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

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Original post by Reg1234567890
Anyone remember whether the other factor for isomerism was based on just Cis isomerism or both cis-trans?


I believe it was both. Something to do with the fact that both carbons holding the bond have a group attached?
Original post by Reg1234567890
Anyone remember whether the other factor for isomerism was based on just Cis isomerism or both cis-trans?


You can't have cis isomerism without trans isomerism? They come as a pair, they're not mutually exclusive.


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Original post by AsheColdwater
I believe it was both. Something to do with the fact that both carbons holding the bond have a group attached?


It's to do with the fact that each carbon atom on either side of the C=C double bond is bonded to 2 different groups.


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Original post by GetOverHere
It's to do with the fact that each carbon atom on either side of the C=C double bond is bonded to 2 different groups.


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where one of them are the same on both carbons (H)
Original post by HediIsLord
where one of them are the same on both carbons (H)


I was about to disagree, then saw we were talking about cis-trans rather than E/Z, where it doesn't have to have 1 group that's the same on both C atoms. You don't have to specify that though, saying 2 different groups on either side is sufficient.
[QUOTE=GetOverHere;65815161]I was about to disagree, then saw we were talking about cis-trans rather than E/Z, where it doesn't have to have 1 group that's the same on both C atoms. You don't have to specify that though, saying 2 different groups on either side is sufficient.

Think I gave answer for why cis, would I get mark for saying that two of the same atom/groups of atoms are bonded to each C of c=c are on same side of c=c
Original post by Reg1234567890
Think I gave answer for why cis, would I get mark for saying that two of the same atom/groups of atoms are bonded to each C of c=c are on same side of c=c


I don't think so, sounds a bit contradictory IMO.
Hey Guys,
Has anyone been given the OCR Sample not the one linked below but the one that OCR send to teachers as an example?
thanks
http://www.ocr.org.uk/Images/171751-...-materials.
Would hextet instead of sextet or multiplet be awarded the mark?
Original post by GetOverHere
I don't think so, sounds a bit contradictory IMO.

Your opinion for marks for an A?
Original post by GetOverHere
I was about to disagree, then saw we were talking about cis-trans rather than E/Z, where it doesn't have to have 1 group that's the same on both C atoms. You don't have to specify that though, saying 2 different groups on either side is sufficient.


said both to be safe
assumed it would be necessary given the emphasis on cis rather than e/z
I did all of my diagrams (displayed formulae and mechanisms) in pencil but ALL of my writing in black pen. That's okay right?


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[QUOTE=HediIsLord;65817089]said both to be safe
assumed it would be necessary given the emphasis on cis rather than e/z

This is what I mean emphasis on cis I can't remember it asking about trans
Original post by nae_xo
I did all of my diagrams (displayed formulae and mechanisms) in pencil but ALL of my writing in black pen. That's okay right?


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should be fine, does say diagrams can be done in pencil

I usually do pencil then pen once I'm sure it's right, rub out the pencil after
Original post by Reg1234567890
This is what I mean emphasis on cis I can't remember it asking about trans


I think it did say cis-trans
Original post by Reg1234567890
This is what I mean emphasis on cis I can't remember it asking about trans


But how can you have cis without trans xD


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Original post by jamesgates1
Peptide has been allowed in every mark scheme.


Phew! ty ty
I believe the answer to the first question of the F324 paper may be the first acid (stearic?)
This was the only option which was clearly saturated. And as the textbook states on page 34 "saturated fats have been known for many years to increase the risk of heart disease by raising blood cholesterol levels."
However technically if either of the other acids were trans fats then they would also be a risk factor so perhaps (optimistically) with the correct reasoning any answer could be feasible? Countering that I seem to remember the wording of the question being chose the option most likely.

Given the style of this question, the PLA stitches and others I would be surprised if the grade boundaries are dramatically high as these have caught many out, me included.
Moving on to F325 now. What do you guys struggle with? I hate some of the buffer questions they thrown in sometimes.
Original post by rory58824
Moving on to F325 now. What do you guys struggle with? I hate some of the buffer questions they thrown in sometimes.


I don't mind the buffer stuff, I find the fuel cell stuff difficult though. I still don't know what to put when they ask for an important difference between a fuel cell and a conventional battery.

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