Work when pressure is constant

isochoric/isometric:
isothermal:
isobaric:

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veneziaramirez 3I
Posts: 57
Joined: Fri Sep 29, 2017 7:07 am

Work when pressure is constant

Postby veneziaramirez 3I » Sun Feb 18, 2018 8:14 pm

When pressure is constant, since w=-P(ext)change in v , it also can be w= -nRT?

Sabah Islam 1G
Posts: 50
Joined: Sat Jul 22, 2017 3:01 am

Re: Work when pressure is constant

Postby Sabah Islam 1G » Sun Feb 18, 2018 8:18 pm

Work can also be w=-nRT because PV=nRT, leading to P(delta V)=(delta n)RT, and you can substitute (delta n)RT into w=-P(delta V).

Emma Li 2C
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Re: Work when pressure is constant

Postby Emma Li 2C » Sun Feb 18, 2018 8:32 pm

Does constant pressure only apply to irreversible reactions?

Niyanta Joshi 1F
Posts: 30
Joined: Thu Jul 13, 2017 3:00 am

Re: Work when pressure is constant

Postby Niyanta Joshi 1F » Sun Feb 18, 2018 8:34 pm

Yes, we can only use W=-P delta V, for a constant external pressure i.e irreversible reaction.

Ridhi Ravichandran 1E
Posts: 35
Joined: Sat Jul 22, 2017 3:01 am

Re: Work when pressure is constant

Postby Ridhi Ravichandran 1E » Sun Feb 18, 2018 8:57 pm

Yes, it can be -nRT. This formula is especially helpful if you don't know the external pressure and only know the net change in the moles of gas.

AlyssaPeckham1A
Posts: 49
Joined: Fri Sep 29, 2017 7:04 am

Re: Work when pressure is constant

Postby AlyssaPeckham1A » Sun Mar 18, 2018 4:14 am

Yes. If pressure is not constant, then we would use w=-nrt ln (v2/v1)

Cassandra Mullen 1E
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Re: Work when pressure is constant

Postby Cassandra Mullen 1E » Sun Mar 18, 2018 9:12 am

If external pressure is given in the problem, then it is irreversible so use w=-P(delta)V


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