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polarity of dichloromethane

Posted: Sat Dec 07, 2019 9:46 am
by Cavalli_1H
at the study session last night he said that dichloromethane (CCl2H2) is polar no matter where the Cls are arranged. Can someone explain why this molecule would still be polar?

Re: polarity of dichloromethane

Posted: Sat Dec 07, 2019 9:56 am
by Sanjana Borle 2K
Since the structure of this molecule is tetrahedral, it is not the same that it looks when drawn as a 2 d Lewis structure. Essentially a tetrahedral structure can be rotated in different ways that is not accurately depicted in a 2 d structure, so if the H's and Cl's were opposite each other the molecule would still be polar. Imagine that the atoms on the left and right of the C are actually going into and out of the page, but not at 180 degree angles. Because of the tetrahedral structure it wouldn't cancel.

Re: polarity of dichloromethane

Posted: Sat Dec 07, 2019 12:59 pm
by Cavalli_1H
405310750 wrote:Since the structure of this molecule is tetrahedral, it is not the same that it looks when drawn as a 2 d Lewis structure. Essentially a tetrahedral structure can be rotated in different ways that is not accurately depicted in a 2 d structure, so if the H's and Cl's were opposite each other the molecule would still be polar. Imagine that the atoms on the left and right of the C are actually going into and out of the page, but not at 180 degree angles. Because of the tetrahedral structure it wouldn't cancel.

Does that mean that all tetrahedral molecules are polar?

Re: polarity of dichloromethane

Posted: Sat Dec 07, 2019 1:12 pm
by Sanjana Borle 2K
Unless all four surrounding molecules are the same, all tetrahedral molecules are polar.