Reversible vs Irreversible


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Melodie Oh 2A
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Reversible vs Irreversible

Postby Melodie Oh 2A » Mon Jan 29, 2018 5:37 pm

I read the textbook and I still don't really understand the concept of reversible and irreversible expansion. What exactly are the difference between the two in terms of the work??

Alyssa Pelak 1J
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Re: Reversible vs Irreversible

Postby Alyssa Pelak 1J » Mon Jan 29, 2018 5:52 pm

Reversible reactions are at equilibrium meaning that they are slow. They occur when P is not constant, so the equation, w=-nRTln(V^2/V^1), is used. More work is done because these systems have to work on equilibrium.

Irreversibly reactions are fast and take less work. These reactions occur a constant P and the equation, w=-P(delta V), is used.

Ryan Sydney Beyer 2B
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Re: Reversible vs Irreversible

Postby Ryan Sydney Beyer 2B » Mon Jan 29, 2018 6:37 pm

A reversible reaction means that the system and the surroundings can be restored to the initial state from the final state without changing any thermodynamic properties. There are two main conditions for the reversible process to occur. 1) the process should occur in infinitesimally small increments of time and 2) all of the initial state and final state should be in equilibrium with each other.

An irreversible process occurs due to the finite difference between two states of a system. Some important things to note about irreversible systems 1) the initial state of the system and surroundings cannot be restored from the final state (can't go backwards) 2) During the process, the various states of the system are not in equilibrium with each other 3) the entropy of the system increases and cannot be reduced back to it's original value.

Salma Quintanilla 1J
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Re: Reversible vs Irreversible

Postby Salma Quintanilla 1J » Mon Jan 29, 2018 6:48 pm

Reversible expansion is one that can be reversed by an infinitely small change in a variable. An example of this at work would be when a gas expands reversibly, the pressure on the outside is matched to the pressure of the gas during the expansion. This example could be directed in either direction, whether the piston for example moves in or out. An irreversible process is expansion against an external pressure that differs by a finite amount from the pressure of the system.

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Re: Reversible vs Irreversible

Postby allyz1F » Sat Feb 10, 2018 4:20 pm

Just for clarification, is this why reversible expansion work is always greater in quantity than irreversible expansion? Because it responds to any infinitesimal change in a variable? Makes sense because if work is constantly changing from any variable affecting the system, there would be a greater quantity of work, but I just want to make sure I'm understanding this right.

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