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AQA A-level Chemistry paper 2 7405/2 Unofficial Markscheme Watch

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    U mans know the drill by now, if ur answersmatch, thumbs up the post ygm:

    - 9.07g (first question mass thing)
    - 0.04 (t=0 tangent initial rate)
    - 0.65
    - 0.0281 mol^-1 dm^3 s^-1 (rate constant, k)
    - 50.7 kjmol^-1 (the activation energy)
    - 0.62 (rearrange kc and work out moles of suttin)
    - 1.45x10^-4 (took an L on this question, correct answer is 145mg)
    - 3 peaks in carbon 13 nmr
    - 2 peaks in proton nmr
    - There was a nucleophilic addition-elimination reaction somewhere and the product was N-ethylpropanamide

    - the final 2 questions, basically for the first one, you gotta talk about inductive effect and benzene ring causing lone pair of electron on n of the ammonia, to become partially delocalised onto the ring, making it less available, the one where the ammonia was furthest away from the benzene ring with an alkyl group before it (ch2ch2) was the strognest, due to positive inductive effect. the weakest base was the one where the ch2ch2 was at the end, and ammonia was inbetween the benzene ring and the alkyl group, due to negative inductive effect, and lone pair ultimately fully delocalising onto the ring), the middle one was just the ammonia attached to the ring.
    (I think it was FEG or suttin)

    - for the final one though, for the intermediate you should get a chloro or bromo group attached to the ch2, and it is ultraviolet light + cl2 or br2
    then for the second intermediate, you should have the cl or br replaced by a CN, and reagent = kcn, conditions is aqueous & ethanol as solvent)

    then the final stage (dont know if u had to talk about it), but basically heat the second intermediate under reflux with conc hcl/sn, to form the final product.

    ayt safe
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    That paper was a blessing!
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    (Original post by brumtown0121)
    U mans know the drill by now, if ur answersmatch, thumbs up the post ygm:

    - 9.07g (first question mass thing)
    - 0.04 (t=0 tangent initial rate)
    - 0.65
    - 0.0281
    - 50.7 kjmol^-1 (the activation energy)
    - 0.62
    - 1.45x10^-4 (i know my answers wrong so holla the right one)
    - 3 peaks in carbon 13 nmr
    - 2 peaks in proton nmr
    - the final 2 questions, basically for the first one, you gotta talk about inductive effect and benzene ring causing lone pair of electron on n of the ammonia, to become partially delocalised onto the ring, making it less available, the one where the ammonia was furthest away from the benzene ring with an alkyl group before it (ch2ch2) was the strognest, due to positive inductive effect. the weakest base was the one where the ch2ch2 was at the end, and ammonia was inbetween the benzene ring and the alkyl group, due to negative inductive effect, and lone pair ultimately fully delocalising onto the ring), the middle one was just the ammonia attached to the ring.
    (I think it was FEG or suttin)

    - for the final one though, for the intermediate you should get a chloro or bromo group attached to the ch2, and it is ultraviolet light + cl2 or br2
    then for the second intermediate, you should have the cl or br replaced by a CN, and reagent = kcn, conditions is aqueous & ethanol as solvent)

    then the final stage (dont know if u had to talk about it), but basically heat the second intermediate under reflux with conc hcl/sn, to form the final product.

    ayt safe
    Thanks for this!! I don't think hcl/sn is right though because that's only for reducing no2 on benzene ring. Should be h2/nickel or LiAlh4
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    There was no question on the back page right?
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    Jeeez, I messed up that last question man. 145mg for that other one. I got 15.8 or suttin like that for Ea.
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    i got 0.074 for tangent but its dependent on the line u draw got like 0.38/ 5.0
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    (Original post by brumtown0121)
    U mans know the drill by now, if ur answersmatch, thumbs up the post ygm:

    - 9.07g (first question mass thing)
    - 0.04 (t=0 tangent initial rate)
    - 0.65
    - 0.0281
    - 50.7 kjmol^-1 (the activation energy)
    - 0.62
    - 1.45x10^-4 (i know my answers wrong so holla the right one)
    - 3 peaks in carbon 13 nmr
    - 2 peaks in proton nmr
    - the final 2 questions, basically for the first one, you gotta talk about inductive effect and benzene ring causing lone pair of electron on n of the ammonia, to become partially delocalised onto the ring, making it less available, the one where the ammonia was furthest away from the benzene ring with an alkyl group before it (ch2ch2) was the strognest, due to positive inductive effect. the weakest base was the one where the ch2ch2 was at the end, and ammonia was inbetween the benzene ring and the alkyl group, due to negative inductive effect, and lone pair ultimately fully delocalising onto the ring), the middle one was just the ammonia attached to the ring.
    (I think it was FEG or suttin)

