reversible vs irreversible expansions

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

Elizabeth Bowen 1J
Posts: 53
Joined: Wed Nov 14, 2018 12:20 am

reversible vs irreversible expansions

If we need to calculate the work of expansion of a system, and we're not told whether it's a reversible or irreversible expansion, how do we know which equation should be used?
thanks

AArmellini_1I
Posts: 107
Joined: Fri Aug 09, 2019 12:15 am

Re: reversible vs irreversible expansions

Then it's based on your conditions regarding the system. Is there constant pressure? How about constant temperature? etc.

Elizabeth Bowen 1J
Posts: 53
Joined: Wed Nov 14, 2018 12:20 am

Re: reversible vs irreversible expansions

ok, thanks that makes sense; if we're told that there's not constant pressure, but constant temperature, that means it's reversible, correct?