The Chemportal

I've picked this problem from some general chemistry files that were retrieved from some tutoring sessions during my undergraduate years in chemistry (where I was the tutor).  Let me know if there's anything erroneous in the content.

When a mixture of xenon and flourine is sealed in a glass bulb and placed in the sunlight, beautiful crystals of XeF2 are slowly formed and deposited on the walls of the container. (XeF2 is a volatile solid with a vapor pressure of 4.5 torr at 25 degrees C).

In one such experiment, a 10.0 L glass bulb is filled with 1.00 atm Xe and 0.100 atm F2 at 25 degrees C. After sitting in the sunlight for a period of time, 4.60 g of SOLID XeF2 is formed. The bulb is then removed from the light and the reaction stops. Determine the partial pressure of each gas in the bulb at this point in the reaction.

Since XeF2 solid was formed, the container is saturated with XeF2 gas.  The quantity of Xe and F2 which together formed XeF2 (g) can be ascertained by considering how much of XeF2 (g) as well as XeF2 (s) was produced.

Due to saturation, the vapor pressure of XeF2 is 4.5 torr, to find the number of moles of XeF2 gas that exists, the vapor pressure value is incorporated into the ideal gas equation.

4.5 torr XeF2(1 atm/760 torr)=0.0059211 atm XeF2

n=PV/(RT)=0.0059211 atm XeF2(10.0 L)/(0.08206 Latm/molK(298 K))= 0.0024213 moles XeF2

The problem states the amount of XeF2 that was formed as a solid, this amount is converted to the mole unit. 

4.60 g XeF2(1 mole XeF2/(131 g + 2(19 g))=0.027219 moles XeF2 solid

The total number of moles of XeF2 that was formed as a gas and solid is thus,

.0024213 + 0.027219 = 0.029640 moles XeF2 has formed

This means that we need to subtract this amount from the initial mole values for Xe and F2.  The stoichiometric equation, Xe (g) + F2 (g) ----> XeF2 (g), indicates that the ratio between the reagents and products are unity; the number of Xe (g) and F2 (g) are equivalent with the number quantity of XeF2 (g) that is subsequently produced.

Moles of Xe (g) consumed = Moles of F2 (g) consumed = Moles of XeF2 (g) and XeF2 (s) 

PV=nRT, n=PV/(RT)=0.100 atm F2 (10.0 L)/(.08206 Latm/molK(298 K))=0.040893 moles of F2

The amount is 10 times greater for Xe since its initial vapor pressure is 10 times higher

1.00 atm/0.100 atm = 10, 0.40893 moles Xe

0.40893 initial moles Xe - 0.029640 Xe reacted = 0.37929 moles Xe remain
0.040893 initial moles F2 - 0.029640 F2 reacted = 0.011253 moles F2 remain

Incorporate these values into the ideal gas equation to calculate the pressure value.

P=nRT/V=0.37929 moles Xe(0.08206 Latm/molK)298 K/10.0 L=0.92751 atm Xe

P=nRT/V=0.011253 moles F2(0.08206 Latm/molK)298 K/10.0 L=0.027518 atm F2

0.0059211 atm is the vapor pressure for XeF2 as was stated already at the introduction.

Edited 02/27/2007 for simplification.

My professor from the last BS Chemistry major (ACS certified) course has yet to grade my last report that was turned in for an independent research course DURING THE SUMMER OF 2006.  It was noted, in one of the past post here that I was grateful that he would edit the paper in the first place, however, I haven't heard from him in a while and had called the chair of the Chemistry department out of curiosity.  It seems that this isn't the only time this particular professor of mine deliberately cased this type of trouble in the past with students.  In fact, it was revealed during a phone call with 'chairman' that he is scheduled to retire by Christmas this year, due to this "quirk" of his....the event was "arranged".  The "quirk" in his personality is small, however, it has been deemed unacceptable in consideration of the quality of education that the students in the Chemistry department receive.

It turns out that he hasn't gotten along with the chairman very well in the past.  He (the chairman) had stated that this professor does these type of things due to an ego, a very eccentric one indeed, and one that is annoying to the staff as well as the students.   He volunteered to meet with the professor right away.  However, I had asked he not be reprimanded until early March, should the situation be present then.

