Author Topic: Help Puhhhh-leeease  (Read 1988 times)

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Analy_sis

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Help Puhhhh-leeease
« on: October 27, 2001, 10:29:00 PM »
I need some help with my gas law equation formulas, Well one in specific. It's the week end so I can't bug the shit out of my professor, That man would fall to pieces with out me constantly under his feet and Home made apple pies for tutoring. (I'm So sweet)(took me a week to convince him there was no anthrax in my pies)
Here Goes.....I just cant figure the formula for these 2 equations these questions have been kicking my ass across the room for several days, Chemistry study may have melted my brain, any other formulas pop right into my head.
question #1 A certain quantity of neon gas is under 1.05 atm at 303K in a 10.0L vessel. How many moles of neon are present????
Question #2 A Sample of gas at 77C and 1.33 atm occupies a volume of 50.3L.
a) How many Moles are present?
b) Does your answer depend on knowing what gas it is?
   Puh-Leeease Don't give me the answers to the problems that wont help me, what I need is the Formula for the equations so I can figure the answers my self.
Thanks to every one who answers, Love ya'll
:P

starving 1st yr chem student, Crazy But not dangerous.

hest

  • Guest
Re: Help Puhhhh-leeease
« Reply #1 on: October 27, 2001, 10:33:00 PM »
P*v=nRT
P=presure
v=vol
n=moles gas
R=Gass konst. (8,31451 j/mol*k)
T=temp.

foxy2

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Re: Help Puhhhh-leeease
« Reply #2 on: October 27, 2001, 10:36:00 PM »
And what was your major?
Lets hope its not engineering!!
:-[


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Analy_sis

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Re: Help Puhhhh-leeease
« Reply #3 on: October 27, 2001, 10:48:00 PM »
thanx hest, I took your formula and did P*V/RT
R= 0.0821 L*atm/mole*K
I Got 0.404 mole question #1 book says 0.422 I figure close enough
Question #2 I got 2.33n But the answer to that question was not in the book am I getting warmer ?????
Thanx Analy_sis ::)

starving 1st yr chem student, Crazy But not dangerous.

hest

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Re: Help Puhhhh-leeease
« Reply #4 on: October 27, 2001, 11:04:00 PM »
Thats right.
This was an ex. on using the ideal gass law, there is also an real gass law (pv=nrzt) but z is usual very close to one.

foxy2

  • Guest
Re: Help Puhhhh-leeease
« Reply #5 on: October 28, 2001, 04:05:00 AM »
LOL
That name makes me laugh, the "REAL GAS LAW"
As if there was such a thing  ;D
Not saying thats not the name of that equation, its just after learning a little advanced thermo it makes such a concept funny.

So Hest when I am compressing my ANNY can I just assume an asymetric factor of 1?  :P

;D

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terbium

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Re: Help Puhhhh-leeease
« Reply #6 on: October 28, 2001, 06:11:00 AM »
I wasn't going to say anything but shouldn't this thread be in the Newbee Forum?

Talking about gas laws, I want to know why most gases cool when they expand but hydrogen increases in temperature? I once asked a fellow with a PhD in Thermodynamics about this and he said that it was just the way things are.

foxy2

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Re: Help Puhhhh-leeease
« Reply #7 on: October 28, 2001, 07:05:00 AM »
Here is what I think.

The expansion cooling of most gasses is caused by the gas performing work to push away other gas(expanding).  Since the gas is performing work it is releaseing energy to the environment(just like rubbing your hands together generates heat), this energy must come from somewhere, that somewhere is heat and loseing heat means cooling.  There is also a small component of heating due to entropy, meaning that as the gas expands entropy increases.  Increaseing entropy at constant temperature, pressure and volume means the system has less energy.  If a system loses energy(at constant temp, pressure and volume) it means heat has been given off.   However in real life this released energy must go somewhere and the place it goes is heating up the hydrogen and surroundings.

It appears that for all gasses except Hydrogen the work term dominates.  Maybe the Hydrogen molecule is so small that it can expand without hiting very many other gas molecules and therefore the work required to expand is very small.  This would allow the entropy effect to dominate thereby causeing a net rise in temperature.

