I need to come up with a difficult thermodynamics and/or equilibrium problem for my chem 203 class... If the problem is good enough we get do drop one of our three quizzes this year. We have to submit a full solution as well.

Anybody got a problem they had trouble with or that you would think is good enough?

 

he he he....
sorry man, i wish i could help you out...but, it's been a few years (two, actually) since my last chem class and i was sooo glad to be finished it. i forgot everything i learned 5 mins after the final.

now i only concentrate on electrical engg stuff...but don't worry, i'm sure you'll get through it.

 

Calculate the difference in gibbs free energy of ATP between someone who is healthy and someone who is sick with the flu....

Might be OK for colledge.. if this is uni Ill give you something more difficult... [img]tongue.gif[/img]

 

I kinda got one...

A(g) + B(g) <----> C(g) k=130

You have .4061 mol of C in a cylinder, closed with an ideal piston (outside pressure is 1.00 atm).

A) If T is constant at 300.1 K and the initial volume is 10.0 L (before C begins to decompose), find the volume when equilibrium is reached.

That was kinda easy (as long as the answer is 11.28L), so i decided to add in:

B) Calculate delta H, delta S, Delta E, delta G q, and w per mole of C decomposed.

But I'm not really sure how i would do this, or even if you can. Could you treat it as a simple isothermal ideal gas expansion, or what? If not is there something i can ask that is thermodynamics-related?

[ March 22, 2005, 09:12 PM: Message edited by: deyton ]

 

Maybe Iam a little out of it at the moment but your question isnt adding up for me...

Assuming you have an ideal gas you either have less then 10L to start, more then .4061 moles of gas, or the internal pressure of the piston is less then 1atm.

Assuming the latter you will end up with 4.33L at eqm before the temperature goes up (you can find expansion work if you want)... and at 300K with the gas decomposed you are looking at 20L


[img]graemlins/dunno.gif[/img]

 

Well here's how i did it, maybe i didn't explain it very well (mine on paper has a picture [img]smile.gif[/img] )

Initially the pressure of the gas is 1 atm (has to be otherwise the piston would be moving).
V = (nRT)/P = (.4061*.082057*300.1)/1 = 10.00 L.
C(g) <----> A(g) + B(g)
is what's happening, with a K of 1/130. To reach equilibrium you lose a 'x' moles of C, which creates x mol of A and x mol of B, with a net gain of x mol of gas.

1/130 = x^2 / (.4061 - x)
x = .052177
Now,
V = ((.4061 + .052177)(.082057)(300.1))/1 = 11.28L

I can't seem to find anything about gibbs free energy for expansions, so i'll probably just do delta H, delta E, q, and w.

[ March 22, 2005, 09:27 PM: Message edited by: deyton ]

 

ahhaha.. it helps when you have that paper
(I though 130K was the inital temp and not Keq [img]smile.gif[/img] )


everything looks good.. gibbs energy at constant temp = enthalpy - entropy if you want to figure that out..

If you wanted to add another level of complexity you could try and find a real gas to use... like N2O decomposing at 1200K... so long as you can find vanderwal consants for the gas you are using you can do it...

 

Well it was due today, i'm pretty sure it worked out well. It didn't have to be great, i was just looking for ideas. Thanks a lot.