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OCR A2 CHEMISTRY F324 and F325- 14th and 22nd June 2016- OFFICIAL THREAD

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Can someone explain a Pi electron please?
I'm slowly beginning to doubt everything i know...
Original post by rahim10
Can someone explain a Pi electron please?
I'm slowly beginning to doubt everything i know...


P orbitals overlap above and below plane of molecule to produce a region of electron density called a pi bond :smile:
Original post by itsConnor_
Remember in making aliphatic amines:
Halogenoalkane + NH3 (hot, in ethanol) --> Amine + HCl

The amine FURTHER REACTS with another halogenoalkane to make the (chain)2NH if that makes sense. Hasn't come up in years

U need excess nh3
Wish it was at 9 instead of 1
Original post by Rust Cohle
For the crammers:

https://goo.gl/nVvgw9


Thanks for that!😊
Do you have anything similar for f325?
Last minute question!

I was wondering if one could use pencil for drawing mechanisms? Where else one can use pencil for? (can it be used for tables,diagrams, graphs?
Original post by KB_97
Wish it was at 9 instead of 1


thought it starts at 2
Original post by s008454
Thanks for that!😊
Do you have anything similar for f325?
F325 resources should be there after exam today. Same link so just refresh for updates
Original post by curious_M
Last minute question!

I was wondering if one could use pencil for drawing mechanisms? Where else one can use pencil for? (can it be used for tables,diagrams, graphs?


i don't recommend using pencil for tables.
image.jpeg

Could anyone explain this? Why is the molecular ion COO instead of COO-?
So phenol can't react with a carbonate but it can react with a Naoh and Na to make sodium phenoxide? But you can't make sodium phenoxide using a carbonate like na2co3?
Original post by lai812matthew
i don't recommend using pencil for tables.


Thanks;How about drawing mechanisms?
Original post by AqsaMx
image.jpeg

Could anyone explain this? Why is the molecular ion COO instead of COO-?

I assume you mean why COO+ rather than COO- minus? That's just how you have to write fragments for mz - always positive.
When forming a polyester, how do you know if you should react a hydroxyacid (both OH and cooh in same monomer) or react two different monomers together? will it say in the question?
Original post by qweening
P orbitals overlap above and below plane of molecule to produce a region of electron density called a pi bond :smile:


Thanks, so pi electron is an electron found at a Pi bond?
You won't see an amino acid with both COOH and NH2 in the R group
Hey guys do we need to know how chiral synthesis works?

Good luck to everyone today!


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Been getting A*s but just hope there's no horrible NMR
I was wondering if one could use pencil for drawing mechanisms?(please)

Thanks
All the best for the exam
Halogenoalkane reacts with excess nh3 making primary amine. The reason you use excess is so that you make mostly primary amine instead of having the primary amine further reacting with the halogenoalkane making a secondary amine because primary amine is a better nucleophile than nh3.

So for example with a halogenoalkane that has cl in it. You make the primary amine and hcl. The hcl can further react with another nh3 making nh4+cl-

Does that make sense?

Original post by RayMasterio
When forming a polyester, how do you know if you should react a hydroxyacid (both OH and cooh in same monomer) or react two different monomers together? will it say in the question?


They would tell you to draw the repeat unit of the polymer using the molecule they give you. Don't add your own random monomer. I hope I understood your question correctly

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