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### Formula for isothermal, reversible equilibrium

Posted: Mon Feb 03, 2020 10:19 am
For isothermal reversible reactions, do we always use the equation w=-nRT ln (v1/v2)?
And so I assume for irreversible equation we can use P delta V?

### Re: Formula for isothermal, reversible equilibrium

Posted: Mon Feb 03, 2020 10:23 am
Correct! Just remember work = -Pdeltav.

### Re: Formula for isothermal, reversible equilibrium

Posted: Mon Feb 03, 2020 10:25 am
When using the equation -nRTln(V2/V1) for reversible reactions, does n stand for the change in moles after the reaction takes place or does it stand for the total number of moles?

### Re: Formula for isothermal, reversible equilibrium

Posted: Mon Feb 03, 2020 12:32 pm
Brian Tangsombatvisit 1C wrote:When using the equation -nRTln(V2/V1) for reversible reactions, does n stand for the change in moles after the reaction takes place or does it stand for the total number of moles?

I believe n stands for the net amount of moles produced in the reaction (so final amount of moles-initial moles).

### Re: Formula for isothermal, reversible equilibrium

Posted: Tue Feb 04, 2020 10:03 pm
Yeah, for reversible expansion, the equation for work is w=-nRTln(v2/v1) and for irreversible expansion, the equation is w=-PexdeltaV. They are both essentially the same, except the irreversible expansion has constant pressure, while reversible expansion has change in pressure.