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- This is a thread I am posting to help members understand how to calculate entropy change in irreversible adiabatic processes

I have an ideal gas in a cylinder with a massless, frictionless piston, and the gas starts out at To, Po, Vo. The system is adiabatic. Initially, the gas is in equilibrium with an external pressure, also at Po. I initiate an irreversible process by instantly dropping the external pressure to P1, and hold this pressure constant while the gas expands and equilibrates with the new external pressure P1 at a new volume and temperate V1 and T1.

(a) Based on the 1st law of thermodynamics and the ideal gas law, what at the values of the new volume and temperature (in terms of Po, To, Vo, and P1)? How much irreversible work was done? What was the change in U?

(b) Describe at least 2 reversible process you have devised to transition from the same initial state to the same final state. How much work was done, how much heat was added in each, and what was the change in U for these reversible processes?

(c). What was the change in entropy for the reversible processes? What was the change in entropy of the irreversible process?

(a) Based on the 1st law of thermodynamics and the ideal gas law, what at the values of the new volume and temperature (in terms of Po, To, Vo, and P1)? How much irreversible work was done? What was the change in U?

(b) Describe at least 2 reversible process you have devised to transition from the same initial state to the same final state. How much work was done, how much heat was added in each, and what was the change in U for these reversible processes?

(c). What was the change in entropy for the reversible processes? What was the change in entropy of the irreversible process?

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