8.3 Reversible Isothermal Expansion

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OliviaShearin2E
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Joined: Fri Sep 29, 2017 7:05 am

8.3 Reversible Isothermal Expansion

Postby OliviaShearin2E » Mon Jan 08, 2018 4:04 pm

8.3 describes, "In an isothermal expansion, the pressure of the gas falls as it expands (by Boyle’s law); so, to achieve reversible expansion, the external pressure must be reduced in step with the change in volume so that at every stage the external pressure is the same as the pressure of the gas." Should we assume reducing the external pressure is part of the theoretical experimental process in order to maintain the reversibility of the system?

Yashaswi Dis 1K
Posts: 56
Joined: Fri Sep 29, 2017 7:04 am

Re: 8.3 Reversible Isothermal Expansion

Postby Yashaswi Dis 1K » Mon Jan 08, 2018 8:35 pm

Hi,

I think you brought up a good point. I am a bit confused by your question but I think what they are saying essentially is during a reversible process, a system is in thermodynamic equilibrium with its surroundings. So for every reduction in external pressure, the volume usually changes infinitesimally to combat the external pressure so that the only pressure is due to the gas...at least that's my idea on what the textbook is saying as per the quote you cited.

RyanTran2F
Posts: 44
Joined: Thu Jul 27, 2017 3:00 am

Re: 8.3 Reversible Isothermal Expansion

Postby RyanTran2F » Mon Jan 08, 2018 9:45 pm

I agree with Yashaswi's answer. A reversible process is a process that can be reversed as a result of an infinitely small change. If the external pressure is increased one bit, the volume will decrease and vice versa.

Veritas Kim 2L
Posts: 30
Joined: Fri Sep 29, 2017 7:05 am

Re: 8.3 Reversible Isothermal Expansion

Postby Veritas Kim 2L » Thu Jan 11, 2018 11:34 pm

Yes. I think that in order to maintain reversible process during gas expansion, the external pressure has to match the pressure of the gas at every stage of the expansion and reach the maximum work since even an infinitely small change makes it reversible.


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