
Spectral simulation with Gaussian

This is a significant departure from the structure of my undergraduate pchem course at UT in the late 80’s. And in my opinion, it is a great improvement!

My goal for the class is for the students to be able to apply a quantum view of light interacting with matter whenever necessary.

I know this approach has been successful because alumni have written me saying that they were able to understand spectroscopic applications not covered in my course. This course gave them the skills to apply the theory in new situations, which is the greatest goal of higher education.

Drilling down into Thermodynamics, I break the course into five sections.
Statistical Thermo taking quantum theory to bulk properties.
Thermochemistry the theory of bulk properties and engines.
Phase diagrams, pure substances, mixtures, and equilibrium.
Non-equilibrium systems and transport phenomena.
Energy sources, sinks, conversion, and efficiency.

This is also a departure from the traditional pchem Thermo treatment, which in my experience was a class in partial differential equations taught under the guise of a chemistry class.

Is this treatment effective? Once again, I rely on alumni to support my claim that it is. They are well employed and advancing in GE, Baker Hughes, Nalco, Agilent, and other competitive companies.

D L Williams, Education, Physical Chemistry

Brainstorm Session on 3D Printer Waste

Posted on August 21, 2014August 21, 2014 by D. L. Williams

Friends, Romans, Countrymen, lend me your ideas. Look at the picture of the dual extruder tip cleaning fences and give me your thoughts on what they could be used for.

Background: I have recently added a 3D printer to my lab to prototype chemical laboratory accessories.

I purchased a dual extrusion Makerbot and I love it. I will blog a review of its performance sometime soon.

Technical Details: Aside from the waste produced from being a noob at 3D printing, there is also a lot of built in waste from raft and tip cleaning fence material. Turning off rafts and supports does not save filament because these help ensure a successful print. If the print fails without rafts and supports, then you have still wasted a lot of filament.

So get those creative juices flowing, and comment on what you would use these tiny little fences for. Toys? Rear view mirror bling? Let me know.

Spectroscopy

All About Slugs (Not the Slimy Kind)

Posted on August 21, 2014 by D. L. Williams

Excellent advice for searchability.

The Daily Post

When we start writing a new post, WordPress automatically creates a URL for the post using our blog’s address, the date, and post title. Great, now you don’t have to worry about your post’s URL, right? All taken care of.

Not quite. You don’t need to lose sleep over your post URLs, but paying some attention to the post slug — the bit of the URL after the address and date — can have a nice traffic payoff.

“I’m still not sure what a slug is!”

The slug is the bit of your post’s (or page’s) URL that describes what that specific post is about. Here’s the URL of this post, with the slug in bold:

http://dailypost.wordpress.com/2014/08/15/post-slugs/

If I’d used the URL that WordPress auto-generated for me based on the post title, the slug would have been:

http://dailypost.wordpress.com/2014/08/15/all-about-slugs-not-the-slimy-kind/

They both get the job done, but one…

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