Albeit, I'm not so concerned about getting this report graded, which is going to officially end my undergraduate academic session.  From the information that was presented to me from the chairman, however, this case seems a bit freaky and disconcerting.

He has a nice personality overall; college has taught me to be open minded, so instead of just concluding that he was "weird", I had dealt with him through a professional manner until now.    Maybe he's planning something in his desparate state.  He's not senile, I've talked with him a few times about this, and all of it seems deliberate.  Perhaps, the reality is that (the non-dramatic one) is that he doesn't want to grade paper.....and that he is just aging, all in all folks, the lesson here is to always pick the right professor for whatever course you take, especially those that involve research.

I had to report at work today by 5:00 A.M. due to a validation protocol that is being implemented over two weeks (including the one we're on currently).  First I didn't recharge my phone, then I didn't bring my electronic key, and I was low on gas........the third factor would have been problematic since no gas stations are open at 4:00 A.M. in the morning.  HOWEVER, a Quick Trip gas station was open ("QT"), in fact, it was basically the only place that was in business at such a time. 

I saw seven other cars on my way to work, one of them was a police car which was right in the middle of the road, apparently the cop was taking care of business with two other cars; perhaps they got caught "under the influence."  He eventually noticed that the traffic was building (the four other cars I witnessed during the whole trip to work) and made way to direct it around the two cars to which he was attending to.

I arrived at the work site to find that I had not brought my electronic key to access the building, the battery was quite low on my phone,  I was hoping that an anvil would drop from the sky, knock me unconscious, put me out of my misery.  I was able to make a single phone call to have one of my co-workers open the door from the inside.

I may apply to graduate school within the year, it's not too advantageous from a salary and general job availability consideration, however, it would definitely aid in becoming an expert in a variety of fields as opposed to being confined to becoming well versed in one special area.  As far as administrative positions go, a B.S. degree seems to be equivalent to an M.S.; the prospect of getting into industrial research seems to favor the M.S. candidate a bit more.  Yes, until now, I've been referring to the industry, one definitely needs to progress up the ladder from B.S. to M.S. and even towards a PhD to flourish in academia, even perhaps, to survive in it; you're not going to be a graduate student forever.

Chemistry is just more fun with a M.S. degree, one can be more versatile with it that's for sure, even in industry.  I can hope to become a research scale industrial Chemist, however, I would be competing with all of the other candidates out there on the level of intelligence, and it won't be so easy getting into an R&D department of a reputable company which is doing research that is of interest to me.  One would have to be pretty creative with a B.S. Chemistry degree to sustain oneself as an R&D Chemist with the authority to conduct research and provide advice on an independent, non-supervised, level of work.

Since I'm not too talented in research, the main incentive for attending graduate school is soley to learn more Chemistry.  If it was strictly a pay basis, graduate school shouldn't be substituted for experience in the industry; some people get paid a meager $18,000 a year during their session in graduate school, then don't really find a job with an M.S. degree since they are expected to know a lot more.  I know of a girl who came out of University of California with an undergrad, and went to the University of Iowa for her masters, she got paid the ~$18,000 a year and has graduated recently with a not too happy kind of look on her face.  It seems that she didn't really develop much as a Chemist and now her sole option seems to be to become a community school professor.

Blog.com is currently having some bug problems with their blog layout feature, it's been a couple of weeks now and thus it seems that they have other priorities.  'Chemportal.blog.com' may become 'Chemportal.wordpress.com' or 'Chemportal.blogspot.com' pretty soon.

"Hey Caroline! It's Kat, and I am freaking out right now. I opened up my lab manual
earlier today to do my pre-lab for tomorrow and my manual is completely missing
Lab 3!?!?! I tried to send you a message on facebook, but thought maybe if I e-
mailed you also it might help! I also tried contacting my lab partner but with no
response. I even e-mailed Shim and am still waiting for a response from her also.  I
was wondering if you could help me out with my wonderful :) problem. Give me a
call at ***-***-****! (the number is not shown) thanks so much girl!
--kat "

Yeah, she gave me her phone number....he, he, he

P.S.  My name isn't Caroline.

