CH2Cl2 polarity

(Polar molecules, Non-polar molecules, etc.)

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Rain Taganas 1J
Posts: 22
Joined: Fri Sep 29, 2017 7:05 am

CH2Cl2 polarity

Postby Rain Taganas 1J » Sun Nov 26, 2017 10:51 pm

I understand that polar molecules are non-symmetric and nonpolar molecules are.

On question 25 part a, for CH2Cl2, the Lewis structure shows a symmetric configuration (or nonpolar), but in the solutions manual, it says it is polar. Why is this the case?

Leon Popa
Posts: 18
Joined: Fri Sep 29, 2017 7:04 am

Re: CH2Cl2 polarity

Postby Leon Popa » Sun Nov 26, 2017 11:02 pm

Hi Rain,

When I worked on #25, I thought the same thing. My understanding is that because the lewis structure did not have all H atoms or all Cl atoms, around the central carbon atom, it was not truly symmetrical. Its likely that the bond length between a carbon and a hydrogen is not exactly the same as the bond length between a carbon and a hydrogen. So the lewis structure is not actually symmetrical. So CH2Cl2 is nonpolar. If you were looking at CH4 or CCl4, those would be polar, since the bonds lengths between the central carbon and the surrounding atoms are all the same.

Hope that helps,
- Leon

Elika Asis 3C
Posts: 19
Joined: Fri Sep 29, 2017 7:07 am

Re: CH2Cl2 polarity

Postby Elika Asis 3C » Sun Nov 26, 2017 11:29 pm

Since the carbon atom isn't surrounded solely by hydrogen atoms or chlorine atoms, it isn't considered symmetrical anymore. You should also take into account the distribution of the charges.

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