The Student Room Group

Aqa chem 4/ chem 5 june 2016 thread

Scroll to see replies

Can we complain because that paper that was a completely different arrangement with questions id never seen before. Next year is the new spec not this year.
Yeah that's what I got
Original post by Suits101
9 I think.
Original post by j.ethers
Ok so for the last question we know it has to be a primary/secondary alcohol because of the dichromate reaction, but the O-H nmr peak was a singlet, suggesting the adjacent carbon to the alcohol group is itself bonded to no hydrogens. Therefore how can it be a primary or secondary alcohol??


exactly!! didn't get it at all, i wrote down that it had to be primary or secondary but then forgot all about it aha! i think we will still get a few marks for our structyre though!
IF this helps anyone - I may be wrong

1.
Equation involved products of CH3COO- and H3O+ (wouldn't be penalised for no reversible reaction sign) (1)

Equation involved products of CH3COOH2+ and NO3- (as above) (1)

pH = 2.something (2 marks)

pH = 2.something

pH = 3.33 (something around this?) (4 marks)

Ka = 9.09 x 10^-3 Units: mol^-1 dm3 (3 marks)

[salt]/[ethanoic acid] = 1.20 (3 - 1 mark for [H+] = 10^-4.48)

Chlorine atom is very electronegative and withdraws electron density from COO- ion (1)
This makes COO- ion less negative and more stable and acidic (1)

Can't remember the last part of Q1

Random answers - may be wrong

9 peaks
Proton b - had alkyl groups, electron releasing, lone pair more available to accept H+ (converse for proton a which had a benzene ring)
Why use PGA: biodegradable so it can be hydrolysed due to polar bonds (C=O/C-O) so sutures will dissolve over time
(edited 7 years ago)
Original post by thomaarrss
did people get like 9% for hydrogen percentage of mass

yes i got 9.4%
Original post by ishabennett
Can we complain because that paper that was a completely different arrangement with questions id never seen before. Next year is the new spec not this year.


this threw me as well
loool that was just so hard, feel like I kept up as well as I could have and the low grade boundaries will keep my grade up
VERY tough exam, a lot of awkward questions that don't typically come up.

I think that may just be the hardest CHEM4 paper I have came across, nevertheless I still think I done well - enough for an A anyways.
I worked so hard for that exam. I hate AQA :frown:
Original post by thomaarrss
did people get like 9% for hydrogen percentage of mass


Yeah can't remember the exact number but definitely around 10%. Because it was something like (23 / 233) x 100.
no one laugh but could it be

(ch3)3-c-o-ch2-ch2-o-h

i came up with that in two mins :frown:((((((((
Original post by jakeysimps11
Same mate, 99% sure its correct


Can't be, it said it reacted to form a green solution with acidified potassium dichromate (VI) so it can't be a tertiary alcohol.
But what I did get was similar: CH3 - O - C (CH3)2 - CH2 CH2 OH
Could R be HOCH2COCH2CH(CH3)2 as it must not be a tertiary alcohol?
(edited 7 years ago)
Original post by chloeabeki
I put k[H+] for the new rate equation, if the concentration of propanal is so high so there's a massive excess, it won't limit the rate I think?

I put the same. I think because its in excess any change will be very small compared with how much there is. Is it like taking [H2O] out of Kw ?
Original post by clarkey500
I think I put 9. I remember counting them and getting 10 which wasn't one of the answers so I gave it a recount! :biggrin:

I got the same
Chemistry teachers looked at it and said it's relatively easy. Should be high grade boundaries.
Well I'm not going to uni after the utter trash that was this years paper.
Thats what i put!
Original post by K2Cr2O7
CH3-O-C(CH3)2-CH2-CH2-OH
Is what i got for the last question.


I got that!!


Posted from TSR Mobile
Welp looks like im resitting next year rip uni dream


Posted from TSR Mobile

Quick Reply

Latest