Which molecule has higher Standard Molar Entropy

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Jade Fosburgh Discussion 2C
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Joined: Fri Sep 29, 2017 7:07 am

Which molecule has higher Standard Molar Entropy

Postby Jade Fosburgh Discussion 2C » Fri Feb 09, 2018 11:47 am

I noticed there were many questions in the homework (#27,29,31) in which we would be given two molecules and were asked which of them was predicted to have a higher molar entropy.

From my interpretation, the trends are as follows. Molecules have a higher molar entropy IF:
-they are more massive
-they are more complex
-gas > liquid > solid
-assuming comparing two gasses with the same # of moles, the gas with less pressure has higher entropy because it will occupy a larger volume
-less rigid structure (more flexible) molecules have higher molar entropy.

However when the topic is revisited in #71, and we are asked to compare benzene, 1 propanol, and methanol, the solutions manual says that 1-propanol is expected to have the highest standard entropy. Why is this?

Swetha Sundaram 1E
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Joined: Fri Sep 29, 2017 7:04 am
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Re: Which molecule has higher Standard Molar Entropy

Postby Swetha Sundaram 1E » Fri Feb 09, 2018 1:25 pm

Both benzene and 1-propanol both have 12 atoms compared to the 6 atoms for methanol. And benzene has a more rigid planar ring structure so 1-propanol has the highest standard molar entropy of all three.


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