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Megan Purl 1E
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Joined: Fri Sep 29, 2017 7:07 am


Postby Megan Purl 1E » Sun Nov 26, 2017 10:10 pm

How do you do question 4.41? It reads:
"Acrylonitrile, CH2CHCN, is used in the synthesis of acrylic fibers (polyacrylonitriles), such as Orlon. Write the Lewis structure of acrylonitrile and describe the hybrid orbitals on each carbon atom. What are the approximate values of the bond angles?"

Andrea Grigsby 1I
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Joined: Fri Sep 29, 2017 7:03 am

Re: 4.41

Postby Andrea Grigsby 1I » Sun Nov 26, 2017 10:21 pm

So first, draw out the Lewis Structure - use valence electrons of each atom to determine the bonding (eg every carbon makes 4 bonds), then once you have the structure drawn out it'll be more straightforward to determine the hybridization - basically the number of electron densities of each carbon, as well as the bond angles because now you have the shape of the molecule.
the Cs in CH2 and CH has sp2 hybridization
the C in CN has sp hybridization
now use the hybridizations to determine the angles
the Cs with sp2 hybridization have 120 angles, because the shape is trigonal planar
while the one with sp hybridization is 180 degrees because essentially the shape is linear

Danah Albaaj 1I
Posts: 50
Joined: Fri Sep 29, 2017 7:07 am

Re: 4.41

Postby Danah Albaaj 1I » Sun Nov 26, 2017 10:24 pm

The two carbons are bonded together. Then you place the 2 hydrogens on of one of the carbons. This is a bent shape. For the other carbon you have a hydrogen by itself and the oxygen bonded to both the nitrogen and carbon. The C-C-N bond will be one diagonal line, and make the shape of that part of the molecule trigonal planar. Then using the areas of electron density you just look at what the hybridized orbitals should be. You should end up with sp^2 for CH2 and CH, the bond angle being 120 degrees. For CN it is sp, with a bond angle of 180 degrees.

I hope this helps!

Justin Lai 1C
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Joined: Fri Sep 29, 2017 7:04 am

Re: 4.41

Postby Justin Lai 1C » Sun Nov 26, 2017 10:46 pm

I think a good way to look at it is also remembering the regions of electron density. Sp2 has three regions of electron density so it is trigonal planar. Sp has two regions of electron density so it is linear

Posts: 44
Joined: Fri Sep 28, 2018 12:15 am

Re: 4.41

Postby 105085381 » Thu Nov 08, 2018 8:03 pm

Does anyone have a good way to remember the degrees per shape?

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