A piston cylinder containing Ar at some initial temperature(To), is allowed to c

Question

A piston cylinder containing Ar at some initial temperature(To), is allowed to cool. Once the volume of the cylinder collapses to V1 = 0.06 m^3, stops inhibit further reduction of volume. The cylinder is in an environment of 101.35 kPa and 298 K.

a) How much heat [Q] nad work [W] is lost to the surroundings if Vo = 0.15 m^3 and T1 = 650 K. Assume constant specific heats.

b) Repeat part A using variable specific heats Cp = [Cp(To) + Cp(T1)]/2  & Cv = [Cv(To) + Cv(T1)]/2

c) What is the final state of the Ar in the container? Pf, Tf, vf, Vf

Explanation / Answer

a) W=P(V1-V0)=101.35*(0.06- 0.15 )=-9.1215 kJ

n=p1V1/RT1=(101.35*10^3*0.06)/(8.314*298)=2.45 moles

Cp=kR/k-1=1.4*8.314/0.4=29.09 J/moleK

Q= nCp(T1-T0)= 2.45*29.09*(298- 650)=-25087.216 J

c)

Pf=101.35 kPa

Tf=298 K

Vf= 0.06m^3

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