PChem322 s22 w1

...return to Chem 322 - home

Weds, Jan 12, 2022

Announcements

0) Nearly all of you in PChem II are also in PChem I. There are some introductory topics that I want to share with all PChem students, so there is some duplication of assignments at the beginning of Chem 312 and 322. Only complete items below that are new to you.

1) If you have not done so, please review the syllabus linked here.

2) Question: Is your computer up to speed? During this course, we will be using software such as Excel, WORD, Igor, Mathematica etc. Although there are computers available on campus (specifically in CSB 373), it is most convenient for you to install this software on your computer (laptop preferred). It may be the case that a "ChromeBook" or other cloud-based OS device may have sufficed in the past, it will not work in PChem...but computers will be available in CSB 373. Please see/email me with any questions.

Class Assignments

1) I would like for you to watch the following video that discusses being proactive vs. reactive. I have found that PChem students who are most successful would describe themselves as being proactive. I think you will agree that we should all shoot for being proactive in our lives, but this is a clear skill that even I am working on improving. The video moves quickly, so I suggest you just listen the first time, then consider coming back to this view it again at another time. We will discuss this more in class when we meet in person.

Proactive vs. Reactive

2) If the above material is interesting, consider learning more about Stephen Covey or how to use the Franklin Planner.

Steven Covey - Wikipedia (optional)

Franklin Covey - Wikipedia (optional)

Franklin Planner - Wikipedia (optional)

Weekly Planner example page (optional)

...now on to PChem...

3) It is time to start reading the text. Please note, that reading any science textbook is NOT like reading other documents. The information is presented in a very dense way...this means that there is a lot of scientific language that needs to be read multiple times in order to make sense. The Quantum textbook (Chem 322) is more clearly written than the Thermodynamic textbook (Chem 312). The authors, Engel and Reid initially published a single textbook containing both sections called "Physical Chemistry" (literally the two books bound into one). In addition to the single textbook, the publisher always printed the two sections separately; the 4th edition of this textbook is only printed as separate sections...no more single textbook containing both. As you will note, the Quantum textbook is written by Engel alone. I meet this author and had lunch with him at the 2017 Denver ACS meeting: great guy, has essentially retired and works mainly on gardening and editing his textbooks.

- Let's start by reviewing the MATH ESSENTIALS 1 section (Page 1-3). As you might already know, PChem uses the language of mathematics to organize its contents. Calc 1 and Calc 2 are prerequisites for this course (although they are sometimes waived). Yes we will be taking derivatives and integrals, but more importantly, you need to be comfortable with math in general. Math is a tool and by the way, you cannot hate a tool, as in..."i just don't like hammers." Although you may have had a bad experience with math in the past, i will present math in a way that you will find it helpful...like how a hammer is really good at driving nails!

• Please review this section (pages 1-3) now. In your notes, please write down all of the units listed in Table ME1.2 and indicate whether you are comfortable with these units (check) or not (???).
• In Section ME1.2...sig figs...this is something you should know well!
• In section ME1.3...they suggest that writing out all of your work is strongly suggested since it allows you to go back and correct any errors. Please work this problem in your notes as if you were going to answer this question on an exam (ie. Show your work). Now use Excel to reproduce the spreadsheet shown at the bottom of page 3. You do not need to turn this in right now, but i will ask to see it later. At a later time we will use Mathematica to solve such problems.

- The next pages in the textbook are an additional 3 MATH ESSENTIALS sections (2-4). These will be VERY handy in the future as a place to look up derivatives and integrals, but for now let's skip these sections.

- The first Chapter of the textbook makes a strong case related to why we need quantum mechanics and not just classical mechanics. There are 4 experiments done in modern times (last 100 years) that have shown that classical mechanics cannot explain the experimental outcomes, the experiments are named:

1) Blackbody Radiation (Sec 1.3)

2) The Photoelectric Effect (Sec 1.4)

3) Particle-Wave Duality

- Particles acting as waves (Sec 1.5)

- Waves acting at particles (Sec 1.6)

4) Emission Spectra (Sec 1.7)

For now, i would like for you to read Sec 1.1 and 1.2, but get ready to do some math shortly.

END

Thurs, Jan 13, 2022

Announcements

1) I sent you an email regarding Mathematica. If you have not already done so, please send an email to Mike asking for a student copy of this software. We will be using this frequently.

2) With the smaller class size i see no reason that we should not meet for lab next week (Thurs, Jan 20 at 2 pm). Make sure you wear your N_95 mask. This may have to change depending on the campus COVID status.

