QUIZ one- question 1

Science questions not covered in Chem 14A and 14B. Try to limit questions to chemistry (inorganic chemistry, physical chemistry, organic chemistry, biophysical chemistry, biochemistry, materials science, environmental chemistry).

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Stephanie_Martinez3E
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QUIZ one- question 1

Postby Stephanie_Martinez3E » Wed Feb 08, 2017 9:31 pm

Which molecule, when a single crystal, would you predict to have a larger molar entropy at T=0k; CO or N2? Why?

I know that CO has the larger molar entropy, but I don't understand why? If someone could help me, thanks!

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Re: QUIZ one- question 1

Postby Chem_Mod » Wed Feb 08, 2017 9:36 pm

CO has more molecular arrangements since the two atoms are different.

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Re: QUIZ one- question 1

Postby Chem_Mod » Wed Feb 08, 2017 9:38 pm

At T = 0 K there is no thermal energy to contribute to entropy in terms of molecular motion, rotation, vibration, etc.

However, several different configurations of the molecules in the crystal could be "frozen in" at T = 0 K depending on how many ways each could be oriented.

CO can be arranged in more distinct ways (more microstates) than N2 because of the asymmetry of CO across the bond vs. the symmetry N2.

C-O
or
O-C

vs.

N-N <-- only one way


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