Polytropic Process: Finding Final Pressure and Volume

AI Thread Summary
The discussion focuses on a polytropic process involving hydrogen gas in a piston-cylinder setup. The initial conditions include a pressure of 100 kPa, temperature of 765°C, and a volume of 0.35 m³, with a final volume of 8.0 m³ after the process. Participants clarify that the relevant equation for this process is PV^n = constant, allowing for the calculation of final pressure and volume. The mass of the gas has been determined, and the final pressure has been calculated, but there is confusion regarding the final volume. The key takeaway is the application of the polytropic equation to find the necessary values.
Mohd17
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Homework Statement



A frictionless piston cylinder contains ideal gas hydrogen , R = 4.125 KJ/Kg.K , initially at p1=100 Kpa , t1 = 765 C , V1 = 0.35 m3 . The gas undergoes a polytropic process with n = 1.22 until the final volume becomes V2=8.0 m3

Cp = 14.3338 , Cv= 10.2043 , [URL]http://www.taftan.com/thermodynamics/GAMMA.GIF[/URL] = 1.4

Find :
a) Mass of the ideal gas
b) Final pressure and volume of the gas
 
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You need to post your attempt.

What relevant equations do you think are needed here?
 
the problem how can i get the volume of the gas !

already i get the answers for part a and the final pressure
 
Mohd17 said:
the problem how can i get the volume of the gas !

already i get the answers for part a and the final pressure

You should know for a polytropic process PVn = constant.
 
sorry but i didin't understand ...
now what's the answer ?
 
Mohd17 said:
sorry but i didin't understand ...
now what's the answer ?

PVn = constant means that

P1V1n = P2V2n

You were given P1, V1, n and you found P2.
 

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