S and delta S

Boltzmann Equation for Entropy:

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Amanda Mac 1C
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Joined: Fri Sep 29, 2017 7:05 am

S and delta S

Postby Amanda Mac 1C » Fri Mar 16, 2018 9:00 pm

Can someone tell me the difference between S (like in the Boltzmann equation) and delta S besides the fact that delta S is the change in entropy? How would we find S?

Michaela Capps 1l
Posts: 50
Joined: Thu Jul 27, 2017 3:00 am

Re: S and delta S

Postby Michaela Capps 1l » Fri Mar 16, 2018 9:03 pm

S is the residual entropy while delta S is the change in entropy.

Julia Cheng 2J
Posts: 31
Joined: Thu Jul 13, 2017 3:00 am

Re: S and delta S

Postby Julia Cheng 2J » Sat Mar 17, 2018 1:17 pm

You would usually use delta S to find the change in entropy of a reaction (so some change to the system has to happen in order for there to be a delta S). We've only been using S to find the entropy of a molecule as a result of its structure (so there doesn't have to be any change in its state).

Lisa Tang 1C
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Re: S and delta S

Postby Lisa Tang 1C » Sat Mar 17, 2018 1:41 pm

You can find the absolute entropy by using the Boltzmann equation S=kB*lnW. kB is Boltzmann's constant (1.38x10-23J/K).

YashDeshmukh1D
Posts: 42
Joined: Fri Sep 29, 2017 7:05 am

Re: S and delta S

Postby YashDeshmukh1D » Sat Mar 17, 2018 3:20 pm

S as described by the Boltzmann equation describes positional entropy. That is, the total entropy or disorder as a result of the orientations of the molecules, rather than their thermal entropy, which is determined by their motion. Delta S usually combines both these quantities to describe how entropy changes over the course of a reaction.


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