## Which process does more work?

$w=-P\Delta V$
and
$w=-\int_{V_{1}}^{V_{2}}PdV=-nRTln\frac{V_{2}}{V_{1}}$

Eliza_Beglari_2L
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### Which process does more work?

From Chapter 8 Number 11:
A piston confines 0.200 mol Ne(g) in 1.20 L at 25 degrees C. Two experiments are performed. (a) The gas is allowed to expand through an additional 1.20 L against a constant pressure of 1.00 atm (b) The gas is allowed to expand reversibly and isothermally to the same final volume. Which process does more work?

How do you know which equation to use to compare the two processes?

Jeffrey_Huang_2K
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Joined: Fri Jul 22, 2016 3:00 am

### Re: Which process does more work?

You'll want to calculate the work done by each pathway.
Path A is done at constant pressure so use W=-P*DeltaV (irreversible pathway)
Path B is reversible expansion so use W=-nrT*ln(V2/V1) (reversible pathway)

Timothy_Yu_Dis3A
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### Re: Which process does more work?

The work calculated for a reversible and isothermal pathway is the maximum work possible, therefore it is always a higher value as compared to the work calculated for an irreversible pathway. Real life processes are irreversible, as not all heat is converted to work.

edward_qiao_3I
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### Re: Which process does more work?

So when a question is asking you to consider the difference between reversible or irreversible processes, how can you tell the difference?

AKatukota
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### Re: Which process does more work?

So for the first one, why does the volume remain 1.20L?

Connie Chen 1E
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### Re: Which process does more work?

AKatukota wrote:So for the first one, why does the volume remain 1.20L?

The volume doesn't remain 1.20L, it expands an additional 1.20L.