OCR Chemistry A 2017 Exam Thread (New A Level)

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Oh ok. What about the graph question where I've said as the the temperature increases, the reaction does not become feasible because delta G is >0. So the feasibility decreases no matter the changes in the entropy and enthalpy change? How many marks will I get out of 4?

Depends how it was worded exactly. Did you not mention the intercepts ? Maybe 1/4.if you mentioned the intercepts 3/4 from the info you've provided

Reply 1581

Jitesh

Original post by lewe

Diazonium ions aren't on the spec are they ?

Not anymore
Unlikely they'd ask a question on it tbh but they could.the first step we probably could do ( I think it's nitration of benzene )
Not sure if that is the first step lol

Reply 1582

Jitesh

Original post by Chemndjsshdjdj

With proton nmr, are oh and nh protons always singlets??

And sh etc

Reply 1583

Chemndjsshdjdj

Original post by Jitesh

And sh etc

I thought we only needed to know about oh and nh 😰 Which are the others??

Reply 1584

AJ_P

Original post by Chemndjsshdjdj

I thought we only needed to know about oh and nh 😰 Which are the others??

You're right, only need to know OH and NH

Posted from TSR Mobile

Reply 1585

epsilon9012

I saw a specimen paper and it had 2 chlorobenzenes benzene and from that DDT was formed and then it asked what has to be reacted with the chlorobenzenes to form DDT. What mechanim is this? And how would you figure this out?

Reply 1586

studentsixth

Original post by oni176

I presume that the 4 marks are allocated to:
Delta H being the y intercept
Delta H being negative/the reaction is expthermic
Delta S being negative
And the feasibility changing at the x-intercept

But I reckon that the first two may be combined points so the fourth one could be that the feasibility decreases as the temperature increases?

(edited 6 years ago)

Reply 1587

The_Special_One

Can anyone explain the differences between aliphatic, aromatic and alicyclic?

Are alicyclic molecules aliphatic?

Reply 1588

AJ_P

Original post by The_Special_One

Can anyone explain the differences between aliphatic, aromatic and alicyclic?

Are alicyclic molecules aliphatic?

Aliphatic molecules are straight molecules that may be branched
Alicyclic molecules are molecules with carbon atoms arranged in a cycle/ring
Aromatic molecules are molecules containing a benzene ring. Called that for their strong odour/"aroma"

Therefore alicyclic molecules are not aliphatic. Although one might think aromatic molecules are alicyclic (as benzene is a ring). But that isnt the case, benzene is an exception

anyone correct me if im wrong

(edited 6 years ago)

Reply 1589

sannahx

Original post by Theragingninja

Okay, first identify the topics your dropping marks on and focus on improving them. I usually just use physics and maths tutor for questions by topic.
http://www.physicsandmathstutor.com/chemistry-revision/a-level-ocr-a/module-6/
If you have trouble with any concepts then check out this playlist on YouTube for clarification:
https://www.youtube.com/playlist?list=PLX4e2DxFRGQJLDbDUVVSB97-UwnBX1D6g
If it's difficult to remember the reactions then use a white board or plain piece of paper and try to recall as much as you can from memory, then check what you've missed out and rinse repeat until you've got everything spot on.
Hope this helps and good luck with your exam :smile:

Thank you so much, I will definitely try this! You too :smile:

Reply 1590

sannahx

Original post by LeahAkosua

Have you tried making a poster with all the reaction pathways? On p235 in the OCR Year 2 book, there is a good diagram.

Yes, that helped. Thank you! :smile:

Reply 1591

StA200

Original post by AJ_P

g

Aliphatic molecules are straight molecules that may be branched
Alicyclic molecules are molecules with carbon atoms arranged in a cycle/ring
Aromatic molecules are molecules containing a benzene ring. Called that for their strong odour/"aroma"

Therefore alicyclic molecules are not aliphatic. Although one might think aromatic molecules are alicyclic (as benzene is a ring). But that isnt the case, benzene is an exception

anyone correct me if im wrong

I'm pretty sure aliphatic compounds are alicyclics if they are in a ring (cyclohexane). I think I recall the AS practice paper confirming that in the mark scheme

Reply 1592

ehlamleyla

Original post by StA200

I'm pretty sure aliphatic compounds are alicyclics if they are in a ring (cyclohexane). I think I recall the AS practice paper confirming that in the mark scheme

that is true

Reply 1593

gi9002

how did people find set 1 organic paper, was it just me or extremely easy for a sample paper?

Reply 1594

StA200

Original post by gi9002

how did people find set 1 organic paper, was it just me or extremely easy for a sample paper?

Really nice! The second paper was quite nasty though

Reply 1595

gi9002

Original post by StA200

Really nice! The second paper was quite nasty though

which second paper? the one with 8 marker nmr question at the end?

Reply 1596

StA200

Original post by gi9002

which second paper? the one with 8 marker nmr question at the end?

It had several analysis questions tagged at the end but I personally found them quite tough. Struggled to finish on time too

Reply 1597

epsilon9012

Original post by gi9002

how did people find set 1 organic paper, was it just me or extremely easy for a sample paper?

Can someone please explain q4c from unified chemistry practice paper set 2. I dont understand what mechanism it is and how that is on the specification