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**[thermodynamics] "Is it possible" problem.**

Air in a piston-cylinder device, heat input

Initially: T1 = 21Celsius, P1 = 2 atm

Finally: T2 = 38Celsius, P2 = 2 atm = P1 (isobaric)

Heat source: TH = 260Celsius, qH = 23 kJ/kg (heat input)

Find:

a) specific work output, w =?

b) whether the process is possible?

Illustration figure can be found here:

hxxp://img247.imageshack.us/img247/4540/tempca1.jpg

The process have a positive total entropy change but the professor said it is impossible, positive total entropy change is true but still something missing, anyone know what is it?