Ch6 lec 1
(4/6/2020, bes)
Greetings!
Great job getting through the WA exam. I know that this experience was not perfect for everyone...one of you could not even see the "buttons" to select an answer (weird, but it is a computer)...but overall, i feel that it was acceptable/successful. I made a small mistake in the coding...when i added the last "essay" questions to the exam...the WA system by default assigned 1 pt to each response...so...you had the option to get 3 bonus points by responding! Yes, it was listed as optional, but i guess that is another name for extra-credit? So, the exam was out of 100 pts, you had an opportunity to earn 103 pts...you can see your score, which is equal to the %; one of you got a 103%.
About those 3 additional questions:
So when asked "How is online Gen Chem going?" you responded:
Response 1
going really well, it is awesome...to difficult, stressful, harder to learn on my own...to terrible, awful.
- My reply: Taking an online course is not for everyone. After 20 years of teaching, i hope that what we do in the classroom/in-person, supplemental instruction/tutoring, and the facilities we can provide for labs is better than what we are currently doing...otherwise we need to rethink all of education! Again, online courses are not for everyone and hence the people who replied positively to the question (going really well, it is awesome) would be the folks who would sign up for an online course, BUT NOT ALL OF YOU WERE GIVEN THIS OPTION...it was just dropped in your lap.
- Additionally, if you were going to sign up for an online course, you would probably already know that you have quality internet and a relatively new computer/laptop. Having this dropped on you as a non-elective mode of learning, you were not given the opportunity to acquire all of the tools needed to fully utilize an online course experience. Take home: don't be too hard on yourself, these are truly unique times (i never expected this would happen).
Response 2
"it would be nice to have some video/Zoom sessions
- My reply: As noted above, since this online mode of delivery was not your choice, it is most likely the case that not everyone has quality internet /computer needed to stream video...now i could be wrong, but from talking with my colleagues who are using Zoom, there are new and interesting unforeseen "problems" that are not only associated with quality internet, but other issues related to the fact that nearly all elementary, middle, highschool, and college courses are now being taught online, not to mention that many professionals are working from home.
- Some of my colleagues are teaching class in the same way they did prior to spring break...a the normal 8 am lecture meets at 8 am...but nothing is NORMAL now...hence, they are having to record and upload videos to accommodate future viewing. This results in an additional resource/location of content to keep organized. I personally think that i could do a good job putting together a collection of videos to discuss key Gen Chem topics, but not in the time frame that we are on. Take home: after Easter Break, i may setup a Zoom office hours (11 am M-Th)...stay tuned. by the way, MC did get a license for all of us to use Zoom, but we may be shifting over to Microsoft Meetings...???...
Response 3
a lot of work, too many WA, hard to keep track of everything
- My reply: I personally have now learned that i cannot cover the same amount of material in an online delivery mode than i can do in class/lab...but i am now just finding this out. I don't mind making you work hard, but i can write down topics faster than i can teach them and certainly faster than you can learn them. So, i agree with many of you who said that the current Gen Chem is more work now than before and that there are more WA than before.
- Here is my strategy...give a short text-lecture focusing on the sections in the textbook that are the most important, add a few examples in the lecture, then have you work these examples in WA. For this reason, with each lecture there was a corresponding WA that was due 2 days later (or more)...ie 8 am Mon lecture WA was due 8 am Weds. This is a large contrast to what we were doing, ie. one to two WA for each chapter, allowing you more freedom to schedule your "homework" times. My fear of allowing this flexibility at this time is that if you will fall behind and then you will need to ask question about material that is ~ 1-week old. As i have expressed previously, the chemistry you learn today will be used tomorrow and beyond (cumulative). And yes, sometime WA problems ARE more difficult than the basic ones discussed when introducing the content. Take home: i will lighten up on the content/lecture size, but i will continue to assign a WA for each lecture (when appropriate)...PLEASE ask for an time extension if needed.
Response 4
please email use when notes/labs are posted
- My reply: I can certainly do this, but since class meets 3 times per week (MWF) with a lab, you should expect to receive a text-lecture each MWF with a lab activity sometime M or T. I don't want to send too many emails and possibly make this more complicated. Take home: expect a lecture MWF usually with a WA to follow due before the next lecture.
Okay...I am happy to chat more individually, but it is time to move on!
Chapter 6: Thermochemistry
The chapter is rather short. Content can be divided into two sections: theoretical and experimental. There is some math involved, but the take home message is fairly concise...in chemical reactions heat is often a product. This chapter describes for us how we treat heat as a product (or reactant).
Sec 6.1 The Nature of Energy and Types of Energy
READ
Main concepts:
- - Chemical energy is stored within the structural units of a bond. When reactants participate in a chemical reaction, products are produced, but ALSO...energy, usually in the form of heat is release, stored, or converted to another form of energy (motion or light).
Sec 6.2 Energy Changes in Chemical Reactions
READ
I often start this chapter by doing a demonstration similar to this --> see Hydrogen-Oxygen Reaction.
- (Luckily, this is not a reaction that you can do at home since hydrogen and oxygen gas are not readily available - as a chemist, i know how to make these...)
This is a fairly simple reaction that produces a lot of heat!
H2 (g) + O2 (g) --> H2O (is this balanced? pls balance this reaction in your notes.)
What was not mentioned in this short video was the ratio/amount of gases added to the 2L bottle. From the balanced chemical reaction, you can see that the reaction requires twice as much hydrogen gas (2 moles) as oxygen gas (1 mole). When doing this demonstration, i make a point to show you this as i prepare the bottles of H2/O2 in the classroom. By the way, i use a 250 mL bottle that does not rupture!!! If you recall, there is a picture hanging in the hallway on the 3rd floor of CSB that is my hand holding a bottle of H2/O2 that had just been ignited...picture was taken with the high-speed camera owned by the Math Dept (Mike Sostarecz).
One of the points noted in the text is that depending on whether the "system" is opened or closed, one would expect very different "chemistry." The 2L pop bottle video above is a closed system, that ruptured violently when the reaction was initiated. Being a closed system, the hot gaseous products created a pressure greater than 200 psi which ruptured the bottle. If only hydrogen gas is put inside of a container (like a balloon), then the result is a "fireball" not an rupture/explosion. An example of a hydrogen gas "fireball" was the Hindenburg:
The above reactions are "exothermic" meaning that they give off heat...as you can see in the flames. Other reactions are endothermic, in which heat is consumed...these are less exciting, but they do happen.
END of Lecture...NO WA today!
Sec 6.3 Introduction to Thermodynamics
Weds, April 8th
- Easter Break: No class on Friday, April 10 or Monday April 13th.
Sec 6.4 Enthalpy of Chemical Reactions
Weds, April 15th
Sec 6.5 Calorimetry
lab - April 6th (see other link)
Sec 6.6 Standard Heats of Formation
Friday, April 17