Homework Question 3F.1

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LaurenJuul_1B
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Joined: Fri Sep 28, 2018 12:17 am

Homework Question 3F.1

Postby LaurenJuul_1B » Mon Nov 26, 2018 5:37 pm

Question 3F.1 in 7th Edition asks to identify the types of attractive intermolecular interactions that might arise between molecules of each of the following substances:

a) NH2OH
b) CBr4
c) H2SeO4
d) SO2

I am a bit confused on how to do this. For part a, for example, I can tell that there are hydrogen bonds, but how can you tell that there are also dipole-dipole and London interactions? I thought NH2 was a non polar molecule while OH was a polar one so there would be dipole-induced-dipole interactions. And how could it also have London interactions if both of the molecules are polar? I thought London interactions were just between non polar molecules.

If someone could describe how to determine what interactions there are for each of the substances or in general that would be great.

Thanks!

Andonios Karas 4H
Posts: 30
Joined: Fri Sep 28, 2018 12:27 am

Re: Homework Question 3F.1

Postby Andonios Karas 4H » Mon Nov 26, 2018 5:59 pm

All molecules and atoms can have London forces occur between them due to the rapid fluctuations of electron distribution interacting between two molecules or atoms. It can occur if the molecules are both polar, both nonpolar, or one nonpolar and one polar.

Hydrogen Bonding is always a Dipole-Dipole Interaction; however, a Dipole-Dipole Interaction is not always Hydrogen Bonding.
This is because a hydrogen bond is specifically between a partially negative atom and a H atom with a partially positive charge due to it being bound to the very electronegative atoms N, O, or F.

A Dipole-Dipole Interaction may occur between any partially positive atom from one polar molecule and partially positive atom from another polar moelcule(Not Specifically a H bonded to an N, O, or F)

Therefore, when answering the questions, you know all of them have London forces.

Next you must look at the partial charges on each atom from differences in electronegativity. If a H has a partial positive charge, check if it is bound to a N, O, or F. If it is and there is partial negative charge on another atom, it can form a hydrogen bond and subsequently is a dipole-dipole interaction.

Lastly, if their is an atom with a partial charge and an atom with a partial negative charge (and each molecule is polar), then a dipole-dipole interaction can occur.


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