A pistoncylinder device initially contains 020 kg of nitroge

A piston-cylinder device initially contains 0.20 kg of nitrogen gas at 125 kPa and 135 degree C. The nitrogen is now expand isothermally to a pressure of 94 kPa. Determine the boundary work done during this process.

Solution

>> P1 = Initial Pressure = 125 kPa

>> P2 = Final Pressure = 94 kPa

>> m = mass of Gas = 0.20 kg

>> T = Temperature of system = 135° C = 408 K

>> As, Process is Isothermal. So, Temperature will remain constant.

>> As, Work Done in an Isothermal Process, W = mRT*ln(P1/P2)

R = Gas Constant for Nitrogen Gas = 8.314/28 = 0.297

>> Putting all values in above Equation,

W = mRT*ln(P1/P2)

=> W = 0.20*0.297*408*ln(125/94)

=> Required Work Done = 6.90 KJ