## Work when pressure is constant

isochoric/isometric: $\Delta V = 0$
isothermal: $\Delta T = 0$
isobaric: $\Delta P = 0$

veneziaramirez 3I
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### Work when pressure is constant

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

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

### Re: Work when pressure is constant

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

Does constant pressure only apply to irreversible reactions?

Niyanta Joshi 1F
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### Re: Work when pressure is constant

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

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

### Re: Work when pressure is constant

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
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### Re: Work when pressure is constant

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

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

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