AQA CHEM4 - 13th June 2012
Chemistry exam discussion - share revision tips in preparation for GCSE, A Level and other chemistry exams and discuss how they went afterwards.
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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(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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Re: AQA CHEM4 - 13th June 2012Topics 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
can someone post every related question to this topic onto here from 2002 and we'll completely dominate these types of questions. -
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Re: AQA CHEM4 - 13th June 2012How are you finding NMR?(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
can someone post every related question to this topic onto here from 2002 and we'll completely dominate these types of questions.
What are you finding hard in the topics you said? I'll try help
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Re: AQA CHEM4 - 13th June 2012you'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.(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
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Yeah I see what you mean, I hate naming it when they hace the N- makes everything complicated(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.
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Re: AQA CHEM4 - 13th June 2012I think of the N as like a number - like 1-methyl etc, I'm not sure if it works.(Original post by Doctor.)
Yeah I see what you mean, I hate naming it when they hace the N- makes everything complicated
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Re: AQA CHEM4 - 13th June 2012Kinda, 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)(Original post by MuffinMonster)
I think of the N as like a number - like 1-methyl etc, I'm not sure if it works. -
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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 shuaib786)
Can someone explain on how to do the proton nmr stuff like working out integration values and integration ratios??? -
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Re: AQA CHEM4 - 13th June 2012So thanks how would you do the 8 c) i) and ii) from the chem 4 jan 2006 paper from the old spec.(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. -
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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.(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. -
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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 xiyangliu)
Unit 5..... So much memorising compare to unit 4 !! Any better ways to revise unit 5 ???
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Re: AQA CHEM4 - 13th June 2012yh plz(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.
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Re: AQA CHEM4 - 13th June 2012how did you get 5? thats the right answer. ii could only get 4(Original post by Mero8)
five I think -
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Re: AQA CHEM4 - 13th June 2012because 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.(Original post by rss.914)
how did you get 5? thats the right answer. ii could only get 4
Last edited by Casshern1456; 31-05-2012 at 21:36.
