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AQA CHEM4 discussion/unofficial mark scheme Watch

  • View Poll Results: How hard did you find this paper?
    Easy, will get an A*
    31
    4.66%
    Moderate
    89
    13.38%
    Harder than any other paper
    405
    60.90%
    I flopped
    140
    21.05%

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    I actually thought I was going to do well in this paper but no screw you AQA
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    (Original post by AngryRedhead)
    They asked for step 3 and 4 I think
    Yeah they will have been step 3 and 4 i just couldn't remember the numbering in the question
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    Could you not write KCN dissolved in ethanol?


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    (Original post by mgill17)
    So I think this was Question 8

    It asked how to basically get an alcohol from an ester
    I basically described Base Hydrolysis...so using NaOH and heating under reflux. Then distilling it off.
    I guess you could've described Acid Hydrolysis too and there's another one some people at my college put but I can't remember that one.

    The structure of S was the same bromoalkane it gave you (was it 2-bromobutane? I can't remember) but you swapped the Br for a Nitrile group

    Step 1
    Reagent was KCN
    Conditions was aqueous

    Step 2
    Reagent was LiAlH4
    Conditions was dissolved in ether

    ---I think that was it someone correct me if I'm wrong------
    it should be ethanol and water mixture to convert haloalkane to nitrile isn`t it?
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    (Original post by DDan123)
    Could you not write KCN dissolved in ethanol?


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    I said KCN in ethanolic conditions, I think they may accept that
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    (Original post by AngryRedhead)
    I missed half of the questions ngl the nmr one right at the back didn't even get one word written on it

    I think I'll definitely need to take this again next year. I'd be surprised if I got anything above a C tbh
    Nah, that NMR one lmao. I knew NMR would haunt me, but that was just... ugh.

    I'm so sad that I'm not sad. - I don't even have time to mourn bc maths tomorrow which I cba for now. ):

    Well, I guess we still have unit 5.
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    (Original post by iselhong)
    it should be ethanol and water mixture to convert haloalkane to nitrile isn`t it?
    Oops yeah. I meant ethanolic that's what I put in the paper. Idk why I put aqueous there..I'll change it!
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    (Original post by Anon_98)
    Nah, that NMR one lmao. I knew NMR would haunt me, but that was just... ugh.

    I'm so sad that I'm not sad. - I don't even have time to mourn bc maths tomorrow which I cba for now. ):

    Well, I guess we still have unit 5.
    The entire paper was horrible and ugh imho

    Best of luck with your maths, I hope it isn't as bad as this paper was.

    You still have Unit 5, I already did it and got a B in it, Unit 5 is easier
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    Such a horrible paper!!! The questions were so difficult and it was far too long! I ran out of time 😥
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    Reaction orders : A-1
    B-2
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    Just so gutted. Not sure if I got an A and the Empa wasn't great either. Think I need like full UMS unit 5 lool


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    (Original post by logicmaryam)
    Heey guys, I think we can all agree this paper was one of the hardest CHEM4 papers ever.
    We'll discuss the answers and compile an unofficial mark scheme. Post your answers here!

    Q1 20 marks
    a) Ethanoic acid in water
    CH3COOH ⇌ CH3COO- + H+ (1)
    b) Ethanoic acid as base with HNO3
    HNO3 + CH3COOH = CH3CHOOH2+ + NO3- (1)
    c) pH of acid? 2.08 (3)
    d) pH when alkali added to acid 2.32 (4)
    e) [salt]/[acid] = 3.33 (3)

    why is chloroethanoic acid stronger than ethanoic acid? (2)
    Chlorine is more electronegative so will withdraw electrons and weaken the O-H bond so H is lost more easily
    I got CH3COOH + H2O ⇌ CH3COO- + H3O+ bc it said reaction with water?
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    (Original post by AngryRedhead)
    The entire paper was horrible and ugh imho

    Best of luck with your maths, I hope it isn't as bad as this paper was.

    You still have Unit 5, I already did it and got a B in it, Unit 5 is easier
    I agree.

    Thank you + I don't think it'll be, no. Or at least I v much hope not bc it's one of the 'easy' resits.

    Oh, nice, I see! Yeah, I also find unit 5 a whole lot better. :'3 Good luck with your next exam too.
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    (Original post by shellypatel2)
    I got CH3COOH + H2O ⇌ CH3COO- + H3O+ bc it said reaction with water?
    I put this too, I'm not sure though

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    (Original post by iselhong)
    Did anyone work out the last question ? i ran out time to finish the explain bit.
    i did something like (HO)CH2CH2C(CH3)2CH2(OH)
    I think it's CH3 O C(CH3)2 CH2CH2 OH
    Anybody else get this?...

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    (Original post by MuslamicJihad)
    The nmr at the end was (I think): CH3OCH2CH2C(CH3)2OH
    This was what I got and it was the most common mistake on the last question. That is a tertiary alcohol and the question clearly said that the compound could be reduced by potassium dichromate which means that it cannot have been a tertiary alcohol.
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    That was officially the worst paper ever and Aqa were very harsh, why did they have to change the syllabus on our year and therefore because we're the final year sitting it they decided to make it memorable. Here's to hopping the grade boundaries are rock bottom.
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    (Original post by RedNebula)
    I think it's CH3 O C(CH3)2 CH2CH2 OH
    Anybody else get this?...

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    Yessss mate same here
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    what did everyone get for Q3f? it was about lidocaine hydrochloride
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    (Original post by logicmaryam)
    Heey guys, I think we can all agree this paper was one of the hardest CHEM4 papers ever.
    We'll discuss the answers and compile an unofficial mark scheme. Post your answers here!

    Q1 20 marks
    a) Ethanoic acid in water
    CH3COOH ⇌ CH3COO- + H+ (1)
    b) Ethanoic acid as base with HNO3
    HNO3 + CH3COOH = CH3CHOOH2+ + NO3- (1)
    c) pH of acid? 2.08 (3)
    d) pH when alkali added to acid 2.32 (4)
    e) [salt]/[acid] = 3.33 (3)

    why is chloroethanoic acid stronger than ethanoic acid? (2)
    Chlorine is more electronegative so will withdraw electrons and weaken the O-H bond so H is lost more easily
    I swear e is wrong, I got 1.2 instead of 3.33
 
 
 
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