Work equation


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Netpheel Wang 4L
Posts: 60
Joined: Fri Sep 28, 2018 12:15 am

Work equation

Postby Netpheel Wang 4L » Mon Feb 04, 2019 12:15 pm

How do you differentiate which work equation to use?

Laura Gong 3H
Posts: 89
Joined: Fri Sep 28, 2018 12:26 am
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Re: Work equation

Postby Laura Gong 3H » Mon Feb 04, 2019 2:44 pm

One is used when the system is at constant pressure (irreversible expansion) (w=-pdeltaV) and the other is used when pressure is not constant (usually isothermal reversible expansion) (w=-nRT*ln(Vf/Vi)).

Samantha Chang 2K
Posts: 69
Joined: Fri Sep 28, 2018 12:17 am

Re: Work equation

Postby Samantha Chang 2K » Mon Feb 04, 2019 3:02 pm

W=-PdeltaV is utilized when pressure IS constant which was shown in lecture through a definite integral because we could factor out the constant of pressure and we are left with the integral dv which just means V2-V1 if we put it into a definite integral. We use the other equation -nRTln(V2/V1) when pressure IS NOT constant, and the derivation of this formula was shown in class today.

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