## Calculating Work

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

Eileen Si 1G
Posts: 120
Joined: Fri Aug 30, 2019 12:17 am

### Calculating Work

When would you know to use w=-P*delta V versus w=-nRTln(V2/V1) to calculate work of expansion? (Like in homework 4A.5)

Justin Sarquiz 2F
Posts: 106
Joined: Fri Aug 30, 2019 12:15 am

### Re: Calculating Work

Lavelle has not gone over this topic yet because he is starting on thermochemistry first and then going to thermodynamics. I am guessing that you would use the equation according to the information given in the problem.

Sean Cheah 1E
Posts: 105
Joined: Wed Sep 18, 2019 12:20 am

### Re: Calculating Work

Use the first equation for irreversible expansions/contractions occurring against constant external pressure. Use the second equation for reversible expansions where the external pressure is always equal to the internal pressure (pressure of the expanding/contracting gas).