Lab Activity/Assignment

1) Install Igor software on your computer...go to here and download version 8.0. Although you can use the software for a 30 day trial, I ask you to register/activate your copy using the info in this image/below (click on it to expand) ->

VAPG-PDSX-GZLA-XPKY-MJYU-YLUX-KNS <- cut and paste:

2) In PChem I (312) you were asked to watch the NOVA: Absolute Zero, The Conquest of Cold (first 52 mins). There is a second part of this NOVA program, NOVA: Absolute Zero, "The Race for Absolute Zero" that carries on the history of thermodynamics and leads to the development of experiment that require some other form of explanation, ie. quantum mechanics. As we discussed in "lecture" on Weds, there are modern experiments that were not explained by classical mechanics. As you watch this video, keep this in mind; as experiments get more and more complex/involve we learn more about the details of the physical/chemical world...requiring more and more complex explanations. This video is ~60 mins, but i suggest that you take a 5-10 min break after the first part (a):

a) 0 - 48:46 mins (main program including Bose-Einstein condensate)

...then finish up the last ~10 mins...it is up to you.

b) 48:46 -> 55.46 min (interaction of Bose-Einstein condensate with light, superconductivity, medical - MRI, quantum computers)

c) 55.46 -> 58.38 min (concluding remarks/summary)

Program Expectations...recorded in your lab notebook; carbon copies will be collected for evaluation:

1) Document all historical people and topics mentioned throughout the program,

2) Use the summary at the end of the program to draw out a temperature timeline...and add the points where O₂(g), N₂(g), H₂(g), and He(g) liquify.

3) Challenge: Attached here is an Excel file that reproduces part of figure 1.2 (Blackbody Radiation).

We will discuss more about blackbody radiation in lecture tomorrow. For now, please download the Excel file and add the other data to the Excel graph. I am in my office until ~5pm, if you need any help.

Friday, Jan 14, 2022

Announcements

1) Well it was not a full first week, but we have made it! Congrats.

2) As a reminder, we will meet next week in-person for lab on Thurs. There are only 6 of us in the class so we can distance easily in CSB 373. Bring your laptop or you can use one of the desktop computers in this space.

3) At this point, you should have Igor and Mathematica loaded onto your laptop. If this is not the case, you have more homework than i assigned. If you are having any issues please let me know and we can either get together and work this out or do it via email/phone. We will use both software packages in lab next week.

4) The NOVA program never gets old. There was a statement made in the program stating..."I am foot soldier of science." As you think about the early days of the development of scientific principles there are certainly key historical players (now written down in your lab notebooks), but let's not forget all the others who work behind the scenes (the foot soldiers) making thermometers, preparing samples, etc, without them science would progress at a snails pace. Although it may be a bit too earlier for you to contemplate your role in science, but you too are a foot soldier. You represent a critical part of the scientific ecosystem. Some of you will go on to be the Antoine Lavoisier of your time, but most of us will continue to be foot soldiers for science and as you might expect, the scientific ecosystem needs lot os foot soldiers! Keep up the good work. If this topic resonates with you, consider having a look at this paper titled, The foot soldiers of science.

Class Assignment

1) I am excited to hear that all of you were successful in completing the Excel Challenge i gave you in lab yesterday dealing with reproducing Figure 1.2, the Blackbody Radiation problem (Sec 1.3)...otherwise i would have heard from you. Although it is not necessary to fully understand the concepts of blackbody radiation (BBR) in order to complete the Excel graphing, you may have looked over section 1.3...or not. Let's do this now...

BBR is fairly simple, hot (any temp over absolute 0) objects emits (or radiates) electromagnetic radiation (light). How do we know this? We built sophisticated scientific equipment in order to measure the properties of the emitted light...frequency (ν) and intensity. Figure 1.2 (page 21 and above) shows that an object at 6000 K has a ν_max of ~3.5e14 Hz...meaning the frequency of the maximum intensity of light emitted (ν_max) is 3.5e14 Hz. If the temperature of the object is lowered to 5000 K, then the ν_max = 2.8e14 Hz...and so on. The ν_max is dependent on the temperature.

The equation i used to reproduce this figure in Excel is eq. 1.7. Eq 1.7 is presented as a differential equation, ie contains a variable of differentiation, dν...i simply removed the dν and treated the ν as the x-value and the spectral density (ρ) as the y-value. As you will read, when classical mechanics was applied to the problem of BBR this "math" predicted that all objects would radiate light in the ultraviolet and above regions, which would be catastrophic...we would all be dead...hence the ultraviolet catastrophe. As stated in the reading, it was Max Plank who figured out the math...which required him to treat the energy of the "oscillators" as if they had only discrete energies and not continuous as classical mechanic predicted. The constant now called, Plank's constant was required in his derivation.

2)Sec 1.4 The Photoelectric Effect

Please read this section. The quick and dirty explanation of the photoelectric effect (PE) is this...when you shine light, with high enough energy, onto a metal surface you knock off electrons (theses are referred to as photoelectrons, although they are no different from any other electron). These electrons leave the surface with a certain velocity. It turns out that the energy of the light (hν)= the energy which holds the electron on the surface (i.e., the work function, φ) + the kinetic energy of moving electron (1/2mv², where v is velocity). This figure 1.4 below shows that as the energy of light (plotted as the frequency on the x-axis) vs the kinetic energy of the photoelectron (y-axis) yields a straight line with a slope equal to Plank's Constant! Here is a totally separate experiment (from BBR) that requires the exactly same constant of 6.626e-34 Js.

Study example problem 1.1 to help you complete the Photoelectric Effect worksheet.

Have a great weekend...be safe...be smart...relax.

END