AQA A Level Chemistry Paper 2 11th June Unofficial Markscheme

This poll is closed

How many marks do you think you've got?

<4018%

40-5012%

50-6017%

60-7021%

70-8018%

80-9010%

>905%

Total votes: 881

Gnuyheatmik

2019 Unofficial Markscheme for Chemistry Paper 2 11th June

Tell me your answers so I can update this
I can’t really remember much

Equation 1,6-dibromohexane and excess ammonia

C6H12Br2 2 NH3 —-> C6H16N2 2 HBr
or
C6H12Br2 4NH3 —> 2NH2(Ch2)6NH2 2NH4Br (this is probably the correct equation but not sure)

Nucleophilic substitution skeletal formula with ammonia
Cyclic compound by-product
Cyclic compound was from the amino group nucleophilic.sub. on the bromine on the same molecule? reacts with itself.

Equation of ethanoic anhydride (hydrolysis? can't remember)
Forms Ethanoic Acid and Ethanol

Question about a compound and why it has no chiral carbon
No chiral centre because no carbon has 4 distinct groups attached

Explain the term Complementary in terms of DNA strands
Dna strands have complementary base pairs which are able to form hydrogen bonds between them

Draw hydrogen bonds between the strands
3 bonds between C and G
2 bonds between A and T

Circle the components that make up the nucleotide with cytosine
3 Circles around:
Phosphate group, 2-Deoxyribose, Cytosine

Vegetable Fat Question with CxHy

Initial Rates
3.2 x 10^-4
3.2 x 10^-4
First order
Second order

Bunch of numbers I can remember
1.39
182kg
20000
2.57 x 10^9 Arrhenius
28.5% percentage yield
units mol-3 dm9 s-1

Diagram Distillation apparatus
Add condenser and thermometer

Hydrolysing proteins
HCl or NaOH debate about his one

Labelling infrared spectrum F,G,E can’t remember the order
Ester at top (bc no OH peak), then alcohol, then, carboxylic acid.

6 marker on the 2 different compounds (one was a cyclic ketone the other was an alcohol)
-boiling points
Hydrogen bonding in one of them stronger than dipole forces
-Cnmr
-infrared spec

CO2 how does it cause global warming
C=O absorbs IR (heat radiation). Absorbs this energy / retains heat / increases temp of gas (guessing for the second mark).

Minimum number of amino acids in mixture
7

How to see the amino acids
Fluorescent dye and UV/Ninhydrin

How can they tell if the sample has dried by adding anhydrous calcium something ...
Drying cyclohexane makes the solution turn clear ?

The weird question on Z,Z adding the carbons to a skeletal formula
Z,Z, skeletal formula has double bond between 9/10 and 12/23. Z same side, so chain curls

Name mechanism with benzene
Electrophilic substitution

Reaction with bromine finish off the mechanism
- electrophilic addition forming carbo cation then the second bromine ion adds on. Forms dibromo...

Distinguishing between primary and tertiary alcohol
Add acidified potassium dichromate
Orange --> Green
No Change

Last question about nucleophile not being able to attack an Alkene.
I think it’s either:
C=O is polar so the nucleophile can attack the partially positive carbon. The alkene doesn’t have a C=O group so not polar so can’t be attacked by nucleophile.
OR
The nucleophile repels the double bond in the alkene

Insufficient NaH4B added. Test for aldehyde
Add tollens/fehlings
Silver mirror/red ppt

Molecular/Emperical formula question
C5H8 you had to times by 5 to get a whole number
Structure was a branched monomer, e.g H2C=C(CH3)--CH=CH2

Formula of the dicarboxylic acid with an Mr of 118
HOOC- (CH2)2 -COOH

Draw two structures for C6H3Br3
One with One peak in C nmr
One with 4 peaks in C nmr
Benzene ring/kekule structure (several correct answers for this one)
D with 4 peaks on 13C spectrum was 1,2,3-tribromobenzene - C2,C3,C4,C5 symmetrical same as C2,C1,C6,C5

Synthesis question
Nitrobenzene to amine equation finish off equation
Add 6 hydrogens to form 2H2O

Reagents for the reduction of nitrobenzene
Reagents are H2 and Ni (more than one correct answer for this one)

Reagents and conditions for 2 step synthesis to form an amine
KCN aqueous ethanolic
Sn/HCl (think there is more than one correct answer for this one)

Why does stereoisomerism occur
Restricted rotation around C=C bond. Higher priority groups on same or opposite sides of the double bond.

