AQA A-level Chemistry Paper 2 12th June 2018 Unofficial Markscheme

What was the question about hydrogen bonds?

N highly electronegative, mor electronegative than H so draws electrodensity away form it so delta - and delta -. C=O also polar. Lone pairs on oxygen attracted to delta + H in N-H

Reply 41

littlediddy

6

Original post by marlodanvers

What were the number of peaks? 4 or 5?

It was a triple as it was next to a CH2

Reply 42

BTAnonymous

22

Original post by Smith_jack99

did anyone get an answer for the c3h4no empirical formula structure question? i went onto extra paper and drew about 40 structures and one of them seemed to work with a nitrile group and an amine group no idea if thats even possible

no. I was like wtf, how do you take away a carbon b****es?

Reply 43

Peeep

6

Original post by marlodanvers

What were the number of peaks? 4 or 5?

4 I’m pretty sure

Reply 44

shawnmendesfan

12

How lenient would they be with Arrhenius? Would they mark it depending on your gradient?

Reply 45

About2GetLaid

6

Original post by Bulletzone

it'll vary a bit but I got 21

LMAO babe it won’t vary THAT much. 21 is definitely wrong. I got 54, that’s the kind of variation that’s acceptable :smile:

Reply 46

Jimmybee123

4

How the hell do you get from C4H6O2 ——-> C3H4NO
Still baffled...🙄

Reply 47

Speersy

5

Original post by Jimmybee123

How the hell do you get from C4H6O2 ——-> C3H4NO
Still baffled...🙄

KCN,its a nitrile im pretty sure

Reply 48

brendonurine

7

Original post by JSC16

It didn’t ask you to find the Kc it asked you to find number of moles of A

Wait wasn’t it the concentration of A we had to find? I got like 0.08 moles and forgot to /0.5, so 0.17 for the concentration seems right

Reply 49

mabelxxx

7

Original post by Jimmybee123

How the hell do you get from C4H6O2 ——-> C3H4NO
Still baffled...🙄

It was empirical formula so was actually C6H8N2O2

Reply 50

BTAnonymous

22

Original post by Jimmybee123

How the hell do you get from C4H6O2 ——-> C3H4NO
Still baffled...🙄

I was so f*ING confused by that. I was thinking, how the hell have these motherf*ckers taken away a carbon?

edit; I know why I couldn't answer that so don't bother correcting me as 3 people already have lol

(edited 5 years ago)

Reply 51

MBK14

9

Original post by Smith_jack99

did anyone get an answer for the c3h4no empirical formula structure question? i went onto extra paper and drew about 40 structures and one of them seemed to work with a nitrile group and an amine group no idea if thats even possible

It was a dihydroxy dinitrile

Ch3 - c (oh)(cn) - c(ch3)h - c(oh)(cn)h

Then twice is twice empirical

(edited 5 years ago)

Reply 52

Peeep

6

What did yall write for the q. Why can a nucleophile attack a halogenoalkane?

- C-Br bond is polar due to the bromine atom being more electronegative.
-c positive Br minus
? I had no clue

Reply 53

j4mil417

8

Original post by Smith_jack99

did anyone get an answer for the c3h4no empirical formula structure question? i went onto extra paper and drew about 40 structures and one of them seemed to work with a nitrile group and an amine group no idea if thats even possible

You had to multiply the empirical formula by 2 and it worked out to be the correct structure once you added HCN to the carbonyl groups

Reply 54

Aaron4president

4

Original post by Bulletzone

carbon 13 nmr had 4 peaks.

-903 for the enthalpy of combustion

I thought it had 5 peaks bc whas it now (CH3CH2)2NCH2CH2CH3??? So the two on the ethyl groups and then the 3 from the CH2CH2CH3 after the nitrogen?

Reply 55

Scootle18

6

Original post by BTAnonymous

no. I was like wtf, how do you take away a carbon b****es?

It was empirical formula. Everything needed to be multiplied by 2, so then it works as a nucleophilic addition mechanism, adding on cyanide ions.

Reply 56

Boomburst

4

Original post by Jimmybee123

How the hell do you get from C4H6O2 ——-> C3H4NO
Still baffled...🙄

C3H4NO is empirical, double it youll get C6H8N2O2 which results from adding 2KCN to C4H6O2, causing the =O to become OH and adding two carbons making 6 total carbons, that's what I got anyway