Standard Molar Entropy Question

Moderators: Chem_Mod, Chem_Admin

Ryan Sydney Beyer 2B
Posts: 82
Joined: Fri Sep 29, 2017 7:07 am
Been upvoted: 1 time

Standard Molar Entropy Question

Postby Ryan Sydney Beyer 2B » Tue Feb 13, 2018 7:42 pm

Arrange the following in order of increasing standard molar entropy: CHF3, CF4, CH3F, CH2F2

(all are in the gaseous phase)

The correct answer has CH3F < CH2F2 < CHF3 < CF4 but shouldn't have a higher standard molar entropy then since there are more ways to orientate the molecules?

Curtis Wong 2D
Posts: 62
Joined: Sat Jul 22, 2017 3:00 am

Re: Standard Molar Entropy Question

Postby Curtis Wong 2D » Tue Feb 13, 2018 9:54 pm

Remember that entropy also depends on the complexity of the molecule itself, so that also means the elements that it consists of. So in this case, F is more complex than H in terms of its atomic structure. It has more particles in its atom than H and each of those particles has more orientations possible. SO that's why CF4 has the highest entropy.

Helen Shi 1J
Posts: 78
Joined: Sat Jul 22, 2017 3:00 am

Re: Standard Molar Entropy Question

Postby Helen Shi 1J » Tue Feb 13, 2018 10:03 pm

So the complexity of the molecule overrules positional disorder?

Nancy Dinh 2J
Posts: 59
Joined: Fri Sep 29, 2017 7:07 am

Re: Standard Molar Entropy Question

Postby Nancy Dinh 2J » Tue Feb 13, 2018 11:56 pm

Helen Shi 1J wrote:So the complexity of the molecule overrules positional disorder?


I think so. As far as my memory goes, I've only seen positional disorder come to play when T=0K.


Return to “Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)”

Who is online

Users browsing this forum: No registered users and 1 guest