### Integral calculations

Posted:

**Mon Feb 04, 2019 12:58 am**When do you know to take the integral when finding work?

Created by Dr. Laurence Lavelle

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

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=129&t=41339

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Posted: **Mon Feb 04, 2019 12:58 am**

When do you know to take the integral when finding work?

Posted: **Mon Feb 04, 2019 9:18 am**

I think we just took the integral of the graph of external pressure and volume in order to derive the equation for work at constant pressure for irreversible expansion. I think as long as you can recognize the conditions at which you use w = -Pex (deltaV), you don't need to take any integrals.

Posted: **Mon Feb 04, 2019 9:38 am**

I don't think we will have to take an integral. Dr. Lavelle was only deriving the formula for work done by reversible expansion. We will get to this formula in class later, I believe.

Posted: **Mon Feb 04, 2019 9:48 am**

Since our integral is of integral of P with respect to dV, we are integrating a constant. So our difference is of the difference of V, which is why we aren't necessarily taking an *actual* integral.

In essence, we are doing the integral through using the formula of -P* delta V.

(This is all based off the work by expansion)

In essence, we are doing the integral through using the formula of -P* delta V.

(This is all based off the work by expansion)

Posted: **Mon Feb 04, 2019 10:02 am**

I do not think we will be required to know how to take an integral. Lavelle was just showing us where the equation was derived from!