Draw isomers for golf ball
Don't degrade because no polar bonds, so not susceptible to nucleophillc attack.

Isomer of C4H8Br2 with 2 singlet peaks on 1H spectrum
Structure was C(CH2Br)(Br)(CH3)2

How does high-res mass spec differentiate molecules with Mr = 118? - electro spray adds H increasing mass.
Higher precision will distinguish between them because they're the same to the nearest whole number

Why would it be better to use anhydrides rather than acyl chlorides?
Don't use acyl chlorides because toxic HCl fumes/ reacts violently - irritant / acid raid.

IUPAC Names
Buta-1,3-diene
Cyclopentanone
Ethyl Propanoate

(edited 4 years ago)

Scroll to see replies

Reply 1

Edexcel Are mugs

Infra red was I think E G F?

Reply 2

tsunderhi_

I got FGE idk my memory isn't too shabby

Original post by Edexcel Are mugs

Infra red was I think E G F?

Reply 3

Edexcel Are mugs

Yeah I can’t really remember the middle one was g

Original post by tsunderhi_

I got FGE idk my memory isn't too shabby

Reply 4

tsunderhi_

Original post by Edexcel Are mugs

Yeah I can’t really remember the middle one was g

Deffo haha

Reply 5

blueoreo

Any1 got predictions for the gradeboundaries? I got As on the 2017/2018 papers but feel like I'll get a B on these ones. ;c

Reply 6

fdahjatgd

yeah I got FGE but its only a mark

Reply 7

hutcisnon120

The amount of one markers in this paper 🤦*♂️

Original post by fdahjatgd

yeah I got FGE but its only a mark

Reply 8

Maheed

Did anyone acctually attempt the NMR questions? Theyre worth lile 1 or 2 marks each and take loads of time for me

Reply 9

tsunderhi_

I cracked em in the end but yeah it took forever. Was the most i used a pencil during an exam

Original post by Maheed

Did anyone acctually attempt the NMR questions? Theyre worth lile 1 or 2 marks each and take loads of time for me

Reply 10

hutcisnon120

It was too many of these type of one markers that killed the time , Aqa need to start taking into account times conditions when they make these papers kmt

Original post by Maheed

Did anyone acctually attempt the NMR questions? Theyre worth lile 1 or 2 marks each and take loads of time for me

Reply 11

skills0786

Guys, what is the Z,Z Question??? Like I dont recall it...what were the other sub Questions relating to it?? Just so that I can figure out if I actually saw that Q or missed it out... :frown:

Reply 12

username2740239

Original post by tsunderhi_

I got FGE idk my memory isn't too shabby

same here

Reply 13

Oliver.hill1709

You had to convert a nitrobenzene to an aromatic amine for one question I think, Tin (Sn) and HCl

Reply 14

username2740239

Original post by skills0786

Guys, what is the Z,Z Question??? Like I dont recall it...what were the other sub Questions relating to it?? Just so that I can figure out if I actually saw that Q or missed it out... :frown:

It was the one with the really long skeletal formula and you had to finish it off and show the stereoisomerism

(edited 4 years ago)

Reply 15

skills0786

Ooohhh fgs!! I remember seeing that Q, but I dunno if I answered it or not.. Coz I was doing all the Qs in random orders..aah God help me!!! I still dont remember Q's around it tho... :'( Thanks tho!

Original post by 0rg4n1c

It was about hydrolysing vegetable oils with methanol to make esters

Reply 16

Charley T

Polyamides are usually hydrolysed by acids. Ingested proteins are hydrolysed by stomach acid (with the help of enzymes) & stomach acid is HCl.

Reply 17

tsunderhi_

Yeah I tried to remember the Qs around it but I cant. That exam was such a rush :s-smilie:

Original post by skills0786

Ooohhh fgs!! I remember seeing that Q, but I dunno if I answered it or not.. Coz I was doing all the Qs in random orders..aah God help me!!! I still dont remember Q's around it tho... :'( Thanks tho!

Reply 18

username2740239

Original post by skills0786

Ooohhh fgs!! I remember seeing that Q, but I dunno if I answered it or not.. Coz I was doing all the Qs in random orders..aah God help me!!! I still dont remember Q's around it tho... :'( Thanks tho!