Here is the applicable thermodynamic equation

dU = TdS - PdV
change in heat = temperature*change in entropy - physical work



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Analy_sis

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Re: Help Puhhhh-leeease
« Reply #8 on: October 28, 2001, 06:09:00 PM »
The reason I don't post my acedemic questions in newbee is because I figured the more exsperiants chemist would be in anouther forum and I want to ask my questions to the best people I can find. I know this stuff is baby stuff to you but it's brand new to me, and I want to learn from the best there is. Am I still in the wrong forum???? But your question did bring to thought a good idea that I will e-mail rhodium about after I finish studing (4-5 hrs) I will ask him if he would please think of making a forum just for academic help, where collage students can request help with a problem and get a posative encouraging response from willing chemist to aid in our or "My" education. I don't post very often but when I need help I need it right then and this is the best of the best I have found why settle for any thing less? I can't imagine this place not being here for me. For me it is the Golden Grail of chemistry. Love Ya'll Analy_sis

starving 1st yr chem student, Crazy But not dangerous.

foxy2

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Re: Help Puhhhh-leeease
« Reply #9 on: October 29, 2001, 04:50:00 AM »
Hey analysis there already are several forums around the web just like that.

You can get to some of them thru the sticky "LINKS" thread at the top of the methods forum.
Foxy

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Chromic

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Re: Help Puhhhh-leeease
« Reply #10 on: October 29, 2001, 05:43:00 AM »
Why can't all vapours be ideal gases and a perfect gas mixtures? I hate applied chemistry/thermodynamics.

Phosphole

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Re: Help Puhhhh-leeease
« Reply #11 on: October 29, 2001, 08:18:00 AM »
Because the big atoms like to pick on the little ones so they have to get around really fast. Just look what happens when the hydrogen siamese twins hit the palladium atoms - the get ripped apart. Chemistry is such a violent topic.   8)

megamole

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Re: Help Puhhhh-leeease
« Reply #12 on: October 29, 2001, 05:17:00 PM »
Just a suggestion, but in the future, it would help if your typed in how you came to those numbers. When you're first learning, what's most important is that you demonstrate you know how to go about solving the problem, rather than necessarily the right answer. This would help explaining things a lot.

Good luck, keep up the good work.

-megamole

Analy_sis

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Re: Help Puhhhh-leeease
« Reply #13 on: October 29, 2001, 05:35:00 PM »
Thank You Foxy2, I don't post questions like that very often it's usually only on the weekend when I can't harras
my chem prof. (i'm working on that though) He's a damn good teacher. He's in to pyro techs and im trying to use that to get him to help me play with my new organic kit (Nothing illeagl). I allmost got him talked into blowing some stumps out of the ground in the back pasture.(draws to much attention) You ought to see the love in his eyes when i start talking fire. I'd swear the man was getting a woody.I will think of something for him to help me do legally so not to arrouse suspicion or draw attention. We all I guess get into chem. for something, I left truck driving cus of my kids and started going to school because of the love of a good high. It keeps me thin and active helps me escape the hell of reality every now and then. And this place this Holy Grail of forums is the iceing of my acedmic labors, I don't post very often because i keep my mouth shut and listen. I am allways scanning through the Fucking search engine or Rhodiums archives. Believe this or not ya'll have been teaching me to talk like a chemist, now if I can get ya'll to teach me how to spell. No I like it best with birds of my own feather, I don't have to watch my language here or try to hide the fact with cloths or ethics that i,m really just a poor white trailer trash junkie. I look up to ya'll, I want to be just like you, Is that so bad?

starving 1st yr chem student, Crazy But not dangerous.

Osmium

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Re: Help Puhhhh-leeease
« Reply #14 on: October 29, 2001, 05:40:00 PM »
Tell your chem teacher you think smoke bombs are cool, you want to try out a formula you saw on the internet with him, and tell him to order a pound of rP  ;)

Analy_sis

  • Guest
Re: Help Puhhhh-leeease
« Reply #15 on: October 29, 2001, 08:37:00 PM »
ooooooOOO! I have been woundering how I was going to get him to help me clean some old road flares (truck driver can get them by the dozen) If I tell him I want to make some red white and blue smoke bombs in honor of this great nation "of course" and to make my kids go nuts with this all powerful demonstration I bet he'd do it.
Thanks Osmium, Your a genius
    Analy_sis   P.S. You ought to be ashamed of yourself aiding in the corruption of a fine pillar in this small comunity of apple pie USA.
;)

starving 1st yr chem student, Crazy But not dangerous.