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## Main Question or Discussion Point

I know that the translational energy of gas can be represented by

3/2NkT

where N = number of molecules, k = boltzmann's constant, T = temperature

my textbook says that the change in entropy is

(delta)S = (integral from 1 to 2) dS = (integral from 1 to 2) dU/T + (integral from 1 to 2) PdV/T = NRln(v2/v1)

i know that since U = 0 in an isothermal system, dU/T term gets cancelled and the PdV/T term is left, but i don't understand how we get NRln(v2/v1) from it

i also dont know how translational energy comes in to place.

much help needed!

3/2NkT

where N = number of molecules, k = boltzmann's constant, T = temperature

my textbook says that the change in entropy is

(delta)S = (integral from 1 to 2) dS = (integral from 1 to 2) dU/T + (integral from 1 to 2) PdV/T = NRln(v2/v1)

i know that since U = 0 in an isothermal system, dU/T term gets cancelled and the PdV/T term is left, but i don't understand how we get NRln(v2/v1) from it

i also dont know how translational energy comes in to place.

much help needed!