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AQA CHEM4 - 13th June 2012

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Original post by Bright.Inspiration.
Did the jan 02 paper and got 77% .. Lost a ton of marks on questions about an N-substituted amide


Is the stuff from 02 still useful for the current spec, I thought there would be a lot of changes.
Original post by Casshern1456
Is the stuff from 02 still useful for the current spec, I thought there would be a lot of changes.


There's only a few marks for questions on stuff we don't study - the majority of it is still relevant :smile:
Original post by Bright.Inspiration.
There's only a few marks for questions on stuff we don't study - the majority of it is still relevant :smile:


You've just increased my workload for CHEM4 by 500%.

:nopity:
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Original post by Bright.Inspiration.
Did the jan 02 paper and got 77% .. Lost a ton of marks on questions about an N-substituted amide

Ergh I hate the N substituted stuff, it's annoying to name because I always forget how :sigh:


Original post by Casshern1456
You've just increased my workload for CHEM4 by 500%.

:nopity:

Just be a little careful when checking the MS - the new specification has changed quite a bit of the answers! (especially for the 'give a reason'/'explain') based questions :h:
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Right just finished NMR, Mass Spec & Infra-red :s-smilie: Didn't do Organic Synthesis. Plan on doing that when I start doing questions :tongue: Didn't find the NMR section too bad oddly, but I think the actual paper questions are MUCH harder :frown:
Original post by Casshern1456
You've just increased my workload for CHEM4 by 500%.

:nopity:



You'll thank me when you get your A* :wink:
Original post by Bright.Inspiration.
You'll thank me when you get your A* :wink:


lool thanks :biggrin: but I have a d in CHEM4 and an a grade *just* in CHEM5 and I'm only resitting CHEM4, no A* for me :L
Is an isomer an enantioner if it has double bond with an oxygen? So really then it only has 3 different compounds attached to it....according to a past paper, it is.....
Original post by masterhr1
Is an isomer an enantioner if it has double bond with an oxygen? So really then it only has 3 different compounds attached to it....according to a past paper, it is.....


I didn't think it was :frown: I thought the carbon had to be bonded to 4 different groups. Could someone clear this up please? :confused: Also which past paper are you looking at so I can check it out? x
^ 4 different groups attached to the C atom is an enantiomer
ok, I read the mark scheme wrong. Sorry for the stress.
Reply 271
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Saraah_x
Has anyone got any good revision sites/ notes/ help!! for NMR spectroscopy and structure determination etc? I struggle with it so much :frown:
Can anyone help me with how to find the rate determining step :-( x
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Original post by nicknickmac
Can anyone help me with how to find the rate determining step :-( x

It's simply the SLOWEST step!

Basically you look at the equations, you'll see (probably) a few Carbocation + Nuclueophile, which will be very fast! Then you'll see one C-Br breaking, which would take ages. That would be the rate determining step :h:
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Original post by Saraah_x
Has anyone got any good revision sites/ notes/ help!! for NMR spectroscopy and structure determination etc? I struggle with it so much :frown:


Ergh, I hate that too :tongue:

I don't really think it's taught well...anywhere tbh. Best I can do is offer you any help, just go through the book and if you get stuck just PM me or post on here and i'll try my best to help :h:
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Original post by Doctor.
Ergh, I hate that too :tongue:

I don't really think it's taught well...anywhere tbh. Best I can do is offer you any help, just go through the book and if you get stuck just PM me or post on here and i'll try my best to help :h:



It's so hard!:confused: Yep deffo agree. Thankyou! I may just have to take you up on that offer :h:
for naming N-substituded amides isn't it just say N-trimethyl-propanoic acid?

that would be a nitrogen attached to three methyl groups, bonded to the C group on the propanoic acid group
so its ch3ch2co-N(Ch3)3

is that wrong? that's just me going on what I know, that the N- part is what is attached to the nitrogen.

if that's not correct then there's a hole in my method of naming :frown:
(edited 11 years ago)
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Original post by callmenighthawk
for naming N-substituded amides isn't it just say N-trimethyl-propanoic acid?

that would be a nitrogen attached to three methyl groups, bonded to the C group on the propanoic acid group
so its ch3ch2co-N(Ch3)3

is that wrong? that's just me going on what I know, that the N- part is what is attached to the nitrogen.

if that's not correct then there's a hole in my method of naming :frown:


I agree with the "-N-Trimethyl" its the bit before that, I disagree with though.

Where are you getting the Propanoic acid from? That part could have been been an Aldehyde?

I would say its Propanamide N-trimthyl

Nice that covers the CH3CH2CON bit and ofcoure the N-(CH3)3 bit is correct?

That's just what I think though :s-smilie:
When an chiral compound is formed at the end of a reaction, how can we tell if it's a racemic mixture that's formed?


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Original post by masterhr1
When an chiral compound is formed at the end of a reaction, how can we tell if it's a racemic mixture that's formed?


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It's always formed as a racemic mixture. Because the species attacking the compound has equal probability of attack from above and below the plane - leading to equal amounts of each enantimer/racemate

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