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Adiabatic/Isothermal process

  • Thread starter bio87
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Hi people!
So i have a homework question that i am stuck on!!

Four moles of an ideal monatomic gas undergoes an adiabatic expansion from intial volume of 1m cubed and a temperature of 300k to a final volume of 10m cubed. a) How much wrk is done by the gas ? b) what is the final temperature? c) If instead the gas expands isothermally to 10m cubed, how much work is done? d) In part C where does the energy come from to perform the work? ...thats a lot!

I thought of using the equation of work W(by)= 1/(1-gamma) x (PfVf-PiVi) to fnd the answer for a...but I don't have the pressure..:rolleyes: then i thought that maybe I could use deltaE= Q(in) - W (by)...but I don't know the change in temperature, therefore; im all over the place and I don't know where to start.. any hints/help would be appreciated! Thanks
 

Answers and Replies

  • #2
hage567
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With the information you were given, you can find the initial pressure of the gas.
 
  • #3
Andrew Mason
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I thought of using the equation of work W(by)= 1/(1-gamma) x (PfVf-PiVi) to fnd the answer for a...but I don't have the pressure..:rolleyes:
First work out the initial pressure, which is easy since you are given n,Ti and Vi.
What is the relationship between P and V in an adiabatic expansion/compression? (hint: it involves [itex]\gamma[/itex]). That will give you the final pressure and, if you know n, Vf and Pf you can determine Tf.

AM
 

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