Aqa chem 4/ chem 5 june 2016 thread

I guess:

120 UMS = 90/100
108 UMS (A*) = 82/100
A = 74/100

I got CHEM2, PHYA1 exactly right last year and PHYA2 1 mark off, so you can have confidence that I tend to guess quite well!

MADE A FB PAGE, EVERYONE JOIN IT SHARE IT TELL EVERYONE ABOUT IT ITS CALLED

AQA CHEM4 2016 COMPLAINTS

Join share and post all the reasons why AQA need to reevaluate this exam and what they should do about it, include hard questions question style, anything

was there any question we had to say excess NH3? - can't remember where I put it.. I really hope i didn't put it after KCN in ethanolic solution as the next step was OBVIOUSLY H2/Ni (which I hope I put) and which I have gotten correct every time it has come up in past paper questions.. Mind goes loop-de-loop in exams ffs.

what do you think for the other grades.

you know the polypeptide q with the zig zag thing? how did u guys do that? did u leave trailing bonds as a repeating unit or draw a dipeptide?

you know the polypeptide q with the zig zag thing? how did u guys do that? did u leave trailing bonds as a repeating unit or draw a dipeptide?

Guys I said the acyl chloride will give a white precipitate with agno3 but the other one will form a white pp really slowly, is this wrong???

Is this actually going ahead? I understand this might not change anything but I agree they need to know, we did not deserve that.

Pretty decent paper, so close to full marks I think! <3

YES FOLLOW THIS LINK
https://www.facebook.com/groups/148389988911787

Please spread to your FB friends and everyone in your class in school

YES FOLLOW THIS LINK
https://www.facebook.com/groups/148389988911787

Please spread to your FB friends and everyone in your class in school

you know the polypeptide q with the zig zag thing? how did u guys do that? did u leave trailing bonds as a repeating unit or draw a dipeptide?

Did anyone get 0.833 for that
[salt]/[ethanoic acid]
PLEASE :-( im pretty sure it was that? Can anyone remember the numbers and stuff?

trailing as it asked for a section of it

18:30- Updated- Version 2

18:12 Attempting version 1 of the unoffical mark scheme, will keep quoting this for others to see, may even start a thread. Please contribute i will update frequently before i start studying for my bio exam day after tomorrow heh rip

Misc: tell me where these go!!!

Equation representing ethanoic acid as a base with nitric acid:
CH3COOH + HNO3 -> CH3CO+NO3- + H2O

Identify what reagents are needed to distinguish between the two chlorine molecules, incl. observation. (Acyl chloride vs haloalkane (?))
Reagent: water/AgNO3 (?)/named carbonate
Observation: HCl fumes/White ppt./Effervescence -for the acyl chloride.

Which Nitrogen acts as a stronger base a vs. b (where a is attached to the benzene, and b is a tertiary amine) and why?
Nitrogen b due to the positive inductive effect of the carbons on the nitrogen, therefore making the lone pairs more available. Consequently nitrogen a is joined to a benzene so the lone pair delocalises into the benzene ring.

Order of reactions:
D 1
E 2

What is a racemic mixture?
Mixture containing equal quantities of each enantiomer.

How to distinguish between the two:
Expose to plane polarised light, rotates in opposite directions

Chiral Carbon relationship:
They are both mirror images of each other/enantiomers.

4.
Electrophile structure: CH3C(+)O

Reaction mechanism:
Arrow from benzene ring to C+ in CH3C(+)O, then arrow from hydrogen attached to the same carbon as the CH3CO back into the incomplete benzene ring (from carbon 1-4 i believe).

5. Can't remember exact questions, let me know i'll update ! =)
Notes:
Zwitterions have R-N(+)H3 and a COO-
Hydrogen bond between two amino acids: presumably show any partial bond from one hydrogen on one amino acid to either the nitrogen or oxygen on the other.
Dipeptides- essentially amides formed from 2 amino acids.

Advantage of using the polyester suture rather than the polyalkene?
the ester bond in polyester can hydrolyse whereas polyalkene C-C, C-H bonds are too strong thus cannot. Therefore the former can dissolve naturally whereas the former would require manual removal.

7. Conc. Of propanone increases by 100, What is the new rate equation and explain pls:
rate = k[H+]Due to the large excess of propanone, it is no longer affecting the rate as only the H+ concentration limits the speed at which the reaction proceeds.

Why is the initial rate of the reaction used to determine the order of the reactants rather than at any other point during the reaction? Or something
Initial rate takes into account the initial concentration of the reactants which is more accurate since, as the reaction proceeds the concentrations of the different species change. (?)

How do you calculate the initial rate of the reaction from a graph of concentration against time?
Calculate the gradient of the tangent to the slope. (?)

8. Organic synthesis to produce the branched primary amine:
Structure: Same as previous however Br is substituted with CN
Step 3: KCN w/ ethanol (?)
Step 4: H2/Ni, LiAlH4

Question 9 Notes (I don't even need to say the question, everyone knows this question by the number... eek)
Potassium dichromate turns green, either a primary or secondary alcohol, or aldehyde
O-H absorption in the Mass spec
O-H in NMR spectrum, singlet obvs
CH3-O present in NMR spectrum, singlet
RCH2 in NMR spectrum, triplet ?
R(CH3)2 in NMR spectrum, doublet ? uh pls halp don't remember values

Did anyone get 0.833 for that
[salt]/[ethanoic acid]
PLEASE :-( im pretty sure it was that? Can anyone remember the numbers and stuff?