Irreversible and Reversible Expansion

Boltzmann Equation for Entropy:

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Bianca Barcelo 4I
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Joined: Fri Sep 28, 2018 12:17 am
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Irreversible and Reversible Expansion

Postby Bianca Barcelo 4I » Tue Feb 12, 2019 1:12 am

How does irreversible and reversible expansion work? What is happening conceptually with the gas and when is pressure constant?

Emmaraf 1K
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Joined: Sat Oct 20, 2018 12:16 am

Re: Irreversible and Reversible Expansion

Postby Emmaraf 1K » Tue Feb 12, 2019 10:01 am

In irreversible expansion, the outer pressure will suddenly drop from say 2 to 1 ATM and so the piston will constantly be pushing against 1 ATM of pressure. In reversible expansion, the pressure outside slowly drops bit by bit from 2 to 1.9 to 1.8 to 1.7 (not actually by .1 but by an infitesimally small amount) so the piston is pressing against a little bit less pressure each time. The reversible expansion does more work because it doesn't press by 1 ATM constantly but by 1.9 to 1.8 to 1.7 (again not exact values) and so on and so forth.

Patrick Cai 1L
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Joined: Fri Sep 28, 2018 12:25 am

Re: Irreversible and Reversible Expansion

Postby Patrick Cai 1L » Tue Feb 12, 2019 10:16 am

Reversible can be thought of as if the system and surroundings are at equilibrium, where any change in volume can be seen as a infinitesimally close to the original thermodynamic state; irreversible tends towards one direction and no small change can restore initial conditions.

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