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AQA CHEM4 - 13th June 2012

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Topics I'm really scared for is as follows:

rate equations
equilibrium constant
acids, bases and pH calculations
pH curves, titration and indicators
titration calculation
BUFFER BSSSSS

:frown:

can someone post every related question to this topic onto here from 2002 and we'll completely dominate these types of questions.
Reply 281
Original post by Casshern1456
Topics I'm really scared for is as follows:

rate equations
equilibrium constant
acids, bases and pH calculations
pH curves, titration and indicators
titration calculation
BUFFER BSSSSS

:frown:

can someone post every related question to this topic onto here from 2002 and we'll completely dominate these types of questions.


How are you finding NMR?

What are you finding hard in the topics you said? I'll try help :h:
Original post by Doctor.
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:


you're correct, my bad. I would write it N-methyl propanamide though. Propanamide because its essentially an aldehyde with a amine group attached. got it.
Reply 283
Original post by callmenighthawk
you're correct, my bad. I would write it N-methyl propanamide though. Propanamide because its essentially an aldehyde with a amine group attached. got it.


Yeah I see what you mean, I hate naming it when they hace the N- makes everything complicated :sigh:
Original post by Doctor.
Yeah I see what you mean, I hate naming it when they hace the N- makes everything complicated :sigh:


I think of the N as like a number - like 1-methyl etc, I'm not sure if it works.
Original post by MuffinMonster
I think of the N as like a number - like 1-methyl etc, I'm not sure if it works.


Kinda, except the N just basically says what is on the N, rather than saying where it is (because obviously there is only one N in the molecule)
Can someone explain on how to do the proton nmr stuff like working out integration values and integration ratios???
Reply 287
Original post by shuaib786
Can someone explain on how to do the proton nmr stuff like working out integration values and integration ratios???


You'll be given the integration values in the exam so don't worry about that. To get the ratios, just get the lowest common multiple between the numbers and you're done.
Original post by Doctor.
You'll be given the integration values in the exam so don't worry about that. To get the ratios, just get the lowest common multiple between the numbers and you're done.


So thanks how would you do the 8 c) i) and ii) from the chem 4 jan 2006 paper from the old spec.
Unit 5..... So much memorising compare to unit 4 !! Any better ways to revise unit 5 ???


This was posted from The Student Room's iPhone/iPad App
Reply 290
Original post by shuaib786
So thanks how would you do the 8 c) i) and ii) from the chem 4 jan 2006 paper from the old spec.


I'll have a look at it tomorrkw, but be a little wary the old spec did have emphasis on certain topics and less emphasis on others.
Reply 291
Original post by xiyangliu
Unit 5..... So much memorising compare to unit 4 !! Any better ways to revise unit 5 ???


This was posted from The Student Room's iPhone/iPad App


Unit 5 isn't much memorising tbh. It's all about understanding what it going on. So make sure you get exactly what is happening, then question yourself..."but why is it doing that?" - it helps!!!
Original post by Doctor.
I'll have a look at it tomorrkw, but be a little wary the old spec did have emphasis on certain topics and less emphasis on others.


yh plz :colondollar:
Reply 293
Original post by shuaib786
yh plz :colondollar:


Sorry didnt manage to take a look today. Had a ton of other revision to do. Will try take a look tomorrow :colondollar: again sorry!
Reply 294
Untitledc.png

anyone know the answer to the number of peaks
ANYONE HAVE THE JAN 2012 UNIT 4 CHEM PAPER ??!!

pleaseeeeeeeee
Reply 296
Original post by rss.914
Untitledc.png

anyone know the answer to the number of peaks


five I think
Reply 297
Original post by Mero8
five I think


how did you get 5? thats the right answer. ii could only get 4
Original post by rss.914
how did you get 5? thats the right answer. ii could only get 4


because you get 5 groups starting from the most electronegative substance the oxygen, so when you count the protons at every different occurring position along the chain the Hydrogen it is in will affect how many peaks there are. The 2 CH3 group on the second Carbon count as 1 for example.

the 5 groups of proton nmr.png
(edited 11 years ago)
Reply 299
Original post by Casshern1456
because you get 5 groups starting from the most electronegative substance the oxygen, so when you count the protons at every different occurring position along the chain the Hydrogen it is in will affect how many peaks there are. The 2 CH3 group on the second Carbon count as 1 for example.

the 5 groups of proton nmr.png


thanks but why don't the two ch2 groups count as one?

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