# Homework Help: Thermodynamics problem Help!

1. Jun 20, 2009

### rchenkl

1. The problem statement, all variables and given/known data
Five moles of an ideal monotomic gas initially occupies a volume of 100 x 10-3m3 at a temperature of 280 K. (state 1)
The gas is then subject to the following processes in sequence:
* heated at constant volume to a temperature of 600K (state 2)
* allowed to expand isothermally to its initial pressure (state 3)
* compressed isobarically to its original volume (state 1)

(a) Find the pressure and volume of the gas in state 3
(b) Calculate the work done on the gas in going from state2 to state 3.
(c) Calculate the heat exchanged between the gas and its environment during each of the 3 processes of the cycle 1->2, 2->3, 3->1.
In each case, indicate whether the heat enters or leaves the gas.
(d) Calculate the net work done on the gas in one cycle

2. Relevant equations

PV=nRT=NkBT
pVr=constant, r=Cp/Cv
dW=-PdV
W=nRT*ln(Vi/Vf)
Eint=3/2NkbT
Cv=5/2R

3. The attempt at a solution
I'm stuck on question (a).
I calculated the pressure using PV=nRT where the initial volume, temperature and number of moles of gas is provided. P=(5*8.314*280)/(100x10-3)
Now, I dont know how to calculate the volume in state 3. Do I use T=600K and P=the above I calculated, to obtain the volume?

Last edited: Jun 20, 2009
2. Jun 20, 2009

You got it.