physics help!!!!!

[lastbastion]

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Okay, I've been doing some study for the MCAT and so I'm doing problems out of my old physics book. However, I have been long removed from physics and can't seem to remember how to do this problem. Please help me out. Here it is:

A 4.65 mol sample of an ideal diatomic gas expands adiabatically from a volume of 0.1210 m^3 to 0.750 m^3. Initially the pressure was 1.00 atm. Determine: a) the initial and final temperatures; b) the change in internal energy.

I calculated the initial temp to 317.014 K. However I can't seem to reach the correct final temperature given in the back of the book. Either they made a mistake or I'm just a dope. Please help me feel better by giving me some guidance. Thanks guys, I appreciate it.

peace.

 

[lastbastion]

bump...please?!

 

[YaFwiendToluene]

You are given V(initial) and V(final)

V(i)=0.1210 m^3
V(f) 0.750 m^3

PV=nrt, manipulate algbraically to find the temperature, which should be T-initial.


You used v(i) in the ideal gas equation to find T(initial), you take your v(f) and solve for it in the equation to get your T(final)

T(f)-T(initial)=Change in temp. = T(final)- 317.014 K =delta T

I am assuming that the change in the energies could be found by taking v(f)-V(i)= your change in volume. Plug that into the ideal gas equation and solve for your unknown.

Hope that helps.

 

[lastbastion]

Thanks for giving it a shot. I appreciate it lots.

Yeah, I'm unsure about what I'm supposed to do here. Anyone else have any ideas.

What about PV^gamma?? Of course I don't know how to use this either.

 

[lastbastion]

sorry, PV^gamma=constant

 

[lastbastion]

Never mind, I figured it out. Thanks.

 

[YaFwiendToluene]

What mistake did you make? I am curious to know

 

[lastbastion]

had to use PV^gamma=constant equation, I just had to read the chapter over.