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Edexcel A2 Chemistry Exams -6CH04 (14th June) and 6CH05 (22nd June) Discussion Thread

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Original post by samb1234
Well I nearly always lose at least 3 on mc, and then I just did some stupid stuff on a calculation one I hadn't done one of since I made unit 4 notes like a month ago


Haha same here with the MC xD
Original post by Ayman!
Anyone tried the January 2016 IAL paper? It's super nice, haha.


Yup! :biggrin: But deadly grade boundaries! :tongue:
Original post by samb1234
I have a habit of doing stupid stuff especially in multiple choice (like for example in that paper in my head went well it's clearly not a,b,c so it is d, then when I came to mark it I had crossed C even though I knew the answer) so I prefer papers with lower UMS


I'm the same, I'd rather have a hard paper with low boundaries than an easy paper with high boundaries
https://c838cff4741acb48ae1ed62e59927ff4c2073557.googledrive.com/host/0B1ZiqBksUHNYbVpyRTRJN1lFS00/January%202010%20QP%20-%20Unit%204%20Edexcel%20Chemistry.pdf
for the 17th one, does concentration affect rate in the way that since there are more moelcules, they collide more frequently thus you get the products faster?
Original post by Geethan


Thank you. Does anyone know why phenol is used in the bromine clock reaction?

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n2697
11
Hey guys have two questions;

a)How do you know a solute will dissolve? I know you use the formula ΔS(soln)=ΔH(hydration)-LE but how do you know the rxn is feasible e.g.in entropy calculations you know that the rxn is feasible because ΔS(total) is positive

b)Why is [HA]=[A-] at half equivalence point??

Thanks in advance!
Original post by imnoteinstein
https://c838cff4741acb48ae1ed62e59927ff4c2073557.googledrive.com/host/0B1ZiqBksUHNYbVpyRTRJN1lFS00/January%202010%20QP%20-%20Unit%204%20Edexcel%20Chemistry.pdf
for the 17th one, does concentration affect rate in the way that since there are more moelcules, they collide more frequently thus you get the products faster?


Yes

Original post by TeaAndTextbooks
Thank you. Does anyone know why phenol is used in the bromine clock reaction?

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It's the same principle as to how Sodium Thiosulfate works in the iodine clock reaction.
Why alkenes aren't used may be because of the acidic conditions being able to protonate the alkenes into alkanes?
Original post by n2697
Hey guys have two questions;

a)How do you know a solute will dissolve? I know you use the formula ΔS(soln)=ΔH(hydration)-LE but how do you know the rxn is feasible e.g.in entropy calculations you know that the rxn is feasible because ΔS(total) is positive

b)Why is [HA]=[A-] at half equivalence point??

Thanks in advance!


My thoughts are:

a), if ΔS(soln) is exothermic then ΔS(surr) will be positive, so ΔS(total) will be more likely to be positive overall.

b), at the equivalence point, all of the initial base/acid has been neutralised by the added acid/base, so at the half equivalence point half of the initial base/acid has been neutralised. So [HA] = [A-] .
Original post by Wunderbarr
Yes



It's the same principle as to how Sodium Thiosulfate works in the iodine clock reaction.
Why alkenes aren't used may be because of the acidic conditions being able to protonate the alkenes into alkanes?


Thanks

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thanks for the notes on the first post, they're great :biggrin: how is everyone feeling about unit 4 on tuesday? :smile:
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Aimen.
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Original post by Don Pedro K.
Haha yeah I did decent in it (78/90). you guys probably got high 80s or something but :wink:


I got 78 too :biggrin:
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samb1234
OP
13
Original post by Ayman!
Anyone tried the January 2016 IAL paper? It's super nice, haha.


Oh btw you may have done it already but if you still want spectroscopy practice the last question of jan 2013 has a lot on it (although the paper as a whole was very straightforward)
Original post by Ayman!
Anyone tried the January 2016 IAL paper? It's super nice, haha.


Just did it today, it was my highest raw mark on a paper
Original post by samb1234
Oh btw you may have done it already but if you still want spectroscopy practice the last question of jan 2013 has a lot on it (although the paper as a whole was very straightforward)


Thanks man, will have a look sometime tomorrow. I have one past paper left - IAL June 2015. Apparently the UK variant was exactly the same?

Original post by Whizbox
Just did it today, it was my highest raw mark on a paper


Same! I was surprised that I barely dropped any marks. Usually doesn't happen. :lol:
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samb1234
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Original post by Ayman!
Thanks man, will have a look sometime tomorrow. I have one past paper left - IAL June 2015. Apparently the UK variant was exactly the same?



Same! I was surprised that I barely dropped any marks. Usually doesn't happen. :lol:


The theme is the same but there are slight differences e.g. the buffer is an alkali one instead, slightly different scenario for the oil one so its worth having a look at at the very least. 2013 jan is definitely the nicest paper ive done so far haha
Hey guys,
Just wanted to ask how the A* works, Is it an average of the two papers equally 90% or both papers have to have a minimum of 90%?
Hope you all are ready for the exams and I wish you all the best!
Original post by MacroniCheese
Hey guys,
Just wanted to ask how the A* works, Is it an average of the two papers equally 90% or both papers have to have a minimum of 90%?
Hope you all are ready for the exams and I wish you all the best!


You have to get 270/300 UMS this year (and 480/600 overall I believe) :smile:
Guys does anyone have a good resource for Kc questions? I keep messing up on them for some reason... XD
Original post by Don Pedro K.
Guys does anyone have a good resource for Kc questions? I keep messing up on them for some reason... XD


What do you get wrong?
Original post by Whizbox
What do you get wrong?


Well in the Jan 15 (IAL) paper for example I failed to realise that the NaOH used for titration reacted with the equilibrium mixture of ethanoic acid + HCl acid rather than the initial mixture.

I also got this one completely wrong (section C):

https://c838cff4741acb48ae1ed62e59927ff4c2073557.googledrive.com/host/0B1ZiqBksUHNYbVpyRTRJN1lFS00/June%202014%20QP%20-%20Unit%204%20Edexcel%20Chemistry.pdf

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