How Do You Calculate State Changes in a Monatomic Gas Thermodynamic Cycle?

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SUMMARY

The discussion focuses on calculating state changes in a monatomic ideal gas during a thermodynamic cycle involving five moles of gas. The initial conditions include a volume of 100 x 10-3 m3 and a temperature of 280 K. Key calculations involve determining the pressure and volume in state 3 using the ideal gas law (PV=nRT), as well as calculating work done during transitions and heat exchanged in each process. The user successfully calculated the initial pressure and seeks guidance on finding the volume in state 3.

PREREQUISITES
  • Understanding of the Ideal Gas Law (PV=nRT)
  • Knowledge of thermodynamic processes (isothermal, isobaric, constant volume)
  • Familiarity with concepts of work and heat transfer in thermodynamics
  • Basic understanding of monatomic gas properties and equations (e.g., Eint=3/2NkbT)
NEXT STEPS
  • Calculate the volume in state 3 using the ideal gas law with the known pressure from state 2.
  • Learn about the first law of thermodynamics to understand energy conservation in cycles.
  • Explore the derivation and application of the work done formula W=nRT*ln(Vi/Vf) in isothermal processes.
  • Investigate heat capacity ratios (Cp/Cv) and their implications in thermodynamic cycles.
USEFUL FOR

Students studying thermodynamics, physics enthusiasts, and professionals in engineering fields focusing on gas laws and energy transfer processes.

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Homework Statement


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

Homework Equations



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

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 don't 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:
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