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Boiling point

Posted: Sun Dec 09, 2018 3:46 am
by Gisela F Ramirez 2H
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?

Re: Boiling point

Posted: Sun Dec 09, 2018 9:24 am
by Emily Kennedy 4L
less distorted electron cloud that is larger

Re: Boiling point

Posted: Sun Dec 09, 2018 5:04 pm
by Rami_Z_AbuQubo_2K
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.

Re: Boiling point

Posted: Sun Dec 09, 2018 5:59 pm
by 305113590
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.

Re: Boiling point

Posted: Sun Dec 09, 2018 6:05 pm
by Nathan Tran 4K
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!