AQA chemistry unit 4 22nd Jan official discussion thread! Watch

ni_ponies
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#101
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#101
I think i'm pretty sure there are 4 peaks and singlet and triplet
coz CH3 groups are definitely in the same environment, CH2 groups are different and OH so all together 4.
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Couldxbe
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#102
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#102
There are 2 OH, each attached to different carbons...

I think it is a singlet and a triplet, so I got one right
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Preasure
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#103
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#103
Forgot about the rate table until the last minuite, got one but ran out of time. I put van der waals and hydrogen bonding for the im forces, one should at least right. The isomers were good, I usually dont get them but they just felt logical today. Overall it was pretty good, I'm happy with it.
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hanh01
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#104
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#104
(Original post by ni_ponies)
I think i'm pretty sure there are 4 peaks and singlet and triplet
coz CH3 groups are definitely in the same environment, CH2 groups are different and OH so all together 4.
CH3
.......|
CH3-C-CO-CH2-CH2-COOH
.......|
.......OH

but look, counting from the left,
CH3CH3 in the same environment
H from OH
CH2
CH2
OH
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jawads
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#105
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#105
(Original post by Pepe Le Poosh)
it was

.......CH3
.......|
CH3-C-CO-CH2-CH2-COOH
.......|
.......OH

-OHs produces one peak
-CH2s are in the same environment produce another
-CH3s are in the same environment produce another



And i got the same thing for the regeneration question and the fingerprint region.
i think ur right, i put the OHs as two different ones.
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ni_ponies
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#106
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#106
I forgot !!!!! LOL
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Pepe Le Poosh
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#107
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#107
Whats done is done. I'm predicting an A to be 70/90 on this paper. Could be lower because some bits were tricky or just odd. The paper had a weird feel to it. I don't know if anyone agrees with me but that wasn't module 4 'as we know it'.
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jawads
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#108
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#108
for the last question, i knew the answer was fingerprint region, but my mind blanked out 4 like 1min, by then wen i realised it in the examiner had just taken the exam paper.
I was a bit gutted because every mark you lose adds up. I think the timing wasnt great either, we had 8 question, than the usual 7 questions and these questions were fairly long, especially the isomerism ones. Hopefully, they will lower the mark boundary.
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Preasure
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#109
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#109
CH3
.......|
CH3-C-CO-CH2-CH2-COOH
.......|
.......OH

CH3's are one peak, CH2's are two, OH's are two more as they've got different stuff attached to the O-C-.
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Maestor
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#110
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#110
hmmm this splitting is making me insane!
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blahbloo
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#111
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#111
Haha, I think we need to get over it and get the damn papers back quickly as possible!
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person 34
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#112
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#112
I think today it was one of those papers where you think it's easy and then actually it has a lot of pedantic/weird marks which you don't realise becausey you're so used to the usual structure. If I get a high B, I've realised that I won't need to retake - and from what you've been saying, looks like I've got quite a few of the isomers/n.m.r questions right

And if I do get a high B, that is with two nights revision. LmAo.
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hey1990
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#113
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#113
wat did people get for the last part of the Kc, (3-1.6)/2 = 0.7
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Steve1234
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#114
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#114
lol i'm confused now... is the right answer for the number of peaks 4 or 5 ???
I put 4 .....
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blahbloo
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#115
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#115
Apparently it's 3 now.
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Richie90
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#116
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#116
^^if your talking about the moles of stuff i got 2.1 and then 0.7...

Also im pretty sure it was 3 peaks, as the differences in environments we are talking about are not enought to shift the spectrum up/downfield enough to make it a new peak. If you look

boths CH3's are in the same environemt - 1 peak
both CH2's are in (near enough) the same environment - 1 peak
Both OH's are in (near enough) the same environment - 1 peak
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Couldxbe
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#117
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#117
yeah, I got H2 = 2.1 and the other = 0.7

I am sticking with 5. I just don't see how it can be 4 or 3, whereas I can see where I was wrong when I put quartet and triplet (when it should be singlet and triplet). And near enough isn't quite the same as 'in the same'. E.g. propanoic acid, all Hs are in close proximity to each other (and thus 'near enough' in the same environment) yet there are still 3 peaks in the n.m.r spectrum, atleast according to AQA Past papers....

I think I have probably missed out a question somewhere, something doesn't feel right coming out of this paper...
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Pepe Le Poosh
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#118
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#118
i know i fele as though ive missed out a question as well. lol.
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Richie90
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#119
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#119
5 peaks would assume that all are in different environments (bar the CH3's)...however the C=O is highly electronegative and so anything else bonded to it will not matter too much, so its fair to say theat both OH's are in the same environment. same argument for the CH2's..both have a C=O next to them.

Anyway, its one mark, its not the end of the world.

And sadly, Couldxbe, i strongly agree with you about something not feeling right unless its (for me anyways) after AQA Physics A yesterday and that today, my fairly decent prep has gone to the dogs
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Maestor
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#120
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#120
yea...you dont group things together just because they are close to each other that doesnt make sense atall...from what i was taught last year you group them when they are next to the same groups...it worked while i was doing past papers too...so...5! PEAKS!
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