Sixth Edition. Question 4.109

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

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Dayna Pham 1I
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Sixth Edition. Question 4.109

Postby Dayna Pham 1I » Thu Nov 22, 2018 4:20 am

Question 4.109 is:
4.109 Estimate the bond angles marked with arcs and lowercase letters in peroxyacetylnitrate, an eye irritant in smog.

It adds an image of the molecule, which is attached.

But why is angle b around 109.5 degrees? It only has two regions of electron density, so I expected it to be linear, with a bond angle of 180 degrees. Is this because it has lone pairs that are not shown in the image, which turns it into tetrahedral arrangement, but bent shape?

Thanks!
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peroxyacetylnitrate.PNG
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Sarah Fatkin 4I
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Re: Sixth Edition. Question 4.109

Postby Sarah Fatkin 4I » Thu Nov 22, 2018 10:27 am

Hi Danya! You're right, it's because oxygen has two lone pairs, which means that the structure has tetrahedral shape and bond angles of 109.5 degrees.

Ava Kjos 1D
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Re: Sixth Edition. Question 4.109

Postby Ava Kjos 1D » Fri Nov 23, 2018 12:40 pm

That is correct, since there are only two single bonds with oxygen you can assume that there are two lone pairs that are not shown to finish the octet around oxygen. Therefore, the shape must be bent with an angle of 109 degrees.

Ian Marquez 2K
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Re: Sixth Edition. Question 4.109

Postby Ian Marquez 2K » Fri Nov 23, 2018 1:25 pm

To reiterate, here there are 4 areas of electron density around the oxygen. The two lone pairs are not shown but have to be present to complete the octet. It is a tetrahedral configuration with the VSEPR equation of AX2E2, meaning that it is of bent shape with about a 109.5 degree angle.

Katelyn Phan 2A
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Re: Sixth Edition. Question 4.109

Postby Katelyn Phan 2A » Sat Nov 24, 2018 10:33 am

Great question! Though not drawn, it is assumed that there are two lone pairs attached to oxygen to complete the octet. Therefore there's a total of 4 regions of electron density. The lone pairs repel each other and the bonded pairs thus creating a bent shape. This has the bond angle of 109.5.


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