## Integral calculations

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

Posts: 62
Joined: Fri Sep 28, 2018 12:26 am

### Integral calculations

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

Elizabeth Gallmeister 1A
Posts: 41
Joined: Fri Sep 28, 2018 12:21 am

### Re: Integral calculations

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.

Jayasuriya Senthilvelan 4I
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Joined: Thu Jan 10, 2019 12:17 am

### Re: Integral calculations

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.

deepto_mizan1H
Posts: 65
Joined: Fri Sep 28, 2018 12:16 am

### Re: Integral calculations

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)

Kaylee Kang 1G
Posts: 65
Joined: Fri Sep 28, 2018 12:24 am

### Re: Integral calculations

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!