$\Delta U=q+w$

kshalbi
Posts: 68
Joined: Fri Sep 25, 2015 3:00 am

If a gas expands adiabatically and you have to find the work it does, do you use the equation for reversible or irreversible reactions?

Chem_Mod
Posts: 19138
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 820 times

No, you would not use the isothermal equations. The work done would be equal to the internal energy change since U=q+w but q=0 for adiabatic. So all you need to know is the initial and final temperatures to find deltaU then that is also w.

kshalbi
Posts: 68
Joined: Fri Sep 25, 2015 3:00 am

Yeah but then to find w do you use: -PdeltaV or the -nRTln (v1/v2). These two equations are what I meant by the "reversible or irreversible" equations for work.

kshalbi
Posts: 68
Joined: Fri Sep 25, 2015 3:00 am

Yeah but then to find w do you use: -PdeltaV or the -nRTln (v1/v2). These two equations are what I meant by the "reversible or irreversible" equations for work.

Alan Chien 1J
Posts: 72
Joined: Fri Sep 25, 2015 3:00 am