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Advanced notice paper F332 OCR SALTERS B

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Original post by Rubyturner94
no, if its bent they say within the ranges 104-109. 120 is for planar molecules.

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Thanks
Reply 181
Original post by Whostolemycookie
Another question sorry, but when the shape of a molecule is bent is it aways 104.5 or can it sometimes be 120?


If there's three pairs of electrons on central atom with one of them being a lone pair, then it's bent with 120 degrees. If there's four pairs of electrons on the central atom with two being lone pairs, then it's bent with 104.5 degrees.


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Original post by super121
If there's three pairs of electrons on central atom with one of them being a lone pair, then it's bent with 120 degrees. If there's four pairs of electrons on the central atom with two being lone pairs, then it's bent with 104.5 degrees.


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What if i was O3?
Reply 183
Original post by Whostolemycookie
What if i was O3?


Ozone is bent with 120 degrees.


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Reply 184
Original post by super121
Ozone is bent with 120 degrees.


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How so?

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Reply 185


There are three regions of electron density around the central atom and one of those regions is a lone pair, so you get a bent shape :smile:
Reply 186
Original post by super121
There are three regions of electron density around the central atom and one of those regions is a lone pair, so you get a bent shape :smile:


Ahh okay thanks

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Original post by Rubyturner94
no, if its bent they say within the ranges 104-109. 120 is for planar molecules.

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Nope. Sometimes "extra" electron density can cancel out can cancel out extra repulsion from a lone pair. Sulfur dioxide, for example, has a bond angle of 120 degrees and is bent. :yep:
Reply 188
Hey guys,

Was just wondering if anyone knew why NO and NO2 display diurnal cycles? :smile:
Reply 189
Original post by etuhse
Anyone know how NO2 can be a radical and not a radical as it is involved in one of the initiation reactions as well as propagation...?


http://wiki.chemprime.chemeddl.org/images/e/ec/NO2_Pic.png
Reply 190
How do nitrogen oxides cause smog production and destruction?

Thanks
Reply 191
Also how is ammonia lost by OH radicals?
Reply 192
why do nitrogen oxides show strong diurnal cycle?
After long contemplation, I've come to the carefully judged conclusion that I am well and truly screwed for this pre-release...
Reply 194
Original post by King Hotpie
After long contemplation, I've come to the carefully judged conclusion that I am well and truly screwed for this pre-release...


Yeah it's too hard to prepare for it and we do not know what the mark scheme wants from us in the pre release question.
Original post by usycool1
Nope. Sometimes "extra" electron density can cancel out can cancel out extra repulsion from a lone pair. Sulfur dioxide, for example, has a bond angle of 120 degrees and is bent. :yep:


At times like this i don't understand chemistry at all... :sigh:
Original post by cheetahs56
At times like this i don't understand chemistry at all... :sigh:


Don't worry, it's not on the spec :tongue:
Original post by usycool1
Don't worry, it's not on the spec :tongue:


Haha true:smile: How are you feeling for this exam?:wink:
Reply 198
Original post by krisshP
why do nitrogen oxides show strong diurnal cycle?


just from reading the pre-release and having a guess i would say that in the morning from rush hour lots of nitrous oxides are released from the combustion of the engine fuel...this then sticks around in the atmosphere so sunlight acts on it and photo dissociates? or maybe just travels to the stratosphere because thats where the high energy uv is. or it might react with ground level ozone (someone clarify?) then at night there are less cars on the road and no sunlight so concentrations decrease....and going on this same principle, in summer the sun is hotter and in winter its not and the general temperature is colder....who knows if this is actually correct :confused:
Reply 199
Original post by krisshP
Also how is ammonia lost by OH radicals?


cant quite figure it out...also this is a journal so its beyond degree level...right?

http://www.ncbi.nlm.nih.gov/pubmed/19031904

EDIT: maybe its nh3 + OH makes NH2 and water? if NH2 can be a radical...and if not then i guess its a termination reaction? thats my only other idea...
(edited 10 years ago)

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