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Question: 0.05 kg of gas at 20 bar and 1100⁰C is expanded reversibly to 2 bar by the law PV¹˙³ = C in a closed system.

Determine the initial volume Determine the final volume Calculate the work done.

Provided we can model this gas as ideal then:PV = nRT where n*R = m (m being the mass), the equation being the ideal gas equationThus:V = P/mT = 20*1*10^5 / (0.05 * (1100+273))V = ~29130 m^3To find C we plug in our two values: C = 2000000*29130^1.3 = 1.27 * 10^12To find the final volume we apply the calculation in reverse:(1.27*10^12/200000)^.75 = Vf = 4000m^3As we are not given the degree of freedom of the gas let's say that PV ~ internal energy. Thus work done is the change in PV.W = (delta) PV = 29130*2000000-4000*200000 = ~5.45*10^10 J
01 September 2014
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