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3/2R vs 5/2R

Posted: Wed Feb 13, 2019 12:05 am
by Lisa Werner 2F
how can we tell when to use 3/2R and 5/2R as C?

Re: 3/2R vs 5/2R

Posted: Wed Feb 13, 2019 12:30 am
by Gillian Murphy 2C
3/2R is used when it is at constant volume for a monoatomic ideal gas
5/2R is used when it is at constant pressure for a monoatomic ideal gas

Re: 3/2R vs 5/2R

Posted: Thu Feb 14, 2019 5:08 pm
by Kirsty Star 2H
Agreed. You know which one to use in the context of the problem, so it's important to identify what is being held constant in the given problem

Re: 3/2R vs 5/2R

Posted: Thu Feb 14, 2019 8:39 pm
by Zubair Ahmed 1L
It is very important to know the difference between. 5/2R is used for constant pressure and 3/2R is used for constant volume. You will have to use either one depending on the context of the question.

Re: 3/2R vs 5/2R

Posted: Thu Feb 14, 2019 9:26 pm
by MadelineHlobik
Is (3/2 R) the same as Cn when you are trying the change in entropy when there is a temperature difference?

Re: 3/2R vs 5/2R

Posted: Fri Feb 15, 2019 2:05 pm
by Jason Ye 2I
When it is constant pressure or constant volume. Or based on the shape of the molecules.

Re: 3/2R vs 5/2R

Posted: Fri Feb 15, 2019 2:39 pm
by Soumya Ravichandran 4H
3/2 R is used for Cv of an ideal monoatomic atom. 5/2R is for Cv of a linear molecule and for Cp of an ideal monoatomic atom.

Re: 3/2R vs 5/2R

Posted: Sat Feb 16, 2019 9:06 pm
by Ashe Chen 2C
3/2 R is used for a monoatomic ideal gas at constant volume where 5/2 R is used is used for a monoatomic gas at constant pressure, or for a linear molecule at constant volume.

Re: 3/2R vs 5/2R

Posted: Sat Feb 16, 2019 9:48 pm
by Cameron_Greenberg_3C
In addition to the other answers, the heat capacity at constant volume and the heat capacity at constant temperature are always separated by a factor of R. (C)v,m = R + (C)p,m. So, for single atoms 3/2R is the (C)v,m and 5/2R is the (C)P,m, while linear atoms have a (C)v,m of 5/2R, and more complicated molecules have a (C)v,m of 3R.