AQA A2 CHEM4 & CHEM5 June 2015 [official discussion thread]

When drawing amino acids, for example adding HCl, do you have to put the cl- in the drawing? For example the june 2014 mark scheme question 6b(i)?

http://filestore.aqa.org.uk/subjects/AQA-CHEM4-W-MS-JUN14.PDF

ok thanks i get it! for the next bit 5ci - what does it mean by the 'integration ratio 3:1"

it is purely the hydrogen environments relative to each other. so a ratio of 3:1 means there are 3 of one environment compared to one of another. don't confuse these with he number of H's though as they are ratios. sorry for late reply

I thought that the integration ratios tell you how many hydrogen's there are in that environment?

They do, that ratio is just cancelled down, if you multiply by 3 you realise it is 9:3 which equals 12 hydrogens, this should make it easier.

Ohhh I see! They're always trying to trick us-.- Thank you both!

Im really struggling with structure determination questions, more specifically the ones that have n.m.r with them Does anyone have any tips? I'm starting to really panic now as I rarely ever get them right and they can be worth alot of marks

Me too! But what someone told me in this thread before is to practice lots of questions. Having done that (and still doing so) I've seen an improvement but still not fully confident. My best advice is to practice, personally I'm trying to master everything else, so if these questions did come up, I know I won't get them all right, so i can afford to drop a few marks

Posted from TSR Mobile

Yeah that's the same position I'm in, I've done all the past papers back to 2002, but I just can't get my head around it Yeah that's a good idea...I'm just praying that not too much of it comes up!

Me too. How are you finding chem5? Generally I prefer chem4 to chem5, but this topic puts me off

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Well I'm a resit student, I had a high B in my chem5 last year, was one mark off an A..was pretty annoyed..But yeah the Chem4 completely let me down, I had a D This is the topic that let me down last year, along with buffer calculations, and just generally last years chem4 paper. I personally thought it was not nice at all. Yeah if chem4 didnt have this topic in it I don't think I'd have much of a problem with it tbh

Guys, help me out with this one.... Why is propanoic acid a weaker acid than ethanoic acid?

Hopefully it'll go well this year (praying proton NMR etc doesn't come up). I didn't find last years chem4 too bad after doing it as a past paper, but it was different, there was no buffer calculation as such and the 7 mechanism was weird. So you not resitting chem5?

Posted from TSR Mobile

propanoic acid is a longer chain, it has more alkyl groups which are electron feeding, this means that the O-H bond is made stronger, than ethanoic acid which has a shorter chain.

propanoic acid is a longer chain, it has more alkyl groups which are electron feeding, this means that the O-H bond is made stronger, than ethanoic acid which has a shorter chain.