## Entropy changes

Volume: $\Delta S = nR\ln \frac{V_{2}}{V_{1}}$
Temperature: $\Delta S = nC\ln \frac{T_{2}}{T_{1}}$

JukaKim_1D
Posts: 24
Joined: Fri Sep 25, 2015 3:00 am

### Entropy changes

Why is it that when calculating for entropy change delta S is equal to either nRlnV2/V1 or nClnT2/T1 but when using pressure, it is nRlnP1/P2?

Nathan Danielsen 1G
Posts: 17
Joined: Fri Sep 25, 2015 3:00 am

### Re: Entropy changes

According to the noble gas equation, PV=nRT, pressure is the inverse of volume, all other things being held constant. Since those equations for entropy are derived from the noble gas equation, using P1/P2 will give you the correct value.

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