Comparing standard molar entropies

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Marni Kahn 1A
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Comparing standard molar entropies

Postby Marni Kahn 1A » Tue Feb 11, 2020 9:02 am

Why do larger, more complex molecules possess larger standard entropies than simpler, smaller molecules in the same phase?

Kassidy Ford 1I
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Re: Comparing standard molar entropies

Postby Kassidy Ford 1I » Tue Feb 11, 2020 4:23 pm

Larger molecules have more particles and therefore have a greater positional entropy value. For example an element with more particles (electrons, protons, and neutrons) (such as Pb vs C) will have a larger degeneracy number, where W=#microstates^(#particles). Then use the equation S=kb(lnW) to solve for entropy

Emma Popescu 1L
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Re: Comparing standard molar entropies

Postby Emma Popescu 1L » Sat Feb 15, 2020 8:37 pm

There are more possible arrangements of atoms for larger, more complex molecules, increasing the number of possible microstates. So the value of W will be larger, thus causing a larger value of S.

Sam McNeill 1E
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Re: Comparing standard molar entropies

Postby Sam McNeill 1E » Tue Feb 18, 2020 10:49 am

You can also think about how larger elements have more electrons, and the possible states that those electrons could occupy contribute to the positional entropy, causing it to have a larger entropy than smaller elements with the less electrons.

Robin Cadd 1D
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Re: Comparing standard molar entropies

Postby Robin Cadd 1D » Tue Feb 18, 2020 11:16 am

Marni Kahn 1A wrote:Why do larger, more complex molecules possess larger standard entropies than simpler, smaller molecules in the same phase?


You could also think of more complex molecules having greater disorder, as there are more particles that make up the molecules (protons, electrons, etc.)

RichBollini4G
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Re: Comparing standard molar entropies

Postby RichBollini4G » Wed Feb 19, 2020 12:03 pm

Kassidy Ford 1I wrote:Larger molecules have more particles and therefore have a greater positional entropy value. For example an element with more particles (electrons, protons, and neutrons) (such as Pb vs C) will have a larger degeneracy number, where W=#microstates^(#particles). Then use the equation S=kb(lnW) to solve for entropy

Thank you

Renee Grange 1I
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Re: Comparing standard molar entropies

Postby Renee Grange 1I » Wed Feb 19, 2020 1:24 pm

More complex molecules have larger standard molar entropies because there are more possible configurations and therefore more disorder, and therefore more entropy than smaller, less complex molecules.


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