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- เผยแพร่เมื่อ 9 ก.ค. 2024
- Video is a mash up my separate AS and A level mechanism videos and looks at the essentials of the six mechanisms required for A level:
Radical substitution
Electrophilic addition
Nucleophilic substitution (AS and A level)
Electrophilic substitution
Nucleophilic addition
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Dude sounds like he wants to teach defense against the dark arts but is forced to teach potions instead. Thanks for this video by the way, helps me so much in Chemistry A level
Lmao yes
Thank you so much, hoping this one goes well because the first exam was a disaster
@AJ2 between 50-55, so probably a C
A big disaster even the guy with straight As in my class complained
I hope paper 2 saves but I am a little less motivated because of the amount of work I put in revision for paper 1
Jessica Egharevba this is exactly how I feel, the plan was to bang 80% on paper 1 so in case p2 or p3 flops I know I still have a chance for a B but nahhhh OCR loves to see its candidates in tears innit kmt
whatd u get
Thank you so much I really appreciate the time it takes for you to make each of your videos they're so helpful.
Very kind of you to say, thanks. Glad they help
Thank you so much for this - I honestly did not understand this at all and have internal chem exams to go onto second year next week :/ this has genuinely made me understand the subject
Very best of luck with your exams, sure you'll smash them!!!
father of chemistry
thank you so much this was extremely helpful!
Thank you so much. Really hope Tuesday goes well
Do you usually do exam paper walkthroughs? I would appreciate it if you did, I know it must take quite a while so I understand if you can't.
Paper 1 OCR 2019 was a disaster I need to pick marks from paper 2
This was super useful and concise, thank you sir.
Glad it was helpful!
Thank you so much MaChemGuy!
Lovely!
Amazing video!!
Thanks for that - it's a but rough round the edges (sorry)
This guy is a legend
That's very kind of you to say! Thanks :)
very helpful thank you! :)
Thanks, this video super helpful for last minute revision.
👌
This is great!! Could you please make that list of the paper 1 stuff you think will be on paper 3? Thanks so much for your help, sir
Thank you so much
thank you sir !! exam in on tuesday for me hoping it goes well :))
This was really helpful, could you also make a video on how to find the right number of chiral centres in a molecule please? Always confuses me when its asked as a multiple choice question as I can never work it out! Thank you
Thankyou !! Got a level paper 2 today.
Legend
Weird question but should we draw mechanisms/structures in pen or pencil? If pencil would we be penalised?
Rylark Not an examiner but you are allowed to draw diagrams in pencil so doubt it matters what you use
in free radical substitution, is it possible to get a hydrogen radical? or is that chemically not possible here?
Hamzah Nazir Never seen it before
A hydrogen radical is a hydrogen atom
Could you add the conditions required for each mechanism?
So during nucleophilic addition , it’s ok to use either H2O or H+ as the intermediate, or are there specific reactions where you have to specify .
Thx for ur videos :)
U can use either but i think ur less likely to make a mistake if u just use h+ as u dont have to show a dipole
Thx
Says in spec for carbonyls with NaBH4 use H2O for protonation and for haloalkanes with HCN use either H2O or H+
MaChemGuy
Thx
MaChemGuy my teacher let me down then he said you could just use h+ lol 😂
Thank youuu
You're very welcome
Will paper 1 and 2 not ask for the methods of practicals or to draw graphs as this is in paper 3? Is there any other types of questions which is exclusive to a certain paper or more likely to be on/ not on a paper? this is for AQA. Please answer if you can bc i have exams next week.
I teach ocr so can’t say
@@MaChemGuy :( ok nws. Thanks for ur time anyways!
cheers mate
Hiya, please may you do a quick revision video on addition substitution mechanisms for acyl chlorides? I get that they aren't on our spec but I reckon it could be a suggest on a paper 3? But a massive thank you for all the other videos - they're great! :)
Dave If I get time. Thanks, glad they’re helpful
do electrophilic subs. reactions always need a catalyst?
No. Phenols react via ES without catalysts
is it possible to form 1-3-5-tribromobenzene when do bromination of a benzene molecule? btw thank you so much for this video it really has saved me
Hamzah Nazir I think you can only get 2,4,6 substituted but that has to be with phenol or phenylamine and the reagent being Br2. If reagent was Br2 & AlBr3 and you react it with benzene you’ll only get one substitution of the bromine
@@Mstar200 yeah that makes so much more sense thank you :)
One thing I struggle on is, how do u distinguish if it electrophilic addition/substitution or nucleophilic addition/substitution, how do u decide and spot it
If it's addition then it's usually a double bond. Substitution means another molecule has to leave to put the new one in (if that makes sense) even if it's just a H+ ion, if there's more than one product (e.g CH3Cl +HCl) Its substitution
Ella Jasmine thank you, good luck tomorrow
👍
Paper 2 in 1 hour let’s see how it goes probably gonna get a C 😭😭😭 need a B
Hey what grade did u get I'm having my mcq tomorrow
@@ZainAli-nk1rq I got a C lol I knew it. I’m resitting so I can get a B which should be fine
@@KamisatoElias hope you get a B man. I’ll be praying for you, so pray for me as well I’m really hoping for As but I hope I don’t fall short, hopefully you won’t fall short either
what exam board is this?
i havent seen this Bromine with benzene.
Mo Ceasar OCR A
@@MaChemGuy Thanks for the reply. I am doing AQA.
Oh im not alone in my ocr b struggles
No elimination?
Annie Moses Not on OCR A
you haven't done elimination (nucleophilic)
Not an OCR A mechanism
For the formation of nitro benzene in the book it says the electrophile is formed like this: 2H2SO4 + HNO3 => HNO2+ + 2HSO4- + H3O+
Should it be that or the 1 H20 and 1 H2SO4??
Ella Jasmine Different books have different reactions. The one I used is acceptable
They accept both hydronium ions or H+ being made, as long as the crucial NO2+ is made and it's all balanced.
@@MaChemGuy Fab, Thank you! I didn't want to waste time learning the wrong one