Integral Expression for Work

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

bonnie_schmitz_1F
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Integral Expression for Work

Will we ever need to use the integral equation or do we just need to understand it and be able to apply the variations of it?

Cole Elsner 2J
Posts: 88
Joined: Fri Sep 28, 2018 12:25 am

Re: Integral Expression for Work

The integral equation applies to reversible work, where P is not a constant. Use it if stated to be reversible. Use w=-PdeltaV if it's irreversible.

Posts: 62
Joined: Fri Sep 28, 2018 12:15 am

Re: Integral Expression for Work

You only need to know it to understand the derivation of the 2nd law of thermodynamics. The actual equations used do not include the integral.

Gillian Murphy 2C
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Joined: Fri Sep 28, 2018 12:22 am

Re: Integral Expression for Work

My TA said that the only equations we will have to use for work are w=-PΔV (for a system with constant pressure) and w=-nRT(ln(V2/V1)) (for a reaction that is isothermal reversible). The integral is more for understanding than actual needing to use the equation to solve it for this class (I think)

Eric Quach 1C
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Joined: Fri Sep 28, 2018 12:20 am

Re: Integral Expression for Work

I think we just need to know how to apply it. The integral was used to help explain how the formula w=-PdeltaV was derived.