W for BFCl2 in the lecture example

Boltzmann Equation for Entropy:

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Yutian Zhao -1J
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W for BFCl2 in the lecture example

Postby Yutian Zhao -1J » Mon Jan 22, 2018 2:58 pm

in the lecture, for the last example to calculate the W of BFCl2, if there are four moles of this molecules, does that mean w= 3^4NA? and therefore S=4Rln3? I am a little bit confused. Thanks!

Ammar Amjad 1L
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Re: W for BFCl2 in the lecture example

Postby Ammar Amjad 1L » Mon Jan 22, 2018 4:41 pm

It would be 3^4A, because you need to consider the shape of the molecule. It's trigonal planar so there are three different places the atoms can bound to; therefore your equation would be 3^NA. The question states in the beginning that there are 4 moles of this molecule; therefore it's 3^4A. S= Kb ln(w), and in this particular problem S= Kb ln(3^4A), you can bring out the 4A because of log properties to make it S= 4AKb ln(3). In lecture Dr. Lavelle said that when you multiply Avogadro's constant with Boltzmann's constant you get R; therefore, the equation becomes S= 4R ln(3).

Hope this helps.


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