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

Reply 80

grade boundaries?

OP

Was I the only one who talked about distinguishing K L M N separately???? I gave each letter its own test, cos I swear question said they were in separate test tubes and to my knowledge it wasn't a mixture, it was just separate solutions of each letter, one of u clever clogs lemme know what's up

Reply 82

thelonelyplant

1

What do u guys think A* would be in terms of raw marks?

Reply 83

Balthznar

1

Original post by brumtown0121

Was I the only one who talked about distinguishing K L M N separately???? I gave each letter its own test, cos I swear question said they were in separate test tubes and to my knowledge it wasn't a mixture, it was just separate solutions of each letter, one of u clever clogs lemme know what's up

I think it said how can you distinguish them with the least amount of test tube reactions or something like that.

Reply 84

Hazzab911

Original post by Hassankhan2405

Did anyone get 870Mg for one of the questions? The Ideal Gas Equation?

Yes I did - not sure if its correct though

Reply 85

CaiusMartius

12

Original post by brumtown0121

Was I the only one who talked about distinguishing K L M N separately???? I gave each letter its own test, cos I swear question said they were in separate test tubes and to my knowledge it wasn't a mixture, it was just separate solutions of each letter, one of u clever clogs lemme know what's up

yh I don't remember it saying mixture at any point

Reply 86

10odgerj

1

Original post by Miss.Modesty

I thought the question was asking what the 2 intermediates were and then you write the conditions to get those intermediates and not the final product...

No it said give reagents and conditions for all steps...

Reply 87

newera

2

Original post by brumtown0121

Was I the only one who talked about distinguishing K L M N separately???? I gave each letter its own test, cos I swear question said they were in separate test tubes and to my knowledge it wasn't a mixture, it was just separate solutions of each letter, one of u clever clogs lemme know what's up

yep I put separate reactions!! I thought the question said that we had to use the minimum number of tests or something??

Reply 88

10odgerj

1

Original post by poppyb787

I got about 50000 mg I don't understand how we were supposed to do it without a temperature

We were given a temperature

Reply 89

emilyvrl

Step 1 :
H2SO4 + HNO3 --> H2NO3 + HSO4

Step 2 :
Methylbenzene + HNO3 --> methylnitrobenzene + H2O ( conc H2SO4 catalyst )

Step 3 :
MethylNitrobenzene + 6[H] --> methylphenylamime + 2H2O ( Sn/HCl catalysts , room température )

Okay so that's all I did for the very last question . It makes sense to me but I have no clue if it's right . Any opinions ?

(edited 6 years ago)

Reply 90

Alexhowe99

2

Original post by brumtown0121

Was I the only one who talked about distinguishing K L M N separately???? I gave each letter its own test, cos I swear question said they were in separate test tubes and to my knowledge it wasn't a mixture, it was just separate solutions of each letter, one of u clever clogs lemme know what's up

I bought it asked for tests to identify each functional group in each sample so I treat them as if I was trying to identify them rather than distinguish between samples

Reply 91

brumtown0121

OP

3

Original post by Alexhowe99

I bought it asked for tests to identify each functional group in each sample so I treat them as if I was trying to identify them rather than distinguish between samples

Yhyh I did this too

Reply 92

TheAlchemicalGod

1

We need to start appreciating sarcasm a bit more.......

Reply 93

RKM21

3

Original post by Juicy_J

yeh, there was a six marker on CFCs,

I hate you.....almost got me then! Thank god there wasn't! :s-smilie:

Reply 94

thelonelyplant

1

Anyone wanna play CS go?

Reply 95

biologybuddy

9

it definitely said how could you distinguish between each sample, otherwise it would have just been easy

Reply 96

Sam547

9

Original post by brumtown0121

Was I the only one who talked about distinguishing K L M N separately???? I gave each letter its own test, cos I swear question said they were in separate test tubes and to my knowledge it wasn't a mixture, it was just separate solutions of each letter, one of u clever clogs lemme know what's up

You didn't know which one was in which.
So you could have added NaHCO3 to all of them to see which ones bubbled and hence which ones had carboxilic acids, which was two of them. So now you have two group of two test tubes. I think you then could add acidified potassium dichromate to one and see which one turned green, and then add tollens to the other group and see which one formed a silver mirror to working out which test tube was which. NB there could be other routes to answering this question but this way only two tests were used on each test tube. Hope this helps :smile:

(edited 6 years ago)

Reply 97

anna_sivakova

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 (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

that went so much better than the other paper for me. ... i got the right answer for all of the maths questions so hopefully that should balance my awful last 2 questions ahhaha

Reply 98

username2021515

2

Most of my classmates,me included, got around 130mg give or take depending on rounding.
Here was my method:
Work out volume of gas lost as CO2 by subtracting intial volume from final volume

Use ideal gas equation to determine moles of CO2 present in gas.

Use the fact that the combustion took place in a 6:1 ratio(Can't remember exactly)

Multiple by Mr of the orginal compound.I also carried all sig figs unitl the end
Also would I be marked down for naming it as N-ethylpropanamide as opposed to ethylpropanamide?I know it is techically the exact same thing but as we know AQA pedantry knows no bounds.