### Integral Expression for Work

Posted:

**Wed Feb 06, 2019 5:24 pm**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?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=129&t=41504

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Posted: **Wed Feb 06, 2019 5:24 pm**

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?

Posted: **Wed Feb 06, 2019 5:56 pm**

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.

Posted: **Wed Feb 06, 2019 9:37 pm**

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.

Posted: **Wed Feb 06, 2019 9:43 pm**

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)

Posted: **Thu Feb 07, 2019 10:59 pm**

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.