ΔS = nRln(v2/v1)

Volume:
Temperature:

Moderators: Chem_Mod, Chem_Admin

Philip Lee 1L
Posts: 30
Joined: Fri Sep 28, 2018 12:21 am

ΔS = nRln(v2/v1)

Postby Philip Lee 1L » Sat Feb 09, 2019 12:31 am

During lecture, an equation for ΔS was derived using a previously given equation that relates entropy with degeneracy. The steps are as follows:

Given: S = kBlnW

1) ΔS = Sfinal - Sinitial

2) ΔS = kBlnW2 - kBlnW1

3) ΔS = kBln(W2/W1)

4) ΔS = kBln(V2/V1)

5) ΔS = nRln(V2/V1)

I am not sure how you get from step 4 to step 5. I know that the Boltzmann constant, kB = R/NA.
Why does kB get replaced with nR?

Anushi Patel 1J
Posts: 61
Joined: Fri Sep 28, 2018 12:19 am
Been upvoted: 1 time

Re: ΔS = nRln(v2/v1)

Postby Anushi Patel 1J » Sat Feb 09, 2019 10:07 am

I'm not sure, but I think it's because R is equal to kb multiplied by NA. Since the NA is actually the exponent within the natural log, you can take it out of the natural log and multiply it with Kb, which is equal to R. The n comes from the fact that since we used Avagadro's number we are calculating the entropy per mole, so we need to multiply it by the number of moles.


Return to “Entropy Changes Due to Changes in Volume and Temperature”

Who is online

Users browsing this forum: No registered users and 1 guest