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

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Original post by tcameron
last years nucleophilic substitution was a normal one though


well i think so, but a lot of people stumbled across the reagent at the second box i remember.
Original post by rory58824
For some reason I have a gut feeling they will ask for mechanisms from the AS course.


last year they did one in nucleophilic substitution. so this year, electrophilic addition it is.
Original post by lai812matthew
maybe they would ask a random question on MRI in medicine


Nope we just need to know of MRI scans as a use for NMR, nothing else.
Original post by itsConnor_
A racemic mixture is a mixture that contains equal amounts of each optical isomer and so, as one rotates plane polarised clockwise and the other anti-clockwise, the rotations cancel each other out

Try this Q https://gyazo.com/8a665c8cf026cc6c9c909a736f7df0c4


Ah ok!

Awesome i see it on page 53! :P Thanks for giving me a heads up!
Reply 1144
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Original post by lai812matthew
definition of high and low density lipoproteins might come up


I don't think actually defining HDL and LDL is in the chemistry spec is it? Just have to know LDL leads to build up of cholesterol and HDL does the opposite I think.
No definition of HDL/LDL in textbook so i assume we don't need to know that!
How's cramming everyone?

http://www.physicsandmathstutor.com/chemistry-revision/ocr-unit-4/
Original post by lai812matthew
last year they did one in nucleophilic substitution. so this year, electrophilic addition it is.


Which Q was nucleophilic sub last year?
Reply 1147
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Original post by lai812matthew
exam board seems to like giving an example of a reaction that is not in the syllabus , and ask you to draw the reagent for a similar reaction. like last years benzene's nucleophilic substitution ,and ozonolysis some years ago lol


ikr, some other year had it too. whats the point of that ur here to test us on our knowkedge or if we can copy what u did


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Original post by Cal 1
I don't think actually defining HDL and LDL is in the chemistry spec is it? Just have to know LDL leads to build up of cholesterol and HDL does the opposite I think.
No definition of HDL/LDL so i assume we don't need to know that!


it's in the book but ofc you don't need to write loads of biological stuffs
Original post by lai812matthew
teacher said there is gonna be an nmr for amides or halogenoalkanes.


Worst nightmare :sad: I guess I should prepare for it anyway
Original post by Cal 1
I don't think actually defining HDL and LDL is in the chemistry spec is it? Just have to know LDL leads to build up of cholesterol and HDL does the opposite I think.
No definition of HDL/LDL in textbook so i assume we don't need to know that!


there are definitions in the textbook, though i haven't seen it mentioned in exam papers as yet
Original post by itsConnor_
Which Q was nucleophilic sub last year?


2b
Reply 1152
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Original post by lai812matthew
it's in the book but ofc you don't need to write loads of biological stuffs


Ahh yes they are! My bad haha
Original post by itsConnor_
From an Edexcel paper: make sure you can do part b) https://gyazo.com/8a665c8cf026cc6c9c909a736f7df0c4

part a) could come up as application of knowledge but they'd prob give some other info


Would part e)i) be nucleophilic addition mechanism? And is part ii) basically that: A molecule with a chiral centre is made. It has two optical isomers, each of which rotate plane polarised light in opposing directions. Therefore the racemix mixture would have no effect on plane polarised light. ?? How do you get three marks out of that?
Original post by itsConnor_
Which Q was nucleophilic sub last year?


That one with fluoride ion and benzene?
Original post by itsConnor_
Which Q was nucleophilic sub last year?


Question 2 b
Original post by bakedbeans247
Yeah and dont forget the Naoh and that its an equilibrium reaction.

But whats racemic? Where is it in the book? o.0 i have never heard of it!


NaOH equilibrium reaction? Is this the making soaps stuff
Original post by KB_97
Would part e)i) be nucleophilic addition mechanism? And is part ii) basically that: A molecule with a chiral centre is made. It has two optical isomers, each of which rotate plane polarised light in opposing directions. Therefore the racemix mixture would have no effect on plane polarised light. ?? How do you get three marks out of that?


in nucleophilic attack, there are two possible position that the OH/ H group is placed.
the chance of it being placed one or the other way round is completely random i.e. 50/50. therefore the ratio of each optical isomer form is 1:1, i.e. a racemic mixture, therefore it will not be optically active, no effect when there is plane polarised light
(edited 7 years ago)
Original post by Serine Soul
Worst nightmare :sad: I guess I should prepare for it anyway


They'll surely tell you the compound is a halogenoalkane then tell you to work out its structure right? There wouldn't be a peak for bromine would there?
Original post by tcameron
NaOH equilibrium reaction? Is this the making soaps stuff


page 35 making biodiesel :smile:

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