The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

OCR B F335 - Chemistry by Design - 13th June 2012

Scroll to see replies

Original post by Ilyas
what's the boundary for an A?


85/120
Reply 201
Avatar for Iepnauy
Iepnauy
9
This exam is brutal =(.

Wish I started revising for it earlier. Did horrifically on the past paper I just did =/
Original post by Iepnauy
This exam is brutal =(.

Wish I started revising for it earlier. Did horrifically on the past paper I just did =/


the boundaries are quiet low usually, so dont worry youll be okay :smile:
Reply 203
Avatar for navarre
navarre
20
Original post by master_blaster66
the boundaries are quiet low usually, so dont worry youll be okay :smile:


You generally need over 85 for an A, which is pretty hard. This exam is absolutely horrific.
Original post by navarre
You generally need over 85 for an A, which is pretty hard. This exam is absolutely horrific.

in f335 the highest ive seen is 84 or 85 but it can also go down to 80...and yes i agree, its the hardest exam by miles, but just hope we get a nice exam :smile:
Reply 205
Avatar for 301lw
301lw
Original post by Ilyas
Kc=[CO]2[O2][CO2]2K_c = \frac{[CO]^2[O_2]}{[CO_2]^2}

can you see why now?

EDIT: You are actually correct, 4x10^-20 is correct. Look at the ms.




no. Raise it to the power of the mole, don't multiply.


of course! ah that's so silly of me, thanks for correcting me :smile:
Reply 206
Avatar for Iepnauy
Iepnauy
9
Original post by master_blaster66
the boundaries are quiet low usually, so dont worry youll be okay :smile:


I'm struggling to hit that A boundary :redface:

I dislike how pretty much every mark is extremely specific, it's not like biology where a 6 marker question can have 9 possible answers, in chemistry they want those exact 4 points (alternative wording). Oh well, more cramming to do tonight.
Reply 207
Avatar for navarre
navarre
20
Original post by master_blaster66
in f335 the highest ive seen is 84 or 85 but it can also go down to 80...and yes i agree, its the hardest exam by miles, but just hope we get a nice exam :smile:


Same here mate. What we need are 5/6 markers on benzene AND colour, and a nice big question on buffers. If we get all three, I'm laughing.

BTW, for the electrophilic substitution of benzene with sulfur trioxide, what is everyone else putting? I know CGP revision guide says fuming sulfuric acid at 40oC, but that isn't in Chemical Ideas.

I'm just gonna stick with conc. sulfuric acid and heat under reflux methinks.
Original post by navarre
Same here mate. What we need are 5/6 markers on benzene AND colour, and a nice big question on buffers. If we get all three, I'm laughing.

BTW, for the electrophilic substitution of benzene with sulfur trioxide, what is everyone else putting? I know CGP revision guide says fuming sulfuric acid at 40oC, but that isn't in Chemical Ideas.

I'm just gonna stick with conc. sulfuric acid and heat under reflux methinks.


im defo putting conc. sulfuric acid , heat under reflux for several hours
Original post by master_blaster66
in f335 the highest ive seen is 84 or 85 but it can also go down to 80...and yes i agree, its the hardest exam by miles, but just hope we get a nice exam :smile:


I've seen 90/120 for an A... luckily I got 94. And tbh it was actually a fairly standard paper!
Original post by Ilyas
I've seen 90/120 for an A... luckily I got 94. And tbh it was actually a fairly standard paper!


hmm do you think :/...90/120? what paper was that
I have a question about entropy.

If we're talking about dissolving and crystallisation of salts, if we add more salt then this causes the entropy of the solution to increase because we're increasing the number of ions (and therefore the possible arrangement in space). But at the same time, the space in which the ions can be distributed decreases so the entropy decreases. So overall, what happens to the entropy?

If we just heat the solution so that the concentration rises but the number of ions stays the same then entropy decreases. What would have happen in the above scenario? :s-smilie:
Original post by Tamagotchi
I have a question about entropy.

If we're talking about dissolving and crystallisation of salts, if we add more salt then this causes the entropy of the solution to increase because we're increasing the number of ions (and therefore the possible arrangement in space). But at the same time, the space in which the ions can be distributed decreases so the entropy decreases. So overall, what happens to the entropy?

If we just heat the solution so that the concentration rises but the number of ions stays the same then entropy decreases. What would have happen in the above scenario? :s-smilie:


is this from a past paper? I would argue that the entropy increases. This idea of 'space' isn't really relevent, if you added more ions the size of the crystals will just increase proportionally, so technically number of arrangements increases.

Imagine if I added 1000^1000000000000 molecules of salt, they are not all going to fit into the crystal system, they will just expand the crystal system (the whole college would be packed with crystals).

that's just my opinion, I'm 99.99% sure they won't ask something of this nature.
(edited 11 years ago)
Original post by master_blaster66
hmm do you think :/...90/120? what paper was that


june 2008 old spec (chem by design)
Original post by navarre
What we need are 5/6 markers on benzene AND colour, and a nice big question on buffers. If we get all three, I'm laughing.


That would actually be amazing.
But I have a feeling they're going to make it trickier and not just have those questions as 6 markers where everyone will write down everything they've memorised for past papers.
Does anybody want to revise over MSN? :smile:
Original post by Ilyas
is this from a past paper? I would argue that the entropy increases. This idea of 'space' isn't really relevent, if you added more ions the size of the crystals will just increase proportionally, so technically number of arrangements increases.

Imagine if I added 1000^1000000000000 molecules of salt, they are not all going to fit into the crystal system, they will just expand the crystal system (the whole college would be packed with crystals).

that's just my opinion, I'm 99.99% sure they won't ask something of this nature.


What do you mean by the crystal system?
Original post by Ilyas
I've seen 90/120 for an A... luckily I got 94. And tbh it was actually a fairly standard paper!


did you say the june06 paper was standard?
Reply 218
Avatar for navarre
navarre
20
Original post by SimpleGirl
That would actually be amazing.
But I have a feeling they're going to make it trickier and not just have those questions as 6 markers where everyone will write down everything they've memorised for past papers.


Same, although the liklihood is is that they will do at least one out of benzene/colour/buffers. They've gotta give those 6 marks out somehow, and they can't do it asking what the systematic name for HCO3- is. There's only ever going to be a limited number of big mark questions they can ask, although they may change the wording and points in the mark scheme from year to year.

TBH, I'm revising stuff like GLC, dyes and carbon dioxide a great deal- there's a LOT of scope to go into detail on those topics, in a way I haven't seen in past papers.
(edited 11 years ago)
Original post by navarre
Same, although the liklihood is is that they will do at least one out of benzene/colour/buffers. They've gotta give those 6 marks out somehow, and they can't do it asking what the systematic name for HCO3- is. There's only ever going to be a limited number of big mark questions they can ask, although they may change the wording and points in the mark scheme from year to year.

TBH, I'm revising stuff like GLC, dyes and carbon dioxide a great deal- there's a LOT of scope to go into detail on those topics, in a way I haven't seen in past papers.


can you explain what youve learnt about glc?..that would be good

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you