## Value of R [ENDORSED]

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

Ryan Chang 1C
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Joined: Sat Aug 24, 2019 12:17 am

### Value of R

Why does the value of R has to be altered depending on if the problem gives constant volume or constant pressure?

Chem_Mod
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### Re: Value of R  [ENDORSED]

The gas constant is the same, but it does have different units and therefore different values (which are the same after taking units into account).

I think you are referring to Cv and Cp which are different for gases.
As I discussed in class if a gas is heated and its pressure stays constant, then its volume must increase and therefore does work of expansion (which requires energy).

Unlike Cv, where the gas is heated under a constant volume and therefore does no work.

Therefore, Cv and Cp for gases have different values.

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