Boiling point

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Gisela F Ramirez 2H
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Joined: Fri Sep 28, 2018 12:27 am

Boiling point

Postby Gisela F Ramirez 2H » Sun Dec 09, 2018 3:46 am

Between H2S and H2Se, explain why H2Se has a higher boiling point.
In this case, even though H2S has dipole-dipole forces, H2Se has stronger LDFs. Why do the LDF dominate dipole dipole forces when dipole dipoles are stronger?

Emily Kennedy 4L
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Re: Boiling point

Postby Emily Kennedy 4L » Sun Dec 09, 2018 9:24 am

less distorted electron cloud that is larger

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Re: Boiling point

Postby Rami_Z_AbuQubo_2K » Sun Dec 09, 2018 5:04 pm

Since the difference in electronegativity between Se and S is negligible, we are considering their dipoles as almost the same. The only thing we can look at now is london forces and since Se is bigger, it is going to create a bigger temporary dipole and have stronger london forces.

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Re: Boiling point

Postby 305113590 » Sun Dec 09, 2018 5:59 pm

To add, boiling point can also increase with increased surface area, molecular weight, and amount of London Dispersion forces there are. More condensed and bunched up lewis structures contribute to lower boiling points than ones that are more spread out in a hydrocarbon chain.

Nathan Tran 4K
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Re: Boiling point

Postby Nathan Tran 4K » Sun Dec 09, 2018 6:05 pm

In this question, it is specified that H2Se has a higher boiling point. Normally, we cannot determine which intermolecular force dominates, but in this question, we know that since the LDF and the dipole dipole forces contradict each other, the LDF is more dominant. It's a really weird nuance!

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