## Formula for isothermal, reversible equilibrium

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

KNguyen_1I
Posts: 101
Joined: Sat Aug 17, 2019 12:16 am

### Formula for isothermal, reversible equilibrium

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?

Posts: 113
Joined: Thu Jul 11, 2019 12:16 am

### Re: Formula for isothermal, reversible equilibrium

Correct! Just remember work = -Pdeltav.

Brian Tangsombatvisit 1C
Posts: 119
Joined: Sat Aug 17, 2019 12:15 am

### Re: Formula for isothermal, reversible equilibrium

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?

sarahforman_Dis2I
Posts: 109
Joined: Sat Aug 17, 2019 12:18 am

### Re: Formula for isothermal, reversible equilibrium

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).

Verity Lai 2K
Posts: 100
Joined: Sat Aug 24, 2019 12:18 am

### Re: Formula for isothermal, reversible equilibrium

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.