Shiv Loves Maths
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Doing A2 AQA chemistry and OCR biology. I've got a ton of advice from my teachers
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C-rated
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I would love to know how to tell which mechanism I need to write down (e.g. nucleophillic addition, electrophillic substitution etc)
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Uberalpha
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(Original post by Shiv Loves Maths)
Doing A2 AQA chemistry and OCR biology. I've got a ton of advice from my teachers
How did you revise for your AS Chem? Also, if you did Biology AS, how'd you revise for that?

If you can, sorry to ask, but can you tell us your AS results?
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flowerspace
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How would you recommend learning all the organic synthesis reactions? I struggle to remember them all ^_^ also the transition metal colours when you add OH- and NH3
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thefatone
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(Original post by Shiv Loves Maths)
Doing A2 AQA chemistry and OCR biology. I've got a ton of advice from my teachers

yes what about physics?

(Original post by C-rated)
I would love to know how to tell which mechanism I need to write down (e.g. nucleophillic addition, electrophillic substitution etc)
1. when you have something with a double bond?
2. when you need to make an alcohol or just add a functional group onto something

it's electrophillic addition and nucleophillic subsitution
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(Original post by thefatone)
1. when you have something with a double bond?
2. when you need to make an alcohol or just add a functional group onto something

it's electrophillic addition and nucleophillic subsitution
oh I mean like the ones on the chem4 paper 2014, I just can't figure out how to tell which mechanism it is. Ironically I can do the actual mechanism near perefectly but drop like 3-4 marks every paper because I can't tell which one it is

Image
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thefatone
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(Original post by C-rated)
oh I mean like the ones on the chem4 paper 2014, I just can't figure out how to tell which mechanism it is. Ironically I can do the actual mechanism near perefectly but drop like 3-4 marks every paper because I can't tell which one it is

Image
Image
looks like substitution since the NO2 is replaced with a NH2
dunno i could be wrong but i've never seen something this complicated before o.o
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(Original post by thefatone)
looks like substitution since the NO2 is replaced with a NH2
dunno i could be wrong but i've never seen something this complicated before o.o
electrophilic substitution is indeed the correct answer, but I wrote down electrophilic addition since I thought the NO2+ would be attracted to the delocalized electrons and the hydrogen doesn't get removed

edit: Image
this is the mark scheme but I just can't get my head around why it's substitution
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flowerspace
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(Original post by C-rated)
electrophilic substitution is indeed the correct answer, but I wrote down electrophilic addition since I thought the NO2+ would be attracted to the delocalized electrons and the hydrogen doesn't get removed

edit: Image
this is the mark scheme but I just can't get my head around why it's substitution
Maybe its because one of the hydrogens is substituted with an NO2?
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(Original post by flowerspace)
Maybe its because one of the hydrogens is substituted with an NO2?
That seems logical, it's pretty darn confusing, I do wish AQA would include a list of rules for each mechanism
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flowerspace
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Yeah I don't really get it, I never know what the circle/lines in the middle mean either, something like a pi bond? :/ and I find it really hard to learn all the different mechanisms and which way the arrows go etc
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Shiv Loves Maths
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(Original post by Uberalpha)
How did you revise for your AS Chem? Also, if you did Biology AS, how'd you revise for that?

If you can, sorry to ask, but can you tell us your AS results?
My AS results weren't the best. I got C overall for both chemistry and biology and B for maths. I got B's in all my science mocks but my damn ISAs brought it down. Luckily I'm retaking my ISAs this year.
For AS chemistry I made a ton of notes, watched Erintoul on youtube (He is the best chemistry teacher!) and did loads of past papers.
For AS biology I did pretty much the same, making notes based off markschemes helpen a ton!
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(Original post by Shiv Loves Maths)
watched Erintoul on youtube (He is the best chemistry teacher!)!
I had never heard of that guy before, but by god is he good! Thank you so telling me about him probably going to bring my laptop into school so I can listen to him on headphones in my free periods
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Koalafications
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(Original post by C-rated)
I would love to know how to tell which mechanism I need to write down (e.g. nucleophillic addition, electrophillic substitution etc)
Hi! I may be too late but I really struggle with mechanisms too so I came up with a daft way to remember it

Basically you just remember HAAN BAE
So halogen, acyl chloride and acid anhydride are nucleophillic in name
And benzene and alkenes are attacked by electrophiles so are electrophillic in name of the mechanism then just write what you did- e.g if something was added it's addition


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batoot
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(Original post by flowerspace)
Posted from TSR MobileYeah I don't really get it, I never know what the circle/lines in the middle mean either, something like a pi bond? :/ and I find it really hard to learn all the different mechanisms and which way the arrows go etc
the circle indicates a benzene ring.

each line = a double bond (which tells you it's a cycloalkene)

(Original post by C-rated)
electrophilic substitution is indeed the correct answer, but I wrote down electrophilic addition since I thought the NO2+ would be attracted to the delocalized electrons and the hydrogen doesn't get removed

edit: this is the mark scheme but I just can't get my head around why it's substitution
it is substitution and not addition because:
substitution involves displacing a functional group.
addition is adding a functional group without displacing any others.

when you add no2 you displace one of the double bonds in chlorobenzene
Spoiler:
Show
i think this is why lol don't quote me
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flowerspace
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(Original post by batoot)
the circle indicates a benzene ring.

each line = a double bond (which tells you it's a cycloalkene)



it is substitution and not addition because:
substitution involves displacing a functional group.
addition is adding a functional group without displacing any others.

when you add no2 you displace one of the double bonds in chlorobenzene
Spoiler:
Show
i think this is why lol don't quote me
Thank you!

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