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Helium gas expands from 350 K, 125 kPa and 0.25 m^3 to 100 kPa in a polytropic process with n = 1.667. How much work does it give out?

Helium gas expands from 350 K, 125 kPa and 0.25 m^3 to 100 kPa in a polytropic process with n = 1.667. How much work does it give out? Correct Answer 4.09 kJ

Process: PV^n = constant = P1(V1)^n = P2(V2)^n V2 = V1 (P1/P2)^(1/n) = 0.25 × (125/100)^(0.6) = 0.2852 m^3 Work = (P2V2 – P1V1)/(1-n) = (100× 0.2852 – 125× 0.25)/(1 – 1.667) = 4.09 kJ.

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