Clarification on an explanation during the lecture

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Ernie Lee 3F
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Joined: Mon Jan 09, 2023 10:04 am

Clarification on an explanation during the lecture

Postby Ernie Lee 3F » Mon Feb 06, 2023 4:04 pm

Hello, when Professor Lavelle mentioned Thermodynamical property ("Small" error in S) and Statistical property ("Large" error in W), was it to explain that even with a large W value, there won't be a significant change in S?

Gregory_Kislik_2C
Posts: 47
Joined: Mon Jan 09, 2023 8:57 am

Re: Clarification on an explanation during the lecture

Postby Gregory_Kislik_2C » Mon Feb 06, 2023 9:05 pm

Yes. Because of the ln in the equation deltaS = kblnW, large changes in W will result in small changes in S, so the relative uncertainty is small in S despite it being large in W.

For example, take a sample of five particles of BF2Cl, which has three possible positions. The resulting number of microstates is 3^5, or 243 = W.

Entropy however, turns that 3^5 into a 5ln3 (multiplied by the Boltzmann constant), which makes it a much smaller number.

I hope this helps, please let me know if there are any errors.


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