Value of R  [ENDORSED]


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Ryan Chang 1C
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Value of R

Postby Ryan Chang 1C » Mon Feb 03, 2020 6:27 pm

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

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Re: Value of R  [ENDORSED]

Postby Chem_Mod » Tue Feb 04, 2020 11:58 am

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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