Reversible vs irreversible


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Jeremiah Hutauruk
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Joined: Fri Sep 28, 2018 12:28 am

Reversible vs irreversible

Postby Jeremiah Hutauruk » Wed Feb 13, 2019 4:23 pm

Does w=-PdeltaV only work when there is constant pressure and when the reaction is irreversible?

Chem_Mod
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Re: Reversible vs irreversible

Postby Chem_Mod » Wed Feb 13, 2019 4:32 pm

That is correct.

Cameron_Greenberg_3C
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Re: Reversible vs irreversible

Postby Cameron_Greenberg_3C » Sat Feb 16, 2019 10:33 pm

In addition, a reversible reaction will instead have the equation w=-nrTln(V2/V1).

KimGiang2F
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Joined: Fri Sep 28, 2018 12:19 am

Re: Reversible vs irreversible

Postby KimGiang2F » Tue Mar 12, 2019 3:48 am

When there is constant pressure and the reaction is irreversible, the equation w=-Pex∆V is derived from P=F/A, in which to find the force of the equation you can use the relationship and get F=PexA. The work needed to drive the piston out through a distance d is, therefore, work= PexA •d (work=force•distance). From volume = area • height, it can be assumed that the product of area and distance moved is equal to the change in volume of the sample (A•d=∆V). So to get the final equation, you can replace A•d in the work equation with ∆V, resulting in w=-Pex∆V. The resulting equation is negative as when a system expands, it loses energy as work. Therefore, if ∆V is positive, w is negative.

Samantha Chang 2K
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Re: Reversible vs irreversible

Postby Samantha Chang 2K » Tue Mar 12, 2019 10:23 am

Yes, and remember that an irreversible reaction will always require less work.

Bianca Barcelo 4I
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Re: Reversible vs irreversible

Postby Bianca Barcelo 4I » Wed Mar 13, 2019 2:56 am

Will reversible expansion always do more work?

Ian Marquez 2K
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Re: Reversible vs irreversible

Postby Ian Marquez 2K » Wed Mar 13, 2019 3:22 pm

Reversible expansion will always do more work. It is also clear to make this distinction by looking at some of the graphs and the area underneath the curve when comparing reversible and irreversible expansion.


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