    - for the final one though, for the intermediate you should get a chloro or bromo group attached to the ch2, and it is ultraviolet light + cl2 or br2
    then for the second intermediate, you should have the cl or br replaced by a CN, and reagent = kcn, conditions is aqueous & ethanol as solvent)

    then the final stage (dont know if u had to talk about it), but basically heat the second intermediate under reflux with conc hcl/sn, to form the final product.

    ayt safe
    The last step in the final qs is wrong, because that step is to convert nitrobenze to phenylamine. You should have instead react it with Ni and H2 gas or LiAlH3 in dry ether.
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    Used H2/Ni catalyst for the last one.

    Anyone else get this?



    6 carbons, 4 13C peaks and peaks at C=O and acid O-H.
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    I got EGF for the benzene ring bit
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    (Original post by brumtown0121)
    U mans know the drill by now, if ur answersmatch, thumbs up the post ygm:

    - 9.07g (first question mass thing)
    - 0.04 (t=0 tangent initial rate)
    - 0.65
    - 0.0281 mol^-1 dm^3 s^-1 (rate constant, k)
    - 50.7 kjmol^-1 (the activation energy)
    - 0.62
    - 1.45x10^-4 (i know my answers wrong so holla the right one)
    - 3 peaks in carbon 13 nmr
    - 2 peaks in proton nmr
    - the final 2 questions, basically for the first one, you gotta talk about inductive effect and benzene ring causing lone pair of electron on n of the ammonia, to become partially delocalised onto the ring, making it less available, the one where the ammonia was furthest away from the benzene ring with an alkyl group before it (ch2ch2) was the strognest, due to positive inductive effect. the weakest base was the one where the ch2ch2 was at the end, and ammonia was inbetween the benzene ring and the alkyl group, due to negative inductive effect, and lone pair ultimately fully delocalising onto the ring), the middle one was just the ammonia attached to the ring.
    (I think it was FEG or suttin)

    - for the final one though, for the intermediate you should get a chloro or bromo group attached to the ch2, and it is ultraviolet light + cl2 or br2
    then for the second intermediate, you should have the cl or br replaced by a CN, and reagent = kcn, conditions is aqueous & ethanol as solvent)

    then the final stage (dont know if u had to talk about it), but basically heat the second intermediate under reflux with conc hcl/sn, to form the final product.

    ayt safe
    I got the same as you for the base ammonia one, I can't tell if everyone has got the same or different tbh looool
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    Number of moles = 0.789 (maybe for the Kc question?)
    rate constant k = 0.028
    H2/Ni Catalyst or LiAlH4
    The methylbenze should be in excess (in order for 1 substitution only)
    I got EGF (not sure)
    To distinguish between KLMN, add tollen's reagent to get N (only one with silver mirror), NaHCO3 to the remaining KLM to get the one without COOH (L I think, only one WITHOUT effervesence) to KM add K2Cr2O7/c.H2SO4 to identify K (only one with orange to green) and therefore M (by elimination)
    145 mg for P (I think)

    Correct me if I'm wrong
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    Did anyone get 870Mg for one of the questions? The Ideal Gas Equation?
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    (Original post by Hassankhan2405)
    Did anyone get 870Mg for one of the questions? The Ideal Gas Equation?
    I think I got 947mg or something but I think I'm wrong :/ hated that paper


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    Grade boundaries?? I think they'll be similar to the old spec, 75% for an A 80% for A*
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    (Original post by Hassankhan2405)
    Did anyone get 870Mg for one of the questions? The Ideal Gas Equation?
    Im pretty sure its 145mg
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    i got 1100mg ....... yh ill just leave
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    (Original post by markschemes)
    Used H2/Ni catalyst for the last one.

    Anyone else get this?



    6 carbons, 4 13C peaks and peaks at C=O and acid O-H.
    dont remeber this- what was it for??? i think i got like C(CH3)3COOH
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    (Original post by eza11)
    dont remeber this- what was it for??? i think i got like C(CH3)3COOH
    Something about draw structure of cyclic compound using Table 1 and Table 3 of the formula booklet.
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    (Original post by markschemes)
    Something about draw structure of cyclic compound using Table 1 and Table 3 of the formula booklet.
    omggg did it say cyclic ffs
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    Does anyone remember how many marks each thing was?
 
 
 
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