Entropy Question Practice midterm 2013 5B

Boltzmann Equation for Entropy:

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Natalie Yakobian
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Joined: Fri Sep 25, 2015 3:00 am

Entropy Question Practice midterm 2013 5B

Postby Natalie Yakobian » Sat Feb 06, 2016 12:24 pm

Hi,
I am confused with question 5B on the 2013 midterm.
It asks us to put the following substances in increasing order of standard molar entropy
CHF3, CF4, CH3F, CH2F2

I have to conflicting thoughts on this problem.
I understand that heavier molecules have higher molar entropy so CF4 would have the greatest molor entropy,
but if we think about the equation S =klnW, it would seem that CF4 would have the smallest molar entropy because it has only one possible configuration.

Can someone help explain what way we should approach this? Thank you!

stacey
Posts: 7
Joined: Wed Sep 30, 2015 3:00 am

Re: Entropy Question Practice midterm 2013 5B

Postby stacey » Sat Feb 06, 2016 1:17 pm

CH3F<CH2F2<CHF3<CF4. I think it is because F atom is larger than H atom, thus there are more possible states


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