5/2R vs 3/2R

[Briana Yik 1H]

how do we know when to use 5/2R versus 3/2R?

[lizettelopez1F]

Cp=5/2r is used when you need to find the heat capacity of an ideal gas with a constant pressure. Cv=3/2R is used when you need to find the heat capacity of an ideal gas with a constant volume

[KatrinaPho_2I]

These values only work if you are dealing with monoatomic ideal gases.

[abbydouglas1K]

If the question says that the pressure is being kept constant(Cp) or that the volume is being kept constant (Cv) you will use 5/2R and 3/2R respectively if the molecule in question is a monatomic gas.

[Christopher Anisi 2K]

For a monoatomic gas under a constant pressure the Cp value is equal to 5/2R however if it is under a constant volume the Cv value is equal to 3/2R.