Free expansion


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Free expansion

Postby manasa933 » Fri Feb 02, 2018 2:54 pm

If q=0, and work is different in two conditions (one of which is free expansion and the other one isn't), then U will be different in both cases. Isn't this against the statement that U is a state function?

Jenny Cheng 2K
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Re: Free expansion

Postby Jenny Cheng 2K » Fri Feb 02, 2018 8:44 pm

No work is done in free expansion because there is no external pressure; for example, free expansion occurs when a gas pushes against a piston and expands into a vacuum (in which no work is done). For a gas that is expanding by pushing against a piston and an external pressure (no free expansion), there is work done. For internal energy, you are still looking at the final and initial conditions of the system. I think it's important to consider the conditions of the system.

Magdalena Palavecino 1A
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Re: Free expansion

Postby Magdalena Palavecino 1A » Sat Feb 10, 2018 1:22 pm

So no work is done but there still is a change in internal energy due to the change in volume?

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