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

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Melody Haratian 2J
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Postby Melody Haratian 2J » Sat Nov 28, 2020 5:10 pm

Can someone explain why CH2Cl2 is a polar molecule based on its molecular shape?

Julianna Shimabukuro 1D
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Re: CH2Cl2

Postby Julianna Shimabukuro 1D » Sat Nov 28, 2020 5:13 pm

It is polar since it is not symmetrical. It would be nonpolar if it was symmetrical and did not have lone pairs on the central atom, but since it has H2 and Cl2, it is not symmetrical.

Ven Chavez 2K
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Re: CH2Cl2

Postby Ven Chavez 2K » Sat Nov 28, 2020 5:23 pm

The bonds between C-Cl are polar while the C-H bonds are nonpolar because the difference in electronegativities is 0.3 for C-H and 0.61 for C-Cl. Based on the idea that the En difference greater than or equal to 0.5 is polar, the C-Cl bonds will affect the molecular shape. Hope this explanation gives some insight into the image I linked with the post.
IoBme.png (5.63 KiB) Viewed 51 times

Olivia Monroy 1A
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Re: CH2Cl2

Postby Olivia Monroy 1A » Sat Nov 28, 2020 5:31 pm

When drawing the lewis structure it might look like the dipole moments could cancel each other out if you drew it with the Cl on opposite sides, but the shape of the molecule is tetrahedral meaning the bond angles are not 90 degrees but are about 109.5, so CH2Cl2 is polar because the C-Cl bond has ionic character/a dipole moment, and the two do not cancel out leaving it polar. Looking at the shape helps to visualize.

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Re: CH2Cl2

Postby Dylan_Nguyen_2C » Sat Nov 28, 2020 8:10 pm

A molecule like CH2Cl2 has dipole moments occurring at the bonds formed by C and Cl due to the difference in electronegativity. You have consider that because the molecule has four regions of electron density, its shape will be tetrahedral. In a tetrahedral molecule, the bond angles are 109.5, meaning that the dipole vectors formed by C and Cl cannot be canceled due to opposing directions. Hope this helps

Christine Ma 3L
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Re: CH2Cl2

Postby Christine Ma 3L » Sat Nov 28, 2020 11:12 pm

CH2Cl2 would be a nonpolar molecule if the 2 C-H bonds and 2 C-Cl bonds were directly across from each other. But since CH2Cl2 is a tetrahedral molecule (4 e- regions), none of the bonds are directly across from each other so none of them cancel, resulting in a polar molecule. Hope this helps!

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Re: CH2Cl2

Postby 805593945 » Sat Nov 28, 2020 11:15 pm

Since C-Cl bond is polar, and the dipole moments do not cancel out, it is a polar molecule.

Ximeng Guo 2K
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Re: CH2Cl2

Postby Ximeng Guo 2K » Sun Nov 29, 2020 8:22 am

Consider the shape tetrahedral: there will be no arrangement for the two C-Cl polar bonds to cancel each other out. Therefore it's polar.

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