Most of you are probably familiar by now regarding the bizarre story of the NASA astronaut Mrs. Novak and her attempted murder charge initiated by Colleen Shipman.  She's obviously intelligent or perhaps more of an overachiever, but on Tuesday she took the plunge into "wonderland" from the platform of reality.......yep, she drove herself completely out of this world.  She is a rocket scientist who turned into a imbecile-moron, pleading with the victim, Mrs. Shipman, to open the door so that she could kidnap her. 

This case is SO WEIRD, and it's one of the few cases where analysis reveals several aspects which are WEIRDER STILL. 

She was obviously in some type of total despair and seems to have an indulgent disposition.  I would say that it is the latter characteristic which separates her from 'normal'.

She may have confirmed her worst fear when her marriage ended, this shattered a fragile image of herself, which was employed previously to suffice in satisfying an indulgent personality.......the next best incentive was her desire for a certain man.  I could somewhat identify with this situation, and I'm sure that many others can also.  If you're someone who strives for a perfect grade point average, and you obtain a C+ on a biology test as an undergraduate at a certain university, the consequential tendency is to become delusionally impulsive.  Part of this is because the individual has basically set himself/herself up for a state of shock.  It really depends on how much of a habitual perfectionist the individual is.  Apparently, her "image" was on a relatively grandeur scale then most people, and she had a bad personality to go with it.  She's truly unique and what she did is truly sad.  I'm pretty sure that she wouldn't have actually killed Mrs. Shipman and hopefully the court is going to recognize that she had some type of an amnesically insane episode.

The public view of chemists is of at least two views.  One belongs to the middle aged generation where the Chemistry courses which they took were relatively simple to the "quantum mechanical chemistry" it is today.  A chemist is merely a scientific cook, and his job consists of measuring quantities out carefully, being aware of certain sets of reactions, is knowledgeable about chemicals,  knows how to assess the subtleties of what's going with respect to the physical aspects of experiments, but is otherwise ignorant and answers to a higher authority.......that is the mathematicians and physicists in maintream science.  By ignorant, I'm referring to the public notion that chemists are ridiculously untrained in such dizzying equations and math that the physicists wield. 

Chemists are laughable, for the 49 year old Engineer, he remembers his prerequisite Chemistry courses as inferior to the standards that were set by his higher level math and physics courses.  Yes, chemists are better off in the lab hoping to come across something that's vaguely useful.  Chemists obsess over the quality and cleanliness of their flasks and beakers and a degree in Chemistry is easily attained.

However, those individuals who took introductory Chemistry recently, either for their pre-med major or for some other prerequisite that was specified in their degree program guidelines,  know that the content of modern introductory Chemistry courses has complex mathematical formulas to utilize that stem from higher level mathematical proofs derived by such scientists as Josiah Gibbs ("father of thermodynamics") and Schrodinger (one of the foremost contributors to the development of quantum mechanics).  This is because the field that is considered to be 'Chemistry' is increasingly becoming 'quantum mechanics', everything is explained in a "quantum" perspective.  Acids and bases are explained with relevance to frontier orbitals by Pearson's HSAB theory by maximizing highest occupied molecular and lowest unoccupied molecular orbital interactions.  A lot of this type of in depth quantum explanations of general chemistry concepts are detailed in standard inorganic chemistry texts.

Dr. Thomas Albright, The University of Houston, Chem6311

A chemist this day and age must also attain working knowledge of fundamental high tech analytical instrumentation such as the FT-IR, UV-VIS, MS, GC, HPLC, Potentiometer, NMR as well as even more "higher order instrumentations" and be able to analyze the resulting forms of data (e.g. spectral) that are prepared by the devices. 

I, for one, took all three calculus courses as well as differential equations.  An ACS certified chemist is highly trained in the maths, although he or she may not have been greatly successful in those courses, the opportunity to excel in hard core fields is all there in the undergraduate chemistry program.  One can become incredibly versatile in scientific research prowess with an ACS certified Chemistry degree from a good college.  It is the quantum side of Chemistry that makes it an irrefutable quantitative science.......and this fact relates to the second prevalent view of what it is to be a chemist.

Revised as whole for clarity 02/02/2007