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Aqa as chemistry paper 2 2017 unofficial markscheme

Please reply with any questions you remember so I can put them together

Also, how did you find the exam?
Personally, I found it way difficult than last years paper

Label axis (1 mark)
-energy

Drawing curve for a higher temperature (1 mark)
-shifts to the right and is lower

Why high temp mean faster rate of reaction (2 mark)

Working out Mr using PVnRT (5 mark)
81.5

Complete combustion equation (1 mark)

Working out alkane using combustion data (3 marks)
C13H28

Empirical/molecular formula (4 marks)
Empirical: c3h7
Molecular: c6h14

Stereoisomers & compound (6 marks)

KJ (3 marks)
0.033

Why rinsing was important (1mark)
Ensure all acid-alkali react

What are concordant results (1mark)
Two or more results within 0.1

Number of hydrogens (1 mark)
38

Percentage yield (3 marks)
65.8%

Dehydration with cyclohexanol (4 marks)

Separation of two products (6 marks)
I think one was an aldehyde and one was an alcohol

why Chloroethene has lower bp that PVC

PVC plasticisers (2 marks)

Multiple choice (15 marks)
Bond angle between O & H - 104.5
Formula of Gas B - ?
(edited 6 years ago)

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Reply 1
I thought it was really hard compared to last year- just required lots of thinking differently about things and lots of unit conversions to trip you up
The multiple choice I found super difficult!
Original post by zzgb001
I thought it was really hard compared to last year- just required lots of thinking differently about things and lots of unit conversions to trip you up
The multiple choice I found super difficult!


All the maths questions were difficult too!
Was there a question on defining stereoisomers because I can't remember it but apparently there was?
Reply 4
Original post by Lazybutmotivated
All the maths questions were difficult too!


I know right! It felt like it didn't really make a distinction between C,B,A or whatever- it was ALL hard
Couple easy questions on the maxwell boltzmann stuff
I can barely remember any of it though
Reply 5
Original post by hereiseverything
Was there a question on defining stereoisomers because I can't remember it but apparently there was?


Oh yeah- I think that was the one that was like compound A,B react with bromine water but C doesnt
Deduce their structures
B has stereoisomers what's a stereoisomer etc
I got 28 hydrogens. Also I thought the paper was quite nice
Also percentage yield was 65.8% for me
i'm sorry but I have been getting near full UMS for all my exams so far , but I can hand on heart say I completely flopped this ******** exam.
Reply 9
Original post by chelseafc141
Also percentage yield was 65.8% for me


Same here
Reply 10
Pretty sure mr with pVnrt was 83.3 aswell?
Original post by chelseafc141
Also percentage yield was 65.8% for me


I got this too. I just got mixed up With the numbers, sorry
Original post by Dws171
Pretty sure mr with pVnrt was 83.3 aswell?


It was 81 something
i got 38 hydrogens and i wrote PVCS are insulating because it didnt have delocalised electrons... and i got something like -1259 for a enthalpy question god knows which one.
Reply 14
Hydrogen moved from A to B because this produces a more stable tertiary carbocation

Compound A: pent-1-ene no stereoisomers
Compound B: pent-2-ene stereoisomerism
Compound C: cyclopentane (doesn't decolourise bromine no double bond)

Phosphoric acid: H bonds, dipole dipole and VDWs
Cyclohexanol: H bond, Dipole dipole and VDWs but less H bonding than H3PO4 because it only has 1 hydroxyl group and P acid has 3
Cyclohexane: VDWs only
Cyclohexane only has VDWs so lower BP than other compounds so can be distilled to option pure hexane
I got -33000 or something for the enthalpy one
Reply 16
Original post by chelseafc141
I got -33000 or something for the enthalpy one


Same
1-i got Mr= 81. something
2-q for enthalpy change qn= 290
3-C13H28
4- 562. something for the mass in mg qn
5- concordant = within 0.1cm3
6 - a was geometrical isomer, b was alkene, c was cycloalkane
7 - phosphoric acid is all the intermolecular forces, used distillation
8- several skeletal qns, one was aldehyde, other had a methyl group and the last one was but-2-ene
9 - mcq angle was 104.5
10 - 33.3 for water mcq
thats all i can remember, overall good paper hoping for over 60 to make up for the terrible mark i got in paper 1
Original post by HateOCR
1-i got Mr= 81. something
2-q for enthalpy change qn= 290
3-C13H28
4- 562. something for the mass in mg qn
5- concordant = within 0.1cm3
6 - a was geometrical isomer, b was alkene, c was cycloalkane
7 - phosphoric acid is all the intermolecular forces, used distillation
8- several skeletal qns, one was aldehyde, other had a methyl group and the last one was but-2-ene
9 - mcq angle was 104.5
10 - 33.3 for water mcq
thats all i can remember, overall good paper hoping for over 60 to make up for the terrible mark i got in paper 1

Swear a was the one which didn't have a stereoisomer
Did anyone else get pent-2-ene for A, the one that did have stereoisomers, pent-1-ene for B that didn't have stereoisomers, and cyclopentane for C, not an alkene?

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