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Aqa chem 4/ chem 5 june 2016 thread

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Original post by t0310
What did people put for the test between the haloalkane and the acyl chloride?


Add water
Acyl chloride will give off white misty fumes
Haloalkane will show no change
Original post by SirRaza97
No I don't think so, feelsbadman


You have to add NaOH and nitric acid for the white ppt to form with the haloalkane. The acyl is the one that forms the ppt.
Reply 842
Original post by ethanstoddart
Thought I had it then turns out I made a tertiary alcohol :p:D




SAMEEE. i was actually so happy thinking ive got it
Reply 843
Original post by K2Cr2O7
I put H2O.
haloalkane - no change
Acyl chloride - misty fumes
???? not sure though


I put H20
acyl chloride - steamy fumes (i think its misty fumes passed over ammonia) and turns blue litmus paper red
Reply 844
Original post by K2Cr2O7
I put H2O.
haloalkane - no change
Acyl chloride - misty fumes
???? not sure though


I put that too


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Original post by Luke2shades
I thought maybe a simple tollens test would suffice but wasnt sure because of the Cl. So i did H2O to turn the acy chloride into an alcohol then use K2Cr2O7 turns orange to green


I wrote tollens 😭😭
Reply 846
Original post by thomaarrss
what did everyone out for Ka for a strong acid, i put it fully dissociates so a not needed, didn't know what to put for second mark??


I put that Ka alters depending on the temperaure; an increase in temperature increases Ka. But I kinda guessed...
(edited 7 years ago)
Original post by Ayeros
wasn't the OH a singlet? In this case it would be a triplet. Not sure tho..


The OH was a singlet and it is in what I wrote. OH is always singlet because the proton only connects to an O, which is basically a dead end when talking about splitting. So n=0. So n+1=1. So it's a singlet.
**** that paper

Saddest thing is this is the exam I was feeling confident for.. God knows what unit 5 will be like :frown:
Original post by thomaarrss
what did everyone out for Ka for a strong acid, i put it fully dissociates so a not needed, didn't know what to put for second mark??


I had no idea.

I said Ka is for weak acids only, weak acids partially dissociate so [HA] = [A-] (no idea) and that strong acids completely dissociate so [acid] doesn't remain constant or equilibrium lies far to RHS so [products] very high, [reactants] very low

Original post by t0310
AgNO3 does react with acyl cholrides tho


It does.

It's been in previous markschemes.
Original post by High Stakes
Chemistry teachers looked at it and said it's relatively easy. Should be high grade boundaries.


what are you talking about? teachers get past papers only 24h after exam...
can't it be add AgNO3
steamy fumes for acyl chloride and nothing for the haloalkane?
because haloalkane requires NaOH and HNO3 too in order to show observations
Original post by Ebaysass
Yep White Ppt of Agcl
guys pls what is ethanoic acid + nitric acid, where ethanoic acid acts as a base pls halp
Original post by thomaarrss
i said to make the ester into sodium ethanoate, you had to add water and h+ catalyst to break it up then naoh, then chromatograpy


i said chromatography too mate, couldn't think of anything else apart from filtration and i didn't think that was right
Original post by Ebaysass
Yep White Ppt of Agcl


i think it's supposed to be add water and the white misty fumes of HCl are evolved, both of the compounds had chlorine in, i didn't put that but it's what my friend said
It is KCN with some acid because you need H+ ions. I do not know where people are getting the idea that it is in ethanolic solution.


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Ok so who's gunna make the hitler reacts video? They had the cheek to do it last year so ours better be a whole movie bmt
Original post by the1pedro
Add water
Acyl chloride will give off white misty fumes
Haloalkane will show no change


Bingo.
Original post by Powpao
Did anyone get 1st and 2nd order for the rate equation question. The numbers were so awkward.


I think I might have put that, although it was really just a guess. Most difficult rates question I have ever done :frown:
Original post by Bacardigan
Just thinking about it I think the structure is 4-hydroxy-3,3-dimethyl butanal.


no C double bond O in the IR Spectrum

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