## Work for an isothermal reversible expansion

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

Sanjana Borle 2K
Posts: 111
Joined: Fri Aug 09, 2019 12:15 am

### Work for an isothermal reversible expansion

For the equation for isothermal reversible expansion, w=-nrTln(V2/V1), are the final temperature, moles, pressure used always?

Fatemah Yacoub 1F
Posts: 114
Joined: Thu Jul 11, 2019 12:16 am

### Re: Work for an isothermal reversible expansion

Pressure is not always used because it is not in the equation, but you can substitute nrt to PV through the ideal gas law.

805373590
Posts: 101
Joined: Wed Sep 11, 2019 12:17 am

### Re: Work for an isothermal reversible expansion

You can use the the ideal gas law to utilize PV instead of nRT in the case that the question only gives you the volume and pressure

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

### Re: Work for an isothermal reversible expansion

In the case of an isothermal reversible expansion, n = number of moles of gas = constant, R = gas constant, and T = constant. By the ideal gas law, since nRT is constant, PV is also constant. It does not matter whether you use the initial or final volume or pressure as their product will be constant.